Modeling the potential effects of climate change on high elevation vegetation in the Olympic Mountains

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zolbrod, A.N.; Peterson, D.L.

1995-06-01

Subalpine and alpine vegetation may be particularly sensitive to climatic change, such as expected temperature increases and altered precipitation patterns with global warming. The gap replacement model ZELIG was modified and used to examine transient and steady-state changes in altitudinal treeline, tree species distribution, and forest structure and composition along elevation gradients in the Olympic Mountains, Washington, under a range of temperature and precipitation changes. Changes in vegetation pattern were examined for north vs. south aspects, and wet (southwest) vs. dry (northeast) regions of the mountains. The seedling establishment subroutine in ZELIG was improved to specifically model the complexities ofmore » tree invasion in subalpine meadows and include empirical data. A function allowing for stand replacement fire was also added in order to examine the role of altered disturbance regimes on vegetation change. Results indicate that distribution of tree species will change under various climate change scenarios, but future elevation of treeline depends greatly on precipitation levels, disturbance frequency, and aspect.« less

Patterns of foraging and distribution of bluegill sunfish in a Mississippi River backwater: Influence of macrophytes and predation

USGS Publications Warehouse

Dewey, M.R.; Richardson, W.B.; Zigler, S.J.

1997-01-01

We studied the trophic interactions and spatial distributions of bluegills Lepomis macrochirus and largemouth bass Micropterus salmoides in a macrophyte bed in Lake Onalaska, a backwater lake in the upper Mississippi River. The diets of adult and age-0 bluegills were similar and changed seasonally probably in response to changes in life stages of macroinvertebrates (i.e. emergence of winged adults). Diets and diel patterns of abundance of bluegill suggest that age-0 and adults were feeding in the vegetated, littoral zone. Predation by age-0 largemouth bass appears to influence use of vegetated habitat by age-0 bluegills. In summer, when most age-0 bluegills were vulnerable to predation by age-0 largemouth bass, bluegill abundance was strongly correlated with vegetation biomass. In October and November, piscivory by age-0 largemouth bass was limited by gape. Consequently, the relationship between the abundance of age-0 bluegills and vegetation biomass was weakened because predation risk by age-0 largemouth bass was reduced.

Contrasting distribution patterns of invasive and naturalized non-native species along environmental gradients in a semi-arid montane ecosystem

Treesearch

Kelly M. Andersen; Bridgett J. Naylor; Bryan A. Endress; Catherine G. Parks

2015-01-01

Questions: Mountain systems have high abiotic heterogeneity over local spatial scales, offering natural experiments for examining plant species invasions. We ask whether functional groupings explain non-native species spread into native vegetation and up elevation gradients.We examine whether non-native species distribution patterns are related to environmental...

Riparian vegetation patterns in relation to fluvial landforms and channel evolution along selected rivers of Tuscany (Central Italy)

USGS Publications Warehouse

Hupp, C.R.; Rinaldi, M.

2007-01-01

Riparian vegetation distribution patterns and diversity relative to various fluvial geomorphic channel patterns, landforms, and processes are described and interpreted for selected rivers of Tuscany, Central Italy; with emphasis on channel evolution following human impacts. Field surveys were conducted along thirteen gauged reaches for species presence, fluvial landforms, and the type and amount of channel/riparian zone change. Inundation frequency of different geomorphic surfaces was determined, and vegetation data were analyzed using BDA (binary discriminate analysis) and DCA (detrended correspondence analysis) and related to hydrogeomorphology. Multivariate analyses revealed distinct quantitative vegetation patterns relative to six major fluvial geomorphic surfaces. DCA of the vegetation data also showed distinct associations of plants to processes of adjustment that are related to stage of channel evolution, and clearly separated plants along disturbance/landform/soil moisture gradients. Species richness increases from the channel bed to the terrace and on heterogeneous riparian areas, whereas species richness decreases from moderate to intense incision and from low to intense narrowing. ?? 2007 by Association of American Geographers.

Environmental variation, vegetation distribution, carbon dynamics and water/energy exchange at high latitudes

USGS Publications Warehouse

McGuire, A.D.; Wirth, C.; Apps, M.; Beringer, J.; Clein, J.; Epstein, H.; Kicklighter, D.W.; Bhatti, J.; Chapin, F. S.; De Groot, B.; Efremov, D.; Eugster, W.; Fukuda, M.; Gower, T.; Hinzman, L.; Huntley, B.; Jia, G.J.; Kasischke, E.; Melillo, J.; Romanovsky, V.; Shvidenko, A.; Vaganov, E.; Walker, D.

2002-01-01

The responses of high latitude ecosystems to global change involve complex interactions among environmental variables, vegetation distribution, carbon dynamics, and water and energy exchange. These responses may have important consequences for the earth system. In this study, we evaluated how vegetation distribution, carbon stocks and turnover, and water and energy exchange are related to environmental variation spanned by the network of the IGBP high latitude transects. While the most notable feature of the high latitude transects is that they generally span temperature gradients from southern to northern latitudes, there are substantial differences in temperature among the transects. Also, along each transect temperature co-varies with precipitation and photosynthetically active radiation, which are also variable among the transects. Both climate and disturbance interact to influence latitudinal patterns of vegetation and soil carbon storage among the transects, and vegetation distribution appears to interact with climate to determine exchanges of heat and moisture in high latitudes. Despite limitations imposed by the data we assembled, the analyses in this study have taken an important step toward clarifying the complexity of interactions among environmental variables, vegetation distribution, carbon stocks and turnover, and water and energy exchange in high latitude regions. This study reveals the need to conduct coordinated global change studies in high latitudes to further elucidate how interactions among climate, disturbance, and vegetation distribution influence carbon dynamics and water and energy exchange in high latitudes.

Signal and noise in vegetation patterns in drylands: distinguishing the baby from the bath water

NASA Astrophysics Data System (ADS)

Parsons, Anthony; Wainwright, John; Stewart, Jill; Okin, Gregory

2014-05-01

Patterns, and particularly banded patterns, are widely reported in dryland vegetation, and have been the subject of considerable modelling effort. However, much of this modelling effort is predicated on a mathematical approach that is designed to produce patterns and relies on physical processes that are unreasonable. In consequence, whereas in nature dryland vegetation patterns are irregular, disjointed and discontinuous, those produced by such models tend to be regular, continuous and even. The question, therefore, arises "Is it the irregularity, disjointed and discontinuous character of these patterns that holds the key to their formation rather than any apparent, human-imposed semblance of regularity and continuity?" By focusing on this apparent patterning have such models rejected as noise the key to understanding the signal? Models that produce regular vegetation patterns, typically do so by imposing global rules (largely for the distribution of water). Is it not more likely that vegetation responds to the local supply of water, nutrients and propagules? Here, we present a model for the growth of vegetation in deserts that is predicated on the local conditions of input of water, nutrients and propagules and output, such as loss of biomass by herbivory. The approach represents our best quantitative understanding of how desert ecosystems work. Patterns emerge that show the irregularity and discontinuity seen in nature. By focusing on the process rather than the patterns per se our model has the ability to address specific questions of the role of such patterns in land degradation. Further, it has the potential to provide quantitative estimates of the response of the landscape to specific management strategies, as well as the identification of the key thresholds and tipping points that are so important to the management of drylands. In providing a way to understand and predict the vegetation patterns that may develop during desertification, the approach also represents a crucial potential tool for its management and even reversal.

Climatological determinants of woody cover in Africa.

PubMed

Good, Stephen P; Caylor, Kelly K

2011-03-22

Determining the factors that influence the distribution of woody vegetation cover and resolving the sensitivity of woody vegetation cover to shifts in environmental forcing are critical steps necessary to predict continental-scale responses of dryland ecosystems to climate change. We use a 6-year satellite data record of fractional woody vegetation cover and an 11-year daily precipitation record to investigate the climatological controls on woody vegetation cover across the African continent. We find that-as opposed to a relationship with only mean annual rainfall-the upper limit of fractional woody vegetation cover is strongly influenced by both the quantity and intensity of rainfall events. Using a set of statistics derived from the seasonal distribution of rainfall, we show that areas with similar seasonal rainfall totals have higher fractional woody cover if the local rainfall climatology consists of frequent, less intense precipitation events. Based on these observations, we develop a generalized response surface between rainfall climatology and maximum woody vegetation cover across the African continent. The normalized local gradient of this response surface is used as an estimator of ecosystem vegetation sensitivity to climatological variation. A comparison between predicted climate sensitivity patterns and observed shifts in both rainfall and vegetation during 2009 reveals both the importance of rainfall climatology in governing how ecosystems respond to interannual fluctuations in climate and the utility of our framework as a means to forecast continental-scale patterns of vegetation shifts in response to future climate change.

Reconstruction of the vegetation distribution of different topographic units of the Chinese Loess Plateau during the Holocene

NASA Astrophysics Data System (ADS)

Sun, Aizhi; Guo, Zhengtang; Wu, Haibin; Li, Qin; Yu, Yanyan; Luo, Yunli; Jiang, Wenying; Li, Xiaoqiang

2017-10-01

Soil erosion and related ecological restoration present a tremendous challenge to the socioeconomic development of the Chinese Loess Plateau (CLP). Although the Chinese government has addressed the problem of soil erosion via an afforestation programme, there have been several negative outcomes. One of the reasons for this is our incomplete understanding of the past natural vegetation distribution in the various topographic units of the CLP under different climate scenarios. Consequently, we used fossil pollen data from 41 sites from different topographic units, together with the biomization method, to reconstruct the Holocene vegetation distribution of the CLP. The results demonstrate significant differences in vegetation types between different topographic units: forest was distributed in mountainous areas, steppe was dominant in Yuan areas, and desert vegetation was distributed in the transition zone between loess and desert. The vegetation in the gully areas exhibited significant spatial differences during the mid-Holocene. In addition, the vegetation on the various topographic units was well-developed during the interval from 9 to 4 ka B.P., when regional moisture levels reached a maximum. This suggests that the East Asian Summer Monsoon was one of the main factors controlling the evolution of vegetation patterns during the Holocene. In addition, our results confirm that both topography and human activity were fundamental factors determining the vegetation distribution of the region. Against a background of ongoing global warming, we advocate a program of vegetation restoration including planting trees and shrubs in the mountainous areas, and promoting the growth of grasses in the Yuan areas and in the transitional zone between loess and desert. In the gully areas, the planting of trees and shrubs is appropriate for reducing soil erosion caused by human activities.

[Relation between species distribution of plant community and soil factors under grazing in alpine meadow].

PubMed

Niu, Yu Jie; Yang, Si Wei; Wang, Gui Zhen; Liu, Li; Du, Guo Zhen; Hua, Li Min

2017-12-01

The research selected the alpine meadow located in the northeastern margin of the Qinghai-Tibet Plateau to study the changes of vegetation community and soil properties under different grazing intensities, as well as the quantitative relation between the distribution patterns of plant species and the physical and chemical properties of soil. The results showed that the grazing caused the differentiation of the initial vegetation community with the dominant plants, Elymus nutans and Stipa grandis. In the plots with high and low grazing intensities, the dominant plants had changed to Kobresia humilis and Melissitus ruthenica, and E. nutans and Poa crymophila, respectively. With the increase of grazing intensity, the plant richness, importance value and biomass were significantly decreased. The sequence of plant species importance value in each plot against grazing intensity could be fitted by a logarithmic model. The number of required plant species was reduced while the importance value of the remaining plant species accounted for 50% of the importance value in the whole vegetation community. The available P, available K, soil compaction, soil water content, stable infiltration rate and large aggregate index were significantly changed with grazing intensity, however, the changes were different. The CCA ordination showed that the soil compaction was the key factor affecting the distribution pattern of the plant species under grazing. The variance decomposition indicated that the soil factors together explained 30.5% of the distribution of the plant species, in particular the soil physical properties alone explained 22.8% of the distribution of the plant species, which had the highest rate of contribution to the plant species distribution. The soil physical properties affected the distribution pattern of plant species on grazed alpine meadow.

Monitoring Agricultural Cropping Patterns in the Great Lakes Basin Using MODIS-NDVI Time Series Data

EPA Science Inventory

This research examined changes in agricultural cropping patterns across the Great Lakes Basin (GLB) using the Moderate Resolution Imaging Spectroradiometer (MODIS) Normalized Difference Vegetation Index (NDVI) data. Specific research objectives were to characterize the distribut...

Effects of Heterogeniety on Spatial Pattern Analysis of Wild Pistachio Trees in Zagros Woodlands, Iran

NASA Astrophysics Data System (ADS)

Erfanifard, Y.; Rezayan, F.

2014-10-01

Vegetation heterogeneity biases second-order summary statistics, e.g., Ripley's K-function, applied for spatial pattern analysis in ecology. Second-order investigation based on Ripley's K-function and related statistics (i.e., L- and pair correlation function g) is widely used in ecology to develop hypothesis on underlying processes by characterizing spatial patterns of vegetation. The aim of this study was to demonstrate effects of underlying heterogeneity of wild pistachio (Pistacia atlantica Desf.) trees on the second-order summary statistics of point pattern analysis in a part of Zagros woodlands, Iran. The spatial distribution of 431 wild pistachio trees was accurately mapped in a 40 ha stand in the Wild Pistachio & Almond Research Site, Fars province, Iran. Three commonly used second-order summary statistics (i.e., K-, L-, and g-functions) were applied to analyse their spatial pattern. The two-sample Kolmogorov-Smirnov goodness-of-fit test showed that the observed pattern significantly followed an inhomogeneous Poisson process null model in the study region. The results also showed that heterogeneous pattern of wild pistachio trees biased the homogeneous form of K-, L-, and g-functions, demonstrating a stronger aggregation of the trees at the scales of 0-50 m than actually existed and an aggregation at scales of 150-200 m, while regularly distributed. Consequently, we showed that heterogeneity of point patterns may bias the results of homogeneous second-order summary statistics and we also suggested applying inhomogeneous summary statistics with related null models for spatial pattern analysis of heterogeneous vegetations.

Quantitative characterization of the regressive ecological succession by fractal analysis of plant spatial patterns

USGS Publications Warehouse

Alados, C.L.; Pueyo, Y.; Giner, M.L.; Navarro, T.; Escos, J.; Barroso, F.; Cabezudo, B.; Emlen, J.M.

2003-01-01

We studied the effect of grazing on the degree of regression of successional vegetation dynamic in a semi-arid Mediterranean matorral. We quantified the spatial distribution patterns of the vegetation by fractal analyses, using the fractal information dimension and spatial autocorrelation measured by detrended fluctuation analyses (DFA). It is the first time that fractal analysis of plant spatial patterns has been used to characterize the regressive ecological succession. Plant spatial patterns were compared over a long-term grazing gradient (low, medium and heavy grazing pressure) and on ungrazed sites for two different plant communities: A middle dense matorral of Chamaerops and Periploca at Sabinar-Romeral and a middle dense matorral of Chamaerops, Rhamnus and Ulex at Requena-Montano. The two communities differed also in the microclimatic characteristics (sea oriented at the Sabinar-Romeral site and inland oriented at the Requena-Montano site). The information fractal dimension increased as we moved from a middle dense matorral to discontinuous and scattered matorral and, finally to the late regressive succession, at Stipa steppe stage. At this stage a drastic change in the fractal dimension revealed a change in the vegetation structure, accurately indicating end successional vegetation stages. Long-term correlation analysis (DFA) revealed that an increase in grazing pressure leads to unpredictability (randomness) in species distributions, a reduction in diversity, and an increase in cover of the regressive successional species, e.g. Stipa tenacissima L. These comparisons provide a quantitative characterization of the successional dynamic of plant spatial patterns in response to grazing perturbation gradient. ?? 2002 Elsevier Science B.V. All rights reserved.

Vegetation ecogeomorphology, dynamic equilibrium, and disturbance: chapter 7

USGS Publications Warehouse

Hupp, Cliff R.

2013-01-01

Early ecologists understood the need to document geomorphic form and process to explain plant species distributions. Although this relationship has been acknowledged for over a century, with the exception of a few landmark papers, only the past few decades have experienced intensive research on this interdisciplinary topic. Here the authors provide a summary of the intimate relations between vegetation and geomorphic/process on hillslopes and fluvial systems. These relations are separated into systems (primarily fluvial) in dynamic equilibrium and those that are in nonequilibrium conditions including the impacts of various human disturbances affecting landforms, geomorphic processes, and interrelated, attendant vegetation patterns and processes. The authors conclude with a conceptual model of stream regime focusing on sediment deposition, erosion, and equilibrium that can be expanded to organize and predict vegetation patterns and life history strategies.

Vegetation recovery patterns assessment at landslides caused by catastrophic earthquake: a case study in central Taiwan.

PubMed

Chou, Wen-Chieh; Lin, Wen-Tzu; Lin, Chao-Yuan

2009-05-01

The catastrophic earthquake, 7.3 on the Richter scale, occurred on September 21, 1999 in Central Taiwan. Much of standing vegetation on slopes was eliminated and massive, scattered landslides were induced at the Jou-Jou Mountain area of the Wu-Chi basin in Nantou County. We evaluated three methods for assessing landslide hazard and vegetation recovery conditions. (1) Self-organizing map (SOM) neural network coupled with fuzzy technique was used to quickly extract the landslide. (2) The NDVI-based vegetation recovery index derived from multi-temporal SPOT satellite images was used to evaluate vegetation recovery rate in the denudation sites. (3) The spatial distribution index (SDI) based on land-cover topographic location was employed to analyze vegetation recovery patterns, including the invading, surviving and mixed patterns at the Jou-Jou Mountain area. On September 27, 1999, there were 849.20 ha of landslide area extracted using the self-organizing map and fuzzy technique combined model. After six years of natural vegetation succession, the landslide has gradually restored, and vegetation recovery rate reached up to 86%. On-site observation shows that many native pioneer plants have invaded onto the denudation sites even if disturbed by several typhoons. Two native surviving plants, Arundo formosana Hack and Pinus taiwanensis Hayata, play a vital role in natural vegetation succession in this area, especially for the sites on ridgeline and steep slopes.

Analysis of Biophysical Mechanisms of Gilgai Microrelief Formation in Dryland Swelling Soils Using Ultra-High Resolution Aerial Imagery

NASA Astrophysics Data System (ADS)

Krell, N.; DeCarlo, K. F.; Caylor, K. K.

2015-12-01

Microrelief formations ("gilgai"), which form due to successive wetting-drying cycles typical of swelling soils, provide ecological hotspots for local fauna and flora, including higher and more robust vegetative growth. The distribution of these gilgai suggests a remarkable degree of regularity. However, it is unclear to what extent the mechanisms that drive gilgai formation are physical, such as desiccation-induced fracturing, or biological in nature, namely antecedent vegetative clustering. We investigated gilgai genesis and pattern formation in a 100 x 100 meter study area with swelling soils in a semiarid grassland at the Mpala Research Center in central Kenya. Our ongoing experiment is composed of three 9m2 treatments: we removed gilgai and limited vegetative growth by herbicide application in one plot, allowed for unrestricted seed dispersal in another, and left gilgai unobstructed in a control plot. To estimate the spatial frequencies of the repeating patterns of gilgai, we obtained ultra-high resolution (0.01-0.03m/pixel) images with an unmanned aerial vehicle (UAV) from which digital elevation models were also generated. Geostatistical analyses using wavelet and fourier methods in 1- and 2-dimensions were employed to characterize gilgai size and distribution. Preliminary results support regular spatial patterning across the gilgaied landscape and heterogeneities may be related to local soil properties and biophysical influences. Local data on gilgai and fracture characteristics suggest that gilgai form at characteristic heights and spacing based on fracture morphology: deep, wide cracks result in large, highly vegetated mounds whereas shallow cracks, induced by animal trails, are less correlated with gilgai size and shape. Our experiments will help elucidate the links between shrink-swell processes and gilgai-vegetation patterning in high activity clay soils and advance our understanding of the mechanisms of gilgai formation in drylands.

Using repeat electrical resistivity surveys to assess heterogeneity in soil moisture dynamics under contrasting vegetation types

NASA Astrophysics Data System (ADS)

Dick, Jonathan; Tetzlaff, Doerthe; Bradford, John; Soulsby, Chris

2018-04-01

As the relationship between vegetation and soil moisture is complex and reciprocal, there is a need to understand how spatial patterns in soil moisture influence the distribution of vegetation, and how the structure of vegetation canopies and root networks regulates the partitioning of precipitation. Spatial patterns of soil moisture are often difficult to visualise as usually, soil moisture is measured at point scales, and often difficult to extrapolate. Here, we address the difficulties in collecting large amounts of spatial soil moisture data through a study combining plot- and transect-scale electrical resistivity tomography (ERT) surveys to estimate soil moisture in a 3.2 km2 upland catchment in the Scottish Highlands. The aim was to assess the spatio-temporal variability in soil moisture under Scots pine forest (Pinus sylvestris) and heather moorland shrubs (Calluna vulgaris); the two dominant vegetation types in the Scottish Highlands. The study focussed on one year of fortnightly ERT surveys. The surveyed resistivity data was inverted and Archie's law was used to calculate volumetric soil moisture by estimating parameters and comparing against field measured data. Results showed that spatial soil moisture patterns were more heterogeneous in the forest site, as were patterns of wetting and drying, which can be linked to vegetation distribution and canopy structure. The heather site showed a less heterogeneous response to wetting and drying, reflecting the more uniform vegetation cover of the shrubs. Comparing soil moisture temporal variability during growing and non-growing seasons revealed further contrasts: under the heather there was little change in soil moisture during the growing season. Greatest changes in the forest were in areas where the trees were concentrated reflecting water uptake and canopy partitioning. Such differences have implications for climate and land use changes; increased forest cover can lead to greater spatial variability, greater growing season temporal variability, and reduced levels of soil moisture, whilst projected decreasing summer precipitation may alter the feedbacks between soil moisture and vegetation water use and increase growing season soil moisture deficits.

Techniques for spatio-temporal analysis of vegetation fires in the topical belt of Africa

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brivio, P.A.; Ober, G.; Koffi, B.

1995-12-31

Biomass burning of forests and savannas is a phenomenon of continental or even global proportions, capable of causing large scale environmental changes. Satellite space observations, in particular from NOAA-AVHRR GAC data, are the only source of information allowing one to document burning patterns at regional and continental scale and over long periods of time. This paper presents some techniques, such as clustering and rose-diagram, useful in the spatial-temporal analysis of satellite derived fires maps to characterize the evolution of spatial patterns of vegetation fires at regional scale. An automatic clustering approach is presented which enables one to describe and parameterizemore » spatial distribution of fire patterns at different scales. The problem of geographical distribution of vegetation fires with respect to some location of interest, point or line, is also considered and presented. In particular rose-diagrams are used to relate fires patterns to some reference point, as experimental sites of tropospheric chemistry measurements. Different temporal data-sets in the tropical belt of Africa, covering both Northern and Southern Hemisphere dry seasons, using these techniques were analyzed and showed very promising results when compared with data from rain chemistry studies at different sampling sites in the equatorial forest.« less

Solar radiation as a global driver of hillslope asymmetry: Insights from an ecogeomorphic landscape evolution model

NASA Astrophysics Data System (ADS)

Yetemen, Omer; Istanbulluoglu, Erkan; Duvall, Alison R.

2015-12-01

Observations at the field, catchment, and continental scales across a range of arid and semiarid climates and latitudes reveal aspect-controlled patterns in soil properties, vegetation types, ecohydrologic fluxes, and hillslope morphology. Although the global distribution of solar radiation on earth's surface and its implications on vegetation dynamics are well documented, we know little about how variation of solar radiation across latitudes influence landscape evolution and resulting geomorphic difference. Here, we used a landscape evolution model that couples the continuity equations for water, sediment, and aboveground vegetation biomass at each model element in order to explore the controls of latitude and mean annual precipitation (MAP) on the development of hillslope asymmetry (HA). In our model, asymmetric hillslopes emerged from the competition between soil creep and vegetation-modulated fluvial transport, driven by spatial distribution of solar radiation. Latitude was a primary driver of HA because of its effects on the global distribution of solar radiation. In the Northern Hemisphere, north-facing slopes (NFS), which support more vegetation cover and have lower transport efficiency, get steeper toward the North Pole while south-facing slopes (SFS) get gentler. In the Southern Hemisphere, the patterns are reversed and SFS get steeper toward the South Pole. For any given latitude, MAP is found to have minor control on HA. Our results underscore the potential influence of solar radiation as a global control on the development of asymmetric hillslopes in fluvial landscapes.

Understanding patterns of vegetation structure and distribution across Great Smoky Mountains National Park using LiDAR and meteorology data

NASA Astrophysics Data System (ADS)

Kumar, J.; Hargrove, W. W.; Norman, S. P.; Hoffman, F. M.

2017-12-01

Great Smoky Mountains National Park (GSMNP) in Tennessee is a biodiversity hotspot and home to a large number of plant, animal and bird species. Driven by gradients of climate (ex. temperature, precipitation regimes), topography (ex. elevation, slope, aspect), geology (ex. soil types, textures, depth), hydrology (ex. drainage, moisture availability) etc. GSMNP offers a diverse composition and distribution of vegetation which in turn supports an array of wildlife. Understanding the vegetation canopy structure is critical to understand, monitor and manage the complex forest ecosystems like the Great Smoky Mountain National Park (GSMNP). Vegetation canopies not only help understand the vegetation, but are also a critically important habitat characteristics of many threatened and endangered animal and bird species that GSMNP is home to. Using airborne Light Detection and Ranging (LiDAR) we characterize the three-dimensional structure of the vegetation. LiDAR based analysis gives detailed insight in the canopy structure (overstory and understory) and its spatial variability within and across forest types. Vegetation structure and spatial distribution show strong correlation with climate, topographic, and edaphic variables and our multivariate analysis not just mines rich and large LiDAR data but presents ecological insights and data for vegetation within the park that can be useful to forest managers in their management and conservation efforts.

Ground-flora communities of headwater riparian areas in an old-growth central hardwood forest

Treesearch

P. Charles Goebel; David M. Hix; Clayton E. Dygert; Kathryn L. Holmes

2003-01-01

The composition and structure of ground-flora vegetation was examined across headwater riparian areas of Johnson Woods, an old-growth forest located in northcentral Ohio. While the distribution patterns of these species groups is variable, classification and gradient analyses indicate that ground-flora vegetation is related strongly to landform and distance from the...

Changes of Vegetation Distribution in the East Dongting Lake After the Operation of the Three Gorges Dam, China.

PubMed

Hu, Jia-Yu; Xie, Yong-Hong; Tang, Yue; Li, Feng; Zou, Ye-Ai

2018-01-01

Water regime is regarded as the primary factor influencing the vegetation distribution in natural wetland ecosystems. However, the effect of water regime change induced by large-scale hydraulic engineering on vegetation distribution is still unclear. In this study, multi-temporal TM/ETM+/OLI images and hydrological data from 1995 to 2015 were used to elucidate how the change in water regime influenced the vegetation distribution in the East Dongting Lake (EDTL), especially after the operation of the Three Gorges Dam (TGD) in 2003. Using unsupervised and supervised classification methods, three types of land cover were identified in the study area: Water and Mudflat, Grass, and Reed and Forest. Results showed that the total vegetation area in EDTL increased by approximately 78 km 2 during 1995-2015. The areas of Reed and Forest and Grass exhibited a contrasting trend, dramatic increase in Reed and Forest but sharp decrease in Grass, particularly after the operation of TGD. The lowest distribution elevations of Grass and Reed and Forest decreased by 0.61 and 0.52 m, respectively. As a result of water level variation, submergence duration increased at 20-21 m and 28 m elevations (1-13 days), but significantly decreased at 22-27 m and 29-30 m elevations (-3 to -31 days). The submergence duration of Grass and Reed and Forest was 246 and 177 days, respectively. This study indicated that wetland vegetation pattern significantly changed after the operation of TGD, mainly as a result of changes in submergence condition. Submergence duration might be an effective indicator to predict the shift of vegetation distribution in EDTL, and which could provide scientific guidance for vegetation restoration and wetland management in this lake.

Changes of Vegetation Distribution in the East Dongting Lake After the Operation of the Three Gorges Dam, China

PubMed Central

Hu, Jia-Yu; Xie, Yong-Hong; Tang, Yue; Li, Feng; Zou, Ye-Ai

2018-01-01

Water regime is regarded as the primary factor influencing the vegetation distribution in natural wetland ecosystems. However, the effect of water regime change induced by large-scale hydraulic engineering on vegetation distribution is still unclear. In this study, multi-temporal TM/ETM+/OLI images and hydrological data from 1995 to 2015 were used to elucidate how the change in water regime influenced the vegetation distribution in the East Dongting Lake (EDTL), especially after the operation of the Three Gorges Dam (TGD) in 2003. Using unsupervised and supervised classification methods, three types of land cover were identified in the study area: Water and Mudflat, Grass, and Reed and Forest. Results showed that the total vegetation area in EDTL increased by approximately 78 km2 during 1995–2015. The areas of Reed and Forest and Grass exhibited a contrasting trend, dramatic increase in Reed and Forest but sharp decrease in Grass, particularly after the operation of TGD. The lowest distribution elevations of Grass and Reed and Forest decreased by 0.61 and 0.52 m, respectively. As a result of water level variation, submergence duration increased at 20–21 m and 28 m elevations (1–13 days), but significantly decreased at 22–27 m and 29–30 m elevations (-3 to -31 days). The submergence duration of Grass and Reed and Forest was 246 and 177 days, respectively. This study indicated that wetland vegetation pattern significantly changed after the operation of TGD, mainly as a result of changes in submergence condition. Submergence duration might be an effective indicator to predict the shift of vegetation distribution in EDTL, and which could provide scientific guidance for vegetation restoration and wetland management in this lake. PMID:29765388

Solving Large-scale Spatial Optimization Problems in Water Resources Management through Spatial Evolutionary Algorithms

NASA Astrophysics Data System (ADS)

Wang, J.; Cai, X.

2007-12-01

A water resources system can be defined as a large-scale spatial system, within which distributed ecological system interacts with the stream network and ground water system. Water resources management, the causative factors and hence the solutions to be developed have a significant spatial dimension. This motivates a modeling analysis of water resources management within a spatial analytical framework, where data is usually geo- referenced and in the form of a map. One of the important functions of Geographic information systems (GIS) is to identify spatial patterns of environmental variables. The role of spatial patterns in water resources management has been well established in the literature particularly regarding how to design better spatial patterns for satisfying the designated objectives of water resources management. Evolutionary algorithms (EA) have been demonstrated to be successful in solving complex optimization models for water resources management due to its flexibility to incorporate complex simulation models in the optimal search procedure. The idea of combining GIS and EA motivates the development and application of spatial evolutionary algorithms (SEA). SEA assimilates spatial information into EA, and even changes the representation and operators of EA. In an EA used for water resources management, the mathematical optimization model should be modified to account the spatial patterns; however, spatial patterns are usually implicit, and it is difficult to impose appropriate patterns to spatial data. Also it is difficult to express complex spatial patterns by explicit constraints included in the EA. The GIS can help identify the spatial linkages and correlations based on the spatial knowledge of the problem. These linkages are incorporated in the fitness function for the preference of the compatible vegetation distribution. Unlike a regular GA for spatial models, the SEA employs a special hierarchical hyper-population and spatial genetic operators to represent spatial variables in a more efficient way. The hyper-population consists of a set of populations, which correspond to the spatial distributions of the individual agents (organisms). Furthermore spatial crossover and mutation operators are designed in accordance with the tree representation and then applied to both organisms and populations. This study applies the SEA to a specific problem of water resources management- maximizing the riparian vegetation coverage in accordance with the distributed groundwater system in an arid region. The vegetation coverage is impacted greatly by the nonlinear feedbacks and interactions between vegetation and groundwater and the spatial variability of groundwater. The SEA is applied to search for an optimal vegetation configuration compatible to the groundwater flow. The results from this example demonstrate the effectiveness of the SEA. Extension of the algorithm for other water resources management problems is discussed.

Integrating satellite actual evapotranspiration patterns into distributed model parametrization and evaluation for a mesoscale catchment

NASA Astrophysics Data System (ADS)

Demirel, M. C.; Mai, J.; Stisen, S.; Mendiguren González, G.; Koch, J.; Samaniego, L. E.

2016-12-01

Distributed hydrologic models are traditionally calibrated and evaluated against observations of streamflow. Spatially distributed remote sensing observations offer a great opportunity to enhance spatial model calibration schemes. For that it is important to identify the model parameters that can change spatial patterns before the satellite based hydrologic model calibration. Our study is based on two main pillars: first we use spatial sensitivity analysis to identify the key parameters controlling the spatial distribution of actual evapotranspiration (AET). Second, we investigate the potential benefits of incorporating spatial patterns from MODIS data to calibrate the mesoscale Hydrologic Model (mHM). This distributed model is selected as it allows for a change in the spatial distribution of key soil parameters through the calibration of pedo-transfer function parameters and includes options for using fully distributed daily Leaf Area Index (LAI) directly as input. In addition the simulated AET can be estimated at the spatial resolution suitable for comparison to the spatial patterns observed using MODIS data. We introduce a new dynamic scaling function employing remotely sensed vegetation to downscale coarse reference evapotranspiration. In total, 17 parameters of 47 mHM parameters are identified using both sequential screening and Latin hypercube one-at-a-time sampling methods. The spatial patterns are found to be sensitive to the vegetation parameters whereas streamflow dynamics are sensitive to the PTF parameters. The results of multi-objective model calibration show that calibration of mHM against observed streamflow does not reduce the spatial errors in AET while they improve only the streamflow simulations. We will further examine the results of model calibration using only multi spatial objective functions measuring the association between observed AET and simulated AET maps and another case including spatial and streamflow metrics together.

Inferring local competition intensity from patch size distributions: a test using biological soil crusts

USGS Publications Warehouse

Bowker, Matthew A.; Maestre, Fernando T.

2012-01-01

Dryland vegetation is inherently patchy. This patchiness goes on to impact ecology, hydrology, and biogeochemistry. Recently, researchers have proposed that dryland vegetation patch sizes follow a power law which is due to local plant facilitation. It is unknown what patch size distribution prevails when competition predominates over facilitation, or if such a pattern could be used to detect competition. We investigated this question in an alternative vegetation type, mosses and lichens of biological soil crusts, which exhibit a smaller scale patch-interpatch configuration. This micro-vegetation is characterized by competition for space. We proposed that multiplicative effects of genetics, environment and competition should result in a log-normal patch size distribution. When testing the prevalence of log-normal versus power law patch size distributions, we found that the log-normal was the better distribution in 53% of cases and a reasonable fit in 83%. In contrast, the power law was better in 39% of cases, and in 8% of instances both distributions fit equally well. We further hypothesized that the log-normal distribution parameters would be predictably influenced by competition strength. There was qualitative agreement between one of the distribution's parameters (μ) and a novel intransitive (lacking a 'best' competitor) competition index, suggesting that as intransitivity increases, patch sizes decrease. The correlation of μ with other competition indicators based on spatial segregation of species (the C-score) depended on aridity. In less arid sites, μ was negatively correlated with the C-score (suggesting smaller patches under stronger competition), while positive correlations (suggesting larger patches under stronger competition) were observed at more arid sites. We propose that this is due to an increasing prevalence of competition transitivity as aridity increases. These findings broaden the emerging theory surrounding dryland patch size distributions and, with refinement, may help us infer cryptic ecological processes from easily observed spatial patterns in the field.

Seasonal habitat use and selection by grizzly bears in Northern British Columbia

USGS Publications Warehouse

Milakovic, B.; Parker, K.L.; Gustine, D.D.; Lay, R.J.; Walker, A.B.D.; Gillingham, M.P.

2012-01-01

We defined patterns of habitat use and selection by female grizzly bears (Ursus arctos) in the Besa-Prophet watershed of northern British Columbia. We fitted 13 adult females with Geographic Positioning System (GPS) radio-collars and monitored them between 2001 and 2004. We examined patterns of habitat selection by grizzly bears relative to topographical attributes and 3 potential surrogates of food availability: land-cover class, vegetation biomass or quality (as measured by the Normalized Difference Vegetation Index), and selection value for prey species themselves (moose [Alces alces], elk [Cervus elaphus], woodland caribou [Rangifer tarandus], Stone's sheep [Ovis dalli stonei]). Although vegetation biomass and quality, and selection values for prey were important in seasonal selection by some individual bears, land-cover class, elevation, aspect, and vegetation diversity most influenced patterns of habitat selection across grizzly bears, which rely on availability of plant foods and encounters with ungulate prey. Grizzly bears as a group avoided conifer stands and areas of low vegetation diversity, and selected for burned land-cover classes and high vegetation diversity across seasons. They also selected mid elevations from what was available within seasonal ranges. Quantifying relative use of different attributes helped place selection patterns within the context of the landscape. Grizzly bears used higher elevations (1,595??31 m SE) in spring and lower elevations (1,436??27 m) in fall; the range of average elevations used among individuals was highest (500 m) during the summer. During all seasons, grizzly bears most frequented aspects with high solar gain. Use was distributed across 10 land-cover classes and depended on season. Management and conservation actions must maintain a diverse habitat matrix distributed across a large elevational gradient to ensure persistence of grizzly bears as levels of human access increase in the northern Rocky Mountains. ?? 2011 The Wildlife Society. Copyright ?? The Wildlife Society, 2011.

Space-Use Patterns of the Asiatic Wild Ass (Equus hemionus): Complementary Insights from Displacement, Recursion Movement and Habitat Selection Analyses.

PubMed

Giotto, Nina; Gerard, Jean-François; Ziv, Alon; Bouskila, Amos; Bar-David, Shirli

2015-01-01

The way in which animals move and use the landscape is influenced by the spatial distribution of resources, and is of importance when considering species conservation. We aimed at exploring how landscape-related factors affect a large herbivore's space-use patterns by using a combined approach, integrating movement (displacement and recursions) and habitat selection analyses. We studied the endangered Asiatic wild ass (Equus hemionus) in the Negev Desert, Israel, using GPS monitoring and direct observation. We found that the main landscape-related factors affecting the species' space-use patterns, on a daily and seasonal basis, were vegetation cover, water sources and topography. Two main habitat types were selected: high-elevation sites during the day (specific microclimate: windy on warm summer days) and streambed surroundings during the night (coupled with high vegetation when the animals were active in summer). Distribution of recursion times (duration between visits) revealed a 24-hour periodicity, a pattern that could be widespread among large herbivores. Characterizing frequently revisited sites suggested that recursion movements were mainly driven by a few landscape features (water sources, vegetation patches, high-elevation points), but also by social factors, such as territoriality, which should be further explored. This study provided complementary insights into the space-use patterns of E. hemionus. Understanding of the species' space-use patterns, at both large and fine spatial scale, is required for developing appropriate conservation protocols. Our approach could be further applied for studying the space-use patterns of other species in heterogeneous landscapes.

Space-Use Patterns of the Asiatic Wild Ass (Equus hemionus): Complementary Insights from Displacement, Recursion Movement and Habitat Selection Analyses

PubMed Central

Giotto, Nina; Gerard, Jean-François; Ziv, Alon; Bouskila, Amos; Bar-David, Shirli

2015-01-01

The way in which animals move and use the landscape is influenced by the spatial distribution of resources, and is of importance when considering species conservation. We aimed at exploring how landscape-related factors affect a large herbivore’s space-use patterns by using a combined approach, integrating movement (displacement and recursions) and habitat selection analyses. We studied the endangered Asiatic wild ass (Equus hemionus) in the Negev Desert, Israel, using GPS monitoring and direct observation. We found that the main landscape-related factors affecting the species’ space-use patterns, on a daily and seasonal basis, were vegetation cover, water sources and topography. Two main habitat types were selected: high-elevation sites during the day (specific microclimate: windy on warm summer days) and streambed surroundings during the night (coupled with high vegetation when the animals were active in summer). Distribution of recursion times (duration between visits) revealed a 24-hour periodicity, a pattern that could be widespread among large herbivores. Characterizing frequently revisited sites suggested that recursion movements were mainly driven by a few landscape features (water sources, vegetation patches, high-elevation points), but also by social factors, such as territoriality, which should be further explored. This study provided complementary insights into the space-use patterns of E. hemionus. Understanding of the species’ space-use patterns, at both large and fine spatial scale, is required for developing appropriate conservation protocols. Our approach could be further applied for studying the space-use patterns of other species in heterogeneous landscapes. PMID:26630393

Tree species diversity and distribution patterns in tropical forests of Garo Hills.

Treesearch

A. Kumar; B.G. Marcot; A. Saxena

2006-01-01

We analyzed phytosociological characteristics and diversity patterns of tree species of tropical forests of Garo Hills, western Meghalaya, northeast India. The main vegetation of the region included primary forests, secondary forests, and sal (Shorea robusta) plantations, with 162, 132, and 87 tree species, respectively. The Shannon-Wiener...

Landscape-scale processes influence riparian plant composition along a regulated river

USGS Publications Warehouse

Palmquist, Emily C.; Ralston, Barbara; Merritt, David M.; Shafroth, Patrick B.

2018-01-01

Hierarchical frameworks are useful constructs when exploring landscape- and local-scale factors affecting patterns of vegetation in riparian areas. In drylands, which have steep environmental gradients and high habitat heterogeneity, landscape-scale variables, such as climate, can change rapidly along a river's course, affecting the relative influence of environmental variables at different scales. To assess how landscape-scale factors change the structure of riparian vegetation, we measured riparian vegetation composition along the Colorado River through Grand Canyon, determined which factors best explain observed changes, identified how richness and functional diversity vary, and described the implications of our results for river management. Cluster analysis identified three divergent floristic groups that are distributed longitudinally along the river. These groups were distributed along gradients of elevation, temperature and seasonal precipitation, but were not associated with annual precipitation or local-scale factors. Species richness and functional diversity decreased as a function of distance downstream showing that changing landscape-scale factors result in changes to ecosystem characteristics. Species composition and distribution remain closely linked to seasonal precipitation and temperature. These patterns in floristic composition in a semiarid system inform management and provide insights into potential future changes as a result of shifts in climate and changes in flow management.

Urban vegetation and thermal patterns following city growth in different socio-economic contexts

NASA Astrophysics Data System (ADS)

Dronova, I.; Clinton, N.; Yang, J.; Radke, J.; Marx, S. S.; Gong, P.

2015-12-01

Urban expansion accompanied by losses of vegetated spaces and their ecological services raises significant concerns about the future of humans in metropolitan "habitats". Despite recent growth of urban studies globally, it is still not well understood how environmental effects of urbanization vary with the rate and socioeconomic context of development. Our study hypothesized that with urban development, spatial patterns of surface thermal properties and green plant cover would shift towards higher occurrence of relatively warmer and less vegetated spaces such as built-up areas, followed by losses of greener and cooler areas such as urban forests, and that these shifts would be more pronounced with higher rate of economic and/or population growth. To test these ideas, we compared 1992-2011 changes in remotely sensed patterns of green vegetation and surface temperature in three example cities that experienced peripheral growth under contrasting socio-economic context - Dallas, TX, USA, Beijing, China and Kyiv, Ukraine. To assess their transformation, we proposed a metric of thermal-vegetation angle (TVA) estimated from per-pixel proxies of vegetation greenness and surface temperature from Landsat satellite data and examined changes in TVA distributions within each city's core and two decadal zones of peripheral sprawl delineated from nighttime satellite data. We found that higher economic and population growth were coupled with more pronounced changes in TVA distributions, and more urbanized zones often exhibited higher frequencies of warmer, less green than average TVA values with novel patterns such as "cooler" clusters of building shadows. Although greener and cooler spaces generally diminished with development, they remained relatively prevalent in low-density residential areas of Dallas and peripheral zones of Kyiv with exurban subsistence farming. Overall, results indicate that the effects of modified green space and thermal patterns within growing cities highly vary depending on economy, population trends and historical legacies of planned green spaces. Remote sensing-based metrics such as TVA facilitate their comparisons and offer useful strategies to cost-effectively monitor urban transformation and inform more explicit environmental modeling of cities in the future.

Mapping tropical dry forest habitats integrating landsat NDVI, Ikonos imagery, and topographic information in the Caribbean island of Mona.

PubMed

Martinuzzi, Sebastiáin; Gould, William A; Ramos Gonzalez, Olga M; Martinez Robles, Alma; Calle Maldonado, Paulina; Pérez-Buitrago, Néstor; Fumero Caban, José J

2008-06-01

Assessing the status of tropical dry forest habitats using remote sensing technologies is one of the research priorities for Neotropical forests. We developed a simple method for mapping vegetation and habitats in a tropical dry forest reserve, Mona Island, Puerto Rico, by integrating the Normalized Difference Vegetation Index (NDVI) from Landsat, topographic information, and high-resolution Ikonos imagery. The method was practical for identifying vegetation types in areas with a great variety of plant communities and complex relief, and can be adapted to other dry forest habitats of the Caribbean Islands. NDVI was useful for identifying the distribution of forests, woodlands, and shrubland, providing a natural representation of the vegetation patterns on the island. The use of Ikonos imagery allowed increasing the number of land cover classes. As a result, sixteen land-cover types were mapped over the 5500 ha area, with a kappa coefficient of accuracy equal to 79%. This map is a central piece for modeling vertebrate species distribution and biodiversity patterns by the Puerto Rico Gap Analysis Project, and it is of great value for assisting research and management actions in the island.

Analysis of Alaskan burn severity patterns using remotely sensed data

USGS Publications Warehouse

Duffy, P.A.; Epting, J.; Graham, J.M.; Rupp, T.S.; McGuire, A.D.

2007-01-01

Wildland fire is the dominant large-scale disturbance mechanism in the Alaskan boreal forest, and it strongly influences forest structure and function. In this research, patterns of burn severity in the Alaskan boreal forest are characterised using 24 fires. First, the relationship between burn severity and area burned is quantified using a linear regression. Second, the spatial correlation of burn severity as a function of topography is modelled using a variogram analysis. Finally, the relationship between vegetation type and spatial patterns of burn severity is quantified using linear models where variograms account for spatial correlation. These results show that: 1) average burn severity increases with the natural logarithm of the area of the wildfire, 2) burn severity is more variable in topographically complex landscapes than in flat landscapes, and 3) there is a significant relationship between burn severity and vegetation type in flat landscapes but not in topographically complex landscapes. These results strengthen the argument that differential flammability of vegetation exists in some boreal landscapes of Alaska. Additionally, these results suggest that through feedbacks between vegetation and burn severity, the distribution of forest vegetation through time is likely more stable in flat terrain than it is in areas with more complex topography. ?? IAWF 2007.

Remote sensing captures varying temporal patterns of vegetation between human-altered and natural landscapes.

PubMed

Leong, Misha; Roderick, George K

2015-01-01

Global change has led to shifts in phenology, potentially disrupting species interactions such as plant-pollinator relationships. Advances in remote sensing techniques allow one to detect vegetation phenological diversity between different land use types, but it is not clear how this translates to other communities in the ecosystem. Here, we investigated the phenological diversity of the vegetation across a human-altered landscape including urban, agricultural, and natural land use types. We found that the patterns of change in the vegetation indices (EVI and NDVI) of human-altered landscapes are out of synchronization with the phenology in neighboring natural California grassland habitat. Comparing these findings to a spatio-temporal pollinator distribution dataset, EVI and NDVI were significant predictors of total bee abundance, a relationship that improved with time lags. This evidence supports the importance of differences in temporal dynamics between land use types. These findings also highlight the potential to utilize remote sensing data to make predictions for components of biodiversity that have tight vegetation associations, such as pollinators.

[Responses of normalized difference vegetation index (NDVI) to precipitation changes on the grassland of Tibetan Plateau from 2000 to 2015.

PubMed

Wang, Zhi Peng; Zhang, Xian Zhou; He, Yong Tao; Li, Meng; Shi, Pei Li; Zu, Jia Xing; Niu, Ben

2018-01-01

Precipitation change is an important factor in the inter-annual variation of grassland growth on the Tibetan Plateau. The total amount, distribution pattern and concentration time are three basic characteristics of precipitation change. The temporal and spatial characteristics of precipitation change were analyzed based on climate data of 145 meteorological stations on the Tibetan Plateau and nearby areas from 2000 to 2015. The total precipitation amount was characterized by annual precipitation, distribution pattern of precipitation during the year was characterized by improved precipitation concentration index (PCI), and precipitation centroid (PC) was defined to indicate the change in precipitation concentrated time. To better illustrate the response of grassland to precipitation change, vegetation growth status was characterized by the maximum value of normalized difference vegetation index (NDVI max ). Results indicated that the annual precipitation and PCI had an apparent gradient across the whole plateau and the latest PC occurred in the southern plateau. NDVI max of alpine shrub grassland was significantly correlated with the change of PCI,increased with even distribution of precipitation during growth period, and limited by the total annual precipitation. Alpine meadow did not show significantly correlations with these three indices. The inter-annual variability of NDVI max of steppe was controlled by both PCI and PC. NDVI max of alpine desert grassland was mainly controlled by annual precipitation. In addition to annual total amount of precipitation, the distribution characteristics of precipitation should be further considered when the influence of precipitation change on different types of vegetation on the Qinghai Tibet Plateau was studied.

Geographic approaches to biodiversity conservation: implications of scale and error to landscape planning

Treesearch

Curtis H. Flather; Kenneth R. Wilson; Susan A. Shriner

2009-01-01

Conservation science is concerned with understanding why distribution and abundance patterns of species vary in time and space. Although these patterns have strong signatures tied to the availability of energy and nutrients, variation in climate, physiographic heterogeneity, and differences in the structural complexity of natural vegetation, it is becoming more...

Patterns in species composition and diversity along intermittent creeks in the Missouri Ozarks

Treesearch

Cindy E. Becker; Stephen G. Pallardy

2003-01-01

The southeast Missouri Ozarks is a rugged, deeply dissected landscape. Intermittent creeks are commonly found throughout the region, yet our understanding of this ecosystem component is poor. Landform features, flooding frequency, and flooding duration are variables known to affect vegetation distribution patterns along perennial systems. We investigated if these...

Palaeodistribution modelling of European vegetation types at the Last Glacial Maximum using modern analogues from Siberia: Prospects and limitations

NASA Astrophysics Data System (ADS)

Janská, Veronika; Jiménez-Alfaro, Borja; Chytrý, Milan; Divíšek, Jan; Anenkhonov, Oleg; Korolyuk, Andrey; Lashchinskyi, Nikolai; Culek, Martin

2017-03-01

We modelled the European distribution of vegetation types at the Last Glacial Maximum (LGM) using present-day data from Siberia, a region hypothesized to be a modern analogue of European glacial climate. Distribution models were calibrated with current climate using 6274 vegetation-plot records surveyed in Siberia. Out of 22 initially used vegetation types, good or moderately good models in terms of statistical validation and expert-based evaluation were computed for 18 types, which were then projected to European climate at the LGM. The resulting distributions were generally consistent with reconstructions based on pollen records and dynamic vegetation models. Spatial predictions were most reliable for steppe, forest-steppe, taiga, tundra, fens and bogs in eastern and central Europe, which had LGM climate more similar to present-day Siberia. The models for western and southern Europe, regions with a lower degree of climatic analogy, were only reliable for mires and steppe vegetation, respectively. Modelling LGM vegetation types for the wetter and warmer regions of Europe would therefore require gathering calibration data from outside Siberia. Our approach adds value to the reconstruction of vegetation at the LGM, which is limited by scarcity of pollen and macrofossil data, suggesting where specific habitats could have occurred. Despite the uncertainties of climatic extrapolations and the difficulty of validating the projections for vegetation types, the integration of palaeodistribution modelling with other approaches has a great potential for improving our understanding of biodiversity patterns during the LGM.

Historical and contemporary geographic data reveal complex spatial and temporal responses of vegetation to climate and land stewardship

USGS Publications Warehouse

Villarreal, Miguel L.; Norman, Laura M.; Webb, Robert H.; Turner, Raymond M.

2013-01-01

Vegetation and land-cover changes are not always directional but follow complex trajectories over space and time, driven by changing anthropogenic and abiotic conditions. We present a multi-observational approach to land-change analysis that addresses the complex geographic and temporal variability of vegetation changes related to climate and land use. Using land-ownership data as a proxy for land-use practices, multitemporal land-cover maps, and repeat photography dating to the late 19th century, we examine changing spatial and temporal distributions of two vegetation types with high conservation value in the southwestern United States: grasslands and riparian vegetation. In contrast to many reported vegetation changes, notably shrub encroachment in desert grasslands, we found an overall increase in grassland area and decline of xeroriparian and riparian vegetation. These observed change patterns were neither temporally directional nor spatially uniform over the landscape. Historical data suggest that long-term vegetation changes coincide with broad climate fluctuations while fine-scale patterns are determined by land-management practices. In some cases, restoration and active management appear to weaken the effects of climate on vegetation; therefore, if land managers in this region act in accord with on-going directional changes, the current drought and associated ecological reorganization may provide an opportunity to achieve desired restoration endpoints.

CFD Prediction of the Temperature Distribution within a Refrigerated Truck Filled with Fruit and Vegetables during Transport

NASA Astrophysics Data System (ADS)

Konishi, Yoshihiro; Tanaka, Fumihiko; Uchino, Toshitaka; Hamanaka, Daisuke

During transport using refrigerated trucks, the maintaining of the recommended conditions throughout a cargo is required to preserve the quality of fresh fruit and vegetables. Temperature distribution within a refrigerated container is governed by airflow pattern with thermal transport. In this study, Computational Fluid Dynamics(CFD) predictions were used to investigate the temperature distribution within a typical refrigerated truck filled with cardboard packed eggplants. Numerical modeling of heat and mass transfer was performed using the CFX code. In order to verify the developed CFD model full-scale measurement was carried out within a load of eggplants during transport. CFD predictions show reasonable agreement with actual data.

Longleaf Pine Ground-Layer Vegetation in Francis Marion National Forest: Reintroduction, Restoration, and Vegetation Assembly

DOE Office of Scientific and Technical Information (OSTI.GOV)

Glitzenstein, J.; Streng, D.; Wade, D.

2001-01-01

Study represents significant progress in understanding of compositional gradients in longleaf pine plant communities of Central South Carolina. Study shows the importance of water table depths as a controlling variable with vegetation patterns in the field and similar effects in a garden experiment. Grass planting study suggests that observed field distributions of dormant pine savannah grasses derive from complex interactive effects of fire history, hydrology and light environments. Use of regional longleaf data set to identify candidate species for introduction also appears to be a pioneering effort.

Environmental drivers of spatial patterns of topsoil nitrogen and phosphorus under monsoon conditions in a complex terrain of South Korea

PubMed Central

Choi, Kwanghun; Spohn, Marie; Park, Soo Jin; Huwe, Bernd; Ließ, Mareike

2017-01-01

Nitrogen (N) and phosphorus (P) in topsoils are critical for plant nutrition. Relatively little is known about the spatial patterns of N and P in the organic layer of mountainous landscapes. Therefore, the spatial distributions of N and P in both the organic layer and the A horizon were analyzed using a light detection and ranging (LiDAR) digital elevation model and vegetation metrics. The objective of the study was to analyze the effect of vegetation and topography on the spatial patterns of N and P in a small watershed covered by forest in South Korea. Soil samples were collected using the conditioned latin hypercube method. LiDAR vegetation metrics, the normalized difference vegetation index (NDVI), and terrain parameters were derived as predictors. Spatial explicit predictions of N/P ratios were obtained using a random forest with uncertainty analysis. We tested different strategies of model validation (repeated 2-fold to 20-fold and leave-one-out cross validation). Repeated 10-fold cross validation was selected for model validation due to the comparatively high accuracy and low variance of prediction. Surface curvature was the best predictor of P contents in the organic layer and in the A horizon, while LiDAR vegetation metrics and NDVI were important predictors of N in the organic layer. N/P ratios increased with surface curvature and were higher on the convex upper slope than on the concave lower slope. This was due to P enrichment of the soil on the lower slope and a more even spatial distribution of N. Our digital soil maps showed that the topsoils on the upper slopes contained relatively little P. These findings are critical for understanding N and P dynamics in mountainous ecosystems. PMID:28837590

Human alterations, dynamic equilibrium, and riparian ecosystem responses along selected rivers in Tuscany, Italy (Invited)

NASA Astrophysics Data System (ADS)

Hupp, C. R.; Rinaldi, M.

2010-12-01

Many, if not most, streams have been mildly to severely affected by human disturbance, which complicates efforts to understand riparian ecosystems. Mediterranean regions have a long history of human influences including: dams, stream channelization, mining of sediment, and levee /canal construction. Typically these alterations reduce the ecosystem services that functioning floodplains provide and may negatively impact the natural ecology of floodplains through reductions in suitable habitats, biodiversity, and nutrient cycling. Additionally, human alterations typically shift affected streams away from a state of natural dynamic equilibrium, where net sediment deposition is approximately in balance with net erosion. Lack of equilibrium typically affects the degree to which floodplain ecosystems are connected to streamflow regime. Low connectivity, usually from human- or climate-induced incision, may result in reduced flow on floodplains and lowered water tables. High connectivity may result in severe sediment deposition. Connectivity has a direct impact on vegetation communities. Riparian vegetation distribution patterns and diversity relative to various fluvial geomorphic channel patterns, landforms, and processes are described and interpreted for selected rivers of Tuscany, Central Italy; with emphasis on channel evolution following human impacts. Multivariate analysis reveals distinct quantitative vegetation patterns related to six fluvial geomorphic surfaces. Analysis of vegetation data also shows distinct associations of plants with adjustment processes related to the stage of channel evolution. Plant distribution patterns coincide with disturbance/landform/soil moisture gradients. Species richness increases from channel bed to terrace and on heterogeneous riparian areas, while species richness decreases from moderate to intense incision and from low to intense narrowing. As a feedback mechanism, woody vegetation in particular may facilitate geomorphic recovery of floodplains by affecting sedimentation dynamics. Identification and understanding of critical fluvial parameters related to floodplain connectivity (e.g. stream gradient, grain-size, and hydrography) and spatial and temporal sediment deposition/erosion process trajectories should facilitate management efforts to retain and/or regain important ecosystem services.

Imaging polarimetry of forest canopies: how the azimuth direction of the sun, occluded by vegetation, can be assessed from the polarization pattern of the sunlit foliage

NASA Astrophysics Data System (ADS)

Hegedüs, Ramón; Barta, András; Bernáth, Balázs; Benno Meyer-Rochow, Victor; Horváth, Gábor

2007-08-01

Radiance, color, and polarization of the light in forests combine to create complex optical patterns. Earlier sporadic polarimetric studies in forests were limited by the narrow fields of view of the polarimeters used in such studies. Since polarization patterns in the entire upper hemisphere of the visual environment of forests could be important for forest-inhabiting animals that make use of linearly polarized light for orientation, we measured 180° field-of-view polarization distributions in Finnish forests. From a hot air balloon we also measured the polarization patterns of Hungarian grasslands lit by the rising sun. We found that the pattern of the angle of polarization α of sunlit grasslands and sunlit tree canopies was qualitatively the same as that of the sky. We show here that contrary to an earlier assumption, the α-pattern characteristic of the sky always remains visible underneath overhead vegetation, independently of the solar elevation and the sky conditions (clear or partly cloudy with visible sun's disc), provided the foliage is sunlit and not only when large patches of the clear sky are visible through the vegetation. Since the mirror symmetry axis of the α-pattern of the sunlit foliage is the solar-antisolar meridian, the azimuth direction of the sun, occluded by vegetation, can be assessed in forests from this polarization pattern. Possible consequences of this robust polarization feature of the optical environment in forests are briefly discussed with regard to polarization-based animal navigation.

Understanding the role of wildland fire, insects, and disease in predicting climate change effects on whitebark pine: Simulating vegetation, disturbance, and climate dynamics in a northern Rocky Mountain landscape

Treesearch

Robert Keane; Rachel Loehman

2010-01-01

Climate changes are projected to profoundly influence vegetation patterns and community compositions, either directly through increased species mortality and shifts in species distributions, or indirectly through disturbance dynamics such as increased wildfire activity and extent, shifting fire regimes, and pathogenesis. High-elevation landscapes have been shown to be...

Plant distribution and stand characteristics in brackish marshes: Unravelling the roles of abiotic factors and interspecific competition

NASA Astrophysics Data System (ADS)

Carus, Jana; Heuner, Maike; Paul, Maike; Schröder, Boris

2017-09-01

Due to increasing pressure on estuarine marshes from sea level rise and river training, there is a growing need to understand how species-environment relationships influence the zonation and growth of tidal marsh vegetation. In the present study, we investigated the distribution and stand characteristics of the two key brackish marsh species Bolboschoenus maritimus and Phragmites australis in the Elbe estuary together with several abiotic habitat factors. We then tested the effect of these habitat factors on plant growth and zonation with generalised linear models (GLMs). Our study provides detailed information on the importance of single habitat factors and their interactions for controlling the distribution patterns and stand characteristics of two key marsh species. Our results suggest that flow velocity is the main factor influencing species distribution and stand characteristics and together with soil-water salinity even affects the inundation tolerance of the two specie investigated here. Additionally, inundation height and duration as well as interspecific competition helped explain the distribution patterns and stand characteristics. By identifying the drivers of marsh zonation and stand characteristics and quantifying their effects, this study provides useful information for evaluating a future contribution of tidal marsh vegetation to ecosystem-based shore protection.

The Contribution of Vegetation and Landscape Configuration for Predicting Environmental Change Impacts on Iberian Birds

PubMed Central

Triviño, Maria; Thuiller, Wilfried; Cabeza, Mar; Hickler, Thomas; Araújo, Miguel B.

2011-01-01

Although climate is known to be one of the key factors determining animal species distributions amongst others, projections of global change impacts on their distributions often rely on bioclimatic envelope models. Vegetation structure and landscape configuration are also key determinants of distributions, but they are rarely considered in such assessments. We explore the consequences of using simulated vegetation structure and composition as well as its associated landscape configuration in models projecting global change effects on Iberian bird species distributions. Both present-day and future distributions were modelled for 168 bird species using two ensemble forecasting methods: Random Forests (RF) and Boosted Regression Trees (BRT). For each species, several models were created, differing in the predictor variables used (climate, vegetation, and landscape configuration). Discrimination ability of each model in the present-day was then tested with four commonly used evaluation methods (AUC, TSS, specificity and sensitivity). The different sets of predictor variables yielded similar spatial patterns for well-modelled species, but the future projections diverged for poorly-modelled species. Models using all predictor variables were not significantly better than models fitted with climate variables alone for ca. 50% of the cases. Moreover, models fitted with climate data were always better than models fitted with landscape configuration variables, and vegetation variables were found to correlate with bird species distributions in 26–40% of the cases with BRT, and in 1–18% of the cases with RF. We conclude that improvements from including vegetation and its landscape configuration variables in comparison with climate only variables might not always be as great as expected for future projections of Iberian bird species. PMID:22216263

Water use patterns of estuarine vegetation in a tidal creek system.

PubMed

Wei, Lili; Lockington, David A; Poh, Seng-Chee; Gasparon, Massimo; Lovelock, Catherine E

2013-06-01

Water availability is a key determinant of the zonation patterns in estuarine vegetation, but water availability and the use of different water sources over space and time are not well understood. We have determined the seasonal water use patterns of riparian vegetation over an estuarine ecotone. Our aim was to investigate how the water use patterns of estuarine vegetation respond to variations in the availability of tidal creek water and rain-derived freshwater. The levels of natural stable isotopes of oxygen and hydrogen were assessed in the stem of the mangrove Avicennia marina (tall and scrub growth forms), Casuarina glauca and Melaleuca quinquenervia that were distributed along transects from river/creek-front towards inland habitats. The isotopic composition of plant tissues and the potential water sources were assessed in both the wet season, when freshwater from rainfall is present, and the dry season, when mangrove trees are expected to be more dependent on tidal water, and when Casuarina and Melaleuca are expected to be dependent on groundwater. Our results indicate that rainwater during the wet season contributes significantly to estuarine vegetation, even to creek-side mangroves which are inundated by tidal creek water daily, and that estuarine vegetation depends primarily on freshwater throughout the year. In contrast, high intertidal scrub mangroves were found to use the greatest proportion of tidal creek water, supplemented by groundwater in the dry season. Contrary to prediction, inland trees C. glauca and M. quinquenervia were found also to rely predominantly on rainwater--even in the dry season. The results of this study reveal a high level of complexity in vegetation water use in estuarine settings.

[Vegetation spatial and temporal dynamic characteristics based on NDVI time series trajectories in grassland opencast coal mining].

PubMed

Jia, Duo; Wang, Cang Jiao; Mu, Shou Guo; Zhao, Hua

2017-06-18

The spatiotemporal dynamic patterns of vegetation in mining area are still unclear. This study utilized time series trajectory segmentation algorithm to fit Landsat NDVI time series which generated from fusion images at the most prosperous period of growth based on ESTARFM algorithm. Combining with the shape features of the fitted trajectory, this paper extracted five vegetation dynamic patterns including pre-disturbance type, continuous disturbance type, stabilization after disturbance type, stabilization between disturbance and recovery type, and recovery after disturbance type. The result indicated that recovery after disturbance type was the dominant vegetation change pattern among the five types of vegetation dynamic pattern, which accounted for 55.2% of the total number of pixels. The follows were stabilization after disturbance type and continuous disturbance type, accounting for 25.6% and 11.0%, respectively. The pre-disturbance type and stabilization between disturbance and recovery type accounted for 3.5% and 4.7%, respectively. Vegetation disturbance mainly occurred from 2004 to 2009 in Shengli mining area. The onset time of stable state was 2008 and the spatial locations mainlydistributed in open-pit stope and waste dump. The reco-very state mainly started since the year of 2008 and 2010, while the areas were small and mainly distributed at the periphery of open-pit stope and waste dump. Duration of disturbance was mainly 1 year. The duration of stable period usually sustained 7 years. The duration of recovery state of the type of stabilization between disturbances continued 2 to 5 years, while the type of recovery after disturbance often sustained 8 years.

Diversity and Spatial-Temporal Distribution of Soil Macrofauna Communities Along Elevation in the Changbai Mountain, China.

PubMed

Yin, Xiuqin; Qiu, Lili; Jiang, Yunfeng; Wang, Yeqiao

2017-06-01

The understanding of patterns of vertical variation and diversity of flora and fauna along elevational change has been well established over the past century. However, it is unclear whether there is an elevational distribution pattern for soil fauna. This study revealed the diversity and spatial-temporal distribution of soil macrofauna communities in different vegetation zones from forest to alpine tundra along elevation of the Changbai Mountain, China. The abundance, richness, and Shannon-Wiener diversity index of soil macrofauna communities were compared in four distinguished vegetation zones including the coniferous and broadleaved mixed forest zone, the coniferous forest zone, the subalpine dwarf birch (Betula ermanii) forest zone, and the alpine tundra zone. Soil macrofauna were extracted in May, July, and September of 2009. In each season, the abundance and richness of the soil macrofauna decreased with the ascending elevation. The Shannon-Wiener diversity indices of the soil macrofauna were higher in the vegetation zones of lower elevation than of higher elevation. Significant differences were observed in the abundance, richness, and Shannon-Wiener diversity index for the studied vegetation zones. Soil macrofauna congregated mainly to the litter layer in the low-elevation areas and in the 0-5 cm soil layer of the higher elevation areas. The results emphasized that the diversity of soil macrofauna communities decreased as the elevation increased and possess the distinct characteristics of zonation in the mountain ecosystem. The diversity and distribution of soil macrofauna communities were influenced by mean annual precipitation, altitude, annual radiation quantity, and mean annual temperature. © The Authors 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Effect of grazing on vegetation and soil of the heuweltjieveld in the Succulent Karoo, South Africa

NASA Astrophysics Data System (ADS)

Schmiedel, Ute; Röwer, Inga Ute; Luther-Mosebach, Jona; Dengler, Jürgen; Oldeland, Jens; Gröngröft, Alexander

2016-11-01

We asked how historical and recent grazing intensity affect the patchy landscape of the heuweltjieveld in the semi-arid biodiversity hotspot Succulent Karoo. The study was carried out on a communal farmland 80 km south-west of Springbok, in Namaqualand. Heuweltjies are roughly circular earth mounds that are regularly distributed in this landscape. We sampled plant species and life-form composition, diversity measures, habitat and soil variables in 100 m2 plots, placed in three visually distinguishable heuweltjie zones (centre, fringe, and matrix) and distributed across grazing camps with different recent and historic grazing intensities. Differences between heuweltjie zones were assessed with ANOVAs and multiple linear regressions. The effect of past and recent grazing intensity on soil and plant variables was analysed by Generalized Linear Models for each heuweltjie zone separately. The three zones constituted clearly distinguishable units in terms of vegetation and soil characteristics. Soil pH and cover of annual plants increased from matrix to centres, while total vegetation cover, species richness and perennial plant cover decreased in the same direction. Historic (pre-2000) grazing patterns had the strongest effects on fringes, showing the strongest soil and vegetation-related signs of overutilization with increased stocking density. Centres showed signs of overutilization irrespective of the stocking density. The much shorter exposure to recent grazing pattern (post-2000), which was nearly inverse to the historic grazing pattern, showed increase of vegetation cover (centres) and species richness (matrix) with recent grazing intensity. We interpret these effects as still visible responses of the lower grazing intensity in these camps during the historic period. No recovery under recent grazing was observed at any of the zones. We conclude that irrespective of their conducive growing conditions, once transformed to a disturbed state, heuweltjie centres recover slowly, whereas the less impacted soil and vegetation of fringes are more responsive than centres and matrix.

Moving Uphill: Microbial Facilitation at the Leading Edge of Plant Species Distributional Shifts

NASA Astrophysics Data System (ADS)

Suding, K.; Farrer, E.; Spasojevic, M.; Porazinska, D.; Bueno de Mesquita, C.; Schmidt, S. K.

2016-12-01

Climate change is expected to influence species distributions and reshuffle patterns of biodiversity. A key challenge to our understanding of these effects is that biotic interactions - new species to compete with, new stressors that increase dependence on facilitation, new prey or predators - will likely affect the ability of species to track climate at the leading edges of their distributional range. While it is well established that soil biota strongly influence plant abundance and diversity, it has been difficult to quantify the key belowground dynamics. This presentation will investigate the influence of one key biotic interaction, between plants and soil microbiota, on the ability of plant species to track climate change and expand their range uphill in a high montane system in the Front Range of Colorado. High-resolution photography from 1972 and 2008 indicate colonization of tundra vegetation in formerly unvegetated areas. Observational work on the distributions patterns of both plants and soil microbiota (bacteria, fungi and nematodes) in a spatially-explicit grid at the upper edge of plant distributions indicate strong, mostly positive, associations between plant species and soil taxa. Abiotic factors, while important, consistently underpredicted the occurrence of plant species and, in nine of the 12 most common tundra plants, co-occurring microbial taxa were important predictors of plant occurrence. Comparison of plant and microbial distributional patterns in 2007 and 2015 indicate the influence of microbial community composition on assembly and beta-diversity of the plant community over time. Plant colonization patterns in this region previously devoid of vegetation will likely influence carbon, nitrogen and phosphorus dynamics, with downstream consequences on nutrient limitation and phytoplankton composition in alpine lakes.

Environmental factors explaining the vegetation patterns in a temperate peatland.

PubMed

Pellerin, Stéphanie; Lagneau, Louis-Adrien; Lavoie, Martin; Larocque, Marie

2009-08-01

Although ombrotrophic temperate peatlands are important ecosystems for maintaining biodiversity in eastern North America, the environmental factors influencing their flora are only partly understood. The relationships between plant species distribution and environmental factors were thus studied within the oldest temperate peatland of Québec. Plant assemblages were identified by cluster analysis while CCA was used to related vegetation gradients to environmental factors. Five assemblages were identified; three typical of open bog and two characterized by more minerotrophic vegetation. Thicker peat deposit was encounter underlying the bog assemblages while higher water table level and percentage of free surface water distinguished the minerotrophic assemblages. Overall, the floristic patterns observed were spatially structured along the margins and the expanse. The most important environmental factors explaining this spatial gradient were the percentage of free surface water and the highest water-table level.

Legume Diversity Patterns in West Central Africa: Influence of Species Biology on Distribution Models

PubMed Central

de la Estrella, Manuel; Mateo, Rubén G.; Wieringa, Jan J.; Mackinder, Barbara; Muñoz, Jesús

2012-01-01

Objectives Species Distribution Models (SDMs) are used to produce predictions of potential Leguminosae diversity in West Central Africa. Those predictions are evaluated subsequently using expert opinion. The established methodology of combining all SDMs is refined to assess species diversity within five defined vegetation types. Potential species diversity is thus predicted for each vegetation type respectively. The primary aim of the new methodology is to define, in more detail, areas of species richness for conservation planning. Methodology Using Maxent, SDMs based on a suite of 14 environmental predictors were generated for 185 West Central African Leguminosae species, each categorised according to one of five vegetation types: Afromontane, coastal, non-flooded forest, open formations, or riverine forest. The relative contribution of each environmental variable was compared between different vegetation types using a nonparametric Kruskal-Wallis analysis followed by a post-hoc Kruskal-Wallis Paired Comparison contrast. Legume species diversity patterns were explored initially using the typical method of stacking all SDMs. Subsequently, five different ensemble models were generated by partitioning SDMs according to vegetation category. Ecological modelers worked with legume specialists to improve data integrity and integrate expert opinion in the interpretation of individual species models and potential species richness predictions for different vegetation types. Results/Conclusions Of the 14 environmental predictors used, five showed no difference in their relative contribution to the different vegetation models. Of the nine discriminating variables, the majority were related to temperature variation. The set of variables that played a major role in the Afromontane species diversity model differed significantly from the sets of variables of greatest relative important in other vegetation categories. The traditional approach of stacking all SDMs indicated overall centers of diversity in the region but the maps indicating potential species richness by vegetation type offered more detailed information on which conservation efforts can be focused. PMID:22911808

Shifts in wind energy potential following land-use driven vegetation dynamics in complex terrain.

PubMed

Fang, Jiannong; Peringer, Alexander; Stupariu, Mihai-Sorin; Pǎtru-Stupariu, Ileana; Buttler, Alexandre; Golay, Francois; Porté-Agel, Fernando

2018-10-15

Many mountainous regions with high wind energy potential are characterized by multi-scale variabilities of vegetation in both spatial and time dimensions, which strongly affect the spatial distribution of wind resource and its time evolution. To this end, we developed a coupled interdisciplinary modeling framework capable of assessing the shifts in wind energy potential following land-use driven vegetation dynamics in complex mountain terrain. It was applied to a case study area in the Romanian Carpathians. The results show that the overall shifts in wind energy potential following the changes of vegetation pattern due to different land-use policies can be dramatic. This suggests that the planning of wind energy project should be integrated with the land-use planning at a specific site to ensure that the expected energy production of the planned wind farm can be reached over its entire lifetime. Moreover, the changes in the spatial distribution of wind and turbulence under different scenarios of land-use are complex, and they must be taken into account in the micro-siting of wind turbines to maximize wind energy production and minimize fatigue loads (and associated maintenance costs). The proposed new modeling framework offers, for the first time, a powerful tool for assessing long-term variability in local wind energy potential that emerges from land-use change driven vegetation dynamics over complex terrain. Following a previously unexplored pathway of cause-effect relationships, it demonstrates a new linkage of agro- and forest policies in landscape development with an ultimate trade-off between renewable energy production and biodiversity targets. Moreover, it can be extended to study the potential effects of micro-climatic changes associated with wind farms on vegetation development (growth and patterning), which could in turn have a long-term feedback effect on wind resource distribution in mountainous regions. Copyright © 2018 Elsevier B.V. All rights reserved.

Forage quantity estimation from MERIS using band depth parameters

NASA Astrophysics Data System (ADS)

Ullah, Saleem; Yali, Si; Schlerf, Martin

Saleem Ullah1 , Si Yali1 , Martin Schlerf1 Forage quantity is an important factor influencing feeding pattern and distribution of wildlife. The main objective of this study was to evaluate the predictive performance of vegetation indices and band depth analysis parameters for estimation of green biomass using MERIS data. Green biomass was best predicted by NBDI (normalized band depth index) and yielded a calibration R2 of 0.73 and an accuracy (independent validation dataset, n=30) of 136.2 g/m2 (47 % of the measured mean) compared to a much lower accuracy obtained by soil adjusted vegetation index SAVI (444.6 g/m2, 154 % of the mean) and by other vegetation indices. This study will contribute to map and monitor foliar biomass over the year at regional scale which intern can aid the understanding of bird migration pattern. Keywords: Biomass, Nitrogen density, Nitrogen concentration, Vegetation indices, Band depth analysis parameters 1 Faculty of Geo-Information Science and Earth Observation (ITC), University of Twente, The Netherlands

[Spatial pattern of sub-alpine forest restoration in west Sichuan].

PubMed

Zhang, Yuandong; Liu, Shirong; Zhao, Changming

2005-09-01

West Sichuan sub-alpine is an extension of Qinghai-Tibet Plateau to southeast China, which is covered mainly with dark coniferous forest. As a result of long-term large scale over-logging, the forests have been greatly reduced and degraded. Nowadays, the forest restoration and regeneration in the region are being highlighted. Selecting Miyaluo as a case study area and employing the methods of plot investigation, ETM image interpretation, and overlaying vegetation map with digital topography, this paper analyzed the relations between the appearance and origin of four forest vegetation types, along with their topography differentiation and spatial patterns after a large scale logging and regeneration. The results showed that the appearance of forest vegetations was significantly correlated with their origin. Old coniferous forests (OC) were primitive ones, middle-aged and young coniferous forests (MYC) were from artificial regeneration, deciduous broadleaf forests (DB) were natural secondary ones, while mixed coniferous and deciduous forests (MCD) were partly from natural secondary ones and others from the conjunct action of artificial and natural regeneration. The main cut area in Miyaluo located in the sites with elevation from 2 800 to 3 600 m, where forest restoration appeared difference among different aspects. MYC was mainly distributed on sunny and half-sunny slope, DB and MCD were distributed on shady and half-shady slope, and OC were reserved on the sites with elevation more than 3 600 m. In the process of forest restoration, the four forest vegetation types were in mosaic pattern, and the landscape was seriously fragmentized.

Spatial-temporal Evolution of Vegetation Coverage and Analysis of it’s Future Trends in Wujiang River Basin

NASA Astrophysics Data System (ADS)

Xiao, Jianyong; Bai, Xiaoyong; Zhou, Dequan; Qian, Qinghuan; Zeng, Cheng; Chen, Fei

2018-01-01

Vegetation coverage dynamics is affected by climatic, topography and human activities, which is an important indicator reflecting the regional ecological environment. Revealing the spatial-temporal characteristics of vegetation coverage is of great significance to the protection and management of ecological environment. Based on MODIS NDVI data and the Maximum Value Composites (MVC), we excluded soil spectrum interference to calculate Fractional Vegetation Coverage (FVC). Then the long-term FVC was used to calculate the spatial pattern and temporal variation of vegetation in Wujiang River Basin from 2000 to 2016 by using Trend analysis and Hurst index. The relationship between topography and spatial distribution of FVC was analyzed. The main conclusions are as follows: (1) The multi-annual mean vegetation coverage reveals a spatial distribution variation characteristic of low value in midstream and high level in other parts of the basin, owing a mean value of 0.6567. (2) From 2000 to 2016, the FVC of the Wujiang River Basin fluctuated between 0.6110 and 0.7380, and the overall growth rate of FVC was 0.0074/a. (3) The area of vegetation coverage tending to improve is more than that going to degrade in the future. Grass land, Arable land and Others improved significantly; karst rocky desertification comprehensive management project lead to persistent vegetation coverage improvement of Grass land, Arable land and Others. Residential land is covered with obviously degraded vegetation, resulting of urban sprawl; (4) The spatial distribution of FVC is positively correlated with TNI. Researches of spatial-temporal evolution of vegetation coverage have significant meaning for the ecological environment protection and management of the Wujiang River Basin.

Dynamic vegetation modeling of tropical biomes during Heinrich events

NASA Astrophysics Data System (ADS)

Handiani, Dian Noor; Paul, André; Dupont, Lydie M.

2010-05-01

Heinrich events are thought to be associated with a slowdown of the Atlantic Meridional Overturning Circulation (AMOC), which in turn would lead to a cooling of the North Atlantic Ocean and a warming of the South Atlantic Ocean (the "bipolar seesaw" hypothesis). The accompanying abrupt climate changes occurred not only in the ocean but also on the continents. Changes were strongest in the Northern Hemisphere but were registered in the tropics as well. Pollen data from Angola and Brazil showed that climate changes during Heinrich events affected vegetation patterns very differently in eastern South America and western Africa. To understand the differential response in the terrestrial tropics, we studied the vegetation changes during Heinrich events by using a dynamic global vegetation model (TRIFFID) as part of the University of Victoria (UVic) Earth System-Climate Model (ESCM). The model results show a bipolar seesaw pattern in temperature and precipitation during a near-collapse of the AMOC. The succession in plant-functional types (PFTs) showed changes from forest to shrubs to desert, including spreading desert in northwest Africa, retreating broadleaf trees in West Africa and northern South America, but advancing broadleaf trees in Brazil. The pattern is explained by a southward shift of the tropical rainbelt resulting in a strong decrease in precipitation over northwest and West Africa as well as in northern South America, but an increase in precipitation in eastern Brazil. To facilitate the comparison between modeled vegetation results with pollen data, we diagnosed the distribution of biomes from the PFT coverage and the simulated model climate. The biome distribution was computed for Heinrich event 1 and the Last Glacial Maximum as well as for pre-industrial conditions. We used a classification of biomes in terms of "mega-biomes", which were defined following a scheme originally proposed by BIOME 6000 (v 4.2). The biome distribution of the Sahel region changed from warm temperate forest during the last glacial maximum to the grassland and dry shrubland, suggesting a drier climate during Heinrich event 1. In south-western Africa savanna and dry woodland changed into boreal forest and boreal-temperate forest suggesting wetter conditions. The biomes diagnosed from the control-run, were compared to the modern vegetation reconstruction of BIOME 4 (http://www.bridge.bris.ac.uk/resources/Databases/BIOMES_data). Consistent biome patterns were simulated for the tropical forests of western and south-western Africa and the grasslands of northern Africa. On the other hand, in southern Europe, where the BIOME 4 vegetation reconstruction is dominated by warm temperate and temperate forest, our model shows a strong bias towards the grassland.

[Seasonal dynamics and vertical distribution pattern of bud bank in different erosion environments on hilly-gully Loess Plateau of Northwest China].

PubMed

Du, Hua-Dong; Jiao, Ju-Ying; Kou, Meng; Wang, Ning

2013-05-01

This paper studied the vegetation composition, bud composition, and the seasonal dynamics and vertical distribution pattern of bud bank in five erosion environments (sunny gully slope, sunny hilly slope, hilltop, shady hilly slope, and shady gully slope) on the hilly-gully Loess Plateau of North Shaanxi. In the study area, the perennial species with perennial bud bank accounted for 80.3% of the total species, while the annual species with seasonal bud bank took up 19.7% of the total. In vegetation turning-green season, there was a relatively large perennial bud bank stock on the sunny hilly-gully slope where serious erosion occurred, while seasonal bud bank showed a higher bud bank density in blossom and fruit-setting season on the hilltop and two shady slopes where soil erosion intensity was relatively gentle. The proportion of underground bud bank to total perennial bud bank in different erosion environments was relatively stable. On the land surface, the perennial bud bank stock was larger on the sunny slope where the soil disturbance often occurred, whereas the seasonal bud bank stock was larger on the shady slope and hilltop. Due to the different species composition of plant communities in different erosion environments, in addition to the disturbance of soil erosion and the seasonal plant regeneration, the seasonal dynamics and vertical distribution pattern of bud bank changed. It was suggested that bud bank played an important role in the vegetation regeneration after the disturbance of soil erosion on the hilly-gully Loess Plateau of North Shaanxi.

Topographic influences on vegetation mosaics and tree diversity in the Chihuahuan Desert Borderlands.

PubMed

Poulos, Helen M; Camp, Ann E

2010-04-01

The abundance and distribution of species reflect how the niche requirements of species and the dynamics of populations interact with spatial and temporal variation in the environment. This study investigated the influence of geographical variation in environmental site conditions on tree dominance and diversity patterns in three topographically dissected mountain ranges in west Texas, USA, and northern Mexico. We measured tree abundance and basal area using a systematic sampling design across the forested areas of three mountain ranges and related these data to a suite of environmental parameters derived from field and digital elevation model data. We employed cluster analysis, classification and regression trees (CART), and rarefaction to identify (1) the dominant forest cover types across the three study sites and (2) environmental influences on tree distribution and diversity patterns. Elevation, topographic position, and incident solar radiation were the major influences on tree dominance and diversity. Mesic valley bottoms hosted high-diversity vegetation types, while hotter and drier mid-slopes and ridgetops supported lower tree diversity. Valley bottoms and other topographic positions shared few species, indicating high species turnover at the landscape scale. Mountain ranges with high topographic complexity also had higher species richness, suggesting that geographical variability in environmental conditions was a major influence on tree diversity. This study stressed the importance of landscape- and regional-scale topographic variability as a key factor controlling vegetation pattern and diversity in southwestern North America.

Distribution and food habits of young-of-the-year fishes in a backwater lake of the upper Mississippi River

USGS Publications Warehouse

Holland, L.E.; Huston, M.L.

1985-01-01

The distribution patterns and food habits of young-of-the-year (YOY) fishes in a lentic area adjacent to the main channel of Pool 7 of the upper Mississippi River were studied. Habitats sampled grouped distinctly based on percent composition and abundance of YOY fishes with those having submergent vegetation dominated by a number of important sport species. In late spring, the grouping of stations depended on the presence or absence of newly transformed northern pike (Esox lucius). In early summer, stations did not differ as distinctly in composition, but in total abundance of young. Those stations with submergent vegetation had total catches which were more than double those elsewhere. By late summer, submergent and mixed vegetation stations formed a distinct assemblage influenced by the preponderance of three species of sunfishes. (DBO).

LPJ-GUESS Simulated North America Vegetation for 21-0 ka Using the TraCE-21ka Climate Simulation

NASA Astrophysics Data System (ADS)

Shafer, S. L.; Bartlein, P. J.

2016-12-01

Transient climate simulations that span multiple millennia (e.g., TraCE-21ka) have become more common as computing power has increased, allowing climate models to complete long simulations in relatively short periods of time (i.e., months). These climate simulations provide information on the potential rate, variability, and spatial expression of past climate changes. They also can be used as input data for other environmental models to simulate transient changes for different components of paleoenvironmental systems, such as vegetation. Long, transient paleovegetation simulations can provide information on a range of ecological processes, describe the spatial and temporal patterns of changes in species distributions, and identify the potential locations of past species refugia. Paleovegetation simulations also can be used to fill in spatial and temporal gaps in observed paleovegetation data (e.g., pollen records from lake sediments) and to test hypotheses of past vegetation change. We used the TraCE-21ka transient climate simulation for 21-0 ka from CCSM3, a coupled atmosphere-ocean general circulation model. The TraCE-21ka simulated temperature, precipitation, and cloud data were regridded onto a 10-minute grid of North America. These regridded climate data, along with soil data and atmospheric carbon dioxide concentrations, were used as input to LPJ-GUESS, a general ecosystem model, to simulate North America vegetation from 21-0 ka. LPJ-GUESS simulates many of the processes controlling the distribution of vegetation (e.g., competition), although some important processes (e.g., dispersal) are not simulated. We evaluate the LPJ-GUESS-simulated vegetation (in the form of plant functional types and biomes) for key time periods and compare the simulated vegetation with observed paleovegetation data, such as data archived in the Neotoma Paleoecology Database. In general, vegetation simulated by LPJ-GUESS reproduces the major North America vegetation patterns (e.g., forest, grassland) with regional areas of disagreement between simulated and observed vegetation. We describe the regions and time periods with the greatest data-model agreement and disagreement, and discuss some of the strengths and weaknesses of both the simulated climate and simulated vegetation data.

Projected Future Vegetation Changes for the Northwest United States and Southwest Canada at a Fine Spatial Resolution Using a Dynamic Global Vegetation Model.

PubMed

Shafer, Sarah L; Bartlein, Patrick J; Gray, Elizabeth M; Pelltier, Richard T

2015-01-01

Future climate change may significantly alter the distributions of many plant taxa. The effects of climate change may be particularly large in mountainous regions where climate can vary significantly with elevation. Understanding potential future vegetation changes in these regions requires methods that can resolve vegetation responses to climate change at fine spatial resolutions. We used LPJ, a dynamic global vegetation model, to assess potential future vegetation changes for a large topographically complex area of the northwest United States and southwest Canada (38.0-58.0°N latitude by 136.6-103.0°W longitude). LPJ is a process-based vegetation model that mechanistically simulates the effect of changing climate and atmospheric CO2 concentrations on vegetation. It was developed and has been mostly applied at spatial resolutions of 10-minutes or coarser. In this study, we used LPJ at a 30-second (~1-km) spatial resolution to simulate potential vegetation changes for 2070-2099. LPJ was run using downscaled future climate simulations from five coupled atmosphere-ocean general circulation models (CCSM3, CGCM3.1(T47), GISS-ER, MIROC3.2(medres), UKMO-HadCM3) produced using the A2 greenhouse gases emissions scenario. Under projected future climate and atmospheric CO2 concentrations, the simulated vegetation changes result in the contraction of alpine, shrub-steppe, and xeric shrub vegetation across the study area and the expansion of woodland and forest vegetation. Large areas of maritime cool forest and cold forest are simulated to persist under projected future conditions. The fine spatial-scale vegetation simulations resolve patterns of vegetation change that are not visible at coarser resolutions and these fine-scale patterns are particularly important for understanding potential future vegetation changes in topographically complex areas.

Land surface phenological responses to land use and climate variation in a changing Central Asia

NASA Astrophysics Data System (ADS)

Kariyeva, Jahan

During the last few decades Central Asia has experienced widespread changes in land cover and land use following the socio-economic and institutional transformations of the region catalyzed by the USSR collapse in 1991. The decade-long drought events and steadily increasing temperature regimes in the region came on top of these institutional transformations, affecting the long term and landscape scale vegetation responses. This research is based on the need to better understand the potential ecological and policy implications of climate variation and land use practices in the contexts of landscape-scale changes dynamics and variability patterns of land surface phenology responses in Central Asia. The land surface phenology responses -- the spatio-temporal dynamics of terrestrial vegetation derived from the remotely sensed data -- provide measurements linked to the timing of vegetation growth cycles (e.g., start of growing season) and total vegetation productivity over the growing season, which are used as a proxy for the assessment of effects of variations in environmental settings. Local and regional scale assessment of the before and after the USSR collapse vegetation response patterns in the natural and agricultural systems of the Central Asian drylands was conducted to characterize newly emerging links (since 1991) between coupled human and natural systems, e.g., socio-economic and policy drivers of altered land and water use and distribution patterns. Spatio-temporal patterns of bioclimatic responses were examined to determine how phenology is associated with temperature and precipitation in different land use types, including rainfed and irrigated agricultural types. Phenological models were developed to examine relationship between environmental drivers and effect of their altitudinal and latitudinal gradients on the broad-scale vegetation response patterns in non-cropland ecosystems of the desert, steppe, and mountainous regional landscapes of Central Asia. The study results demonstrated that the satellite derived measurements of temporal cycles of vegetation greenness and productivity data was a valuable bioclimatic integrator of climatic and land use variation in Central Asia. The synthesis of broad-scale phenological changes in Central Asia showed that linkages of natural and human systems vary across space and time comprising complex and tightly integrated patterns and processes that are not evident when studied separately.

Fire patterns of South Eastern Queensland in a global context: A review

Treesearch

Philip Le C. F. Stewart; Patrick T. Moss

2015-01-01

Fire is an important driver in ecosystem evolution, composition, structure and distribution, and is vital for maintaining ecosystems of the Great Sandy Region (GSR). Charcoal records for the area dating back over 40, 000 years provide evidence of the great changes in vegetation composition, distribution and abundance in the region over time as a result of fire. Fires...

Spatial distribution of pollen grains and spores in surface sediments of Guanabara Bay, Rio de Janeiro, Brazil.

PubMed

Barreto, Cintia F; Vilela, Claudia G; Baptista-Neto, José A; Barth, Ortrud M

2012-09-01

Aiming to investigate the deposition of pollen grains and spores in Guanabara Bay, Rio de Janeiro State, 61 surface sediment samples were analyzed. The results showed that the current deposition of palynomorphs in surface sediments of Guanabara Bay represents the regional vegetation of this hydrographic basin. The differential distribution of palynomorphs followed a pattern influenced by bathymetry, tidal currents speed, discharge of numerous rivers, and by human activity. The dominance of representatives of Field Vegetation reflects the changes of the original flora caused by intense human activities in the region. The continued presence and richness of pollen types of rain forest in the samples indicates that their source area might be the vegetation from riparian border of rivers in the western sector of the Bay, where the mangrove vegetation is being preserved. The large amount of damaged palynomorphs may be related to abrasion that occurs during river transport, indicating removal or reworking from their areas of origin.

Pollen-based biomes for Beringia 18,000, 6000 and 0 14C yr BP

USGS Publications Warehouse

Edwards, M.E.; Anderson, P.M.; Brubaker, L.B.; Ager, T.A.; Andreev, A.A.; Bigelow, N.H.; Cwynar, L.C.; Eisner, Wendy R.; Harrison, S.P.; Hu, F.-S.; Jolly, D.; Lozhkin, A.V.; MacDonald, G.M.; Mock, Cary J.; Ritchie, J.C.; Sher, A.V.; Spear, R.W.; Williams, J.W.; Yu, G.

2000-01-01

The objective biomization method developed by Prentice et al. (1996) for Europe was extended using modern pollen samples from Beringia and then applied to fossil pollen data to reconstruct palaeovegetation patterns at 6000 and 18,000 14C yr BP. The predicted modern distribution of tundra, taiga and cool conifer forests in Alaska and north-western Canada generally corresponds well to actual vegetation patterns, although sites in regions characterized today by a mosaic of forest and tundra vegetation tend to be preferentially assigned to tundra. Siberian larch forests are delimited less well, probably due to the extreme under-representation of Larix in pollen spectra. The biome distribution across Beringia at 6000 14C yr BP was broadly similar to today, with little change in the northern forest limit, except for a possible northward-advance in the Mackenzie delta region. The western forest limit in Alaska was probably east of its modern position. At 18,000 14C yr BP the whole of Beringia was covered by tundra. However, the importance of the various plant functional types varied from site to site, supporting the idea that the vegetation cover was a mosaic of different tundra types.

Floristic Diversity and Distribution Pattern of Plant Communities along Altitudinal Gradient in Sangla Valley, Northwest Himalaya

PubMed Central

Rana, J. C.; Devi, Usha; Randhawa, S. S.; Kumar, Rajesh

2014-01-01

Himalayas are globally important biodiversity hotspots and are facing rapid loss in floristic diversity and changing pattern of vegetation due to various biotic and abiotic factors. This has necessitated the qualitative and quantitative assessment of vegetation here. The present study was conducted in Sangla Valley of northwest Himalaya aiming to assess the structure of vegetation and its trend in the valley along the altitudinal gradient. In the forest and alpine zones of the valley, 15 communities were recorded. Study revealed 320 species belonging to 199 genera and 75 families. Asteraceae, Rosaceae, Apiaceae, and Ranunculaceae were dominant. Among genera, Artemisia followed by Polygonum, Saussurea, Berberis, and Thalictrum were dominant. Tree and shrub's density ranged from 205 to 600 and from 105 to 1030 individual per hectare, respectively, whereas herbs ranged from 22.08 to 78.95 individual/m2. Nearly 182 species were native to the Himalaya. Maximum altitudinal distribution of few selected climate sensitive species was found to be highest in northeast and north aspects. This study gives an insight into the floristic diversity and community structure of the fragile Sangla Valley which was hitherto not available. PMID:25383363

Floodplain-wide coupling of flooding and vegetation patterns in the Tonle Sap of the Mekong River

NASA Astrophysics Data System (ADS)

Arias, M. E.; Haberstroh, C.

2017-12-01

Floodplain vegetation is one of the prime drivers of ecosystem productivity, thus floodplain-wide monitoring is critical to ensure the well-being of these ecosystems and the important services they provide to riparian societies. Therefore, the objective of this presentation is to introduce a novel methodology to monitor long-term and large-scale patterns of rooted vegetation in seasonally inundated floodplains. We applied this methodology to an floodplain area of ac. 18,000 km2 in the Tonle Sap (Cambodia), a complex hydro-ecological system directly connected to the Mekong River. The overall hypothesis of this study is that floodplain vegetation condition is dictated by gradients of disturbance from the uplands and from the flood-pulse itself. We first demonstrate that spatial vegetation patterns represented by the normalized difference vegetation index (NDVI) during the dry season -when interference from cloud cover and partial inundation is minimal- correspond well to meaningful land use/land cover groups as well as canopy cover data collected in the field. Annual trends (2000-2016) in NDVI spatial distribution showed that the modality of dry season NDVI is largely governed by the magnitude of flooding in the antecedent hydrological year. Indeed, we found a significant relationship between flood duration -defined as the number of months annually a floodplain pixel remains flooded- and floodplain-wide NDVI. We also determined that ac. 115 km2 yr-1 of the highest quality vegetation, were replaced by fallow land during the period of study. This research has important insights on the main drivers of floodplain vegetation in the Tonle Sap, and the proposed methodology, using data from freely available worldwide satellite imagery (MODIS), promises to be an effective method to monitor ecosystem change in large floodplains across the world.

Global vegetation phenology from Moderate Resolution Imaging Spectroradiometer (MODIS): Evaluation of global patterns and comparison with in situ measurements

NASA Astrophysics Data System (ADS)

Zhang, Xiaoyang; Friedl, Mark A.; Schaaf, Crystal B.

2006-12-01

In the last two decades the availability of global remote sensing data sets has provided a new means of studying global patterns and dynamics in vegetation. The vast majority of previous work in this domain has used data from the Advanced Very High Resolution Radiometer, which until recently was the primary source of global land remote sensing data. In recent years, however, a number of new remote sensing data sources have become available that have significantly improved the capability of remote sensing to monitor global ecosystem dynamics. In this paper, we describe recent results using data from NASA's Moderate Resolution Imaging Spectroradiometer to study global vegetation phenology. Using a novel new method based on fitting piecewise logistic models to time series data from MODIS, key transition dates in the annual cycle(s) of vegetation growth can be estimated in an ecologically realistic fashion. Using this method we have produced global maps of seven phenological metrics at 1-km spatial resolution for all ecosystems exhibiting identifiable annual phenologies. These metrics include the date of year for (1) the onset of greenness increase (greenup), (2) the onset of greenness maximum (maturity), (3) the onset of greenness decrease (senescence), and (4) the onset of greenness minimum (dormancy). The three remaining metrics are the growing season minimum, maximum, and summation of the enhanced vegetation index derived from MODIS. Comparison of vegetation phenology retrieved from MODIS with in situ measurements shows that these metrics provide realistic estimates of the four transition dates identified above. More generally, the spatial distribution of phenological metrics estimated from MODIS data is qualitatively realistic, and exhibits strong correspondence with temperature patterns in mid- and high-latitude climates, with rainfall seasonality in seasonally dry climates, and with cropping patterns in agricultural areas.

Evaluating simulated functional trait patterns and quantifying modelled trait diversity effects on simulated ecosystem fluxes

NASA Astrophysics Data System (ADS)

Pavlick, R.; Schimel, D.

2014-12-01

Dynamic Global Vegetation Models (DGVMs) typically employ only a small set of Plant Functional Types (PFTs) to represent the vast diversity of observed vegetation forms and functioning. There is growing evidence, however, that this abstraction may not adequately represent the observed variation in plant functional traits, which is thought to play an important role for many ecosystem functions and for ecosystem resilience to environmental change. The geographic distribution of PFTs in these models is also often based on empirical relationships between present-day climate and vegetation patterns. Projections of future climate change, however, point toward the possibility of novel regional climates, which could lead to no-analog vegetation compositions incompatible with the PFT paradigm. Here, we present results from the Jena Diversity-DGVM (JeDi-DGVM), a novel traits-based vegetation model, which simulates a large number of hypothetical plant growth strategies constrained by functional tradeoffs, thereby allowing for a more flexible temporal and spatial representation of the terrestrial biosphere. First, we compare simulated present-day geographical patterns of functional traits with empirical trait observations (in-situ and from airborne imaging spectroscopy). The observed trait patterns are then used to improve the tradeoff parameterizations of JeDi-DGVM. Finally, focusing primarily on the simulated leaf traits, we run the model with various amounts of trait diversity. We quantify the effects of these modeled biodiversity manipulations on simulated ecosystem fluxes and stocks for both present-day conditions and transient climate change scenarios. The simulation results reveal that the coarse treatment of plant functional traits by current PFT-based vegetation models may contribute substantial uncertainty regarding carbon-climate feedbacks. Further development of trait-based models and further investment in global in-situ and spectroscopic plant trait observations are needed.

Effects of Emergent Vegetation on Sediment Dynamics within a Retreating Coastal Marshland

NASA Astrophysics Data System (ADS)

Stellern, C.; Grossman, E.; Fuller, R.; Wallin, D.; Linneman, S. R.

2015-12-01

Coastal emergent vegetation in estuaries physically interrupts flow within the water column, reduces wave energy and increases sediment deposition. Previous workers conclude that wave attenuation rates decrease exponentially with distance from the marsh edge and are dependent on site and species-specific plant characteristics (Yang et al., 2011). Sediment deposition may exhibit similar patterns; however, sediment, geomorphic and habitat models seldom integrate site-specific biophysical plant parameters into change analyses. We paired vegetation and sediment dynamic studies to: (1) characterize vegetation structure, (2) estimate sediment available for deposition, (3) estimate rate, distribution and composition of sediment deposits, (4) determine sediment accumulation on vegetation, (5) compare sediment deposition within dense tidal wetland relative to non-vegetated tidal flat. These studies integrate a variety of monitoring methods, including the use of sediment traps, turbidity sensors, side-on photographs of vegetation and remote sensing image analysis. We compared sedimentation data with vegetation characteristics and spatial distribution data to examine the relative role of vegetation morphologic traits (species, stem density, biomass, distribution, tidal channels, etc.) on sediment dynamics. Our study is focused on Port Susan Bay of Washington State; a protected delta that has experienced up to 1 kilometer of marsh retreat (loss) over the past fifty years. Preliminary results show that the highest winter deposition occurred in the high marsh/mid-marsh boundary, up to 300m inland of the marsh edge, where bulrush species are most dense. These results will inform restoration efforts aimed at reestablishing sediment supply to the retreating marshland. This research is necessary to understand the vulnerability and adaptability of coastal marshlands to climate change related stressors such as, increased water levels (sea-level rise) and wave energy.

Contribution of climate and fires to vegetation composition in the boreal forest of China

NASA Astrophysics Data System (ADS)

Venevsky, S.; Wu, C.; Sitch, S.

2017-12-01

Climate is well known as an important determinant of biogeography. Although climate is directly important for vegetation composition in the boreal forests, these ecosystems are strongly sensitive to an indirect effect of climate via fire disturbance. However, the driving balance of fire disturbance and climate on composition is poorly understood. In this study we quantitatively analyzed their individual contributions for the boreal forests of the Heilongjiang province, China and their response to climate change using four warming scenarios (+1.5, 2, 3, and 4°C). This study employs the statistical methods of Redundancy Analysis (RDA) and variation partitioning combined with simulation results from a Dynamic Global Vegetation Model, SEVER-DGVM, and remote sensing datasets of global land cover (GLC2000) and the Global Fire Emissions Database (GFED3). Results show that the vegetation distribution for the present day is mainly determined directly by climate (35%) rather than fire (1%-10.9%). However, with a future global warming of 1.5°C, local vegetation composition will be determined by fires rather than climate (36.3% > 29.3%). Above a 1.5°C warming, temperature will be more important than fires in regulating vegetation distribution although other factors like precipitation can also contribute. The spatial pattern in vegetation composition over the region, as evaluated by Moran's Eigenvector Map (MEM), has a significant impact on local vegetation coverage, i.e. composition at any individual location is highly related to that in its neighborhood. It represents the largest contribution to vegetation distribution in all scenarios, but will not change the driving balance between climate and fires. Our results are highly relevant for forest and wildfires' management.

Spatial and temporal patterns of carbon storage and species richness in three South Carolina coastal plain riparian forests

Treesearch

Laura A. Giese; W. Michael Aust; Carl C. Trettin; Randall K. Kolka

2000-01-01

The distribution of organic matter within a floodplain is a controlling factor affecting water quality, habitat, and food webs. Accordingly, developn~ent of vegetation in the riparian zone can be expected to influence ecosystem functions, and organic matter storage patterns are believed to be indicators of functional recovery in disturbed riparian zones. Our objective...

Fine-Scale Habitat Heterogeneity Influences Occupancy in Terrestrial Mammals in a Temperate Region of Australia

PubMed Central

Stirnemann, Ingrid; Mortelliti, Alessio; Gibbons, Philip; Lindenmayer, David B.

2015-01-01

Vegetation heterogeneity is an inherent feature of most ecosystems, characterises the structure of habitat, and is considered an important driver of species distribution patterns. However, quantifying fine-scale heterogeneity of vegetation cover can be time consuming, and therefore it is seldom measured. Here, we determine if heterogeneity is worthwhile measuring, in addition to the amount of cover, when examining species distribution patterns. Further, we investigated the effect of the surrounding landscape heterogeneity on species occupancy. We tested the effect of cover and heterogeneity of trees and shrubs, and the context of the surrounding landscape (number of habitats and distance to an ecotone) on site occupancy of three mammal species (the black wallaby [Wallabia bicolor], the long-nosed bandicoot [Perameles nasuta], and the bush rat [Rattus fuscipes]) within a naturally heterogeneous landscape in a temperate region of Australia. We found that fine-scale heterogeneity of vegetation attributes is an important driver of mammal occurrence of two of these species. Further, we found that, although all three species responded positively to vegetation heterogeneity, different mammals vary in their response to different types of vegetation heterogeneity measurement. For example, the black wallaby responded to the proximity of an ecotone, and the bush rat and the long-nosed bandicoot responded to fine-scale heterogeneity of small tree cover, whereas none of the mammals responded to broad scale heterogeneity (i.e., the number of habitat types). Our results highlight the influence of methodological decisions, such as how heterogeneity vegetation is measured, in quantifying species responses to habitat structures. The findings confirm the importance of choosing meaningful heterogeneity measures when modelling the factors influencing occupancy of the species of interest. PMID:26394327

Socioeconomic Differences in Dietary Patterns in an East African Country: Evidence from the Republic of Seychelles.

PubMed

Mayén, Ana-Lucia; Bovet, Pascal; Marti-Soler, Helena; Viswanathan, Bharathi; Gedeon, Jude; Paccaud, Fred; Marques-Vidal, Pedro; Stringhini, Silvia

2016-01-01

In high income countries, low socioeconomic status (SES) is related to unhealthier dietary patterns, while evidence on the social patterning of diet in low and middle income countries is scarce. In this study, we assess dietary patterns in the general population of a middle income country in the African region, the Republic of Seychelles, and examine their distribution according to educational level and income. Data was drawn from two independent national surveys conducted in the Seychelles among adults aged 25-64 years in 2004 (n = 1236) and 2013 (n = 1240). Dietary patterns were assessed by principal component analysis (PCA). Educational level and income were used as SES indicators. Data from both surveys were combined as no interaction was found between SES and year. Three dietary patterns were identified: "snacks and drinks", "fruit and vegetables" and "fish and rice". No significant associations were found between SES and the "snacks and drinks" pattern. Low vs. high SES individuals had lower adherence to the "fruit and vegetables" pattern [prevalence ratio (95% CI) 0.71 (0.60-0.83)] but a higher adherence to the traditional "fish and rice" pattern [1.58 (1.32-1.88)]. Income modified the association between education and the "fish and rice" pattern (p = 0.02), whereby low income individuals had a higher adherence to this pattern in both educational groups. Low SES individuals have a lower consumption of fruit and vegetables, but a higher consumption of traditional foods like fish and rice. The Seychelles may be at a degenerative diseases stage of the nutrition transition.

A morphometric analysis of vegetation patterns in dryland ecosystems

PubMed Central

Dekker, Stefan C.; Li, Mao; Mio, Washington; Punyasena, Surangi W.; Lenton, Timothy M.

2017-01-01

Vegetation in dryland ecosystems often forms remarkable spatial patterns. These range from regular bands of vegetation alternating with bare ground, to vegetated spots and labyrinths, to regular gaps of bare ground within an otherwise continuous expanse of vegetation. It has been suggested that spotted vegetation patterns could indicate that collapse into a bare ground state is imminent, and the morphology of spatial vegetation patterns, therefore, represents a potentially valuable source of information on the proximity of regime shifts in dryland ecosystems. In this paper, we have developed quantitative methods to characterize the morphology of spatial patterns in dryland vegetation. Our approach is based on algorithmic techniques that have been used to classify pollen grains on the basis of textural patterning, and involves constructing feature vectors to quantify the shapes formed by vegetation patterns. We have analysed images of patterned vegetation produced by a computational model and a small set of satellite images from South Kordofan (South Sudan), which illustrates that our methods are applicable to both simulated and real-world data. Our approach provides a means of quantifying patterns that are frequently described using qualitative terminology, and could be used to classify vegetation patterns in large-scale satellite surveys of dryland ecosystems. PMID:28386414

A morphometric analysis of vegetation patterns in dryland ecosystems.

PubMed

Mander, Luke; Dekker, Stefan C; Li, Mao; Mio, Washington; Punyasena, Surangi W; Lenton, Timothy M

2017-02-01

Vegetation in dryland ecosystems often forms remarkable spatial patterns. These range from regular bands of vegetation alternating with bare ground, to vegetated spots and labyrinths, to regular gaps of bare ground within an otherwise continuous expanse of vegetation. It has been suggested that spotted vegetation patterns could indicate that collapse into a bare ground state is imminent, and the morphology of spatial vegetation patterns, therefore, represents a potentially valuable source of information on the proximity of regime shifts in dryland ecosystems. In this paper, we have developed quantitative methods to characterize the morphology of spatial patterns in dryland vegetation. Our approach is based on algorithmic techniques that have been used to classify pollen grains on the basis of textural patterning, and involves constructing feature vectors to quantify the shapes formed by vegetation patterns. We have analysed images of patterned vegetation produced by a computational model and a small set of satellite images from South Kordofan (South Sudan), which illustrates that our methods are applicable to both simulated and real-world data. Our approach provides a means of quantifying patterns that are frequently described using qualitative terminology, and could be used to classify vegetation patterns in large-scale satellite surveys of dryland ecosystems.

A morphometric analysis of vegetation patterns in dryland ecosystems

NASA Astrophysics Data System (ADS)

Mander, Luke; Dekker, Stefan C.; Li, Mao; Mio, Washington; Punyasena, Surangi W.; Lenton, Timothy M.

2017-02-01

Vegetation in dryland ecosystems often forms remarkable spatial patterns. These range from regular bands of vegetation alternating with bare ground, to vegetated spots and labyrinths, to regular gaps of bare ground within an otherwise continuous expanse of vegetation. It has been suggested that spotted vegetation patterns could indicate that collapse into a bare ground state is imminent, and the morphology of spatial vegetation patterns, therefore, represents a potentially valuable source of information on the proximity of regime shifts in dryland ecosystems. In this paper, we have developed quantitative methods to characterize the morphology of spatial patterns in dryland vegetation. Our approach is based on algorithmic techniques that have been used to classify pollen grains on the basis of textural patterning, and involves constructing feature vectors to quantify the shapes formed by vegetation patterns. We have analysed images of patterned vegetation produced by a computational model and a small set of satellite images from South Kordofan (South Sudan), which illustrates that our methods are applicable to both simulated and real-world data. Our approach provides a means of quantifying patterns that are frequently described using qualitative terminology, and could be used to classify vegetation patterns in large-scale satellite surveys of dryland ecosystems.

Do ecohydrology and community dynamics feed back to banded-ecosystem structure and productivity?

NASA Astrophysics Data System (ADS)

Callegaro, Chiara; Ursino, Nadia

2016-04-01

Mixed communities including grass, shrubs and trees are often reported to populate self-organized vegetation patterns. Patterns of survey data suggest that species diversity and complementarity strengthen the dynamics of banded environments. Resource scarcity and local facilitation trigger self organization, whereas coexistence of multiple species in vegetated self-organizing patches, implying competition for water and nutrients and favorable reproduction sites, is made possible by differing adaptation strategies. Mixed community spatial self-organization has so far received relatively little attention, compared with local net facilitation of isolated species. We assumed that soil moisture availability is a proxy for the environmental niche of plant species according to Ursino and Callegaro (2016). Our modelling effort was focused on niche differentiation of coexisting species within a tiger bush type ecosystem. By minimal numerical modelling and stability analysis we try to answer a few open scientific questions: Is there an adaptation strategy that increases biodiversity and ecosystem functioning? Does specific adaptation to environmental niches influence the structure of self-organizing vegetation pattern? What specific niche distribution along the environmental gradient gives the highest global productivity?

The tropical climate and vegetation response to Heinrich Event 1

NASA Astrophysics Data System (ADS)

Handiani, D. N.; Paul, A.; Prange, M.; Merkel, U.; Dupont, L. M.; Zhang, X.

2013-12-01

Past abrupt climate change associated with Heinrich Event 1 (HE1, ca. 17.5 ka BP) is thought to be connected to a slowdown of the Atlantic Meridional Overturning Circulation (AMOC). The accompanying abrupt climate changes affect not only the ocean, but also the continents. Furthermore, a strong impact on vegetation patterns during this event is registered both at high latitudes of the Northern Hemisphere and in the tropics. Pollen data from the tropical regions around the Atlantic Ocean (in our study from Angola and Brazil) suggest an effect on tropical vegetation through a southward shift of the rainbelt. However, the response appears to be very different in eastern South America and western Africa. To understand the different climate and vegetation pattern responses in the terrestrial tropics and to gain deeper insight into high-low-latitude climate interactions, we studied the climate and vegetation changes during the HE1 by using two different global climate models: the University of Victoria Earth System-Climate Model (UVic ESCM) and the Community Climate System Model version 3 (CCSM3). In both models, we simulated a similar HE1-like climate state. To facilitate the comparison between the model results and the available pollen records, we generated a distribution of biomes from the simulated plant functional type (PFT) coverage and climate parameters in the models. The UVic ESCM and the CCSM3 showed a slowdown of the AMOC accompanied by a seesaw temperature pattern between the Northern and Southern Hemispheres, as well as a southward shift of the tropical rainbelt. The response of the tropical vegetation pattern around the Atlantic Ocean was more pronounced in the CCSM3 than in the UVic ESCM simulation. In tropical South America, opposite changes in tree and grass cover were found only in CCSM3. In tropical Africa, the tree cover decreased and grass cover increased around 15°N in the UVic ESCM and around 10°N in CCSM3. Changes in tree and grass cover in tropical Southeast Asia were found only in the CCSM3 model, suggesting that the abrupt climate change during the HE1 also influenced remote tropical regions. Moreover, the biome distributions derived from both models corroborate findings from pollen records in southwestern and equatorial western Africa as well as northeastern Brazil.

Alexandrium minutum resting cyst distribution dynamics in a confined site

NASA Astrophysics Data System (ADS)

Anglès, Sílvia; Jordi, Antoni; Garcés, Esther; Basterretxea, Gotzon; Palanques, Albert

2010-02-01

The life cycle of the toxic dinoflagellate Alexandrium minutum consists of an asexual stage, characterized by motile vegetative cells, and a sexual stage, a resting cyst that once formed remains dormant in the sediment. Insight into the factors that determine the distribution and abundance of resting cysts is essential to understanding the dynamics of the vegetative phase. In investigations carried out between January 2005 and January 2008 in Arenys de Mar harbor (northwestern Mediterranean Sea), the spatial and temporal distribution patterns of A. minutum resting cysts and of the sediments were studied during different bloom stages of the vegetative population. Maximum cyst abundance was recorded mainly in the innermost part of the harbor while the lowest abundance always occurred near the harbor entrance, consistent with the distribution of silt-clay sediment fractions. The tendency of cysts in sediments to increase after bloom periods was clearly associated with new cyst formation, while cyst abundance decreased during non-bloom periods. Exceptions to this trend were observed in stations dominated by the deposition of coarse sediments. High correlation between the presence of cysts and clays during non-bloom periods indicates that cysts behave as passive sediment particles and are influenced by the same hydrodynamic processes as clays. In Arenys de Mar, the main physical forcing affecting sediment resuspension is the seiche, which was studied using in situ measurements and numerical models to interpret the observed distribution patterns. During non-bloom periods, cyst losses were smaller when the seiche was more active and at the station where the seiche-induced current was larger. Thus, seiche-forced resuspension appears to reduce cyst losses by reallocating cysts back to the sediment surface such that their burial in the sediment is avoided. The observed vertical profiles of the cysts were consistent with this process.

Paleobotany and palynology of the Bristol Hill Coal Member (Bond Formation) and Friendsville Coal Member (Mattoon Formation) of the Illinois Basin (Upper Pennsylvanian)

USGS Publications Warehouse

Willard, D.A.; Phillips, T.L.

1993-01-01

Late Pennsylvanian coal swamps of the Illinois Basin were dominated by Psarnius tree ferns with a spatially heterogeneous distribution of medullosan pteridosperms (subdominant), calamites, sigillarian lycopsids, and cordaites. Miospore and coal-ball plant assemblages from the Missourian-age Bristol Hill Coal Member (Mattoon Formation) of southeastern Illinois were quantified to analyze vegetational patterns in Late Pennsylvanian peat swamps and to compare vegetational composition of the coals. -from Authors

Diversity and above-ground biomass patterns of vascular flora induced by flooding in the drawdown area of China's Three Gorges Reservoir.

PubMed

Wang, Qiang; Yuan, Xingzhong; Willison, J H Martin; Zhang, Yuewei; Liu, Hong

2014-01-01

Hydrological alternation can dramatically influence riparian environments and shape riparian vegetation zonation. However, it was difficult to predict the status in the drawdown area of the Three Gorges Reservoir (TGR), because the hydrological regime created by the dam involves both short periods of summer flooding and long-term winter impoundment for half a year. In order to examine the effects of hydrological alternation on plant diversity and biomass in the drawdown area of TGR, twelve sites distributed along the length of the drawdown area of TGR were chosen to explore the lateral pattern of plant diversity and above-ground biomass at the ends of growing seasons in 2009 and 2010. We recorded 175 vascular plant species in 2009 and 127 in 2010, indicating that a significant loss of vascular flora in the drawdown area of TGR resulted from the new hydrological regimes. Cynodon dactylon and Cyperus rotundus had high tolerance to short periods of summer flooding and long-term winter flooding. Almost half of the remnant species were annuals. Species richness, Shannon-Wiener Index and above-ground biomass of vegetation exhibited an increasing pattern along the elevation gradient, being greater at higher elevations subjected to lower submergence stress. Plant diversity, above-ground biomass and species distribution were significantly influenced by the duration of submergence relative to elevation in both summer and previous winter. Several million tonnes of vegetation would be accumulated on the drawdown area of TGR in every summer and some adverse environmental problems may be introduced when it was submerged in winter. We conclude that vascular flora biodiversity in the drawdown area of TGR has dramatically declined after the impoundment to full capacity. The new hydrological condition, characterized by long-term winter flooding and short periods of summer flooding, determined vegetation biodiversity and above-ground biomass patterns along the elevation gradient in the drawdown area.

Diversity and Above-Ground Biomass Patterns of Vascular Flora Induced by Flooding in the Drawdown Area of China's Three Gorges Reservoir

PubMed Central

Wang, Qiang; Yuan, Xingzhong; Willison, J.H.Martin; Zhang, Yuewei; Liu, Hong

2014-01-01

Hydrological alternation can dramatically influence riparian environments and shape riparian vegetation zonation. However, it was difficult to predict the status in the drawdown area of the Three Gorges Reservoir (TGR), because the hydrological regime created by the dam involves both short periods of summer flooding and long-term winter impoundment for half a year. In order to examine the effects of hydrological alternation on plant diversity and biomass in the drawdown area of TGR, twelve sites distributed along the length of the drawdown area of TGR were chosen to explore the lateral pattern of plant diversity and above-ground biomass at the ends of growing seasons in 2009 and 2010. We recorded 175 vascular plant species in 2009 and 127 in 2010, indicating that a significant loss of vascular flora in the drawdown area of TGR resulted from the new hydrological regimes. Cynodon dactylon and Cyperus rotundus had high tolerance to short periods of summer flooding and long-term winter flooding. Almost half of the remnant species were annuals. Species richness, Shannon-Wiener Index and above-ground biomass of vegetation exhibited an increasing pattern along the elevation gradient, being greater at higher elevations subjected to lower submergence stress. Plant diversity, above-ground biomass and species distribution were significantly influenced by the duration of submergence relative to elevation in both summer and previous winter. Several million tonnes of vegetation would be accumulated on the drawdown area of TGR in every summer and some adverse environmental problems may be introduced when it was submerged in winter. We conclude that vascular flora biodiversity in the drawdown area of TGR has dramatically declined after the impoundment to full capacity. The new hydrological condition, characterized by long-term winter flooding and short periods of summer flooding, determined vegetation biodiversity and above-ground biomass patterns along the elevation gradient in the drawdown area. PMID:24971514

Vertical distribution of the soil microbiota along a successional gradient in a glacier forefield.

PubMed

Rime, Thomas; Hartmann, Martin; Brunner, Ivano; Widmer, Franco; Zeyer, Josef; Frey, Beat

2015-03-01

Spatial patterns of microbial communities have been extensively surveyed in well-developed soils, but few studies investigated the vertical distribution of micro-organisms in newly developed soils after glacier retreat. We used 454-pyrosequencing to assess whether bacterial and fungal community structures differed between stages of soil development (SSD) characterized by an increasing vegetation cover from barren (vegetation cover: 0%/age: 10 years), sparsely vegetated (13%/60 years), transient (60%/80 years) to vegetated (95%/110 years) and depths (surface, 5 and 20 cm) along the Damma glacier forefield (Switzerland). The SSD significantly influenced the bacterial and fungal communities. Based on indicator species analyses, metabolically versatile bacteria (e.g. Geobacter) and psychrophilic yeasts (e.g. Mrakia) characterized the barren soils. Vegetated soils with higher C, N and root biomass consisted of bacteria able to degrade complex organic compounds (e.g. Candidatus Solibacter), lignocellulolytic Ascomycota (e.g. Geoglossum) and ectomycorrhizal Basidiomycota (e.g. Laccaria). Soil depth only influenced bacterial and fungal communities in barren and sparsely vegetated soils. These changes were partly due to more silt and higher soil moisture in the surface. In both soil ages, the surface was characterized by OTUs affiliated to Phormidium and Sphingobacteriales. In lower depths, however, bacterial and fungal communities differed between SSD. Lower depths of sparsely vegetated soils consisted of OTUs affiliated to Acidobacteria and Geoglossum, whereas depths of barren soils were characterized by OTUs related to Gemmatimonadetes. Overall, plant establishment drives the soil microbiota along the successional gradient but does not influence the vertical distribution of microbiota in recently deglaciated soils. © 2014 John Wiley & Sons Ltd.

Native American impacts on fire regimes of the California coastal ranges

USGS Publications Warehouse

Keeley, Jon E.

2002-01-01

Aim: Native American burning impacts on California shrubland dominated landscapes are evaluated relative to the natural lightning fire potential for affecting landscape patterns. Location: Focus was on the coastal ranges of central and southern California. Methods: Potential patterns of Indian burning were evaluated based upon historical documents, ethnographic accounts, archaeological records and consideration of contemporary land management tactics. Patterns of vegetation distribution in this region were evaluated relative to environmental factors and the resilience of the dominant shrub vegetation to different fire frequencies. Results: Lightning fire frequency in this region is one of the lowest in North America and the density of pre-Columbian populations was one of the highest. Shrublands dominate the landscape throughout most of the region. These woody communities have weak resilience to high fire frequency and are readily displaced by annual grasses and forbs under high fire frequency. Intact shrublands provided limited resources for native Americans and thus there was ample motivation for using fire to degrade this vegetation to an open mosaic of shrubland/grassland, not unlike the agropastoral modification of ecologically related shrublands by Holocene peoples in the Mediterranean Basin. Alien-dominated grasslands currently cover approximately one-quarter of the landscape and less than 1% of these grasslands have a significant native grass presence. Ecological studies in the Californian coastal ranges have failed to uncover any clear soil or climate factors explaining grassland and shrubland distribution patterns. Main conclusions: Coastal ranges of California were regions of high Indian density and low frequency of lightning fires. The natural vegetation dominants on this landscape are shrubland vegetation that often form dense impenetrable stands with limited resources for Native Americans. Natural fire frequencies are not high enough to maintain these landscapes in habitable mixtures of shrublands and grasslands but such landscape mosaics are readily produced with additional human subsidy of ignitions. It is hypothesized that a substantial fraction of the landscape was type converted from shrubland to grassland and much of the landscape that underwent such type conversion has either been maintained by Euro-American land management practices or resisted recolonization of native shrublands. It appears that these patterns are disturbance dependent and result from anthropogenic alteration of landscapes initiated by Native Americans and sustained and expanded upon by Euro-American settlers.

Habitat selection by a focal predator (Canis lupus) in a multiprey ecosystem of the northern Rockies

USGS Publications Warehouse

Milakovic, B.; Parker, K.L.; Gustine, D.D.; Lay, R.J.; Walker, A.B.D.; Gillingham, M.P.

2011-01-01

Large predators respond to land cover and physiography that maximize the likelihood of encountering prey. Using locations from global positioning system-collared wolves (Canis lupus), we examined whether land cover, vegetation productivity or change, or habitat-selection value for ungulate prey species themselves most influenced patterns of selection by wolves in a large, intact multiprey system of northern British Columbia. Selection models based on land cover, in combination with topographical features, consistently outperformed models based on indexes of vegetation quantity and quality (using normalized difference vegetation index) or on selection value to prey species (moose [Alces americanus], elk [Cervus elaphus], woodland caribou [Rangifer tarandus], and Stone's sheep [Ovis dalli stonei]). Wolves generally selected for shrub communities and high diversity of cover across seasons and avoided conifer stands and non-vegetated areas and west aspects year-round. Seasonal selection strategies were not always reflected in use patterns, which showed highest frequency of use in riparian, shrub, and conifer classes. Patterns of use and selection for individual wolf packs did not always conform to global models, and appeared related to the distribution of land cover and terrain within respective home ranges. Our findings corroborate the biological linkages between wolves and their habitat related to ease of movement and potential prey associations. ?? American 2011 Society of Mammalogists.

Similarity of vegetation dynamics during interglacial periods

PubMed Central

Cheddadi, Rachid; de Beaulieu, Jacques-Louis; Jouzel, Jean; Andrieu-Ponel, Valérie; Laurent, Jeanne-Marine; Reille, Maurice; Raynaud, Dominique; Bar-Hen, Avner

2005-01-01

The Velay sequence (France) provides a unique, continuous, palynological record spanning the last four climatic cycles. A pollen-based reconstruction of temperature and precipitation displays marked climatic cycles. An analysis of the climate and vegetation changes during the interglacial periods reveals comparable features and identical major vegetation successions. Although Marine Isotope Stage (MIS) 11.3 and the Holocene had similar earth precessional variations, their correspondence in terms of vegetation dynamics is low. MIS 9.5, 7.5, and especially 5.5 display closer correlation to the Holocene than MIS 11.3. Ecological factors, such as the distribution and composition of glacial refugia or postglacial migration patterns, may explain these discrepancies. Comparison of ecosystem dynamics during the past five interglacials suggests that vegetation development in the current interglacial has no analogue from the past 500,000 years. PMID:16162676

Effects of evapotranspiration heterogeneity on catchment water balance in the Southern Sierra Nevada of California

NASA Astrophysics Data System (ADS)

Kerkez, B.; Kelly, A. E.; Lucas, R. G.; Son, K.; Glaser, S. D.; Bales, R. C.

2011-12-01

Heterogeneity of Evapotranspiration (ET) is the result of poorly understood interactions between climate, topography, vegetation and soil. Accurate predictions of ET, and thus improved water balance estimates, hinge directly upon an improved understanding of the processes that drive ET across a wide spatio-temporal range. Recent warming trends in the Western US are shifting precipitation toward more rain-dominated patterns, significantly increasing vegetation water stress in historically snow-dominated regimes due to reduced soil moisture and increased vapor deficit during warm summer months. We investigate dominant controls that govern ET variability in a highly instrumented 1km2 mountain catchment at the Southern Sierra Critical Zone Observatory, co-located in the Kings River Experimental Watershed. Various ET estimates are derived from a number of measurement approaches: an eddy flux covariance tower, ET chambers, stream flumes, groundwater monitoring wells, matric potential sensors, as well as data from a distributed wireless sensor network with over 300 sensors. Combined with precipitation data, and high-density distributed soil moisture and snowdepth readings, the ET estimates are utilized to reconstruct the overall catchment water balance. We also apply the Regional Hydro-Ecologic Simulation System (RHESSys), a physically based, spatially distributed hydrologic model, to estimate water balance components. The model predictions are compared with the water budget calculated from field data, and used to identify the key variables controlling spatial and temporal patterns of ET at multiple scales. Initial results show that ET estimates are scale-, and vegetation-dependent, with significant ET variability between vegetation types and physiographic parameters such as elevation, slope, and aspect. In mixed conifer forests terrain, ET is more dependent on soil moisture, while in the meadows, where the soil is generally saturated for the duration of the growing season, ET is driven by micro-meteorological parameters and meadow vegetation phenology.

Formation of banded vegetation patterns resulted from interactions between sediment deposition and vegetation growth.

PubMed

Huang, Tousheng; Zhang, Huayong; Dai, Liming; Cong, Xuebing; Ma, Shengnan

2018-03-01

This research investigates the formation of banded vegetation patterns on hillslopes affected by interactions between sediment deposition and vegetation growth. The following two perspectives in the formation of these patterns are taken into consideration: (a) increased sediment deposition from plant interception, and (b) reduced plant biomass caused by sediment accumulation. A spatial model is proposed to describe how the interactions between sediment deposition and vegetation growth promote self-organization of banded vegetation patterns. Based on theoretical and numerical analyses of the proposed spatial model, vegetation bands can result from a Turing instability mechanism. The banded vegetation patterns obtained in this research resemble patterns reported in the literature. Moreover, measured by sediment dynamics, the variation of hillslope landform can be described. The model predicts how treads on hillslopes evolve with the banded patterns. Thus, we provide a quantitative interpretation for coevolution of vegetation patterns and landforms under effects of sediment redistribution. Copyright © 2018. Published by Elsevier Masson SAS.

Assessment of water availability and its relationship with vegetation distribution over a tropical montane system

NASA Astrophysics Data System (ADS)

Streher, A. S.; Sobreiro, J. F. F.; Silva, T. S. F.

2017-12-01

Water availability is one of the main drivers of vegetation distribution, but assessing it over mountainous regions is difficult given the effects of rugged topography on hydroclimatic dynamics (orographic rainfall, soil water, and runoff). We assessed how water availability may influence the distribution of vegetation types in the Espinhaço Range, a South American tropical mountain landscape comprised of savannas, grasslands, rock outcrops, cloud forests, and semi-deciduous/deciduous forests. For precipitation, we used CHIRPS monthly and daily products (1981- 2016) and 112 rain gauge ground stations, and assessed potential evapotranspiration (PET) using the MODIS MOD16A3 (2000-2013) product. Vegetation types were classified according to the Global Ecoregions by WWF. We show that rainfall has well-defined rainy and dry seasons with a strong latitudinal pattern, there is evidence for local orographic effects. Dry forests (907 mm/yr; 8% cv) and caatinga vegetation (795 mm/yr; 7% cv) had the lowest average annual precipitation and low variance, whilst Atlantic tropical forest in the southeast (1267 mm/yr; 15% cv), cerrado savanna vegetation in the west (1086 mm/yr; 15% cv) and rupestrian grasslands above 800m (1261 mm/yr; 20% cv) received the highest annual precipitation, with the largest observed variance due to their wide latitudinal distribution. Forests and rupestrian grasslands in the windward side of the mountain had a higher frequency of intense rainfall events (> 20mm), accounting for 6% of the CHIRPS daily time series, suggesting orographic effects on precipitation. Annual average PET was highest for dry forests (2437 mm/yr) and caatinga (2461 mm/yr), intermediate for cerrado (2264 mm/yr) and lowest for Atlantic tropical forest (2083 mm/yr) and rupestrian grasslands (2136 mm/yr). All vegetation types received less rainfall than its PET capacity based on yearly data, emphasizing the need for ecophysiological adaptations to water use. Climate change threatens these ecosystems by possible alterations on the hydrological cycle and, consequently, capacity for adaptations on water use. These could lead to shifts in vegetation composition and distribution within the studied region. Further investigation of seasonal trends on water availability and edaphic factors would improve these analyses.

Characterization and classification of vegetation canopy structure and distribution within the Great Smoky Mountains National Park using LiDAR

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kumar, Jitendra; HargroveJr., William Walter; Norman, Steven P

Vegetation canopy structure is a critically important habit characteristic for many threatened and endangered birds and other animal species, and it is key information needed by forest and wildlife managers for monitoring and managing forest resources, conservation planning and fostering biodiversity. Advances in Light Detection and Ranging (LiDAR) technologies have enabled remote sensing-based studies of vegetation canopies by capturing three-dimensional structures, yielding information not available in two-dimensional images of the landscape pro- vided by traditional multi-spectral remote sensing platforms. However, the large volume data sets produced by airborne LiDAR instruments pose a significant computational challenge, requiring algorithms to identify andmore » analyze patterns of interest buried within LiDAR point clouds in a computationally efficient manner, utilizing state-of-art computing infrastructure. We developed and applied a computationally efficient approach to analyze a large volume of LiDAR data and to characterize and map the vegetation canopy structures for 139,859 hectares (540 sq. miles) in the Great Smoky Mountains National Park. This study helps improve our understanding of the distribution of vegetation and animal habitats in this extremely diverse ecosystem.« less

Actual evapotranspiration and deficit: Biologically meaningful correlates of vegetation distribution across spatial scales

USGS Publications Warehouse

Stephenson, N.L.

1998-01-01

Correlative approaches to understanding the climatic controls of vegetation distribution have exhibited at least two important weaknesses: they have been conceptually divorced across spatial scales, and their climatic parameters have not necessarily represented aspects of climate of broad physiological importance to plants. Using examples from the literature and from the Sierra Nevada of California, I argue that two water balance parameters-actual evapotranspiration (AET) and deficit (D)-are biologically meaningful, are well correlated with the distribution of vegetation types, and exhibit these qualities over several orders of magnitude of spatial scale (continental to local). I reach four additional conclusions. (1) Some pairs of climatic parameters presently in use are functionally similar to AET and D; however, AET and D may be easier to interpret biologically. (2) Several well-known climatic parameters are biologically less meaningful or less important than AET and D, and consequently are poorer correlates of the distribution of vegetation types. Of particular interest, AET is a much better correlate of the distributions of coniferous and deciduous forests than minimum temperature. (3) The effects of evaporative demand and water availability on a site's water balance are intrinsically different. For example, the 'dry' experienced by plants on sunward slopes (high evaporative demand) is not comparable to the 'dry' experienced by plants on soils with low water-holding capacities (low water availability), and these differences are reflected in vegetation patterns. (4) Many traditional topographic moisture scalars-those that additively combine measures related to evaporative demand and water availability are not necessarily meaningful for describing site conditions as sensed by plants; the same holds for measured soil moisture. However, using AET and D in place of moisture scalars and measured soil moisture can solve these problems.

Distribution of macroalgae and sediment chlorophyll A along salinity and elevation gradients in Oregon tidal marshes

EPA Science Inventory

Algae contribute to trophic and biogeochemical processes in tidal wetlands. We investigated patterns of sediment pigment content and macroalgal abundance and diversity in marshes in four Oregon estuaries representing a variety of vegetation types, salinity regimes, and tidal ele...

Migration Background Influences Consumption Patterns Based on Dietary Recommendations of Food Bank Users in Germany.

PubMed

Stroebele-Benschop, Nanette; Depa, Julia; Gyngell, Fiona; Müller, Annalena; Eleraky, Laila; Hilzendegen, Carolin

2018-03-29

People with low income tend to eat less balanced than people with higher income. This seems to be particularly the case for people with migration background. This cross-sectional study examined the relation of consumption patterns of 597 food bank users with different migration background in Germany. Questionnaires were distributed assessing sociodemographic information and consumption patterns. Analyses were conducted using binary logistic regressions. Models were controlled for age, gender, type of household and education. The group of German food bank users consumed fewer fruits and vegetables and less fish compared to all other groups with migration background (former USSR, Balkan region, Middle East). A significant predictor for fruit and vegetable consumption was migration status. Participants from the former USSR consumed less often SSBs compared to the other groups. Dietary recommendations for low income populations should take into consideration other aspects besides income such as migration status.

Early-warning signals for catastrophic soil degradation

NASA Astrophysics Data System (ADS)

Karssenberg, Derek

2010-05-01

Many earth systems have critical thresholds at which the system shifts abruptly from one state to another. Such critical transitions have been described, among others, for climate, vegetation, animal populations, and geomorphology. Predicting the timing of critical transitions before they are reached is of importance because of the large impact on nature and society associated with the transition. However, it is notably difficult to predict the timing of a transition. This is because the state variables of the system show little change before the threshold is reached. As a result, the precision of field observations is often too low to provide predictions of the timing of a transition. A possible solution is the use of spatio-temporal patterns in state variables as leading indicators of a transition. It is becoming clear that the critically slowing down of a system causes spatio-temporal autocorrelation and variance to increase before the transition. Thus, spatio-temporal patterns are important candidates for early-warning signals. In this research we will show that these early-warning signals also exist in geomorphological systems. We consider a modelled vegetation-soil system under a gradually increasing grazing pressure causing an abrupt shift towards extensive soil degradation. It is shown that changes in spatio-temporal patterns occur well ahead of this catastrophic transition. A distributed model describing the coupled processes of vegetation growth and geomorphological denudation is adapted. The model uses well-studied simple process representations for vegetation and geomorphology. A logistic growth model calculates vegetation cover as a function of grazing pressure and vegetation growth rate. Evolution of the soil thickness is modelled by soil creep and wash processes, as a function of net rain reaching the surface. The vegetation and soil system are coupled by 1) decreasing vegetation growth with decreasing soil thickness and 2) increasing soil wash with decreasing vegetation cover. The model describes a critical, catastrophic transition of an underexploited system with low grazing pressure towards an overexploited system. The underexploited state has high vegetation cover and well developed soils, while the overexploited state has low vegetation cover and largely degraded soils. We first show why spatio-temporal patterns in vegetation cover, morphology, erosion rate, and sediment load should be expected to change well before the critical transition towards the overexploited state. Subsequently, spatio-temporal patterns are quantified by calculating statistics, in particular first order statistics and autocorrelation in space and time. It is shown that these statistics gradually change before the transition is reached. This indicates that the statistics may serve as early-warning signals in real-world applications. We also discuss the potential use of remote sensing to predict the critical transition in real-world landscapes.

Towards an understanding of coupled physical and biological processes in the cultivated Sahel - 2. Vegetation and carbon dynamics

NASA Astrophysics Data System (ADS)

Boulain, N.; Cappelaere, B.; Ramier, D.; Issoufou, H. B. A.; Halilou, O.; Seghieri, J.; Guillemin, F.; Oï, M.; Gignoux, J.; Timouk, F.

2009-08-01

SummaryThis paper analyses the dynamics of vegetation and carbon during the West African monsoon season, for millet crop and fallow vegetation covers in the cultivated area of the Sahel. Comparing these two dominant land cover types informs on the impact of cultivation on productivity and carbon fluxes. Biomass, leaf area index (LAI) and carbon fluxes were monitored over a 2-year period for these two vegetation systems in the Wankama catchment of the AMMA (African monsoon multidisciplinary analyses) experimental super-site in West Niger. Carbon fluxes and water use efficiency observed at the field scale are confronted with ecophysiological measurements (photosynthetic response to light, and relation of water use efficiency to air humidity) made at the leaf scale for the dominant plant species in the two vegetation systems. The two rainy seasons monitored were dissimilar with respect to rain patterns, reflecting some of the interannual variability. Distinct responses in vegetation development and in carbon dynamics were observed between the two vegetation systems. Vegetation development in the fallow was found to depend more on rainfall distribution along the season than on its starting date. A quite opposite behaviour was observed for the crop vegetation: the date of first rain appears as a principal factor of millet growth. Carbon flux exchanges were well correlated to vegetation development. High responses of photosynthesis to light were observed for the dominant herbaceous and shrub species of the fallow at the leaf and field scales. Millet showed high response at the leaf scale, but a much lesser response at the field scale. This pattern, also observed for water use efficiency, is to be related to the low density of the millet cover. A simple LAI-based model for scaling up the photosynthetic response from leaf to field scale was found quite successful for the fallow, but was less conclusive for the crop, due to spatial variability of LAI. Time/space variations in leaf distribution for the dominant species are key to scale transition of carbon dynamics. Results obtained for the two vegetation covers are important in light of the major land use/cover change experienced in the Sahel region due to extensive savanna clearing for food production.

Projected future vegetation changes for the northwest United States and southwest Canada at a fine spatial resolution using a dynamic global vegetation model.

USGS Publications Warehouse

Shafer, Sarah; Bartlein, Patrick J.; Gray, Elizabeth M.; Pelltier, Richard T.

2015-01-01

Future climate change may significantly alter the distributions of many plant taxa. The effects of climate change may be particularly large in mountainous regions where climate can vary significantly with elevation. Understanding potential future vegetation changes in these regions requires methods that can resolve vegetation responses to climate change at fine spatial resolutions. We used LPJ, a dynamic global vegetation model, to assess potential future vegetation changes for a large topographically complex area of the northwest United States and southwest Canada (38.0–58.0°N latitude by 136.6–103.0°W longitude). LPJ is a process-based vegetation model that mechanistically simulates the effect of changing climate and atmospheric CO2 concentrations on vegetation. It was developed and has been mostly applied at spatial resolutions of 10-minutes or coarser. In this study, we used LPJ at a 30-second (~1-km) spatial resolution to simulate potential vegetation changes for 2070–2099. LPJ was run using downscaled future climate simulations from five coupled atmosphere-ocean general circulation models (CCSM3, CGCM3.1(T47), GISS-ER, MIROC3.2(medres), UKMO-HadCM3) produced using the A2 greenhouse gases emissions scenario. Under projected future climate and atmospheric CO2 concentrations, the simulated vegetation changes result in the contraction of alpine, shrub-steppe, and xeric shrub vegetation across the study area and the expansion of woodland and forest vegetation. Large areas of maritime cool forest and cold forest are simulated to persist under projected future conditions. The fine spatial-scale vegetation simulations resolve patterns of vegetation change that are not visible at coarser resolutions and these fine-scale patterns are particularly important for understanding potential future vegetation changes in topographically complex areas.

Projected Future Vegetation Changes for the Northwest United States and Southwest Canada at a Fine Spatial Resolution Using a Dynamic Global Vegetation Model

PubMed Central

Shafer, Sarah L.; Bartlein, Patrick J.; Gray, Elizabeth M.; Pelltier, Richard T.

2015-01-01

Future climate change may significantly alter the distributions of many plant taxa. The effects of climate change may be particularly large in mountainous regions where climate can vary significantly with elevation. Understanding potential future vegetation changes in these regions requires methods that can resolve vegetation responses to climate change at fine spatial resolutions. We used LPJ, a dynamic global vegetation model, to assess potential future vegetation changes for a large topographically complex area of the northwest United States and southwest Canada (38.0–58.0°N latitude by 136.6–103.0°W longitude). LPJ is a process-based vegetation model that mechanistically simulates the effect of changing climate and atmospheric CO2 concentrations on vegetation. It was developed and has been mostly applied at spatial resolutions of 10-minutes or coarser. In this study, we used LPJ at a 30-second (~1-km) spatial resolution to simulate potential vegetation changes for 2070–2099. LPJ was run using downscaled future climate simulations from five coupled atmosphere-ocean general circulation models (CCSM3, CGCM3.1(T47), GISS-ER, MIROC3.2(medres), UKMO-HadCM3) produced using the A2 greenhouse gases emissions scenario. Under projected future climate and atmospheric CO2 concentrations, the simulated vegetation changes result in the contraction of alpine, shrub-steppe, and xeric shrub vegetation across the study area and the expansion of woodland and forest vegetation. Large areas of maritime cool forest and cold forest are simulated to persist under projected future conditions. The fine spatial-scale vegetation simulations resolve patterns of vegetation change that are not visible at coarser resolutions and these fine-scale patterns are particularly important for understanding potential future vegetation changes in topographically complex areas. PMID:26488750

Using a spatially-distributed hydrologic biogeochemistry model with nitrogen transport to study the spatial variation of carbon stocks and fluxes in a Critical Zone Observatory

NASA Astrophysics Data System (ADS)

Shi, Y.; Eissenstat, D. M.; He, Y.; Davis, K. J.

2017-12-01

Most current biogeochemical models are 1-D and represent one point in space. Therefore, they cannot resolve topographically driven land surface heterogeneity (e.g., lateral water flow, soil moisture, soil temperature, solar radiation) or the spatial pattern of nutrient availability. A spatially distributed forest biogeochemical model with nitrogen transport, Flux-PIHM-BGC, has been developed by coupling a 1-D mechanistic biogeochemical model Biome-BGC (BBGC) with a spatially distributed land surface hydrologic model, Flux-PIHM, and adding an advection dominated nitrogen transport module. Flux-PIHM is a coupled physically based model, which incorporates a land-surface scheme into the Penn State Integrated Hydrologic Model (PIHM). The land surface scheme is adapted from the Noah land surface model, and is augmented by adding a topographic solar radiation module. Flux-PIHM is able to represent the link between groundwater and the surface energy balance, as well as land surface heterogeneities caused by topography. In the coupled Flux-PIHM-BGC model, each Flux-PIHM model grid couples a 1-D BBGC model, while nitrogen is transported among model grids via surface and subsurface water flow. In each grid, Flux-PIHM provides BBGC with soil moisture, soil temperature, and solar radiation, while BBGC provides Flux-PIHM with spatially-distributed leaf area index. The coupled Flux-PIHM-BGC model has been implemented at the Susquehanna/Shale Hills Critical Zone Observatory. The model-predicted aboveground vegetation carbon and soil carbon distributions generally agree with the macro patterns observed within the watershed. The importance of abiotic variables (including soil moisture, soil temperature, solar radiation, and soil mineral nitrogen) in predicting aboveground carbon distribution is calculated using a random forest. The result suggests that the spatial pattern of aboveground carbon is controlled by the distribution of soil mineral nitrogen. A Flux-PIHM-BGC simulation without the nitrogen transport module is also executed. The model without nitrogen transport fails in predicting the spatial patterns of vegetation carbon, which indicates the importance of having a nitrogen transport module in spatially distributed ecohydrologic modeling.

Modeling the Climate and Hydrological Controls of the Expansion of an Invasive Grass Over Southern Arizona

NASA Astrophysics Data System (ADS)

Mathias, A.; Niu, G.; Zeng, X.

2013-12-01

Climate change has an effect on the resilience of ecosystems and the occurrence of ecological perturbations (e.g. spread of invasive species, wildfires). Changes in vegetation in turn can interrupt regional scale climate patterns and alter the spatial and temporal propagation of ecological disturbances. Understanding the controls of vegetation change are essential for predicting future changes, and for setting conservation and restoration targets. Vegetation change in transition zones between ecological regions is a significant indicator of future shifts in the composition of neighboring plant communities. The Walnut Gulch Experimental Watershed is in a grassland-shrubland transition zone between the Sonoran and Chihuahuan Desert in Southern Arizona. During the past decade, at some sites the cover of the invasive Lehmann lovegrass (Eragrostis lehmanniana) drastically increased and the abundance of native vegetation decreased, causing a major decline in biodiversity. Focusing on a catchment scale (Kendall Site), we used an individual based vegetation model (ECOTONE) and a coupled vegetation-3D surface/subsurface hydrology model (ECOTONE-CATHY) to simulate vegetation change. We set up the models with soil and climatological data (NLDAS and AmeriFlux), incorporated initial conditions of species and biomass distribution and species parameters for the site. Using ECOTONE we tested our hypothesis that a combination of dry years and subsequent wet period caused Lehmann lovegass to have advantage over the natives. In ECOTONE species composition and species distribution of plant communities arise from dynamic interactions of individual plants with species specific traits through intra- and interspecific competition for resources (H2O, nitrogen) and their interaction with the environment (precipitation and temperature). Our results indicate that the competitive advantage of Lehmann lovegrass stems from its ability to withstand dryer conditions during establishment and due to its higher seed survival. We are currently using the coupled ECOTONE-CATHY models to evaluate the role of topography and hydrological processes on the patterns of invasion by Lehmann lovegrass. One hypothesis to be tested is that the redistribution of rainfall over the catchment through overland flow controls the spatial distribution of species and biomass, where wetter soil over lowland areas may buffer the effects of climatic control. All these results will be discussed in our presentation.

Using forest inventory plot data and satellite imagery from MODIS and Landsat-TM to model spatial distribution patterns of honeysuckle and privet

Treesearch

Dumitru Salajanu; Dennis M. Jacobs

2009-01-01

Forest inventory and analysis data monitor the presence and extent of certain non-native invasive species. Onforestland, non-native species are considered part of the understory vegetation and can be found near canopyopenings as well as and...

77 FR 9621 - Nez Perce-Clearwater National Forests; Idaho; Clear Creek Integrated Restoration Project

Federal Register 2010, 2011, 2012, 2013, 2014

2012-02-17

..., vegetative species distributions, habitat complexity (diversity) and landscape patterns across the forested... resistance and resilience at the landscape level; reduce fuels; improve watershed conditions; improve elk... practices and fire suppression have created a landscape that is more highly fragmented than would be...

Applied Remote Sensing Program (ARSP) to state and local government

NASA Technical Reports Server (NTRS)

Johnson, J. D.; Foster, K. E.; Mouat, D. A.; Clark, R.

1975-01-01

Environmental surveys of arid land areas (Arizona) in the United States are presented. Maps of soils, vegetation, drainage patterns, and land use are shown. The distribution of uranium deposits, oil and gas pools, is also shown. Legislation pertaining to the preservation of natural resources is discussed.

Patterns of zone management uncertainty in cotton using tarnished plant bug distributions, NDVI, soil EC, yield and thermal imagery

USDA-ARS?s Scientific Manuscript database

Management zones for various crops have been delineated using NDVI (Normalized Difference Vegetation Index), apparent bulk soil electrical conductivity (ECa - Veris), and yield data; however, estimations of uncertainty for these data layers are equally important considerations. The objective of this...

Dynamics of riparian plant communities, a new integrative ecohydrological modelling approach

NASA Astrophysics Data System (ADS)

García-Arias, Alicia; Francés, Félix

2015-04-01

The Riparian Vegetation Dynamic Model (RVDM) integrates the impacts of the hydrological extremes on the vegetation, the vegetation evolution and the competition between different vegetation classes. Considering a daily time step and a detailed spatial resolution, RVDM allows the analysis of the dynamic vegetation distribution in riverine areas during a simulated period. The riparian vegetation wellbeing and distribution are considered to be conditioned by the river hydrodynamics in RVDM. Using biomass loss functions, the stress caused by hydrological extreme events is translated into changes on the distribution of the vegetation. These extreme events are considered as removal and asphyxia associated to floods, and wilt related to droughts. The variables considered to determine the impacts are water shear stress, water table elevation and the soil moisture, respectively. RVDM includes the modelling of the natural evolution of the vegetation. The potential recruitment in bared areas, the plant growth and the succession/retrogression between plant categories are included in the model conceptualization. The recruitment takes place when seeds presence, germination and seedlings establishment overcome, so it depends on the plant reproductive period and the environmental conditions. Light use efficiency determines the vegetation growth in terms of biomass production while the soil moisture limits this biomass production and the successional evolution. Finally, the competition modelling considers the advantages between successional patterns under the specific soil moisture conditions of each unit area. Several meteorological, morphological, hydrological and hydraulic inputs are required. In addition, an initial vegetation condition is required for RVDM to start the simulation period. The model results on new vegetation maps that are considered as new inputs in the next model step. Following this approach the model simulates iteratively al the processes day by day. This model represents an improvement respect to previous models in the way of understanding the riparian dynamics. Currently, RVDM has been already implemented in a Mediterranean semi-arid river reach and a sensitivity analysis to analyze the influence of the different vegetation parameters has been performed. The good results obtained indicate that the model is suitable for scenarios analysis and for environmental flows establishment.

Modeling biomass competition and invasion in a schematic wetland

NASA Astrophysics Data System (ADS)

Ursino, N.

2010-08-01

Plants growing along hydrologic gradients adjust their biomass allocation and distribution in response to interspecific competition. Furthermore, susceptibility of a community to invasion is to some extent mediated by differences in growth habit, including root architecture and canopy hight. With reference to the study of a schematic wetland, the aim of this paper is (1) to test, via numerical modeling, the capacity of native plants to counteract an alien dominant species and cause eco-hydrological shifts of the ecosystem by changing their growth habit (e.g. allocating biomass below ground and by so doing changing the evapotranspiration locally) and (2) to test the impact on biodiversity of management practices that alter nutrient supply. The results demonstrated that unique combinations of vegetation types characterized by different growth habits may lead to different vegetation patterns under the same hydrologic forcing, and additionally, the vegetation patterns may change in response to major hydrological shifts, which could be related to diverse wetland management and restoration practices.

Groundwater controls on vegetation composition and patterning in mountain meadows

NASA Astrophysics Data System (ADS)

Lowry, Christopher S.; Loheide, Steven P., II; Moore, Courtney E.; Lundquist, Jessica D.

2011-10-01

Mountain meadows are groundwater-dependent ecosystems that are hot spots of biodiversity and productivity. In the Sierra Nevada mountains of California, these ecosystems rely on shallow groundwater to support their vegetation communities during the dry summer growing season in the region's Mediterranean montane climate. Vegetation composition in this environment is influenced by both (1) oxygen stress that occurs when portions of the root zone are saturated and anaerobic conditions limit root respiration and (2) water stress that occurs when the water table drops and the root zone becomes water limited. A spatially distributed watershed model that explicitly accounts for snowmelt processes was linked to a fine-resolution groundwater flow model of Tuolumne Meadows in Yosemite National Park, California, to simulate water table dynamics. This linked hydrologic model was calibrated to observations from a well observation network for 2006-2009. A vegetation survey was also conducted at the site in which the three dominant species were identified at more than 200 plots distributed across the meadow. Nonparametric multiplicative regression was performed to create and select the best models for predicting vegetation dominance on the basis of the simulated hydrologic regime. The hydrologic niches of three vegetation types representing wet, moist, and dry meadow vegetation communities were found to be best described using both (1) a sum exceedance value calculated as the integral of water table position above a depth threshold of oxygen stress and (2) a sum exceedance value calculated as the integral of water table position below a depth threshold of water stress. This linked hydrologic and vegetative modeling framework advances our ability to predict the propagation of human-induced climatic and land use or land cover changes through the hydrologic system to the ecosystem. The hydroecologic functioning of meadows provides an example of the extent to which cascading hydrologic processes at watershed, hillslope, and riparian zones and within channels are reflected in the composition and distribution of riparian vegetation.

Arctic Tundra Vegetation Functional Types Based on Photosynthetic Physiology and Optical Properties

NASA Technical Reports Server (NTRS)

Huemmrich, Karl F.; Gamon, John; Tweedie, Craig; Campbell, Petya P. K.; Landis, David; Middleton, Elizabeth

2012-01-01

Climate change in tundra regions may alter vegetation species composition and ecosystem carbon balance. Remote sensing provides critical tools for monitoring these changes as optical signals provide a way to scale from plot measurements to regional patterns. Gas exchange measurements of pure patches of key vegetation functional types (lichens, mosses, and vascular plants) in sedge tundra at Barrow AK, show three significantly different values of light use efficiency (LUE) with values of 0.013+/-0.001, 0.0018+/-0.0002, and 0.0012 0.0001 mol C/mol absorbed quanta for vascular plants, mosses and lichens, respectively. Further, discriminant analysis of patch reflectance identifies five spectral bands that can separate each vegetation functional type as well as nongreen material (bare soil, standing water, and dead leaves). These results were tested along a 100 m transect where midsummer spectral reflectance and vegetation coverage were measured at one meter intervals. Area-averaged canopy LUE estimated from coverage fractions of the three functional types varied widely, even over short distances. Patch-level statistical discriminant functions applied to in situ hyperspectral reflectance successfully unmixed cover fractions of the vegetation functional types. These functions, developed from the tram data, were applied to 30 m spatial resolution Earth Observing-1 Hyperion imaging spectrometer data to examine regional variability in distribution of the vegetation functional types and from those distributions, the variability of LUE. Across the landscape, there was a fivefold variation in tundra LUE that was correlated to a spectral vegetation index developed to detect vegetation chlorophyll content.

Electrical resistivity surveys to understand vegetation-water interlinkages in a northern latitude headwater catchment

NASA Astrophysics Data System (ADS)

Soulsby, C.; Dick, J.; Tetzlaff, D.; Bradford, J.

2016-12-01

The role of vegetation on the partitioning of precipitation, and the subsequent storage and release of water within the landscape is poorly understood. In particular, the relationship between vegetation and soil moisture is complex and reciprocal. The role of soil moisture as the primary source of water to plants may affect vegetation distribution. In turn, the structure of vegetation canopies may regulate water partitioning into interception, throughfall and steam flow. Such spatial differences in the inputs, together with complex patterns of water uptake from highly distributed root networks can create marked heterogeneity in soil moisture dynamics at small scales. Here, we present a study combining 3D and 2D ERT surveys with soil moisture measurements in a 3.2km upland catchment in the Scottish Highlands to understand influences of different vegetation types on spatio-temporal dynamics in soil moisture. The study focussed on one year of fortnightly ERT surveys to investigate plant-soil-water interactions within the root zone in podzolic soils. Locations were selected in both forest stands of 15m high Scots pine (Pinus sylvestris) and non-forest locations dominated by heather (Calluna vulgaris) shrubs (<0.5m high). These dominant species are typical of forest and non-forest vegetation communities in the Scottish Highlands. Results showed differences in the soil moisture dynamics under the different vegetation types, with heterogeneous patterns in the forested site mainly correlated with canopy cover and mirroring interception losses, with pronounced wetting cycles of the soil surrounding the bole of trees as a consequence of stem flow. Temporal variability in the forested site was greater, probably due to the interception, and increased evapotranspiration losses relative to the heather site, with drying typically being focussed on the areas around the trees, and reflecting the amount of water uptake. Moisture changes in the heather site were fairly heterogeneous are related to micro-topographic affects, lower interception ( 30% compared with 45%) and a smaller microclimatic effect of the canopy which serves to create greater fluctuations in soil moisture. Our results confirm the value in using geophysics to spatially elucidate subsurface plant-soil-water interactions.

Disentangling vegetation diversity from climate–energy and habitat heterogeneity for explaining animal geographic patterns

USGS Publications Warehouse

Jimenez-Alfaro, Borja; Chytry, Milan; Mucina, Ladislav; Grace, James B.; Rejmanek, Marcel

2016-01-01

Broad-scale animal diversity patterns have been traditionally explained by hypotheses focused on climate–energy and habitat heterogeneity, without considering the direct influence of vegetation structure and composition. However, integrating these factors when considering plant–animal correlates still poses a major challenge because plant communities are controlled by abiotic factors that may, at the same time, influence animal distributions. By testing whether the number and variation of plant community types in Europe explain country-level diversity in six animal groups, we propose a conceptual framework in which vegetation diversity represents a bridge between abiotic factors and animal diversity. We show that vegetation diversity explains variation in animal richness not accounted for by altitudinal range or potential evapotranspiration, being the best predictor for butterflies, beetles, and amphibians. Moreover, the dissimilarity of plant community types explains the highest proportion of variation in animal assemblages across the studied regions, an effect that outperforms the effect of climate and their shared contribution with pure spatial variation. Our results at the country level suggest that vegetation diversity, as estimated from broad-scale classifications of plant communities, may contribute to our understanding of animal richness and may be disentangled, at least to a degree, from climate–energy and abiotic habitat heterogeneity.

The interaction between vegetation and channel dynamics based on experimental findings

NASA Astrophysics Data System (ADS)

Teske, R.; Van Dijk, W. M.; Van De Lageweg, W.; Kleinhans, M. G.

2012-12-01

Strong feedbacks exist between river channel dynamics, floodplain development and riparian vegetation. Several experimental studies showed how uniformly sown vegetation causes a shift from a braided river to a single-thread and sometimes meandering river. The objective of this study is to test what the effect of fluvially distributed seeds and vegetation settling is on channel pattern change and channel dynamics. The experiments were carried out in a flume of 3 m wide and 10 m long. We tested where the vegetation deposited in a braided and meandering river and how the morphology changed. We used a simple hydrograph of 0.25 hour high flow and 3.75 hour low flow, where alfalfa seeds were added during high flow. The bed sediment consisted of a poorly sorted sediment mixture ranging from fine sand to fine gravel. The evolution was recorded by a high-resolution laser-line scanner and a Digital Single Lens Reflex (DSLR) camera used for channel floodplain segmentation, water depth approximation and vegetation distribution. In an initially braided river, vegetation settled on the higher banks and stabilized the banks. In an initially meandering river, vegetation settled in the inner scrolls, and also on the outer banks when water level exceeded bankfull conditions. In agreement with earlier work, the outer bank was stabilized; erosion rate decreased and bends became sharper. The inner bend vegetation stabilized a part of the point bar and hydraulic resistance of the vegetation steered water in the channel and to the non-vegetated part of the inner bend. As result the meander bend became braided as water flows along the vegetation. Vegetation formed patches that grew over time and reduced channel dynamics. We conclude that self-settling vegetation decreased local bank erosion and that vegetated islands leads to a multi-thread system instead of single-threaded.

Identifying high production, low production and degraded rangelands in Senegal with normalized difference vegetation index data

USGS Publications Warehouse

Tappan, G. Gray; Wood, Lynette; Moore, Donald G.

1993-01-01

Seasonal herbaceous vegetation production on Senegal's native rangelands exhibits high spatial and temporal variability. This variability can be monitored using normalized difference vegetation index (NDVI) data computed from 1-km resolution Advanced Very High Resolution Radiometer (AVHRR) image data. Although annual fluctuations in rainfall account for some of the variability, numerous long-term production patterns are evident in the AVHRR time-series data. Different n productivity reflect variations in the region's climate, topography, soils, and land use. Areas of overgrazing and intensive cultivation have caused long-term soil and vegetation degradation. Rangelands of high and low productivity, and degraded rangelands were identified using NDVI. Time-series image data from 1987 though 1992 were used to map relative rangeland productivity. The results were compared to detailed resource maps on soils, vegetation and land use. Much of the variation in rangeland productivity correlated well to the known distribution of resources. The study developed an approach that identified a number of areas of degraded soils and low vegetation production.

Spatial patterns of ecohydrologic properties on a hillslope-alluvial fan transect, central New Mexico

USGS Publications Warehouse

Bedford, D.R.; Small, E.E.

2008-01-01

Spatial patterns of soil properties are linked to patchy vegetation in arid and semi-arid landscapes. The patterns of soil properties are generally assumed to be linked to the ecohydrological functioning of patchy dryland vegetation ecosystems. We studied the effects of vegetation canopy, its spatial pattern, and landforms on soil properties affecting overland flow and infiltration in shrublands at the Sevilleta National Wildlife Refuge/LTER in central New Mexico, USA. We studied the patterns of microtopography and saturated conductivity (Ksat), and generally found it to be affected by vegetation canopy and pattern, as well as landform type. On gently sloping alluvial fans, both microtopography and Ksat are high under vegetation canopy and decay with distance from plant center. On steeper hillslope landforms, only microtopography was significantly higher under vegetation canopy, while there was no significant difference in Ksat between vegetation and interspaces. Using geostatistics, we found that the spatial pattern of soil properties was determined by the spatial pattern of vegetation. Most importantly, the effects of vegetation were present in the unvegetated interspaces 2-4 times the extent of vegetation canopy, on the order of 2-3??m. Our results have implications for the understanding the ecohydrologic function of semi-arid ecosystems as well as the parameterization of hydrologic models. ?? 2007 Elsevier B.V. All rights reserved.

Species distribution of kobs (Kobus kob) in the Shai Hills Resource Reserve: an exploratory analysis.

PubMed

Antwi, Raymond Agyepong; Owusu, Erasmus Henaku; Attuquayefio, Daniel Korley

2018-02-01

The well-being of a species fundamentally rests on understanding its biology, home range, and distribution. The highly seasonal distribution of kobs poses conservation and management difficulties, particularly because of the capricious nature of the ever-changing ecological and vegetation dynamics of the ecosystem. Assessing the distribution of kobs and their associated vegetation provides insight into the vulnerability and conservation status of the species. Species distribution and habitat suitability maps were developed and created respectively for the management of kobs in the Shai Hills Resource Reserve. Kob presence data collected was analyzed using the spatial analyst and Hawth's tool in the ArcGIS software where the gradients of kob distribution within the protected area landscape were plotted and mapped. Seven environmental variables including location, land cover/use, slope/elevation, nearness to dams and rivers, temperature, and rainfall were considered to have effect on kob distribution pattern and as such used in the development of species distribution and habitat suitability maps. The results indicated that kobs in the Shai Hills Resource Reserve (SHRR) assume a clumped or contagious distribution pattern where individual kobs are aggregated in patches. Rainfall, temperature, nearness to dams and rivers, slope/elevation, and land cover/use had influence in kob distribution. Of all the cataloged habitats, 86, 13, and 1% were moderately suitable, suitable, and unsuitable, respectively. Long-term survival of species depends on adequately large areas of suitable habitats and opportunities for home range activities between such areas. As such, it is recommended that suitable habitats for kobs be dedicated and designated as conservation areas, especially areas along the western boundary.

Plant functional types in Earth system models: past experiences and future directions for application of dynamic vegetation models in high-latitude ecosystems

PubMed Central

Wullschleger, Stan D.; Epstein, Howard E.; Box, Elgene O.; Euskirchen, Eugénie S.; Goswami, Santonu; Iversen, Colleen M.; Kattge, Jens; Norby, Richard J.; van Bodegom, Peter M.; Xu, Xiaofeng

2014-01-01

Background Earth system models describe the physical, chemical and biological processes that govern our global climate. While it is difficult to single out one component as being more important than another in these sophisticated models, terrestrial vegetation is a critical player in the biogeochemical and biophysical dynamics of the Earth system. There is much debate, however, as to how plant diversity and function should be represented in these models. Scope Plant functional types (PFTs) have been adopted by modellers to represent broad groupings of plant species that share similar characteristics (e.g. growth form) and roles (e.g. photosynthetic pathway) in ecosystem function. In this review, the PFT concept is traced from its origin in the early 1800s to its current use in regional and global dynamic vegetation models (DVMs). Special attention is given to the representation and parameterization of PFTs and to validation and benchmarking of predicted patterns of vegetation distribution in high-latitude ecosystems. These ecosystems are sensitive to changing climate and thus provide a useful test case for model-based simulations of past, current and future distribution of vegetation. Conclusions Models that incorporate the PFT concept predict many of the emerging patterns of vegetation change in tundra and boreal forests, given known processes of tree mortality, treeline migration and shrub expansion. However, representation of above- and especially below-ground traits for specific PFTs continues to be problematic. Potential solutions include developing trait databases and replacing fixed parameters for PFTs with formulations based on trait co-variance and empirical trait–environment relationships. Surprisingly, despite being important to land–atmosphere interactions of carbon, water and energy, PFTs such as moss and lichen are largely absent from DVMs. Close collaboration among those involved in modelling with the disciplines of taxonomy, biogeography, ecology and remote sensing will be required if we are to overcome these and other shortcomings. PMID:24793697

Beyond precipitation: physiographic gradients dictate the relative importance of environmental drivers on Savanna vegetation.

PubMed

Campo-Bescós, Miguel A; Muñoz-Carpena, Rafael; Kaplan, David A; Southworth, Jane; Zhu, Likai; Waylen, Peter R

2013-01-01

Understanding the drivers of large-scale vegetation change is critical to managing landscapes and key to predicting how projected climate and land use changes will affect regional vegetation patterns. This study aimed to improve our understanding of the role, magnitude and spatial distribution of the key environmental factors driving vegetation change in southern African savanna, and how they vary across physiographic gradients. We applied Dynamic Factor Analysis (DFA), a multivariate times series dimension reduction technique to ten years of monthly remote sensing data (MODIS-derived normalized difference vegetation index, NDVI) and a suite of environmental covariates: precipitation, mean and maximum temperature, soil moisture, relative humidity, fire and potential evapotranspiration. Monthly NDVI was described by cyclic seasonal variation with distinct spatiotemporal patterns in different physiographic regions. Results support existing work emphasizing the importance of precipitation, soil moisture and fire on NDVI, but also reveal overlooked effects of temperature and evapotranspiration, particularly in regions with higher mean annual precipitation. Critically, spatial distributions of the weights of environmental covariates point to a transition in the importance of precipitation and soil moisture (strongest in grass-dominated regions with precipitation<750 mm) to fire, potential evapotranspiration, and temperature (strongest in tree-dominated regions with precipitation>950 mm). We quantified the combined spatiotemporal effects of an available suite of environmental drivers on NDVI across a large and diverse savanna region. The analysis supports known drivers of savanna vegetation but also uncovers important roles of temperature and evapotranspiration. Results highlight the utility of applying the DFA approach to remote sensing products for regional analyses of landscape change in the context of global environmental change. With the dramatic increase in global change research, this methodology augurs well for further development and application of spatially explicit time series modeling to studies at the intersection of ecology and remote sensing.

Beyond Precipitation: Physiographic Gradients Dictate the Relative Importance of Environmental Drivers on Savanna Vegetation

PubMed Central

Campo-Bescós, Miguel A.; Muñoz-Carpena, Rafael; Kaplan, David A.; Southworth, Jane; Zhu, Likai; Waylen, Peter R.

2013-01-01

Background Understanding the drivers of large-scale vegetation change is critical to managing landscapes and key to predicting how projected climate and land use changes will affect regional vegetation patterns. This study aimed to improve our understanding of the role, magnitude and spatial distribution of the key environmental factors driving vegetation change in southern African savanna, and how they vary across physiographic gradients. Methodology/Principal Findings We applied Dynamic Factor Analysis (DFA), a multivariate times series dimension reduction technique to ten years of monthly remote sensing data (MODIS-derived normalized difference vegetation index, NDVI) and a suite of environmental covariates: precipitation, mean and maximum temperature, soil moisture, relative humidity, fire and potential evapotranspiration. Monthly NDVI was described by cyclic seasonal variation with distinct spatiotemporal patterns in different physiographic regions. Results support existing work emphasizing the importance of precipitation, soil moisture and fire on NDVI, but also reveal overlooked effects of temperature and evapotranspiration, particularly in regions with higher mean annual precipitation. Critically, spatial distributions of the weights of environmental covariates point to a transition in the importance of precipitation and soil moisture (strongest in grass-dominated regions with precipitation<750 mm) to fire, potential evapotranspiration, and temperature (strongest in tree-dominated regions with precipitation>950 mm). Conclusions/Significance We quantified the combined spatiotemporal effects of an available suite of environmental drivers on NDVI across a large and diverse savanna region. The analysis supports known drivers of savanna vegetation but also uncovers important roles of temperature and evapotranspiration. Results highlight the utility of applying the DFA approach to remote sensing products for regional analyses of landscape change in the context of global environmental change. With the dramatic increase in global change research, this methodology augurs well for further development and application of spatially explicit time series modeling to studies at the intersection of ecology and remote sensing. PMID:24023616

Habitat productivity constrains the distribution of social spiders across continents – case study of the genus Stegodyphus

PubMed Central

2013-01-01

Introduction Sociality has evolved independently multiple times across the spider phylogeny, and despite wide taxonomic and geographical breadth the social species are characterized by a common geographical constrain to tropical and subtropical areas. Here we investigate the environmental factors that drive macro-ecological patterns in social and solitary species in a genus that shows a Mediterranean–Afro-Oriental distribution (Stegodyphus). Both selected drivers (productivity and seasonality) may affect the abundance of potential prey insects, but seasonality may further directly affect survival due to mortality caused by extreme climatic events. Based on a comprehensive dataset including information about the distribution of three independently derived social species and 13 solitary congeners we tested the hypotheses that the distribution of social Stegodyphus species relative to solitary congeners is: (1) restricted to habitats of high vegetation productivity and (2) constrained to areas with a stable climate (low precipitation seasonality). Results Using spatial logistic regression modelling and information-theoretic model selection, we show that social species occur at higher vegetation productivity than solitary, while precipitation seasonality received limited support as a predictor of social spider occurrence. An analysis of insect biomass data across the Stegodyphus distribution range confirmed that vegetation productivity is positively correlated to potential insect prey biomass. Conclusions Habitat productivity constrains the distribution of social spiders across continents compared to their solitary congeners, with group-living in spiders being restricted to areas with relatively high vegetation productivity and insect prey biomass. As known for other taxa, permanent sociality likely evolves in response to high predation pressure and imposes within-group competition for resources. Our results suggest that group living is contingent upon productive environmental conditions where elevated prey abundance meet the increased demand for food of social groups. PMID:23433065

Infrastructure effects on estuarine wetlands increase their vulnerability to sea level rise

NASA Astrophysics Data System (ADS)

Rodriguez, Jose; Saco, Patricia; Sandi, Steven; Saintilan, Neil; Riccardi, Gerardo

2017-04-01

At the regional and global scales, coastal management and planning for future sea level rise scenarios is typically supported by modelling tools that predict the expected inundation extent. These tools rely on a number of simplifying assumptions that, in some cases, may result in important miscalculation of the inundation effects. One of such cases is estuarine wetlands, where vegetation strongly depends on both the magnitude and the timing of inundation. Many coastal wetlands display flow restrictions due to infrastructure or drainage works, which produce alterations to the inundation patterns that can not be captured by conventional models. In this contribution we explore the effects of flow restrictions on inundation patterns under sea level rise conditions in estuarine wetlands. We use a spatially-distributed dynamic wetland ecogeomorphological model that not only incorporates the effects of flow restrictions due to culverts, bridges and weirs as well as vegetation, but also considers that vegetation changes as a consequence of increasing inundation. We also consider the ability of vegetation to capture sediment and produce accretion. We apply our model to an estuarine wetland in Australia and show that our model predicts a much faster wetland loss due to sea level rise than conventional approaches.

The soil carbon/nitrogen ratio and moisture affect microbial community structures in alkaline permafrost-affected soils with different vegetation types on the Tibetan plateau.

PubMed

Zhang, Xinfang; Xu, Shijian; Li, Changming; Zhao, Lin; Feng, Huyuan; Yue, Guangyang; Ren, Zhengwei; Cheng, Guogdong

2014-01-01

In the Tibetan permafrost region, vegetation types and soil properties have been affected by permafrost degradation, but little is known about the corresponding patterns of their soil microbial communities. Thus, we analyzed the effects of vegetation types and their covariant soil properties on bacterial and fungal community structure and membership and bacterial community-level physiological patterns. Pyrosequencing and Biolog EcoPlates were used to analyze 19 permafrost-affected soil samples from four principal vegetation types: swamp meadow (SM), meadow (M), steppe (S) and desert steppe (DS). Proteobacteria, Acidobacteria, Bacteroidetes and Actinobacteria dominated bacterial communities and the main fungal phyla were Ascomycota, Basidiomycota and Mucoromycotina. The ratios of Proteobacteria/Acidobacteria decreased in the order: SM>M>S>DS, whereas the Ascomycota/Basidiomycota ratios increased. The distributions of carbon and nitrogen cycling bacterial genera detected were related to soil properties. The bacterial communities in SM/M soils degraded amines/amino acids very rapidly, while polymers were degraded rapidly by S/DS communities. UniFrac analysis of bacterial communities detected differences among vegetation types. The fungal UniFrac community patterns of SM differed from the others. Redundancy analysis showed that the carbon/nitrogen ratio had the main effect on bacteria community structures and their diversity in alkaline soil, whereas soil moisture was mainly responsible for structuring fungal communities. Thus, microbial communities and their functioning are probably affected by soil environmental change in response to permafrost degradation. Copyright © 2014 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

Investigation of residual fluoroquinolones in a soil-vegetable system in an intensive vegetable cultivation area in Northern China.

PubMed

Li, Xue-Wen; Xie, Yun-Feng; Li, Cang-Lin; Zhao, Hui-Nan; Zhao, Hui; Wang, Ning; Wang, Jin-Feng

2014-01-15

One of the largest vegetable cultivation field sites in Northeast China was selected to investigate the occurrence and distribution pattern of fluoroquinolones (FQs) in the soil-vegetable system. A total of 100 surface soil samples and 68 vegetable samples were collected from this study area. The antibiotic concentration was analyzed using high-performance liquid chromatography tandem mass spectrometry. Results indicated the presence of FQs in all soil samples. Ciprofloxacin (CIP) had the highest mean concentration, at 104.4 μg · kg(-1) in the soil, a level that represents a relatively high risk to the environment and to human health. However, in the vegetable samples, norfloxacin (NOR) was significantly higher than CIP and enrofloxacin (ENR), ranging from 18.2 to 658.3 μg · kg(-1). The transfer ability of NOR in soil-vegetables is greater than that of CIP and ENR. Moreover, we found that the solanaceous fruits had a higher antibiotic accumulation ability than the leafy vegetables. Taken together, these data indicate that greater attention should be paid to the region in which vegetables with higher accumulation ability are grown. © 2013.

Ecohydrological interactions within "fairy circles" in the Namib Desert: Revisiting the self-organization hypothesis

NASA Astrophysics Data System (ADS)

Ravi, Sujith; Wang, Lixin; Kaseke, Kudzai Farai; Buynevich, Ilya V.; Marais, Eugene

2017-02-01

Vegetation patterns such as rings, bands, and spots are recurrent characteristics of resource-limited arid and semiarid ecosystems. One of the most recognizable vegetation patterns is the millions of circular patches, often referred to as "fairy circles," within the arid grassland matrix extending over hundreds of kilometers in the Namib Desert. Several modeling studies have highlighted the role of plant-soil interactions in the formation of these fairy circles. However, little is known about the spatial and temporal variabilities of hydrological processes inside a fairy circle. In particular, a detailed field assessment of hydrological and soil properties inside and outside the fairy circles is limited. We conducted extensive measurements of infiltration rate, soil moisture, grass biometric, and sediment grain-size distribution from multiple circles and interspaces in the Namib Desert. Our results indicate that considerable heterogeneity in hydrological processes exists within the fairy circles, resulting from the presence of coarser particles in the inner bare soil areas, whereas concentration of fine soil occurs on the vegetated edges. The trapping of aeolian and water-borne sediments by plants may result in the observed soil textural changes beneath the vegetation, which in turn, explains the heterogeneity in hydrological processes such as infiltration and runoff. Our investigation provides new insights and experimental data on the ecohydrological processes associated with fairy circles, from a less studied location devoid of sand termite activity within the circles. The results seem to provide support to the "self-organization hypothesis" of fairy circle formation attributed to the antiphase spatial biomass-water distributions.

[Spatio-temporal analysis of the biophysical and ecological conditions of Triatoma dimidiata (Hemiptera: Reduviidae: Triatominae) in the northeast region of Colombia].

PubMed

Badel-Mogollón, Jaime; Rodríguez-Figueroa, Laura; Parra-Henao, Gabriel

2017-03-29

Due to the lack of information regarding biophysical and spatio-temporal conditions (hydrometheorologic and vegetal coverage density) in areas with Triatoma dimidiata in the Colombian departments of Santander and Boyacá, there is a need to elucidate the association patterns of these variables to determine the distribution and control of this species. To make a spatio-temporal analysis of biophysical variables related to the distribution of T. dimidiate observed in the northeast region of Colombia. We used the Intergovernmental Panel on Climate Change Special Report on Emissions Scenarios (IPCC SRES) data bases registering vector presence and hydrometheorologic data. We studied the variables of environmental temperature, relative humidity, rainfall and vegetal coverage density at regional and local levels, and we conducted spatial geostatistic, descriptive statistical and Fourier temporal series analyses. Temperatures two meters above the ground and on covered surface ranged from 14,5°C to 18,8°C in the areas with the higher density of T. dimidiata. The environmental temperature fluctuated between 30 and 32°C. Vegetal coverage density and rainfall showed patterns of annual and biannual peaks. Relative humidity values fluctuated from 66,8 to 85,1%. Surface temperature and soil coverage were the variables that better explained the life cycle of T. dimidiata in the area. High relative humidity promoted the seek of shelters and an increase of the geographic distribution in the annual and biannual peaks of regional rainfall. The ecologic and anthropic conditions suggest that T. dimidiata is a highly resilient species.

Previous land use alters plant allocation and growth in forest herbs

Treesearch

Jennifer M. Fraterrigo; Monica G. Turner; Scott M. Pearson

2006-01-01

Former human practices can persistently influence forest ecosystems, particularly by altering the distribution and abundance of vegetation. Previous research has focused on the role of colonization success in governing plant community patterns in abandoned forests, but few studies have explored how changes in the performance of adult plants may contribute to...

Bioversity in Multi-Ownership Landscapes

Treesearch

Thomas A. Spies; K. Norman Johnson

2005-01-01

Many landscapes in the West are a patchwork of federal, state, forest industry and nonindustrial private forestlands. Each of these owners has a particular set of goals and practices that shapes the structure, species and dynamics of forest vegetation on their lands. Consequently, the pattern of landownership can have a major effect on the distribution of plants and...

Terrestrial gross carbon dioxide uptake: global distribution and covariation with climate.

PubMed

Beer, Christian; Reichstein, Markus; Tomelleri, Enrico; Ciais, Philippe; Jung, Martin; Carvalhais, Nuno; Rödenbeck, Christian; Arain, M Altaf; Baldocchi, Dennis; Bonan, Gordon B; Bondeau, Alberte; Cescatti, Alessandro; Lasslop, Gitta; Lindroth, Anders; Lomas, Mark; Luyssaert, Sebastiaan; Margolis, Hank; Oleson, Keith W; Roupsard, Olivier; Veenendaal, Elmar; Viovy, Nicolas; Williams, Christopher; Woodward, F Ian; Papale, Dario

2010-08-13

Terrestrial gross primary production (GPP) is the largest global CO(2) flux driving several ecosystem functions. We provide an observation-based estimate of this flux at 123 +/- 8 petagrams of carbon per year (Pg C year(-1)) using eddy covariance flux data and various diagnostic models. Tropical forests and savannahs account for 60%. GPP over 40% of the vegetated land is associated with precipitation. State-of-the-art process-oriented biosphere models used for climate predictions exhibit a large between-model variation of GPP's latitudinal patterns and show higher spatial correlations between GPP and precipitation, suggesting the existence of missing processes or feedback mechanisms which attenuate the vegetation response to climate. Our estimates of spatially distributed GPP and its covariation with climate can help improve coupled climate-carbon cycle process models.

Modelling of Space-Time Soil Moisture in Savannas and its Relation to Vegetation Patterns

NASA Astrophysics Data System (ADS)

Rodriguez-Iturbe, I.; Mohanty, B.; Chen, Z.

2017-12-01

A physically derived space-time representation of the soil moisture field is presented. It includes the incorporation of a "jitter" process acting over the space-time soil moisture field and accounting for the short distance heterogeneities in topography, soil, and vegetation characteristics. The modelling scheme allows for the representation of spatial random fluctuations of soil moisture at small spatial scales and reproduces quite well the space-time correlation structure of soil moisture from a field study in Oklahoma. It is shown that the islands of soil moisture above different thresholds have sizes which follow power distributions over an extended range of scales. A discussion is provided about the possible links of this feature with the observed power law distributions of the clusters of trees in savannas.

Declines in moose population density at Isle Royle National Park, MI, USA and accompanied changes in landscape patterns

USGS Publications Warehouse

De Jager, N. R.; Pastor, J.

2009-01-01

Ungulate herbivores create patterns of forage availability, plant species composition, and soil fertility as they range across large landscapes and consume large quantities of plant material. Over time, herbivore populations fluctuate, producing great potential for spatio-temporal landscape dynamics. In this study, we extend the spatial and temporal extent of a long-term investigation of the relationship of landscape patterns to moose foraging behavior at Isle Royale National Park, MI. We examined how patterns of browse availability and consumption, plant basal area, and soil fertility changed during a recent decline in the moose population. We used geostatistics to examine changes in the nature of spatial patterns in two valleys over 18 years and across short-range and long-range distance scales. Landscape patterns of available and consumed browse changed from either repeated patches or randomly distributed patches in 1988-1992 to random point distributions by 2007 after a recent record high peak followed by a rapid decline in the moose population. Patterns of available and consumed browse became decoupled during the moose population low, which is in contrast to coupled patterns during the earlier high moose population. Distributions of plant basal area and soil nitrogen availability also switched from repeated patches to randomly distributed patches in one valley and to random point distributions in the other valley. Rapid declines in moose population density may release vegetation and soil fertility from browsing pressure and in turn create random landscape patterns. ?? Springer Science+Business Media B.V. 2009.

How much does the time lag between wildlife field-data collection and LiDAR-data acquisition matter for studies of animal distributions? A case study using bird communities

Treesearch

Kerri T. Vierling; Charles E. Swift; Andrew T. Hudak; Jody C. Vogeler; Lee A. Vierling

2014-01-01

Vegetation structure quantified by light detection and ranging (LiDAR) can improve understanding of wildlife occupancy and species-richness patterns. However, there is often a time lag between the collection of LiDAR data and wildlife data. We investigated whether a time lag between the LiDAR acquisition and field-data acquisition affected mapped wildlife distributions...

The Upper Mississippi River floodscape: spatial patterns of flood inundation and associated plant community distributions

USGS Publications Warehouse

DeJager, Nathan R.; Rohweder, Jason J.; Yin, Yao; Hoy, Erin E.

2016-01-01

Questions How is the distribution of different plant communities associated with patterns of flood inundation across a large floodplain landscape? Location Thirty-eight thousand nine hundred and seventy hectare of floodplain, spanning 320 km of the Upper Mississippi River (UMR). Methods High-resolution elevation data (Lidar) and 30 yr of daily river stage data were integrated to produce a ‘floodscape’ map of growing season flood inundation duration. The distributions of 16 different remotely sensed plant communities were quantified along the gradient of flood duration. Results Models fitted to the cumulative frequency of occurrence of different vegetation types as a function of flood duration showed that most types exist along a continuum of flood-related occurrence. The diversity of community types was greatest at high elevations (0–10 d of flooding), where both upland and lowland community types were found, as well as at very low elevations (70–180 d of flooding), where a variety of lowland herbaceous communities were found. Intermediate elevations (20–60 d of flooding) tended to be dominated by floodplain forest and had the lowest diversity of community types. Conclusions Although variation in flood inundation is often considered to be the main driver of spatial patterns in floodplain plant communities, few studies have quantified flood–vegetation relationships at broad scales. Our results can be used to identify targets for restoration of historical hydrological regimes or better anticipate hydro-ecological effects of climate change at broad scales.

Spatiotemporal pattern of vegetation remote sensing phenology and its response to climatic factors on the Qinghai-Tibet Plateau

NASA Astrophysics Data System (ADS)

An, S.; Chen, X.

2015-12-01

Based on the MODIS MCD12Q2 remote sensing phenology product, we analyzed spatiotemporal variations of vegetation green-up, maturity, senescence and brown-off dates, and their relation to spatiotemporal patterns of air temperature and precipitation on the Qinghai-Tibet Plateau (QTP). From 2001 to 2012, phenological time series at about 11.7%~15.1% pixels indicate significant linear trends (P<0.1) with strong spatial consistency. Namely, pixels with significant phenological advancement and growing season lengthening are mainly distributed in the middle and eastern parts of the QTP, while pixels with significant phenological delay and growing season shortening are mainly distributed in the western and southern parts as well as the eastern edge of the QTP. Similar spatial patterns for positive and negative linear trends of the minimum and maximum EVI, and the time-integrated EVI during the growing season were detected in the above two regions, respectively. With regard to climatic factors, mean annual temperature shows an increased trend over the QTP except for the eastern edge, whereas annual precipitation displays an increased trend in the middle and eastern parts but a decreased trend in the western and southern parts as well as the eastern edge of the QTP. These findings suggest that phenological advancement, growing season lengthening, and vegetation activity enhancement in the middle and eastern parts might be attributed to coincident temperature and precipitation increase. By contrast, phenological delay, growing season shortening, and vegetation activity reduction in the western and southern parts as well as the eastern edge might be caused by opposite changes of temperature and precipitation, and strong evaporation induced water shortage. Furthermore, a partial correlation analysis indicates that green-up, maturity, and brown-off dates were influenced by preceding temperature and precipitation, while senescence date was affected by preceding precipitation.

Colorado River Vegetation, and Climate: Five Decades of Spatio-Temporal Dynamics in the Grand Canyon in Response to River Regulation

NASA Astrophysics Data System (ADS)

Ralston, B. E.; Sankey, J. B.

2013-12-01

Recent analysis of remotely sensed imagery of 400 km of the Colorado River confirms a net increase in vegetated area has occurred since the completion of Glen Canyon Dam in 1963. The rates and magnitude of vegetation change appear to be river stage-dependent. Riparian vegetation expansion on geomorphic surfaces at lower elevations relative to the river was greater for decades with lower peak and average discharges. Vegetation change at higher elevation relative to the river indicate that increases and decreases in vegetated area reflect regional precipitation patterns, and respectively coincide with regionally significant wet and dry periods that include the current early 21st century drought. The objective of this work was to examine the temporal persistence, and changes, in the spatial distribution of riparian vegetation relative to geomorphic characteristics of the Colorado River in Grand Canyon, dam and reservoir management, and regional climate over the 5-decade period from the mid-1960s to present. We employed archived riparian vegetation classifications that used aerial imagery from 1965, 1973, 1984, 1992, 2002, and 2009 coupled with flow regime data that is primarily related to operations of Glen Canyon Dam, field-measured rating relations, predictions of rating relations based on 1-D modeling, and detailed, geomorphic field mapping. Documentation of the effects of river regulation on riparian habitats in the SW USA has traditionally been limited to either small segments of river channels (e.g., 0.1-10km), or focused on specific plant species. The smaller geographic scale approach evaluates local hydrology, river channel changes, and serial recruitment events of riparian plants. The species-specific plant response informs larger scale patterns of riparian plant distributions across the landscape, but is less sensitive to differences of climate and hydrology among rivers. Our study is unique in that it employs datasets that allow both large-scale change detection and local-scale analysis to address questions about transferability of local-scale plant response to the larger river system. Furthermore, we assess the independent and interacting effects of river regulation and regional climate on plant response. Our results show promise for improved understanding of the interplay of river regulation and climate effects for riparian vegetation at a local and river-wide scale in this highly modified river system.

Spatial Self-Organization of Vegetation Subject to Climatic Stress-Insights from a System Dynamics-Individual-Based Hybrid Model.

PubMed

Vincenot, Christian E; Carteni, Fabrizio; Mazzoleni, Stefano; Rietkerk, Max; Giannino, Francesco

2016-01-01

In simulation models of populations or communities, individual plants have often been obfuscated in favor of aggregated vegetation. This simplification comes with a loss of biological detail and a smoothing out of the demographic noise engendered by stochastic individual-scale processes and heterogeneities, which is significant among others when studying the viability of small populations facing challenging fluctuating environmental conditions. This consideration has motivated the development of precise plant-centered models. The accuracy gained in the representation of plant biology has then, however, often been balanced by the disappearance in models of important plant-soil interactions (esp. water dynamics) due to the inability of most individual-based frameworks to simulate complex continuous processes. In this study, we used a hybrid modeling approach, namely integrated System Dynamics (SD)-Individual-based (IB), to illustrate the importance of individual plant dynamics to explain spatial self-organization of vegetation in arid environments. We analyzed the behavior of this model under different parameter sets either related to individual plant properties (such as seed dispersal distance and reproductive age) or the environment (such as intensity and yearly distribution of precipitation events). While the results of this work confirmed the prevailing theory on vegetation patterning, they also revealed the importance therein of plant-level processes that cannot be rendered by reaction-diffusion models. Initial spatial distribution of plants, reproductive age, and average seed dispersal distance, by impacting patch size and vegetation aggregation, affected pattern formation and population survival under climatic variations. Besides, changes in precipitation regime altered the demographic structure and spatial organization of vegetation patches by affecting plants differentially depending on their age and biomass. Water availability influenced non-linearly total biomass density. Remarkably, lower precipitation resulted in lower mean plant age yet higher mean individual biomass. Moreover, seasonal variations in rainfall greater than a threshold (here, ±0.45 mm from the 1.3 mm baseline) decreased mean total biomass and generated limit cycles, which, in the case of large variations, were preceded by chaotic demographic and spatial behavior. In some cases, peculiar spatial patterns (e.g., rings) were also engendered. On a technical note, the shortcomings of the present model and the benefit of hybrid modeling for virtual investigations in plant science are discussed.

Spatial Self-Organization of Vegetation Subject to Climatic Stress—Insights from a System Dynamics—Individual-Based Hybrid Model

PubMed Central

Vincenot, Christian E.; Carteni, Fabrizio; Mazzoleni, Stefano; Rietkerk, Max; Giannino, Francesco

2016-01-01

In simulation models of populations or communities, individual plants have often been obfuscated in favor of aggregated vegetation. This simplification comes with a loss of biological detail and a smoothing out of the demographic noise engendered by stochastic individual-scale processes and heterogeneities, which is significant among others when studying the viability of small populations facing challenging fluctuating environmental conditions. This consideration has motivated the development of precise plant-centered models. The accuracy gained in the representation of plant biology has then, however, often been balanced by the disappearance in models of important plant-soil interactions (esp. water dynamics) due to the inability of most individual-based frameworks to simulate complex continuous processes. In this study, we used a hybrid modeling approach, namely integrated System Dynamics (SD)—Individual-based (IB), to illustrate the importance of individual plant dynamics to explain spatial self-organization of vegetation in arid environments. We analyzed the behavior of this model under different parameter sets either related to individual plant properties (such as seed dispersal distance and reproductive age) or the environment (such as intensity and yearly distribution of precipitation events). While the results of this work confirmed the prevailing theory on vegetation patterning, they also revealed the importance therein of plant-level processes that cannot be rendered by reaction-diffusion models. Initial spatial distribution of plants, reproductive age, and average seed dispersal distance, by impacting patch size and vegetation aggregation, affected pattern formation and population survival under climatic variations. Besides, changes in precipitation regime altered the demographic structure and spatial organization of vegetation patches by affecting plants differentially depending on their age and biomass. Water availability influenced non-linearly total biomass density. Remarkably, lower precipitation resulted in lower mean plant age yet higher mean individual biomass. Moreover, seasonal variations in rainfall greater than a threshold (here, ±0.45 mm from the 1.3 mm baseline) decreased mean total biomass and generated limit cycles, which, in the case of large variations, were preceded by chaotic demographic and spatial behavior. In some cases, peculiar spatial patterns (e.g., rings) were also engendered. On a technical note, the shortcomings of the present model and the benefit of hybrid modeling for virtual investigations in plant science are discussed. PMID:27252707

Spatial hydrological flow processes, water quality, sediment and vegetation community distributions in a natural floodplain fen - implication for the Flood Pulse Concept

NASA Astrophysics Data System (ADS)

Keizer, Floris; Schot, Paul; Wassen, Martin; Kardel, Ignacy; Okruszko, Tomasz

2017-04-01

We studied spatial patterns in inundation water quality, sediment and vegetation distribution in a floodplain fen in Poland to map interacting peatland hydrological processes. Using PCA and K-means cluster analysis, we identified four water types, related to river water inundation, discharge of clean and polluted groundwater, and precipitation and snowmelt dilution. Spatially, these hydrochemical water types are related to known water sources in the floodplain and occupy distinctive zones. River water is found along the river, clean and polluted groundwater at the valley margins and groundwater diluted with precipitation and snowmelt water in the central part of the floodplain. This implies that, despite the floodplain being completely inundated, nutrient input from river flooding occurs only in a relatively narrow zone next to the river. Our findings question the relevance of the edge of inundation, as presented in the Flood Pulse Concept, as delineating the zone of input and turnover of nutrients. Secondly, we studied rich-fen and freshwater vegetation community distributions in relation to the presented inundation water quality types. We successfully determined inundation water quality preference for 14 out of 17 studied rich-fen and freshwater communities in the floodplain. Spatial patterns in preference show vegetation with attributed river water preference to occur close to the river channel, with increasing distance to the river followed by communities with no preference, diluted groundwater preference in the central part, and clean and polluted groundwater preference at the valley margins. In inundation water, nutrients are known to be transported mainly as attached to sediment, besides in dissolved state. This means that in the zone where sediment deposition occurs, nutrient input can be a relevant contribution to the nutrient input of the floodplain. We found a significant decrease in sediment-attached nutrient deposition with distance from the river. Sediment-attached nutrients correlated better to aboveground standing biomass than dissolved nutrients. These findings further reduce the spatial zone where significant nutrient input is influenced by transport from the river, compared to the zone influenced by dissolved nutrients. Our findings indicate the need for a revision of the Flood Pulse Concept for temperate river with multiple water sources, as peatland hydrological processes significantly influence spatial floodplain vegetation distribution.

Vegetation Patterns and Degradation Thresholds in the Mulga Landscapes of Australia

NASA Astrophysics Data System (ADS)

Azadi, Samira; Saco, Patricia; Moreno-de las Heras, Mariano; Willgoose, Garry

2017-04-01

Drylands are often characterised by a spatially heterogeneous vegetation cover forming mosaics of patches dense vegetation within bare soil. This 'patterned' or 'patchy' vegetation cover is sensitive to human pressures. Previous work suggests that within these landscapes there is a critical vegetation cover threshold below which the landscape functionality is lost. This threshold behaviour is tightly linked to the overland flow redistribution and an increase in hydrologic connectivity that induces loss of resources (i.e., leakiness). In fact, disturbances (such as wildfire, overgrazing or harvesting activities) can disrupt the spatial structure of vegetation, increase landscape hydrologic connectivity, trigger erosion and produce a substantial loss of water. All these effects affect ecosystem functionality. Here we present the results of exploring the impact of degradation processes induced by vegetation disturbances (mainly grazing) on ecosystem functionality and connectivity in semiarid landscapes with various types of vegetation patterns. The sites are carefully selected in Mulga landscapes bioregion (New South Wales, Queensland) and in sites of Northern Territory in Australia, which display similar vegetation characteristics but with different vegetation patterns and good quality rainfall information. The analysis of vegetation patterns is derived from high resolution remote sensing images (IKONOS, QuickBird, Pleiades). Using MODIS NDVI and local precipitation data, we compute rainfall use efficiency and precipitation marginal response in order to assess the ecosystem functionality. We use vegetation binary maps and digital elevation models to estimate mean Flowlength as an indicator of structural hydrologic connectivity. We compare the trends for several sites with varying vegetation patterns (i.e., banded versus spotted patterns). Our results show that disturbances increase hydrologic connectivity and suggest threshold behaviour that affects landscape functionality. Though this threshold behaviour is found in all sites, the plots in higher rainfall landscapes with banded vegetation patterns show evidence of higher resilience. We will also present some preliminary modelling results that complement this analysis and capture the coevolution of vegetation and landforms (erosion), leading to this type of threshold behaviour.

Patterns of reflected radiance associated with geobotanical anomalies

NASA Technical Reports Server (NTRS)

Birnie, R. W.; Stone, T. A.; Francica, J. R.

1985-01-01

This paper summarizes three remote sensing experiments in which changes in remotely measured reflected radiance patterns of vegetation correlated with changes in geology. In two cases using airborne spectroradiometer data, changes in the physical properties of a uniform species correlated with zones of porphyry copper mineralization. In another case using Landsat digital data, changes were detected in the distribution and density of a number of species and combined with soil brightness data to produce a composite index useful for distinguishing lithologies.

Relationships of Biomass with Environmental Factors in the Grassland Area of Hulunbuir, China

PubMed Central

Liu, Miao; Liu, Guohua; Gong, Li; Wang, Dongbo; Sun, Jian

2014-01-01

Many studies have focused on the relationship between vegetation biomass and environmental factors in grassland. However, several questions remain to be answered, especially with regards to the spatial pattern of vegetation biomass. Thus, the distributed mechanism will be explored in the present study. Here, plant biomass was measured at 23 sites along a transect survey during the peak growing season in 2006. The data were analyzed with a classification and regression tree (CART) model. The structural equation modeling (SEM) was conducted to explicitly evaluate the both direct and indirect effects of these critical environmental elements on vegetation biomass. The results demonstrated that mean annual temperature (MAT) affected aboveground biomass (AGB) scored at −0.811 (P<0.05). The direct effect of MAT on belowground biomass (BGB) was −0.490 (P<0.05). The results were determined by SEM. Our results indicate that AGB and BGB in semi-arid ecosystems is strongly affected by precipitation and temperature. Future work shall attempt to take into account the integrated effects of precipitation and temperature. Meanwhile, partitioning the influences of environmental variations and vegetation types are helpful in illuminating the internal mechanism of biomass distribution. PMID:25032808

Relationships of biomass with environmental factors in the grassland area of Hulunbuir, China.

PubMed

Liu, Miao; Liu, Guohua; Gong, Li; Wang, Dongbo; Sun, Jian

2014-01-01

Many studies have focused on the relationship between vegetation biomass and environmental factors in grassland. However, several questions remain to be answered, especially with regards to the spatial pattern of vegetation biomass. Thus, the distributed mechanism will be explored in the present study. Here, plant biomass was measured at 23 sites along a transect survey during the peak growing season in 2006. The data were analyzed with a classification and regression tree (CART) model. The structural equation modeling (SEM) was conducted to explicitly evaluate the both direct and indirect effects of these critical environmental elements on vegetation biomass. The results demonstrated that mean annual temperature (MAT) affected aboveground biomass (AGB) scored at -0.811 (P<0.05). The direct effect of MAT on belowground biomass (BGB) was -0.490 (P<0.05). The results were determined by SEM. Our results indicate that AGB and BGB in semi-arid ecosystems is strongly affected by precipitation and temperature. Future work shall attempt to take into account the integrated effects of precipitation and temperature. Meanwhile, partitioning the influences of environmental variations and vegetation types are helpful in illuminating the internal mechanism of biomass distribution.

Evaluation of DGVMs in tropical areas: linking patterns of vegetation cover, climate and fire to ecological processes

NASA Astrophysics Data System (ADS)

D'Onofrio, Donatella; von Hardenberg, Jost; Baudena, Mara

2017-04-01

Many current Dynamic Global Vegetation Models (DGVMs), including those incorporated into Earth System Models (ESMs), are able to realistically reproduce the distribution of the most worldwide biomes. However, they display high uncertainty in predicting the forest, savanna and grassland distributions and the transitions between them in tropical areas. These biomes are the most productive terrestrial ecosystems, and owing to their different biogeophysical and biogeochemical characteristics, future changes in their distributions could have also impacts on climate states. In particular, expected increasing temperature and CO2, modified precipitation regimes, as well as increasing land-use intensity could have large impacts on global biogeochemical cycles and precipitation, affecting the land-climate interactions. The difficulty of the DGVMs in simulating tropical vegetation, especially savanna structure and occurrence, has been associated with the way they represent the ecological processes and feedbacks between biotic and abiotic conditions. The inclusion of appropriate ecological mechanisms under present climatic conditions is essential for obtaining reliable future projections of vegetation and climate states. In this work we analyse observed relationships of tree and grass cover with climate and fire, and the current ecological understanding of the mechanisms driving the forest-savanna-grassland transition in Africa to evaluate the outcomes of a current state-of-the-art DGVM and to assess which ecological processes need to be included or improved within the model. Specifically, we analyse patterns of woody and herbaceous cover and fire return times from MODIS satellite observations, rainfall annual average and seasonality from TRMM satellite measurements and tree phenology information from the ESA global land cover map, comparing them with the outcomes of the LPJ-GUESS DGVM, also used by the EC-Earth global climate model. The comparison analysis with the LPJ-GUESS simulations suggests possible improvements in the model representations of tree-grass competition for water and in the vegetation-fire interaction. The proposed method could be useful for evaluating DGVMs in tropical areas, especially in the phase of model setting-up, before the coupling with Earth System Models. This could help in improving the simulations of ecological processes and consequently of land-climate interactions.

Hydrological Validation of The Lpj Dynamic Global Vegetation Model - First Results and Required Actions

NASA Astrophysics Data System (ADS)

Haberlandt, U.; Gerten, D.; Schaphoff, S.; Lucht, W.

Dynamic global vegetation models are developed with the main purpose to describe the spatio-temporal dynamics of vegetation at the global scale. Increasing concern about climate change impacts has put the focus of recent applications on the sim- ulation of the global carbon cycle. Water is a prime driver of biogeochemical and biophysical processes, thus an appropriate representation of the water cycle is crucial for their proper simulation. However, these models usually lack thorough validation of the water balance they produce. Here we present a hydrological validation of the current version of the LPJ (Lund- Potsdam-Jena) model, a dynamic global vegetation model operating at daily time steps. Long-term simulated runoff and evapotranspiration are compared to literature values, results from three global hydrological models, and discharge observations from various macroscale river basins. It was found that the seasonal and spatial patterns of the LPJ-simulated average values correspond well both with the measurements and the results from the stand-alone hy- drological models. However, a general underestimation of runoff occurs, which may be attributable to the low input dynamics of precipitation (equal distribution within a month), to the simulated vegetation pattern (potential vegetation without anthro- pogenic influence), and to some generalizations of the hydrological components in LPJ. Future research will focus on a better representation of the temporal variability of climate forcing, improved description of hydrological processes, and on the consider- ation of anthropogenic land use.

Patterns of megafloral change across the Cretaceous-Tertiary boundary in the Northern Great Plains and Rocky Mountains

NASA Technical Reports Server (NTRS)

Johnson, Kirk R.; Hickey, Leo J.

1988-01-01

The spatial and temporal distribution of vegetation in the terminal Cretaceous of Western Interior North America was a complex mosaic resulting from the interaction of factors including a shifting coastline, tectonic activity, a mild, possibly deteriorating climate, dinosaur herbivory, local facies effects, and a hypothesized bolide impact. In order to achieve sufficient resolution to analyze this vegetational pattern, over 100 megafloral collecting sites were established, yielding approximately 15,000 specimens, in Upper Cretaceous and lower Paleocene strata in the Williston, Powder River, and Bighorn basins in North Dakota, Montana, and Wyoming. These localities were integrated into a lithostratigraphic framework that is based on detailed local reference sections and constrained by vertebrate and palynomorph biostratigraphy, magnetostratigraphy, and sedimentary facies analysis. A regional biostratigraphy based on well located and identified plant megafossils that can be used to address patterns of floral evolution, ecology, and extinction is the goal of this research. Results of the analyses are discussed.

Spatial and Temporal Variation in Primary Productivity (NDVI) of Coastal Alaskan Tundra: Decreased Vegetation Growth Following Earlier Snowmelt

NASA Technical Reports Server (NTRS)

Gamon, John A.; Huemmrich, K. Fred; Stone, Robert S.; Tweedie, Craig E.

2015-01-01

In the Arctic, earlier snowmelt and longer growing seasons due to warming have been hypothesized to increase vegetation productivity. Using the Normalized Difference Vegetation Index (NDVI) from both field and satellite measurements as an indicator of vegetation phenology and productivity, we monitored spatial and temporal patterns of vegetation growth for a coastal wet sedge tundra site near Barrow, Alaska over three growing seasons (2000-2002). Contrary to expectation, earlier snowmelt did not lead to increased productivity. Instead, productivity was associated primarily with precipitation and soil moisture, and secondarily with growing degree days, which, during this period, led to reduced growth in years with earlier snowmelt. Additional moisture effects on productivity and species distribution, operating over a longer time scale, were evident in spatial NDVI patterns associated with microtopography. Lower, wetter regions dominated by graminoids were more productive than higher, drier locations having a higher percentage of lichens and mosses, despite the earlier snowmelt at the more elevated sites. These results call into question the oft-stated hypothesis that earlier arctic growing seasons will lead to greater vegetation productivity. Rather, they agree with an emerging body of evidence from recent field studies indicating that early-season, local environmental conditions, notably moisture and temperature, are primary factors determining arctic vegetation productivity. For this coastal arctic site, early growing season conditions are strongly influenced by microtopography, hydrology, and regional sea ice dynamics, and may not be easily predicted from snowmelt date or seasonal average air temperatures alone. Our comparison of field to satellite NDVI also highlights the value of in-situ monitoring of actual vegetation responses using field optical sampling to obtain detailed information on surface conditions not possible from satellite observations alone.

Effects of riparian vegetation on topographic change during a large flood event, Rio Puerco, New Mexico, USA

USGS Publications Warehouse

Perignon, M. C.; Tucker, G.E.; Griffin, Eleanor R.; Friedman, Jonathan M.

2013-01-01

The spatial distribution of riparian vegetation can strongly influence the geomorphic evolution of dryland rivers during large floods. We present the results of an airborne lidar differencing study that quantifies the topographic change that occurred along a 12 km reach of the Lower Rio Puerco, New Mexico, during an extreme event in 2006. Extensive erosion of the channel banks took place immediately upstream of the study area, where tamarisk and sandbar willow had been removed. Within the densely vegetated study reach, we measure a net volumetric change of 578,050 ± ∼ 490,000 m3, with 88.3% of the total aggradation occurring along the floodplain and channel and 76.7% of the erosion focusing on the vertical valley walls. The sediment derived from the devegetated reach deposited within the first 3.6 km of the study area, with depth decaying exponentially with distance downstream. Elsewhere, floodplain sediments were primarily sourced from the erosion of valley walls. Superimposed on this pattern are the effects of vegetation and valley morphology on sediment transport. Sediment thickness is seen to be uniform among sandbar willows and highly variable within tamarisk groves. These reach-scale patterns of sedimentation observed in the lidar differencing likely reflect complex interactions of vegetation, flow, and sediment at the scale of patches to individual plants.

Using Behavioral Risk Factor Surveillance System data to estimate the percent of the population meeting USDA Food Patterns fruit and vegetable intake recommendations

PubMed Central

Moore, Latetia V; Dodd, Kevin W; Thompson, Frances E; Grimm, Kirsten A; Kim, Sonia A; Scanlon, Kelley S

2015-01-01

Most Americans do not eat enough fruits and vegetables with significant variation by state. State-level self-reported frequency of fruit and vegetable consumption is available from the Centers for Disease Control and Prevention’s Behavioral Risk Factor Surveillance System (BRFSS). However, BRFSS cannot be used to directly compare states’ progress towards national goals because of incongruence in units used to measure intake and because distributions from frequency data are not reflective of usual intake. To help states track progress, we developed scoring algorithms from external data and applied them to 2011 BRFSS data to estimate the percent of each state’s adult population meeting United States Department of Agriculture Food Patterns fruit and vegetable intake recommendations. We used 24 hour dietary recall data from the 2007–2010 National Health and Nutrition Examination Survey to fit sex- and age-specific models that estimate probabilities of meeting recommendations as functions of reported consumption frequency, race/ethnicity, and poverty-income ratio adjusting for intra-individual variation. Regression parameters derived from these models were applied to BRFSS to estimate percent meeting recommendations. We estimate that 7–18% of state populations met fruit recommendations and 5–12% met vegetable recommendations. Our method provides a new tool for states to track progress towards meeting dietary recommendations. PMID:25935424

An Ecology of Prestige in New York City: Examining the Relationships Among Population Density, Socio-economic Status, Group Identity, and Residential Canopy Cover

NASA Astrophysics Data System (ADS)

Grove, J. Morgan; Locke, Dexter H.; O'Neil-Dunne, Jarlath P. M.

2014-09-01

Several social theories have been proposed to explain the uneven distribution of vegetation in urban residential areas: population density, social stratification, luxury effect, and ecology of prestige. We evaluate these theories using a combination of demographic and socio-economic predictors of vegetative cover on all residential lands in New York City. We use diverse data sources including the City's property database, time-series demographic and socio-economic data from the US Census, and land cover data from the University of Vermont's Spatial Analysis Lab (SAL). These data are analyzed using a multi-model inferential, spatial econometrics approach. We also examine the distribution of vegetation within distinct market categories using Claritas' Potential Rating Index for Zipcode Markets (PRIZM™) database. These categories can be disaggregated, corresponding to the four social theories. We compare the econometric and categorical results for validation. Models associated with ecology of prestige theory are more effective for predicting the distribution of vegetation. This suggests that private, residential patterns of vegetation, reflecting the consumption of environmentally relevant goods and services, are associated with different lifestyles and lifestages. Further, our spatial and temporal analyses suggest that there are significant spatial and temporal dependencies that have theoretical and methodological implications for understanding urban ecological systems. These findings may have policy implications. Decision makers may need to consider how to most effectively reach different social groups in terms of messages and messengers in order to advance land management practices and achieve urban sustainability.

An ecology of prestige in New York City: examining the relationships among population density, socio-economic status, group identity, and residential canopy cover.

PubMed

Grove, J Morgan; Locke, Dexter H; O'Neil-Dunne, Jarlath P M

2014-09-01

Several social theories have been proposed to explain the uneven distribution of vegetation in urban residential areas: population density, social stratification, luxury effect, and ecology of prestige. We evaluate these theories using a combination of demographic and socio-economic predictors of vegetative cover on all residential lands in New York City. We use diverse data sources including the City's property database, time-series demographic and socio-economic data from the US Census, and land cover data from the University of Vermont's Spatial Analysis Lab (SAL). These data are analyzed using a multi-model inferential, spatial econometrics approach. We also examine the distribution of vegetation within distinct market categories using Claritas' Potential Rating Index for Zipcode Markets (PRIZM™) database. These categories can be disaggregated, corresponding to the four social theories. We compare the econometric and categorical results for validation. Models associated with ecology of prestige theory are more effective for predicting the distribution of vegetation. This suggests that private, residential patterns of vegetation, reflecting the consumption of environmentally relevant goods and services, are associated with different lifestyles and lifestages. Further, our spatial and temporal analyses suggest that there are significant spatial and temporal dependencies that have theoretical and methodological implications for understanding urban ecological systems. These findings may have policy implications. Decision makers may need to consider how to most effectively reach different social groups in terms of messages and messengers in order to advance land management practices and achieve urban sustainability.

Geographical ecology of the palms (Arecaceae): determinants of diversity and distributions across spatial scales

PubMed Central

Eiserhardt, Wolf L.; Svenning, Jens-Christian; Kissling, W. Daniel; Balslev, Henrik

2011-01-01

Background The palm family occurs in all tropical and sub-tropical regions of the world. Palms are of high ecological and economical importance, and display complex spatial patterns of species distributions and diversity. Scope This review summarizes empirical evidence for factors that determine palm species distributions, community composition and species richness such as the abiotic environment (climate, soil chemistry, hydrology and topography), the biotic environment (vegetation structure and species interactions) and dispersal. The importance of contemporary vs. historical impacts of these factors and the scale at which they function is discussed. Finally a hierarchical scale framework is developed to guide predictor selection for future studies. Conclusions Determinants of palm distributions, composition and richness vary with spatial scale. For species distributions, climate appears to be important at landscape and broader scales, soil, topography and vegetation at landscape and local scales, hydrology at local scales, and dispersal at all scales. For community composition, soil appears important at regional and finer scales, hydrology, topography and vegetation at landscape and local scales, and dispersal again at all scales. For species richness, climate and dispersal appear to be important at continental to global scales, soil at landscape and broader scales, and topography at landscape and finer scales. Some scale–predictor combinations have not been studied or deserve further attention, e.g. climate on regional to finer scales, and hydrology and topography on landscape and broader scales. The importance of biotic interactions – apart from general vegetation structure effects – for the geographic ecology of palms is generally underexplored. Future studies should target scale–predictor combinations and geographic domains not studied yet. To avoid biased inference, one should ideally include at least all predictors previously found important at the spatial scale of investigation. PMID:21712297

[Correlative analysis of the diversity patterns of regional surface water, NDVI and thermal environment].

PubMed

Duan, Jin-Long; Zhang, Xue-Lei

2012-10-01

Taking Zhengzhou City, the capital of Henan Province in Central China, as the study area, and by using the theories and methodologies of diversity, a discreteness evaluation on the regional surface water, normalized difference vegetation index (NDVI), and land surface temperature (LST) distribution was conducted in a 2 km x 2 km grid scale. Both the NDVI and the LST were divided into 4 levels, their spatial distribution diversity indices were calculated, and their connections were explored. The results showed that it was of operability and practical significance to use the theories and methodologies of diversity in the discreteness evaluation of the spatial distribution of regional thermal environment. There was a higher overlap of location between the distributions of surface water and the lowest temperature region, and the high vegetation coverage was often accompanied by low land surface temperature. In 1988-2009, the discreteness of the surface water distribution in the City had an obvious decreasing trend. The discreteness of the surface water distribution had a close correlation with the discreteness of the temperature region distribution, while the discreteness of the NDVI classification distribution had a more complicated correlation with the discreteness of the temperature region distribution. Therefore, more environmental factors were needed to be included for a better evaluation.

Validation of solar radiation surfaces from MODIS and reanalysis data over topographically complex terrain

Treesearch

Todd A. Schroeder; Robbie Hember; Nicholas C. Coops; Shunlin Liang

2009-01-01

The magnitude and distribution of incoming shortwave solar radiation (SW) has significant influence on the productive capacity of forest vegetation. Models that estimate forest productivity require accurate and spatially explicit radiation surfaces that resolve both long- and short-term temporal climatic patterns and that account for topographic variability of the land...

Vegetation-environment relations of the Chisos Mountains, Big Bend National Park, Texas

Treesearch

Helen M. Poulos; Ann E. Camp

2005-01-01

The Sky Island Archipelagos of the Sierra Madre Oriental and Occidental contain a unique array of endemic flora and fauna. Plant species composition in these elevationally restricted forests is thought to vary in relation to environmental gradients. This study quantifies plant population abundance and spatial distribution patterns in pine-oak woodlands of Big Bend...

Modeling effects of climate change and fire management on western white pine (Pinus monticola) in the northern Rocky Mountains, USA

Treesearch

Rachel A. Loehman; Jason A. Clark; Robert E. Keane

2011-01-01

Climate change is projected to profoundly influence vegetation patterns and community compositions, either directly through increased species mortality and shifts in species distributions or indirectly through disturbance dynamics such as increased wildfire activity and extent, shifting fire regimes, and pathogenesis. Mountainous landscapes have been shown to be...

Riparian soil seed banks and the potential for passive restoration of giant reed infested areas in Webb County, Texas

USDA-ARS?s Scientific Manuscript database

Habitat restoration projects can use seed bank information as early warning systems of patterns or degrees of habitat degradation; as changes in above ground vegetation directly impact below ground seed distribution. In multiple strategy restoration efforts, seed bank quality can be used as a decidi...

The role of elevation, relative sea-level history and vegetation transition in determining carbon distribution in Spartina alterniflora dominated salt marshes

NASA Astrophysics Data System (ADS)

Kulawardhana, Ranjani W.; Feagin, Rusty A.; Popescu, Sorin C.; Boutton, Thomas W.; Yeager, Kevin M.; Bianchi, Thomas S.

2015-03-01

Spartina alterniflora salt marshes are among the most productive ecosystems on earth, and represent a substantial global carbon sink. Understanding the spatial heterogeneity in the distribution of both above- and below-ground carbon in these wetland ecosystems is especially important considering their potential in carbon sequestration projects, as well as for conservation efforts in the context of a changing climate and rising sea-level. Through the use of extensive field sampling and remote sensing data (Light Detection and Ranging - LiDAR, and aerial images), we sought to map and explain how vegetation biomass and soil carbon are related to elevation and relative sea-level change in a S. alterniflora dominated salt marsh on Galveston Island, Texas. The specific objectives of this study were to: 1) understand the relationship between elevation and the distribution of salt marsh vegetation percent cover, plant height, plant density, above-and below-ground biomass, and carbon, and 2) evaluate the temporal changes in relative sea-level history, vegetation transitions, and resulting changes in the patterns of soil carbon distribution. Our results indicated a clear zonation of terrain and vegetation characteristics (i.e., height, cover and biomass). In the soil profile, carbon concentrations and bulk densities showed significant and abrupt change at a depth of ∼10-15 cm. This apparent transition in the soil characteristics coincided temporally with a transformation of the land cover, as driven by a rapid increase in relative sea-level around this time at the sample locations. The amounts of soil carbon stored in recently established S. alterniflora intertidal marshes were significantly lower than those that have remained in situ for a longer period of time. Thus, in order to quantify and predict carbon in coastal wetlands, and also to understand the heterogeneity in the spatial distribution of carbon stocks, it is essential to understand not only the elevation, the relative sea-level rise rate, and the vertical accretion rate - but also the history of land cover change and vegetation transition.

Tundra landform and vegetation productivity trend maps for the Arctic Coastal Plain of northern Alaska

NASA Astrophysics Data System (ADS)

Lara, Mark J.; Nitze, Ingmar; Grosse, Guido; McGuire, A. David

2018-04-01

Arctic tundra landscapes are composed of a complex mosaic of patterned ground features, varying in soil moisture, vegetation composition, and surface hydrology over small spatial scales (10-100 m). The importance of microtopography and associated geomorphic landforms in influencing ecosystem structure and function is well founded, however, spatial data products describing local to regional scale distribution of patterned ground or polygonal tundra geomorphology are largely unavailable. Thus, our understanding of local impacts on regional scale processes (e.g., carbon dynamics) may be limited. We produced two key spatiotemporal datasets spanning the Arctic Coastal Plain of northern Alaska (~60,000 km2) to evaluate climate-geomorphological controls on arctic tundra productivity change, using (1) a novel 30 m classification of polygonal tundra geomorphology and (2) decadal-trends in surface greenness using the Landsat archive (1999-2014). These datasets can be easily integrated and adapted in an array of local to regional applications such as (1) upscaling plot-level measurements (e.g., carbon/energy fluxes), (2) mapping of soils, vegetation, or permafrost, and/or (3) initializing ecosystem biogeochemistry, hydrology, and/or habitat modeling.

Tundra landform and vegetation productivity trend maps for the Arctic Coastal Plain of northern Alaska.

PubMed

Lara, Mark J; Nitze, Ingmar; Grosse, Guido; McGuire, A David

2018-04-10

Arctic tundra landscapes are composed of a complex mosaic of patterned ground features, varying in soil moisture, vegetation composition, and surface hydrology over small spatial scales (10-100 m). The importance of microtopography and associated geomorphic landforms in influencing ecosystem structure and function is well founded, however, spatial data products describing local to regional scale distribution of patterned ground or polygonal tundra geomorphology are largely unavailable. Thus, our understanding of local impacts on regional scale processes (e.g., carbon dynamics) may be limited. We produced two key spatiotemporal datasets spanning the Arctic Coastal Plain of northern Alaska (~60,000 km 2 ) to evaluate climate-geomorphological controls on arctic tundra productivity change, using (1) a novel 30 m classification of polygonal tundra geomorphology and (2) decadal-trends in surface greenness using the Landsat archive (1999-2014). These datasets can be easily integrated and adapted in an array of local to regional applications such as (1) upscaling plot-level measurements (e.g., carbon/energy fluxes), (2) mapping of soils, vegetation, or permafrost, and/or (3) initializing ecosystem biogeochemistry, hydrology, and/or habitat modeling.

Surface pollen and its relationship to vegetation in the Zoige Basin, eastern Tibetan Plateau

NASA Astrophysics Data System (ADS)

Li, Furong; Zhao, Yan; Sun, Jinghui; Zhao, Wenwei; Guo, Xiaoli; Zhang, Ke

2011-09-01

We use a data set of 23 surface pollen samples from moss polsters in the Zoige Basin to explore the relationship between modern pollen assemblages and contemporary vegetation patterns. The surface pollen samples spanned four types of plant communities: Carex muliensis marsh, Stipa and Kobresia meadow, Carex-dominated forb meadow and Sibiraea angustata scrub. Principal-components analysis (PCA) was used to determine the relationships between modern pollen and vegetation and environmental variables. The results show that the pollen assemblages of surface moss samples generally reflect the features of the modern vegetation, basically similar in the vegetation types and the dominant genera; however, they don't show a very clear distinction between different communities. Our results also demonstrate that pollen representation of different families or genus varied. Some tree taxa, such as Pinus and Betula, and herb types, such as Artemisia are over-represented, while Asteraceae, Ranunculaceae and Cyperaceae are moderately represented, and Poaceae and Rosaceae are usually under-represented in our study region. PCA results indicate that the distribution of vegetation in the Zoige Basin is mainly controlled by precipitation and altitude.

Transgenes sustain epigeal insect biodiversity in diversified vegetable farm systems.

PubMed

Leslie, T W; Hoheisel, G A; Biddinger, D J; Rohr, J R; Fleischer, S J

2007-02-01

Many ecological studies have focused on the effects of transgenes in field crops, but few have considered multiple transgenes in diversified vegetable systems. We compared the epigeal, or soil surface-dwelling, communities of Coleoptera and Formicidae between transgenic and isoline vegetable systems consisting of sweet corn, potato, and acorn squash, with transgenic cultivars expressing Cry1(A)b, Cry3, or viral coat proteins. Vegetables were grown in replicated split plots over 2 yr with integrated pest management (IPM) standards defining insecticide use patterns. More than 77.6% of 11,925 insects from 1,512 pitfall traps were identified to species, and activity density was used to compare dominance distribution, species richness, and community composition. Measures of epigeal biodiversity were always equal in transgenic vegetables, which required fewer insecticide applications than their near isolines. There were no differences in species richness between transgenic and isoline treatments at the farm system and individual crop level. Dominance distributions were also similar between transgenic and isoline farming systems. Crop type, and not genotype, had a significant influence on Carabidae and Staphylinidae community composition in the first year, but there were no treatment effects in the second year, possibly because of homogenizing effects of crop rotations. Communities were more influenced by crop type, and possibly crop rotation, than by genotype. The heterogeneity of crops and rotations in diversified vegetable farms seems to aid in preserving epigeal biodiversity, which may be supplemented by reductions in insecticide use associated with transgenic cultivars.

Geographic patterns of ground-dwelling arthropods across an ecoregional transition in the north American Southwest

USGS Publications Warehouse

Lightfoot, D.C.; Brantley, S.L.; Allen, Craig D.

2008-01-01

We examined the biogeographic patterns of ground-dwelling arthropod communities across a heterogeneous semiarid region of the Southern Rio Grande Rift Valley of New Mexico. Our 3 sites included portions of 5 ecoregions, with the middle site a transition area where all ecoregions converged. We addressed the following 3 questions: (1) Do the species assemblage patterns for ground arthropods across habitats and sites conform to recognized ecoregions? (2) Are arthropod assemblages in distinct vegetation-defined habitats within an ecoregion more similar to each other or to assemblages in similar vegetation-defined habitats in other ecoregions? (3) Is there a detectable edge effect with increased arthropod diversity in the area of converging ecoregions? We encountered 442 target arthropod species from pitfall traps operating continuously for 7 years over a series of different habitats at each of the 3 sites. We examined geographic distributions of spider and cricket/grasshopper species in detail, and they showed affinities for different ecoregions, respectively. Each habitat within a study site supported a unique overall arthropod assemblage; nevertheless, different habitats at the same site were more similar to each other than they were to similar habitats at other sites. Overall arthropod species richness was greatest in the area where all 5 ecoregions converged. Arthropod species and their geographic distributions are poorly known relative to vascular plants and vertebrate animals. Findings from this research indicate that ecoregional classification is a useful tool for understanding biogeographic patterns among arthropods.

Groundwater Controls on Vegetation Composition and Patterning in Mountain Meadows

NASA Astrophysics Data System (ADS)

Loheide, S. P.; Lowry, C.; Moore, C. E.; Lundquist, J. D.

2010-12-01

Mountain meadows are groundwater dependent ecosystems that are hotspots of biodiversity and productivity in the Sierra Nevada of California. Meadow vegetation relies on shallow groundwater during the region’s dry summer growing season. Vegetation composition in this environment is influenced both by 1) oxygen stress that occurs when portions of the root zone are saturated and anaerobic conditions are created that limit root respiration and 2) water stress that occurs when the water table drops and water-limited conditions are created in the root zone. A watershed model that explicitly accounts for snowmelt processes was linked to a fine resolution groundwater flow model of Tuolumne Meadows in Yosemite National Park, CA to simulated spatially distributed water table dynamics. This linked hydrologic model was calibrated to observations from a well observation network for 2006-2008, and validated using data from 2009. A vegetation survey was also conducted at the site in which the three dominant species were identified at more than 200 plots distributed across the meadow. Nonparametric multiplicative regression was performed to create and select the best models for predicting vegetation dominance based on simulated hydrologic regime. The hydrologic niche of three vegetation types representing wet, moist, and dry meadow vegetation communities was best described using both 1) a sum exceedance value calculated as the integral of water table position above a threshold of oxygen stress and 2) a sum deceedance value calculated as the integral of water table position below a threshold of water stress. This linked hydrologic and vegetative modeling framework advances our ability to predict the propagation of human-induced climatic and land-use/-cover changes through the hydrologic system to the ecosystem.

The copper spoil heap Knappenberg, Austria, as a model for metal habitats - Vegetation, substrate and contamination.

PubMed

Adlassnig, Wolfram; Weiss, Yasmin S; Sassmann, Stefan; Steinhauser, Georg; Hofhansl, Florian; Baumann, Nils; Lichtscheidl, Irene K; Lang, Ingeborg

2016-09-01

Historic mining in the Eastern Alps has left us with a legacy of numerous spoil heaps hosting specific, metal tolerant vegetation. Such habitats are characterized by elevated concentrations of toxic elements but also by high irradiation, a poorly developed substrate or extreme pH of the soil. This study investigates the distribution of vascular plants, mosses and lichens on a copper spoil heap on the ore bearing Knappenberg formed by Prebichl Layers and Werfener Schist in Lower Austria. It serves as a model for discriminating between various ecological traits and their effects on vegetation. Five distinct clusters were distinguished: (1) The bare, metal rich Central Spoil Heap was only colonised by highly resistant specialists. (2) The Northern and (3) Southern Peripheries contained less copper; the contrasting vegetation was best explained by the different microclimate. (4) A forest over acidic bedrock hosted a vegetation overlapping with the periphery of the spoil heap. (5) A forest over calcareous bedrock was similar to the spoil heap with regard to pH and humus content but hosted a vegetation differing strongly to all other habitats. Among the multiple toxic elements at the spoil heap, only Cu seems to exert a crucial influence on the vegetation pattern. Besides metal concentrations, irradiation, humidity, humus, pH and grain size distribution are important for the establishment of a metal tolerant vegetation. The difference between the species poor Northern and the diverse Southern Periphery can be explained by the microclimate rather than by the substrate. All plant species penetrating from the forest into the periphery of the spoil heap originate from the acidic but not from the calcareous bedrock. Copyright © 2016 Elsevier B.V. All rights reserved.

Assessing the impact of future land use and land cover changes on climate over Brazilian semiarid

NASA Astrophysics Data System (ADS)

Cunha, A. M.; Alvalá, R. S.; Kubota, P. Y.; Vieira, R.

2013-12-01

The continental surface vegetal cover has been considerably changed by human activities, mainly through natural vegetation conversion in grasslands. Such changes in surface cover may impact the regional and global climates, through of the changes in biophysical processes and CO2 exchanges between vegetation and atmosphere. In recent decades, most of the Brazilian territory has been presenting transformation in the land use/cover spatial patterns. The typical vegetation of the Brazilian semiarid, known as caatinga (closed shrubland) had been replaced by pasture lands. Based on that, the main objective of this work was to investigate the impacts of future land cover and land use changes (LCLUC) on surface processes and on the climate of Brazilian semiarid region. Numerical experiments using the AGCM/CPTEC/IBIS were performed in order to investigate the impacts of LCLUC on the climate of Brazilian semiarid due to the replacement of natural vegetation by pasture and degraded areas. The climate impacts of LUCC were assessed using climate simulations considering two scenarios of vegetation distribution: i) Potential Vegetation (Control) and ii) Future scenario of the vegetation: maximum pasture limited by areas of desert and semidesert. These degraded areas were obtained from the future projection of the biome distribution in South America developed by Salazar Velasquez (2009) using CPTEC PVMReg and emission scenarios A2 of the Intergovernmental Panel on Climate Change (IPCC). In general, the simulation results showed that the LCLUC, due to the changes in relevant surface variables, has caused alterations in local and neighborhood regions climate. The LCLUC leads to a decrease in mean rainfall during dry season at study area. A meridional dipole pattern with near surface temperature increase (reduction) in the northern (southern) areas of semiarid was found. The results also highlight that LUCC led to changes in the components of the surface energy and carbon balance. These results suggest that LCLUC, even on a small scale in Brazil's semiarid region, can cause climate impacts, in local and regional scale. Finally, we highlight that the diagnosis of the evolution of LUCC and its climatic implications are essential to guide policy makers in regard to resources application and on policies development, in order to achieve a better management and planning for this important region of the country.

Vertical patterns and controls of soil nutrients in alpine grassland: Implications for nutrient uptake.

PubMed

Tian, Liming; Zhao, Lin; Wu, Xiaodong; Fang, Hongbing; Zhao, Yonghua; Yue, Guangyang; Liu, Guimin; Chen, Hao

2017-12-31

Vertical patterns and determinants of soil nutrients are critical to understand nutrient cycling in high-altitude ecosystems; however, they remain poorly understood in the alpine grassland due to lack of systematic field observations. In this study, we examined vertical distributions of soil nutrients and their influencing factors within the upper 1m of soil, using data of 68 soil profiles surveyed in the alpine grassland of the eastern Qinghai-Tibet Plateau. Soil organic carbon (SOC) and total nitrogen (TN) stocks decreased with depth in both alpine meadow (AM) and alpine steppe (AS), but remain constant along the soil profile in alpine swamp meadow (ASM). Total phosphorus, Ca 2+ , and Mg 2+ stocks slightly increased with depth in ASM. K + stock decreased with depth, while Na + stock increased slightly with depth among different vegetation types; however, SO 4 2- and Cl - stocks remained relatively uniform throughout different depth intervals in the alpine grassland. Except for SOC and TN, soil nutrient stocks in the top 20cm soils were significantly lower in ASM compared to those in AM and AS. Correlation analyses showed that SOC and TN stocks in the alpine grassland positively correlated with vegetation coverage, soil moisture, clay content, and silt content, while they negatively related to sand content and soil pH. However, base cation stocks revealed contrary relationships with those environmental variables compared to SOC and TN stocks. These correlations varied between vegetation types. In addition, no significant relationship was detected between topographic factors and soil nutrients. Our findings suggest that plant cycling and soil moisture primarily control vertical distributions of soil nutrients (e.g. K) in the alpine grassland and highlight that vegetation types in high-altitude permafrost regions significantly affect soil nutrients. Copyright © 2017 Elsevier B.V. All rights reserved.

Climate refugia: The physical, hydrologic and disturbance basis

NASA Astrophysics Data System (ADS)

Holden, Z. A.; Maneta, M. P.; Forthofer, J.

2015-12-01

Projected changes in global climate and associated shifts in vegetation have increased interest in understanding species persistence at local scales. We examine the climatic and physical factors that could mediate changes in the distribution of vegetation in regions of complex topography. Using massive networks of low-cost temperature and humidity sensors, we developed topographically-resolved daily historical gridded temperature data for the US Northern Rockies. We used the WindNinja model to create daily historical wind speed maps across the same domain. Using a spatially distributed ecohydrology model (ECH2O) we examine separately the sensitivity of modeled evapotranspiration and soil moisture to wind, radiation, soil properties, minimum temperature and humidity. A suite of physical factors including lower wind speeds, cold air drainage, solar shading and increased soil depth reduce evapotranspiration and increase late season moisture availability in valley bottoms. Evapotranspiration shows strong sensitivity to spatial variability in surface wind speed, suggesting that sheltering effects from winds may be an important factor contributing to mountain refugia. Fundamental to our understanding of patterns of vegetation change is the role of stand-replacing wildfires, which modify the physical environment and subsequent patterns of species persistence and recruitment. Using satellite-derived maps of burn severity for recent fires in the US Northern Rockies we examined relationships between wind speed, cold air drainage potential and soil depth and the occurrence of unburned and low severity fire. Severe fire is less likely to occur in areas with high cold air drainage potential and low wind speeds, suggesting that sheltered valley bottoms have mediated the severity of recent wildfires. Our finding highlight the complex physical mechanisms by which mountain weather and climate mediate fire-induced vegetation changes in the US Northern Rocky Mountains.

Multiple remote sensing data sources to assess spatio-temporal patterns of fire incidence over Campos Amazônicos Savanna Vegetation Enclave (Brazilian Amazon).

PubMed

Alves, Daniel Borini; Pérez-Cabello, Fernando

2017-12-01

Fire activity plays an important role in the past, present and future of Earth system behavior. Monitoring and assessing spatial and temporal fire dynamics have a fundamental relevance in the understanding of ecological processes and the human impacts on different landscapes and multiple spatial scales. This work analyzes the spatio-temporal distribution of burned areas in one of the biggest savanna vegetation enclaves in the southern Brazilian Amazon, from 2000 to 2016, deriving information from multiple remote sensing data sources (Landsat and MODIS surface reflectance, TRMM pluviometry and Vegetation Continuous Field tree cover layers). A fire scars database with 30 m spatial resolution was generated using a Landsat time series. MODIS daily surface reflectance was used for accurate dating of the fire scars. TRMM pluviometry data were analyzed to dynamically establish time limits of the yearly dry season and burning periods. Burned area extent, frequency and recurrence were quantified comparing the results annually/seasonally. Additionally, Vegetation Continuous Field tree cover layers were used to analyze fire incidence over different types of tree cover domains. In the last seventeen years, 1.03millionha were burned within the study area, distributed across 1432 fire occurrences, highlighting 2005, 2010 and 2014 as the most affected years. Middle dry season fires represent 86.21% of the total burned areas and 32.05% of fire occurrences, affecting larger amount of higher density tree surfaces than other burning periods. The results provide new insights into the analysis of burned areas of the neotropical savannas, spatially and statistically reinforcing important aspects linked to the seasonality patterns of fire incidence in this landscape. Copyright © 2017 Elsevier B.V. All rights reserved.

[Dynamics of carbon and nitrogen storage of Cupressus chengiana plantations in the arid valley of Minjiang River, Southwest China].

PubMed

Luo, Da; Feng, Qiu-hong; Shi, Zuo-min; Li, Dong-sheng; Yang, Chang-xu; Liu, Qian-li; He, Jian-she

2015-04-01

The carbon and nitrogen storage and distribution patterns of Cupressus chengiana plantation ecosystems with different stand ages in the arid valley of Minjiang River were studied. The results showed that carbon contents in different organs of C. chengiana were relatively stable, while nitrogen contents were closely related to different organs, and soil organic carbon and nitrogen contents increased with the stand age. Carbon and nitrogen storage in vegetation layer, soil layer, and the whole ecosystem of the plantation increased with the stand age. The values of total carbon storage in the 13-, 11-, 8-, 6- and 4-year-old C. chengiana plantation ecosystems were 190.90, 165.91, 144.57, 119.44, and 113.49 t x hm(-2), and the values of total nitrogen storage were 19.09, 17.97, 13.82, 13.42, and 12.26 t x hm(-2), respectively. Most of carbon and nitrogen were stored in the 0-60 cm soil layer in the plantation ecosystems and occupied 92.8% and 98.8%, respectively, and the amounts of carbon and nitrogen stored in the top 0-20 cm soil layer, accounted for 54.4% and 48.9% of those in the 0-60 cm soil layer, respectively. Difference in distribution of carbon and nitrogen storage was observed in the vegetation layer. The percentage of carbon storage in tree layer (3.7%) were higher than that in understory vegetation (3.5%), while the percentage of nitrogen storage in tree layer (0.5%) was lower than that in understory (0.7%). The carbon and nitrogen storage and distribution patterns in the plantations varied obviously with the stand age, and the plantation ecosystems at these age stages could accumulate organic carbon and nitrogen continuously.

How landscape dynamics link individual- to population-level movement patterns: A multispecies comparison of ungulate relocation data

USGS Publications Warehouse

Mueller, Thomas; Olson, K.A.; Dressler, G.; Leimgruber, Peter; Fuller, Todd K.; Nicholson, Craig; Novaro, A.J.; Bolgeri, M.J.; Wattles, David W.; DeStefano, Stephen; Calabrese, J.M.; Fagan, William F.

2011-01-01

Aim  To demonstrate how the interrelations of individual movements form large-scale population-level movement patterns and how these patterns are associated with the underlying landscape dynamics by comparing ungulate movements across species.Locations  Arctic tundra in Alaska and Canada, temperate forests in Massachusetts, Patagonian Steppes in Argentina, Eastern Steppes in Mongolia.Methods  We used relocation data from four ungulate species (barren-ground caribou, Mongolian gazelle, guanaco and moose) to examine individual movements and the interrelation of movements among individuals. We applied and developed a suite of spatial metrics that measure variation in movement among individuals as population dispersion, movement coordination and realized mobility. Taken together, these metrics allowed us to quantify and distinguish among different large-scale population-level movement patterns such as migration, range residency and nomadism. We then related the population-level movement patterns to the underlying landscape vegetation dynamics via long-term remote sensing measurements of the temporal variability, spatial variability and unpredictability of vegetation productivity.Results  Moose, which remained in sedentary home ranges, and guanacos, which were partially migratory, exhibited relatively short annual movements associated with landscapes having very little broad-scale variability in vegetation. Caribou and gazelle performed extreme long-distance movements that were associated with broad-scale variability in vegetation productivity during the peak of the growing season. Caribou exhibited regular seasonal migration in which individuals were clustered for most of the year and exhibited coordinated movements. In contrast, gazelle were nomadic, as individuals were independently distributed and moved in an uncoordinated manner that relates to the comparatively unpredictable (yet broad-scale) vegetation dynamics of their landscape.Main conclusions  We show how broad-scale landscape unpredictability may lead to nomadism, an understudied type of long-distance movement. In contrast to classical migration where landscapes may vary at broad scales but in a predictable manner, long-distance movements of nomadic individuals are uncoordinated and independent from other such individuals. Landscapes with little broad-scale variability in vegetation productivity feature smaller-scale movements and allow for range residency. Nomadism requires distinct integrative conservation strategies that facilitate long-distance movements across the entire landscape and are not limited to certain migration corridors.

How landscape dynamics link individual- to population-level movement patterns: A multispecies comparison of ungulate relocation data

USGS Publications Warehouse

Mueller, T.; Olson, K.A.; Dressler, G.; Leimgruber, P.; Fuller, T.K.; Nicolson, C.; Novaro, A.J.; Bolgeri, M.J.; Wattles, David W.; DeStefano, S.; Calabrese, J.M.; Fagan, W.F.

2011-01-01

Aim To demonstrate how the interrelations of individual movements form large-scale population-level movement patterns and how these patterns are associated with the underlying landscape dynamics by comparing ungulate movements across species. Locations Arctic tundra in Alaska and Canada, temperate forests in Massachusetts, Patagonian Steppes in Argentina, Eastern Steppes in Mongolia. Methods We used relocation data from four ungulate species (barren-ground caribou, Mongolian gazelle, guanaco and moose) to examine individual movements and the interrelation of movements among individuals. We applied and developed a suite of spatial metrics that measure variation in movement among individuals as population dispersion, movement coordination and realized mobility. Taken together, these metrics allowed us to quantify and distinguish among different large-scale population-level movement patterns such as migration, range residency and nomadism. We then related the population-level movement patterns to the underlying landscape vegetation dynamics via long-term remote sensing measurements of the temporal variability, spatial variability and unpredictability of vegetation productivity. Results Moose, which remained in sedentary home ranges, and guanacos, which were partially migratory, exhibited relatively short annual movements associated with landscapes having very little broad-scale variability in vegetation. Caribou and gazelle performed extreme long-distance movements that were associated with broad-scale variability in vegetation productivity during the peak of the growing season. Caribou exhibited regular seasonal migration in which individuals were clustered for most of the year and exhibited coordinated movements. In contrast, gazelle were nomadic, as individuals were independently distributed and moved in an uncoordinated manner that relates to the comparatively unpredictable (yet broad-scale) vegetation dynamics of their landscape. Main conclusions We show how broad-scale landscape unpredictability may lead to nomadism, an understudied type of long-distance movement. In contrast to classical migration where landscapes may vary at broad scales but in a predictable manner, long-distance movements of nomadic individuals are uncoordinated and independent from other such individuals. Landscapes with little broad-scale variability in vegetation productivity feature smaller-scale movements and allow for range residency. Nomadism requires distinct integrative conservation strategies that facilitate long-distance movements across the entire landscape and are not limited to certain migration corridors. ?? 2011 Blackwell Publishing Ltd.

Response of spatial vegetation distribution in China to climate changes since the Last Glacial Maximum (LGM)

PubMed Central

Wang, Siyang; Xu, Xiaoting; Shrestha, Nawal; Zimmermann, Niklaus E.; Tang, Zhiyao; Wang, Zhiheng

2017-01-01

Analyzing how climate change affects vegetation distribution is one of the central issues of global change ecology as this has important implications for the carbon budget of terrestrial vegetation. Mapping vegetation distribution under historical climate scenarios is essential for understanding the response of vegetation distribution to future climatic changes. The reconstructions of palaeovegetation based on pollen data provide a useful method to understand the relationship between climate and vegetation distribution. However, this method is limited in time and space. Here, using species distribution model (SDM) approaches, we explored the climatic determinants of contemporary vegetation distribution and reconstructed the distribution of Chinese vegetation during the Last Glacial Maximum (LGM, 18,000 14C yr BP) and Middle-Holocene (MH, 6000 14C yr BP). The dynamics of vegetation distribution since the LGM reconstructed by SDMs were largely consistent with those based on pollen data, suggesting that the SDM approach is a useful tool for studying historical vegetation dynamics and its response to climate change across time and space. Comparison between the modeled contemporary potential natural vegetation distribution and the observed contemporary distribution suggests that temperate deciduous forests, subtropical evergreen broadleaf forests, temperate deciduous shrublands and temperate steppe have low range fillings and are strongly influenced by human activities. In general, the Tibetan Plateau, North and Northeast China, and the areas near the 30°N in Central and Southeast China appeared to have experienced the highest turnover in vegetation due to climate change from the LGM to the present. PMID:28426780

Synoptic and Mesoscale Climatologies of Severe Local Storms for the American Midwest.

NASA Astrophysics Data System (ADS)

Arnold, David Leslie

This study investigates the synoptic and mesoscale environments associated with severe local storms (SELS) in the heart of the American Midwest. This region includes west-central Illinois, most of Indiana, the extreme western counties of Ohio, and a small part of northeastern Kentucky. The primary objectives of this study are to determine the surface and middle-tropospheric synoptic circulation patterns and thermodynamic and kinematic environments associated with SELS event types (tornadoes, hail, severe straight -line winds), and to assess the degree to which the synoptic circulation patterns and meso-beta scale kinematic and thermodynamic climatology of the Midwest differ from that of the Great Plains. A secondary objective is to investigate the possible role that land-surface atmosphere interactions play in the spatial distribution of SELS. A new subjective synoptic typing scheme is developed and applied to determine the synoptic-scale circulation patterns associated with the occurrence of SELS event types. This scheme is based on a combination of surface and middle -tropospheric patterns. Thermodynamic and kinematic parameters are analyzed to determine meso-scale environments favorable for the development of SELS. Results indicate that key synoptic-scale circulation patterns, and specific ranges of thermodynamic and kinematic parameters are related to specific SELS event types. These circulation types and ranges of thermodynamic and kinematic parameters may be used to help improve the medium-range forecasting of severe local storms. Results of the secondary objective reveal that the spatial distribution of SELS events is clustered within the study region, and most occur under a negative climate division-level soil moisture gradient; that is, a drier upwind division than the division in which the event occurs. Moreover, the spatial distribution of SELS events is compared against a map of soil types and vegetation. The resulting distribution depicts a visual correlation between the primary soil and vegetative boundaries and clusters of SELS. This supports the likely role of meso-scale land-surface-atmosphere interactions in severe weather development for humid lowlands of the Midwest United States.

Feedback of observed interannual vegetation change: a regional climate model analysis for the West African monsoon

NASA Astrophysics Data System (ADS)

Klein, Cornelia; Bliefernicht, Jan; Heinzeller, Dominikus; Gessner, Ursula; Klein, Igor; Kunstmann, Harald

2017-05-01

West Africa is a hot spot region for land-atmosphere coupling where atmospheric conditions and convective rainfall can strongly depend on surface characteristics. To investigate the effect of natural interannual vegetation changes on the West African monsoon precipitation, we implement satellite-derived dynamical datasets for vegetation fraction (VF), albedo and leaf area index into the Weather Research and Forecasting model. Two sets of 4-member ensembles with dynamic and static land surface description are used to extract vegetation-related changes in the interannual difference between August-September 2009 and 2010. The observed vegetation patterns retain a significant long-term memory of preceding rainfall patterns of at least 2 months. The interannual vegetation changes exhibit the strongest effect on latent heat fluxes and associated surface temperatures. We find a decrease (increase) of rainy hours over regions with higher (lower) VF during the day and the opposite during the night. The probability that maximum precipitation is shifted to nighttime (daytime) over higher (lower) VF is 12 % higher than by chance. We attribute this behaviour to horizontal circulations driven by differential heating. Over more vegetated regions, the divergence of moist air together with lower sensible heat fluxes hinders the initiation of deep convection during the day. During the night, mature convective systems cause an increase in the number of rainy hours over these regions. We identify this feedback in both water- and energy-limited regions of West Africa. The inclusion of observed dynamical surface information improved the spatial distribution of modelled rainfall in the Sahel with respect to observations, illustrating the potential of satellite data as a boundary constraint for atmospheric models.

Global vegetation productivity response to climatic oscillations during the satellite era.

PubMed

Gonsamo, Alemu; Chen, Jing M; Lombardozzi, Danica

2016-10-01

Climate control on global vegetation productivity patterns has intensified in response to recent global warming. Yet, the contributions of the leading internal climatic variations to global vegetation productivity are poorly understood. Here, we use 30 years of global satellite observations to study climatic variations controls on continental and global vegetation productivity patterns. El Niño-Southern Oscillation (ENSO) phases (La Niña, neutral, and El Niño years) appear to be a weaker control on global-scale vegetation productivity than previously thought, although continental-scale responses are substantial. There is also clear evidence that other non-ENSO climatic variations have a strong control on spatial patterns of vegetation productivity mainly through their influence on temperature. Among the eight leading internal climatic variations, the East Atlantic/West Russia Pattern extensively controls the ensuing year vegetation productivity of the most productive tropical and temperate forest ecosystems of the Earth's vegetated surface through directionally consistent influence on vegetation greenness. The Community Climate System Model (CCSM4) simulations do not capture the observed patterns of vegetation productivity responses to internal climatic variations. Our analyses show the ubiquitous control of climatic variations on vegetation productivity and can further guide CCSM and other Earth system models developments to represent vegetation response patterns to unforced variability. Several winter time internal climatic variation indices show strong potentials on predicting growing season vegetation productivity two to six seasons ahead which enables national governments and farmers forecast crop yield to ensure supplies of affordable food, famine early warning, and plan management options to minimize yield losses ahead of time. © 2016 John Wiley & Sons Ltd.

Dynamics Change of Vegetated Lands in A Highway Corridor during 37 Years (Case study of Jagorawi Toll Road, Jakarta-Bogor)

NASA Astrophysics Data System (ADS)

Perdana, B. P.; Setiawan, Y.; Prasetyo, L. B.

2018-02-01

Recently, a highway development is required as a liaison between regions to support the economic development of the regions. Even the availability of highways give positive impacts, it also has negative impacts, especially related to the changes of vegetated lands. This study aims to determine the change of vegetation coverage in Jagorawi corridor Jakarta-Bogor during 37 years, and to analyze landscape patterns in the corridor based on distance factor from Jakarta to Bogor. In this study, we used a long-series of Landsat images taken by Landsat 2 MSS (1978), Landsat 5 TM (1988, 1995, and 2005) and Landsat 8 OLI/TIRS (2015). Analysis of landscape metrics was conducted through patch analysis approach to determine the change of landscape patterns in the Jagorawi corridor Jakarta-Bogor. Several parameters of landscape metrics used are Number of Patches (NumP), Mean Patch Size (MPS), Mean Shape Index (MSI), and Edge Density (ED). These parameters can be used to provide information of structural elements of landscape, composition and spatial distribution in the corridor. The results indicated that vegetation coverage in the Jagorawi corridor Jakarta-Bogor decreased about 48% for 35 years. Moreover, NumP value increased and decreasing of MPS value as a means of higher fragmentation level occurs with patch size become smaller. Meanwhile, The increase in ED parameters indicates that vegetated land is damaged annually. MSI parameter shows a decrease in every year which means land degradation on vegetated land. This indicates that the declining value of MSI will have an impact on land degradation.

Historical and current forest landscapes of eastern Oregon and Washington Part I: Vegetation pattern and insect and disease hazards.

Treesearch

J.F. Lehmkuhl; P.F. Hessburg; R.L. Everett; M.H. Huff; R.D. Ottmar

1994-01-01

We analyzed historical and current vegetation composition and structure in 49 sample watersheds, primarily on National Forests, within six river basins in eastern Oregon and Washington. Vegetation patterns were mapped from aerial photographs taken from 1932 to 1959, and from 1985 to 1992. We described vegetation attributes, landscape patterns, the range of historical...

Vegetation and non-native ungulate monitoring at the Big Island National Wildlife Refuge Complex 2010–2014.

USGS Publications Warehouse

Hess, Steven C.; Leopold, Christina R.; Kendall, Steven J.

2015-01-01

The Hakalau Forest Unit (HFU) of Big Island National Wildlife Refuge Complex (BINWRC) has intensively managed feral cattle (Bos taurus) and pigs (Sus scrofa) and monitored non-native ungulate presence and distribution during surveys of all managed areas since 1988. We: 1) provide results from recent ungulate surveys at HFU to determine current feral pig abundance and distribution; 2) present results of surveys of ungulate presence and distribution at the Kona Forest Unit (KFU); 3) present results of surveys of weed presence and cover at both refuge units; and 4) present baseline results from long-term vegetation monitoring plots at KFU. Overall pig abundance appears to have decreased at HFU, although not significantly, over the period from 2010 to 2014. Management units 2 and 4 contained the majority of pigs at HFU. Pig density outside of adjacent managed areas has declined significantly from 2010 to 2014 for unknown reasons. Ungulate sign occurred in > 50% of plots at KFU during the November 2012 and September 2013 surveys, but ungulate sign occurred in < 28% of plots during three other surveys. The ability to differentiate sign of ungulate species remains problematic at KFU. Changes in weed cover do not yet demonstrate any strong temporal pattern. Spatial patterns are more pronounced; however, some weed species may not be reliably represented due to observers’ abilities to recognize less common weeds. Nonetheless, the distribution and cover of fireweed (Senecio madagascariensis) at KFU may have increased over the study period. Vegetation surveys documented baseline floristic composition and forest structure at KFU. It is not known if this current amount of emerging cover is sufficient for long-term self-sustaining forest canopy regeneration; however, numerous ‘ōhi‘a seedlings were found in the wet forest and mesic ‘ōhi‘a habitats, indicating an ample viable seed source and robust potential for forest regeneration.

Development and assessment of 30-meter pine density maps for landscape-level modeling of mountain pine beetle dynamics

Treesearch

Benjamin A. Crabb; James A. Powell; Barbara J. Bentz

2012-01-01

Forecasting spatial patterns of mountain pine beetle (MPB) population success requires spatially explicit information on host pine distribution. We developed a means of producing spatially explicit datasets of pine density at 30-m resolution using existing geospatial datasets of vegetation composition and structure. Because our ultimate goal is to model MPB population...

Using satellite and airborne LiDAR to model woodpecker habitat occupancy at the landscape scale

Treesearch

Lee A. Vierling; Kerri T. Vierling; Patrick Adam; Andrew T. Hudak

2013-01-01

Incorporating vertical vegetation structure into models of animal distributions can improve understanding of the patterns and processes governing habitat selection. LiDAR can provide such structural information, but these data are typically collected via aircraft and thus are limited in spatial extent. Our objective was to explore the utility of satellite-based LiDAR...

Root biomass along subtropical to alpine gradients: global implication from Tibetan transect studies

Treesearch

Tianxiang Luo; Sandra Brown; Yude Pan; Peili Shi; Hua Ouyang; Zhenliang Yu; Huazhong Zhu

2005-01-01

Much uncertainty in estimating root biomass density (RBD, root mass per unit area) of all roots regionally exists because of methodological difficulties and little knowledge about the effects of biotic and abiotic factors on the magnitude and distribution pattern of RBD. In this study, we collected field data of RBD from 22 sites along the Tibetan Alpine Vegetation...

Oak Forest Composition, Site Quality, and Dynamics in Relation to Site Factors in the Southeastern Missouri Ozarks

Treesearch

John M. Kabrick; Stephen R. Shifley; Randy G. Jensen; David R. Larsen; Jennifer K. Grabner

2004-01-01

Physical site factors are known to affect forest species composition but the pattern and variation across forest landscapes has not been well quantified. We discuss relationships between site factors including soil parent materials, depth to dolomite bedrock, aspect, and landform position and the distribution of vegetation, site index, and short-term succession in oak...

Vegetation responsees to landscape structure at multiple scales across a Northern Wisconsin, USA, pine barrens landscape

Treesearch

K.D. Brosofske; J. Chen; Thomas R. Crow; S.C. Saunders

1999-01-01

Increasing awareness of the importance of scale and landscape structure to landscape processes and concern about loss of biodiversity has resulted in efforts to understand patterns of biodiversity across multiple scales. We examined plant species distributions and their relationships to landscape structure at varying spatial scales across a pine barrens landscape in...

Modeling climate changes and wildfire interactions: Effects on whitebark pine (Pinus albicaulis) and implications for restoration, Glacier National Park, Montana, USA

Treesearch

Rachel A. Loehman; Allissa Corrow; Robert E. Keane

2011-01-01

Climate changes are projected to profoundly influence vegetation patterns and community compositions, either directly through increased species mortality and shifts in species distributions, or indirectly through disturbance dynamics such as increased wildfire activity and extent, shifting fire regimes, and pathogenesis. High-elevation landscapes have been shown to be...

Shifts in controls on the temporal coherence of throughfall chemical flux in Acadia National Park, Maine, USA

USGS Publications Warehouse

Nelson, Sarah J.; Webster, Katherine E.; Loftin, Cynthia S.; Weathers, Kathleen C.

2013-01-01

Major ion and mercury (Hg) inputs to terrestrial ecosystems include both wet and dry deposition (total deposition). Estimating total deposition to sensitive receptor sites is hampered by limited information regarding its spatial heterogeneity and seasonality. We used measurements of throughfall flux, which includes atmospheric inputs to forests and the net effects of canopy leaching or uptake, for ten major ions and Hg collected during 35 time periods in 1999–2005 at over 70 sites within Acadia National Park, Maine to (1) quantify coherence in temporal dynamics of seasonal throughfall deposition and (2) examine controls on these patterns at multiple scales. We quantified temporal coherence as the correlation between all possible site pairs for each solute on a seasonal basis. In the summer growing season and autumn, coherence among pairs of sites with similar vegetation was stronger than for site-pairs that differed in vegetation suggesting that interaction with the canopy and leaching of solutes differed in coniferous, deciduous, mixed, and shrub or open canopy sites. The spatial pattern in throughfall hydrologic inputs across Acadia National Park was more variable during the winter snow season, suggesting that snow re-distribution affects net hydrologic input, which consequently affects chemical flux. Sea-salt corrected calcium concentrations identified a shift in air mass sources from maritime in winter to the continental industrial corridor in summer. Our results suggest that the spatial pattern of throughfall hydrologic flux, dominant seasonal air mass source, and relationship with vegetation in winter differ from the spatial pattern of throughfall flux in these solutes in summer and autumn. The coherence approach applied here made clear the strong influence of spatial heterogeneity in throughfall hydrologic inputs and a maritime air mass source on winter patterns of throughfall flux. By contrast, vegetation type was the most important influence on throughfall chemical flux in summer and autumn.

Patterns in woody vegetation structure across African savannas

NASA Astrophysics Data System (ADS)

Axelsson, Christoffer R.; Hanan, Niall P.

2017-07-01

Vegetation structure in water-limited systems is to a large degree controlled by ecohydrological processes, including mean annual precipitation (MAP) modulated by the characteristics of precipitation and geomorphology that collectively determine how rainfall is distributed vertically into soils or horizontally in the landscape. We anticipate that woody canopy cover, crown density, crown size, and the level of spatial aggregation among woody plants in the landscape will vary across environmental gradients. A high level of woody plant aggregation is most distinct in periodic vegetation patterns (PVPs), which emerge as a result of ecohydrological processes such as runoff generation and increased infiltration close to plants. Similar, albeit weaker, forces may influence the spatial distribution of woody plants elsewhere in savannas. Exploring these trends can extend our knowledge of how semi-arid vegetation structure is constrained by rainfall regime, soil type, topography, and disturbance processes such as fire. Using high-spatial-resolution imagery, a flexible classification framework, and a crown delineation method, we extracted woody vegetation properties from 876 sites spread over African savannas. At each site, we estimated woody cover, mean crown size, crown density, and the degree of aggregation among woody plants. This enabled us to elucidate the effects of rainfall regimes (MAP and seasonality), soil texture, slope, and fire frequency on woody vegetation properties. We found that previously documented increases in woody cover with rainfall is more consistently a result of increasing crown size than increasing density of woody plants. Along a gradient of mean annual precipitation from the driest (< 200 mm yr-1) to the wettest (1200-1400 mm yr-1) end, mean estimates of crown size, crown density, and woody cover increased by 233, 73, and 491 % respectively. We also found a unimodal relationship between mean crown size and sand content suggesting that maximal savanna tree sizes do not occur in either coarse sands or heavy clays. When examining the occurrence of PVPs, we found that the same factors that contribute to the formation of PVPs also correlate with higher levels of woody plant aggregation elsewhere in savannas and that rainfall seasonality plays a key role for the underlying processes.

Plant functional types in Earth system models: past experiences and future directions for application of dynamic vegetation models in high-latitude ecosystems.

PubMed

Wullschleger, Stan D; Epstein, Howard E; Box, Elgene O; Euskirchen, Eugénie S; Goswami, Santonu; Iversen, Colleen M; Kattge, Jens; Norby, Richard J; van Bodegom, Peter M; Xu, Xiaofeng

2014-07-01

Earth system models describe the physical, chemical and biological processes that govern our global climate. While it is difficult to single out one component as being more important than another in these sophisticated models, terrestrial vegetation is a critical player in the biogeochemical and biophysical dynamics of the Earth system. There is much debate, however, as to how plant diversity and function should be represented in these models. Plant functional types (PFTs) have been adopted by modellers to represent broad groupings of plant species that share similar characteristics (e.g. growth form) and roles (e.g. photosynthetic pathway) in ecosystem function. In this review, the PFT concept is traced from its origin in the early 1800s to its current use in regional and global dynamic vegetation models (DVMs). Special attention is given to the representation and parameterization of PFTs and to validation and benchmarking of predicted patterns of vegetation distribution in high-latitude ecosystems. These ecosystems are sensitive to changing climate and thus provide a useful test case for model-based simulations of past, current and future distribution of vegetation. Models that incorporate the PFT concept predict many of the emerging patterns of vegetation change in tundra and boreal forests, given known processes of tree mortality, treeline migration and shrub expansion. However, representation of above- and especially below-ground traits for specific PFTs continues to be problematic. Potential solutions include developing trait databases and replacing fixed parameters for PFTs with formulations based on trait co-variance and empirical trait-environment relationships. Surprisingly, despite being important to land-atmosphere interactions of carbon, water and energy, PFTs such as moss and lichen are largely absent from DVMs. Close collaboration among those involved in modelling with the disciplines of taxonomy, biogeography, ecology and remote sensing will be required if we are to overcome these and other shortcomings. Published by Oxford University Press on behalf of the Annals of Botany Company 2014. This work is written by (a) US Government employee(s) and is in the public domain in the US.

Floodplain Vegetation Dynamics Modeling Using Coupled RiPCAS-DFLOW (CoRD): Jemez Canyon, Jemez River, New Mexico

NASA Astrophysics Data System (ADS)

Miller, S. J.; Gregory, A. E.; Turner, M. A.; Chaulagain, S.; Cadol, D.; Stone, M. C.; Sheneman, L.

2017-12-01

Interactions among precipitation, vegetation, soil moisture, runoff and other landscape properties set the stage for complex streamflow regimes and cascading riparian habitat impacts, particularly in semi-arid regions. A consortium of New Mexico, Nevada, and Idaho, funded through NSF-EPSCoR, has promulgated the Western Consortium for Watershed Analysis, Visualization, and Exploration (WC-WAVE). Two WC-WAVE objectives are to advance understanding of hydrologic interactions and ecosystem services, and to develop a virtual watershed platform (VWP) cyber-infrastructure to unite and streamline coordination among teams, databases and modeling tools. To provide proof of concept for the VWP and to study coevolution of riparian habitat mosaics and flood dynamics, the study team selected two models and developed a model coupling system for the Jemez River Canyon, Jemez River, NM. DFLOW is a 2-D hydrodynamic model for steady and unsteady flow conditions; the Riparian Community Alteration and Succession (RipCAS) model, developed using concepts from a vegetation disturbance and succession model (CASiMiR), uses shear stresses and flood depths from DFLOW to evolve riparian vegetation maps with associated roughness. The Coupled RipCAS-DFLOW (CoRD) model allows serial annual time step feedback of changes in peak-flow-derived depth and shear stress and vegetation-derived roughness values. An intuitive command-line interface on a computing cluster is used to call CoRD, which provides commands to calculate boundary conditions, perform multiple file and data format conversions and archive and compress decades of data. Four thirty-year synthetic annual maximum flood scenarios were selected for CoRD simulations, representing a historical wet period (1957-1986) a historical dry period (1986-2015), and flows doubling the historical wet period and halving the historical dry period. Event-driven coupled modeling simulates the spatial distribution of floodplain vegetation community evolution over decades of flood record. Implications for riparian habitat distribution patterns under changing streamflow regimes due to increased fire and climate change, shifting landuse and livestock access patterns, and management of invasive exotic species are considered in interpreting experimental model scenarios.

Characterizing the spatial structure of endangered species habitat using geostatistical analysis of IKONOS imagery

USGS Publications Warehouse

Wallace, C.S.A.; Marsh, S.E.

2005-01-01

Our study used geostatistics to extract measures that characterize the spatial structure of vegetated landscapes from satellite imagery for mapping endangered Sonoran pronghorn habitat. Fine spatial resolution IKONOS data provided information at the scale of individual trees or shrubs that permitted analysis of vegetation structure and pattern. We derived images of landscape structure by calculating local estimates of the nugget, sill, and range variogram parameters within 25 ?? 25-m image windows. These variogram parameters, which describe the spatial autocorrelation of the 1-m image pixels, are shown in previous studies to discriminate between different species-specific vegetation associations. We constructed two independent models of pronghorn landscape preference by coupling the derived measures with Sonoran pronghorn sighting data: a distribution-based model and a cluster-based model. The distribution-based model used the descriptive statistics for variogram measures at pronghorn sightings, whereas the cluster-based model used the distribution of pronghorn sightings within clusters of an unsupervised classification of derived images. Both models define similar landscapes, and validation results confirm they effectively predict the locations of an independent set of pronghorn sightings. Such information, although not a substitute for field-based knowledge of the landscape and associated ecological processes, can provide valuable reconnaissance information to guide natural resource management efforts. ?? 2005 Taylor & Francis Group Ltd.

Realized niche width of a brackish water submerged aquatic vegetation under current environmental conditions and projected influences of climate change.

PubMed

Kotta, Jonne; Möller, Tiia; Orav-Kotta, Helen; Pärnoja, Merli

2014-12-01

Little is known about how organisms might respond to multiple climate stressors and this lack of knowledge limits our ability to manage coastal ecosystems under contemporary climate change. Ecological models provide managers and decision makers with greater certainty that the systems affected by their decisions are accurately represented. In this study Boosted Regression Trees modelling was used to relate the cover of submerged aquatic vegetation to the abiotic environment in the brackish Baltic Sea. The analyses showed that the majority of the studied submerged aquatic species are most sensitive to changes in water temperature, current velocity and winter ice scour. Surprisingly, water salinity, turbidity and eutrophication have little impact on the distributional pattern of the studied biota. Both small and large scale environmental variability contributes to the variability of submerged aquatic vegetation. When modelling species distribution under the projected influences of climate change, all of the studied submerged aquatic species appear to be very resilient to a broad range of environmental perturbation and biomass gains are expected when seawater temperature increases. This is mainly because vegetation develops faster in spring and has a longer growing season under the projected climate change scenario. Copyright © 2014 Elsevier Ltd. All rights reserved.

Vegetation sensitivity to global anthropogenic carbon dioxide emissions in a topographically complex region

USGS Publications Warehouse

Diffenbaugh, N.S.; Sloan, L.C.; Snyder, M.A.; Bell, J.L.; Kaplan, J.; Shafer, S.L.; Bartlein, P.J.

2003-01-01

Anthropogenic increases in atmospheric carbon dioxide (CO2) concentrations may affect vegetation distribution both directly through changes in photosynthesis and water-use efficiency, and indirectly through CO2-induced climate change. Using an equilibrium vegetation model (BIOME4) driven by a regional climate model (RegCM2.5), we tested the sensitivity of vegetation in the western United States, a topographically complex region, to the direct, indirect, and combined effects of doubled preindustrial atmospheric CO2 concentrations. Those sensitivities were quantified using the kappa statistic. Simulated vegetation in the western United States was sensitive to changes in atmospheric CO2 concentrations, with woody biome types replacing less woody types throughout the domain. The simulated vegetation was also sensitive to climatic effects, particularly at high elevations, due to both warming throughout the domain and decreased precipitation in key mountain regions such as the Sierra Nevada of California and the Cascade and Blue Mountains of Oregon. Significantly, when the direct effects of CO2 on vegetation were tested in combination with the indirect effects of CO2-induced climate change, new vegetation patterns were created that were not seen in either of the individual cases. This result indicates that climatic and nonclimatic effects must be considered in tandem when assessing the potential impacts of elevated CO2 levels.

Improving Long-term Post-wildfire hydrologic simulations using ParFlow

NASA Astrophysics Data System (ADS)

Lopez, S. R.; Kinoshita, A. M.

2015-12-01

Wildfires alter the natural hydrologic processes within a watershed. After vegetation is burned, the combustion of organic material and debris settles into the soil creating a hydrophobic layer beneath the soil surface with varying degree of thickness and depth. Vegetation regrowth rates vary as a function of radiative exposure, burn severity, and precipitation patterns. Hydrologic models used by the Burned Area Emergency Response (BAER) teams use input data and model calibration constraints that are generally either one-dimensional, empirically-based models, or two-dimensional, conceptually-based models with lumped parameter distributions. These models estimate runoff measurements at the watershed outlet; however, do not provide a distributed hydrologic simulation at each point within the watershed. This work uses ParFlow, a three-dimensional, distributed hydrologic model to (1) correlate burn severity with hydrophobicity, (2) evaluate vegetation recovery rate on water components, and (3) improve flood prediction for managers to help with resource allocation and management operations in burned watersheds. ParFlow is applied to Devil Canyon (43 km2) in San Bernardino, California, which was 97% burned in the 2003 Old Fire. The model set-up uses a 30m-cell size resolution over a 6.7 km by 6.4 km lateral extent. The subsurface reaches 30 m and is assigned a variable cell thickness. Variable subsurface thickness allows users to explicitly consider the degree of recovery throughout the stages of regrowth. Burn severity maps from remotely sensed imagery are used to assign initial hydrophobic layer parameters and thickness. Vegetation regrowth is represented with satellite an Enhanced Vegetation Index. Pre and post-fire hydrologic response is evaluated using runoff measurements at the watershed outlet, and using water component (overland flow, lateral flow, baseflow) measurements.

Assessing Wildlife Habitat And Range Utilization in Arizona Using Satellite Data

NASA Astrophysics Data System (ADS)

Hutchinson, C. F.; Marsh, S. E.; Krausman, P. R.; Enns, R. M.; Howery, L. D.; Trobia, E.; Wallace, C. S.; Walker, J. J.; Mauz, K.; Boyd, H.; Salazar, H.

2001-05-01

Since their reintroduction in 1914, elk (Cervus elaphus) have grown to be a major issue in the western United States. Most land is controlled by federal or state agencies, but individual ranchers have agreements that permit them to graze cattle on much of this land. Elk often compete with cattle for forage, and damage infrastructure (i.e. fences, watering points, and crops). Conversely, environmentalists and hunters also have an interest in the management of elk populations. As a result, consequence of these conflicting interests, there is little agreement about the size of the elk population or the nature, location, and timing of conflicts that elk might cause. This study was intended to provide information that might help managers understand the distribution of elk in Arizona as a consequence of seasonal variation and in response to extreme climatic events (i.e. El Niño and La Niña). The first task involved modeling elk populations over time. There are no long term or large-scale studies of elk movements through continuous observation (i.e. radiocollars). A technique for modeling elk population has been developed that is based on harvest data, gender ratios, and estimates of male mortality. This provided estimates of elk populations for individual game management units (areas for which harvest is reported and within which elk are managed by the Arizona Game and Fish Department). The second task involved the use of satellite data to characterize vegetation responses to seasonal and interannual climate variation among vegetation associations within game management units. This involved the use of NOAA Advanced Very High Resolution Radiometer (AVHRR) time series data to describe temporal vegetation behavior, Landsat and Ikonos data to describe spatial vegetation distribution in conjunction with U.S. Forest Service vegetation maps. Elk population estimates were correlated with satellite-derived vegetation measures by vegetation association through time. The patterns of elk distribution that this revealed were complex. Not surprisingly, animals appear to respond to differences in vegetation availability - both seasonally and interannually - as portrayed by satellite data.

Hydrological drivers of wetland vegetational biodiversity patterns within Everglades National Park, Florida

NASA Astrophysics Data System (ADS)

Todd, J.; Pumo, D.; Azaele, S.; Muneepeerakul, R.; Miralles-Wilhelm, F. R.; Rinaldo, A.; Rodriguez-Iturbe, I.

2009-12-01

The influence of hydrological dynamics on vegetational biodiversity and structuring of wetland environments is of growing interest as wetlands are modified by human alteration and the increasing threat from climate change. Hydrology has long been considered a driving force in shaping wetland communities as the frequency of inundation along with the duration and depth of flooding are key determinants of wetland structure. We attempt to link hydrological dynamics with vegetational distribution and species richness across Everglades National Park (ENP) using two publicly available datasets. The first, the Everglades Depth Estimation Network (EDEN),is a water-surface model which determines the median daily measure of water level across a 400mX400m grid over seven years of measurement. The second is a vegetation map and classification system at the 1:15,000 scale which categorizes vegetation within the Everglades into 79 community types. From these data, we have studied the probabilistic structure of the frequency, duration, and depth of hydroperiods. Preliminary results indicate that the percentage of time a location is inundated is a principal structuring variable with individual communities responding differently. For example, sawgrass appears to be more of a generalist community as it is found across a wide range of time inundated percentages while spike rush has a more restricted distribution and favors wetter environments disproportionately more than predicted at random. Further, the diversity of vegetation communities (e.g. a measure of biodiversity) found across a hydrologic variable does not necessarily match the distribution function for that variable on the landscape. For instance, the number of communities does not differ across the percentage of time inundated. Different measures of vegetation biodiversity such as the local number of community types are also studied at different spatial scales with some characteristics, like the slope of the semi-logarithmic relation between rank and occupancy, found to be robust to scale changes. The ENP offers an expansive natural environment in which to study how vegetational dynamics and community composition are affected by hydrologic variables from the small scale (at the individual community level) to the large (biodiversity measures at differing spatial scales).

Urban area thermal monitoring: Liepaja case study using satellite and aerial thermal data

NASA Astrophysics Data System (ADS)

Gulbe, Linda; Caune, Vairis; Korats, Gundars

2017-12-01

The aim of this study is to explore large (60 m/pixel) and small scale (individual building level) temperature distribution patterns from thermal remote sensing data and to conclude what kind of information could be extracted from thermal remote sensing on regular basis. Landsat program provides frequent large scale thermal images useful for analysis of city temperature patterns. During the study correlation between temperature patterns and vegetation content based on NDVI and building coverage based on OpenStreetMap data was studied. Landsat based temperature patterns were independent from the season, negatively correlated with vegetation content and positively correlated with building coverage. Small scale analysis included spatial and raster descriptor analysis for polygons corresponding to roofs of individual buildings for evaluating insulation of roofs. Remote sensing and spatial descriptors are poorly related to heat consumption data, however, thermal aerial data median and entropy can help to identify poorly insulated roofs. Automated quantitative roof analysis has high potential for acquiring city wide information about roof insulation, but quality is limited by reference data quality and information on building types, and roof materials would be crucial for further studies.

The social distribution of dietary patterns. Traditional, modern and healthy eating among women in a Latin American city.

PubMed

Bojorquez, Ietza; Unikel, Claudia; Cortez, Irene; Cerecero, Diego

2015-09-01

Popkin's nutrition transition model proposes that after the change from the traditional to the modern dietary pattern, another change toward "healthy eating" could occur. As health-related practices are associated with social position, with higher socioeconomic groups generally being the first to adopt public health recommendations, a gradient of traditional-modern-healthy dietary patterns should be observed between groups. The objectives of this article were: 1) to describe the dietary patterns of a representative sample of adult women; 2) to assess whether dietary patterns differentiate in traditional, modern and healthy; and 3) to evaluate the association of social position and dietary patterns. We conducted a survey in Tijuana, a Mexican city at the Mexico-United States (US) border. Women 18-65 years old (n = 2345) responded to a food frequency questionnaire, and questions about socioeconomic and demographic factors. We extracted dietary patterns through factor analysis, and employed indicators of economic and cultural capital, life course stage and migration to define social position. We evaluated the association of social position and dietary patterns with linear regression models. Three patterns were identified: "tortillas," "hamburgers" and "vegetables." Women in a middle position of economic and cultural capital scored higher in the "hamburgers" pattern, and women in upper positions scored higher in the "vegetables" pattern. Economic and cultural capitals and migration interacted, so that for women lower in economic capital, having lived in the US was associated with higher scores in the "hamburgers" pattern. Copyright © 2015 Elsevier Ltd. All rights reserved.

Animal-vegetal polarity in the plasma membrane of a molluscan egg: a quantitative freeze-fracture study.

PubMed

Speksnijder, J E; Mulder, M M; Dohmen, M R; Hage, W J; Bluemink, J G

1985-03-01

Using freeze-fracture electron microscopy, the numerical particle distribution in the fertilized Nassarius egg plasma membrane has been analyzed in four areas at different positions along the animal-vegetal axis of the egg. These areas can be distinguished by distinct microvilli patterns and differences in microvilli densities. In all areas, more IMPs (intramembrane particles) are present on the P face than on the corresponding E face. The ratio of the number of IMPs present on E and P face is similar in all areas (0.48-0.55) except for the most animal part of the vegetal hemisphere, where relatively more IMPs remain attached to the exterior half of the fractured membrane (E/P ratio = 0.88). The IMP density at the vegetal pole of the egg is considerably higher than in the animal hemisphere and in the animal part of the vegetal hemisphere. This difference is due to an increased number of IMPs in all size classes (4-18 nm). In the area adjacent to the vegetal pole the density of particles is also higher than in the two more animal areas, but here the difference is exclusively due to the smaller IMP size classes (4-8 nm). Statistical analysis of our data reveals that the area adjacent to the vegetal pole patch is significantly different from the other areas with respect to the distribution of the IMPs over the different IMP size classes. These results demonstrate the polar organization of the Nassarius egg plasma membrane. The possible role of this surface heterogeneity in the spatial organization of the egg cell and the later embryo is discussed.

Linking boundary-layer circulations and surface processes during FIFE89. Part 1: Observational analysis

NASA Technical Reports Server (NTRS)

Smith, Eric A.; Wai, Mickey M.-K.; Cooper, Harry J.; Rubes, Michael T.; Hsu, Ann

1994-01-01

Surface, aircraft, and satellite observations are analyzed for the 21-day 1989 intensive field campaign of the First ISLSCP Field Experiment (FIFE) to determine the effect of precipitation, vegetation, and soil moisture distributions on the thermal properties of the surface including the heat and moisture fluxes, and the corresponding response in the boundary-layer circulation. Mean and variance properties of the surface variables are first documented at various time and space scales. These calculations are designed to set the stage for Part 2, a modeling study that will focus on how time-space dependent rainfall distribution influences the intensity of the feedback between a vegetated surface and the atmospheric boundary layer. Further analysis shows strongly demarked vegetation and soil moisture gradients extending across the FIFE experimental site that were developed and maintained by the antecedent and ongoing spatial distribution of rainfall over the region. These gradients are shown to have a pronounced influence on the thermodynamic properties of the surface. Furthermore, perturbation surface wind analysis suggests for both short-term steady-state conditions and long-term averaged conditions that the gradient pattern maintained a diurnally oscillating local direct circulation with perturbation vertical velocities of the same order as developing cumulus clouds. Dynamical and scaling considerations suggest that the embedded perturbation circulation is driven by surface heating/cooling gradients and terrain ef fects rather than the manifestation of an inertial oscillation. The implication is that at even relatively small scales (less than 30 km), the differential evolution in vegetation density and soil moisture distribution over a relatively homogenous ecotone can give rise to preferential boundary-layer circulations capable of modifying local-scale horizontal and vertical motions.

North American vegetation patterns observed with the NOAA-7 advanced very high resolution radiometer. [North America

NASA Technical Reports Server (NTRS)

Goward, S. N.; Tucker, C. J.; Dye, D. G.

1985-01-01

Spectral vegetation index measurements derived from remotely sensed observations show great promise as a means to improve knowledge of land vegetation patterns. The daily, global observations acquired by the advanced very high resolution radiometer, a sensor on the current series of U.S. National Oceanic and Atmospheric Administration meteorological satellites, may be particularly well suited for global studies of vegetation. Preliminary results from analysis of North American observations, extending from April to November 1982, show that the vegetation index patterns observed correspond to the known seasonality of North American natural and cultivated vegetation. Integration of the observations over the growing season produced measurements that are related to net primary productivity patterns of the major North American natural vegetation formations. Regions of intense cultivation were observed as anomalous areas in the integrated growing season measurements. Significant information on seasonality, annual extent and interannual variability of vegetation photosynthetic activity at continental and global scales can be derived from these satellite observations.

The use of Skylab data to study the early detection of insect infestations and density and distribution of host plants

NASA Technical Reports Server (NTRS)

Hart, W. G.; Ingle, S. J.; Davis, M. R.

1975-01-01

The detection of insect infestations and the density and distribution of host plants were studied using Skylab data, aerial photography and ground truth simultaneously. Additional ground truth and aerial photography were acquired between Skylab passes. Three test areas were selected: area 1, of high density citrus, was located northwest of Mission, Texas; area 2, 20 miles north of Weslaco, Texas, irrigated pastures and brush-covered land; area 3 covered the entire Lower Rio Grande Valley and adjacent areas of Mexico. A color composite picture of S-190A data showed patterns of vegetation on both sides of the Rio Grande River clearly delineating the possible avenues of entry of pest insects from Mexico into the United States or from the United States into Mexico. Vegetation that could be identified with conventional color and color IR film included: citrus, brush, sugarcane, alfalfa, irrigated and unimproved pastures.

In the Shade of Affluence: The Inequitable Distribution of the Urban Heat Island

NASA Technical Reports Server (NTRS)

Harlan, Sharon L.; Brazel, Anthony J.; Jenerette, G. Darrel; Jones, Nancy S.; Larsen, Larissa; Prashad, Lela

2008-01-01

The urban heat island is an unintended consequence of humans building upon rural and native landscapes. We hypothesized that variations in vegetation and land use patterns across an urbanizing regional landscape would produce a temperature distribution that was spatially heterogeneous and correlated with the social characteristics of urban neighborhoods. Using biophysical and social data scaled to conform to US census geography, we found that affluent whites were more likely to live in vegetated and less climatically stressed neighborhoods likely to live in than low-income Latinos in Phoenix, Arizona. Affluent neighborhoods had cooler summer temperatures that reduced exposure to outdoor heat-related health risks, especially during a heat wave period. In addition to being warmer, poorer neighborhoods lacked critical resources in their physical and social environments to help them cope with extreme heat. Increased average temperatures due to climate change are expected to exacerbate the impacts of urban heat islands.

Observations of soil moisture and infiltrability in contour-aligned, banded chenopod shrubland at Fowlers Gap, arid western NSW, Australia.

NASA Astrophysics Data System (ADS)

Dunkerley, D.

2009-04-01

Speculation abounds concerning the drivers of spatial patterning in dryland vegetation, and many numerical analyses have been built with little use of field evidence for parameterisation or validation. In fact, studies of soil moisture distribution, the most commonly hypothesised driver of pattern formation, are uncommon. Here, soil infiltrability and soil moisture data are presented from a banded vegetation community in arid western NSW Australia. The site had received 40 mm of rain in one day a week prior to field measurement. This is an exceptional rain event for this region, and provided the opportunity to observe resulting distributions of soil moisture within various mosaics, including contour-aligned groves and intergroves in chenopod shrubland. Results taken at 2 m intervals across many cycles of the repeating banded pattern show that near-surface (6 cm) soil moisture is relatively constant, except in lower intergroves, which were drier. Patterns of soil infiltrability by cylinder infiltrometer follow the same pattern, with lowest values at the same locations as the soil moisture minima. Locally high soil infiltrabilities occur in both grove and intergrove, but low values are restricted to intergroves. These results suggest that any runoff-runon system operating at the site is driven largely from the intergroves, where high bulk density, hydrophobic biological soil crusts, and mantles of small stones with associated vesicular horizons, limit water entry. If this is so, it suggests that attention must be paid to intergrove processes, which may be more significant that plant facilitation within groves. Model developments will thus need to address the evolution of low infiltrability in intergroves in parallel with any high infiltrability within groves.

UNMANNED AERIAL VEHICLE (UAV) HYPERSPECTRAL REMOTE SENSING FOR DRYLAND VEGETATION MONITORING

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nancy F. Glenn; Jessica J. Mitchell; Matthew O. Anderson

2012-06-01

UAV-based hyperspectral remote sensing capabilities developed by the Idaho National Lab and Idaho State University, Boise Center Aerospace Lab, were recently tested via demonstration flights that explored the influence of altitude on geometric error, image mosaicking, and dryland vegetation classification. The test flights successfully acquired usable flightline data capable of supporting classifiable composite images. Unsupervised classification results support vegetation management objectives that rely on mapping shrub cover and distribution patterns. Overall, supervised classifications performed poorly despite spectral separability in the image-derived endmember pixels. Future mapping efforts that leverage ground reference data, ultra-high spatial resolution photos and time series analysis shouldmore » be able to effectively distinguish native grasses such as Sandberg bluegrass (Poa secunda), from invasives such as burr buttercup (Ranunculus testiculatus) and cheatgrass (Bromus tectorum).« less

Carbon Inputs From Riparian Vegetation Limit Oxidation of Physically Bound Organic Carbon Via Biochemical and Thermodynamic Processes: OC Oxidation Processes Across Vegetation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Graham, Emily B.; Tfaily, Malak M.; Crump, Alex R.

In light of increasing terrestrial carbon (C) transport across aquatic boundaries, the mechanisms governing organic carbon (OC) oxidation along terrestrial-aquatic interfaces are crucial to future climate predictions. Here, we investigate biochemistry, metabolic pathways, and thermodynamics corresponding to OC oxidation in the Columbia River corridor. We leverage natural vegetative differences to encompass variation in terrestrial C inputs. Our results suggest that decreases in terrestrial C deposition associated with diminished riparian vegetation induce oxidation of physically-bound (i.e., mineral and microbial) OC at terrestrial-aquatic interfaces. We also find that contrasting metabolic pathways oxidize OC in the presence and absence of vegetation and—in directmore » conflict with the concept of ‘priming’—that inputs of water-soluble and thermodynamically-favorable terrestrial OC protects bound-OC from oxidation. Based on our results, we propose a mechanistic conceptualization of OC oxidation along terrestrial-aquatic interfaces that can be used to model heterogeneous patterns of OC loss under changing land cover distributions.« less

Metabolism of Mevalonic Acid in Vegetative and Induced Plants of Xanthium strumarium.

PubMed

Bledsoe, C S

1978-11-01

The metabolism of mevalonic acid in Xanthium strumarium L. Chicago plants was studied to determine how mevalonate was metabolized and whether metabolism was related to induction of flowering. Leaves of vegetative, photoperiodically induced, and chemically inhibited cocklebur plants were supplied with [(14)C]mevalonic acid prior to or during a 16-hour inductive dark period. Vegetative, induced, and Tris(2-diethylaminoethyl)phosphate trihydrochloride-treated plants did not differ significantly in the amount of [(14)C]mevalonic acid they absorbed, nor in the distribution of radioactivity among the leaf blade (97%), petiole (2.3%), or shoot tip (0.7%). [(14)C]Mevalonic acid was rapidly metabolized and transported out of the leaves. Possible metabolites of mevalonate were mevalonic acid phosphates and sterols. No detectable (14)C was found in gibberellins, carotenoids, or the phytol alcohol of chlorophyll. Chemically inhibited plants accumulated (14)C compounds not found in vegetative or induced plants. When ethanol extracts of leaves, petioles, and buds were chromatographed, comparisons of chromatographic patterns did not show significant differences between vegetative and induced treatments.

Metabolism of Mevalonic Acid in Vegetative and Induced Plants of Xanthium strumarium 1

PubMed Central

Bledsoe, Caroline S.; Ross, Cleon W.

1978-01-01

The metabolism of mevalonic acid in Xanthium strumarium L. Chicago plants was studied to determine how mevalonate was metabolized and whether metabolism was related to induction of flowering. Leaves of vegetative, photoperiodically induced, and chemically inhibited cocklebur plants were supplied with [14C]mevalonic acid prior to or during a 16-hour inductive dark period. Vegetative, induced, and Tris(2-diethylaminoethyl)phosphate trihydrochloride-treated plants did not differ significantly in the amount of [14C]mevalonic acid they absorbed, nor in the distribution of radioactivity among the leaf blade (97%), petiole (2.3%), or shoot tip (0.7%). [14C]Mevalonic acid was rapidly metabolized and transported out of the leaves. Possible metabolites of mevalonate were mevalonic acid phosphates and sterols. No detectable 14C was found in gibberellins, carotenoids, or the phytol alcohol of chlorophyll. Chemically inhibited plants accumulated 14C compounds not found in vegetative or induced plants. When ethanol extracts of leaves, petioles, and buds were chromatographed, comparisons of chromatographic patterns did not show significant differences between vegetative and induced treatments. ImagesFig. 1 PMID:16660583

Probing the Gaps: A Synthesis of Well-known and Lesser-known Hydrological Feedbacks Influencing Vegetation Patterning and Long-term Geomorphic Change in Low-gradient Fluvial Landscapes

NASA Astrophysics Data System (ADS)

Larsen, L.; Christensen, A.; Harvey, J. W.; Ma, H.; Newman, S.; Saunders, C.; Twilley, R.

2017-12-01

Emergence of vegetation patterning in fluvial landscapes is a classic example of how autogenic processes can drive long term fluvial and geomorphic adjustments in aquatic ecosystems. Studies elucidating the physics of flow through vegetation patches have produced understanding of how patterning in topography and vegetation commonly emerges and what effect it has on long term geomorphic change. However, with regard to mechanisms underlying pattern existence and resilience, several knowledge gaps remain, including the role of landscape-scale flow-vegetation feedbacks, feedbacks that invoke additional biogeochemical or biological agents, and determination of the relative importance of autogenic processes relative to external drivers. Here we provide a synthesis of the processes over a range of scales known to drive vegetation patterning and sedimentation in low gradient fluvial landscapes, emphasizing recent field and modeling studies in the Everglades, FL and Wax Lake Delta, LA that address these gaps. In the Everglades, while flow routing and sediment redistribution at the patch scale is known to be a primary driver of vegetation pattern emergence, landscape-scale routing of flow, as driven by the landscape's connectivity, can set up positive feedbacks that influence the rate of pattern degradation. Recent flow release experiments reveal that an additional feedback, involving phosphorus concentrations, flow, and floating vegetation communities that are abundant under low phosphorus, low flow conditions further stabilizes the alternative landscape states established through local scale sediment redistribution. Biogeochemistry-vegetation-sediment feedbacks may also be important for geomorphic development of newly emerging landscapes such as the Wax Lake Delta. There, fine sediment deposition shapes hydrogeomorphic zones with vegetation patterns that stimulate the growth of biofilm, while biofilm characteristics override the physical characteristics of vegetation canopies in determining fine sediment deposition rates and influence nitrogen and carbon biogeochemistry. Emerging tools and data streams, such as information flow analysis of lidar-derived vegetation biovolume and topography, can help identify the relative roles of autogenic vs. external forcing in these landscapes.

Climate-driven C4 plant distributions in China: divergence in C4 taxa

PubMed Central

Wang, Renzhong; Ma, Linna

2016-01-01

There have been debates on the driving factors of C4 plant expansion, such as PCO2 decline in the late Micocene and warmer climate and precipitation at large-scale modern ecosystems. These disputes are mainly due to the lack of direct evidence and extensive data analysis. Here we use mass flora data to explore the driving factors of C4 distribution and divergent patterns for different C4 taxa at continental scale in China. The results display that it is mean annual climate variables driving C4 distribution at present-day vegetation. Mean annual temperature is the critical restriction of total C4 plants and the precipitation gradients seem to have much less impact. Grass and sedge C4 plants are largely restricted to mean annual temperature and precipitation respectively, while Chenopod C4 plants are strongly restricted by aridity in China. Separate regression analysis can succeed to detect divergences of climate distribution patterns of C4 taxa at global scale. PMID:27302686

Association between mapped vegetation and Quaternary geology on Santa Rosa Island, California

NASA Astrophysics Data System (ADS)

Cronkite-Ratcliff, C.; Corbett, S.; Schmidt, K. M.

2017-12-01

Vegetation and surficial geology are closely connected through the interface generally referred to as the critical zone. Not only do they influence each other, but they also provide clues into the effects of climate, topography, and hydrology on the earth's surface. This presentation describes quantitative analyses of the association between the recently compiled, independently generated vegetation and geologic map units on Santa Rosa Island, part of the Channel Islands National Park in Southern California. Santa Rosa Island was heavily grazed by sheep and cattle ranching for over one hundred years prior to its acquisition by the National Park Service. During this period, the island experienced significant erosion and spatial reduction and diversity of native plant species. Understanding the relationship between geology and vegetation is necessary for monitoring the recovery of native plant species, enhancing the viability of restoration sites, and understanding hydrologic conditions favorable for plant growth. Differences in grain size distribution and soil depth between geologic units support different plant communities through their influence on soil moisture, while differences in unit age reflect different degrees of pedogenic maturity. We find that unsupervised machine learning methods provide more informative insight into vegetation-geology associations than traditional measures such as Cramer's V and Goodman and Kruskal's lambda. Correspondence analysis shows that unique vegetation-geology patterns associated with beach/dune, grassland, hillslope/colluvial, and fluvial/wetland environments can be discerned from the data. By combining geology and vegetation with topographic variables, mixture models can be used to partition the landscape into multiple representative types, which then be compared with conceptual models of plant growth and succession over different landforms. Using this collection of methods, we show various ways that that Quaternary geology provides valuable information on the distribution of vegetation species in recovering ecosystems. Going forward, these analyses provide insights on favorable areas for natural and managed recovery of native vegetation species as well as criteria for future field sampling and monitoring.

Determination of optimum viewing angles for the angular normalization of land surface temperature over vegetated surface.

PubMed

Ren, Huazhong; Yan, Guangjian; Liu, Rongyuan; Li, Zhao-Liang; Qin, Qiming; Nerry, Françoise; Liu, Qiang

2015-03-27

Multi-angular observation of land surface thermal radiation is considered to be a promising method of performing the angular normalization of land surface temperature (LST) retrieved from remote sensing data. This paper focuses on an investigation of the minimum requirements of viewing angles to perform such normalizations on LST. The normally kernel-driven bi-directional reflectance distribution function (BRDF) is first extended to the thermal infrared (TIR) domain as TIR-BRDF model, and its uncertainty is shown to be less than 0.3 K when used to fit the hemispheric directional thermal radiation. A local optimum three-angle combination is found and verified using the TIR-BRDF model based on two patterns: the single-point pattern and the linear-array pattern. The TIR-BRDF is applied to an airborne multi-angular dataset to retrieve LST at nadir (Te-nadir) from different viewing directions, and the results show that this model can obtain reliable Te-nadir from 3 to 4 directional observations with large angle intervals, thus corresponding to large temperature angular variations. The Te-nadir is generally larger than temperature of the slant direction, with a difference of approximately 0.5~2.0 K for vegetated pixels and up to several Kelvins for non-vegetated pixels. The findings of this paper will facilitate the future development of multi-angular thermal infrared sensors.

Determination of Optimum Viewing Angles for the Angular Normalization of Land Surface Temperature over Vegetated Surface

PubMed Central

Ren, Huazhong; Yan, Guangjian; Liu, Rongyuan; Li, Zhao-Liang; Qin, Qiming; Nerry, Françoise; Liu, Qiang

2015-01-01

Multi-angular observation of land surface thermal radiation is considered to be a promising method of performing the angular normalization of land surface temperature (LST) retrieved from remote sensing data. This paper focuses on an investigation of the minimum requirements of viewing angles to perform such normalizations on LST. The normally kernel-driven bi-directional reflectance distribution function (BRDF) is first extended to the thermal infrared (TIR) domain as TIR-BRDF model, and its uncertainty is shown to be less than 0.3 K when used to fit the hemispheric directional thermal radiation. A local optimum three-angle combination is found and verified using the TIR-BRDF model based on two patterns: the single-point pattern and the linear-array pattern. The TIR-BRDF is applied to an airborne multi-angular dataset to retrieve LST at nadir (Te-nadir) from different viewing directions, and the results show that this model can obtain reliable Te-nadir from 3 to 4 directional observations with large angle intervals, thus corresponding to large temperature angular variations. The Te-nadir is generally larger than temperature of the slant direction, with a difference of approximately 0.5~2.0 K for vegetated pixels and up to several Kelvins for non-vegetated pixels. The findings of this paper will facilitate the future development of multi-angular thermal infrared sensors. PMID:25825975

Natural resource inventories and management applications in the Great Basin. [Nevada vegetation and wildlands

NASA Technical Reports Server (NTRS)

Tueller, P. T.; Lorain, G.; Halvorson, R. M.

1974-01-01

ERTS-1 resolution capabilities and repetitive coverage have allowed the acquisition of several statewide inventories of natural resource features not previously completed or that could not be completed in any other way. Familiarity with landform, tone, pattern and other converging factors, along with multidate imagery, has been required. Nevada's vegetation has been mapped from ERTS-1. Dynamic characteristics of the landscape have been studied. Sequential ERTS-1 imagery has proved its usefulness for mapping vegetation, following vegetation phenology changes, monitoring changes in lakes and reservoirs (including water quality), determining changes in surface mining use, making fire fuel estimates and determining potential hazard, mapping the distribution of rain and snow events, making range readiness determinations, monitoring marshland management practices and other uses. Feasibility has been determined, but details of incorporating the data in management systems awaits further research and development. The need is to accurately define the steps necessary to extract required or usable information from ERTS imagery and fit it into on-going management programs.

Effect of long term organic amendments and vegetation of vineyard soils on the microscale distribution and biogeochemistry of copper.

PubMed

Navel, Aline; Martins, Jean M F

2014-01-01

In this study we evaluated the effect of the long term organic management of a vineyard-soil on the biogeochemistry of copper at the micro-aggregate scale. The model vineyard-soil (Mâcon-France) experienced a long-term field-experiment that consisted in amendments and vegetations with various materials and plants. We studied specifically the effect of Straw (S) and Conifer Compost (CC) organic amendments and Clover (Cl) and Fescue (F) vegetation on the fate of copper (fungicide) in the surface layer of this loamy soil, through a comparison with the Non Amended soil (NA). After collection the five soils were immediately physically fractionated in order to obtain 5 granulometric size-fractions. All soils and size-fractions were quantitatively characterized in terms of granulometry, chemical content and copper distribution, speciation and bioavailability to bacteria and plants. The results showed strong increases of soil-constituents aggregation for all treatments (Cl>CC>S>F>NA), in relation with the increased cementation of soil-constituents by organic matter (OM). The distribution patterns of all major elements and organic carbon were found highly variable within the soil sub-fractions and also between the 5 treatments. Due to their specific inorganic and organic composition, soil sub-fractions can thus be considered as a specific microbial habitat. Added OM accumulated preferentially in the 20-2 μm and in the >250 μm of the 5 soils. The distribution patterns of copper as well as its speciation and bioavailability to bacteria in the soil sub-fractions were shown to be strongly different among the five soils, in relation with OM distribution. Our results also suggest that Cu-bioavailability to plants is controlled by soil-rhizosphere structure. Altogether our results permitted to show that long-term organic management of a vineyard soil induced stable modifications of soil physical and chemical properties at both macro and micro-scales. These modifications affected in turn the micro-scale biogeochemistry of copper, and especially its bioavailability to bacteria and plants. © 2013.

Vegetation Variability And Its Effect On Monsoon Rainfall Over South East Asia: Observational and Modeling Results

NASA Astrophysics Data System (ADS)

Sarkar, S.; Peters-Lidard, C.; Chiu, L.; Kafatos, M.

2005-12-01

Increasing population and urbanization have created stress on developing nations. The quickly shifting patterns of vegetation change in different parts of the world have given rise to the pertinent question of feedback on the climate prevailing on local to regional scales. It is now known with some certainty, that vegetation changes can affect the climate by influencing the heat and water balance. The hydrological cycle particularly is susceptible to changes in vegetation. The Monsoon rainfall forms a vital link in the hydrological cycle prevailing over South East Asia This work examines the variability of vegetation over South East Asia and assesses its impact on the monsoon rainfall. We explain the role of changing vegetation and show how this change has affected the heat and energy balance. We demonstrate the role of vegetation one season earlier in influencing rainfall intensity over specific areas in South East Asia and show the ramification of vegetation change on the summer rainfall behavior. The vegetation variability study specifically focuses on India and China, two of the largest and most populous nations. We have done an assessment to find out the key meteorological and human induced parameters affecting vegetation over the study area through a spatial analysis of monthly NDVI values. This study highlights the role of monsoon rainfall, regional climate dynamics and large scale human induced pollution to be the crucial factors governing the vegetation and vegetation distribution. The vegetation is seen to follow distinct spatial patterns that have been found to be crucial in its eventual impact on monsoon rainfall. We have carried out a series of sensitivity experiments using a land surface hydrologic modeling scheme. The vital energy and water balance parameters are identified and the daily climatological cycles are examined for possible change in behavior for different boundary conditions. It is found that the change from native deciduous forest vegetation to crop land affects monsoon rainfall in two ways: 1) The presence of cropland increases the sensible heat release from ground, increasing the chances for development of forced convection; 2) Large scale irrigation associated with spring crop development creates a moister lower boundary layer thus inducing more moist instability and free convection in the succeeding season.

A study to explore the use of orbital remote sensing to determine native arid plant distribution. [Arizona

NASA Technical Reports Server (NTRS)

Mcginnies, W. G.; Haase, E. F. (Principal Investigator); Musick, H. B. (Compiler)

1973-01-01

The author has identified the following significant results. Ground truth spectral signature data for various types of scenes, including ground with and without annuals, and various shrubs, were collected. When these signature data are plotted with infrared (MSS band 6 or 7) reflectivity on one axis and red (MSS band 5) reflectivity on the other axis, clusters of data from the various types of scenes are distinct. This method of expressing spectral signature data appears to be more useful for distinguishing types of scenes than a simple infrared to red reflectivity ration. Large areas of varnished desert pavement are visible and mappable on ERTS-1 and high altitude aircraft imagery. A large scale vegetation pattern was found to be correlated with the presence of the desert pavement. The large scale correlation was used in mapping the vegetation of the area. It was found that a distinctive soil type was associated with the presence of the varnished desert pavement. The high salinity and exchangeable sodium percentage of this soil type provide a basis for the explanation of both the large scale and small scale vegetation pattern.

Tundra landform and vegetation productivity trend maps for the Arctic Coastal Plain of northern Alaska

PubMed Central

Lara, Mark J.; Nitze, Ingmar; Grosse, Guido; McGuire, A. David

2018-01-01

Arctic tundra landscapes are composed of a complex mosaic of patterned ground features, varying in soil moisture, vegetation composition, and surface hydrology over small spatial scales (10–100 m). The importance of microtopography and associated geomorphic landforms in influencing ecosystem structure and function is well founded, however, spatial data products describing local to regional scale distribution of patterned ground or polygonal tundra geomorphology are largely unavailable. Thus, our understanding of local impacts on regional scale processes (e.g., carbon dynamics) may be limited. We produced two key spatiotemporal datasets spanning the Arctic Coastal Plain of northern Alaska (~60,000 km2) to evaluate climate-geomorphological controls on arctic tundra productivity change, using (1) a novel 30 m classification of polygonal tundra geomorphology and (2) decadal-trends in surface greenness using the Landsat archive (1999–2014). These datasets can be easily integrated and adapted in an array of local to regional applications such as (1) upscaling plot-level measurements (e.g., carbon/energy fluxes), (2) mapping of soils, vegetation, or permafrost, and/or (3) initializing ecosystem biogeochemistry, hydrology, and/or habitat modeling. PMID:29633984

Tundra landform and vegetation productivity trend maps for the Arctic Coastal Plain of northern Alaska

USGS Publications Warehouse

Lara, Mark J.; Nitze, Ingmar; Grosse, Guido; McGuire, A. David

2018-01-01

Arctic tundra landscapes are composed of a complex mosaic of patterned ground features, varying in soil moisture, vegetation composition, and surface hydrology over small spatial scales (10–100 m). The importance of microtopography and associated geomorphic landforms in influencing ecosystem structure and function is well founded, however, spatial data products describing local to regional scale distribution of patterned ground or polygonal tundra geomorphology are largely unavailable. Thus, our understanding of local impacts on regional scale processes (e.g., carbon dynamics) may be limited. We produced two key spatiotemporal datasets spanning the Arctic Coastal Plain of northern Alaska (~60,000 km2) to evaluate climate-geomorphological controls on arctic tundra productivity change, using (1) a novel 30 m classification of polygonal tundra geomorphology and (2) decadal-trends in surface greenness using the Landsat archive (1999–2014). These datasets can be easily integrated and adapted in an array of local to regional applications such as (1) upscaling plot-level measurements (e.g., carbon/energy fluxes), (2) mapping of soils, vegetation, or permafrost, and/or (3) initializing ecosystem biogeochemistry, hydrology, and/or habitat modeling.

Vegetation pattern formation in a fog-dependent ecosystem.

PubMed

Borthagaray, Ana I; Fuentes, Miguel A; Marquet, Pablo A

2010-07-07

Vegetation pattern formation is a striking characteristic of several water-limited ecosystems around the world. Typically, they have been described on runoff-based ecosystems emphasizing local interactions between water, biomass interception, growth and dispersal. Here, we show that this situation is by no means general, as banded patterns in vegetation can emerge in areas without rainfall and in plants without functional root (the Bromeliad Tillandsia landbeckii) and where fog is the principal source of moisture. We show that a simple model based on the advection of fog-water by wind and its interception by the vegetation can reproduce banded patterns which agree with empirical patterns observed in the Coastal Atacama Desert. Our model predicts how the parameters may affect the conditions to form the banded pattern, showing a transition from a uniform vegetated state, at high water input or terrain slope to a desert state throughout intermediate banded states. Moreover, the model predicts that the pattern wavelength is a decreasing non-linear function of fog-water input and slope, and an increasing function of plant loss and fog-water flow speed. Finally, we show that the vegetation density is increased by the formation of the regular pattern compared to the density expected by the spatially homogeneous model emphasizing the importance of self-organization in arid ecosystems. (c) 2010 Elsevier Ltd. All rights reserved.

The spatial distribution and temporal variation of desert riparian forests and their influencing factors in the downstream Heihe River basin, China

NASA Astrophysics Data System (ADS)

Ding, Jingyi; Zhao, Wenwu; Daryanto, Stefani; Wang, Lixin; Fan, Hao; Feng, Qiang; Wang, Yaping

2017-05-01

Desert riparian forests are the main restored vegetation community in Heihe River basin. They provide critical habitats and a variety of ecosystem services in this arid environment. Since desert riparian forests are also sensitive to disturbance, examining the spatial distribution and temporal variation of these forests and their influencing factors is important to determine the limiting factors of vegetation recovery after long-term restoration. In this study, field experiment and remote sensing data were used to determine the spatial distribution and temporal variation of desert riparian forests and their relationship with the environmental factors. We classified five types of vegetation communities at different distances from the river channel. Community coverage and diversity formed a bimodal pattern, peaking at the distances of 1000 and 3000 m from the river channel. In general, the temporal normalized difference vegetation index (NDVI) trend from 2000 to 2014 was positive at different distances from the river channel, except for the region closest to the river bank (i.e. within 500 m from the river channel), which had been undergoing degradation since 2011. The spatial distribution of desert riparian forests was mainly influenced by the spatial heterogeneity of soil properties (e.g. soil moisture, bulk density and soil particle composition). Meanwhile, while the temporal variation of vegetation was affected by both the spatial heterogeneity of soil properties (e.g. soil moisture and soil particle composition) and to a lesser extent, the temporal variation of water availability (e.g. annual average and variability of groundwater, soil moisture and runoff). Since surface (0-30 cm) and deep (100-200 cm) soil moisture, bulk density and the annual average of soil moisture at 100 cm obtained from the remote sensing data were regarded as major determining factors of community distribution and temporal variation, conservation measures that protect the soil structure and prevent soil moisture depletion (e.g. artificial soil cover and water conveyance channels) were suggested to better protect desert riparian forests under climate change and intensive human disturbance.

[Distribution patterns and pollution assessments of heavy metals in the Spartina alterniflora salt-marsh wetland of Rudong, Jiangsu province].

PubMed

Zhang, Long-Hui; Du, Yong-Fen; Wang, Dan-Dan; Gao, Shu; Gao, Wen-Hua

2014-06-01

To understand the ecological impact of Spartina alterniflora on the coastal wetland environment, field survey was carried out in July, 2010, over the intertidal areas of Rudong coast, Jiangsu province; sediment samples were collected from a series of stations with different conditions of vegetation cover and S. alterniflora growth. The contents of eight heavy metals, together with sediment composition and total organic carbon were analyzed to reveal the distribution patterns of the heavy metals. Environmental quality status was evaluated using both the index of geoaccumulation (I(geo)) and the index of the Håkanson ecological risk. The analytical results showed that the average contents of Pb, Cd, As, Hg, Cr, Cu, Ni and Zn were below the standard for the Category I sediment quality, among which Cd, Hg, Ni and Zn exceeded the sediment background value of the region. On the whole, the contents of eight heavy metals in vegetation areas were higher than those associated with the adjacent bare flat areas. These data sets indicate a non-polluted condition in term of I(geo) estimation; however, a critical state of low to moderate degrees of pollution and a low level of risk were deduced according to the index of the Håkanson potential ecological risk. Both indices suggested that the pollution level of Hg and Cd were the highest among the eight metals measured. Along the transection from seaward to landward, the contents of As, Cu and Hg, their indices of I(geo) and Håkanson ecological risk all showed an increasing tread, in accordance with the condition of vegetation cover. Along the coastline with S. alterniflora being distributed in patchiness, all metal contents and their ecological risk level values for the marshes were higher than those for the unvegetated sediments nearby; moreover, except for Hg, other seven metals exhibited relatively low values than those in the shore-normal section with a better S. alterniflora growth. These findings indicate that S. alterniflora is one of important factors to enrich the heavy metal in tidal flat sediment. Thus, ecological risk of the heavy metal is reduced or blocked, due to the filtering effect of salt-marsh, which prevents metals from entering the open sea directly. The distribution of heavy metal is influenced by a combination of colonization time of vegetation, chemical form of metals and their origins.

Patterns of ecology and distribution of the tree crickets Oecanthus dulcisonans and O. pellucens (Orthoptera: Gryllidae; Oecanthinae) in southern Italy.

PubMed

Labadessa, Rocco; Todisco, Simone

2016-09-21

Ecological proclivities of the tree cricket Oecanthus dulcisonans, which has been recently separated from the well known O. pellucens, have been poorly investigated. Moreover, studies on the patterns driving niche segregation between these related species are still needed. This study aims to explore the role of macro-habitat in shaping the distribution of O. dulcisonans and O. pellucens in southern Italy. Occurrence data were sampled by means of a rapid acoustic survey scheme at a regional scale. The significance of difference in ecological and habitat parameters was tested between the two species. While confirming species behavioural patterns, new findings are provided with regard to their ecological difference. Species distribution proves to be primarily driven by elevation gradient and temperature variation, with O. dulcisonans common and widespread in warmer lowlands and O. pellucens limited to higher altitudes. The two species also show significant spatial segregation within vegetation layers. These findings also provide cues for future studies on species interaction, as well as for the assessment of a monitoring scheme which may help interpreting the effects of broad environmental changes.

Vegetation mapping from high-resolution satellite images in the heterogeneous arid environments of Socotra Island (Yemen)

NASA Astrophysics Data System (ADS)

Malatesta, Luca; Attorre, Fabio; Altobelli, Alfredo; Adeeb, Ahmed; De Sanctis, Michele; Taleb, Nadim M.; Scholte, Paul T.; Vitale, Marcello

2013-01-01

Socotra Island (Yemen), a global biodiversity hotspot, is characterized by high geomorphological and biological diversity. In this study, we present a high-resolution vegetation map of the island based on combining vegetation analysis and classification with remote sensing. Two different image classification approaches were tested to assess the most accurate one in mapping the vegetation mosaic of Socotra. Spectral signatures of the vegetation classes were obtained through a Gaussian mixture distribution model, and a sequential maximum a posteriori (SMAP) classification was applied to account for the heterogeneity and the complex spatial pattern of the arid vegetation. This approach was compared to the traditional maximum likelihood (ML) classification. Satellite data were represented by a RapidEye image with 5 m pixel resolution and five spectral bands. Classified vegetation relevés were used to obtain the training and evaluation sets for the main plant communities. Postclassification sorting was performed to adjust the classification through various rule-based operations. Twenty-eight classes were mapped, and SMAP, with an accuracy of 87%, proved to be more effective than ML (accuracy: 66%). The resulting map will represent an important instrument for the elaboration of conservation strategies and the sustainable use of natural resources in the island.

Past and present vegetation ecology of Laetoli, Tanzania.

PubMed

Andrews, Peter; Bamford, Marion

2008-01-01

We are attempting to set up a new protocol for palaeoecological reconstruction in relation to the fossil hominin site Laetoli, Tanzania. This is based on the premise that habitat variability in the past was at least as great as at present; that this variability at the landscape level is a function of variations in geology, soils, and topography rather than climate; and that vegetation type at the landscape level can be reconstructed from these environmental variables. Measurable variation in climate in tropical Africa today occurs over distances of at least 100 km, so that ranges of habitat variation within the limited area of Laetoli today can be reconstructed in relation to soils and topography, and the effects of climate changes are then estimated in relation to these other factors. In order to document the modern vegetation, we have made voucher collections of plants in the Laetoli region, recorded distributions of plants by habitat, climate, soil, and topography, and mapped the vegetation distributions. Results show that areas of low relief have soils with impeded drainage and dense Acacia drepanolobium woodland, having low canopies when disturbed by human action, higher when not; shallow brown soils on volcanic lavas have four woodland associations, two dominated by Acacia species, two by Combretum-Albizia species; shallow volcanic soils to the east have a woodland association with Croton-Dombeya-Albizia species; elevated land to the east on volcanic soils has two associations of montane-edge species, one with Croton-Celtis-Lepidotrichilia, and the other with Acacia lahai; the eastern highlands above 2,750 m have montane forest; seasonal water channels flowing from east to west have three Acacia riverine woodland associations; three deep valleys to the north of the area have dense riverine woodland with Celtis, Albizia, Euclea, Combretum, Acacia spp.; emergence of springs at Endulen feed a perennial stream with closed gallery forest with Ficus-Croton-Lepidotrichilia; and, finally, recent ash falls have produced immature alkaline soils with calcrete formation and short grass vegetation. All of these vegetation associations have been modified by human disturbance to greater or lesser degrees, and we have attempted to allow for this both by basing the associations on the least modified areas and by predicting how the associations, or parts of associations, have been altered by human action. Past land forms at Laetoli have been based on the geology and geomorphology of the area. Past vegetation patterns were estimated by superimposing present distributions of plant associations on equivalent landforms in the past, assuming similar climate to the present. This indicates the overall pattern of vegetation at Laetoli to have been a mosaic of low and tall deciduous woodlands and with riverine woodland and forest associations along water courses. Low woodlands would have been dominated by Acacia species, and tall woodlands by Combretum-Albizia species, with increasing increments of montane species, such as Croton species, to the east of the area. Riverine woodlands would have been dominated by Acacia-Euclea species, with wetter associations (downriver or linked with spring activity) supporting gallery forest with Ficus, Celtis, and Croton species. These are all species associations common in the area today, and with landforms little changed in the past, and assuming similar climate, there is every reason to predict that they would have been present in the past. Moreover, Pliocene environments lack the human disturbance that has destroyed much of the present day vegetation. Presence of woodlands is supported by fossil wood attributed to several of the tree species present in the area today and by similarities in the mammalian community structure between past and present. Having established the pattern for Pliocene vegetation based on climatic variables existing today, we then predict the effects of past variations in climate.

Reconstructing the Mexican Tropical Dry Forests via an Autoecological Niche Approach: Reconsidering the Ecosystem Boundaries

PubMed Central

Prieto-Torres, David A.; Rojas-Soto, Octavio R.

2016-01-01

We used Ecological Niche Modeling (ENM) of individual species of two taxonomic groups (plants and birds) in order to reconstruct the climatic distribution of Tropical Dry Forests (TDFs) in Mexico and to analyze their boundaries with other terrestrial ecosystems. The reconstruction for TDFs’ distribution was analyzed considering the prediction and omission errors based upon the combination of species, obtained from the overlap of individual models (only plants, only birds, and all species combined). Two verifications were used: a primary vegetation map and 100 independent TDFs localities. We performed a Principal Component (PCA) and Discriminant Analysis (DA) to evaluate the variation in the environmental variables and ecological overlap among ecosystems. The modeling strategies showed differences in the ecological patterns and prediction areas, where the “all species combined” model (with a threshold of ≥10 species) was the best strategy to use in the TDFs reconstruction. We observed a concordance of 78% with the primary vegetation map and a prediction of 98% of independent locality records. Although PCA and DA tests explained 75.78% and 97.9% of variance observed, respectively, we observed an important overlap among the TDFs with other adjacent ecosystems, confirming the existence of transition zones among them. We successfully modeled the distribution of Mexican TDFs using a number of bioclimatic variables and co-distributed species. This autoecological niche approach suggests the necessity of rethinking the delimitations of ecosystems based on the recognition of transition zones among them in order to understand the real nature of communities and association patterns of species. PMID:26968031

The influence of competition between plant functional types in the Canadian Terrestrial Ecosystem Model (CTEM) v. 2.0

NASA Astrophysics Data System (ADS)

Melton, Joe; Arora, Vivek

2015-04-01

The Canadian Terrestrial Ecosystem Model (CTEM) is the interactive vegetation component in the earth system modelling framework of the Canadian Centre for Climate Modelling and Analysis (CCCma). In its current framework, CTEM uses prescribed fractional coverage of plant functional types (PFTs) in each grid cell. In reality, vegetation cover is continually adjusting to changes in climate, atmospheric composition, and anthropogenic forcing, for example, through human-caused fires and CO2 fertilization. These changes in vegetation spatial patterns occur over timescales of years to centuries as tree migration is a slow process and vegetation distributions inherently have inertia. Here, we present version 2.0 of CTEM that includes a representation of competition between PFTs through a modified version of the Lotka-Volterra (L-V) predator-prey equations. The simulated areal extents of CTEM's seven non-crop PFTs are compared with available observation-based estimates, and simulations using unmodified L-V equations (similar to other models like TRIFFID), to demonstrate that the model is able to represent the broad spatial distributions of its seven PFTs at the global scale. Differences remain, however, since representing the multitude of plant species with just seven non-crop PFTs only allows the large scale climatic controls on the distributions of PFTs to be captured. As expected, PFTs that exist in climate niches are difficult to represent either due to the coarse spatial resolution of the model and the corresponding driving climate or the limited number of PFTs used to model the terrestrial ecosystem processes. The geographic and zonal distributions of primary terrestrial carbon pools and fluxes from the versions of CTEM that use prescribed and dynamically simulated fractional coverage of PFTs compare reasonably with each other and observation-based estimates. These results illustrate that the parametrization of competition between PFTs in CTEM behaves in a reasonably realistic manner while the use of unmodified L-V equations results in unrealistic plant distributions.

Determining bathymetric distributions of the eelgrass Zostera ...

EPA Pesticide Factsheets

Improved methods for determining bathymetric distributions of dominant intertidal plants throughout their estuarine range are needed. Zostera marina is a seagrass native to estuaries of the northeastern Pacific and many other sectors of the world ocean. The technique described here employed large format aerial photography using false color near-infrared film with digital image classification, and the production of digital bathymetric models of shallow estuaries such as those occurring in turbid waters of the Pacific Northwest USA. Application of geographic information system procedures to the eelgrass classifications and bathymetry distributions yielded digital bathymetric distributions based upon a very large number of observations. Similar bathymetric patterns were obtained for the three estuaries surveyed, and approximately 90% of the classified eelgrass occurred within the depth range -1.0 m to +1.0 m (MLLW). Comparison of these distributions with ground surveys of eelgrass lower depth limits indicated that the area of undetected subtidal eelgrass constituted 86% overall accuracy) in each estuary. The pattern of eelgrass in one estuary was distinctly different from those in the other two systems, illustrating the potential usefulness of this technique in exploring causative factors for such differences in estuarine intertidal vegetation distributions. Improved methods for determining bathymetric distributions of dominant intertidal plants throughout

[Effects of green space vegetation canopy pattern on the microclimate in residential quarters of Shenzhen City].

PubMed

Li, Ying-Han; Wang, Jun-Jian; Chen, Xue; Sun, Jian-Lin; Zeng, Hui

2011-02-01

Based on field survey and landscape pattern analysis, this paper studied the effects of green space vegetation canopy on the microclimate in three typical residential quarters in Shenzhen City. In each of the residential quarters, 22-26 points were chosen for meteorological observation; and around each of the observation points, a 20 m x 20 m quadrat was installed, with each quadrat divided into two different patches, one covered by vegetation canopy and the another no-covered. The patch density index (D(p)) and contagion index (CONTAG) in each quadrat were calculated to analyze the relationships between vegetation canopy pattern index and microclimate in each point. The results showed that the green space vegetation canopy pattern in Shenzhen had significant regulation effect on temperature and humidity. The cooling effect was mainly from the shading effect of vegetation, and also, correlated with vegetation quantity. The increase in the CONTAG of bare surface had obvious negative effects on the regulation effect of vegetation on microclimate. The regulation capability of green space vegetation on the temperature and humidity in residential quarters mainly came from tall arbor species.

The Role of Different Plant Soil-Water Feedbacks in Models of Dryland Vegetation Patterns

NASA Astrophysics Data System (ADS)

Silber, M.; Bonetti, S.; Gandhi, P.; Gowda, K.; Iams, S.; Porporato, A. M.

2017-12-01

Understanding the processes underlying the formation of regular vegetation patterns in arid and semi-arid regions is important to assessing desertification risk under increasing anthropogenic pressure. Various modeling frameworks have been proposed, which are all capable of generating similar patterns through self-organizing mechanisms that stem from assumptions about plant feedbacks on surface/subsurface water transport. We critically discuss a hierarchy of hydrology-vegetation models for the coupled dynamics of surface water, soil moisture, and vegetation biomass on a hillslope. We identify distinguishing features and trends for the periodic traveling wave solutions when there is an imposed idealized topography and make some comparisons to satellite images of large-scale banded vegetation patterns in drylands of Africa, Australia and North America. This work highlights the potential for constraining models by considerations of where the patterns may lie on a landscape, such as whether on a ridge or in a valley.

A study of the early detection of insect infestations and density/distribution of host plants. [Rio Grande

NASA Technical Reports Server (NTRS)

Hart, W. G. (Principal Investigator); Ingle, S. J.; Davis, M. R.

1975-01-01

The author has identified the following significant results. With comparative observations of film types and seasonal influences on reflectance characteristics, many crop varieties can be identified. This study shows that citrus, sugar cane, brush, some winter vegetables, and grain crops could be identified. Vegetative patterns in border areas can be detected. This information can be useful in detecting avenues of entry of pest species and areas of stress that require vigilance in stopping the spread of destructive species. Influence of some environmental factors on crops that may be confused with pest injury, or related factors, can be detected and identified with Skylab data (S-190B).

Patterns and variability of projected bioclimatic habitat for Pinus albicaulis in the Greater Yellowstone Area.

PubMed

Chang, Tony; Hansen, Andrew J; Piekielek, Nathan

2014-01-01

Projected climate change at a regional level is expected to shift vegetation habitat distributions over the next century. For the sub-alpine species whitebark pine (Pinus albicaulis), warming temperatures may indirectly result in loss of suitable bioclimatic habitat, reducing its distribution within its historic range. This research focuses on understanding the patterns of spatiotemporal variability for future projected P.albicaulis suitable habitat in the Greater Yellowstone Area (GYA) through a bioclimatic envelope approach. Since intermodel variability from General Circulation Models (GCMs) lead to differing predictions regarding the magnitude and direction of modeled suitable habitat area, nine bias-corrected statistically down-scaled GCMs were utilized to understand the uncertainty associated with modeled projections. P.albicaulis was modeled using a Random Forests algorithm for the 1980-2010 climate period and showed strong presence/absence separations by summer maximum temperatures and springtime snowpack. Patterns of projected habitat change by the end of the century suggested a constant decrease in suitable climate area from the 2010 baseline for both Representative Concentration Pathways (RCPs) 8.5 and 4.5 climate forcing scenarios. Percent suitable climate area estimates ranged from 2-29% and 0.04-10% by 2099 for RCP 8.5 and 4.5 respectively. Habitat projections between GCMs displayed a decrease of variability over the 2010-2099 time period related to consistent warming above the 1910-2010 temperature normal after 2070 for all GCMs. A decreasing pattern of projected P.albicaulis suitable habitat area change was consistent across GCMs, despite strong differences in magnitude. Future ecological research in species distribution modeling should consider a full suite of GCM projections in the analysis to reduce extreme range contractions/expansions predictions. The results suggest that restoration strageties such as planting of seedlings and controlling competing vegetation may be necessary to maintain P.albicaulis in the GYA under the more extreme future climate scenarios.

Patterns and Variability of Projected Bioclimatic Habitat for Pinus albicaulis in the Greater Yellowstone Area

PubMed Central

Chang, Tony; Hansen, Andrew J.; Piekielek, Nathan

2014-01-01

Projected climate change at a regional level is expected to shift vegetation habitat distributions over the next century. For the sub-alpine species whitebark pine (Pinus albicaulis), warming temperatures may indirectly result in loss of suitable bioclimatic habitat, reducing its distribution within its historic range. This research focuses on understanding the patterns of spatiotemporal variability for future projected P.albicaulis suitable habitat in the Greater Yellowstone Area (GYA) through a bioclimatic envelope approach. Since intermodel variability from General Circulation Models (GCMs) lead to differing predictions regarding the magnitude and direction of modeled suitable habitat area, nine bias-corrected statistically down-scaled GCMs were utilized to understand the uncertainty associated with modeled projections. P.albicaulis was modeled using a Random Forests algorithm for the 1980–2010 climate period and showed strong presence/absence separations by summer maximum temperatures and springtime snowpack. Patterns of projected habitat change by the end of the century suggested a constant decrease in suitable climate area from the 2010 baseline for both Representative Concentration Pathways (RCPs) 8.5 and 4.5 climate forcing scenarios. Percent suitable climate area estimates ranged from 2–29% and 0.04–10% by 2099 for RCP 8.5 and 4.5 respectively. Habitat projections between GCMs displayed a decrease of variability over the 2010–2099 time period related to consistent warming above the 1910–2010 temperature normal after 2070 for all GCMs. A decreasing pattern of projected P.albicaulis suitable habitat area change was consistent across GCMs, despite strong differences in magnitude. Future ecological research in species distribution modeling should consider a full suite of GCM projections in the analysis to reduce extreme range contractions/expansions predictions. The results suggest that restoration strageties such as planting of seedlings and controlling competing vegetation may be necessary to maintain P.albicaulis in the GYA under the more extreme future climate scenarios. PMID:25372719

The landscape of fear as an emergent property of heterogeneity: Contrasting patterns of predation risk in grassland ecosystems.

PubMed

Atuo, Fidelis Akunke; O'Connell, Timothy John

2017-07-01

The likelihood of encountering a predator influences prey behavior and spatial distribution such that non-consumptive effects can outweigh the influence of direct predation. Prey species are thought to filter information on perceived predator encounter rates in physical landscapes into a landscape of fear defined by spatially explicit heterogeneity in predation risk. The presence of multiple predators using different hunting strategies further complicates navigation through a landscape of fear and potentially exposes prey to greater risk of predation. The juxtaposition of land cover types likely influences overlap in occurrence of different predators, suggesting that attributes of a landscape of fear result from complexity in the physical landscape. Woody encroachment in grasslands furnishes an example of increasing complexity with the potential to influence predator distributions. We examined the role of vegetation structure on the distribution of two avian predators, Red-tailed Hawk ( Buteo jamaicensis ) and Northern Harrier ( Circus cyaneus ), and the vulnerability of a frequent prey species of those predators, Northern Bobwhite ( Colinus virginianus ). We mapped occurrences of the raptors and kill locations of Northern Bobwhite to examine spatial vulnerability patterns in relation to landscape complexity. We use an offset model to examine spatially explicit habitat use patterns of these predators in the Southern Great Plains of the United States, and monitored vulnerability patterns of their prey species based on kill locations collected during radio telemetry monitoring. Both predator density and predation-specific mortality of Northern Bobwhite increased with vegetation complexity generated by fine-scale interspersion of grassland and woodland. Predation pressure was lower in more homogeneous landscapes where overlap of the two predators was less frequent. Predator overlap created areas of high risk for Northern Bobwhite amounting to 32% of the land area where landscape complexity was high and 7% where complexity was lower. Our study emphasizes the need to evaluate the role of landscape structure on predation dynamics and reveals another threat from woody encroachment in grasslands.

Evaluation of Vertical Lacunarity Profiles in Forested Areas Using Airborne Laser Scanning Point Clouds

NASA Astrophysics Data System (ADS)

Székely, B.; Kania, A.; Standovár, T.; Heilmeier, H.

2016-06-01

The horizontal variation and vertical layering of the vegetation are important properties of the canopy structure determining the habitat; three-dimensional (3D) distribution of objects (shrub layers, understory vegetation, etc.) is related to the environmental factors (e.g., illumination, visibility). It has been shown that gaps in forests, mosaic-like structures are essential to biodiversity; various methods have been introduced to quantify this property. As the distribution of gaps in the vegetation is a multi-scale phenomenon, in order to capture it in its entirety, scale-independent methods are preferred; one of these is the calculation of lacunarity. We used Airborne Laser Scanning point clouds measured over a forest plantation situated in a former floodplain. The flat topographic relief ensured that the tree growth is independent of the topographic effects. The tree pattern in the plantation crops provided various quasi-regular and irregular patterns, as well as various ages of the stands. The point clouds were voxelized and layers of voxels were considered as images for two-dimensional input. These images calculated for a certain vicinity of reference points were taken as images for the computation of lacunarity curves, providing a stack of lacunarity curves for each reference points. These sets of curves have been compared to reveal spatial changes of this property. As the dynamic range of the lacunarity values is very large, the natural logarithms of the values were considered. Logarithms of lacunarity functions show canopy-related variations, we analysed these variations along transects. The spatial variation can be related to forest properties and ecology-specific aspects.

Seasonal distribution, aggregation, and habitat selection of common carp in Clear Lake, Iowa

USGS Publications Warehouse

Penne, C.R.; Pierce, C.L.

2008-01-01

The common carp Cyprinus carpio is widely distributed and frequently considered a nuisance species outside its native range. Common carp are abundant in Clear Lake, Iowa, where their presence is both a symptom of degradation and an impediment to improving water quality and the sport fishery. We used radiotelemetry to quantify seasonal distribution, aggregation, and habitat selection of adult and subadult common carp in Clear Lake during 2005-2006 in an effort to guide future control strategies. Over a 22-month period, we recorded 1,951 locations of 54 adults and 60 subadults implanted with radio transmitters. Adults demonstrated a clear tendency to aggregate in an offshore area during the late fall and winter and in shallow, vegetated areas before and during spring spawning. Late-fall and winter aggregations were estimated to include a larger percentage of the tracked adults than spring aggregations. Subadults aggregated in shallow, vegetated areas during the spring and early summer. Our study, when considered in combination with previous research, suggests repeatable patterns of distribution, aggregation, and habitat selection that should facilitate common carp reduction programs in Clear Lake and similar systems. ?? Copyright by the American Fisheries Society 2008.

A novel approach for modelling vegetation distributions and analysing vegetation sensitivity through trait-climate relationships in China

PubMed Central

Yang, Yanzheng; Zhu, Qiuan; Peng, Changhui; Wang, Han; Xue, Wei; Lin, Guanghui; Wen, Zhongming; Chang, Jie; Wang, Meng; Liu, Guobin; Li, Shiqing

2016-01-01

Increasing evidence indicates that current dynamic global vegetation models (DGVMs) have suffered from insufficient realism and are difficult to improve, particularly because they are built on plant functional type (PFT) schemes. Therefore, new approaches, such as plant trait-based methods, are urgently needed to replace PFT schemes when predicting the distribution of vegetation and investigating vegetation sensitivity. As an important direction towards constructing next-generation DGVMs based on plant functional traits, we propose a novel approach for modelling vegetation distributions and analysing vegetation sensitivity through trait-climate relationships in China. The results demonstrated that a Gaussian mixture model (GMM) trained with a LMA-Nmass-LAI data combination yielded an accuracy of 72.82% in simulating vegetation distribution, providing more detailed parameter information regarding community structures and ecosystem functions. The new approach also performed well in analyses of vegetation sensitivity to different climatic scenarios. Although the trait-climate relationship is not the only candidate useful for predicting vegetation distributions and analysing climatic sensitivity, it sheds new light on the development of next-generation trait-based DGVMs. PMID:27052108

β-Catenin is essential for patterning the maternally specified animal-vegetal axis in the sea urchin embryo

PubMed Central

Wikramanayake, Athula H.; Huang, Ling; Klein, William H.

1998-01-01

In sea urchin embryos, the animal-vegetal axis is specified during oogenesis. After fertilization, this axis is patterned to produce five distinct territories by the 60-cell stage. Territorial specification is thought to occur by a signal transduction cascade that is initiated by the large micromeres located at the vegetal pole. The molecular mechanisms that mediate the specification events along the animal–vegetal axis in sea urchin embryos are largely unknown. Nuclear β-catenin is seen in vegetal cells of the early embryo, suggesting that this protein plays a role in specifying vegetal cell fates. Here, we test this hypothesis and show that β-catenin is necessary for vegetal plate specification and is also sufficient for endoderm formation. In addition, we show that β-catenin has pronounced effects on animal blastomeres and is critical for specification of aboral ectoderm and for ectoderm patterning, presumably via a noncell-autonomous mechanism. These results support a model in which a Wnt-like signal released by vegetal cells patterns the early embryo along the animal–vegetal axis. Our results also reveal similarities between the sea urchin animal–vegetal axis and the vertebrate dorsal–ventral axis, suggesting that these axes share a common evolutionary origin. PMID:9689082

[Temporal and spatial variation of MODIS vegetation indices in Hunan Province].

PubMed

Lin, Hui; Xiong, Yu-Jiu; Wan, Ling-Feng; Mo, Deng-Kui; Sun, Hua

2007-03-01

Based on MODIS images and by using the algorithm of maximum value composite (MVC), the monthly vegetation indices (VIs) in 2005 in Hunan Province were obtained. Through the analysis of the MODIS VIs, Hunan Province was divided into six districts to describe the spatial distribution of the VIs, and by using the monthly mean temperature and rainfall data collected from 5 climatic monitoring stations in this province, the temporal variation of the VIs was analyzed. The results showed that the spatial distribution of MODIS VIs was positively correlated with vegetation cover, and appeared regional characteristics. The MODIS VIs varied with season, and the curves of their monthly mean values were downwards opening quadratic parabolas, with the maximum appeared in July. The value of MODIS EVI was smaller than that of MODIS NDVI. MODIS VI was mainly affected by monthly mean temperature, but this effect was decreased with decreasing latitude. The variation pattern of MODIS EVI was more apparent than that of MODIS NDVI, i. e. , the quadratic parabola of MODIS EVI was smoother, going gradually from minimum to maximum and then going down, while that of MODIS NDVI had tiny fluctuations on both sides of the maximum point.

Environmental impacts on the southern Florida coastal waters: a history of change in Florida Bay

USGS Publications Warehouse

Brewster-Wingard, G. L.; Ishman, S. E.; Holmes, C. W.

1998-01-01

Analyses of four cores located in the northern transitional, eastern, and central portions of Florida Bay reveal historical patterns of change in salinity and seagrass distribution. Salinity and the distribution of seagrass beds are two critical issues for the restoration of Florida Bay. The distribution of benthic fauna in Bob Allen 6A and Russell Bank 19B cores illustrates changes in environmental parameters prior to 1900. Natural fluctuations occur in salinity, but the amplitude of those fluctuations was limited to a 15–20% shift about the mean. Subtle changes occur in the benthic fauna around 1910, but beginning around 1940, the pattern of salinity fluctuation departs substantially from the pre-1900 pattern. Post-1940, the salinity oscillates 40–60% about the mean. This pattern is seen in all indicators measured. Around 1970, a significant but short term decline occurred in salinity. The Taylor Creek T24 core from the northern transitional zone reflects changes in freshwater flow that have occurred during this century. The upper portion of the core records a significant increase in salinity, with a slight decrease occurring in recent years. The Pass Key 37 core represents an area of very high sedimentation rates; an increase in salinity occurs in the upper portion of the core. Natural fluctuations in seagrass distribution are inferred from the shifts in relative abundance of epiphytal species preserved in the cores. All four cores show an increase in epiphytes and therefore in seagrass coverage during this century. An increase also occurs in epiphytal species that can dwell on either Thalassia or macro-algal mats associated with Thalassia beds. These data suggest an increase in algal-mats has occurred during this century. The Bob Allen 6A core records an extensive period during the 1800's of little to no vegetative cover of the substrate based on the near absence of epiphytic species in that segment of the core. Following this period, the epiphytal species increase rapidly in abundance, implying that vegetation may have the ability to disseminate rapidly.

A study to explore the use of orbital remote sensing to determine native arid plant distribution. [Arizona

NASA Technical Reports Server (NTRS)

Mcginnies, W. G. (Principal Investigator); Conn, J. S.; Haase, E. F.; Lepley, L. K.; Musick, H. B.; Foster, K. E.

1975-01-01

The author has identified the following significant results. Research results include a method for determining the reflectivities of natural areas from ERTS data taking into account sun angle and atmospheric effects on the radiance seen by the satellite sensor. Ground truth spectral signature data for various types of scenes, including ground with and without annuals, and various shrubs were collected. Large areas of varnished desert pavement are visible and mappable on ERTS and high altitude aircraft imagery. A large scale and a small scale vegetation pattern were found to be correlated with presence of desert pavement. A comparison of radiometric data with video recordings shows quantitatively that for most areas of desert vegetation, soils are the most influential factor in determining the signature of a scene. Additive and subtractive image processing techniques were applied in the dark room to enhance vegetational aspects of ERTS.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Graham, Emily B.; Tfaily, Malak M.; Crump, Alex R.

In light of increasing terrestrial carbon (C) transport across aquatic boundaries, the mechanisms governing organic carbon (OC) oxidation along terrestrial-aquatic interfaces are crucial to future climate predictions. Here, we investigate biochemistry, metabolic pathways, and thermodynamics corresponding to OC oxidation in the Columbia River corridor. We leverage natural vegetative differences to encompass variation in terrestrial C inputs. Our results suggest that decreases in terrestrial C deposition associated with diminished riparian vegetation induce oxidation of physically-bound (i.e., mineral and microbial) OC at terrestrial-aquatic interfaces. We also find that contrasting metabolic pathways oxidize OC in the presence and absence of vegetation and—in directmore » conflict with the concept of ‘priming’—that inputs of water-soluble and thermodynamically-favorable terrestrial OC protects bound-OC from oxidation. Based on our results, we propose a mechanistic conceptualization of OC oxidation along terrestrial-aquatic interfaces that can be used to model heterogeneous patterns of OC loss under changing land cover distributions.« less

Vegetation as a tool in the interpretation of fluvial geomorphic processes and landforms

USGS Publications Warehouse

Hupp, Cliff R.; Dufour, S; Bornette, G

2016-01-01

This chapter exemplifies that vegetation can be used as a tool for geomorphic interpretation in several major ways. It presents a general overview: through dendrogeomorphic analysis (tree rings) to estimate the timing of important geomorphic events including floods and mass wasting and to estimate rates of erosion and sedimentation; through the documentation and interpretation of species distributional patterns that are established in response to prevailing hydrogeomorphic conditions; and through the role that it plays, depending on size, shape and growth form, in flow rates and subsequent erosion and deposition processes. Floods, from prolonged inundation characteristic of relatively large, low-gradient basins to high-gradient and short-period destructive events, are the most important extrinsic factor in bottomland systems. Vegetation organization, composition and plant community dynamics on river floodplains are controlled by disturbance type and scale, and biological characteristics of plants linked to resistance to disturbance, resilience and competitive ability.

Variability of pesticide exposure in a stream mesocosm system: macrophyte-dominated vs. non-vegetated sections.

PubMed

Beketov, Mikhail A; Liess, Matthias

2008-12-01

For flowing water bodies no information is available about patterns of contaminant distribution in flowing water compared to macrophyte-dominated structures. The aim of the study was to examine temporal dynamic and spatial cross-channel variability of pulse exposure of the insecticide thiacloprid in outdoor stream mesocosms. Two distinct cross-channel sections have been considered: macrophyte-dominated littoral and non-vegetated midstream. Median disappearance time ranged from 17 to 43 h (water phase, midstream). We showed that during the exposure pulse (10h) thiacloprid concentrations in the macrophyte-dominated section were 20-60% lower than those in the non-vegetated section. This suggests that spatial variability in contaminant concentrations, particularly in streams containing macrophytes, should be taken into account to enable a more realistic assessment of (i) exposure and associated effects and (ii) mass transport of pesticides and other chemicals into river systems (e.g. losses with surface runoff).

Spatial distribution of soil organic carbon and its influencing factors in desert grasslands of the Hexi Corridor, northwest China.

PubMed

Wang, Min; Su, Yongzhong; Yang, Xiao

2014-01-01

Knowledge of the distribution patterns of soil organic carbon (SOC) and factors that influence these patterns is crucial for understanding the carbon cycle. The objectives of this study were to determine the spatial distribution pattern of soil organic carbon density (SOCD) and the controlling factors in arid desert grasslands of northwest China. The above- and belowground biomass and SOCD in 260 soil profiles from 52 sites over 2.7×10(4) km2 were investigated. Combined with a satellite-based dataset of an enhanced vegetation index during 2011-2012 and climatic factors at different sites, the relationships between SOCD and biotic and abiotic factors were identified. The results indicated that the mean SOCD was 1.20 (SD:+/- 0.85), 1.73 (SD:+/- 1.20), and 2.69 (SD:+/- 1.91) kg m(-2) at soil depths of 0-30 cm, 0-50 cm, and 0-100 cm, respectively, which was smaller than other estimates in temperate grassland, steppe, and desert-grassland ecosystems. The spatial distribution of SOCD gradually decreased from the southeast to the northwest, corresponding to the precipitation gradient. SOCD increased significantly with vegetation biomass, annual precipitation, soil moisture, clay and silt content, and decreased with mean annual temperature and sand content. The correlation between BGB and SOCD was closer than the correlation between AGB and SOCD. Variables could together explain about 69.8%, 74.4%, and 78.9% of total variation in SOCD at 0-30 cm, 0-50 cm, and 0-100 cm, respectively. In addition, we found that mean annual temperature is more important than other abiotic factors in determining SOCD in arid desert grasslands in our study area. The information obtained in this study provides a basis for accurately estimating SOC stocks and assessing carbon (C) sequestration potential in the desert grasslands of northwest China.

Using the satellite-derived normalized difference vegetation index (NDVI) to explain ranging patterns in a lek-breeding antelope: the importance of scale.

PubMed

Bro-Jørgensen, Jakob; Brown, Molly E; Pettorelli, Nathalie

2008-11-01

Lek-breeding species are characterized by a negative association between territorial resource availability and male mating success; however, the impact of resources on the overall distribution patterns of the two sexes in lek systems is not clear. The normalized difference vegetation index (NDVI) has recently emerged as a powerful proxy measure for primary productivity, allowing the links between the distributions of animals and resources to be explored. Using NDVI at four spatial resolutions, we here investigate how the distribution of the two sexes in a lek-breeding population of topi antelopes relates to resource abundance before and during the rut. We found that in the dry season preceding the rut, topi density correlated positively with NDVI at the large, but not the fine, scale. This suggests that before the rut, when resources were relatively scant, topi preferred pastures where green grass was widely abundant. The pattern was less pronounced in males, suggesting that the need for territorial attendance prevents males from tracking resources as freely as females do. During the rut, which occurs in the wet season, both male and female densities correlated negatively with NDVI at the fine scale. At this time, resources were generally plentiful and the results suggest that, rather than by resource maximization, distribution during the rut was determined by benefits of aggregating on relatively resource-poor leks for mating, and possibly antipredator, purposes. At the large scale, no correlation between density and NDVI was found during the rut in either sex, which can be explained by leks covering areas too small to be reflected at this resolution. The study illustrates that when investigating spatial organization, it is important: (1) to choose the appropriate analytic scale, and (2) to consider behavioural as well as strictly ecological factors.

Soil moisture and vegetation patterns in northern California forests

Treesearch

James R. Griffin

1967-01-01

Twenty-nine soil-vegetation plots were studied in a broad transect across the southern Cascade Range. Variations in soil moisture patterns during the growing season and in soil moisture tension values are discussed. Plot soil moisture values for 40- and 80-cm. depths in August and September are integrated into a soil drought index. Vegetation patterns are described in...

Spatial and temporal functional changes in alpine summit vegetation are driven by increases in shrubs and graminoids.

PubMed

Venn, Susanna; Pickering, Catherine; Green, Ken

2014-01-01

Classical approaches to investigating temporal and spatial changes in community composition offer only partial insight into the ecology that drives species distribution, community patterns and processes, whereas a functional approach can help to determine many of the underlying mechanisms that drive such patterns. Here, we aim to bring these two approaches together to understand such drivers, using an elevation gradient of sites, a repeat species survey and species functional traits. We used data from a repeat vegetation survey on five alpine summits and measured plant height, leaf area, leaf dry matter content and specific leaf area (SLA) for every species recorded in the surveys. We combined species abundances with trait values to produce a community trait-weighted mean (CTWM) for each trait, and then combined survey results with the CTWMs. Across the gradient of summits, more favourable conditions for plant growth (warmer, longer growing season) occurred at the lower elevations. Vegetation composition changes between 2004 and 2011 (according to non-metric multi-dimensional scaling ordination) were strongly affected by the high and increasing abundance of species with high SLA at high elevations. Species life-form categories strongly affected compositional changes and functional composition, with increasing dominance of tall shrubs and graminoids at the lower-elevation summits, and an overall increase in graminoids across the gradient. The CTWM for plant height and leaf dry matter content significantly decreased with elevation, whereas for leaf area and SLA it significantly increased. The significant relationships between CTWM and elevation may suggest specific ecological processes, namely plant competition and local productivity, influencing vegetation preferentially across the elevation gradient, with the dominance of shrubs and graminoids driving the patterns in the CTWMs.

Spatial and temporal functional changes in alpine summit vegetation are driven by increases in shrubs and graminoids

PubMed Central

Venn, Susanna; Pickering, Catherine; Green, Ken

2014-01-01

Classical approaches to investigating temporal and spatial changes in community composition offer only partial insight into the ecology that drives species distribution, community patterns and processes, whereas a functional approach can help to determine many of the underlying mechanisms that drive such patterns. Here, we aim to bring these two approaches together to understand such drivers, using an elevation gradient of sites, a repeat species survey and species functional traits. We used data from a repeat vegetation survey on five alpine summits and measured plant height, leaf area, leaf dry matter content and specific leaf area (SLA) for every species recorded in the surveys. We combined species abundances with trait values to produce a community trait-weighted mean (CTWM) for each trait, and then combined survey results with the CTWMs. Across the gradient of summits, more favourable conditions for plant growth (warmer, longer growing season) occurred at the lower elevations. Vegetation composition changes between 2004 and 2011 (according to non-metric multi-dimensional scaling ordination) were strongly affected by the high and increasing abundance of species with high SLA at high elevations. Species life-form categories strongly affected compositional changes and functional composition, with increasing dominance of tall shrubs and graminoids at the lower-elevation summits, and an overall increase in graminoids across the gradient. The CTWM for plant height and leaf dry matter content significantly decreased with elevation, whereas for leaf area and SLA it significantly increased. The significant relationships between CTWM and elevation may suggest specific ecological processes, namely plant competition and local productivity, influencing vegetation preferentially across the elevation gradient, with the dominance of shrubs and graminoids driving the patterns in the CTWMs. PMID:24790129

Angiosperm n-alkane distribution patterns and the geologic record of C4 grassland evolution

NASA Astrophysics Data System (ADS)

Henderson, A.; Graham, H. V.; Patzkowsky, M.; Fox, D. L.; Freeman, K. H.

2012-12-01

n-Alkane average chain-length (ACL) patterns vary regionally with community composition and climate. To clarify the influence of phylogenetic and community patterns, we compiled and analyzed a global database of published n-alkane abundance for n-C27 to C35 homologs in modern plant specimens (n=205). ACL for waxes in C4 non-woody plants are longer than for woody plants, suggesting ACL can serve as an indicator of the three-dimensional structure of local vegetation. Further, these findings suggest compound-specific isotopic data for longer alkane homologs (C31, C33, C35) will proportionately represent non-woody vegetation and isotope measurements of C29 are more representative of woody vegetation. Thus, the combination of ACL and carbon isotope compositions should allow us to disentangle C3 woody, C3 non-woody, and C4 non-woody signals in terrestrial paleorecords. Application of this approach to the geologic record of Miocene C4 grassland expansion in the US Great Plains and the Siwaliks in Pakistan illustrate two very different transition scenarios. Alkane-specific isotopic data indicate C4 grasslands appeared 2.5 Ma in the Great Plains and 6.5 Ma in the Siwaliks, and ACL analysis indicates that this transition involved the replacement of woody vegetation in the US and the replacement of C3 grasses in Pakistan. Our analysis illustrates that, consistent with differences in the timing of C4 grassland, the drivers of change were likely not the same in these regions. Oxygen isotope records suggest that the more recent transition in the Great Plains was associated with climate cooling and possibly changes in disturbance regimes and that the transition in the Siwaliks was likely associated with warming and drying.

Polar localization of plasma membrane Ca2+/Mg2+ ATPase correlates with the pattern of steady ionic currents in eggs ofLymnaea stagnalis andBithynia tentaculata (Mollusca).

PubMed

Zivkovic, Danica; Créton, Robbert; Zwaan, Gideon; de Bruijn, Willem C; Dohmen, M René

1990-11-01

During extrusion of the first polar body in eggs ofLymnaea stagnalis andBithynia tentaculata a localized Ca 2+ /Mg 2+ ATPase activity was detected, using Ando's enzyme-cytochemical method for electron microscopy [Ando et al. (1981) Acta Histochem Cytochem 14:705-726]. The enzyme activity was distributed in a polar fashion, along the cytoplasmic face of the plasma membrane. In the eggs ofLymnaea it was found only in the vegetal hemisphere, whereas inBithynia eggs it was localized both in the vegetal hemisphere and at the animal pole. This pattern of enzyme activity corresponds to the polar pattern of transcellular ionic currents measured with the vibrating probe, which we showed to be partially carried or regulated by calcium [Zivkovic and Dohmen (1989) Biol Bull (Woods Hole) 176 (Suppl):103-109]. The characteristics of the ATPase were studied using a variety of approaches such as ion and substrate depletions and substitutions, addition of specific inhibitors of ATPase activity, treatment with EDTA/EGTA and electron energy-loss spectrometry. The results indicate that, inLymnaea, there are at least two enzymatic entities. The first one is a Ca 2+ /Mg 2+ ATPase localized along the membrane and in the cortex of the vegetal hemisphere. The second one is a Ca 2+ -stimulated ATPase (calcium pump of the plasma membrane) localized in a small region of the membrane at the vegetal pole. We speculate that in the eggs ofLymnaea andBithynia a functional relationship exists between the plasma-membrane-associated ATPase activity and the transcellular ionic currents measured in the same region.

Predicting the effect of fire on large-scale vegetation patterns in North America.

Treesearch

Donald McKenzie; David L. Peterson; Ernesto. Alvarado

1996-01-01

Changes in fire regimes are expected across North America in response to anticipated global climatic changes. Potential changes in large-scale vegetation patterns are predicted as a result of altered fire frequencies. A new vegetation classification was developed by condensing Kuchler potential natural vegetation types into aggregated types that are relatively...

Trends in Soil Moisture Reflect More Than Slope Position: Soils on San Cristóbal Island, Galápagos as a Case Study

NASA Astrophysics Data System (ADS)

Percy, M.; Singha, K.; Benninger, L. K.; Riveros-Iregui, D. A.; Mirus, B. B.

2015-12-01

The spatial and temporal distribution of soil moisture in tropical critical zones depends upon a number of variables including topographic position, soil texture, overlying vegetation, and local microclimates. We investigate the influences on soil moisture on a tropical basaltic island (San Cristóbal, Galápagos) across a variety of microclimates during the transition from the wetter to the drier season. We used multiple approaches to characterize spatial and temporal patterns in soil moisture at four sites across microclimates ranging from arid to very humid. The microclimates on San Cristóbal vary with elevation, so our monitoring includes two sites in the transitional zone at lower elevations, one in the humid zone at moderate elevations, and one in the very humid zone in higher elevations. We made over 250 near-surface point measurements per site using a Hydrosense II probe, and estimated the lateral variability in soil moisture across each site with an EM-31 electrical conductivity meter. We also monitored continuous time-series of in-situ soil moisture dynamics using three nested TDR probes collocated with meteorological stations at each of the sites. Preliminary analysis indicates that soils in the very humid zone have lower electrical conductivities across all the hillslopes as compared to the humid and transitional zones, which suggests that additional factors beyond climate and slope position are important. While soil texture across the very humid site is fairly uniform, variations in vegetation have a strong control on soil moisture patterns. At the remaining sites the vegetation patterns also have a very strong local influence on soil moisture, but correlation between the depth to clay layers and soil moisture patterns suggests that mineralogy is also important. Our findings suggest that the microclimatic setting is a crucial consideration for understanding relations between vegetation, soil texture, and soil-moisture dynamics in tropical critical zones.

Random Distribution Pattern and Non-adaptivity of Genome Size in a Highly Variable Population of Festuca pallens

PubMed Central

Šmarda, Petr; Bureš, Petr; Horová, Lucie

2007-01-01

Background and Aims The spatial and statistical distribution of genome sizes and the adaptivity of genome size to some types of habitat, vegetation or microclimatic conditions were investigated in a tetraploid population of Festuca pallens. The population was previously documented to vary highly in genome size and is assumed as a model for the study of the initial stages of genome size differentiation. Methods Using DAPI flow cytometry, samples were measured repeatedly with diploid Festuca pallens as the internal standard. Altogether 172 plants from 57 plots (2·25 m2), distributed in contrasting habitats over the whole locality in South Moravia, Czech Republic, were sampled. The differences in DNA content were confirmed by the double peaks of simultaneously measured samples. Key Results At maximum, a 1·115-fold difference in genome size was observed. The statistical distribution of genome sizes was found to be continuous and best fits the extreme (Gumbel) distribution with rare occurrences of extremely large genomes (positive-skewed), as it is similar for the log-normal distribution of the whole Angiosperms. Even plants from the same plot frequently varied considerably in genome size and the spatial distribution of genome sizes was generally random and unautocorrelated (P > 0·05). The observed spatial pattern and the overall lack of correlations of genome size with recognized vegetation types or microclimatic conditions indicate the absence of ecological adaptivity of genome size in the studied population. Conclusions These experimental data on intraspecific genome size variability in Festuca pallens argue for the absence of natural selection and the selective non-significance of genome size in the initial stages of genome size differentiation, and corroborate the current hypothetical model of genome size evolution in Angiosperms (Bennetzen et al., 2005, Annals of Botany 95: 127–132). PMID:17565968

Multiple Scales of Control on the Structure and Spatial Distribution of Woody Vegetation in African Savanna Watersheds

PubMed Central

Vaughn, Nicholas R.; Asner, Gregory P.; Smit, Izak P. J.; Riddel, Edward S.

2015-01-01

Factors controlling savanna woody vegetation structure vary at multiple spatial and temporal scales, and as a consequence, unraveling their combined effects has proven to be a classic challenge in savanna ecology. We used airborne LiDAR (light detection and ranging) to map three-dimensional woody vegetation structure throughout four savanna watersheds, each contrasting in geologic substrate and climate, in Kruger National Park, South Africa. By comparison of the four watersheds, we found that geologic substrate had a stronger effect than climate in determining watershed-scale differences in vegetation structural properties, including cover, height and crown density. Generalized Linear Models were used to assess the spatial distribution of woody vegetation structural properties, including cover, height and crown density, in relation to mapped hydrologic, topographic and fire history traits. For each substrate and climate combination, models incorporating topography, hydrology and fire history explained up to 30% of the remaining variation in woody canopy structure, but inclusion of a spatial autocovariate term further improved model performance. Both crown density and the cover of shorter woody canopies were determined more by unknown factors likely to be changing on smaller spatial scales, such as soil texture, herbivore abundance or fire behavior, than by our mapped regional-scale changes in topography and hydrology. We also detected patterns in spatial covariance at distances up to 50–450 m, depending on watershed and structural metric. Our results suggest that large-scale environmental factors play a smaller role than is often attributed to them in determining woody vegetation structure in southern African savannas. This highlights the need for more spatially-explicit, wide-area analyses using high resolution remote sensing techniques. PMID:26660502

Multiple Scales of Control on the Structure and Spatial Distribution of Woody Vegetation in African Savanna Watersheds.

PubMed

Vaughn, Nicholas R; Asner, Gregory P; Smit, Izak P J; Riddel, Edward S

2015-01-01

Factors controlling savanna woody vegetation structure vary at multiple spatial and temporal scales, and as a consequence, unraveling their combined effects has proven to be a classic challenge in savanna ecology. We used airborne LiDAR (light detection and ranging) to map three-dimensional woody vegetation structure throughout four savanna watersheds, each contrasting in geologic substrate and climate, in Kruger National Park, South Africa. By comparison of the four watersheds, we found that geologic substrate had a stronger effect than climate in determining watershed-scale differences in vegetation structural properties, including cover, height and crown density. Generalized Linear Models were used to assess the spatial distribution of woody vegetation structural properties, including cover, height and crown density, in relation to mapped hydrologic, topographic and fire history traits. For each substrate and climate combination, models incorporating topography, hydrology and fire history explained up to 30% of the remaining variation in woody canopy structure, but inclusion of a spatial autocovariate term further improved model performance. Both crown density and the cover of shorter woody canopies were determined more by unknown factors likely to be changing on smaller spatial scales, such as soil texture, herbivore abundance or fire behavior, than by our mapped regional-scale changes in topography and hydrology. We also detected patterns in spatial covariance at distances up to 50-450 m, depending on watershed and structural metric. Our results suggest that large-scale environmental factors play a smaller role than is often attributed to them in determining woody vegetation structure in southern African savannas. This highlights the need for more spatially-explicit, wide-area analyses using high resolution remote sensing techniques.

Assessing vegetation structure and ANPP dynamics in a grassland-shrubland Chihuahuan ecotone using NDVI-rainfall relationships

NASA Astrophysics Data System (ADS)

Moreno-de las Heras, M.; Diaz-Sierra, R.; Turnbull, L.; Wainwright, J.

2015-01-01

Climate change and the widespread alteration of natural habitats are major drivers of vegetation change in drylands. A classic case of vegetation change is the shrub-encroachment process that has been taking place over the last 150 years in the Chihuahuan Desert, where large areas of grasslands dominated by perennial grass species (black grama, Bouteloua eriopoda, and blue grama, B. gracilis) have transitioned to shrublands dominated by woody species (creosotebush, Larrea tridentata, and mesquite, Prosopis glandulosa), accompanied by accelerated water and wind erosion. Multiple mechanisms drive the shrub-encroachment process, including exogenous triggering factors such as precipitation variations and land-use change, and endogenous amplifying mechanisms brought about by soil erosion-vegetation feedbacks. In this study, simulations of plant biomass dynamics with a simple modelling framework indicate that herbaceous (grasses and forbs) and shrub vegetation in drylands have different responses to antecedent precipitation due to functional differences in plant growth and water-use patterns, and therefore shrub encroachment may be reflected in the analysis of landscape-scale vegetation-rainfall relationships. We analyze the structure and dynamics of vegetation at an 18 km2 grassland-shrubland ecotone in the northern edge of the Chihuahuan Desert (McKenzie Flats, Sevilleta National Wildlife Refuge, NM, USA) by investigating the relationship between decade-scale (2000-2013) records of medium-resolution remote sensing of vegetation greenness (MODIS NDVI) and precipitation. Spatial evaluation of NDVI-rainfall relationship at the studied ecotone indicates that herbaceous vegetation shows quick growth pulses associated with short-term (previous 2 months) precipitation, while shrubs show a slow response to medium-term (previous 5 months) precipitation. We use these relationships to (a) classify landscape types as a function of the spatial distribution of dominant vegetation, and to (b) decompose the NDVI signal into partial primary production components for herbaceous vegetation and shrubs across the study site. We further apply remote-sensed annual net primary production (ANPP) estimations and landscape type classification to explore the influence of inter-annual variations in seasonal precipitation on the production of herbaceous and shrub vegetation. Our results suggest that changes in the amount and temporal pattern of precipitation comprising reductions in monsoonal summer rainfall and/or increases in winter precipitation may enhance the shrub-encroachment process in desert grasslands of the American Southwest.

Groundwater controls on river channel pattern

NASA Astrophysics Data System (ADS)

Bätz, Nico; Colombini, Pauline; Cherubini, Paolo; Lane, Stuart N.

2017-04-01

Braided rivers are characterized by high rates of morphological change. However, despite the potential for frequent disturbance, vegetated patches may develop within this system and influence long-term channel dynamics and channel patterns through the "engineering effects" of vegetation. The stabilizing effect of developing vegetation on morphological change has been widely shown by flume experiments and (historic) aerial pictures analysis. Thus, there is a balance between disturbance and stabilization, mediated through vegetation, that may determine the long-term geomorphic and biogeomorphic evolution of the river. It follows that with a change in disturbance frequency relative to the rate of vegetation establishment, a systematic geomorphological shift could occur. Research has addressed how changes in disturbance frequency affect river channel pattern, but has rarely addressed the way in which the stabilizing effects of biogeomorphic succession interact with disturbance frequency to maintain a river in a more dynamic or a less dynamic state. Here, we quantify how the interplay between groundwater access, disturbance frequency and vegetation succession, drive changes in channel pattern. We studied this complex interplay on a transitional gravel-bed river system (braided, wandering, meandering) close to Geneva (Switzerland) - the Allondon River. Dendroecological analysis demonstrate that vegetation growth is driven by groundwater access. Groundwater access conditions the rate of vegetation stabilization at the sub-reach scale and, due to a reduction in flood-related disturbance frequency over the last 50 years, drives a change in channel pattern. Where groundwater is shallower, vegetation encroachment rates were high and as flood-related disturbance decreased, the river has shifted towards a meandering state. Where groundwater was deeper, vegetation growth was limited by water-access and thus vegetation encroachment rates were low. Even though there was a reduction in flood disturbance, it was still sufficient to maintain a wandering/braided state. Thus, it appears that access to groundwater can control river channel pattern through its impact upon the "engineering effects" of vegetation. The results are important for river management as they highlight the non-linearity of developing vegetation in dynamic alluvial floodplains and the importance of considering the wider environmental setting and associated feedbacks between biotic and abiotic river components in defining long-term geomorphological river response.

Socio-demographic and lifestyle determinants of dietary patterns in French-speaking Switzerland, 2009-2012.

PubMed

Marques-Vidal, Pedro; Waeber, Gérard; Vollenweider, Peter; Guessous, Idris

2018-01-12

Food intake is a complex behaviour which can be assessed using dietary patterns. Our aim was to characterize dietary patterns and associated factors in French-speaking Switzerland. Cross-sectional study conducted between 2009 and 2012 in the city of Lausanne, Switzerland, including 4372 participants (54% women, 57.3 ± 10.3 years). Food consumption was assessed using a validated food frequency questionnaire. Dietary patterns were assessed by principal components analysis. Three patterns were identified: "Meat & fries"; "Fruits & Vegetables" and "Fatty & sugary". The "Meat & fries" pattern showed the strongest correlations with total and animal protein and cholesterol carbohydrates, dietary fibre and calcium. The "Fruits & Vegetables" pattern showed the strongest correlations with dietary fibre, carotene and vitamin D. The "Fatty & sugary" pattern showed the strongest correlations with total energy and saturated fat. On multivariate analysis, male gender, low educational level and sedentary status were positively associated with the "Meat & fries" and the "Fatty & sugary" patterns, and negatively associated with the "Fruits & Vegetables" pattern. Increasing age was inversely associated with the "Meat & fries" pattern; smoking status was inversely associated with the "Fruits & Vegetables" pattern. Being born in Portugal or Spain was positively associated with the "Meat & fries" and the "Fruits & Vegetables" patterns. Increasing body mass index was positively associated with the "Meat & fries" pattern and inversely associated with the "Fatty & sugary" pattern. Three dietary patterns, one healthy and two unhealthy, were identified in the Swiss population. Several associated modifiable behaviours were identified; the information on socio- demographic determinants allows targeting of the most vulnerable groups in the context of public health interventions.

The Role of River Morphodynamic Disturbance and Groundwater Hydrology As Driving Factors of Riparian Landscape Patterns in Mediterranean Rivers.

PubMed

Rivaes, Rui; Pinheiro, António N; Egger, Gregory; Ferreira, Teresa

2017-01-01

Fluvial disturbances, especially floods and droughts, are the main drivers of the successional patterns of riparian vegetation. Those disturbances control the riparian landscape dynamics through the direct interaction between flow and vegetation. The main aim of this work is to investigate the specific paths by which fluvial disturbances, distributed by its components of groundwater hydrology (grndh) and morphodynamic disturbance (mrphd), drive riparian landscape patterns as characterized by the location (position in the river corridor) and shape (physical form of the patch) of vegetation patches in Mediterranean rivers. Specifically, this work assesses how the different components of fluvial disturbances affect these features in general and particularly in each succession phase of riparian vegetation. grndh and mrphd were defined by time and intensity weighted indexes calculated, respectively, from the mean annual water table elevations and the annual maximum instantaneous discharge shear stresses of the previous decade. The interactions between riparian landscape features and fluvial disturbances were assessed by confirmatory factor analysis using structural equation modeling. Two hypothetical models for patch location and shape were conceptualized and tested against empirical data collected from 220 patches at four different study sites. Both models were successfully fitted, meaning that they adequately depicted the relationships between the variables. Furthermore, the models achieved a good adjustment for the observed data, based on the evaluation of several approximate fit indexes. The patch location model explained approximately 80% of the patch location variability, demonstrating that the location of the riparian patches is primarily driven by grndh, while the mrphd had very little effect on this feature. In a multigroup analysis regarding the succession phases of riparian vegetation, the fitted model explained more than 68% of the variance of the data, confirming the results of the general model. The patch shape model explained nearly 13% of the patch shape variability, in which the disturbances came to have less influence on driving this feature. However, grndh continues to be the primary driver of riparian vegetation between the two disturbance factors, despite the proportional increase of the mrphd effect to approximately a third of the grndh effect.

The Role of River Morphodynamic Disturbance and Groundwater Hydrology As Driving Factors of Riparian Landscape Patterns in Mediterranean Rivers

PubMed Central

Rivaes, Rui; Pinheiro, António N.; Egger, Gregory; Ferreira, Teresa

2017-01-01

Fluvial disturbances, especially floods and droughts, are the main drivers of the successional patterns of riparian vegetation. Those disturbances control the riparian landscape dynamics through the direct interaction between flow and vegetation. The main aim of this work is to investigate the specific paths by which fluvial disturbances, distributed by its components of groundwater hydrology (grndh) and morphodynamic disturbance (mrphd), drive riparian landscape patterns as characterized by the location (position in the river corridor) and shape (physical form of the patch) of vegetation patches in Mediterranean rivers. Specifically, this work assesses how the different components of fluvial disturbances affect these features in general and particularly in each succession phase of riparian vegetation. grndh and mrphd were defined by time and intensity weighted indexes calculated, respectively, from the mean annual water table elevations and the annual maximum instantaneous discharge shear stresses of the previous decade. The interactions between riparian landscape features and fluvial disturbances were assessed by confirmatory factor analysis using structural equation modeling. Two hypothetical models for patch location and shape were conceptualized and tested against empirical data collected from 220 patches at four different study sites. Both models were successfully fitted, meaning that they adequately depicted the relationships between the variables. Furthermore, the models achieved a good adjustment for the observed data, based on the evaluation of several approximate fit indexes. The patch location model explained approximately 80% of the patch location variability, demonstrating that the location of the riparian patches is primarily driven by grndh, while the mrphd had very little effect on this feature. In a multigroup analysis regarding the succession phases of riparian vegetation, the fitted model explained more than 68% of the variance of the data, confirming the results of the general model. The patch shape model explained nearly 13% of the patch shape variability, in which the disturbances came to have less influence on driving this feature. However, grndh continues to be the primary driver of riparian vegetation between the two disturbance factors, despite the proportional increase of the mrphd effect to approximately a third of the grndh effect. PMID:28979278

Estimating wetland vegetation abundance from Landsat-8 operational land imager imagery: a comparison between linear spectral mixture analysis and multinomial logit modeling methods

NASA Astrophysics Data System (ADS)

Zhang, Min; Gong, Zhaoning; Zhao, Wenji; Pu, Ruiliang; Liu, Ke

2016-01-01

Mapping vegetation abundance by using remote sensing data is an efficient means for detecting changes of an eco-environment. With Landsat-8 operational land imager (OLI) imagery acquired on July 31, 2013, both linear spectral mixture analysis (LSMA) and multinomial logit model (MNLM) methods were applied to estimate and assess the vegetation abundance in the Wild Duck Lake Wetland in Beijing, China. To improve mapping vegetation abundance and increase the number of endmembers in spectral mixture analysis, normalized difference vegetation index was extracted from OLI imagery along with the seven reflective bands of OLI data for estimating the vegetation abundance. Five endmembers were selected, which include terrestrial plants, aquatic plants, bare soil, high albedo, and low albedo. The vegetation abundance mapping results from Landsat OLI data were finally evaluated by utilizing a WorldView-2 multispectral imagery. Similar spatial patterns of vegetation abundance produced by both fully constrained LSMA algorithm and MNLM methods were observed: higher vegetation abundance levels were distributed in agricultural and riparian areas while lower levels in urban/built-up areas. The experimental results also indicate that the MNLM model outperformed the LSMA algorithm with smaller root mean square error (0.0152 versus 0.0252) and higher coefficient of determination (0.7856 versus 0.7214) as the MNLM model could handle the nonlinear reflection phenomenon better than the LSMA with mixed pixels.

Relationships among vegetation structure, canopy composition, and avian richness patterns across an aspen-conifer forest gradient

Treesearch

Charles E. Swift; Kerri T. Vierling; Andrew T. Hudak; Lee A. Vierling

2017-01-01

Ecologists have a long-term interest in understanding the relative influence of vegetation composition and vegetation structure on avian diversity. LiDAR remote sensing is useful in studying local patterns of avian diversity because it characterizes fine-scale vegetation structure across broad extents. We used LiDAR, aerial and satellite imagery, and avian field data...

Mountain pastures of Qilian Shan: plant communities, grazing impact and degradation status (Gansu province, NW China)

NASA Astrophysics Data System (ADS)

Baranova, Alina; Schickhoff, Udo; Shunli, Wang; Ming, Jin

2015-04-01

Qilian Mountains are the water source region for the low arid reaches of HeiHe river basin (Gansu province, NW China). Due to overstocking and overgrazing during the last decades adverse ecological ef¬fects, in particular on soil properties and hydrological cycle, are to be expected in growing land areas. Vegetation cover is very important to prevent erosion process and to sustain stable subsurface runoff and ground water flow. The aim of this research is to identify plant communities, detecting grazing-induced and spatially differentiated changes in vegetation patterns, and to evaluate status of pasture land degradation.The study area is located in the spring/autumn pasture area of South Qilian Mountains between 2600-3600 m a.s.l., covering five main vegetation types: spruce forest, alpine shrubland, shrubby grassland, mountain grassland, degraded mountain grassland. In order to analyze gradual changes in vegetation patterns along altitudinal and grazing gradients and to classify related plant communities, quantitative and qualitative relevé data were collected (coverage, species composition, abundance of unpalatable plants, plant functional types, etc.). Vegetation was classified using hierarchical cluster analyses. Indirect Detrended Correspondence Analysis (DCA) was used to analyze variation in relationships between vegetation, environmental factors, and grazing impact. According to DCA results, distribution of the plant communities was strongly affected by altitude and exposition. Grassland floristic gradients showed greater dependence on grazing impact, which correlated contrarily with soil organic content, soil moisture and pH. Highest numbers of species richness and alpha diversity were detected in alpine shrubland vegetation type. Comparing the monitoring data for the recent nine years, a trend of deterioration, species successions and shift in dominant species becomes obvious. Species indicating degrading site environmental conditions were identified. Most of the grasslands have become secondary vegetation, with a considerable percentage of unpalatable, toxic and often thorny or spiny shrub and herb species that have a lower grazing value and rarely form a closed vegetation cover, at least in loess slopes. To prevent further degradation of the grassland and to sustain the diversity of the plant species (affecting the carrying capacity pastureland) appropriate pasture management strategy should be implemented.

Topographically-controlled site conditions drive vegetation pattern on inland dunes in Poland

NASA Astrophysics Data System (ADS)

Sewerniak, Piotr; Jankowski, Michał

2017-07-01

The inland dunes of Central Europe are commonly overplanted by Scots pine (Pinus sylvestris) monocultures in which the primary occurrence of the natural vegetation pattern is obliterated. We hypothesize that on naturally revegetated inland dunes the pattern is clear and driven by topographically-controlled site conditions. To test this hypothesis, we addressed the following research questions: (1) Does topography drive vegetation patterns on inland dunes and if so, what are main differences between vegetation in varying relief positions? (2) To what extent does topography involve the variability of microclimates and of soil properties, and how does the topographically-induced differentiation of these site conditions control vegetation patterns? We conducted interdisciplinary studies (applying floristic, pedological and microclimatic research techniques) on a naturally revegetated inland dune area situated on a military artillery training ground near Toruń, northern Poland. We investigated vegetation patterns with reference to three topographical position variants (north-facing slopes, south-facing slopes, and intra-dune depressions). We found distinct differences in vegetation characteristics covering the aforementioned topographical positions. This primarily concerned species composition of ground vegetation: Calluna vulgaris was dominant species on north-facing slopes, Corynephorus canescens on south-facing slopes, while Calamagrostis epigejos in intra-dune depressions. In comparison to dune slopes, the depressions were characterized by much higher biodiversity of vascular plant species. This followed the most favorable soil conditions for the existence of plants (higher moisture and nutrient pools) occurring in low topographical positions. However, tree succession was most advanced not in depressions, where the competitive impact of tall grasses on seedlings was recognized, but on north-facing slopes. Based on our results, we formulated some suggestions, which could be useful for both practical foresters to increase biodiversity of ecosystems and for practices that work on the fixation of dunes by restoring vegetation.

Changes in vegetation and biological soil crust communities on sand dunes stabilizing after a century of grazing on San Miguel Island, Channel Island National Park, California

USGS Publications Warehouse

Zellman, Kristine L.

2014-01-01

San Miguel Island is the westernmost of the California Channel Islands and one of the windiest areas on the west coast of North America. The majority of the island is covered by coastal sand dunes, which were stripped of vegetation and subsequently mobilized due to droughts and sheep ranching during the late 19th century and early 20th century. Since the removal of grazing animals, vegetation and biological soil crusts have once again stabilized many of the island's dunes. In this study, historical aerial photographs and field surveys were used to develop a chronosequence of the pattern of change in vegetation communities and biological soil crust levels of development (LOD) along a gradient of dune stabilization. Historical aerial photographs from 1929, 1954, 1977, and 2009 were georeferenced and used to delineate changes in vegetation canopy cover and active (unvegetated) dune extent among 5 historical periods (pre-1929, 1929–1954, 1954–1977, 1977–2009, and 2009–2011). During fieldwork, vegetation and biological soil crust communities were mapped along transects distributed throughout San Miguel Island's central dune field on land forms that had stabilized during the 5 time periods of interest. Analyses in a geographic information system (GIS) quantified the pattern of changes that vegetation and biological soil crust communities have exhibited on the San Miguel Island dunes over the past 80 years. Results revealed that a continuing increase in total vegetation cover and a complex pattern of change in vegetation communities have taken place on the San Miguel Island dunes since the removal of grazing animals. The highly specialized native vascular vegetation (sea rocket, dunedelion, beach-bur, and locoweed) are the pioneer stabilizers of the dunes. This pioneer community is replaced in later stages by communities that are dominated by native shrubs (coastal goldenbush, silver lupine, coyote-brush, and giant coreopsis), with apparently overlapping or cyclical succession pathways. Many of the dunes that have been stabilized the longest (since before 1929) are dominated by exotic grasses. Stands of biological soil crusts (cyanobacteria) are found only on dunes where vascular vegetation is already present. Biological soil crusts are not found on dunes exhibiting a closed vascular plant canopy, which may indicate that the role of soil crusts in dune stabilization on the island is transitory. Particle-size analyses of soil samples from the study area reveal that higher biological soil crust LOD is positively correlated with increasing fine grain content. The findings indicate that changes in vegetation communities may be the most rapid at earlier and later stages of dune stabilization and that regular monitoring of dunes may help to identify the interactions between vegetation and soil crusts, as well as the potential transitions between native and exotic plant communities.

Carbon Storage in an Extensive Karst-distributed Region of Southwestern China based on Multiple Methods

NASA Astrophysics Data System (ADS)

Guo, C.; Wu, Y.; Yang, H.; Ni, J.

2015-12-01

Accurate estimation of carbon storage is crucial to better understand the processes of global and regional carbon cycles and to more precisely project ecological and economic scenarios for the future. Southwestern China has broadly and continuously distribution of karst landscapes with harsh and fragile habitats which might lead to rocky desertification, an ecological disaster which has significantly hindered vegetation succession and economic development in karst regions of southwestern China. In this study we evaluated the carbon storage in eight political divisions of southwestern China based on four methods: forest inventory, carbon density based on field investigations, CASA model driven by remote sensing data, and BIOME4/LPJ global vegetation models driven by climate data. The results show that: (1) The total vegetation carbon storage (including agricultural ecosystem) is 6763.97 Tg C based on the carbon density, and the soil organic carbon (SOC) storage (above 20cm depth) is 12475.72 Tg C. Sichuan Province (including Chongqing) possess the highest carbon storage in both vegetation and soil (1736.47 Tg C and 4056.56 Tg C, respectively) among the eight political divisions because of the higher carbon density and larger distribution area. The vegetation carbon storage in Hunan Province is the smallest (565.30 Tg C), and the smallest SOC storage (1127.40 Tg C) is in Guangdong Province; (2) Based on forest inventory data, the total aboveground carbon storage in the woody vegetation is 2103.29 Tg C. The carbon storage in Yunnan Province (819.01 Tg C) is significantly higher than other areas while tropical rainforests and seasonal forests in Yunnan contribute the maximum of the woody vegetation carbon storage (account for 62.40% of the total). (3) The net primary production (NPP) simulated by the CASA model is 68.57 Tg C/yr, while the forest NPP in the non-karst region (account for 72.50% of the total) is higher than that in the karst region. (4) BIOME4 and LPJ models predicted higher carbon storages than the CASA model with various spatial patterns. More investigations should be further performed to clarify processes of carbon cycle in ecosystems on karst terrain and to accelerate the development of a regional dynamic vegetation model which was appropriate for karst ecosystems.

A Methodology for Soil Moisture Retrieval from Land Surface Temperature, Vegetation Index, Topography and Soil Type

NASA Astrophysics Data System (ADS)

Pradhan, N. R.

2015-12-01

Soil moisture conditions have an impact upon hydrological processes, biological and biogeochemical processes, eco-hydrology, floods and droughts due to changing climate, near-surface atmospheric conditions and the partition of incoming solar and long-wave radiation between sensible and latent heat fluxes. Hence, soil moisture conditions virtually effect on all aspects of engineering / military engineering activities such as operational mobility, detection of landmines and unexploded ordinance, natural material penetration/excavation, peaking factor analysis in dam design etc. Like other natural systems, soil moisture pattern can vary from completely disorganized (disordered, random) to highly organized. To understand this varying soil moisture pattern, this research utilized topographic wetness index from digital elevation models (DEM) along with vegetation index from remotely sensed measurements in red and near-infrared bands, as well as land surface temperature (LST) in the thermal infrared bands. This research developed a methodology to relate a combined index from DEM, LST and vegetation index with the physical soil moisture properties of soil types and the degree of saturation. The advantage in using this relationship is twofold: first it retrieves soil moisture content at the scale of soil data resolution even though the derived indexes are in a coarse resolution, and secondly the derived soil moisture distribution represents both organized and disorganized patterns of actual soil moisture. The derived soil moisture is used in driving the hydrological model simulations of runoff, sediment and nutrients.

Plio-Pleistocene vegetation response on orbitally forced climatic cycles in Southern Europe - implications for early human environments

NASA Astrophysics Data System (ADS)

Bruch, Angela; Bertini, Adele

2013-04-01

The pace and causes of the early human colonization, in one or several migratory waves from Africa in new environments of the Eurasian continent during the Early Pleistocene, are still a matter of debate. However, climate change is considered a major driving factor of hominin evolution and dispersal patterns. In fact directly or indirectly by its severe influence on vegetation, physiography of landscape, and animal distribution, climate modulates the availability of resources. Plant fossils usually are rare or even absent at hominin sites. Thus, direct evidence on local vegetation and environment is generally missing. Independent from such localities, pollen profiles from the Mediterranean realm show the response of regional vegetation on global climate changes and cyclicity, with distinct spatial and temporal differences. Furthermore, plant fossils provide proxies for climate quantification that can be compared to the global signal, and add data to understanding the regional differentiation of Mediterranean environments. In this presentation we will discuss various palaeobotanical data from Southern Europe to assess Early Pleistocene climate and vegetation in time and space as part of the environment during the first expansions of early humans out of Africa.

Food environment of fruits and vegetables in the territory of the Health Academy Program.

PubMed

Costa, Bruna Vieira de Lima; Oliveira, Cláudia Di Lorenzo; Lopes, Aline Cristine Souza

2015-11-01

This study provides a spatial analysis of distribution and access to commercial fruit and vegetable establishments within the territory of a representative sample of public fitness facilities known as the Health Academy Program (HAP) in Belo Horizonte, Minas Gerais State, Brazil. The study evaluated commercial food establishments within a buffer area based on a radius of 1,600 meters around each of 18 randomly selected fitness facilities. Quality of access to fruits and vegetables was assessed by the Healthy Food Store Index (HFSI), consisting of the variables availability, variety, and advertising of fruits, vegetables and ultra-processed foods. The analysis was based on calculation of the Kernel intensity estimator, nearest neighbor method, and Ripley K-function. Of the 336 food establishments, 61.3% were green grocers and open-air markets, with a median HFSI of 11 (5 to 16). In only 17% of the territories, the majority of the "hot area" establishments displayed better access to healthy foods, and only three areas showed a clustering pattern. The study showed limited access to commercial establishments supplying healthy fruits and vegetables within the territory of the public fitness program.

Comparison of soil infiltration rates in burned and unburned mountainous watersheds

USGS Publications Warehouse

Martin, D.A.; Moody, J.A.

2001-01-01

Steady-state infiltration measurements were made at mountainous sites in New Mexico and Colorado, USA, with volcanic and granitic soils after wildfires and at comparable unburned sites. We measured infiltration in the New Mexico volcanic soils under two vegetation types, ponderosa pine and mixed conifer, and in the Colorado granitic soils under ponderosa pine vegetation. These measurements were made within high-severity burn areas using a portable infiltrometer with a 0.017 m2 infiltration area and artificial rainfall rates ranging from 97 to 440 mm h-1. Steady-state infiltration rates were less at all burned sites relative to unburned sites. The volcanic soil with ponderosa pine vegetation showed the greatest difference in infiltration rates with a ratio of steady-state infiltration rate in burned sites to unburned soils equal to 0.15. Volcanic soils with mixed conifer vegetation had a ratio (burned to unburned soils) of at most 0.38, and granitic soils with ponderosa pine vegetation had a ratio of 0.38. Steady-state infiltration rates on unburned volcanic and granitic soils with ponderosa pine vegetation are not statistically different. We present data on the particle-size distribution at all the study sites and examples of wetting patterns produced during the infiltration experiments. Published in 2001 by John Wiley and Sons, Ltd.

[Distribution patterns of wild felids (Carnivora: Felidae) in the dry tropics of Central-Western Mexico].

PubMed

Charre-Medellín, Juan Felipe; Monterrubio-Rico, Tiberio Cesar; Guido-Lemus, Daniel; Mendoza, Eduardo

2015-09-01

The Michoacán state is characterized by the existence of important environmental heterogeneity in terms of climate, topography and types of vegetation, which includes the worldwide endangered tropical dry forest. Some reports indicating the presence of the six species of felids occurring in Mexico in this region have been made; however, evidence to support these reports is scant, and filling this lack of information is particularly critical in the case of threatened species or habitats. The aim of this study was to systematize and analyze data distribution patterns of felids in the state of Michoacán, in the Central-Western Mexico. We conducted a review of literature and databases to compile species presence records in the study region. Moreover, we analyzed data obtained from ten years of field work conducted in the region, in which complementary methods (detection of direct and indirect evidence of species occurrence along transects, camera-trapping and interviews to local people) were applied to detect the presence of felid species. We compiled a total of 29 presence records of felids in the region from our review. Additionally, field work, which accumulated 1,107.5 km of walked transects, and 8 699 camera-trap days, produced 672 records of species presence. Lynx rufus was the species with the lowest number of records and the most restricted distribution. In contrast, the species with the greatest number of records was Leoparduspardalis (n = 343). In general, 89% of felids records occurred below 1,000 masl. Overall mean annual temperature of presence records was 24 °C and mean annual precipitation was 1,040 mm. The species whose presence records showed the most distinctive pattern, in terms of temperature and precipitation associated, was L. rufus (15.8 ± 1.3°C and 941 ± 171 mm). Results of a cluster analysis showed that areas supporting different combinations of eco-regions and types of vegetation could be grouped in five clusters having different assemblages of felid species and camera-trapping records. This study results useful to garner a more comprehensive view of the distribution patterns of felids in a region with important environmental contrasts and subjected to an increased human pressure. Moreover, this study provides insights that further our understanding of the relationship between environmental variables and felid distribution patterns which may have an impact for conservation and management strategies at the local and regional levels.

Species interactions and response time to climate change: ice-cover and terrestrial run-off shaping Arctic char and brown trout competitive asymmetries

NASA Astrophysics Data System (ADS)

Finstad, A. G.; Palm Helland, I.; Jonsson, B.; Forseth, T.; Foldvik, A.; Hessen, D. O.; Hendrichsen, D. K.; Berg, O. K.; Ulvan, E.; Ugedal, O.

2011-12-01

There has been a growing recognition that single species responses to climate change often mainly are driven by interaction with other organisms and single species studies therefore not are sufficient to recognize and project ecological climate change impacts. Here, we study how performance, relative abundance and the distribution of two common Arctic and sub-Arctic freshwater fishes (brown trout and Arctic char) are driven by competitive interactions. The interactions are modified both by direct climatic effects on temperature and ice-cover, and indirectly through climate forcing of terrestrial vegetation pattern and associated carbon and nutrient run-off. We first use laboratory studies to show that Arctic char, which is the world's most northernmost distributed freshwater fish, outperform trout under low light levels and also have comparable higher growth efficiency. Corresponding to this, a combination of time series and time-for-space analyses show that ice-cover duration and carbon and nutrient load mediated by catchment vegetation properties strongly affected the outcome of the competition and likely drive the species distribution pattern through competitive exclusion. In brief, while shorter ice-cover period and decreased carbon load favored brown trout, increased ice-cover period and increased carbon load favored Arctic char. Length of ice-covered period and export of allochthonous material from catchments are major, but contrasting, climatic drivers of competitive interaction between these two freshwater lake top-predators. While projected climate change lead to decreased ice-cover, corresponding increase in forest and shrub cover amplify carbon and nutrient run-off. Although a likely outcome of future Arctic and sub-arctic climate scenarios are retractions of the Arctic char distribution area caused by competitive exclusion, the main drivers will act on different time scales. While ice-cover will change instantaneously with increasing temperature, changes in catchment vegetation, such as forest-line or shrub advancement affecting carbon and nutrient transport into lakes, act on considerably longer time-scales. This study therefore emphasizes the recurring challenge for ecological climate change studies related to species interactions within and across ecosystem compartments and the response time of ecosystems.

[Research progress in water use efficiency of plants under global climate change].

PubMed

Wang, Qing-wei; Yu, Da-pao; Dai, Li-min; Zhou, Li; Zhou, Wang-ming; Qi, Guang; Qi, Lin; Ye, Yu-jing

2010-12-01

Global climate change is one of the most concerned environmental problems in the world since the 1980s, giving significant effects on the plant productivity and the water transport and use patterns. These effects would be reflected in the water use efficiency (WUE) of individual plants, communities, and ecosystems, and ultimately, in the vegetation distribution pattern, species composition, and ecosystem structure. To study the WUE of plants would help to the understanding and forecasting of the responses of terrestrial vegetation to global climate change, and to the adoption of adaptive strategies. This paper introduced the concept of plant WUE and the corresponding measurement techniques at the scales of leaf, individual plant, community, and ecosystem, and reviewed the research progress in the effects of important climatic factors such as elevated atmospheric CO2 concentration, precipitation pattern, nitrogen deposition, and their combination on the plant WUE, as well as the variation characteristics of plant WUE and the adaptive survival strategies of plants under different site conditions. Some problems related to plant WUE research were pointed out, and the future research directions in the context of global climate change were prospected.

Vegetation of the Elwha River estuary: Chapter 8 in Coastal habitats of the Elwha River, Washington--biological and physical patterns and processes prior to dam removal

USGS Publications Warehouse

Shafroth, Patrick B.; Fuentes, Tracy L.; Pritekel, Cynthia; Beirne, Matthew M.; Beauchamp, Vanessa B.; Duda, Jeffrey J.; Warrick, Jonathan A.; Magirl, Christopher S.

2011-01-01

The Elwha River estuary supports one of the most diverse coastal wetland complexes yet described in the Salish Sea region, in terms of vegetation types and plant species richness. Using a combination of aerial imagery and vegetation plot sampling, we identified 6 primary vegetation types and 121 plant species in a 39.7 ha area. Most of the estuary is dominated by woody vegetation types, with mixed riparian forest being the most abundant (20 ha), followed by riparian shrub (6.3 ha) and willow-alder forest (3.9 ha). The shrub-emergent marsh transition vegetation type was fourth most abundant (2.2 ha), followed by minor amounts of dunegrass (1.75 ha) and emergent marsh (0.2 ha). This chapter documents the abundance, distribution, and floristics of these six vegetation types, including plant species richness, life form, species origin (native or introduced), and species wetland indicator status. These data will serve as a baseline to which future changes can be compared, following the impending removal of Glines Canyon and Elwha Dams upstream on the Elwha River. Dam removals may alter many of the processes, materials, and biotic interactions that influence the estuary plant communities, including hydrology, salinity, sediment and wood transport, nutrients, and plant-microbe interactions.

Habitat segregation of Ambystoma gracile and Ambystoma macrodactylum in mountain ponds, Mount Rainer National Park, Washington, USA

USGS Publications Warehouse

Hoffman, Robert L.; Larson, Gary L.; Brokes, Brendan J.

2003-01-01

Ambystoma gracile (Baird) and Ambystoma macrodactylum Baird are common salamander species occupying key trophic positions in mountain ponds and lakes of Mount Rainier National Park (MORA). Based on amphibian surveys conducted in ponds and lakes in the northeast quadrant of MORA during the summers of 1993a??1995, 20 sites were resampled in 1996 to document and evaluate distributions of the two species relative to site habitat characteristics. Distributions of larvae were assessed either by nearshore snorkel or visual encounter surveys of each study site. Twelve environmental variables representing pond and lake physical characteristics, water quality, and nutrient concentrations were measured. The occurrences at each site of three major habitat components (i.e., pond bottom firmness, coarse woody debris, and emergent/aquatic vegetation) were qualitatively estimated. Allotopic distributions of larval populations of both species were related to site elevation, maximum depth, organic content of bottom substrates, and surface area. Ambystoma gracile sites were larger, deeper, lower in elevation, had flocculent sediment higher in organic content, abundant coarse woody debris, and limited emergent/aquatic vegetation relative to A. macrodactylum sites. Ambystoma macrodactylum sites were smaller, shallower, higher in elevation, had firm sediments low in organic content, and had a greater occurrence of emergent/aquatic vegetation than did A. gracile sites. Two sites supported syntopic populations and exhibited many of the habitat characteristics observed at sites inhabited by each species. The distribution of each species in MORA was related to the interconnection between habitat characteristics of ponds and lakes and species life-history patterns and possibly interspecific interactions.

Sexual differences in microhabitat selection of breeding little bustards Tetrax tetrax: Ecological segregation based on vegetation structure

NASA Astrophysics Data System (ADS)

Morales, M. B.; Traba, J.; Carriles, E.; Delgado, M. P.; de la Morena, E. L. García

2008-11-01

We examined sexual differences in patterns of vegetation structure selection in the sexually dimorphic little bustard. Differences in vegetation structure between male, female and non-used locations during reproduction were examined and used to build a presence/absence model for each sex. Ten variables were measured in each location, extracting two PCA factors (PC1: a visibility-shelter gradient; PC2: a gradient in food availability) used as response variables in GLM explanatory models. Both factors significantly differed between female, male and control locations. Neither study site nor phenology was significant. Logistic regression was used to model male and female presence/absence. Female presence was positively associated to cover of ground by vegetation litter, as well as overall vegetation cover, and negatively to vegetation density over 30 cm above ground. Male presence was positively related to litter cover and short vegetation and negatively to vegetation density over 30 cm above ground. Models showed good global performance and robustness. Female microhabitat selection and distribution seems to be related to the balance between shelter and visibility for surveillance. Male microhabitat selection would be related mainly to the need of conspicuousness for courtship. Accessibility to food resources seems to be equally important for both sexes. Differences suggest ecological sexual segregation resulting from different ecological constraints. These are the first detailed results on vegetation structure selection in both male and female little bustards, and are useful in designing management measures addressing vegetation structure irrespective of landscape composition. Similar microhabitat approaches can be applied to manage the habitat of many declining farmland birds.

Estimating plant available water content from remotely sensed evapotranspiration

NASA Astrophysics Data System (ADS)

van Dijk, A. I. J. M.; Warren, G.; Doody, T.

2012-04-01

Plant available water content (PAWC) is an emergent soil property that is a critical variable in hydrological modelling. PAWC determines the active soil water storage and, in water-limited environments, is the main cause of different ecohydrological behaviour between (deep-rooted) perennial vegetation and (shallow-rooted) seasonal vegetation. Conventionally, PAWC is estimated for a combination of soil and vegetation from three variables: maximum rooting depth and the volumetric water content at field capacity and permanent wilting point, respectively. Without elaborate local field observation, large uncertainties in PAWC occur due to the assumptions associated with each of the three variables. We developed an alternative, observation-based method to estimate PAWC from precipitation observations and CSIRO MODIS Reflectance-based Evapotranspiration (CMRSET) estimates. Processing steps include (1) removing residual systematic bias in the CMRSET estimates, (2) making spatially appropriate assumptions about local water inputs and surface runoff losses, (3) using mean seasonal patterns in precipitation and CMRSET to estimate the seasonal pattern in soil water storage changes, (4) from these, calculating the mean seasonal storage range, which can be treated as an estimate of PAWC. We evaluate the resulting PAWC estimates against those determined in field experiments for 180 sites across Australia. We show that the method produces better estimates of PAWC than conventional techniques. In addition, the method provides detailed information with full continental coverage at moderate resolution (250 m) scale. The resulting maps can be used to identify likely groundwater dependent ecosystems and to derive PAWC distributions for each combination of soil and vegetation type.

Take me to your leader: does early successional nonhost vegetation spatially inhibit Pissodes strobi (Coleoptera: Curculionidae)?

PubMed

Koopmans, Jordan M; De La Giroday, Honey-Marie C; Lindgren, B Staffan; Aukema, Brian H

2009-08-01

The spatial influences of host and nonhost trees and shrubs on the colonization patterns of white pine weevil Pissodes strobi (Peck) were studied within a stand of planted interior hybrid spruce [Picea glauca (Moench) Voss x Picea engelmannii (Parry) ex Engelm.]. Planted spruce accounted for one third of all trees within the stand, whereas the remaining two thirds were comprised of early-successional nonhost vegetation, such as alder (Alnus spp.), paper birch (Betula papyrifera Marsh.), black cottonwood [Populus balsamifera ssp. trichocarpa (T. Ng.) Brayshaw], lodgepole pine [Pinus contorta (Dougl.) ex Loud.], trembling aspen (Populus tremuloides Michx), willow (Salix spp.), and Canadian buffaloberry [Shepherdia canadensis (L.) Nutt.]. Unlike the spruce trees, nonhost vegetation in the stand was not uniformly distributed. Spatial point process models showed that Canadian buffaloberry, paper birch, black cottonwoood, and trembling aspen had negative associations with damage caused by the weevil, even though the density of the insects' hosts in these areas did not change. Moreover, knowing the locations of these nonhost trees provided as much, or more, inference about the locations of weevil-attacked trees as knowing the locations of suitable or preferred host trees (i.e., those larger in size). Nonhost volatiles, the alteration of soil composition, and overstory shade are discussed as potential explanatory factors for the patterns observed. New research avenues are suggested to determine whether nonhost vegetation in early successional stands might be an additional tool in the management of these insects in commercially important forests.

Bidirectional Reflectance Modeling of Non-homogeneous Plant Canopies

NASA Technical Reports Server (NTRS)

Norman, J. M. (Principal Investigator)

1985-01-01

The objective of this research is to develop a 3-dimensional radiative transfer model for predicting the bidirectional reflectance distribution function (BRDF) for heterogeneous vegetation canopies. The model (named BIGAR) considers the angular distribution of leaves, leaf area index, the location and size of individual subcanopies such as widely spaced rows or trees, spectral and directional properties of leaves, multiple scattering, solar position and sky condition, and characteristics of the soil. The model relates canopy biophysical attributes to down-looking radiation measurements for nadir and off-nadir viewing angles. Therefore, inversion of this model, which is difficult but practical should provide surface biophysical pattern; a fundamental goal of remote sensing. Such a model also will help to evaluate atmospheric limitations to satellite remote sensing by providing a good surface boundary condition for many different kinds of canopies. Furthermore, this model can relate estimates of nadir reflectance, which is approximated by most satellites, to hemispherical reflectance, which is necessary in the energy budget of vegetated surfaces.

Influence of local habitat features on disease avoidance by Caribbean spiny lobsters in a casita-enhanced bay.

PubMed

Briones-Fourzán, Patricia; Candia-Zulbarán, Rebeca I; Negrete-Soto, Fernando; Barradas-Ortiz, Cecilia; Huchin-Mian, Juan P; Lozano-Álvarez, Enrique

2012-08-27

In Bahía de la Ascensión, Mexico, 'casitas' (large artificial shelters) are extensively used to harvest Caribbean spiny lobsters Panulirus argus. After the discovery of a pathogenic virus, Panulirus argus virus 1 (PaV1), in these lobsters, laboratory experiments revealed that PaV1 could be transmitted by contact and through water, and that lobsters avoided shelters harboring diseased conspecifics. To examine these issues in the context of casitas, which typically harbor multiple lobsters of all sizes, we examined the distribution and aggregation patterns of lobsters in the absence/presence of diseased conspecifics (i.e. visibly infected with PaV1) in 531 casitas distributed over 3 bay zones, 1 poorly vegetated ('Vigía Chico', average depth: 1.5 m) and 2 more extensively vegetated ('Punta Allen': 2.5 m; 'Los Cayos': 2.4 m). All zones had relatively high indices of predation risk. Using several statistical approaches, we found that distribution parameters of lobsters were generally not affected by the presence of diseased conspecifics in casitas. Interestingly, however, in the shallower and less vegetated zone (Vigía Chico), individual casitas harbored more lobsters and lobsters were actually more crowded in casitas containing diseased conspecifics, yet disease prevalence was the lowest in lobsters of all sizes. These results suggest that (1) investment in disease avoidance by lobsters is partially modulated by local habitat features, (2) contact transmission rates of PaV1 may be lower in nature than in the laboratory, and (3) water-borne transmission rates may be lower in shallow, poorly vegetated habitats more exposed to solar ultraviolet radiation, which can damage viral particles.

[The contribution of L.G. Ramensky theoretical legacy to modern vegetation science (to the 130 anniversary of the scientist's birth)].

PubMed

Mirkin, B M; Naumova, L G

2015-01-01

L.G. Ramensky (1884-1953) was an outstanding Soviet geobotanist of the first part of XX century. Considered is his theoretical legacy and its contribution to modern vegetation science. L.G. Ramensky formulated the principle of vegetation continuum based on which the modern paradigm of vegetation science has been put into shape. The scientist made a contribution to the development of such important theoretical conceptions as types of plant strategy, coenosis and coenobiosis (coexistence of species), patterns of interannual variability in plant communities, ecological successions. The unique ecological scales were established by L.G. Ramensky that characterize the distribution of 1400 species over the gradients of soil moistening, richness, and salinization as well as moistening variability, pastoral digression, and alluvial intensity. He came out against mechanistic notions by V.N. Sukachev on a biogeocoenosis structure. The scientist did not offer his own method of plant communities classification but his well-reasoned criticism of dominant classification played a great role in adoption of floristical classification principles (Braun-Blanquet approach) by phytocenology in our country.

[Radioecological situation in the impact zone of the accidental underground nuclear explosion "Kraton-3" in the Republic of Sakha (Yakutia)].

PubMed

Sobakin, P I; Gerasimov, Ya R; Chevychelov, A P; Perk, A A; Goryachenkova, T A; Novikov, A P

2014-01-01

The paper reports on the results of a ground walking gamma- and gamma-spectrometric survey made in the impact zone of the accidental underground nuclear explosion "Kraton-3". Patterns of migration, 137Cs, 90Sr and Pu distribution in the soil-vegetable cover of the northern taiga on permafrost are considered. Radioeco- logical situation within the territory surveyed is noted as unfavorable.

Ecological study of peat landforms in Canada and Alaska

NASA Technical Reports Server (NTRS)

Glaser, Paul H.

1989-01-01

Over 20 percent of the land surface of Canada and Alaska is covered by peatlands, which may be defined as any waterlogged ecosystem with a minimum thickness of 20 cm of organic matter in the soil. Past investigations have demonstrated the value of aerial photographs in identifying the major vegetation types and analyzing the biotic and hydrogeologic processes that control the development of these peatlands. In the present study, LANDSAT TM imagery was used in conjunction with field studies to determine the utility of this satellite sensor for detecting these important processes. Although the vegetation landforms within these major peat basins are visible on aerial photographs, LANDSAT TM imagery provides essential new evidence for their analysis. Spectral data from the LANDSAT TM system provides: (1) synoptic views of the patterns across large portions of these peat basins, indicating important physiographic controls on peatland development, (2) more sensitive detection of the major vegetation types, allowing rapid quantitative estimates to be made of their distribution and aerial extent, (3) discrimination of bog areas with potentially rapid or slow rates of peat accumulation, (4) identification of discharge zones for groundwater, which apparently represents the most important source of alkalinity in these peat basins, and (5) detection of flow patterns in water tracks that appear nearly uniform on standard aerial photographs.

Dietary patterns and breast cancer risk in a prospective Japanese study.

PubMed

Kojima, Reiji; Okada, Emiko; Ukawa, Shigekazu; Mori, Mitsuru; Wakai, Kenji; Date, Chigusa; Iso, Hiroyasu; Tamakoshi, Akiko

2017-01-01

The association between dietary patterns and breast cancer has been inconsistent. This study examined associations between dietary patterns and risk of developing breast cancer among 23,172 women from the Japan Collaborative Cohort Study, including 119 incidences of breast cancer diagnosed during a median 16.9-year follow-up period. Factor analysis was conducted to obtain dietary patterns, and Cox proportional models were used to estimate hazard ratios (HR) and 95 % confidence intervals (95 % CI) for breast cancer morbidity. Three dietary patterns were identified: ''vegetable pattern'' (vegetables, potatoes, seaweed, tofu, fruits, fresh fish, eggs, and miso soup); ''animal food pattern'' (meat, deep-fried foods, fried vegetables, fish paste and salt-preserved fish); and "dairy product pattern'' (milk, dairy products, fruits, coffee and tea). After adjusting for potential confounders, the vegetable and dairy product patterns were not significantly associated with risk of breast cancer. However, the animal food pattern was significantly associated with a decreased risk of breast cancer morbidity among premenopausal women by HR 0.47 for the 2nd tertile (95 % CI 0.22-1.00) and HR 0.42 for the 3rd tertile (95 % CI 0.18-0.93), compared with the bottom tertile (p for trend 0.04). We found no significant association between the vegetable and dairy product dietary patterns and breast cancer risk; however, an animal product diet may reduce risk of breast cancer among premenopausal Japanese women.

Global linkages between teleconnection patterns and the terrestrial biosphere

NASA Astrophysics Data System (ADS)

Dahlin, Kyla M.; Ault, Toby R.

2018-07-01

Interannual variability in the global carbon cycle is largely due to variations in carbon uptake by terrestrial ecosystems, yet linkages between climate variability and variability in the terrestrial carbon cycle are not well understood at the global scale. Using a 30-year satellite record of semi-monthly leaf area index (LAI), we show that four modes of climate variability - El Niño/Southern Oscillation, the North Atlantic Oscillation, the Atlantic Meridional Mode, and the Indian Ocean Dipole Mode - strongly impact interannual vegetation growth patterns, with 68% of the land surface impacted by at least one of these teleconnection patterns, yet the spatial distribution of these impacts is heterogeneous. Considering the patterns' impacts by biome, none has an exclusively positive or negative relationship with LAI. Our findings imply that future changes in the frequency and/or magnitude of teleconnection patterns will lead to diverse changes to the terrestrial biosphere and the global carbon cycle.

Soil organic carbon - a large scale paired catchment assessment

NASA Astrophysics Data System (ADS)

Kunkel, V.; Hancock, G. R.; Wells, T.

2016-12-01

Soil organic carbon (SOC) concentration can vary both spatially and temporally driven by differences in soil properties, topography and climate. However most studies have focused on point scale data sets with a paucity of studies examining larger scale catchments. Here we examine the spatial and temporal distribution of SOC for two large catchments. The Krui (575 km2) and Merriwa River (675km2) catchments (New South Wales, Australia). Both have similar shape, soils, topography and orientation. We show that SOC distribution is very similar for both catchments and that elevation (and associated increase in soil moisture) is a major influence on SOC. We also show that there is little change in SOC from the initial assessment in 2006 to 2015 despite a major drought from 2003 to 2010 and extreme rainfall events in 2007 and 2010 -therefore SOC concentration appears robust. However, we found significant relationships between erosion and deposition patterns (as quantified using 137Cs) and SOC for both catchments again demonstrating a strong geomorphic relationship. Vegetation across the catchments was assessed using remote sensing (Landsat and MODIS). Vegetation patterns were temporally consistent with above ground biomass increasing with elevation. SOC could be predicted using both these low and high resolution remote sensing platforms. Results indicate that, although moderate resolution (250 m) allows for reasonable prediction of the spatial distribution of SOC, the higher resolution (30 m) improved the strength of the SOC-NDVI relationship. The relationship between SOC and 137Cs, as a surrogate for the erosion and deposition of SOC, suggested that sediment transport and deposition influences the distribution of SOC within the catchment. The findings demonstrate that over the large catchment scale and at the decadal time scale that SOC is relatively constant and can largely be predicted by topography.

Varying influence of environmental gradients on vegetation patterns across biomes

NASA Astrophysics Data System (ADS)

Dahlin, K.; Asner, G. P.; Mascaro, J.; Taylor, P.

2016-12-01

Environmental gradients, like elevation, slope, aspect, and soil properties, filter vegetation types at the local scale. These `environmental filters' create conditions that are conducive to the success or failure of different plant types, influencing landscape-scale heterogeneity in taxonomic diversity, functional diversity, biomass accumulation, greenness, and more. Niche-based models implicitly assume that environmental filtering is the dominant process controlling plant distributions. While environmental filtering is a well understood process, its importance relative to other drivers of heterogeneity, like disturbance, human impacts, and plant-animal interactions, remains unknown and likely varies between biomes. Here we synthesize results from several studies using data from the Carnegie Airborne Observatory - a fused LiDAR and imaging spectroscopy system - that mapped a vegetation patterns in multiple biomes and associated these with environmental gradients. The study sites range from Panama to California, and the patterns range from aboveground carbon to foliar chemistry. We show that at fine spatial scales environmental filtering is a strong predictor of aboveground biomass in a dry system (Jasper Ridge Biological Preserve, California - Dahlin et al 2012) but a weak predictor of plant functional traits in that same system (Dahlin et al 2014), a weak predictor of aboveground carbon in the tropics (Barro Colorado Island, Panama - Mascaro et al 2011; Osa Peninsula, Costa Rica - Taylor et al 2015), and a weak predictor of greenness (NDVI) in a disturbed dry system (Santa Cruz Island, California - Dahlin et al 2014). Collectively, these results suggest that while environmental filtering is an important driver of landscape-scale heterogeneity, it is not the only, or often even the most important, driver for many of these systems and patterns.

Arctic Tundra Vegetation Functional Types Based on Photosynthetic Physiology and Optical Properties

NASA Technical Reports Server (NTRS)

Huemmrich, Karl Fred; Gamon, John A.; Tweedie, Craig E.; Campbell, Petya K. Entcheva; Landis, David R.; Middleton, Elizabeth M.

2013-01-01

Non-vascular plants (lichens and mosses) are significant components of tundra landscapes and may respond to climate change differently from vascular plants affecting ecosystem carbon balance. Remote sensing provides critical tools for monitoring plant cover types, as optical signals provide a way to scale from plot measurements to regional estimates of biophysical properties, for which spatial-temporal patterns may be analyzed. Gas exchange measurements were collected for pure patches of key vegetation functional types (lichens, mosses, and vascular plants) in sedge tundra at Barrow, AK. These functional types were found to have three significantly different values of light use efficiency (LUE) with values of 0.013 plus or minus 0.0002, 0.0018 plus or minus 0.0002, and 0.0012 plus or minus 0.0001 mol C mol (exp -1) absorbed quanta for vascular plants, mosses and lichens, respectively. Discriminant analysis of the spectra reflectance of these patches identified five spectral bands that separated each of these vegetation functional types as well as nongreen material (bare soil, standing water, and dead leaves). These results were tested along a 100 m transect where midsummer spectral reflectance and vegetation coverage were measured at one meter intervals. Along the transect, area-averaged canopy LUE estimated from coverage fractions of the three functional types varied widely, even over short distances. The patch-level statistical discriminant functions applied to in situ hyperspectral reflectance data collected along the transect successfully unmixed cover fractions of the vegetation functional types. The unmixing functions, developed from the transect data, were applied to 30 m spatial resolution Earth Observing-1 Hyperion imaging spectrometer data to examine variability in distribution of the vegetation functional types for an area near Barrow, AK. Spatial variability of LUE was derived from the observed functional type distributions. Across this landscape, a fivefold variation in tundra LUE was observed. LUE calculated from the functional type cover fractions was also correlated to a spectral vegetation index developed to detect vegetation chlorophyll content. The concurrence of these alternate methods suggest that hyperspectral remote sensing can distinguish functionally distinct vegetation types and can be used to develop regional estimates of photosynthetic LUE in tundra landscapes.

Patterns of vegetation in the Owens Valley, California

NASA Technical Reports Server (NTRS)

Ustin, S. L.; Rock, B. N.; Woodward, R. A.

1986-01-01

Spectral characteristics of semi-arid shrub communities were examined using Airborne Imaging Spectrometer (AIS) data collected in the tree mode on 23 May 1985. Mesic sites with relatively high vegetation density and distinct zonation patterns exhibited greater spectral signature variations than sites with more xeric shrub communities. Spectral signature patterns were not directly related to vegetation density or physiognomy, although spatial maps derived from an 8-channel maximum likelihood classification were supported by photo-interpreted surface features. In AIS data, the principal detected effect of shrub vegetation on the alluvial fans is to lower reflectance across the spectrum. These results are similar to those reported during a period of minimal physiological activity in autumn, indicating that shadows cast by vegetation canopies are an important element of soil-vegetation interaction under conditions of relatively low canopy cover.

Spatial vegetation patterns and neighborhood competition among woody plants in an East African savanna

USDA-ARS?s Scientific Manuscript database

The majority of research on savanna vegetation dynamics has focused on the coexistence of woody and herbaceous vegetation; interactions among woody plants in savannas are relatively poorly understood. We present data from a 10-year longitudinal study of spatially explicit growth patterns of woody ve...

Predicting vegetation type through physiological and environmental interactions with leaf traits: evergreen and deciduous forests in an earth system modeling framework.

PubMed

Weng, Ensheng; Farrior, Caroline E; Dybzinski, Ray; Pacala, Stephen W

2017-06-01

Earth system models are incorporating plant trait diversity into their land components to better predict vegetation dynamics in a changing climate. However, extant plant trait distributions will not allow extrapolations to novel community assemblages in future climates, which will require a mechanistic understanding of the trade-offs that determine trait diversity. In this study, we show how physiological trade-offs involving leaf mass per unit area (LMA), leaf lifespan, leaf nitrogen, and leaf respiration may explain the distribution patterns of evergreen and deciduous trees in the temperate and boreal zones based on (1) an evolutionary analysis of a simple mathematical model and (2) simulation experiments of an individual-based dynamic vegetation model (i.e., LM3-PPA). The evolutionary analysis shows that these leaf traits set up a trade-off between carbon- and nitrogen-use efficiency at the scale of individual trees and therefore determine competitively dominant leaf strategies. As soil nitrogen availability increases, the dominant leaf strategy switches from one that is high in nitrogen-use efficiency to one that is high in carbon-use efficiency or, equivalently, from high-LMA/long-lived leaves (i.e., evergreen) to low-LMA/short-lived leaves (i.e., deciduous). In a region of intermediate soil nitrogen availability, the dominant leaf strategy may be either deciduous or evergreen depending on the initial conditions of plant trait abundance (i.e., founder controlled) due to feedbacks of leaf traits on soil nitrogen mineralization through litter quality. Simulated successional patterns by LM3-PPA from the leaf physiological trade-offs are consistent with observed successional dynamics of evergreen and deciduous forests at three sites spanning the temperate to boreal zones. © 2016 John Wiley & Sons Ltd.

Orographic influence on storm damage to forests in mountain areas by the example of windstorm 'Lothar'

NASA Astrophysics Data System (ADS)

Schmoeckel, J.; Kottmeier, Ch.

2003-04-01

The extraordinary strong storm 'LOTHAR' on December 26, 1999 caused large damage in the forests of France, Switzerland and Germany. In Germany, specially the Black Forest (Schwarzwald) was concerned. In this contribution an empirical analysis of storm damage in the northern Black Forest is given. The aim is to derive the orographical influence on the windfield from the damage pattern. This is recorded approx. 5 months after the desaster by an airborne survey with a digital line scanner. From these data highly resolved, georeferenced distributions of the vegetation index are calculated (2 m x 2 m pixel size). The damaged forest areas appear with a lower vegetation index than areas with intact vegetation. Demarcation between damaged forest areas and populated or differently used areas is given by a landuse model. Mapping of the storm damages and their combination with a digital elevation model and landuse data is performed in a GIS. It is shown that the damage pattern is significantly affected by orographic factors. Large damage occurred e.g. at the location of saddles between single mountains, on mountain flanks facing to the North and Northwest, and at the windward (west) flanks of extended mountain ridges. Little damage is found in areas that presumably were protected against the wind, i.e. on the leeside (eastern) mountain flanks, in dells and niches as well as in valleys perpendicular to the mean west to southwest winds. To explain the spatially complex distribution of damages more fully, an analysis is made where characteristics of the forest and of the soil are taken into account. The knowledge gained can be profitable for future afforestation in mountain areas to stabilize forests against severe storms.

Remote sensing-based characterization, 2-m, Plant Functional Type Distributions, Barrow Environmental Observatory, 2010

DOE Data Explorer

Langford, Zachary; Kumar, Jitendra; Hoffman, Forrest

2014-01-01

Arctic ecosystems have been observed to be warming faster than the global average and are predicted to experience accelerated changes in climate due to global warming. Arctic vegetation is particularly sensitive to warming conditions and likely to exhibit shifts in species composition, phenology and productivity under changing climate. Mapping and monitoring of changes in vegetation is essential to understand the effect of climate change on the ecosystem functions. Vegetation exhibits unique spectral characteristics which can be harnessed to discriminate plant types and develop quantitative vegetation indices. We have combined high resolution multi-spectral remote sensing from the WorldView 2 satellite with LIDAR-derived digital elevation models to characterize the tundra landscape on the North Slope of Alaska. Classification of landscape using spectral and topographic characteristics yields spatial regions with expectedly similar vegetation characteristics. A field campaign was conducted during peak growing season to collect vegetation harvests from a number of 1m x 1m plots in the study region, which were then analyzed for distribution of vegetation types in the plots. Statistical relationships were developed between spectral and topographic characteristics and vegetation type distributions at the vegetation plots. These derived relationships were employed to statistically upscale the vegetation distributions for the landscape based on spectral characteristics. Vegetation distributions developed are being used to provide Plant Functional Type (PFT) maps for use in the Community Land Model (CLM).

Asynchronous vegetation phenology enhances winter body condition of a large mobile herbivore.

PubMed

Searle, Kate R; Rice, Mindy B; Anderson, Charles R; Bishop, Chad; Hobbs, N T

2015-10-01

Understanding how spatial and temporal heterogeneity influence ecological processes forms a central challenge in ecology. Individual responses to heterogeneity shape population dynamics, therefore understanding these responses is central to sustainable population management. Emerging evidence has shown that herbivores track heterogeneity in nutritional quality of vegetation by responding to phenological differences in plants. We quantified the benefits mule deer (Odocoileus hemionus) accrue from accessing habitats with asynchronous plant phenology in northwest Colorado over 3 years. Our analysis examined both the direct physiological and indirect environmental effects of weather and vegetation phenology on mule deer winter body condition. We identified several important effects of annual weather patterns and topographical variables on vegetation phenology in the home ranges of mule deer. Crucially, temporal patterns of vegetation phenology were linked with differences in body condition, with deer tending to show poorer body condition in areas with less asynchronous vegetation green-up and later vegetation onset. The direct physiological effect of previous winter precipitation on mule deer body condition was much less important than the indirect effect mediated by vegetation phenology. Additionally, the influence of vegetation phenology on body fat was much stronger than that of overall vegetation productivity. In summary, changing annual weather patterns, particularly in relation to seasonal precipitation, have the potential to alter body condition of this important ungulate species during the critical winter period. This finding highlights the importance of maintaining large contiguous areas of spatially and temporally variable resources to allow animals to compensate behaviourally for changing climate-driven resource patterns.

Biogeographic distribution patterns and their correlates in the diverse frog fauna of the Atlantic Forest hotspot.

PubMed

Vasconcelos, Tiago S; Prado, Vitor H M; da Silva, Fernando R; Haddad, Célio F B

2014-01-01

Anurans are a highly diverse group in the Atlantic Forest hotspot (AF), yet distribution patterns and species richness gradients are not randomly distributed throughout the biome. Thus, we explore how anuran species are distributed in this complex and biodiverse hotspot, and hypothesize that this group can be distinguished by different cohesive regions. We used range maps of 497 species to obtain a presence/absence data grid, resolved to 50×50 km grain size, which was submitted to k-means clustering with v-fold cross-validation to determine the biogeographic regions. We also explored the extent to which current environmental variables, topography, and floristic structure of the AF are expected to identify the cluster patterns recognized by the k-means clustering. The biogeographic patterns found for amphibians are broadly congruent with ecoregions identified in the AF, but their edges, and sometimes the whole extent of some clusters, present much less resolved pattern compared to previous classification. We also identified that climate, topography, and vegetation structure of the AF explained a high percentage of variance of the cluster patterns identified, but the magnitude of the regression coefficients shifted regarding their importance in explaining the variance for each cluster. Specifically, we propose that the anuran fauna of the AF can be split into four biogeographic regions: a) less diverse and widely-ranged species that predominantly occur in the inland semideciduous forests; b) northern small-ranged species that presumably evolved within the Pleistocene forest refugia; c) highly diverse and small-ranged species from the southeastern Brazilian mountain chain and its adjacent semideciduous forest; and d) southern species from the Araucaria forest. Finally, the high congruence among the cluster patterns and previous eco-regions identified for the AF suggests that preserving the underlying habitat structure helps to preserve the historical and ecological signals that underlie the geographic distribution of AF anurans.

[Prediction of potential geographic distribution of Lyme disease in Qinghai province with Maximum Entropy model].

PubMed

Zhang, Lin; Hou, Xuexia; Liu, Huixin; Liu, Wei; Wan, Kanglin; Hao, Qin

2016-01-01

To predict the potential geographic distribution of Lyme disease in Qinghai by using Maximum Entropy model (MaxEnt). The sero-diagnosis data of Lyme disease in 6 counties (Huzhu, Zeku, Tongde, Datong, Qilian and Xunhua) and the environmental and anthropogenic data including altitude, human footprint, normalized difference vegetation index (NDVI) and temperature in Qinghai province since 1990 were collected. By using the data of Huzhu Zeku and Tongde, the prediction of potential distribution of Lyme disease in Qinghai was conducted with MaxEnt. The prediction results were compared with the human sero-prevalence of Lyme disease in Datong, Qilian and Xunhua counties in Qinghai. Three hot spots of Lyme disease were predicted in Qinghai, which were all in the east forest areas. Furthermore, the NDVI showed the most important role in the model prediction, followed by human footprint. Datong, Qilian and Xunhua counties were all in eastern Qinghai. Xunhua was in hot spot areaⅡ, Datong was close to the north of hot spot area Ⅲ, while Qilian with lowest sero-prevalence of Lyme disease was not in the hot spot areas. The data were well modeled in MaxEnt (Area Under Curve=0.980). The actual distribution of Lyme disease in Qinghai was in consistent with the results of the model prediction. MaxEnt could be used in predicting the potential distribution patterns of Lyme disease. The distribution of vegetation and the range and intensity of human activity might be related with Lyme disease distribution.

Using multi-scale sampling and spatial cross-correlation to investigate patterns of plant species richness

USGS Publications Warehouse

Kalkhan, M.A.; Stohlgren, T.J.

2000-01-01

Land managers need better techniques to assess exoticplant invasions. We used the cross-correlationstatistic, IYZ, to test for the presence ofspatial cross-correlation between pair-wisecombinations of soil characteristics, topographicvariables, plant species richness, and cover ofvascular plants in a 754 ha study site in RockyMountain National Park, Colorado, U.S.A. Using 25 largeplots (1000 m2) in five vegetation types, 8 of 12variables showed significant spatial cross-correlationwith at least one other variable, while 6 of 12variables showed significant spatial auto-correlation. Elevation and slope showed significant spatialcross-correlation with all variables except percentcover of native and exotic species. Percent cover ofnative species had significant spatialcross-correlations with soil variables, but not withexotic species. This was probably because of thepatchy distributions of vegetation types in the studyarea. At a finer resolution, using data from ten1 m2 subplots within each of the 1000 m2 plots, allvariables showed significant spatial auto- andcross-correlation. Large-plot sampling was moreaffected by topographic factors than speciesdistribution patterns, while with finer resolutionsampling, the opposite was true. However, thestatistically and biologically significant spatialcorrelation of native and exotic species could only bedetected with finer resolution sampling. We foundexotic plant species invading areas with high nativeplant richness and cover, and in fertile soils high innitrogen, silt, and clay. Spatial auto- andcross-correlation statistics, along with theintegration of remotely sensed data and geographicinformation systems, are powerful new tools forevaluating the patterns and distribution of native andexotic plant species in relation to landscape structure.

Terrestrial Feedbacks Incorporated in Global Vegetation Models through Observed Trait-Environment Responses

NASA Astrophysics Data System (ADS)

Bodegom, P. V.

2015-12-01

Most global vegetation models used to evaluate climate change impacts rely on plant functional types to describe vegetation responses to environmental stresses. In a traditional set-up in which vegetation characteristics are considered constant within a vegetation type, the possibility to implement and infer feedback mechanisms are limited as feedback mechanisms will likely involve a changing expression of community trait values. Based on community assembly concepts, we implemented functional trait-environment relationships into a global dynamic vegetation model to quantitatively assess this feature. For the current climate, a different global vegetation distribution was calculated with and without the inclusion of trait variation, emphasizing the importance of feedbacks -in interaction with competitive processes- for the prevailing global patterns. These trait-environmental responses do, however, not necessarily imply adaptive responses of vegetation to changing conditions and may locally lead to a faster turnover in vegetation upon climate change. Indeed, when running climate projections, simulations with trait variation did not yield a more stable or resilient vegetation than those without. Through the different feedback expressions, global and regional carbon and water fluxes were -however- strongly altered. At a global scale, model projections suggest an increased productivity and hence an increased carbon sink in the next decades to come, when including trait variation. However, by the end of the century, a reduced carbon sink is projected. This effect is due to a downregulation of photosynthesis rates, particularly in the tropical regions, even when accounting for CO2-fertilization effects. Altogether, the various global model simulations suggest the critical importance of including vegetation functional responses to changing environmental conditions to grasp terrestrial feedback mechanisms at global scales in the light of climate change.

A methodology for investigating interdependencies between measured throughfall, meteorological variables and canopy structure on a small catchment.

NASA Astrophysics Data System (ADS)

Maurer, Thomas; Gustavos Trujillo Siliézar, Carlos; Oeser, Anne; Pohle, Ina; Hinz, Christoph

2016-04-01

In evolving initial landscapes, vegetation development depends on a variety of feedback effects. One of the less understood feedback loops is the interaction between throughfall and plant canopy development. The amount of throughfall is governed by the characteristics of the vegetation canopy, whereas vegetation pattern evolution may in turn depend on the spatio-temporal distribution of throughfall. Meteorological factors that may influence throughfall, while at the same time interacting with the canopy, are e.g. wind speed, wind direction and rainfall intensity. Our objective is to investigate how throughfall, vegetation canopy and meteorological variables interact in an exemplary eco-hydrological system in its initial development phase, in which the canopy is very heterogeneous and rapidly changing. For that purpose, we developed a methodological approach combining field methods, raster image analysis and multivariate statistics. The research area for this study is the Hühnerwasser ('Chicken Creek') catchment in Lower Lusatia, Brandenburg, Germany, where after eight years of succession, the spatial distribution of plant species is highly heterogeneous, leading to increasingly differentiated throughfall patterns. The constructed 6-ha catchment offers ideal conditions for our study due to the rapidly changing vegetation structure and the availability of complementary monitoring data. Throughfall data were obtained by 50 tipping bucket rain gauges arranged in two transects and connected via a wireless sensor network that cover the predominant vegetation types on the catchment (locust copses, dense sallow thorn bushes and reeds, base herbaceous and medium-rise small-reed vegetation, and open areas covered by moss and lichens). The spatial configuration of the vegetation canopy for each measurement site was described via digital image analysis of hemispheric photographs of the canopy using the ArcGIS Spatial Analyst, GapLight and ImageJ software. Meteorological data from two on-site weather stations (wind direction, wind speed, air temperature, air humidity, insolation, soil temperature, precipitation) were provided by the 'Research Platform Chicken Creek' (https://www.tu-cottbus.de/projekte/en/oekosysteme/startseite.html). Data were combined and multivariate statistical analysis (PCA, cluster analysis, regression trees) were conducted using the R-software to i) obtain statistical indices describing the relevant characteristics of the data and ii) to identify the determining factors for throughfall intensity. The methodology is currently tested and results will be presented. Preliminary evaluation of the image analysis approach showed only marginal, systematic deviation of results for the different software tools applied, which makes the developed workflow a viable tool for canopy characterization. Results from this study will have a broad spectrum of possible applications, for instance the development / calibration of rainfall interception models, the incorporation into eco-hydrological models, or to test the fault tolerance of wireless rainfall sensor networks.

Factors controlling spatial distribution patterns of biocrusts in a heterogeneous and topographically complex semiarid area

NASA Astrophysics Data System (ADS)

Chamizo, Sonia; Rodríguez-Caballero, Emilio; Roncero, Beatriz; Raúl Román, José; Cantón, Yolanda

2016-04-01

Biocrusts are widespread soil components in drylands all over the world. They are known to play key roles in the functioning of these regions by fixing carbon and nitrogen, regulating hydrological processes, and preventing from water and wind erosion, thus reducing the loss of soil resources and increasing soil fertility. The rate and magnitude of services provided by biocrusts greatly depend on their composition and developmental stage. Late-successional biocrusts such as lichens and mosses have higher carbon and nitrogen fixation rates, and confer greater protection against erosion and the loss of sediments and nutrients than early-successional algae and cyanobacteria biocrusts. Knowledge of spatial distribution patterns of different biocrust types and the factors that control their distribution is important to assess ecosystem services provided by biocrusts at large spatial scales and to improve modelling of biogeochemical processes and water and carbon balance in drylands. Some of the factors that condition biocrust cover and composition are incoming solar radiation, terrain attributes, vegetation distribution patterns, microclimatic variables and soil properties such as soil pH, texture, soil organic matter, soil nutrients and gypsum and CaCO3 content. However, the factors that govern biocrust distribution may vary from one site to another depending on site characteristics. In this study, we examined the influence of abiotic attributes on the spatial distribution of biocrust types in a complex heterogeneous badland system (Tabernas, SE Spain) where biocrust cover up to 50% of the soil surface. From the analysis of relationships between terrain attributes and proportional abundance of biocrust types, it was found that topography exerted a main control on the spatial distribution of biocrust types in this area. SW-facing slopes were dominated by physical soil crusts and were practically devoid of vegetation and biocrusts. Biocrusts mainly occupied the pediments and NE-facing slopes. Cyanobacteria biocrusts were predominant in the pediments, probably because of their higher capacity to produce UV-protective pigments such as carotenoids and survive in zones of higher incident solar radiation. Lichen biocrusts showed preference for NE-facing slopes that, despite being less stable than the pediments, were exposed to less insolation and probably maintained moisture availability longer. Moreover, some differences were observed between lichen species. While Diploschistes diacapsis and Squamarina lentigera were widely distributed from gentle to steep NE-facing slopes, Lepraria sp. distribution was restricted to steep N-facing slopes, where shade predominance extended the periods of soil moisture availability.

The effect of vegetation patterns on wind-blown mass transport at the regional scale: A wind tunnel experiment

NASA Astrophysics Data System (ADS)

Youssef, Feras; Visser, Saskia M.; Karssenberg, Derek; Erpul, Gunay; Cornelis, Wim M.; Gabriels, Donald; Poortinga, Ate

2012-07-01

Wind erosion is a global environmental problem. Re-vegetating land is a commonly used method to reduce the negative effects of wind erosion. However, there is limited knowledge on the effect of vegetation pattern on wind-blown mass transport. The objective of this study was to investigate the effect of vegetation pattern on this phenomenon within a land unit and at the border between land units. Wind tunnel experiments were conducted with artificial shrubs representing Atriplex halimus. Wind runs at a speed of 11 m s- 1 were conducted and sand translocation was measured after 200-230 s using a graph paper prepared for this purpose. This research showed that: 1) the transport within a land unit is affected by the neighboring land units and by the vegetation pattern within both the unit itself and the neighboring land units; 2) re-vegetation plans for degraded land can take into account the 'streets' effect (zones of erosion areas similar to streets); 3) the effect of neighboring land units includes sheltering effect and the regulation of sediment passing from one land unit to the neighboring land units and 4) in addition to investigation of the general effect of vegetation pattern on erosion and deposition within the region, it is important to investigate the redistribution of sediment at smaller scales depending on the scope of the project.

Dietary pattern classifications with nutrient intake and health-risk factors in Korean men.

PubMed

Lee, Ji Eun; Kim, Jung-Hyun; Son, Say Jin; Ahn, Younjhin; Lee, Juyoung; Park, Chan; Lee, Lilha; Erickson, Kent L; Jung, In-Kyung

2011-01-01

This study was performed to identify dietary patterns in Korean men and to determine the associations among dietary patterns, nutrient intake, and health-risk factors. Using baseline data from the Korean Health and Genome Study, dietary patterns were identified using factor analysis of data from a validated food-frequency questionnaire, and associations between these dietary patterns and health-risk factors were analyzed. Three dietary patterns were identified: 1) the "animal-food" pattern (greater intake of meats, fish, and dairy products), 2) the "rice-vegetable" pattern (greater intake of rice, tofu, kimchi, soybean paste, vegetables, and seaweed), and 3) the "noodle-bread" pattern (greater intake of instant noodles, Chinese noodles, and bread). The animal-food pattern (preferred by younger people with higher income and education levels) had a positive correlation with obesity and hypercholesterolemia, whereas the rice-vegetable pattern (preferred by older people with lower income and educational levels) was positively associated with hypertension. The noodle-bread pattern (also preferred by younger people with higher income and education levels) had a positive association with abdominal obesity and hypercholesterolemia. This study identifies three unique dietary patterns in Korean men, which are independently associated with certain health-risk factors. The rice-vegetable dietary pattern, modified for a low sodium intake, might be a healthy dietary pattern for Korean men. Copyright © 2011 Elsevier Inc. All rights reserved.

A preliminary investigation of the variables affecting the distribution of giant gartersnakes (Thamnophis gigas) in the Sacramento Valley, California

USGS Publications Warehouse

Halstead, Brian J.; Skalos, Shannon M.; Casazza, Michael L.; Wylie, Glenn D.

2015-09-30

Giant gartersnakes (Thamnophis gigas) comprise a species of rare, semi-aquatic snake precinctive to the Central Valley of California. Because of the loss of more than 90% of their natural habitat, giant gartersnakes are listed as Threatened by the United States and California endangered species acts. Little is known, however, about the distribution of giant gartersnakes in the Sacramento Valley, which is where most extant populations occur. We conducted detection-nondetection surveys for giant gartersnakes throughout the rice-growing regions of the Sacramento Valley, and used occupancy models to examine evidence for the effects of landscape-scale GIS-derived variables, local habitat and vegetation composition, and prey communities on patterns of giant gartersnake occurrence. Although our results are based on a relatively small sample of sites, we found that distance to historic marsh, relative fish count, and an interaction of distance to historic marsh with proportion of habitat composed of submerged vegetation were important variables for explaining occupancy of giant gartersnakes. In particular, giant gartersnakes were more likely to occur closer to historic marsh and where relatively fewer fish were captured in traps. At locations in or near historic marsh, giant gartersnakes were more likely to occur in areas with less submerged vegetation, but this relationship was reversed (and more uncertain) at sites distant from historic marsh. Additional research with a larger sample of sites would further elucidate the distribution of giant gartersnakes in the Sacramento Valley.

Estimating live fuel status by drought indices: an approach for assessing local impact of climate change on fire danger

NASA Astrophysics Data System (ADS)

Pellizzaro, Grazia; Dubrovsky, Martin; Bortolu, Sara; Ventura, Andrea; Arca, Bachisio; Masia, Pierpaolo; Duce, Pierpaolo

2014-05-01

Mediterranean shrubs are an important component of both Mediterranean vegetation communities and understorey vegetation. They also constitute the surface fuels primarily responsible for the ignition and the spread of wildland fires in Mediterranean forests. Although fire spread and behaviour are dependent on several factors, the water content of live fuel plays an important role in determining fire occurrence and spread, especially in the Mediterranean shrubland, where live fuel is often the main component of the available fuel which catches fire. According to projections on future climate, an increase in risk of summer droughts is likely to take place in Southern Europe. More prolonged drought seasons induced by climatic changes are likely to influence general flammability characteristics of fuel, affecting load distribution in vegetation strata, floristic composition, and live and dead fuel ratio. In addition, variations in precipitation and mean temperature could directly affect fuel water status, and consequently flammability, and length of critical periods of high ignition danger for Mediterranean ecosystems. The main aim of this work was to propose a methodology for evaluating possible impacts of future climate change on moisture dynamic and length of fire danger period at local scale. Specific objectives were: i) evaluating performances of meteorological drought indices in describing seasonal pattern of live fuel moisture content (LFMC), and ii) simulating the potential impacts of future climate changes on the duration of fire danger period. Measurements of LFMC seasonal pattern of three Mediterranean shrub species were performed in North Western Sardinia (Italy) for 8 years. Seasonal patterns of LFMC were compared with the Drought Code of the Canadian Forest Fire Weather Index and the Keetch-Byram Drought Index. Analysis of frequency distribution and cumulative distribution curves were carried out in order to evaluate performance of codes and to identify threshold values of indices useful to determine the end of the potential fire season due to fuel status. A weather generator linked to climate change scenarios derived from 17 available General Circulation Models (GCMs) was used to produce synthetic weather series, representing present and future climates, for four selected sites located in North Sardinia, Italy. Finally, impacts of future climate change on fire season length at local scale were simulated. Results confirmed that the projected climate scenarios over the Mediterranean area will determine an overall increase of the fire season length.

Ecohydrologic Dynamics in Areas of Complex Topography in Semiarid Ecosystems

NASA Astrophysics Data System (ADS)

Ivanov, V. Y.; Bras, R. L.; Vivoni, E. R.

2008-12-01

Topography strongly affects the state and distribution of vegetation and this control is normally considered to operate through the regulation of the incoming solar radiation and lateral redistribution of water and elements. One of the areas of active research is how plants adjust to terrain effects relative to their location in a landscape and what the implications are for the spatial distribution of the water balance. This study emphasizes the coupled nature of interactions among vegetation-water-energy dynamics and their corresponding controls in complex topography of a semiarid ecosystem. These dynamics are investigated by constructing a coupled modeling system, tRIBS+VEGGIE, based on physical, biochemical, or mechanistic representation of individual processes. In a set of numerical experiments, linkages between terrain attributes, patterns of grass and shrub productivity, and water balance components are examined. For different imposed regimes of lateral water transfer, regions of relative vegetation "favorability" are identified. Their principal controlling mechanisms, as mediated by topographic features of the landscape, are investigated. It is argued that the long-term effects of site-specific and non-local terrain characteristics are superimposed and the key features of the superposition appear to be of the same form, irrespective of the soil hydraulic type or the actual water transport mechanism involved.

Evidence that local land use practices influence regional climate, vegetation, and stream flow patterns in adjacent natural areas

USGS Publications Warehouse

Stohlgren, T.J.; Chase, T.N.; Pielke, R.A.; Kittel, T.G.F.; Baron, Jill S.

1998-01-01

We present evidence that land use practices in the plains of Colorado influence regional climate and vegetation in adjacent natural areas in the Rocky Mountains in predictable ways. Mesoscale climate model simulations using the Colorado State University Regional Atmospheric Modelling System (RAMS) projected that modifications to natural vegetation in the plains, primarily due to agriculture and urbanization, could produce lower summer temperatures in the mountains. We corroborate the RAMS simulations with three independent sets of data: (i) climate records from 16 weather stations, which showed significant trends of decreasing July temperatures in recent decades; (ii) the distribution of seedlings of five dominant conifer species in Rocky Mountain National Park, Colorado, which suggested that cooler, wetter conditions occurred over roughly the same time period; and (iii) increased stream flow, normalized for changes in precipitation, during the summer months in four river basins, which also indicates cooler summer temperatures and lower transpiration at landscape scales. Combined, the mesoscale atmospheric/land-surface model, short-term in regional temperatures, forest distribution changes, and hydrology data indicate that the effects of land use practices on regional climate may overshadow larger-scale temperature changes commonly associated with observed increases in CO2 and other greenhouse gases.

Past and future effects of climate change on spatially heterogeneous vegetation activity in China

NASA Astrophysics Data System (ADS)

Gao, Jiangbo; Jiao, Kewei; Wu, Shaohong; Ma, Danyang; Zhao, Dongsheng; Yin, Yunhe; Dai, Erfu

2017-07-01

Climate change is a major driver of vegetation activity but its complex ecological relationships impede research efforts. In this study, the spatial distribution and dynamic characteristics of climate change effects on vegetation activity in China from the 1980s to the 2010s and from 2021 to 2050 were investigated using a geographically weighted regression (GWR) model. The GWR model was based on combined datasets of satellite vegetation index, climate observation and projection, and future vegetation productivity simulation. Our results revealed that the significantly positive precipitation-vegetation relationship was and will be mostly distributed in North China. However, the regions with temperature-dominated distribution of vegetation activity were and will be mainly located in South China. Due to the varying climate features and vegetation cover, the spatial correlation between vegetation activity and climate change may be altered. There will be different dominant climatic factors for vegetation activity distribution in some regions such as Northwest China, and even opposite correlations in Northeast China. Additionally, the response of vegetation activity to precipitation will move southward in the next three decades. In contrast, although the high warming rate will restrain the vegetation activity, precipitation variability could modify hydrothermal conditions for vegetation activity. This observation is exemplified in the projected future enhancement of vegetation activity in the Tibetan Plateau and weakened vegetation activity in East and Middle China. Furthermore, the vegetation in most parts of North China may adapt to an arid environment, whereas in many southern areas, vegetation will be repressed by water shortage in the future.

Using the Electromagnetic Induction Method to Connect Spatial Vegetation Distributions with Soil Water and Salinity Dynamics on Steppe Grassland

NASA Astrophysics Data System (ADS)

Jiang, Z.; Li, X.; Wu, H.

2014-12-01

In arid and semi-arid areas, plant growth and productivity are obviously affected by soil water and salinity. But it is not easy to acquire the spatial and temporal dynamics of soil water and salinity by traditional field methods because of the heterogeneity in their patterns. Electromagnetic induction (EMI), for its rapid character, can provide a useful way to solve this problem. Grassland dominated by Achnatherum splendens is an important ecosystem near the Qinghai-Lake watershed on the Qinghai-Tibet Plateau in northwestern China. EMI surveys were conducted for electrical conductivity (ECa) at an intermediate habitat scale (a 60×60 m experimental area) of A. splendens steppe for 18 times (one day only for one time) during the 2013 growing season. And twenty sampling points were established for the collection of soil samples for soil water and salinity, which were used for calibration of ECa. In addition, plant species, biomass and spatial patterns of vegetation were also sampled. The results showed that ECa maps exhibited distinctly spatial differences because of variations in soil moisture. And soil water was the main factor to drive salinity patterns, which in turn affected ECa values. Moreover, soil water and salinity could explain 82.8% of ECa changes due to there was a significant correlation (P<0.01) between ECa, soil water and salinity. Furthermore, with higher ECa values closer to A. splendens patches at the experimental site, patterns of ECa images showed clearly temporal stability, which were extremely corresponding with the spatial pattern of vegetation. A. splendens patches that accumulated infiltrating water and salinity and thus changed long-term soil properties, which were considered as "reservoirs" and were deemed responsible for the temporal stability of ECa images. Hence, EMI could be an indicator to locate areas of decreasing or increasing of water and to reveal soil water and salinity dynamics through repeated ECa surveys.

Lessons from the feeding infants and toddlers study in North America: what children eat, and implications for obesity prevention.

PubMed

Saavedra, Jose M; Deming, Denise; Dattilo, Anne; Reidy, Kathleen

2013-01-01

The latest exhaustive survey of dietary patterns in infants from the Feeding Infants and Toddlers Study (FITS) in North America documents and quantifies current trends in infant feeding. These include higher than generally recommended energy, protein, and saturated fat intakes. The majority of infants are bottle fed at some point in their first year of life, and their weaning diet often includes low intakes of fruits and vegetables, with high starchy, rather than green or yellow, vegetables. Early introduction of solids, use of cow's milk prior to 1 year of age, and high juice intake in the first 2 years - all less desirable diet practices - are improving, but are still prevalent. More preschoolers are likely to get sweets or sweetened beverages than a serving of fruit or a vegetable on a given day. These food intake patterns mimic the adult American diet and are associated with an increased risk of obesity in childhood and later life. But more importantly, these patterns appear to be set as early as 18 months of age, and by 20 months of age, they mimic the adult diet. Despite increase in total energy intake, and greater variety of foods, the basic characteristics of macronutrient intake distribution and food group contribution of energy to the diet before 2 years of age remain remarkably stable and similar to the family table. Obesity prevention needs to include specific targets in terms of breastfeeding and adequate formula feeding, as well as appropriate introduction of weaning foods with goals of changing the inadequate patterns documented in the FITS. These interventions will also require addressing parent and caregiver behaviors, including attending to hunger satiety cues (responsive feeding), and shaping early food preferences. This needs to be done starting at birth, in the first months of life. Early intervention offers a unique and potentially efficacious opportunity to shape the future dietary patterns of the next generation. Copyright © 2013 S. Karger AG, Basel.

Combining super-ensembles and statistical emulation to improve a regional climate and vegetation model

NASA Astrophysics Data System (ADS)

Hawkins, L. R.; Rupp, D. E.; Li, S.; Sarah, S.; McNeall, D. J.; Mote, P.; Betts, R. A.; Wallom, D.

2017-12-01

Changing regional patterns of surface temperature, precipitation, and humidity may cause ecosystem-scale changes in vegetation, altering the distribution of trees, shrubs, and grasses. A changing vegetation distribution, in turn, alters the albedo, latent heat flux, and carbon exchanged with the atmosphere with resulting feedbacks onto the regional climate. However, a wide range of earth-system processes that affect the carbon, energy, and hydrologic cycles occur at sub grid scales in climate models and must be parameterized. The appropriate parameter values in such parameterizations are often poorly constrained, leading to uncertainty in predictions of how the ecosystem will respond to changes in forcing. To better understand the sensitivity of regional climate to parameter selection and to improve regional climate and vegetation simulations, we used a large perturbed physics ensemble and a suite of statistical emulators. We dynamically downscaled a super-ensemble (multiple parameter sets and multiple initial conditions) of global climate simulations using a 25-km resolution regional climate model HadRM3p with the land-surface scheme MOSES2 and dynamic vegetation module TRIFFID. We simultaneously perturbed land surface parameters relating to the exchange of carbon, water, and energy between the land surface and atmosphere in a large super-ensemble of regional climate simulations over the western US. Statistical emulation was used as a computationally cost-effective tool to explore uncertainties in interactions. Regions of parameter space that did not satisfy observational constraints were eliminated and an ensemble of parameter sets that reduce regional biases and span a range of plausible interactions among earth system processes were selected. This study demonstrated that by combining super-ensemble simulations with statistical emulation, simulations of regional climate could be improved while simultaneously accounting for a range of plausible land-atmosphere feedback strengths.

Daily MODIS 500 m Reflectance Anisotropy Direct Broadcast (DB) Products for Monitoring Vegetation Phenology Dynamics

NASA Technical Reports Server (NTRS)

Shuai, Yanmin; Schaaf, Crystal; Zhang, Xiaoyang; Strahler, Alan; Roy, David; Morisette, Jeffrey; Wang, Zhuosen; Nightingale, Joanne; Nickeson, Jaime; Richardson, Andrew D.;

Investigation of n-Alkane Distributions in Modern Plant Litter from Hawaii wetlands: a potential proxy for past vegetation and hydroclimate changes?

NASA Astrophysics Data System (ADS)

Massa, C.; Beilman, D. W.; Nichols, J. E.; Elison Timm, O.

2016-12-01

Holocene peat deposits from the Hawaiian Islands provide a unique opportunity to resolve millennial to centennial-scale climate variability over the central Pacific region, where data remain scarce. Because both extratropical and tropical modes of climate variability have a strong influence on modern rainfall over the archipelago, hydroclimate proxies from peat would provide valuable information about past Pacific climate changes. The few terrestrial records studied, based on pollen or leaf wax biomarkers, showed evidence for substantial vegetation changes that have been linked to a drying trend over the Holocene. Leaf wax n-alkanes, as well as their stable isotopic compositions (δ13C and δD), are indeed increasingly used to reconstruct past hydroclimate conditions. The interpretation of n-alkanes as biomarkers requires however a thorough knowledge of their distribution in modern plants that contribute to sediments, but in Hawaii the modern vegetation is understudied compared to proxy applications. Here we report results from a preliminary investigation of n-alkanes distributions in dominant modern plant litter collected at a bog site at the summit of the Waianae mountains on the Island of Oahu. We compared n-alkane distributions among species and plant groups in order to test whether taxa or plant functional types (mosses, ferns, woody plants, and sedges) can be discriminated from their n-alkane profiles. Results showed that general plant groups were difficult to distinguish based on individual n-alkanes abundances, chain lengths, or ratios. At the species level, the sedge Machaerina augustifolia, was largely dominated by n-C29 ( 60%), suggesting some chain lengths could be useful as proxies for identifying the contribution of sedges to sedimentary records. Woody plant average chain length was highly variable but overall was not shorter (even slightly higher) than in other terrestrial plants, as it is often assumed. A sedimentary profile from this site shows variation and an overall decrease in n-alkane chain length over the Holocene, but patterns across common modern plants suggest that caution should be exercised when ascribing n-alkane distribution parameters to a specific group of tropical vegetation.

Severity of climate change dictates the direction of biophysical feedbacks of vegetation change to Arctic climate

NASA Astrophysics Data System (ADS)

Zhang, Wenxin; Jansson, Christer; Miller, Paul; Smith, Ben; Samuelsson, Patrick

2014-05-01

Vegetation-climate feedbacks induced by vegetation dynamics under climate change alter biophysical properties of the land surface that regulate energy and water exchange with the atmosphere. Simulations with Earth System Models applied at global scale suggest that the current warming in the Arctic has been amplified, with large contributions from positive feedbacks, dominated by the effect of reduced surface albedo as an increased distribution, cover and taller stature of trees and shrubs mask underlying snow, darkening the surface. However, these models generally employ simplified representation of vegetation dynamics and structure and a coarse grid resolution, overlooking local or regional scale details determined by diverse vegetation composition and landscape heterogeneity. In this study, we perform simulations using an advanced regional coupled vegetation-climate model (RCA-GUESS) applied at high resolution (0.44×0.44° ) over the Arctic Coordinated Regional Climate Downscaling Experiment (CORDEX-Arctic) domain. The climate component (RCA4) is forced with lateral boundary conditions from EC-EARTH CMIP5 simulations for three representative concentration pathways (RCP 2.6, 4.5, 8.5). Vegetation-climate response is simulated by the individual-based dynamic vegetation model (LPJ-GUESS), accounting for phenology, physiology, demography and resource competition of individual-based vegetation, and feeding variations of leaf area index and vegetative cover fraction back to the climate component, thereby adjusting surface properties and surface energy fluxes. The simulated 2m air temperature, precipitation, vegetation distribution and carbon budget for the present period has been evaluated in another paper. The purpose of this study is to elucidate the spatial and temporal characteristics of the biophysical feedbacks arising from vegetation shifts in response to different CO2 concentration pathways and their associated climate change. Our results indicate that the albedo feedback dominates simulated warming in spring in all three scenarios, while in summer, evapotranspiration feedback, governing the partitioning of the return energy flux from the surface to the atmosphere into latent and sensible heat, exerts evaporative cooling effects, the magnitude of which depends on the severity of climate change, in turn driven by the underlying GHG emissions pathway, resulting in shift in the sign of net biophysical at higher levels of warming. Spatially, western Siberia is identified as the most susceptible location, experiencing the potential to reverse biophysical feedbacks in all seasons. We further analyze how the pattern of vegetation shifts triggers different signs of net effects of biophysical feedbacks.

Drivers and feedbacks in spatial and temporal patterning of hydrology and vegetation in the Everglades wetlands

NASA Astrophysics Data System (ADS)

Miralles-Wilhelm, F.; Foti, R.; Rinaldo, A.; Rodriguez-Iturbe, I.; Del Jesus, M.

2013-05-01

Hosting a large variety of vegetal and animal species, many of which rare or endangered, wetlands are among the most rich and vulnerable ecosystems in the world. Throughout the past century, the growing climatic impact and the increasing anthropogenic pressure have seriously threatened their natural equilibrium and substantially deteriorated their ecosystems. For fragility, biodiversity and extension, the Everglades is probably one of the most iconic wetlands in the world. After decades of land seizing and exploitation following the southward march of development in Florida, awareness of the importance of the Everglades wetlands has recently risen, bringing it to the center of one of the largest and most ambitious restoration projects ever attempted. Wetlands equilibrium and biodiversity are crucially linked to the hydrologic regime. In the Everglades, hydroperiods (i.e. percent of time a site is inundated) exert a critical control in the creation of habitat niches for different plant species. However, the feedbacks between the hydrologic signature and the plant dynamics that ultimately yield the observed spatial vegetation patterns are unknown. We identify both the main hydrologic and local drivers of the vegetation species spatial configuration and use them within a robust modeling framework able to reproduce the vegetation structures currently observed in the Everglades. By including both exogenous (i.e. hydrologic) and endogenous (i.e. local interactions) forcings, we are able to describe the mechanisms yielding to the observed power law behavior of the cluster size distribution of vegetation species. Since power law clustering is often associated with self-organization and systems near critical transitions, these findings can be successfully used to quantitatively assess the impact of potential climatic shifts and the effect of habitat loss or deterioration due to human activity, and can assist policy makers in identifying case-specific ecosystems restoration and preservation measures.

Changing patterns of Pennsylvanian coal-swamp vegetation and implications of climatic control on coal occurrence

USGS Publications Warehouse

Phillips, T.L.; Peppers, R.A.

1984-01-01

Improved regional and interregional stratigraphic correlations of Pennsylvanian strata permit comparisons of vegetational changes in Euramerican coal swamps. The coal-swamp vegetation is known directly from in situ coal-ball peat deposits from more than 65 coals in the United States and Europe. Interpretations of coal-swamp floras on the basis of coal-ball peat studies are extended to broader regional and stratigraphic patterns by use of coal palynology. Objectives of the quantitative analyses of the vegetation in relation to coal are to determine the botanical constituents at the peat stage and their environmental implications for plant growth and peat accumulation. Morphological and paleoecological analyses provide a basis for deducing freshwater regimes of coal swamps. Changes in composition of Pennsylvanian coal-swamp vegetation are quire similar from one paralic coal region to another and show synchrony that is attributable to climate. Paleobotany and paleogeography of the Euramerican province indicate a moist tropical paleoclimate. Rainfall, runoff and evapotranspiration were the variable climatic controls in the distribution of coal-swamp vegetation, peat accumulation and coal resources. In relative terms of climatic wetness the Pennsylvanian Period is divisible into five intervals, which include two relatively drier intervals that developed during the Lower-Middle and Middle-Upper Pennsylvanian transitions. The climate during Early Pennsylvanian time was moderately wet and the median in moisture availability. Early Middle Pennsylvanian was drier, probably seasonally dry-wet; late Middle Pennsylvanian was the wettest in the Midcontinent; early Late Pennsylvanian was the driest; and late Late Pennsylvanian was probably the wettest in the Dunkard Basin. The five climatic intervals represent a general means of dividing coal resources within each region into groups with similar botanical constituents and environments of peat accumulation. Regional differences in basinal geology and climate were significant variables, but the synchronous control of paleoclimate was of primary importance. ?? 1984.

Spatial distribution of heavy metals in soil, water, and vegetables of farms in Sanandaj, Kurdistan, Iran.

PubMed

Maleki, Afshin; Amini, Hassan; Nazmara, Shahrokh; Zandi, Shiva; Mahvi, Amir Hossein

2014-01-01

Heavy metals are ubiquitous elsewhere in nature and their measurement in environment is necessary to develop health management strategies. In this study, we aimed to find out concentrations and spatial patterns of heavy metals in main farms of Sanandaj in Kurdistan, Iran. Over May to October 2012, six farms were selected to analyze concentrations and spatial patterns of several heavy metals, namely aluminum (Al), arsenic (As), cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), nickel (Ni), lead (Pb), and zinc (Zn) in their soil, irrigation water, and edible vegetables. Overall, 36 samples of soil and water and 72 samples of vegetables including coriander (Coriandrum sativum), dill (Anethum graveolens), radish (Raphanus sativus) root and radish leaf were collected. The concentrations of metals were determined by inductively coupled plasma optical emission spectrometry. The spatial surfaces of heavy metals were created using geospatial information system. The order of metals in soil was Al > Zn > Ni > Cu > Cr > Pb > Co > As > Cd while in water it was Cr > Co > Zn > Pb > Cu > Ni > Al = As = Cd. The order of heavy metals in vegetables was Al > Zn > Cu > Cr > Ni > Pb > Co > As > Cd. Totally, the minimum concentrations of Al, Cu, Pb, and Zn were found in radish root while the maximum of Al, Co, Cr, and Ni were found in radish leaf. The minimum concentrations of Cd and Cr and maximum concentrations of Cu and Zn were also deciphered in dill. Noteworthy, coriander had the minimum concentrations of Co and Ni. The concentrations of Cr and Pb in vegetables were more than maximum allowable limits of the Food and Agriculture Organization (FAO) and the World Health Organization (WHO). In summary, albeit the concentrations of heavy metals in soil and water samples were below FAO and the WHO standards, vegetables were contaminated by chromium and lead.

Plant Succession on the Mount St. Helen's Debris-Avalanche Deposit and the Role of Non-native Species

DOE Office of Scientific and Technical Information (OSTI.GOV)

Denton, Elsie M.; Dale, Virginia H.

The abstract is published online only. If you did not include a short abstract for the online version when you submitted the manuscript, the first paragraph or the first 10 lines of the chapter will be displayed here. If possible, please provide us with an informative abstract. The debris-avalanche deposit is one of the most disturbed areas created by the 1980 eruption of Mount St. Helens, with little survival of a few plant fragments and primary succession mostly being initiated by the seeds dispersed onto the newly emplaced material. Vegetation changes on the debris-avalanche deposit during the first 30 yearsmore » post eruption are analyzed considering the role of non-native species and potential future vegetation patterns on the deposit. We found that the aerial distribution of largely non-native seeds on a subset of plots at Mount St. Helens in 1980 has had a pronounced and enduring effect on subsequent vegetation communities.« less

The genus Anthia Weber in the Republic of South Africa, Identification, distribution, biogeography, and behavior (Coleoptera, Carabidae)

PubMed Central

Mawdsley, Jonathan R.; Erwin, Terry L.; Sithole, Hendrik; Mawdsley, James L.; Mawdsley, Alice S.

2011-01-01

Abstract A key is presented for the identification of the four species of Anthia Weber (Coleoptera: Carabidae) recorded from the Republic of South Africa: Anthia cinctipennis Lequien, Anthia circumscripta Klug, Anthia maxillosa (Fabricius), and Anthia thoracica (Thunberg). For each of these species, illustrations are provided of adult beetles of both sexes as well as illustrations of male reproductive structures, morphological redescriptions, discussions of morphological variation, annual activity histograms, and maps of occurrence localities in the Republic of South Africa. Maps of occurrence localities for these species are compared against ecoregional and vegetation maps of southern Africa; each species of Anthia shows a different pattern of occupancy across the suite of ecoregions and vegetation types in the Republic of South Africa. Information about predatory and foraging behaviors, Müllerian mimicry, and small-scale vegetation community associations is presented for Anthia thoracica based on field and laboratory studies in Kruger National Park, South Africa. PMID:22144866

Self-organized multi-species vegetation patterns: the role of connectivity of environmental niches in natural water harvesting ecosystems

NASA Astrophysics Data System (ADS)

Callegaro, Chiara; Ursino, Nadia

2016-04-01

Self-organizing vegetation patterns are natural water harvesting systems in arid and semi-arid regions of the world and should be imitated when designing man-managed water-harvesting systems for rain-fed crop. Disconnected vegetated and bare zones, functioning as a source-sink system of resources, sustain vegetation growth and reduce water and soil losses. Mechanisms such as soil crusting over bare areas and soil loosening in vegetated areas feed back to the local net facilitation effect and contribute to maintain the patterned landscape structure. Dis-connectivity of run-off production and run-on infiltration sites reduces runoff production at the landscape scale, and increases water retention in the vegetated patches. What is the effect of species adaptation to different resource niches on the landscape structure? A minimal model for two coexisting species and soil moisture balance was formulated, to improve our understanding of the effects of species differentiation on the dynamics of plants and water at single-pattern and landscape scale within a tiger bush type ecosystem. A basic assumption of our model was that soil moisture availability is a proxy for the environmental niche of plant species. Connectivity and dis-connectivity of specific niches of adaptation of two differing plant species was an input parameter of our model, in order to test the effect of coexistence on the ecosystem structure. The ecosystem structure is the model outcome, including: patterns persistence of coexisting species; patterns persistence of one species with exclusion of the other; patterns decline with just one species surviving in a non organized structure; bare landscape with loss of both species. Results suggest that pattern-forming-species communities arise as a result of complementary niche adaptation (niche dis-connecivity), whereas niche superposition (niche connectivity) may lead to impoverishment of environmental resources and loss of vegetation cover and diversity.

Co-evolution of Vegetation, Sediment Transport and Infiltration on semi-arid hillslopes

NASA Astrophysics Data System (ADS)

Harman, C. J.; Troch, P. A.; Lohse, K. A.; Sivapalan, M.

2011-12-01

Soils in semi-arid landscapes can vary over very small distances, with a great deal of variation associated with 'resource islands' created and maintained by woody vegetation. The distinct physical and hydraulic properties that arise in these islands can lead to spatial patterns of infiltration that have been implicated in the maintenance of the vegetation populating the island. Less well understood are the roles that the small-scale variability in soils plays in determining the transport of sediments, water and sediment-bound carbon and nitrogen across hillslopes. Here we explore these relationships using a coupled field and modeling approach. Detailed field data from hillslopes underlain by both granite and schist parent materials in the Santa Catalina mountains (part of the JSC Critical Zone Observatory) suggest that soils under individual velvet mesquite (latin name) contain higher concentration of soil organic matter and have higher hydraulic conductivity and water holding capacity. Greater infiltration and increased roughness under the canopy appears to lead to the formation of mounds that alter overland flow lines around the area under the canopy, particularly in the finer schist soils. This diversion leads to a complex distribution of shear stresses across the hillslope, creating systematic patterns in the transport of carbon and nitrogen rich soils under the canopies. The relationship between the small scale mechanism and the emergent pattern dynamics in the temporal variability of materials delivered to the stream from the hillslope are also examined, and the implications of these results for the modeling of water, sediment and nutrient fluxes at hillslope scales will be discussed.

Biological and climate factors co-regulated spatial-temporal dynamics of vegetation autumn phenology on the Tibetan Plateau

NASA Astrophysics Data System (ADS)

Zu, Jiaxing; Zhang, Yangjian; Huang, Ke; Liu, Yaojie; Chen, Ning; Cong, Nan

2018-07-01

Climate change is receiving mounting attentions from various fields and phenology is a commonly used indicator signaling vegetation responses to climate change. Previous phenology studies have mostly focused on vegetation greening-up and its climatic driving factors, while autumn phenology has been barely touched upon. In this study, vegetation phenological metrics were extracted from MODIS NDVI data and their temporal and spatial patterns were explored on the Tibetan Plateau (TP). The results showed that the start of season (SOS) has significantly earlier trend in the first decade, while the end of season (EOS) has slightly (not significant) earlier trend. In the spatial dimension, similar patterns were also identified. The SOS plays a more significant role in regulating vegetation growing season length than EOS does. The EOS and driving effects from each factor exhibited spatially heterogeneous patterns. Biological factor is the dominant factor regulating the spatial pattern of EOS, while climate factors control its inter-annual variation.

High-resolution pattern of mangrove species distribution is controlled by surface elevation

NASA Astrophysics Data System (ADS)

Leong, Rick C.; Friess, Daniel A.; Crase, Beth; Lee, Wei Kit; Webb, Edward L.

2018-03-01

Mangrove vegetation species respond to multiple environmental gradients, and an enhanced understanding of how mangrove species are distributed across these gradients will facilitate conservation and management. Many environmental gradients correlate with tidal inundation; however small-scale inundation patterns resulting from microtopographical changes are difficult to capture empirically. In contrast, surface elevation is often a suitable, measurable and cost-effective proxy for inundation. This study investigated the relationships between species distribution and surface elevation in a mangrove forest in northwest Singapore. Through high-resolution land surveying, we developed a digital elevation model (DEM) and conducted a comprehensive survey of 4380 trees with a stem diameter ≥ 5 cm. A total of 15 species were encountered, and elevation envelopes were generated for 12. Species envelopes were distributed along an elevation continuum, with most species overlapping within the continuum. Spatial autocorrelation (SAC) was present for nine of the 15 species, and when taken into account, species ordering was modified across the elevation continuum. The presence of SAC strongly reinforces the need for research to control for SAC: classical spatial description of mangrove species distribution should be revised to account for ecological factors. This study suggests that (1) surface elevation applies strong controls on species distribution and (2) most mangroves at our study site have similar physiological tolerances.

Spatial controls of occurrence and spread of wildfires in the Missouri Ozark Highlands.

PubMed

Yang, Jian; He, Hong S; Shifley, Stephen R

2008-07-01

Understanding spatial controls on wildfires is important when designing adaptive fire management plans and optimizing fuel treatment locations on a forest landscape. Previous research about this topic focused primarily on spatial controls for fire origin locations alone. Fire spread and behavior were largely overlooked. This paper contrasts the relative importance of biotic, abiotic, and anthropogenic constraints on the spatial pattern of fire occurrence with that on burn probability (i.e., the probability that fire will spread to a particular location). Spatial point pattern analysis and landscape succession fire model (LANDIS) were used to create maps to show the contrast. We quantified spatial controls on both fire occurrence and fire spread in the Midwest Ozark Highlands region, USA. This area exhibits a typical anthropogenic surface fire regime. We found that (1) human accessibility and land ownership were primary limiting factors in shaping clustered fire origin locations; (2) vegetation and topography had a negligible influence on fire occurrence in this anthropogenic regime; (3) burn probability was higher in grassland and open woodland than in closed-canopy forest, even though fire occurrence density was less in these vegetation types; and (4) biotic and abiotic factors were secondary descriptive ingredients for determining the spatial patterns of burn probability. This study demonstrates how fire occurrence and spread interact with landscape patterns to affect the spatial distribution of wildfire risk. The application of spatial point pattern data analysis would also be valuable to researchers working on landscape forest fire models to integrate historical ignition location patterns in fire simulation.

Root Water Uptake and Soil Moisture Pattern Dynamics - Capturing Connections, Controls and Causalities

NASA Astrophysics Data System (ADS)

Blume, T.; Heidbuechel, I.; Hassler, S. K.; Simard, S.; Guntner, A.; Stewart, R. D.; Weiler, M.

2015-12-01

We hypothesize that there is a shift in controls on landscape scale soil moisture patterns when plants become active during the growing season. Especially during the summer soil moisture patterns are not only controlled by soils, topography and related abiotic site characteristics but also by root water uptake. Root water uptake influences soil moisture patterns both in the lateral and vertical direction. Plant water uptake from different soil depths is estimated based on diurnal fluctuations in soil moisture content and was investigated with a unique setup of 46 field sites in Luxemburg and 15 field sites in Germany. These sites cover a range of geologies, soils, topographic positions and types of vegetation. Vegetation types include pasture, pine forest (young and old) and different deciduous forest stands. Available data at all sites includes information at high temporal resolution from 3-5 soil moisture and soil temperature profiles, matrix potential, piezometers and sapflow sensors as well as standard climate data. At sites with access to a stream, discharge or water level is also recorded. The analysis of soil moisture patterns over time indicates a shift in regime depending on season. Depth profiles of root water uptake show strong differences between different forest stands, with maximum depths ranging between 50 and 200 cm. Temporal dynamics of signal strength within the profile furthermore suggest a locally shifting spatial distribution of root water uptake depending on water availability. We will investigate temporal thresholds (under which conditions spatial patterns of root water uptake become most distinct) as well as landscape controls on soil moisture and root water uptake dynamics.

Using a spatially-distributed hydrologic biogeochemistry model to study the spatial variation of carbon processes in a Critical Zone Observatory

NASA Astrophysics Data System (ADS)

Shi, Y.; Eissenstat, D. M.; Davis, K. J.; He, Y.

2016-12-01

Forest carbon processes are affected by, among other factors, soil moisture, soil temperature, soil nutrients and solar radiation. Most of the current biogeochemical models are 1-D and represent one point in space. Therefore, they cannot resolve the topographically driven hill-slope land surface heterogeneity or the spatial pattern of nutrient availability. A spatially distributed forest ecosystem model, Flux-PIHM-BGC, has been developed by coupling a 1-D mechanistic biogeochemical model Biome-BGC (BBGC) with a spatially distributed land surface hydrologic model, Flux-PIHM. Flux-PIHM is a coupled physically based model, which incorporates a land-surface scheme into the Penn State Integrated Hydrologic Model (PIHM). The land surface scheme is adapted from the Noah land surface model. Flux-PIHM is able to represent the link between groundwater and the surface energy balance, as well as the land surface heterogeneities caused by topography. In the coupled Flux-PIHM-BGC model, each Flux-PIHM model grid couples a 1-D BBGC model, while soil nitrogen is transported among model grids via subsurface water flow. In each grid, Flux-PIHM provides BBGC with soil moisture, soil temperature, and solar radiation information, while BBGC provides Flux-PIHM with leaf area index. The coupled Flux-PIHM-BGC model has been implemented at the Susquehanna/Shale Hills critical zone observatory (SSHCZO). Model results suggest that the vegetation and soil carbon distribution is primarily constrained by nitorgen availability (affected by nitorgen transport via topographically driven subsurface flow), and also constrained by solar radiation and root zone soil moisture. The predicted vegetation and soil carbon distribution generally agrees with the macro pattern observed within the watershed. The coupled ecosystem-hydrologic model provides an important tool to study the impact of topography on watershed carbon processes, as well as the impact of climate change on water resources.

[Effects of road construction on regional vegetation types].

PubMed

Liu, Shi-Liang; Liu, Qi; Wang, Cong; Yang, Jue-Jie; Deng, Li

2013-05-01

As a regional artificial disturbance component, road exerts great effects on vegetation types, and plays a substantial role in defining vegetation distribution to a certain extent. Aiming at the tropical rainforest degradation and artificial forest expansion in Yunnan Province of Southwest China, this paper analyzed the effects of road network extension on regional vegetation types. In the Province, different classes of roads had different effects on the vegetation types, but no obvious regularity was observed in the effects on the patch areas of different vegetation types due to the great variations of road length and affected distance. However, the vegetation patch number was more affected by lower class roads because of their wide distribution. As for different vegetation types, the vegetations on cultivated land were most affected by roads, followed by Castanopsis hystrix and Schima wallichii forests. Road network formation contributed most to the vegetation fragmentation, and there existed significant correlations between the human disturbance factors including village- and road distributions.

Evaluating the Spatial Distribution of Toxic Air Contaminants in Multiple Ecosystem Indicators in the Sierra Nevada-Southern Cascades

NASA Astrophysics Data System (ADS)

Nanus, L.; Simonich, S. L.; Rocchio, J.; Flanagan, C.

2013-12-01

Toxic air contaminants originating from agricultural areas of the Central Valley in California threaten vulnerable sensitive receptors including surface water, vegetation, snow, sediments, fish, and amphibians in the Sierra Nevada-Southern Cascades region. The spatial distribution of toxic air contaminants in different ecosystem indicators depends on variation in atmospheric concentrations and deposition, and variation in air toxics accumulation in ecosystems. The spatial distribution of organic air toxics and mercury at over 330 unique sampling locations and sample types over two decades (1990-2009) in the Sierra Nevada-Southern Cascades region were compiled and maps were developed to further understand spatial patterns and linkages between air toxics deposition and ecological effects. Potential ecosystem impacts in the Sierra Nevada-Southern Cascades region include bioaccumulation of air toxics in both aquatic and terrestrial ecosystems, reproductive disruption, and immune suppression. The most sensitive ecological end points in the region that are affected by bioaccumulation of toxic air contaminants are fish. Mercury was detected in all fish and approximately 6% exceeded human consumption thresholds. Organic air toxics were also detected in fish yielding variable spatial patterns. For amphibians, which are sensitive to pesticide exposure and potential immune suppression, increasing trends in current and historic use pesticides are observed from north to south across the region. In other indicators, such as vegetation, pesticide concentrations in lichen increase with increasing elevation. Current and historic use pesticides and mercury were also observed in snowpack at high elevations in the study area. This study shows spatial patterns in toxic air contaminants, evaluates associated risks to sensitive receptors, and identifies data gaps. Future research on atmospheric modeling and information on sources is needed in order to predict which ecosystems are the most sensitive to toxic air contaminants in the Sierra Nevada-Southern Cascades region.

Carbon Inputs From Riparian Vegetation Limit Oxidation of Physically Bound Organic Carbon Via Biochemical and Thermodynamic Processes

NASA Astrophysics Data System (ADS)

Graham, Emily B.; Tfaily, Malak M.; Crump, Alex R.; Goldman, Amy E.; Bramer, Lisa M.; Arntzen, Evan; Romero, Elvira; Resch, C. Tom; Kennedy, David W.; Stegen, James C.

2017-12-01

In light of increasing terrestrial carbon (C) transport across aquatic boundaries, the mechanisms governing organic carbon (OC) oxidation along terrestrial-aquatic interfaces are crucial to future climate predictions. Here we investigate the biochemistry, metabolic pathways, and thermodynamics corresponding to OC oxidation in the Columbia River corridor using ultrahigh-resolution C characterization. We leverage natural vegetative differences to encompass variation in terrestrial C inputs. Our results suggest that decreases in terrestrial C deposition associated with diminished riparian vegetation induce oxidation of physically bound OC. We also find that contrasting metabolic pathways oxidize OC in the presence and absence of vegetation and—in direct conflict with the "priming" concept—that inputs of water-soluble and thermodynamically favorable terrestrial OC protect bound-OC from oxidation. In both environments, the most thermodynamically favorable compounds appear to be preferentially oxidized regardless of which OC pool microbiomes metabolize. In turn, we suggest that the extent of riparian vegetation causes sediment microbiomes to locally adapt to oxidize a particular pool of OC but that common thermodynamic principles govern the oxidation of each pool (i.e., water-soluble or physically bound). Finally, we propose a mechanistic conceptualization of OC oxidation along terrestrial-aquatic interfaces that can be used to model heterogeneous patterns of OC loss under changing land cover distributions.

Palynology after Y2K--Understanding the Source Area of Pollen in Sediments

NASA Astrophysics Data System (ADS)

Davis, M. B.

Pollen grains preserved in lake and bog sediment provide a record of past vegetation that has been an important source of information about climate and land cover during the Quaternary Period. Yet from the beginning, questions have been raised about the source area of pollen in sediment. Interpretation has been hampered by the lack of well-developed theory treating the relationship between the spatial distribution of trees on the landscape and the percentages of pollen in sediment. Within the past decade, however, new theory, models, and empirical data show how heterogeneous vegetation is represented by pollen. The distinction between "local" and "regional" pollen is explained by the Prentice-Sugita dispersal/deposition models, which predict how the ratio of regional to local pollen changes with lake size. Sugita's model simulating a landscape with heterogeneous vegetation predicts the size of the relevant source area-the area of vegetation reflected in between-lake variations in pollen loading-while demonstrating that regional pollen from beyond this distance is homogeneous at all lakes of similar size. By predicting the way landscape patterns will be reflected in pollen records, simulation models can improve research design and lead to more detailed and spatially precise records of past vegetation, enhancing continental-scale climate reconstructions.

Ecological-niche modeling and prioritization of conservation-area networks for Mexican herpetofauna.

PubMed

Urbina-Cardona, J Nicolás; Flores-Villela, Oscar

2010-08-01

One of the most important tools in conservation biology is information on the geographic distribution of species and the variables determining those patterns. We used maximum-entropy niche modeling to run distribution models for 222 amphibian and 371 reptile species (49% endemics and 27% threatened) for which we had 34,619 single geographic records. The planning region is in southeastern Mexico, is 20% of the country's area, includes 80% of the country's herpetofauna, and lacks an adequate protected-area system. We used probabilistic data to build distribution models of herpetofauna for use in prioritizing conservation areas for three target groups (all species and threatened and endemic species). The accuracy of species-distribution models was better for endemic and threatened species than it was for all species. Forty-seven percent of the region has been deforested and additional conservation areas with 13.7% to 88.6% more native vegetation (76% to 96% of the areas are outside the current protected-area system) are needed. There was overlap in 26 of the main selected areas in the conservation-area network prioritized to preserve the target groups, and for all three target groups the proportion of vegetation types needed for their conservation was constant: 30% pine and oak forests, 22% tropical evergreen forest, 17% low deciduous forest, and 8% montane cloud forests. The fact that different groups of species require the same proportion of habitat types suggests that the pine and oak forests support the highest proportion of endemic and threatened species and should therefore be given priority over other types of vegetation for inclusion in the protected areas of southeastern Mexico.

The vegetation outlook (VegOut): a new method for predicting vegetation seasonal greenness

USGS Publications Warehouse

Tadesse, T.; Wardlow, B.; Hayes, M.; Svoboda, M.; Brown, J.

2010-01-01

The vegetation outlook (VegOut) is a geospatial tool for predicting general vegetation condition patterns across large areas. VegOut predicts a standardized seasonal greenness (SSG) measure, which represents a general indicator of relative vegetation health. VegOut predicts SSG values at multiple time steps (two to six weeks into the future) based on the analysis of "historical patterns" (i.e., patterns at each 1 km grid cell and time of the year) of satellite, climate, and oceanic data over an 18-year period (1989 to 2006). The model underlying VegOut capitalizes on historical climate-vegetation interactions and ocean-climate teleconnections (such as El Niño and the Southern Oscillation, ENSO) expressed over the 18-year data record and also considers several environmental characteristics (e.g., land use/cover type and soils) that influence vegetation's response to weather conditions to produce 1 km maps that depict future general vegetation conditions. VegOut provides regionallevel vegetation monitoring capabilities with local-scale information (e.g., county to sub-county level) that can complement more traditional remote sensing-based approaches that monitor "current" vegetation conditions. In this paper, the VegOut approach is discussed and a case study over the central United States for selected periods of the 2008 growing season is presented to demonstrate the potential of this new tool for assessing and predicting vegetation conditions.

Evaluation of the New Dynamic Global Vegetation Model in CAS-ESM

NASA Astrophysics Data System (ADS)

Zhu, Jiawen; Zeng, Xiaodong; Zhang, Minghua; Dai, Yongjiu; Ji, Duoying; Li, Fang; Zhang, Qian; Zhang, He; Song, Xiang

2018-06-01

In the past several decades, dynamic global vegetation models (DGVMs) have been the most widely used and appropriate tool at the global scale to investigate vegetation-climate interactions. At the Institute of Atmospheric Physics, a new version of DGVM (IAP-DGVM) has been developed and coupled to the Common Land Model (CoLM) within the framework of the Chinese Academy of Sciences' Earth System Model (CAS-ESM). This work reports the performance of IAP-DGVM through comparisons with that of the default DGVM of CoLM (CoLM-DGVM) and observations. With respect to CoLMDGVM, IAP-DGVM simulated fewer tropical trees, more "needleleaf evergreen boreal tree" and "broadleaf deciduous boreal shrub", and a better representation of grasses. These contributed to a more realistic vegetation distribution in IAP-DGVM, including spatial patterns, total areas, and compositions. Moreover, IAP-DGVM also produced more accurate carbon fluxes than CoLM-DGVM when compared with observational estimates. Gross primary productivity and net primary production in IAP-DGVM were in better agreement with observations than those of CoLM-DGVM, and the tropical pattern of fire carbon emissions in IAP-DGVM was much more consistent with the observation than that in CoLM-DGVM. The leaf area index simulated by IAP-DGVM was closer to the observation than that of CoLM-DGVM; however, both simulated values about twice as large as in the observation. This evaluation provides valuable information for the application of CAS-ESM, as well as for other model communities in terms of a comparative benchmark.

Complex Genetic Effects on Early Vegetative Development Shape Resource Allocation Differences Between Arabidopsis lyrata Populations

PubMed Central

Remington, David L.; Leinonen, Päivi H.; Leppälä, Johanna; Savolainen, Outi

2013-01-01

Costs of reproduction due to resource allocation trade-offs have long been recognized as key forces in life history evolution, but little is known about their functional or genetic basis. Arabidopsis lyrata, a perennial relative of the annual model plant A. thaliana with a wide climatic distribution, has populations that are strongly diverged in resource allocation. In this study, we evaluated the genetic and functional basis for variation in resource allocation in a reciprocal transplant experiment, using four A. lyrata populations and F2 progeny from a cross between North Carolina (NC) and Norway parents, which had the most divergent resource allocation patterns. Local alleles at quantitative trait loci (QTL) at a North Carolina field site increased reproductive output while reducing vegetative growth. These QTL had little overlap with flowering date QTL. Structural equation models incorporating QTL genotypes and traits indicated that resource allocation differences result primarily from QTL effects on early vegetative growth patterns, with cascading effects on later vegetative and reproductive development. At a Norway field site, North Carolina alleles at some of the same QTL regions reduced survival and reproductive output components, but these effects were not associated with resource allocation trade-offs in the Norway environment. Our results indicate that resource allocation in perennial plants may involve important adaptive mechanisms largely independent of flowering time. Moreover, the contributions of resource allocation QTL to local adaptation appear to result from their effects on developmental timing and its interaction with environmental constraints, and not from simple models of reproductive costs. PMID:23979581

INSIGHT responsive parenting intervention is associated with healthier patterns of dietary exposures in infants.

PubMed

Hohman, Emily E; Paul, Ian M; Birch, Leann L; Savage, Jennifer S

2017-01-01

To determine whether a responsive parenting (RP) intervention affects infant dietary patterns. Primiparous mother-newborn dyads (n = 291) were randomized to the Intervention Nurses Start Infants Growing on Healthy Trajectories (INSIGHT) RP intervention or control. Curricula were delivered at nurse home visits at ages 3, 16, 28, and 40 weeks. RP group feeding guidance advised responsive feeding, delayed introduction of solids, repeated exposure to novel foods, and age-appropriate portion sizes. Latent class analysis identified patterns of dietary exposure at 9 months. Class membership at 9 months was used to predict BMI percentile at 2 years. Five dietary patterns were identified: "Breastfed, Fruits and Vegetables," "Breastfed, Low Variety," "Formula, Fruits and Vegetables," "Formula, Low Variety," and "Formula, High Energy Density." Over 60% of infants had patterns low in fruits and vegetables or high in energy-dense foods. RP group infants were less likely than control to be in the "Formula, Low Variety" class (OR = 0.40, 95% CI 0.23-0.71) or "Formula, High Energy Density" class (OR = 0.28, 95% CI 0.12-0.61) relative to the "Formula, Fruits and Vegetables" class. Dietary pattern at 9 months was significantly associated with BMI percentile at 2 years. While a majority of infants consumed diets low in fruits and vegetables, the INSIGHT RP intervention was associated with healthier dietary patterns. © 2016 The Obesity Society.

How Tight is the Linkage Between Trees and Trout?

Treesearch

Margaret A. Wilzbach

1989-01-01

This paper explores the tightness of the linkage between stream-dwelling salmonids and ripar ian vegetation. Comparison of original distributions of salmonid species with that of vegetation types shows that distribution within a given salmonid species is not limited to a specific vegetation type, and that different salmonid species cooccur within a given vegetation...

Shelter Index and a simple wind speed parameter to characterize vegetation control of sand transport threshold and Flu

NASA Astrophysics Data System (ADS)

Gillies, J. A.; Nield, J. M.; Nickling, W. G.; Furtak-Cole, E.

2014-12-01

Wind erosion and dust emissions occur in many dryland environments from a range of surfaces with different types and amounts of vegetation. Understanding how vegetation modulates these processes remains a research challenge. Here we present results from a study that examines the relationship between an index of shelter (SI=distance from a point to the nearest upwind vegetation/vegetation height) and particle threshold expressed as the ratio of wind speed measured at 0.45 times the mean plant height divided by the wind speed at 17 m when saltation commences, and saltation flux. The results are used to evaluate SI as a parameter to characterize the influence of vegetation on local winds and sediment transport conditions. Wind speed, wind direction, saltation activity and point saltation flux were measured at 35 locations in defined test areas (~13,000 m2) in two vegetation communities: mature streets of mesquite covered nebkhas and incipient nebkhas dominated by low mesquite plants. Measurement positions represent the most open areas, and hence those places most susceptible to wind erosion among the vegetation elements. Shelter index was calculated for each measurement position for each 10° wind direction bin using digital elevation models for each site acquired using terrestrial laser scanning. SI can show the susceptibility to wind erosion at different time scales, i.e., event, seasonal, or annual, but in a supply-limited system it can fail to define actual flux amounts due to a lack of knowledge of the distribution of sediment across the surface of interest with respect to the patterns of SI.

Analyzing vegetation dynamics of land systems with satellite data

USGS Publications Warehouse

Eidenshink, Jeffery C.; Haas, Robert H.

1992-01-01

Large area assessment of vegetation conditions is a major requirement for understanding the impact of weather on food, fiber, and forage production. The distribution of vegetation is largely associated with climate, terrain characteristics, and human activity. The interpretation of vegetation dynamics from satellite data can be improved by stratifying the land surface into ecoregions. The Soil Conservation Service, U.S. Department of Agriculture, has developed a system for mapping major land resource areas (MLRA) that groups land areas in the United States on the basis of climate, physiography, land use, and land cover characteristics.In 1989, the U.S. Geological Survey used National Oceanic and Atmospheric Administration weather satellite data to conduct a biweekly assessment of vegetation conditions in 17 western states. Advanced Very High Resolution Radiometer data were acquired daily, and were geographically registered, and the normalized difference vegetation index (NDVI) was computed for the Western United States during the 1989 growing season. Fifteen biweekly NDVI data sets were used to evaluate MLRA's as an appropriate stratification for monitoring and interpreting vegetation conditions in the study area.The results demonstrate the feasibility of using MLRA's to stratify areas for monitoring phenological development and vegetation condition assessment within the growing season. Assessments of the NDVI at biweekly intervals are adequate for monitoring seasonal growth patterns on MLRA's where rangelands, forests, or cultivated agriculture are the primary resource type. Descriptive statistics are indicators of the uniformity or diversity of land use and land cover within an MLRA. Growing season profiles of the NDVI are characterized by the seasonal effects of climate on various land use and land cover classes.

Fire and ecosystem change in the Arctic across the Paleocene-Eocene Thermal Maximum

NASA Astrophysics Data System (ADS)

Denis, E. H.; Pedentchouk, N.; Schouten, S.; Pagani, M.; Freeman, K. H.

2016-12-01

Fire, an important component of ecosystems at a range of spatial and temporal scales, affects vegetation distribution, the carbon cycle, and climate. In turn, climate influences fuel composition (e.g., amount and type of vegetation), fuel availability (e.g., vegetation that can burn based on precipitation and temperature), and ignition sources (e.g., lightning). Climate studies predict increased wildfire activity in future decades, but mechanisms that control the relationship between climate and fire are complex. Reconstructing environmental conditions during past warming events (e.g., the Paleocene-Eocene Thermal Maximum (PETM)) will help elucidate climate-vegetation-fire relationships that are expressed over long durations (1,000 - 10,000 yrs). The abrupt global warming during the PETM dramatically altered vegetation and hydrologic patterns, and, possibly, fire occurrence. To investigate coincident changes in climate, vegetation, and fire occurrence, we studied biomarkers, including polycyclic aromatic hydrocarbons (PAHs), terpenoids, and alkanes from the PETM interval at IODP site 302 (the Lomonosov Ridge) in the Arctic Ocean. Both pollen and biomarker records indicate angiosperms abundance increased during the PETM relative to gymnosperms, reflecting a significant ecological shift to angiosperm-dominated vegetation. PAH abundances increased relative to plant biomarkers throughout the PETM, which suggests PAH production increased relative to plant productivity. Increased PAH production associated with the angiosperm vegetation shift indicates a greater prevalence of more fire-prone species. A time lag between increased moisture transport (based on published δD of n-alkanes data) to the Arctic and increased angiosperms and PAH production suggests wetter conditions, followed by increased air temperatures, favored angiosperms and combined to enhance fire occurrence.

Vegetation classification, mapping, and monitoring at Voyageurs National Park, Minnesota: An application of the U.S. National Vegetation Classification

USGS Publications Warehouse

Faber-Langendoen, D.; Aaseng, N.; Hop, K.; Lew-Smith, M.; Drake, J.

2007-01-01

Question: How can the U.S. National Vegetation Classification (USNVC) serve as an effective tool for classifying and mapping vegetation, and inform assessments and monitoring? Location: Voyageurs National Park, northern Minnesota, U.S.A and environs. The park contains 54 243 ha of terrestrial habitat in the sub-boreal region of North America. Methods: We classified and mapped the natural vegetation using the USNVC, with 'alliance' and 'association' as base units. We compiled 259 classification plots and 1251 accuracy assessment test plots. Both plot and type ordinations were used to analyse vegetation and environmental patterns. Color infrared aerial photography (1:15840 scale) was used for mapping. Polygons were manually drawn, then transferred into digital form. Classification and mapping products are stored in publicly available databases. Past fire and logging events were used to assess distribution of forest types. Results and Discussion: Ordination and cluster analyses confirmed 49 associations and 42 alliances, with three associations ranked as globally vulnerable to extirpation. Ordination provided a useful summary of vegetation and ecological gradients. Overall map accuracy was 82.4%. Pinus banksiana - Picea mariana forests were less frequent in areas unburned since the 1930s. Conclusion: The USNVC provides a consistent ecological tool for summarizing and mapping vegetation. The products provide a baseline for assessing forests and wetlands, including fire management. The standardized classification and map units provide local to continental perspectives on park resources through linkages to state, provincial, and national classifications in the U.S. and Canada, and to NatureServe's Ecological Systems classification. ?? IAVS; Opulus Press.

A data-driven approach to identify controls on global fire activity from satellite and climate observations (SOFIA V1)

NASA Astrophysics Data System (ADS)

Forkel, Matthias; Dorigo, Wouter; Lasslop, Gitta; Teubner, Irene; Chuvieco, Emilio; Thonicke, Kirsten

2017-12-01

Vegetation fires affect human infrastructures, ecosystems, global vegetation distribution, and atmospheric composition. However, the climatic, environmental, and socioeconomic factors that control global fire activity in vegetation are only poorly understood, and in various complexities and formulations are represented in global process-oriented vegetation-fire models. Data-driven model approaches such as machine learning algorithms have successfully been used to identify and better understand controlling factors for fire activity. However, such machine learning models cannot be easily adapted or even implemented within process-oriented global vegetation-fire models. To overcome this gap between machine learning-based approaches and process-oriented global fire models, we introduce a new flexible data-driven fire modelling approach here (Satellite Observations to predict FIre Activity, SOFIA approach version 1). SOFIA models can use several predictor variables and functional relationships to estimate burned area that can be easily adapted with more complex process-oriented vegetation-fire models. We created an ensemble of SOFIA models to test the importance of several predictor variables. SOFIA models result in the highest performance in predicting burned area if they account for a direct restriction of fire activity under wet conditions and if they include a land cover-dependent restriction or allowance of fire activity by vegetation density and biomass. The use of vegetation optical depth data from microwave satellite observations, a proxy for vegetation biomass and water content, reaches higher model performance than commonly used vegetation variables from optical sensors. We further analyse spatial patterns of the sensitivity between anthropogenic, climate, and vegetation predictor variables and burned area. We finally discuss how multiple observational datasets on climate, hydrological, vegetation, and socioeconomic variables together with data-driven modelling and model-data integration approaches can guide the future development of global process-oriented vegetation-fire models.

Concentrations and health risk assessment of rare earth elements in vegetables from mining area in Shandong, China.

PubMed

Zhuang, Maoqiang; Zhao, Jinshan; Li, Suyun; Liu, Danru; Wang, Kebo; Xiao, Peirui; Yu, Lianlong; Jiang, Ying; Song, Jian; Zhou, Jingyang; Wang, Liansen; Chu, Zunhua

2017-02-01

To investigate the concentrations of rare earth elements in vegetables and assess human health risk through vegetable consumption, a total of 301 vegetable samples were collected from mining area and control area in Shandong, China. The contents of 14 rare earth elements were determined by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). The total rare earth elements in vegetables from mining and control areas were 94.08 μg kg -1 and 38.67 μg kg -1 , respectively, and the difference was statistically significant (p < 0.05). The leaf vegetable had the highest rare earth elements concentration (984.24 μg kg -1 and 81.24 μg kg -1 for mining and control areas, respectively) and gourd vegetable had the lowest rare earth elements concentration (37.34 μg kg -1 and 24.63 μg kg -1 for mining and control areas, respectively). For both areas, the rare earth elements concentration in vegetables declined in the order of leaf vegetable > taproot vegetable > alliaceous vegetable > gourd vegetable. The rare earth elements distribution patterns for both areas were characterized by enrichment of light rare earth elements. The health risk assessment demonstrated that the estimated daily intakes (0.69 μg kg -1 d -1 and 0.28 μg kg -1 d -1 for mining and control areas, respectively) of rare earth elements through vegetable consumption were significantly lower than the acceptable daily intake (70 μg kg -1 d -1 ). The damage to adults can be neglected, but more attention should be paid to the effects of continuous exposure to low levels of rare earth elements on children. Copyright © 2016 Elsevier Ltd. All rights reserved.

The benefits of authoritative feeding style: caregiver feeding styles and children's food consumption patterns.

PubMed

Patrick, Heather; Nicklas, Theresa A; Hughes, Sheryl O; Morales, Miriam

2005-04-01

This research tested the associations between caregiver feeding styles and children's food consumption patterns among African-American (AA) and Hispanic (H) caregivers and their preschool children. Participants were 231 caregivers (101 AA; 130 H) with children enrolled in Head Start. Caregivers completed questionnaires on authoritarian and authoritative feeding styles (Caregiver's Feeding Styles Questionnaire; CFSQ) and various aspects of children's food consumption patterns (availability of, feeding attempts for, and child's consumption of dairy, fruit, and vegetables). Simultaneous multiple regression analyses tested the unique contribution of feeding styles in predicting food consumption patterns. Authoritative feeding was positively associated whereas authoritarian feeding was negatively associated with the availability of fruit and vegetables. Authoritative feeding was also positively associated with attempts to get the child to eat dairy, fruit, and vegetables, and reported child consumption of dairy and vegetables. Authoritarian feeding was negatively associated with child's vegetable consumption. All results remained significant after controlling for child's gender and body mass index (BMI), and caregiver's ethnicity, BMI, and level of education. Overall, results provide evidence for the benefits of authoritative feeding and suggest that interventions to increase children's consumption of dairy, fruit, and vegetables should be targeted toward increasing caregivers' authoritative feeding behaviors.

Depletion and Redistribution of Soil Nutrients in Response to Wind Erosion in Desert Grasslands of the Southwestern United States

NASA Astrophysics Data System (ADS)

Li, J.; Okin, G.; Hartman, L.; Epstein, H.

2005-12-01

Wind is a key abiotic factor that determines the spatial distribution of soil nutrients in arid grasslands with large unvegetated gaps, such as those found in the southwestern US. On the landscape scale, basic relationships such as wind erosion rate vs. vegetative cover, and soil nutrient removal rate vs. vegetative cover have not yet been extensively studied. In a series of experiments conducted in the Jornada Experimental Range near Las Cruces, New Mexico, we have examined these relationships to determine the impact of wind erosion and dust emission on pools of soil nutrients. In the experiments, varying levels of cover were achieved by vegetation removal on 25 m x 50 m plots. Intense surface soil sampling was conducted to monitor spatial distribution of soil nutrients. Large numbers of aeolian sediment samplers were installed to obtain estimates of vertical and horizontal dust flux. Available data from one wind erosion season show that: 1) total organic C (TOC) and total N (TN) content in the windblown sediment collected at the height of 1 m were 2.2 to 7.2 times larger than those of nutrients in the surface soil (enrichment ratio); 2) enrichment ratio generally increases with the increase of vegetative cover, indicating biotic processes continually add nutrients to surface soil in high-cover treatments, while nutrients are depleted in low-cover treatments; 3) average horizontal mass flux is 12 times larger in the bare plot than in the control plot, indicating the extreme importance of vegetative cover in protecting soil nutrient loss caused by wind erosion; 4) detectable soil nutrient depletion happened within one windy season in plots with vegetation removal, especially for TOC and TN, reflecting the importance of biotic processes in maintaining nutrient pools in the surface soil; and, 5) after only a single windy season, wind erosion can significantly alter the spatial pattern of soil nutrients.

Direct and indirect effects of climate change on projected future fire regimes in the western United States.

PubMed

Liu, Zhihua; Wimberly, Michael C

2016-01-15

We asked two research questions: (1) What are the relative effects of climate change and climate-driven vegetation shifts on different components of future fire regimes? (2) How does incorporating climate-driven vegetation change into future fire regime projections alter the results compared to projections based only on direct climate effects? We used the western United States (US) as study area to answer these questions. Future (2071-2100) fire regimes were projected using statistical models to predict spatial patterns of occurrence, size and spread for large fires (>400 ha) and a simulation experiment was conducted to compare the direct climatic effects and the indirect effects of climate-driven vegetation change on fire regimes. Results showed that vegetation change amplified climate-driven increases in fire frequency and size and had a larger overall effect on future total burned area in the western US than direct climate effects. Vegetation shifts, which were highly sensitive to precipitation pattern changes, were also a strong determinant of the future spatial pattern of burn rates and had different effects on fire in currently forested and grass/shrub areas. Our results showed that climate-driven vegetation change can exert strong localized effects on fire occurrence and size, which in turn drive regional changes in fire regimes. The effects of vegetation change for projections of the geographic patterns of future fire regimes may be at least as important as the direct effects of climate change, emphasizing that accounting for changing vegetation patterns in models of future climate-fire relationships is necessary to provide accurate projections at continental to global scales. Copyright © 2015 Elsevier B.V. All rights reserved.

Dietary Patterns and Body Mass Index in Children with Autism and Typically Developing Children

ERIC Educational Resources Information Center

Evans, E. Whitney; Must, Aviva; Anderson, Sarah E.; Curtin, Carol; Scampini, Renee; Maslin, Melissa; Bandini, Linda

2012-01-01

To determine whether dietary patterns (juice and sweetened non-dairy beverages, fruits, vegetables, fruits and vegetables, snack foods, and kid's meals) and associations between dietary patterns and body mass index (BMI) differed between 53 children with autism spectrum disorders (ASD) and 58 typically developing children, ages 3-11, multivariate…

On the role of patterns in understanding the functioning of soil-vegetation-atmosphere systems

USDA-ARS?s Scientific Manuscript database

In this paper, we review the role of patterns to improve our understanding of water, mass and energy exchange processes in soil-vegetation-atmosphere systems. We explore the main mechanisms that lead to the formation of patterns in these systems and discuss different approaches to characterizing and...

Ecoregions as a level of ecological analysis

USGS Publications Warehouse

Wright, R.G.; Murray, M.P.; Merrill, T.

1998-01-01

There have been many attempts to classify geographic areas into zones of similar characteristics. Recent focus has been on ecoregions. We examined how well the boundaries of the most commonly used ecoregion classifications for the US matched the boundaries of existing vegetation cover mapped at three levels of classification, fine, mid- and coarse scale. We analyzed ecoregions in Idaho, Oregon and Washington. The results were similar among the two ecoregion classifications. For both ecoregion delineations and all three vegetation classifications, the patterns of existing vegetation did not correspond well with the patterns of ecoregions. Most vegetation types had a small proportion of their total area in a given ecoregion. There was also no dominance by one or more vegetation types in any ecoregion and contrary to our hypothesis, the level of congruence of vegetation patterns with ecoregion boundaries decreased as the level of classification became more general. The implications of these findings on the use of ecoregions as a planning tool and in the development of land conservation efforts are discussed.

Some ecological attributes and plutonium contents of perennial vegetation in Area 13

DOE Office of Scientific and Technical Information (OSTI.GOV)

Romney, E.M.; Wallace, A.; Gilbert, R.O.

1973-11-01

Progress is reported on work conducted at the Nevada Test Site under the auspices of the Nevada Applied Ecology Group, Office of Effects Evaluation, USAEC Nevada Operations Office, Las Vegas. Nevada. Included are data on some ecological attributes of the vegetation within thc fenced portion of the Project 57 fallout pattern in Area 13. Also included are some preliminary data on the / sup 239/-240/Pu and /sup 241/Am in samples of vegetation collected in conjunction with the soil sampling program. Prominent shrub and grass species in the fallout pattern of Area 13 include Artemisia spinescens, Atriplex canescens, Atriplex confertifolia, Eurotiamore » lanata, Grayia spinosa, Kochia americana, Lycium andersonii, and Oryzopsis hymenoides. Individual or co-dominant species distinguished local association pattarns of varied size within the fenced study area. Vegetation cover estimates in sample study plots ranged from 12.8 to 25.3 percent. Shrub densities ranged from 11.2 x 10/sup 3/ to 17.9 x 10/sup 3/ plants per hectare, and the standing shrub biomass ranged from 1592 to 4255 kilograms per hectare (0.7 to 1.9 tons per acre). Preliminary results showed rather uniform distributions of /sup 239-240/Pu and /sup 241/Am among indiividual samples of the same plant species collected within an intensive study plot. However, there was considerable variation in the contamination levels between different species, presumably from superficial entrapment of resuspended particulate material. Concentrations in Eurotia lanata were three to five times higher than in other species sampled from the same study site. The /sup 239-240/ Pu and /sup 241/Am generally tended to decrease in samples of vegetation collected at increasing distances from ground zero, but there were poor correlations between vegetation and soil /sup 239-240/Pu concertrations in isopleth strat within the fenced grazing area. Results showed inconsistencies in the Pu/Am ratios for vegettion and soil. Lower ratios found in vegetation samples indicate that preferential uptake and concentration of /sup 241/Am through plant roots might have occurred in the Project 57 fallout area. (auth)« less

Ecogeomorphology of semiarid rangelands: understanding and quantifying rates and feedbacks to prevent landscape degradation.

NASA Astrophysics Data System (ADS)

Saco, Patricia; Azadi, Samira; Moreno-de las Heras, Mariano; Keesstra, Saskia

2017-04-01

In semiarid systems, hydrologic, geomorphic and ecological processes are tightly coupled through strong feedback mechanisms occurring across fine to coarse scales. These feedbacks have implications for equilibrium and resilience of the landscape and are particularly relevant for understanding the potential degradation effects of climate and anthropogenic pressures. The vegetation of these regions is sparse and often associated to the development and maintenance of spatially variable infiltration rates, with lower infiltration in the bare areas. These variable infiltration rates have been observed in many field studies and are responsible for the emergence of a runoff-runon system, and for the associated redistribution of water and sediments. We will present a modelling framework developed to understand the role of surface water connectivity in degradation processes in semiarid landscapes with patchy vegetation. Surface water connectivity in these systems is highly dynamic and emerges from non-linear feedbacks between vegetation patterns and the coevolving landforms. The model captures these feedbacks through the coupled nature of the processes included in the landform-vegetation modules. As increased surface runoff connectivity has been linked to degradation, we focus on evolving hydrologic connectivity patterns resulting from feedback effects and co-evolving structures. First, we will discuss some general results on the coevolution of semiarid rangelands, and the effects of varying abiotic and biotic conditions. Next we will present results in which we investigate changes in functional hydrologic connectivity, and the existence of tipping points as observed in several sites in Australia. These results are based on data from our recent studies along a precipitation gradient in the Mulga bioregion of Australia. The analysis from satellite images reveals a major role of surface connectivity on the spatial organization of patchy vegetation, suggesting that transitions on the distribution of vegetation leading to degradation are related to sharp variations on the landscape surface connectivity. Finally we will discuss results analysing the potential effect of soils depths on the coevolution of system structures and connectivity. The relevance and implications of these results for the successful reclamation of water-limited environments in which vegetation stability largely depends on the redistribution of the scarce water resources will be discussed.

Tropical climate and vegetation changes during Heinrich Event 1: comparing climate model output to pollen-based vegetation reconstructions with emphasis on the region around the tropical Atlantic Ocean

NASA Astrophysics Data System (ADS)

Handiani, D.; Paul, A.; Dupont, L.

2011-06-01

Abrupt climate changes associated with Heinrich Event 1 (HE1) about 18 to 15 thousand years before present (ka BP) strongly affected climate and vegetation patterns not only in the Northern Hemisphere, but also in tropical regions in the South Atlantic Ocean. We used the University of Victoria (UVic) Earth System-Climate Model (ESCM) with dynamical vegetation and land surface components to simulate four scenarios of climate-vegetation interaction: the pre-industrial era (PI), the Last Glacial Maximum (LGM), and a Heinrich-like event with two different climate backgrounds (interglacial and glacial). The HE1-like simulation with a glacial climate background produced sea surface temperature patterns and enhanced interhemispheric thermal gradients in accordance with the "bipolar seesaw" hypothesis. It allowed us to investigate the vegetation changes that result from a transition to a drier climate as predicted for northern tropical Africa due to a southward shift of the Intertropical Convergence Zone (ITCZ). We found that a cooling of the Northern Hemisphere caused a southward shift of those plant-functional types (PFTs) in Northern Tropical Africa that are indicative of an increased desertification, and a retreat of broadleaf forests in Western Africa and Northern South America. We used the PFTs generated by the model to calculate mega-biomes to allow for a direct comparison between paleodata and palynological vegetation reconstructions. Our calculated mega-biomes for the pre-industrial period and the LGM corresponded well to the modern and LGM sites of the BIOME6000 (v.4.2) reconstruction, except that our present-day simulation predicted the dominance of grassland in Southern Europe and our LGM simulation simulated more forest cover in tropical and sub-tropical South America. The mega-biomes from the HE1 simulation with glacial background climate were in agreement with paleovegetation data from land and ocean proxies in West, Central, and Northern Tropical Africa as well as Northeast South America. However, our model did not agree well with predicted biome distributions in Eastern South America.

Solar radiation and landscape evolution: co-evolution of topography, vegetation, and erosion rates in a semi-arid ecosystem

NASA Astrophysics Data System (ADS)

Istanbulluoglu, Erkan; Yetemen, Omer

2016-04-01

In this study CHILD landscape evolution model (LEM) is used to study the role of solar radiation on the co-evolution of landscape morphology, vegetation patterns, and erosion rates in a central New Mexico catchment. In the study site north facing slopes (NFS) are characterized by steep diffusion-dominated planar hillslopes covered by co-exiting juniper pine and grass vegetation. South facing slopes (SFS) are characterized by shallow slopes and covered by sparse shrub vegetation. Measured short-term and Holocene-averaged erosion rates show higher soil loss on SFS than NFS. In this study CHILD LEM is first confirmed with ecohydrologic field data and used to systematically examine the co-evolution of topography, vegetation pattern, and erosion rates. Aspect- and network-control are identified as the two main topographic drivers of soil moisture and vegetation organization on the landscape. Landscape-scale and long-term implications of solar radiation driven ecohdrologic patterns emerged in modeled landscape: NFS supported denser vegetation cover and became steeper and planar, while on SFS vegetation grew sparser and slopes declined with more fluvial activity. At the landscape scale, these differential erosion processes led to asymmetric development of catchment forms, consistent with regional observations. While the general patterns of vegetation and topography were reproduced by the model using a stationary representation of the current climate, the observed differential Holocene erosion rates were captured by the model only when cyclic climate is used. This suggests sensitivity of Holocene erosion rates to long-term climate fluctuations.

Comparative phylogeography of eight herbs and lianas (Marantaceae) in central African rainforests.

PubMed

Ley, Alexandra C; Dauby, Gilles; Köhler, Julia; Wypior, Catherina; Röser, Martin; Hardy, Olivier J

2014-01-01

Vegetation history in tropical Africa is still to date hardly known and the drivers of population differentiation and speciation processes are little documented. It has often been postulated that population fragmentations following climate changes have played a key role in shaping the geographic distribution patterns of genetic diversity and in driving speciation. Here we analyzed phylogeographic patterns (chloroplast-DNA sequences) within and between eight (sister) species of widespread rainforest herbs and lianas from four genera of Marantaceae (Halopegia, Haumania, Marantochloa, Megaphrynium), searching for concordant patterns across species and concordance with the Pleistocene refuge hypothesis. Using 1146 plastid DNA sequences sampled across African tropical lowland rainforest, particularly in the Lower Guinean (LG) phytogeographic region, we analyzed intra- and interspecific patterns of genetic diversity, endemism and distinctiveness. Intraspecific patterns of haplotype diversity were concordant among most species as well as with the species-level diversity pattern of Marantaceae. Highest values were found in the hilly areas of Cameroon and Gabon. However, the spatial distribution of endemic haplotypes, an indicator for refuge areas in general, was not congruent across species. Each proposed refuge exhibited high values of endemism for one or a few species indicating their potential role as area of retraction for the respective species only. Thus, evolutionary histories seem to be diverse across species. In fact, areas of high diversity might have been both refuge and/or crossing zone of recolonization routes i.e., secondary contact zone. We hypothesize that retraction of species into one or the other refuge happened by chance depending on the species' distribution range at the time of climate deterioration. The idiosyncratic patterns found in Marantaceae species are similar to those found among tropical tree species, especially in southern LG.

Comparative phylogeography of eight herbs and lianas (Marantaceae) in central African rainforests

PubMed Central

Ley, Alexandra C.; Dauby, Gilles; Köhler, Julia; Wypior, Catherina; Röser, Martin; Hardy, Olivier J.

2014-01-01

Vegetation history in tropical Africa is still to date hardly known and the drivers of population differentiation and speciation processes are little documented. It has often been postulated that population fragmentations following climate changes have played a key role in shaping the geographic distribution patterns of genetic diversity and in driving speciation. Here we analyzed phylogeographic patterns (chloroplast-DNA sequences) within and between eight (sister) species of widespread rainforest herbs and lianas from four genera of Marantaceae (Halopegia, Haumania, Marantochloa, Megaphrynium), searching for concordant patterns across species and concordance with the Pleistocene refuge hypothesis. Using 1146 plastid DNA sequences sampled across African tropical lowland rainforest, particularly in the Lower Guinean (LG) phytogeographic region, we analyzed intra- and interspecific patterns of genetic diversity, endemism and distinctiveness. Intraspecific patterns of haplotype diversity were concordant among most species as well as with the species-level diversity pattern of Marantaceae. Highest values were found in the hilly areas of Cameroon and Gabon. However, the spatial distribution of endemic haplotypes, an indicator for refuge areas in general, was not congruent across species. Each proposed refuge exhibited high values of endemism for one or a few species indicating their potential role as area of retraction for the respective species only. Thus, evolutionary histories seem to be diverse across species. In fact, areas of high diversity might have been both refuge and/or crossing zone of recolonization routes i.e., secondary contact zone. We hypothesize that retraction of species into one or the other refuge happened by chance depending on the species' distribution range at the time of climate deterioration. The idiosyncratic patterns found in Marantaceae species are similar to those found among tropical tree species, especially in southern LG. PMID:25477901

Influence of different topographic correction strategies on mountain vegetation classification accuracy in the Lancang Watershed, China

NASA Astrophysics Data System (ADS)

Zhang, Zhiming; de Wulf, Robert R.; van Coillie, Frieke M. B.; Verbeke, Lieven P. C.; de Clercq, Eva M.; Ou, Xiaokun

2011-01-01

Mapping of vegetation using remote sensing in mountainous areas is considerably hampered by topographic effects on the spectral response pattern. A variety of topographic normalization techniques have been proposed to correct these illumination effects due to topography. The purpose of this study was to compare six different topographic normalization methods (Cosine correction, Minnaert correction, C-correction, Sun-canopy-sensor correction, two-stage topographic normalization, and slope matching technique) for their effectiveness in enhancing vegetation classification in mountainous environments. Since most of the vegetation classes in the rugged terrain of the Lancang Watershed (China) did not feature a normal distribution, artificial neural networks (ANNs) were employed as a classifier. Comparing the ANN classifications, none of the topographic correction methods could significantly improve ETM+ image classification overall accuracy. Nevertheless, at the class level, the accuracy of pine forest could be increased by using topographically corrected images. On the contrary, oak forest and mixed forest accuracies were significantly decreased by using corrected images. The results also showed that none of the topographic normalization strategies was satisfactorily able to correct for the topographic effects in severely shadowed areas.

The combined effects of topography and vegetation on catchment connectivity

NASA Astrophysics Data System (ADS)

Nippgen, F.; McGlynn, B. L.; Emanuel, R. E.

2012-12-01

The deconvolution of whole catchment runoff response into its temporally dynamic source areas is a grand challenge in hydrology. The extent to which the intersection of static and dynamic catchment characteristics (e.g. topography and vegetation) influences water redistribution within a catchment and the hydrologic connectivity of hillslopes to the riparian and stream system is largely unknown. Over time, patterns of catchment storage shift and, because of threshold connectivity behavior, catchment areas become disconnected from the stream network. We developed a simple but spatially distributed modeling framework that explicitly incorporates static (topography) and dynamic (vegetation) catchment structure to document the evolution of catchment connectivity over the course of a water year. We employed directly measured eddy-covariance evapotranspiration data co-located within a highly instrumented (>150 recording groundwater wells) and gauged catchment to parse the effect of current and zero vegetation scenarios on the temporal evolution of hydrologic connectivity. In the absence of vegetation, and thus in the absence of evapotranspiration, modeled absolute connectivity was 4.5% greater during peak flow and 3.9% greater during late summer baseflow when compared to the actual vegetation scenario. The most significant differences in connected catchment area between current and zero vegetation (14.9%) occurred during the recession period in early July, when water and energy availability were at an optimum. However, the greatest relative difference in connected area occurs during the late summer baseflow period when the absence of evapotranspiration results in a connected area approximately 500% greater than when vegetation is present, while the relative increase during peak flow is just 6%. Changes in connected areas ultimately lead to propose a biologically modified geomorphic width function. This biogeomorphic width function is the result of lateral water redistribution driven by topography and water uptake by vegetation.

Edaphic fauna in a vegetation gradient in the Sete Cidades National Park.

PubMed

Nunes, L A P L; Araújo, A S F; Pessoa, M M C; Sousa, R S; Silva, J D C; Matos-Filho, C H A

2018-04-09

The vegetation physionomy and cover can show patterns of diversity and composition of the edaphic community, depending on the quantity and quality of litter in a specific habitat. The objective of this study was to evaluate the effect of the vegetation gradient formed by Graminoid Field (GRF), Cerrado Sensu Stricto (CSS), Cerradão (CRD) and Semideciduous Seasonal Forest (SSF) on density, diversity and composition of the edaphic fauna community in two seasons of the year, in the Sete Cidades National Park (Piauí state). For fauna sampling, a total of eight pitfall traps, distanced 10 m, were placed in each area in the central part of each system, where they remained for seven days. In the wet period, there was a tendency to increase the number of individuals as a function of the complexity of the vegetation formation, with the inverse occurring in the dry period. It was verified an environmental variation of the climatic factors temperature and humidity according to the vegetal formation, contributing to a heterogeneous distribution of the fauna. The GRF formation presented a significantly lower value of average richness only in the dry period. Regarding the variables of diversity and uniformity, they did not show drastic variations in relation to the vegetation gradient studied. The dominant groups in the vegetation gradient were Formicidae, Coleoptera, Aranae, Acari and Collembola, with reduction of the number of Coleoptera in the dry season. Principal component analysis (PCA) revealed greater differences in the composition of the communities between the vegetation formations for the rainy season. At this time, the formations SSF and CRD were associated to a greater diversity of invertebrates than CSS and GRF, demonstrating the influence of the vegetation complexity on the soil fauna community.

Ground-Vegetation Clutter Affects Phyllostomid Bat Assemblage Structure in Lowland Amazonian Forest.

PubMed

Marciente, Rodrigo; Bobrowiec, Paulo Estefano D; Magnusson, William E

2015-01-01

Vegetation clutter is a limiting factor for bats that forage near ground level, and may determine the distribution of species and guilds. However, many studies that evaluated the effects of vegetation clutter on bats have used qualitative descriptions rather than direct measurements of vegetation density. Moreover, few studies have evaluated the effect of vegetation clutter on a regional scale. Here, we evaluate the influence of the physical obstruction of vegetation on phyllostomid-bat assemblages along a 520 km transect in continuous Amazonian forest. We sampled bats using mist nets in eight localities during 80 nights (3840 net-hours) and estimated the ground-vegetation density with digital photographs. The total number of species, number of animalivorous species, total number of frugivorous species, number of understory frugivorous species, and abundance of canopy frugivorous bats were negatively associated with vegetation clutter. The bat assemblages showed a nested structure in relation to degree of clutter, with animalivorous and understory frugivorous bats distributed throughout the vegetation-clutter gradient, while canopy frugivores were restricted to sites with more open vegetation. The species distribution along the gradient of vegetation clutter was not closely associated with wing morphology, but aspect ratio and wing load differed between frugivores and animalivores. Vegetation structure plays an important role in structuring assemblages of the bats at the regional scale by increasing beta diversity between sites. Differences in foraging strategy and diet of the guilds seem to have contributed more to the spatial distribution of bats than the wing characteristics of the species alone.

Field and remote sensing for findings on the functions and evolutions of deltas

NASA Astrophysics Data System (ADS)

Taramelli, A.; Valentini, E.

2013-12-01

In a rapidly changing environment we realise that traditional knowledge of physical processes (both biotic and a-biotic) is insufficient to adequately deal with societal threats and opportunities particularly in low laying deltas, such changes to environments as a result of urbanization or changes to ecosystems as a result of climate change. Pattern formation and strong bio-morphological interactions are a striking features in deltas: vegetation distribution has been observed to be related with tidal channel network, with wind/wave forces as well as with the urbanization and natural built, but the relationship between the relevant biological, physical and anthropogenic processes are fairly unexplored. Through the combination of spaceborne optical and SAR imagery, we derived both ecological and morphological parameters, to be integrated for a multi-temporal analysis of the dominant processes and trends in a specific delta. Based on inter annual and intra annual time series of fractional abundance from multispectral imagery, the vegetation phenology in urbanized, non urbanized and buffer zones of the Po delta and adjoin wetlands were calculated and the relationship between them and the major physical drivers was studied. The results highlight that over time, the dynamics of different subsystems represents a balance between inputs (forcing agents like climate) and natural responses (related responses like the vegetation evolution) relevant to urbanization. Basically the urbanization is strongly linked with the phenology and spatial patterns of vegetation cover and not with the channel distribution. Agricultural and farmers uses are in fact the urban edges and they didn't changed obviously if seasonal trends are subtracted from the inter-annual ones. Changes in buffer zones if they were closer to urban or agricultural areas were observed different from the adjoining coastal areas. Finally the uncertainties calculation of the Delta system (i.e. subsidence rates or erosion rates) using new monitoring techniques such as satellite remote sensing shows to be a specific added value that could be used for simulations over varying time scales and it should be considered as a potential ';add in' for an integrated management approach that could be exported in major delta (i.e. Mekong).

Rooting strategies in a subtropical savanna: a landscape-scale three-dimensional assessment.

PubMed

Zhou, Yong; Boutton, Thomas W; Wu, X Ben; Wright, Cynthia L; Dion, Anais L

2018-04-01

In resource-limited savannas, the distribution and abundance of fine roots play an important role in acquiring essential resources and structuring vegetation patterns and dynamics. However, little is known regarding the three-dimensional distribution of fine roots in savanna ecosystems at the landscape scale. We quantified spatial patterns of fine root density to a depth of 1.2 m in a subtropical savanna landscape using spatially specific sampling. Kriged maps revealed that fine root density was highest at the centers of woody patches, decreased towards the canopy edges, and reached lowest values within the grassland matrix throughout the entire soil profile. Lacunarity analyses indicated that spatial heterogeneities of fine root density decreased continuously to a depth of 50 cm and then increased in deeper portions of the soil profile across this landscape. This vertical pattern might be related to inherent differences in root distribution between trees/shrubs and herbaceous species, and the presence/absence of an argillic horizon across this landscape. The greater density of fine roots beneath woody patches in both upper and lower portions of the soil profile suggests an ability to acquire disproportionately more resources than herbaceous species, which may facilitate the development and persistence of woody patches across this landscape.

Biomarker patterns in present-day vegetation: consistency and variation - A study on plaggen soils

NASA Astrophysics Data System (ADS)

Kirkels, Frédérique; Jansen, Boris; Kalbitz, Karsten

2013-04-01

Biomarker patterns in present-day vegetation are commonly used as proxies to reconstruct paleo-vegetation composition, land use history and to elucidate carbon cycling. Plaggen soils are formed by diverse vegetational inputs during century-long plaggen (i.e. sod) application associated with plaggen-agriculture on poor soils in north-western Europe. This resulted in remarkably stable organic matter. Plant source identification by biomarkers could provide insight in yet unknown stabilization mechanisms and the fate of organic matter upon ongoing land use change. The current rationale behind biomarker-based source identification is that patterns observed in present-day vegetation are generally representative with little random variation. However, our knowledge on variability and consistency of biomarker patterns is yet scarce. Therefore, to assess the applicability of biomarkers for source identification in plaggen soils, we analyzed published n-alkane and n-alcohol patterns of species and their various parts which contribute(d) input to plaggen soils. We considered shrubs, trees and grass species and evaluated rescaled patterns (i.e. relative abundances in chain-length range C17-36), odd-over-even predominance (OEP) and predominant n-alkanes. In addition, we explicitly looked into potential sources of systematic variation, e.g. spatial variation (climate, site conditions), temporal variation (seasonality, ontogeny) and laboratory methodology (extraction technique: washing/shaking, Soxhlet/ASE, saponification). We found meaningful clustering of n-alkanes C27, C29, C31 and C33, allowing for clear distinction of input by shrubs, trees and grasses to plaggen soils. Combination of these homologues with complete n-alkane patterns (C17-36) and OEP enabled further differentiation, while n-alcohols patterns were less distinct. Current limitation is the lack of extended and diverse quantitative records on biomarker patterns, especially for n-alcohols, non-leaf and belowground tissues, which hindered full statistical analysis. On species level we also recognized outliers and spreading. Systematic variation was indicated among tree species according to spatial conditions and by ontogeny. Yet, observed effects were ambiguous for other variation sources. This study highlights clear opportunities for application of biomarker patterns for source identification and elucidation of stabilization processes in (plaggen) soils. At the same time, application is challenged by systematic variation. Further research is key to quantify controls, magnitude and potential correction factors for such systematic variation. This would validate the use of n-alkane and n-alcohol patterns across broad spatial and temporal scales or identify boundaries wherein their consistency is ensured. Likely, these challenges apply to vegetation in a broad perspective, transcending plaggen vegetation, as assessment and application of present-day vegetation patterns is emerging.

Identifying areas of basin-floor recharge in the Trans-Pecos region and the link to vegetation

USGS Publications Warehouse

Walvoord, Michelle Ann; Phillips, Fred M.

2004-01-01

Comparative water potential and chloride profiles (∼10 m deep) collected from four vegetation communities in the Trans-Pecos region of the Chihuahuan Desert were assessed to evaluate the potential for using vegetation patterns as a means of efficiently improving large-scale estimates of basin-floor recharge in semiarid and arid regions. Analytical solutions and multiphase flow and transport modeling constrained flux histories and current fluxes across the water table at each site. Chloride bulge profiles containing ∼12–15 kyr of atmospheric deposition and long-term drying water potential profiles typified most desertscrub and grassland sites. In contrast, evidence of episodic sub-root zone percolation and chloride profiles containing <250 yr of atmospheric deposition characterized the woodland site. The results suggested that the desertscrub and grassland areas support small upward fluxes across the water table (nonrecharge), whereas the woodland site supports significant downward fluxes across the water table (recharge). A nonrecharge–recharge transition was identified to be collocated with a grassland–woodland ecotone. The establishment of vegetation–recharge relationships such as this will improve estimates of basin-scale recharge by identifying regions where no recharge is expected and regions where recharge is expected and point measurements should be concentrated. An approach integrating remotely sensed spatial distributions of vegetation and indicator relationships to recharge is both timely and warranted, although several caveats, as revealed in this study, should be noted. For example, the relative importance and distribution of vertical conduits that permit percolation to the water table merits future investigation.

Hydrologic Response to Climatic and Vegetation Change in an Extreme Alpine Environment

NASA Astrophysics Data System (ADS)

Livneh, B.; Badger, A.; Molotch, N. P.; Bueno de Mesquita, C.; Suding, K.

2016-12-01

Mountain hydrology and ecology are uniquely sensitive to climate change. This presentation will examine how changes in climate have altered land cover and hydrology in the Green Lakes Valley, an alpine catchment for which approximately 80% of the annual precipitation ( 950 mm/yr) falls as snow. In these environments vegetation has two way interaction with hydrology: its distribution is driven by patterns of snowpack and water availability while it functions to modulate hydrologic responses by alterating land-atmosphere interaction. Long-term climate trends indicate warming, earlier snowmelt, and longer snow-free growing seasons. High-resolution aerial photography from 1972 and 2008 identified vegetation encroachment as shrubs and trees have increased in vigor and density in the tundra, while herbaceous tundra plants have colonized high-elevation bare ground. To understand modulations to physical hydrology from climate and biophysical responses, we apply a 20-m resolution fully-distributed hydrologic model. Through the use of observed meteorology (radiation, humidity, temperature and precipitation) an hourly climatology was created. Realizations from a stochastic ensemble of this climatology together with trends from long-term observations are used to characterize historical hydrologic response and project future changes. Through temperature and precipitation change experiments, alterations to the annual water cycle are presented—indicating the importance of annual snowpack evolution on both the surface and sub-surface hydrology, particularly through seasonal water storage. Probabilistic land cover change scenarios are developed that project how further vegetation encroachment modulates surface water fluxes and sediment yields. Lastly, the context of these results are compared with hydrometeorological research from other differing alpine and ecological regions.

Impacts of Climate Anomalies on the Vegetation Patterns in the Arid and Semi-Arid Zones of Uzbekistan

NASA Astrophysics Data System (ADS)

Dildora, Aralova; Toderich, Kristina; Dilshod, Gafurov

2016-08-01

Steadily rising temperature anomalies in last decades are causing changes in vegetation patterns for sensitive to climate change in arid and semi-arid dryland ecosystems. After desiccation of the Aral Sea, Uzbekistan has been left with the challenge to develop drought and heat stress monitoring system and tools (e.g., to monitor vegetation status and/crop pattern dynamics) with using remote sensing technologies in broad scale. This study examines several climate parameters, NDVI and drought indexes within geostatistical method to predict further vegetation status in arid and semi-arid zones of landscapes. This approaches aimed to extract and utilize certain variable environmental data (temperature and precipitation) for assessment and inter-linkages of vegetation cover dynamics, specifically related to predict degraded and recovered zones or desertification process in the drylands due to scarcity of water resources and high risks of climate anomalies in fragile ecosystem of Uzbekistan.

Flow Field and Nutrient Dynamics Control Over Formation of Parallel Vegetation Patterns in the Florida Everglades

NASA Astrophysics Data System (ADS)

Engel, V.; Cheng, Y.; Stieglitz, M.

2009-12-01

Pattern formation in vegetated communities reflects the underlying mechanisms governing resource utilization and distribution across the landscape. An example of a patterned ecosystem is the Florida Everglades, which is characterized by parallel and slightly elevated peat "ridges" separated by deeper water "slough" communities (R&S). Ridges are dominated by sawgrass (Cladium jamaiscence). These patterns are thought to be aligned with and develop in response to the historic surface water flow direction, though the precise mechanisms which lead to their formation are poorly understood. Over the years this R&S habitat has degraded in areas where the natural flow regime, hydroperiod, and water depths have been impacted by human development. Managing and restoring this habitat has been an objective of the U.S. Federal and Florida State governments since the Comprehensive Everglades Restoration Plan (CERP) was authorized in 2000. It is imperative, however, to develop a mechanistic understanding of ridge-slough formation before the potential benefits of hydrologic forecasts associated with CERP can be evaluated. Recently, Cheng et al (see Cheng et al, session NG14) employed a simple 2D advection-diffusion model developed by Rietkerk et al (2004) to describe for the first time, the formation of parallel stripes from hydrologic interactions. To simulate parallel stripes, Cheng et al retained the basic equations of the Rietkerk model but allowed for constant advection of water and nutrient in one direction to simulate slope conditions, with evapotranspiration driven advection of water and nutrient perpendicular to the downhill flow direction. We employ this modeling framework and parameterize the model with Everglades field data to simulate ridge-slough formation. In this model, the relatively higher rates of evapotranspiration on the ridges compared to the sloughs create hydraulic gradients which carry dissolved nutrients from the sloughs to the faster growing ridges. With time, the patches aggregate and spread laterally in the direction of the downhill flow. The characteristic wavelengths and spatial patterning of the ridge-slough habitat found in the historic Everglades is reproduced by the model. Nutrient distributions across the landscape and across the ridge-slough interfaces also match observations. Perturbations to the system are modeled in the form of altered hydraulic gradients and nutrient input functions, similar to actual stressors on the system. Under the altered conditions, a loss of patterning in the habitat is observed, in some cases leading to ridge expansion into the sloughs, and in others leading to a complete loss of vegetation pattern. Simulations indicate that the hydrologic changes required to regenerate coherence in the ridge slough patterns in degraded areas are different from those in which the system originally formed. Plant-nutrient interactions and the overall nutrient status are shown to be a major determinant in how the system will respond to hydrologic changes associated with CERP.

Trends in landscape and vegetation change and implications for the Santa Cruz Watershed

USGS Publications Warehouse

Villarreal, Miguel; Norman, Laura M.; Webb, Robert H.; Turner, Raymond M.

2013-01-01

Monitoring and characterizing the interactive effects of land use and climate on land surface processes is a primary focus of land change science, and of particular concern in arid Wells Distribution in Shallow Groundwater Areas Pumping Trends Increase Streamflow Extent Declines 27 environments where both landscapes and livelihoods can be impacted by short-term climate variability. Using a multi-observational approach to land-change analysis that included landownership data as a proxy for land-use practices, multitemporal land-cover maps, and repeat photography dating to the late 19th century, we examine changing spatial and temporal distributions of two vegetation types with high conservation value in the southwestern United States: grasslands and riparian vegetation. Our study area is the bi-national Santa Cruz Watershed, a topographically complex watershed that straddles the Sonoran Desert and the Madrean Archipelago Ecoregions. In this presentation we focus on historical changes in vegetation and land use in grasslands and riparian areas of the Madrean Ecoregion (San Raphael Valley, Cienega Creek, Sonoita), and compare changes in these areas to changes in the warmer and drier Sonoran Ecoregion. Analysis of historical photography confirms major 20th century vegetation shifts documented in other research: woody plant encroachment, desertification of grasslands, and changing riparian and xeroriparian vegetation occurred in both ecoregions following human settlement. However, vegetation changes over the past decade appear to be more subtle and some of the past trajectories appear to be reversing; most notable are recent mesquite declines in xeroriparian and upland areas, and changes from shrubland to grassland area in the Madrean ecoregion. Land cover changes were temporally variable, reflecting broad climate changes. The most dynamic cover changes occurred during the period from 1989 to 1999, a period with two intense droughts. The degree of vegetation change driven by climate was related to topographic setting: vegetation declines were greater per unit area in the lower elevation Sonoran ecoregion where temperatures are higher and precipitation lower than in the Madrean. Fine-scale changes within these broad climate patterns were likely the result of land use practices: declines were highest on state lands (grazing) and increases highest on private ranches and some federal lands (active mesquite removal and watershed restoration).

Meteorological factors associated with abundance of airborne fungal spores over natural vegetation

NASA Astrophysics Data System (ADS)

Crandall, Sharifa G.; Gilbert, Gregory S.

2017-08-01

The abundance of airborne fungal spores in agricultural and urban settings increases with greater air temperature, relative humidity, or precipitation. The same meteorological factors that affect temporal patterns in spore abundance in managed environments also vary spatially across natural habitats in association with differences in vegetation structure. Here we investigated how temporal and spatial variation in aerial spore abundance is affected by abiotic (weather) and biotic (vegetation) factors as a foundation for predicting how fungi may respond to changes in weather and land-use patterns. We measured the phenology of airborne fungal spores across a mosaic of naturally occurring vegetation types at different time scales to describe (1) how spore abundance changes over time, (2) which local meteorological variables are good predictors for airborne spore density, and (3) whether spore abundance differs across vegetation types. Using an air volumetric vacuum sampler, we collected spore samples at 3-h intervals over a 120-h period in a mixed-evergreen forest and coastal prairie to measure diurnal, nocturnal, and total airborne spore abundance across vegetation types. Spore samples were also collected at weekly and monthly intervals in mixed-evergreen forest, redwood forest, and maritime chaparral vegetation types from 12 field sites across two years. We found greater airborne spore densities during the wetter winter months compared to the drier summer months. Mean total spore abundance in the mixed-evergreen forest was twice than in the coastal prairie, but there were no significant differences in total airborne spore abundance among mixed-evergreen forest, redwood forest, and maritime chaparral vegetation types. Weekly and monthly peaks in airborne spore abundance corresponded with rain events and peaks in soil moisture. Overall, temporal patterns in meteorological factors were much more important in determining airborne fungal spore abundance than the vegetation type. This suggests that overall patterns of fungal spore dynamics may be predictable across heterogeneous landscapes based on local weather patterns.

Distribution of tabanids (Diptera: Tabanidae) along a two-sided altitudinal transect.

PubMed

Hackenberger, Branimir K; Jarić, Davorka; Krcmar, Stjepan

2009-12-01

The pattern of horse fly (Diptera: Tabanidae) distribution and correlations among biodiversity, abundance, abiotic factors, and altitude were determined along a two-sided altitudinal transect. The sampling was carried out on five 3-d periods during tabanid seasonal activity. Linen canopy traps with 1-octen-3-ol as an attractant were used at 20 sampling sites along the transect. The results showed that the qualitative composition of tabanid species can be distinguished by altitude and, especially, between southeastern and northwestern mountain slopes. The peaks of horse fly species richness and abundance were indicated at middle elevations of both slopes, where horse fly distributional groups were overlapping and most rare and infrequent species were sampled. All expected species were sampled according to species accumulation curve. The canonical correlation analysis separated species and sampling sites into three clusters; two were positively correlated with the temperature and the wind but differed in sensitivity toward them, and the third cluster was correlated with the humidity. The horse fly distribution was nonhomogenous, and the distributional patterns were only partially determined by altitude and vegetation. The determining environmental variables were different for each slope: temperature and wind for the southern slope (Mediterranean climatic zone) and humidity for the northern slope (continental climatic zone).

Survey of remote sensing applications

USGS Publications Warehouse

Deutsch, Morris

1974-01-01

Data from the first earth resources technology satellite (ERTS) as well as from NASA and other aircraft, contain much of the information indicative of the distribution of groundwater and the extent of its utilization. Thermal infrared imagery from aircraft is particularly valuable in studying groundwater discharge to the sea and other surface water bodies. Color infrared photography from aircraft and space is also used to locate areas of potential groundwater development. Anomalies in vegetation, soils, moisture, and their pattern of distribution may be indicative of underlying groundwater conditions. Remote sensing may be used directly or indirectly to identify stream reaches for test holes or production wells. Similarly, location of submarine springs increase effectiveness of groundwater exploration in the coastal zone.

Applications for predicting precipitation and vegetation patterns at landscape scale using lightning strike data

Treesearch

Deborah Ulinski Potter

1999-01-01

Previous publications discussed the results of my dissertation research on relationships between seasonality in precipitation and vegetation patterns at landscape scale. Summer precipitation at a study site in the Zuni Mountains, NM, was predicted from lightning strike and relative humidity data using multiple regression. Summer precipitation patterns were mapped using...

Comparison modeling for alpine vegetation distribution in an arid area.

PubMed

Zhou, Jihua; Lai, Liming; Guan, Tianyu; Cai, Wetao; Gao, Nannan; Zhang, Xiaolong; Yang, Dawen; Cong, Zhentao; Zheng, Yuanrun

2016-07-01

Mapping and modeling vegetation distribution are fundamental topics in vegetation ecology. With the rise of powerful new statistical techniques and GIS tools, the development of predictive vegetation distribution models has increased rapidly. However, modeling alpine vegetation with high accuracy in arid areas is still a challenge because of the complexity and heterogeneity of the environment. Here, we used a set of 70 variables from ASTER GDEM, WorldClim, and Landsat-8 OLI (land surface albedo and spectral vegetation indices) data with decision tree (DT), maximum likelihood classification (MLC), and random forest (RF) models to discriminate the eight vegetation groups and 19 vegetation formations in the upper reaches of the Heihe River Basin in the Qilian Mountains, northwest China. The combination of variables clearly discriminated vegetation groups but failed to discriminate vegetation formations. Different variable combinations performed differently in each type of model, but the most consistently important parameter in alpine vegetation modeling was elevation. The best RF model was more accurate for vegetation modeling compared with the DT and MLC models for this alpine region, with an overall accuracy of 75 % and a kappa coefficient of 0.64 verified against field point data and an overall accuracy of 65 % and a kappa of 0.52 verified against vegetation map data. The accuracy of regional vegetation modeling differed depending on the variable combinations and models, resulting in different classifications for specific vegetation groups.

Soil nutrient-landscape relationships in a lowland tropical rainforest in Panama

USGS Publications Warehouse

Barthold, F.K.; Stallard, R.F.; Elsenbeer, H.

2008-01-01

Soils play a crucial role in biogeochemical cycles as spatially distributed sources and sinks of nutrients. Any spatial patterns depend on soil forming processes, our understanding of which is still limited, especially in regards to tropical rainforests. The objective of our study was to investigate the effects of landscape properties, with an emphasis on the geometry of the land surface, on the spatial heterogeneity of soil chemical properties, and to test the suitability of soil-landscape modeling as an appropriate technique to predict the spatial variability of exchangeable K and Mg in a humid tropical forest in Panama. We used a design-based, stratified sampling scheme to collect soil samples at 108 sites on Barro Colorado Island, Panama. Stratifying variables are lithology, vegetation and topography. Topographic variables were generated from high-resolution digital elevation models with a grid size of 5 m. We took samples from five depths down to 1 m, and analyzed for total and exchangeable K and Mg. We used simple explorative data analysis techniques to elucidate the importance of lithology for soil total and exchangeable K and Mg. Classification and Regression Trees (CART) were adopted to investigate importance of topography, lithology and vegetation for the spatial distribution of exchangeable K and Mg and with the intention to develop models that regionalize the point observations using digital terrain data as explanatory variables. Our results suggest that topography and vegetation do not control the spatial distribution of the selected soil chemical properties at a landscape scale and lithology is important to some degree. Exchangeable K is distributed equally across the study area indicating that other than landscape processes, e.g. biogeochemical processes, are responsible for its spatial distribution. Lithology contributes to the spatial variation of exchangeable Mg but controlling variables could not be detected. The spatial variation of soil total K and Mg is mainly influenced by lithology. ?? 2007 Elsevier B.V. All rights reserved.

Brackish marsh zones as a waterfowl habitat resource in submerged aquatic vegetation beds in the northern Gulf of Mexico

USGS Publications Warehouse

DeMarco, Kristin; Hillmann, Eva R.; Brasher, Michael G.; LaPeyre, Megan K.

2016-01-01

Submerged aquatic vegetation (SAV) beds are shallow coastal habitats that are increasingly exposed to the effects of sea-level rise (SLR). In the northern Gulf of Mexico (nGoM), an area especially vulnerable to SLR, the abundance and distribution of SAV food resources (seeds, rhizomes, and tissue) can influence the carrying capacity of coastal marshes to support wintering waterfowl. Despite the known importance of SAV little is known about their distribution across coastal landscapes and salinity zones or how they may be impacted by SLR. We estimated SAV cover and seed biomass in coastal marshes from Texas to Alabama from 1 June – 15 September 2013 to assess variation in SAV and seed resource distribution and abundance across the salinity gradient. Percent cover of SAV was similar among salinity zones (10%–20%) although patterns of distribution differed. Specifically, SAV occurred less frequently in saline zones, but when present the percent coverage was greater than in fresh, intermediate and brackish. Mean seed biomass varied greatly and did not differ significantly among salinity zones. However, when considering only seed species identified as waterfowl foods, the mean seed biomass was lower in saline zones (1.2 g m–2). Alteration of nGoM marshes due to SLR will likely shift the distribution and abundance of SAV resources, and these shifts may affect carrying capacity of coastal marshes for waterfowl and other associated species.

Shallow landsliding, root reinforcement, and the spatial distribution of trees in the Oregon Coast Range

USGS Publications Warehouse

Roering, J.J.; Schmidt, K.M.; Stock, J.D.; Dietrich, W.E.; Montgomery, D.R.

2003-01-01

The influence of root reinforcement on shallow landsliding has been well established through mechanistic and empirical studies, yet few studies have examined how local vegetative patterns influence slope stability. Because root networks spread outward from trees, the species, size, and spacing of trees should influence the spatial distribution of root strength. We documented the distribution and characteristics of trees adjacent to 32 shallow landslides that occurred during 1996 in the Oregon Coast Range. Although broadly classified as a conifer-dominated forest, we observed sparse coniferous and abundant hardwood trees near landslide scars in an industrial forest (Mapleton) that experienced widespread burning in the 19th century. In industrial forests that were burned, selectively harvested, and not replanted (Elliott State Forest), swordfern was ubiquitous near landslides, and we observed similar numbers of live conifer and hardwood trees proximal to landslide scarps. We demonstrate that root strength quantified in landslide scarps and soil pits correlates with a geometry-based index of root network contribution derived from mapping the size, species, condition, and spacing of local trees, indicating that root strength can be predicted by mapping the distribution and characteristics of trees on potentially unstable slopes. In our study sites, landslides tend to occur in areas of reduced root strength, suggesting that to make site-specific predictions of landslide occurrence slope stability analyses must account for the diversity and distribution of vegetation in potentially unstable terrain.

Food patterns of Australian children ages 9 to 13 y in relation to ω-3 long chain polyunsaturated intake.

PubMed

Rahmawaty, Setyaningrum; Lyons-Wall, Philippa; Batterham, Marijka; Charlton, Karen; Meyer, Barbara J

2014-02-01

The aim of this study was to examine food patterns of Australian children ages 9 to 13 y in relation to ω-3 long-chain polyunsaturated fatty acid (ω-3 LCPUFA) intake. Secondary analysis was conducted on nationally representative food data of 1110 Australian children ages 9 to 13 y (525 boys and 585 girls) that was obtained using two 24-h recalls. Principle component factor analysis was used to identify food patterns. Discriminant function analysis was used to identify the relationship between the food patterns and total ω-3 LCPUFA intake. Four major food patterns emerged for each sex. For boys these were labeled: "snack foods," "soft drinks," "vegetables," and "pork and meat chops, steak, and mince." For girls they were labeled: "vegetables," "take-away," "tea, coffee, iced coffee drinks" and "canned meals and soup." Fish consumption bought from take-away outlets was more frequently consumed in the "soft drink" (r = 0.577) and take-away (r = 0.485) food pattern in boys and girls, respectively. In contrast, fish prepared at home was more often consumed in "vegetables" in both boys (r = 0.018) and girls (r = 0.106), as well as in the "pork and meat chops, steak and mince" food pattern in boys (r = 0.060). There was a trend that in boys, the "vegetables" group discriminated children who consumed ω-3 LCPUFA levels similar to adequate intakes (AI) (P = 0.067), whereas in girls, the take-away food pattern discriminated for being a fish consumer (P = 0.060). Dietary patterns associated with a high consumption of vegetables and "take-aways" food that include meat and fish are likely to positively influence dietary ω-3 LCPUFA intake in Australian children. Copyright © 2014 Elsevier Inc. All rights reserved.

A fully traits-based approach to modeling global vegetation distribution.

PubMed

van Bodegom, Peter M; Douma, Jacob C; Verheijen, Lieneke M

2014-09-23

Dynamic Global Vegetation Models (DGVMs) are indispensable for our understanding of climate change impacts. The application of traits in DGVMs is increasingly refined. However, a comprehensive analysis of the direct impacts of trait variation on global vegetation distribution does not yet exist. Here, we present such analysis as proof of principle. We run regressions of trait observations for leaf mass per area, stem-specific density, and seed mass from a global database against multiple environmental drivers, making use of findings of global trait convergence. This analysis explained up to 52% of the global variation of traits. Global trait maps, generated by coupling the regression equations to gridded soil and climate maps, showed up to orders of magnitude variation in trait values. Subsequently, nine vegetation types were characterized by the trait combinations that they possess using Gaussian mixture density functions. The trait maps were input to these functions to determine global occurrence probabilities for each vegetation type. We prepared vegetation maps, assuming that the most probable (and thus, most suited) vegetation type at each location will be realized. This fully traits-based vegetation map predicted 42% of the observed vegetation distribution correctly. Our results indicate that a major proportion of the predictive ability of DGVMs with respect to vegetation distribution can be attained by three traits alone if traits like stem-specific density and seed mass are included. We envision that our traits-based approach, our observation-driven trait maps, and our vegetation maps may inspire a new generation of powerful traits-based DGVMs.

Classification of vegetation in an open landscape using full-waveform airborne laser scanner data

NASA Astrophysics Data System (ADS)

Alexander, Cici; Deák, Balázs; Kania, Adam; Mücke, Werner; Heilmeier, Hermann

2015-09-01

Airborne laser scanning (ALS) is increasingly being used for the mapping of vegetation, although the focus so far has been on woody vegetation, and ALS data have only rarely been used for the classification of grassland vegetation. In this study, we classified the vegetation of an open alkali landscape, characterized by two Natura 2000 habitat types: Pannonic salt steppes and salt marshes and Pannonic loess steppic grasslands. We generated 18 variables from an ALS dataset collected in the growing (leaf-on) season. Elevation is a key factor determining the patterns of vegetation types in the landscape, and hence 3 additional variables were based on a digital terrain model (DTM) generated from an ALS dataset collected in the dormant (leaf-off) season. We classified the vegetation into 24 classes based on these 21 variables, at a pixel size of 1 m. Two groups of variables with and without the DTM-based variables were used in a Random Forest classifier, to estimate the influence of elevation, on the accuracy of the classification. The resulting classes at Level 4, based on associations, were aggregated at three levels - Level 3 (11 classes), Level 2 (8 classes) and Level 1 (5 classes) - based on species pool, site conditions and structure, and the accuracies were assessed. The classes were also aggregated based on Natura 2000 habitat types to assess the accuracy of the classification, and its usefulness for the monitoring of habitat quality. The vegetation could be classified into dry grasslands, wetlands, weeds, woody species and man-made features, at Level 1, with an accuracy of 0.79 (Cohen's kappa coefficient, κ). The accuracies at Levels 2-4 and the classification based on the Natura 2000 habitat types were κ: 0.76, 0.61, 0.51 and 0.69, respectively. Levels 1 and 2 provide suitable information for nature conservationists and land managers, while Levels 3 and 4 are especially useful for ecologists, geologists and soil scientists as they provide high resolution data on species distribution, vegetation patterns, soil properties and on their correlations. Including the DTM-based variables increased the accuracy (κ) from 0.73 to 0.79 for Level 1. These findings show that the structural and spectral attributes of ALS echoes can be used for the classification of open landscapes, especially those where vegetation is influenced by elevation, such as coastal salt marshes, sand dunes, karst or alluvial areas; in these cases, ALS has a distinct advantage over other remotely sensed data.

Vegetation cover in relation to socioeconomic factors in a tropical city assessed from sub-meter resolution imagery.

PubMed

Martinuzzi, Sebastián; Ramos-González, Olga M; Muñoz-Erickson, Tischa A; Locke, Dexter H; Lugo, Ariel E; Radeloff, Volker C

2018-04-01

Fine-scale information about urban vegetation and social-ecological relationships is crucial to inform both urban planning and ecological research, and high spatial resolution imagery is a valuable tool for assessing urban areas. However, urban ecology and remote sensing have largely focused on cities in temperate zones. Our goal was to characterize urban vegetation cover with sub-meter (<1 m) resolution aerial imagery, and identify social-ecological relationships of urban vegetation patterns in a tropical city, the San Juan Metropolitan Area, Puerto Rico. Our specific objectives were to (1) map vegetation cover using sub-meter spatial resolution (0.3-m) imagery, (2) quantify the amount of residential and non-residential vegetation, and (3) investigate the relationship between patterns of urban vegetation vs. socioeconomic and environmental factors. We found that 61% of the San Juan Metropolitan Area was green and that our combination of high spatial resolution imagery and object-based classification was highly successful for extracting vegetation cover in a moist tropical city (97% accuracy). In addition, simple spatial pattern analysis allowed us to separate residential from non-residential vegetation with 76% accuracy, and patterns of residential and non-residential vegetation varied greatly across the city. Both socioeconomic (e.g., population density, building age, detached homes) and environmental variables (e.g., topography) were important in explaining variations in vegetation cover in our spatial regression models. However, important socioeconomic drivers found in cities in temperate zones, such as income and home value, were not important in San Juan. Climatic and cultural differences between tropical and temperate cities may result in different social-ecological relationships. Our study provides novel information for local land use planners, highlights the value of high spatial resolution remote sensing data to advance ecological research and urban planning in tropical cities, and emphasizes the need for more studies in tropical cities. © 2017 by the Ecological Society of America.

How vegetation and sediment transport feedbacks drive landscape change in the Everglades and wetlands worldwide

USGS Publications Warehouse

Larsen, Laurel G.; Harvey, Judson W.

2010-01-01

Mechanisms reported to promote landscape self‐organization cannot explain vegetation patterning oriented parallel to flow. Recent catastrophic shifts in Everglades landscape pattern and ecological function highlight the need to understand the feedbacks governing these ecosystems. We modeled feedback between vegetation, hydrology, and sediment transport on the basis of a decade of experimentation. Results from more than 100 simulations showed that flows just sufficient to redistribute sediment from sparsely vegetated sloughs to dense ridges were needed for an equilibrium patterned landscape oriented parallel to flow. Surprisingly, although vegetation heterogeneity typically conveys resilience, in wetlands governed by flow/sediment feedbacks it indicates metastability, whereby the landscape is prone to catastrophic shifts. Substantial increases or decreases in flow relative to the equilibrium condition caused an expansion of emergent vegetation and loss of open‐water areas that was unlikely to revert upon restoration of the equilibrium hydrology. Understanding these feedbacks is critical in forecasting wetland responses to changing conditions and designing management strategies that optimize ecosystem services, such as carbon sequestration or habitat provision. Our model and new sensitivity analysis techniques address these issues and make it newly apparent that simply returning flow to predrainage conditions in the Everglades may not be sufficient to restore historic landscape patterns and processes.

Analysis of Post-Fire Vegetation Recovery in the Mediterranean Basin using MODIS Derived Vegetation Indices

NASA Astrophysics Data System (ADS)

Hawtree, Daniel; San Miguel, Jesus; Sedano, Fernando; Kempeneers, Pieter

2010-05-01

The Mediterranean basin region is highly susceptible to wildfire, with approximately 60,000 individual fires and half a million ha of natural vegetation burnt per year. Of particular concern in this region is the impact of repeated wildfires on the ability of natural lands to return to a pre-fire state, and of the possibility of desertification of semi-arid areas. Given these concerns, understanding the temporal patterns of vegetation recovery is important for the management of environmental resources in the region. A valuable tool for evaluating these recovery patterns are vegetation indices derived from remote sensing data. Previous research on post-fire vegetation recovery conducted in this region has found significant variability in recovery times across different study sites. It is unclear what the primary variables are affecting the differences in the rates of recovery, and if any geographic patterns of behavior exist across the Mediterranean basin. This research has primarily been conducted using indices derived from Landsat imagery. However, no extensive analysis of vegetation regeneration for large regions has been published, and assessment of vegetation recovery on the basis of medium-spatial resolution imagery such as that of MODIS has not yet been analyzed. This study examines the temporal pattern of vegetation recovery in a number of fire sites in the Mediterranean basin, using data derived from MODIS 16 -day composite vegetation indices. The intent is to develop a more complete picture of the temporal sequence of vegetation recovery, and to evaluate what additional factors impact variations in the recovery sequence. In addition, this study evaluates the utility of using MODIS derived vegetation indices for regeneration studies, and compares the findings to earlier studies which rely on Landsat data. Wildfires occurring between the years 2000 and 2004 were considered as potential study sites for this research. Using the EFFIS dataset, all wildfires covering an area of at least 1,000 ha were identified. The land-cover / land-use of these large fires sites were then evaluated using the CORINE land-cover data set, and the sites dominated primarily by natural vegetation were identified. Once these candidate sites were identified, a subset was selected across a range of locations and site characteristics for post-fire recovery analysis. To evaluate the post-fire recovery sequence in these locations, time-series of NDVI, EVI, and LAI were derived using 250 meter resolution MODIS data (MOD13Q). The vegetation index values were then compared to pre-fire values to determine recovery relative to the pre-fire vegetative state. The variability in rates of recovery are then considered with respect to moisture availability, vegetation type, and local site conditions to evaluate if any patterns of recovery can be determined.

Development of population structure and spatial distribution patterns of a restored forest during 17-year succession (1993-2010) in Pingshuo opencast mine spoil, China.

PubMed

Zhao, Zhongqiu; Wang, Lianhua; Bai, Zhongke; Pan, Ziguan; Wang, Yun

2015-07-01

Afforestation of native tree species is often recommended for ecological restoration in mining areas, but the understanding of the ecological processes of restored vegetation is quite limited. In order to provide insight of the ecological processes of restored vegetation, in this study, we investigate the development of the population structure and spatial distribution patterns of restored Robinia pseudoacacia (ROPS) and Pinus tabuliformis (PITA) mixed forests during the 17 years of the mine spoil period of the Pingshuo opencast mine, Shanxi Province, China. After a 17-year succession, apart from the two planted species, Ulmus pumila (ULPU), as an invasive species, settled in the plot along with a large number of small diameter at breast height (DBH) size. In total, there are 10,062 living individual plants, much more than that at the plantation (5105), and ROPS had become the dominant species with a section area with a breast height of 9.40 m(2) hm(-2) and a mean DBH of 6.72 cm, much higher than both PITA and ULPU. The DBH size classes of all the total species showed inverted J-shaped distributions, which may have been a result of the large number of small regenerated ULPU trees. The DBH size classes of both ROPS and PITA showed peak-type structures with individuals mainly gathering in the moderate DBH size class, indicating a relatively healthy DBH size class structure. Meanwhile, invasive ULPU were distributed in a clear L shape, concentrating on the small DBH size class, indicating a relatively low survival rate for adult trees. Both ROPS and PITA species survival in the plantation showed uniform and aggregated distribution at small scales and random with scales increasing. ULPU showed a strong aggregation at small scales as well as random with scales increasing. Both the population structure and spatial distribution indicated that ROPS dominates and will continue to dominate the community in the future succession, which should be continuously monitored.

Interactions between Hillslope Hydraulic Response Function, Vegetation Organisation and Catchment Behaviour

NASA Astrophysics Data System (ADS)

Schymanski, Stanislaus J.; McDonnell, Jeffrey; Or, Dani

2013-04-01

The behaviour of a catchment is sensitive to the pattern and organisation of its components (hillslopes, land cover etc.). Explaining observed organisation and emergence of pattern requires understanding of key organising principles, recognising that albeit similarities, the larger scale behaviour is likely to differ from that of individual components. In other words, the whole does not necessarily behave like the sum of its parts, because the arrangement of the parts matters. For example, hillslopes involve complex and hydrologically interacting elements (rapid flow pathways, depression storage, slope, and variable soil thickness) that shape hillslope hydrologic response in ways that cannot be represented by a collection of pores as implied by standard hydraulic functions. Additionally, inherent spatial and temporal variability of vegetation prohibits detailed and mechanistic parameterisation of root water uptake and evapotranspiration. The interplay of hydrologic hillslope function, climatic forcing and vegetation dynamics translates into complex catchment behaviour at the outlet. Vegetation, one of the most dynamic determinants of catchment behaviour, may interact with its environment by varying different elements such as root system properties, foliage properties and spatial arrangement. These interactions span different temporal scales from minutes (stomatal conductance) to decades (spatial arrangement) all of which may shape evapotranspiration and hence catchment behaviour. Evidence suggests that vegetation adapts to its environment in a self-organised, predictable way, guided by some overarching goal function, such as maximum net carbon profit or maximum entropy production. Appropriate optimality considerations under prevailing constraints enabled predictions of spatial heterogeneity of vegetation cover, or temporal dynamics of root distribution, canopy properties and water use. The hydrologic hillslope behaviour (e.g., surface and subsurface water fluxes and storage) is a powerful ingredient that defines boundary conditions for vegetation self-organisation. To systematically evaluate the role of this element, we propose a Hillslope Hydraulic Response Function (HHRF) a standardised parameterisation framework based on simplified and analytical representation of a prototypic hillslope. The HHRF uses a few geometrical parameters and intrinsic parameters to represent hillslope response in terms of fluxes and storage dynamics. Such an approach has been instrumental in deducing hydrologic response of watersheds (Kirchner, 2009, WRR) but has not been used for systematic parameterisation of HHRF. Here we separate out the biotic and abiotic components of catchment behaviour and test the sensitivity of vegetation and the catchment water balance to different hypothetical parameterisations of the HHRF.

Power Law Patch Scaling and Lack of Characteristic Wavelength Suggest "Scale-Free" Processes Drive Pattern Formation in the Florida Everglades

NASA Astrophysics Data System (ADS)

Kaplan, D. A.; Casey, S. T.; Cohen, M. J.; Acharya, S.; Jawitz, J. W.

2016-12-01

A century of hydrologic modification has altered the physical and biological drivers of landscape processes in the Everglades (Florida, USA). Restoring the ridge-slough patterned landscape, a dominant feature of the historical system, is a priority, but requires an understanding of pattern genesis and degradation mechanisms. Physical experiments to evaluate alternative pattern formation mechanisms are limited by the long time scales of peat accumulation and loss, necessitating model-based comparisons, where support for a particular mechanism is based on model replication of extant patterning and trajectories of degradation. However, multiple mechanisms yield patch elongation in the direction of historical flow (a central feature of ridge-slough patterning), limiting the utility of that characteristic for discriminating among alternatives. Using data from vegetation maps, we investigated the statistical features of ridge-slough spatial patterning (ridge density, patch perimeter, elongation, patch-size distributions, and spatial periodicity) to establish more rigorous criteria for evaluating model performance and to inform controls on pattern variation across the contemporary system. Two independent analyses (2-D periodograms and patch size distributions) provide strong evidence against regular patterning, with the landscape exhibiting neither a characteristic wavelength nor a characteristic patch size, both of which are expected under conditions that produce regular patterns. Rather, landscape properties suggest robust scale-free patterning, indicating genesis from the coupled effects of local facilitation and a global negative feedback operating uniformly at the landscape-scale. This finding challenges widespread invocation of scale-dependent negative feedbacks for explaining ridge-slough pattern origins. These results help discern among genesis mechanisms and provide an improved statistical description of the landscape that can be used to compare among model outputs, as well as to assess the success of future restoration projects.

Ground-Vegetation Clutter Affects Phyllostomid Bat Assemblage Structure in Lowland Amazonian Forest

PubMed Central

Marciente, Rodrigo; Bobrowiec, Paulo Estefano D.; Magnusson, William E.

2015-01-01

Vegetation clutter is a limiting factor for bats that forage near ground level, and may determine the distribution of species and guilds. However, many studies that evaluated the effects of vegetation clutter on bats have used qualitative descriptions rather than direct measurements of vegetation density. Moreover, few studies have evaluated the effect of vegetation clutter on a regional scale. Here, we evaluate the influence of the physical obstruction of vegetation on phyllostomid-bat assemblages along a 520 km transect in continuous Amazonian forest. We sampled bats using mist nets in eight localities during 80 nights (3840 net-hours) and estimated the ground-vegetation density with digital photographs. The total number of species, number of animalivorous species, total number of frugivorous species, number of understory frugivorous species, and abundance of canopy frugivorous bats were negatively associated with vegetation clutter. The bat assemblages showed a nested structure in relation to degree of clutter, with animalivorous and understory frugivorous bats distributed throughout the vegetation-clutter gradient, while canopy frugivores were restricted to sites with more open vegetation. The species distribution along the gradient of vegetation clutter was not closely associated with wing morphology, but aspect ratio and wing load differed between frugivores and animalivores. Vegetation structure plays an important role in structuring assemblages of the bats at the regional scale by increasing beta diversity between sites. Differences in foraging strategy and diet of the guilds seem to have contributed more to the spatial distribution of bats than the wing characteristics of the species alone. PMID:26066654

From Patterns to Function in Living Systems: Dryland Ecosystems as a Case Study

NASA Astrophysics Data System (ADS)

Meron, Ehud

2018-03-01

Spatial patterns are ubiquitous in animate matter. Besides their intricate structure and beauty they generally play functional roles. The capacity of living systems to remain functional in changing environments is a question of utmost importance, but its intimate relationship to pattern formation is largely unexplored. Here, we address this relationship using dryland vegetation as a case study. Following a brief introduction to pattern-formation theory, we describe a mathematical model that captures several mechanisms of vegetation pattern formation and discuss ecological contexts that showcase different mechanisms. Using this model, we unravel the different vegetation patterns that keep dryland ecosystems viable along the rainfall gradient, identify multistability ranges where fronts separating domains of alternative stable states exist, and highlight the roles of front dynamics in mitigating or reversing desertification. The utility of satellite images in testing model predictions is discussed. An outlook on outstanding open problems concludes this paper.

Elevation Control on Vegetation Organization in a Semiarid Ecosystem in Central New Mexico

NASA Astrophysics Data System (ADS)

Nudurupati, S. S.; Istanbulluoglu, E.; Adams, J. M.; Hobley, D. E. J.; Gasparini, N. M.; Tucker, G. E.; Hutton, E. W. H.

2015-12-01

Many semiarid and desert ecosystems are characterized by patchy and dynamic vegetation. Topography plays a commanding role on vegetation patterns. It is observed that plant biomes and biodiversity vary systematically with slope and aspect, from shrublands in low desert elevations, to mixed grass/shrublands in mid elevations, and forests at high elevations. In this study, we investigate the role of elevation dependent climatology on vegetation organization in a semiarid New Mexico catchment where elevation and hillslope aspect play a defining role on plant types. An ecohydrologic cellular automaton model developed within Landlab (component based modeling framework) is used. The model couples local vegetation dynamics (that simulate biomass production based on local soil moisture and potential evapotranspiration) and plant establishment and mortality based on competition for resources and space. This model is driven by elevation dependent rainfall pulses and solar radiation. The domain is initialized with randomly assigned plant types and the model parameters that couple plant response with soil moisture are systematically changed. Climate perturbation experiments are conducted to examine spatial vegetation organization and associated timescales. Model results reproduce elevation and aspect controls on observed vegetation patterns indicating that this model captures necessary and sufficient conditions that explain these observed ecohydrological patterns.

On modeling the organization of landscapes and vegetation patterns controlled by solar radiation

NASA Astrophysics Data System (ADS)

Istanbulluoglu, E.; Yetemen, O.

2014-12-01

Solar radiation is a critical driver of ecohydrologic processes and vegetation dynamics. Patterns of runoff generation and vegetation dictate landscape geomorphic response. Distinct patterns in the organization of soil moisture, vegetation type, and landscape morphology have been documented in close relation to aspect in a range of climates. Within catchments, from north to south facing slopes, studies have shown ecotone shifts from forest to shrub species, and steep diffusion-dominated landforms to fluvial landforms. Over the long term differential evolution of ecohydrology and geomorphology leads to observed asymmetric structure in the planform of channel network and valley morphology. In this talk we present examples of coupled modeling of ecohydrology and geomorphology driven by solar radiation. In a cellular automata model of vegetation dynamics we will first show how plants organize in north and south facing slopes and how biodiversity changes with elevation. When vegetation-erosion feedbacks are coupled emergent properties of the coupled system are observed in the modeled elevation and vegetation fields. Integrating processes at a range of temporal and spatial scales, coupled models of ecohydrologic and geomorphic dynamics enable examination of global change impacts on landscapes and ecosystems.

Spatial and Temporal Distribution of Non-Biting Midge Larvae Assemblages in Streams in a Mountainous Region in Southern Brazil

PubMed Central

Floss, Elzira Cecília Serafini; Secretti, Elisangela; Kotzian, Carla Bender; Spies, Marcia Regina; Pires, Mateus Marques

2013-01-01

The spatial and temporal structure of non-biting midge (Diptera: Chironomidae) larvae assemblages and some environmental factors that affect their distribution were analyzed in a montane river and its tributaries in a temperate climate region of southernmost Brazil. In total, 69 taxa were recorded after four seasonal samplings (winter, spring, summer, and autumn). The dominant taxa were Rheotanytarsus sp. 1, Rheotanytarsus sp. 2, Cricotopus sp. 2, and Polypedilum (Polypedilum) sp., although dominance varied among the four sampling sites. The variations in dominance, abundance, and richness among the different sites were affected by environmental characteristics, such as the presence of marginal vegetation and a heterogeneous substratum, and also by human activities. Strictly environmental factors, such as altitude, and factors related to annual weather patterns, such as mean temperature and precipitation, influenced the spatial and temporal distribution of certain taxa and the structure of faunal assemblages. The influence of the riparian vegetation and riverbed heterogeneity on the composition, richness, and abundance of the chironomid larvae assemblages indicates that human activities, such as deforestation and the construction of dams, constitute a serious threat to the conservation of these insects and to the fauna that depends on them for food. PMID:24784953

[Geographic patterns and ecological factors correlates of snake species richness in China].

PubMed

Cai, Bo; Huang, Yong; Chen, Yue-Ying; Hu, Jun-Hua; Guo, Xian-Guang; Wang, Yue-Zhao

2012-08-01

Understanding large-scale geographic patterns of species richness as well its underlying mechanisms are among the most significant objectives of macroecology and biogeography. The ecological hypothesis is one of the most accepted explanations of this mechanism. Here, we studied the geographic patterns of snakes and investigated the relationships between species richness and ecological factors in China at a spatial resolution of 100 km×100 km. We obtained the eigenvector-based spatial filters by Principal Coordinates Neighbor Matrices, and then analyzed ecological factors by multiple regression analysis. The results indicated several things: (1) species richness of snakes showed multi-peak patterns along both the latitudinal and longitudinal gradient. The areas of highest richness of snake are tropics and subtropical areas of Oriental realm in China while the areas of lowest richness are Qinghai-Tibet Plateau, the grasslands and deserts in northern China, Yangtze-Huai Plain, Two-lake Plain, and the Poyang-lake Plain; (2) results of multiple regression analysis explained a total of 56.5% variance in snake richness. Among ecological factors used to explore the species richness patterns, we found the best factors were the normalized difference vegetation index, precipitation in the coldest quarter and temperature annual range ; (3) our results indicated that the model based on the significant variables that (P<0.05) uses a combination of precipitation of coldest quarter, normalized difference vegetation index and temperature annual range is the most parsimonious model for explaining the mechanism of snake richness in China. This finding demonstrates that different ecological factors work together to affect the geographic distribution of snakes in China. Studying the mechanisms that underlie these geographic patterns are complex, so we must carefully consider the choice of impact-factors and the influence of human activities.

Vehicle Routing Problem Using Genetic Algorithm with Multi Compartment on Vegetable Distribution

NASA Astrophysics Data System (ADS)

Kurnia, Hari; Gustri Wahyuni, Elyza; Cergas Pembrani, Elang; Gardini, Syifa Tri; Kurnia Aditya, Silfa

2018-03-01

The problem that is often gained by the industries of managing and distributing vegetables is how to distribute vegetables so that the quality of the vegetables can be maintained properly. The problems encountered include optimal route selection and little travel time or so-called TSP (Traveling Salesman Problem). These problems can be modeled using the Vehicle Routing Problem (VRP) algorithm with rating ranking, a cross order based crossing, and also order based mutation mutations on selected chromosomes. This study uses limitations using only 20 market points, 2 point warehouse (multi compartment) and 5 vehicles. It is determined that for one distribution, one vehicle can only distribute to 4 market points only from 1 particular warehouse, and also one such vehicle can only accommodate 100 kg capacity.

Diurnal variations of vegetation canopy structure

NASA Technical Reports Server (NTRS)

Kimes, D. S.; Kirchner, J. A.

1983-01-01

The significance and magnitude of diurnal variations of vegetation canopy structure are reviewed. Diurnal leaf inclination-azimuth angle distributions of a soybean and cotton canopy were documented using a simple measurement technique. The precision of the measurements was on the order of + or -5 deg for the inclination and + or -14 deg for the azimuth. The experimental results and a review of the literature showed that this distribution can vary significantly on a diurnal basis due to vegetation type, heliotropic leaf movement, environmental conditions, and vegetation stress. The study also showed that it is erroneous to treat two separate distributions of azimuth and inclination angles rather than one three-dimensional distribution of leaf orientation. The latter distribution needs to be routinely collected in studies which document variations of diurnal spectral reflectance with changes in solar zenith angle.

A synthesis of terrestrial mercury in the western United States: Spatial distribution defined by land cover and plant productivity.

PubMed

Obrist, Daniel; Pearson, Christopher; Webster, Jackson; Kane, Tyler; Lin, Che-Jen; Aiken, George R; Alpers, Charles N

2016-10-15

A synthesis of published vegetation mercury (Hg) data across 11 contiguous states in the western United States showed that aboveground biomass concentrations followed the order: leaves (26μgkg(-1))~branches (26μgkg(-1))>bark (16μgkg(-1))>bole wood (1μgkg(-1)). No spatial trends of Hg in aboveground biomass distribution were detected, which likely is due to very sparse data coverage and different sampling protocols. Vegetation data are largely lacking for important functional vegetation types such as shrubs, herbaceous species, and grasses. Soil concentrations collected from the published literature were high in the western United States, with 12% of observations exceeding 100μgkg(-1), reflecting a bias toward investigations in Hg-enriched sites. In contrast, soil Hg concentrations from a randomly distributed data set (1911 sampling points; Smith et al., 2013a) averaged 24μgkg(-1) (A-horizon) and 22μgkg(-1) (C-horizon), and only 2.6% of data exceeded 100μgkg(-1). Soil Hg concentrations significantly differed among land covers, following the order: forested upland>planted/cultivated>herbaceous upland/shrubland>barren soils. Concentrations in forests were on average 2.5 times higher than in barren locations. Principal component analyses showed that soil Hg concentrations were not or weakly related to modeled dry and wet Hg deposition and proximity to mining, geothermal areas, and coal-fired power plants. Soil Hg distribution also was not closely related to other trace metals, but strongly associated with organic carbon, precipitation, canopy greenness, and foliar Hg pools of overlying vegetation. These patterns indicate that soil Hg concentrations are related to atmospheric deposition and reflect an overwhelming influence of plant productivity - driven by water availability - with productive landscapes showing high soil Hg accumulation and unproductive barren soils and shrublands showing low soil Hg values. Large expanses of low-productivity, arid ecosystems across the western U.S. result in some of the lowest soil Hg concentrations observed worldwide. Copyright © 2015 Elsevier B.V. All rights reserved.

Worldwide burden of gastric cancer in 2012 that could have been prevented by increasing fruit and vegetable intake and predictions for 2025.

PubMed

Peleteiro, Bárbara; Padrão, Patrícia; Castro, Clara; Ferro, Ana; Morais, Samantha; Lunet, Nuno

2016-03-14

The regional and temporal variation in patterns of fruit and vegetable intake contributes to differences in the impact on gastric cancer burden across regions and over the years. We aimed to estimate the proportion and absolute number of gastric cancer cases that could have been prevented in 2012 with an increase in fruit and vegetable intake up to the levels defined by the Global Burden of Disease as the theoretical minimum-risk exposure distribution (300 and 400 g/d, respectively), as well as the corresponding figures expected for 2025. Preventable fractions (PF) were computed for 161 countries, using data on fruit and vegetable availability in 1997 and 2010 and published estimates of the magnitude of the association between fruit and vegetable intake and gastric cancer, assuming a time lag of approximately 15 years. Countries classified as very high Human Development Index (HDI) presented median PF in 2012 much lower than low-HDI countries for both fruits (3·0 v. 10·2%, P<0·001) and vegetables (6·0 v. 11·9%, P<0·001). For vegetables only, PF significantly decreased until 2025 in most settings; however, this corresponded to a reduction in the absolute number of preventable gastric cancer cases in less than half of the countries. Increasing fruit and vegetable intake would allow preventing a relatively high proportion of gastric cancer cases, mostly in developing countries. Although declines in PF are predicted in the near future, changes in order to achieve healthier lifestyles may be insufficient to overcome the load of demographic variation to further reduce the gastric cancer burden.

Vegetation-climate feedbacks modulate rainfall patterns in Africa under future climate change

NASA Astrophysics Data System (ADS)

Wu, Minchao; Schurgers, Guy; Rummukainen, Markku; Smith, Benjamin; Samuelsson, Patrick; Jansson, Christer; Siltberg, Joe; May, Wilhelm

2016-07-01

Africa has been undergoing significant changes in climate and vegetation in recent decades, and continued changes may be expected over this century. Vegetation cover and composition impose important influences on the regional climate in Africa. Climate-driven changes in vegetation structure and the distribution of forests versus savannah and grassland may feed back to climate via shifts in the surface energy balance, hydrological cycle and resultant effects on surface pressure and larger-scale atmospheric circulation. We used a regional Earth system model incorporating interactive vegetation-atmosphere coupling to investigate the potential role of vegetation-mediated biophysical feedbacks on climate dynamics in Africa in an RCP8.5-based future climate scenario. The model was applied at high resolution (0.44 × 0.44°) for the CORDEX-Africa domain with boundary conditions from the CanESM2 general circulation model. We found that increased tree cover and leaf-area index (LAI) associated with a CO2 and climate-driven increase in net primary productivity, particularly over subtropical savannah areas, not only imposed important local effect on the regional climate by altering surface energy fluxes but also resulted in remote effects over central Africa by modulating the land-ocean temperature contrast, Atlantic Walker circulation and moisture inflow feeding the central African tropical rainforest region with precipitation. The vegetation-mediated feedbacks were in general negative with respect to temperature, dampening the warming trend simulated in the absence of feedbacks, and positive with respect to precipitation, enhancing rainfall reduction over the rainforest areas. Our results highlight the importance of accounting for vegetation-atmosphere interactions in climate projections for tropical and subtropical Africa.

Association between habitual dietary intake and lipoprotein subclass profile in healthy young adults.

PubMed

Bogl, L H; Pietiläinen, K H; Rissanen, A; Kangas, A J; Soininen, P; Rose, R J; Ala-Korpela, M; Kaprio, J

2013-11-01

Nutritional epidemiology is increasingly shifting its focus from studying single nutrients to the exploration of the whole diet utilizing dietary pattern analysis. We analyzed associations between habitual diet (including macronutrients, dietary patterns, biomarker of fish intake) and lipoprotein particle subclass profile in young adults. Complete dietary data (food-frequency questionnaire) and lipoprotein subclass profile (via nuclear magnetic resonance spectroscopy) were available for 663 subjects from the population-based FinnTwin12 study (57% women, age: 21-25 y). The serum docosahexaenoic to total fatty acid ratio was used as a biomarker of habitual fish consumption. Factor analysis identified 5 dietary patterns: "Fruit and vegetables", "Meat", "Sweets and desserts", "Junk food" and "Fish". After adjustment for sex, age, body mass index, waist circumference, physical activity, smoking status and alcohol intake, the "Junk food" pattern was positively related to serum triglycerides (r = 0.12, P = 0.002), a shift in the subclass distribution of VLDL toward larger particles (r = 0.12 for VLDL size, P < 0.001) and LDL toward smaller particles (r = -0.15 for LDL size, P < 0.001). In addition, higher scores on this pattern were positively correlated with concentrations of small, dense HDL (r = 0.16, P < 0.001). Habitual fish intake associated negatively with VLDL particle diameter ("Fish" pattern and biomarker) and positively with HDL particle diameter (biomarker). Our results suggest that in young adults, higher habitual fish consumption is related to favorable subclass distributions of VLDL and HDL, while junk food intake is associated with unfavorable alterations in the distribution of all lipoprotein subclasses independent of adiposity and other lifestyle factors. Copyright © 2012 Elsevier B.V. All rights reserved.

Modeling Above-Ground Biomass Across Multiple Circum-Arctic Tundra Sites Using High Spatial Resolution Remote Sensing

NASA Astrophysics Data System (ADS)

Räsänen, Aleksi; Juutinen, Sari; Aurela, Mika; Virtanen, Tarmo

2017-04-01

Biomass is one of the central bio-geophysical variables in Earth observation for tracking plant productivity, and flow of carbon, nutrients, and water. Most of the satellite based biomass mapping exercises in Arctic environments have been performed by using rather coarse spatial resolution data, e.g. Landsat and AVHRR which have spatial resolutions of 30 m and >1 km, respectively. While the coarse resolution images have high temporal resolution, they are incapable of capturing the fragmented nature of tundra environment and fine-scale changes in vegetation and carbon exchange patterns. Very high spatial resolution (VHSR, spatial resolution 0.5-2 m) satellite images have the potential to detect environmental variables with an ecologically sound spatial resolution. The usage of VHSR images has, nevertheless, been modest so far in biomass modeling in the Arctic. Our objectives were to use VHSR for predicting above ground biomass in tundra landscapes, evaluate whether a common predictive model can be applied across circum-Arctic tundra and peatland sites having different types of vegetation, and produce knowledge on distribution of plant functional types (PFT) in these sites. Such model development is dependent on ground-based surveys of vegetation with the same spatial resolution and extent with the VHSR images. In this study, we conducted ground-based surveys of vegetation composition and biomass in four different arctic tundra or peatland areas located in Russia, Canada, and Finland. First, we sorted species into PFTs and developed PFT-specific models to predict biomass on the basis of non-destructive measurements (cover, height). Second, we predicted overall biomass on landscape scale by combinations of single bands and vegetation indices of very high resolution satellite images (QuickBird or WorldView-2 images of the eight sites). We compared area-specific empirical regression models and common models that were applied across all sites. We found that NDVI was usually the highest scoring spectral indices in explaining biomass distribution with good explanatory power. Furthermore, models which had more than one explanatory variable had higher explanatory power than models with a single index. The dissimilarity between common and site-specific model estimates was, however, high and data indicates that variation in vegetation properties and its impact on spectral reflectance needs to be acknowledged. Our work produced knowledge on above-ground biomass distribution and contribution of PFTs across circum-Arctic low-growth landscapes and will contribute to developing space-borne vegetation monitoring schemes utilizing VHSR satellite images.

Review of crop growth and soil moisture monitoring from a ground-based instrument implementing the Interference Pattern GNSS-R Technique

NASA Astrophysics Data System (ADS)

Rodriguez-Alvarez, N.; Bosch-Lluis, X.; Camps, A.; Aguasca, A.; Vall-Llossera, M.; Valencia, E.; Ramos-Perez, I.; Park, H.

2011-12-01

Reflectometry using Global Navigation Satellite Systems signals (GNSSR) has been the focus of many studies during the past few years for a number of applications over different scenarios as land, ocean or snow and ice surfaces. In the past decade, its potential has increased yearly, with improved receivers and signal processors, from generic GNSS receivers whose signals were recorded in magnetic tapes to instruments that measure full Delay Doppler Maps (the power distribution of the reflected GNSS signal over the 2-D space of delay offsets and Doppler shifts) in real time. At present, these techniques are considered to be promising tools to retrieve geophysical parameters such as soil moisture, vegetation height, topography, altimetry, sea state and ice and snow thickness, among others. This paper focuses on the land geophysical retrievals (topography, vegetation height and soil moisture) performed from a ground-based instrument using the Interference Pattern Technique (IPT). This technique consists of the measurement of the power fluctuations of the interference signal resulting from the simultaneous reception of the direct and the reflected GNSS signals. The latest experiment performed using this technique over a maize field is shown in this paper. After a review of the previous results, this paper presents the latest experiment performed using this technique over a maize field. This new study provides a deeper analysis on the soil moisture retrieval by observing three irrigation-drying cycles and comparing them to different depths soil moisture probes. Furthermore, the height of the maize, almost 300 cm, has allowed testing the capabilities of the technique over dense and packed vegetation layers, with high vegetation water content.

Climate change and Arctic ecosystems: 1. Vegetation changes north of 55°N between the last glacial maximum, mid-Holocene, and present

USGS Publications Warehouse

Bigelow, N.H.; Brubaker, L.B.; Edwards, M.E.; Harrison, S.P.; Prentice, I.C.; Anderson, P.M.; Andreev, A.A.; Bartlein, P.J.; Christensen, T.R.; Cramer, W.; Kaplan, J.O.; Lozhkin, A.V.; Matveyeva, N.V.; Murray, D.F.; McGuire, A.D.; Razzhivin, V.Y.; Ritchie, J.C.; Smith, B.; Walker, D.A.; Gajewski, K.; Wolf, V.; Holmqvist, B.H.; Igarashi, Y.; Kremenetskii, K.; Paus, A.; Pisaric, M.F.J.; Volkova, V.S.

2003-01-01

A unified scheme to assign pollen samples to vegetation types was used to reconstruct vegetation patterns north of 55??N at the last glacial maximum (LGM) and mid-Holocene (6000 years B.P.). The pollen data set assembled for this purpose represents a comprehensive compilation based on the work of many projects and research groups. Five tundra types (cushion forb tundra, graminoid and forb tundra, prostrate dwarf-shrub tundra, erect dwarf-shrub tundra, and low- and high-shrub tundra) were distinguished and mapped on the basis of modern pollen surface samples. The tundra-forest boundary and the distributions of boreal and temperate forest types today were realistically reconstructed. During the mid-Holocene the tundra-forest boundary was north of its present position in some regions, but the pattern of this shift was strongly asymmetrical around the pole, with the largest northward shift in central Siberia (???200 km), little change in Beringia, and a southward shift in Keewatin and Labrador (???200 km). Low- and high-shrub tundra extended farther north than today. At the LGM, forests were absent from high latitudes. Graminoid and forb tundra abutted on temperate steppe in northwestern Eurasia while prostrate dwarf-shrub, erect dwarf-shrub, and graminoid and forb tundra formed a mosaic in Beringia. Graminoid and forb tundra is restricted today and does not form a large continuous biome, but the pollen data show that it was far more extensive at the LGM, while low- and high-shrub tundra were greatly reduced, illustrating the potential for climate change to dramatically alter the relative areas occupied by different vegetation types.

Long-term records of growth and distribution of conifers: Integration of paleoecology and physiological ecology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Graumlich, L.J.; Brubaker, L.B.

1995-07-01

The specter of human-induced alteration of atmospheric composition, and the associated changes in climate, have focused attention on how species, communities, and ecosystems respond to climate change. One source of information concerning this is the paleoecological record. Paleoecology offers insights in the nature of climate-vegetation interactions that derive from the well-documented response of plant communities to environmental changes of the past. The spatial and temporal resolution of paleoecological data sets has increased in recent decades, so that relatively detailed histories of conifer forests are available for much of North America and Europe. In addition, comparisons of records of past vegetationmore » dynamics to paleoclimatic simulations by general circulation models have improved the understanding of the role of climate in governing past vegetation change. Several major findings of paleoresearch have importance to investigations of the effects of future climate change on the Earth`s biota. These include the findings (1) that changing seasonality may result in unexpected vegetation patterns, (2) that climatic and vegetation changes can be rapid, with ecosystem-wide implications, and (3) that short-term, extreme events can have long-term effects on tree population structures. In this chapter, we discuss patterns of coniferous forest response to climatic variation at two temporal scales: the Late Quaternary and the last millennium. Our examples illustrate the wide range of potential responses of coniferous forests to climatic variation, and emphasize opportunities for applying paleoecological findings to questions of ecophysiological research. Although we rely largely on examples from North America, our conclusions are well-supported by parallel research results in Europe and Asia.« less

Integrated Remote Sensing and Wavelet Analyses for Screening Short-term Teleconnection Patterns in Northeast America

EPA Science Inventory

Global sea surface temperature (SST) anomalies have a demonstrable effect on vegetation dynamics and precipitation patterns throughout the continental U.S. SST variations have been correlated with greenness (vegetation densities) and precipitation via ocean-atmospheric interactio...

Assessment of groundwater input and water quality changes impacting natural vegetation in the Loxahatchee River and floodplain ecosystem, Florida

USGS Publications Warehouse

Orem, William H.; Swarzenski, Peter W.; McPherson, Benjamin F.; Hedgepath, Marion; Lerch, Harry E.; Reich, Christopher; Torres, Arturo E.; Corum, Margo D.; Roberts, Richard E.

2007-01-01

The Loxahatchee River and Estuary are small, shallow, water bodies located in southeastern Florida. Historically, the Northwest Branch (Fork) of the Loxahatchee River was primarily a freshwater system. In 1947, the river inlet at Jupiter was dredged for navigation and has remained permanently open since that time. Drainage patterns within the basin have also been altered significantly due to land development, road construction (e.g., Florida Turnpike), and construction of the C-18 and other canals. These anthropogenic activities along with sea level rise have resulted in significant adverse impacts on the ecosystem over the last several decades, including increased saltwater encroachment and undesired vegetation changes in the floodplain. The problem of saltwater intrusion and vegetation degradation in the Loxahatchee River may be partly induced by diminished freshwater input, from both surface water and ground water into the River system. The overall objective of this project was to assess the seasonal surface water and groundwater interaction and the influence of the biogeochemical characteristics of shallow groundwater and porewater on vegetation health in the Loxahatchee floodplain. The hypothesis tested are: (1) groundwater influx constitutes a significant component of the overall flow of water into the Loxahatchee River; (2) salinity and other chemical constituents in shallow groundwater and porewater of the river floodplain may affect the distribution and health of the floodplain vegetation.

Analysis of shifts in the spatial distribution of vegetation due to climate change

NASA Astrophysics Data System (ADS)

del Jesus, Manuel; Díez-Sierra, Javier; Rinaldo, Andrea; Rodríguez-Iturbe, Ignacio

2017-04-01

Climate change will modify the statistical regime of most climatological variables, inducing changes on average values and in the natural variability of environmental variables. These environmental variables may be used to explain the spatial distribution of functional types of vegetation in arid and semiarid watersheds through the use of plant optimization theories. Therefore, plant optimization theories may be used to approximate the response of the spatial distribution of vegetation to a changing climate. Predicting changes in these spatial distributions is important to understand how climate change may affect vegetated ecosystems, but it is also important for hydrological engineering applications where climate change effects on water availability are assessed. In this work, Maximum Entropy Production (MEP) is used as the plant optimization theory that describes the spatial distribution of functional types of vegetation. Current climatological conditions are obtained from direct observations from meteorological stations. Climate change effects are evaluated for different temporal horizons and different climate change scenarios using numerical model outputs from the CMIP5. Rainfall estimates are downscaled by means of a stochastic point process used to model rainfall. The study is carried out for the Rio Salado watershed, located within the Sevilleta LTER site, in New Mexico (USA). Results show the expected changes in the spatial distribution of vegetation and allow to evaluate the expected variability of the changes. The updated spatial distributions allow to evaluate the vegetated ecosystem health and its updated resilience. These results can then be used to inform the hydrological modeling part of climate change assessments analyzing water availability in arid and semiarid watersheds.

Geomorphometric correlations of vegetation cover properties and topographic karst features based on high-resolution LiDAR DTM of Aggtelek Karst, NE Hungary

NASA Astrophysics Data System (ADS)

Székely, Balázs; Telbisz, Tamás; Koma, Zsófia; Kelemen, Kristóf; Szmorad, Ferenc; Deák, Márton; Látos, Tamás; Standovár, Tibor

2015-04-01

Topography and lithology are two major factors influencing the vegetation cover, its mosaic pattern and lateral transitions. In karstic areas the topography has a high diversity, microtopographic landforms influence the local ecological setting, vegetation structure. Presence of sinkholes of various sizes and geometric arrangements causes rapid lateral variation of the slope, aspect patterns as well as highly modify the soil water balance in time and space. These diversity of factors defines a mosaicked habitat pattern for vegetation assemblages. The World Heritage Site Aggtelek Karst/Slovakian Karst Caves has characteristic natural and environmental properties concerning the geomorphological as well as the ecological values. In order to be able to study the topographic influence on the ecological setting, a high-resolution digital terrain model (DTM) and digital surface model (DSM) have been derived from airborne laser scanning data depicting the karstic micro- and macrotopographic Landscape elements and the envelope surface of the canopy. Additional vegetation parameters like closure and average height have been derived from a normalized digital surface model (nDSM). Extensive mapping of vegetation properties has been carried out: centered on points of a grid array several vegetation-specific data - including composition and structure of tree and shrub layers, herbacesous vegetation and tree regeneration - have been acquired. Various classification patterns - based on trees pecies composition, vertical vegetation structure - have been derived from this data set. The comparison of the vegetation classification data and the geomorphometric DTM derivatives yielded interesting results. Certain vegetation characteristics often correlate with the geomorphometric properties. We interpret this similarity as sensitivity of vegetion to fine-scale variations in geomorphic properties like aspect, illumination conditions and soil properties. However, in many cases the vegetation pattern shows no correlation with natural settings. It may be the result of human impact, which actively formed the local land use in these hilly-low mountain karst area since the Middle Ages. These studies have been financed partly by the following projects: data acquisition: "Hungarian-Slovakian Transnational Cooperation Programme 2007-2013", "Management of World Heritage Aggtelek Karst/Slovakian Karst Caves" (HUSK/1101/221/0180, Aggtelek NP), data evaluation: 'Multipurpose assessment serving forest biodiversity conservation in the Carpathian region of Hungary', Swiss-Hungarian Cooperation Programme (SH/4/13 Project), and Hungarian National Research Fund OTKA NK83400 and OTKA 104811. BS contributed as an Alexander von Humboldt Research Fellow, TT was supported by the János Bolyai Scolarship of the Hungarian Academy of Sciences.

Holocene vegetation and climate dynamics of NE China based on the pollen record from Sihailongwan Maar Lake

NASA Astrophysics Data System (ADS)

Stebich, Martina; Rehfeld, Kira; Schlütz, Frank; Tarasov, Pavel E.; Liu, Jiaqi; Mingram, Jens

2015-09-01

High-resolution palynological analysis on annually laminated sediments of Sihailongwan Maar Lake (SHL) provides new insights into the Holocene vegetation and climate dynamics of NE China. The robust chronology of the presented record is based on varve counting and AMS radiocarbon dates from terrestrial plant macro-remains. In addition to the qualitative interpretation of the pollen data, we provide quantitative reconstructions of vegetation and climate based on the method of biomization and weighted averaging partial least squares regression (WA-PLS) technique, respectively. Power spectra were computed to investigate the frequency domain distribution of proxy signals and potential natural periodicities. Pollen assemblages, pollen-derived biome scores and climate variables as well as the cyclicity pattern indicate that NE China experienced significant changes in temperature and moisture conditions during the Holocene. Within the earliest phase of the Holocene, a large-scale reorganization of vegetation occurred, reflecting the reconstructed shift towards higher temperatures and precipitation values and the initial Holocene strengthening and northward expansion of the East Asian summer monsoon (EASM). Afterwards, summer temperatures remain at a high level, whereas the reconstructed precipitation shows an increasing trend until approximately 4000 cal. yr BP. Since 3500 cal. yr BP, temperature and precipitation values decline, indicating moderate cooling and weakening of the EASM. A distinct periodicity of 550-600 years and evidence of a Mid-Holocene transition from a temperature-triggered to a predominantly moisture-triggered climate regime are derived from the power spectra analysis. The results obtained from SHL are largely consistent with other palaeoenvironmental records from NE China, substantiating the regional nature of the reconstructed vegetation and climate patterns. However, the reconstructed climate changes contrast with the moisture evolution recorded in S China and the mid-latitude (semi-)arid regions of N China. Whereas a clear insolation-related trend of monsoon intensity over the Holocene is lacking from the SHL record, variations in the coupled atmosphere-Pacific Ocean system can largely explain the reconstructed changes in NE China.

Animal and vegetation patterns in natural and man-made bog pools: implications for restoration

USGS Publications Warehouse

Mazerolle, M.J.; Poulin, M.; Lavoie, C.; Rochefort, L.; Desrochers, A.; Drolet, B.

2006-01-01

1. Peatlands have suffered great losses following drainage for agriculture, forestry, urbanisation, or peat mining, near inhabited areas. We evaluated the faunal and vegetation patterns after restoration of a peatland formerly mined for peat. We assessed whether bog pools created during restoration are similar to natural bog pools in terms of water chemistry, vegetation structure and composition, as well as amphibian and arthropod occurrence patterns. 2. Both avian species richness and peatland vegetation cover at the site increased following restoration. Within bog pools, however, the vegetation composition differed between natural and man-made pools. The cover of low shrubs, Sphagnum moss, submerged, emergent and floating vegetation in man-made pools was lower than in natural pools, whereas pH was higher than in typical bog pools. Dominant plant species also differed between man-made and natural pools. 3. Amphibian tadpoles, juveniles and adults occurred more often in man-made pools than natural bog pools. Although some arthropods, including Coleoptera bog specialists, readily colonised the pools, their abundance was two to 26 times lower than in natural bog pools. Plant introduction in bog pools, at the stocking densities we applied, had no effect on the occurrence of most groups. 4. We conclude that our restoration efforts were partially successful. Peatland-wide vegetation patterns following restoration mimicked those of natural peatlands, but 4 years were not sufficient for man-made pools to fully emulate the characteristics of natural bog pools.

Snow depth spatial structure from hillslope to basin scale

NASA Astrophysics Data System (ADS)

Deems, J. S.

2017-12-01

Knowledge of spatial patterns of snow accumulation is required for understanding the hydrology, climatology, and ecology of mountain regions. Spatial structure in snow accumulation patterns changes with the scale of observation, a feature that has been characterized using fractal dimensions calculated from lidar-derived snow depth maps: fractal scaling structure at short length scales, with a `scale break' transition to more stochastic patterns at longer separation distances. Previous work has shown that this fractal structure of snow depth distributions differs between sites with different vegetation and terrain characteristics. Forested areas showed a transition to a nearly random spatial distribution at a much shorter lag distance than do unforested sites, enabling a statistical characterization. Alpine areas, however, showed strong spatial structure for a much wider scale range, and were the source of the dominant spatial pattern observable over a wider area. These spatial structure characteristics suggest that the choice of measurement or model resolution (satellite sensor, DEM, field survey point spacing, etc.) will strongly affect the estimates of snow volume or mass, as well as the magnitude of spatial variability. These prior efforts used data sets that were high resolution ( 1 m laser point spacing) but of limited extent ( 1 km2), constraining detection of scale features such as fractal dimension or scale breaks to areas of relatively similar characteristics and to lag distances of under 500 m. New datasets available from the NASA JPL Airborne Snow Observatory (ASO) provide similar resolution but over large areas, enabling assessment of snow spatial structure across an entire watershed, or in similar vegetation or physiography but in different parts of the basin. Additionally, the multi-year ASO time series allows an investigation into the temporal stability of these scale characteristics, within a single snow season and between seasons of strongly varying accumulation totals and patterns. This presentation will explore initial results from this study, using data from the Tuolumne River Basin in California, USA. Fractal scaling characteristics derived from ASO lidar snow depth measurements are examined at the basin scale, as well as in varying topographic and forest cover environments.

Spatial patterns in vegetation fires in the Indian region.

PubMed

Vadrevu, Krishna Prasad; Badarinath, K V S; Anuradha, Eaturu

2008-12-01

In this study, we used fire count datasets derived from Along Track Scanning Radiometer (ATSR) satellite to characterize spatial patterns in fire occurrences across highly diverse geographical, vegetation and topographic gradients in the Indian region. For characterizing the spatial patterns of fire occurrences, observed fire point patterns were tested against the hypothesis of a complete spatial random (CSR) pattern using three different techniques, the quadrat analysis, nearest neighbor analysis and Ripley's K function. Hierarchical nearest neighboring technique was used to depict the 'hotspots' of fire incidents. Of the different states, highest fire counts were recorded in Madhya Pradesh (14.77%) followed by Gujarat (10.86%), Maharastra (9.92%), Mizoram (7.66%), Jharkhand (6.41%), etc. With respect to the vegetation categories, highest number of fires were recorded in agricultural regions (40.26%) followed by tropical moist deciduous vegetation (12.72), dry deciduous vegetation (11.40%), abandoned slash and burn secondary forests (9.04%), tropical montane forests (8.07%) followed by others. Analysis of fire counts based on elevation and slope range suggested that maximum number of fires occurred in low and medium elevation types and in very low to low-slope categories. Results from three different spatial techniques for spatial pattern suggested clustered pattern in fire events compared to CSR. Most importantly, results from Ripley's K statistic suggested that fire events are highly clustered at a lag-distance of 125 miles. Hierarchical nearest neighboring clustering technique identified significant clusters of fire 'hotspots' in different states in northeast and central India. The implications of these results in fire management and mitigation were discussed. Also, this study highlights the potential of spatial point pattern statistics in environmental monitoring and assessment studies with special reference to fire events in the Indian region.

Vegetable-based dietary pattern and liver cancer risk: results from the Shanghai women's and men's health studies.

PubMed

Zhang, Wei; Xiang, Yong-Bing; Li, Hong-Lan; Yang, Gong; Cai, Hui; Ji, Bu-Tian; Gao, Yu-Tang; Zheng, Wei; Shu, Xiao-Ou

2013-10-01

Although dietary patterns, specific foods, and their constituents have been linked to cancer risk, the role of dietary patterns and specific food groups in liver cancer risk has not been investigated. In the Shanghai Women's Health Study (SWHS) and Shanghai Men's Health Study (SMHS), two cohort studies of 132 837 Chinese women and men, we evaluated the relationship between dietary patterns, food groups, and liver cancer risk. Through in-person interviews, dietary information intake over the preceding year was collected by using a validated food-frequency questionnaire. Cox regression model was used to estimate hazard ratios and 95% confidence intervals with adjustment for potential confounders. During an average follow-up of 10.9 (SWHS) or 5.5 (SMHS) years, 267 incident liver cancer cases were identified after the first 2 years of study enrolment. Three dietary patterns were derived by factor analysis. A vegetable-based dietary pattern was inversely associated with liver cancer; hazard ratios (95% confidence intervals) for the lowest to highest quartiles were: 1.00; 0.98 (0.71-1.35); 0.93 (0.67-1.29); and 0.58 (0.40-0.84); P(trend) = 0.01. The association was stronger among participants with a history of chronic liver disease. Further analyses showed high intakes of celery, mushrooms, allium vegetables, composite vegetables (including asparagus lettuce and garland chrysanthemum), legumes and legume products were associated with reduced liver cancer risk (all P(trend) < 0.05). Fruit- and meat-based dietary patterns were not associated with liver cancer risk. Our study suggests that a vegetable-based dietary pattern is associated with reduced liver cancer risk. © 2013 Japanese Cancer Association.

The response of vegetation distribution, ecosystem productivity, and fire in California to future climate scenarios simulated by the MC1 dynamic vegetation dynamic.

Treesearch

James M. Lenihan; Dominique Bachelet; Raymond Drapek; Ronald P. Neilson

2006-01-01

The objective of this study was to dynamically simulate the response of vegetation distribution, carbon, and fire to three scenarios of future climate change for California using the MAPSS-CENTURY (MCI) dynamic general vegetation model. Under all three scenarios, Alpine/Subalpine Forest cover declined with increased growing season length and warmth, and increases in...

Subsurface flow and vegetation patterns in tidal environments

NASA Astrophysics Data System (ADS)

Ursino, Nadia; Silvestri, Sonia; Marani, Marco

2004-05-01

Tidal environments are characterized by a complex interplay of hydrological, geomorphic, and biological processes, and their understanding and modeling thus require the explicit description of both their biotic and abiotic components. In particular, the presence and spatial distribution of salt marsh vegetation (a key factor in the stabilization of the surface soil) have been suggested to be related to topographic factors and to soil moisture patterns, but a general, process-based comprehension of this relationship has not yet been achieved. The present paper describes a finite element model of saturated-unsaturated subsurface flow in a schematic salt marsh, driven by tidal fluctuations and evapotranspiration. The conditions leading to the establishment of preferentially aerated subsurface zones are studied, and inferences regarding the development and spatial distribution of salt marsh vegetation are drawn, with important implications for the overall ecogeomorphological dynamics of tidal environments. Our results show that subsurface water flow in the marsh induces complex water table dynamics, even when the tidal forcing has a simple sinusoidal form. The definition of a space-dependent aeration time is then proposed to characterize root aeration. The model shows that salt marsh subsurface flow depends on the distance from the nearest creek or channel and that the subsurface water movement near tidal creeks is both vertical and horizontal, while farther from creeks, it is primarily vertical. Moreover, the study shows that if the soil saturated conductivity is relatively low (10-6 m s-1, values quite common in salt marsh areas), a persistently unsaturated zone is present below the soil surface even after the tide has flooded the marsh; this provides evidence of the presence of an aerated layer allowing a prolonged presence of oxygen for aerobic root respiration. The results further show that plant transpiration increases the extent and persistence of the aerated layer, thereby introducing a strong positive feedback: Pioneer plants on marsh edges have the effect of increasing soil oxygen availability, thus creating the conditions for the further development of other plant communities.

Spatial distribution by Canistropsis microps (E. Morren ex Mez) Leme (Bromeliaceae: Bromelioideae) in the Atlantic rain forest in Ilha Grande, Southeastern Brazil.

PubMed

Nunes-Freitas, A F; Rocha, C F D

2007-08-01

Canistropsis microps (Bromeliaceae: Bromelioideae) is an endemic species of Atlantic rain forest areas in Rio de Janeiro State, which are very abundant in not very disturbed forests in Ilha Grande, on the southern coast of the State. In this study, we analyzed the vertical and horizontal distribution patterns of the species in an area of rain forest with little evidence of disturbance at Vila Dois Rios, Ilha Grande, relating the patterns to sunlight in the microhabitat. We also identified the types of substrate used by the species and the rate of asexual reproduction. Canistropsis microps had high densities (estimated at 84,425 rosettes/ha), and has an aggregated distribution (Id = 2.86). About 80% of the rosettes were generated by clonal growth, whereas less than 20% were produced from seedlings. Most of the rosettes were found on straight tree trunks (DBH > 50 cm). There was a significant inverse correlation between the incidence of sunlight in the habitat and the abundance of individuals. Rosettes were found up to a maximum height of 9.5 m, but most occured between 1.5 and 5.5 m, where light varied from 25 to 50 micromol x s(-1) x m(-2). We conclude that vertical and horizontal distribution patterns in C. microps may be partially explained by the occurrence of appropriate substrate, an intensity of sunlight favorable to the development of the species and to a high rate of vegetative reproduction.

Drainage and fertilization effects on nutrient availability in an ombrotrophic peatland.

PubMed

Wang, Meng; Talbot, Julie; Moore, Tim R

2018-04-15

Nutrient availability is an important control on the vegetation distribution, productivity and functioning of peatland ecosystems and we examined spatial and temporal patterns of nutrient availability through ion exchange at Mer Bleue bog, southeast Ontario, Canada. We installed ion exchange probes at 5-15cm for 4weeks and determined nutrient sorption at undisturbed sites as well as those affected by nitrogen (N), phosphorus (P), potassium (K) fertilization and drainage. Under undisturbed conditions, the bog had very small amount of available nutrients, especially N (ammonium>nitrate) and P, and exhibited small variations in nutrient availability during the growing season (May to October). The increase in NPK availability upon fertilization was short-lived over the season and the stoichiometry of available NPK captured by the probes was mismatched with the vegetation. The increase in nutrient availability with drainage was confounded by substantial changes in vegetation. We compare these results with data from other Canadian bogs and fens to provide baseline data on nutrient availability in peatlands. Copyright © 2017 Elsevier B.V. All rights reserved.

Variations in the Life Cycle of Anemone patens L. (Ranunculaceae) in Wild Populations of Canada

PubMed Central

Kricsfalusy, Vladimir

2016-01-01

Based on a study of a perennial herb Anemone patens L. (Ranunculaceae) in a variety of natural habitats in Saskatchewan, Canada, eight life stages (seed, seedling, juvenile, immature, vegetative, generative, subsenile, and senile) are distinguished and characterized in detail. The species ontogenetic growth patterns are investigated. A. patens has a long life cycle that may last for several decades which leads to the formation of compact clumps. The distribution and age of clumps vary substantially in different environments with different levels of disturbance. The plant ontogeny includes the regular cycle with reproduction occurring through seeds. There is an optional subsenile vegetative disintegration at the end of the life span. The following variations in the life cycle of A. patens are identified: with slower development in young age, with an accelerated development, with omission of the generative stage, with retrogression to previous life stages in mature age, and with vegetative dormancy. The range of variations in the life cycle of A. patens may play an important role in maintaining population stability in different environmental conditions and management regimes. PMID:27376340

On the role of vegetation in the formation of river anabranching patterns

NASA Astrophysics Data System (ADS)

Crouzy, B.; D'Odorico, P.; Wütrich, D.; Perona, P.

2012-04-01

Part of studies on the couplings between the evolution of riparian vegetation and the river morphodynamics, we investigate the effect of spatial interactions between vegetation located at different positions within the channel. This work generalizes the experimental and theoretical results by Perona et al. and by Crouzy and Perona (both Advances in Water Resources, in Press) on colonization of riverbars by seedlings or large woody debris by relaxing the hypothesis made in those two works of the biomass growth and uprooting being independent on the presence of neighboring plants. While the hypothesis of independent vegetation growth and uprooting is justified for sparse vegetation cover or young seedlings, it fails as soon as the canopy significantly disturbs the flow or changes the sediment stability. Then, flow-mediated interactions between riparian vegetation located at different positions within the channel can be observed. Those interactions are either constructive or destructive. For example, a region favorable to the development of biomass appears on the lee side of a vegetated obstacle (with bleed flow) due to increased deposition of seeds and sediment (Schnauder and Moggridge, 2008) while conversely scouring can be increased laterally due to obstacle-induced flow diversion (Roulund et al., 2005; Melville and Sutherland, 1988; Zong and Nepf, 2008). We focus on the role of vegetation in the formation of the regular vegetated ridge patterns found in ephemeral rivers (see for example the work by Tooth and Nanson, 2004 on anabranching patterns) or as a succession of swales and ridges on the inside of meander bends (scroll bars). From the analysis of aerial images, we obtain the characteristic length scale of the patterns. We show how in the limit where the hydrological (interarrival time of floods) and the biological (germination and growth rates) timescales are comparable the combination between both positive and negative feedbacks between vegetation located at different positions can lead to the spatial organization of the vegetation. Classically, the presence of the anabranches has been ascribed to an optimization of the sediment load transport (Huang and Nanson, 2007) or for the scroll bars to channel migration, without explicitly accounting for the role of vegetation.

Dietary Patterns and Body Mass Index in Children with Autism and Typically Developing Children

PubMed Central

Evans, E. Whitney; Must, Aviva; Anderson, Sarah E.; Curtin, Carol; Scampini, Renee; Maslin, Melissa; Bandini, Linda

2012-01-01

To determine whether dietary patterns (juice and sweetened non-dairy beverages, fruits, vegetables, fruits & vegetables, snack foods, and kid’s meals) and associations between dietary patterns and body mass index (BMI) differed between 53 children with autism spectrum disorders (ASD) and 58 typically developing children, ages 3 to 11, multivariate regression models including interaction terms were used. Children with ASD were found to consume significantly more daily servings of sweetened beverages (2.6 versus 1.7, p=0.03) and snack foods (4.0 versus 3.0, p=0.01) and significantly fewer daily servings of fruits and vegetables (3.1 versus 4.4, p=0.006) than typically developing children. There was no evidence of statistical interaction between any of the dietary patterns and BMI z-score with autism status. Among all children, fruits and vegetables (p=0.004) and fruits alone (p=0.005) were positively associated with BMI z-score in our multivariate models. Children with ASD consume more energy-dense foods than typically developing children; however, in our sample, only fruits and vegetables were positively associated with BMI z-score. PMID:22936951

[Transfer characteristics of cadmium in soil-vegetable-insect food chain].

PubMed

Ding, Ping; Zhuang, Ping; Li, Zhi-An; Xia, Han-Ping; Tai, Yi-Ping; Lu, Huan-Ping

2012-11-01

Taking two kinds of vegetables (Brassica rapa and Amaranthus mangostanus) and one insect species (Prodenia litura) as test materials, a greenhouse pot experiment was conducted to study the transfer characteristics of cadmium (Cd) in soil-vegetable-insect food chain and the distribution patters of different Cd chemical forms in the organs of the two vegetables. With the increasing concentration of applied Cd in soil, the biomass of the two vegetables decreased significantly, while the Cd concentration in the vegetables had a significant increase. The Cd concentration in the vegetable organs decreased in the order of stem > root > leaf for A. mangostanus, and of stem > leaf > root for B. rapa. The Cd concentration in P. litura larvae also increased with the increasing concentration of Cd in soil, and the maximum Cd concentration in the P. litura larvae on B. rapa and A. mangostanus was 36.7 and 46.3 mg x kg(-1), respectively. In the feces of the larvae on B. rapa and A. mangostanus, the Cd concentration was up to 190 and 229.8 mg x kg(-1), respectively, suggesting that the most part of Cd absorbed by P. litura larvae was excreted out of their bodies via feces. In the organs of the two vegetables, NaCl-extractable Cd was the dominant Cd form (> 70%), followed by d-H2O- and ethanol-extractable Cd, while the HAc-extractable Cd (insoluble cadmium phosphate), HCl-extractable Cd (insoluble cadmium oxalate), and residual Cd only had a very low concentration. Such a present pattern of different Cd forms in vegetable organs could be conducive to the Cd transfer in the food chain. P. litura could ease Cd poison by excreting large amount of absorbed Cd via feces, and effectively restrict the transfer of Cd to next trophic level. Since B. rapa and A. mangostanus could accumulate large amount of Cd in their biomass, the two vegetables were suggested not to be planted in highly Cd-contaminated soil.

Dietary Patterns during Complementary Feeding and Later Outcomes.

PubMed

Emmett, Pauline M

2016-01-01

Guidelines for healthy infant feeding provide advice on breastfeeding and complementary feeding. The Avon Longitudinal Study of Parents and Children (ALSPAC) derived dietary patterns in comparison to infant feeding guidelines and by using principal components analysis (PCA). The ALSPAC cohort was recruited during pregnancy. Parent-completed questionnaires assessed diet at age 6 and 15 months. Children were weighed and measured at 7 years of age and IQ was assessed at 8 years. A complementary feeding utility index was calculated in relation to 14 feeding recommendations. High scores on the index were due to longer breastfeeding, and feeding more fruit and vegetables and less ready-prepared baby foods. The index scores were positively related to IQ and 'healthy' dietary patterns in childhood. In infancy four dietary patterns were derived from PCA at each age. Three occurred at both ages: 'HM traditional' (home-made meat, vegetables and desserts), 'discretionary' (processed adult foods) and 'RM baby foods' (commercial ready-made baby foods). A 'breastfeeding' pattern was derived at 6 months, with fruit and vegetables included. At 15 months, a 'HM contemporary' pattern included cheese, fish, nuts, legumes, fruit and vegetables. The 'discretionary' and 'RM baby foods' patterns at both ages were negatively associated, while the 'breastfeeding' and 'HM contemporary' patterns were positively associated with IQ. These results suggest that infant diet influences cognitive development in children and may set a trend for later eating patterns. © 2016 Nestec Ltd., Vevey/S. Karger AG, Basel.

Twenty-year trends in dietary patterns in French-speaking Switzerland: toward healthier eating.

PubMed

Marques-Vidal, Pedro; Gaspoz, Jean-Michel; Theler, Jean-Marc; Guessous, Idris

2017-07-01

Background: Dietary patterns provide a summary of dietary intake, but to our knowledge, few studies have assessed trends in dietary patterns in the population. Objective: The aim was to assess 20-y trends in dietary patterns in a representative sample of the Geneva, Switzerland, population with the consideration of age, sex, education, and generation. Design: Repeated, independent cross-sectional studies were conducted between 1993 and 2014. Dietary intake was assessed by using a validated food-frequency questionnaire. Dietary patterns were assessed by using principal components analyses. Results: Among 18,763 adults, 1 healthy ("fish and vegetables") and 2 unhealthy ("meat and chips" and "chocolate and sweets") patterns were identified. Scores for the "fish and vegetables" pattern increased, whereas the "meat and chips" and "chocolate and sweets" pattern scores decreased in both sexes and across all age groups. The stronger increase in the "fish and vegetables" pattern score among the less well-educated participants led to a narrowing of educational differences (mean ± SD scores in 1993: -0.56 ± 1.39 compared with -0.05 ± 1.58 in low- compared with highly educated groups, respectively; P < 0.001; scores in 2014: 0.28 ± 1.64 compared with 0.24 ± 1.83, respectively; P = 0.772). Generational analysis showed that older age groups tended to show smaller changes than younger age groups: the yearly score change in "chocolate and sweets" was -0.021 (95% CI: -0.027, -0.014; P < 0.001) for the 35- to 44-y cohort compared with -0.002 (95% CI: -0.009, 0.005; P = 0.546) for the 45- to 54-y cohort. Conclusions: Three dietary patterns were identified; scores for the "fish and vegetables" pattern increased, whereas the "meat and chips" and the "chocolate and sweets" pattern scores decreased. The stronger increases in the "fish and vegetables" pattern score among the less well-educated participants led to a smaller difference in dietary intake across the different educational levels. © 2017 American Society for Nutrition.

Comprehensive Understanding for Vegetated Scene Radiance Relationships

NASA Technical Reports Server (NTRS)

Kimes, D. S.; Deering, D. W.

1984-01-01

The improvement of our fundamental understanding of the dynamics of directional scattering properties of vegetation canopies through analysis of field data and model simulation data is discussed. Directional reflectance distributions spanning the entire existance hemisphere were measured in two field studies; one using a Mark III 3-band radiometer and one using rapid scanning bidirectional field instrument called PARABOLA. Surfaces measured included corn, soybeans, bare soils, grass lawn, orchard grass, alfalfa, cotton row crops, plowed field, annual grassland, stipa grass, hard wheat, salt plain shrubland, and irrigated wheat. Some structural and optical measurements were taken. Field data show unique reflectance distributions ranging from bare soil to complete vegetation canopies. Physical mechanisms causing these trends are proposed based on scattering properties of soil and vegetation. Soil exhibited a strong backscattering peak toward the Sun. Complete vegetation exhibited a bowl distribution with the minimum reflectance near nadir. Incomplete vegetation canopies show shifting of the minimum reflectance off of nadir in the forward scattering direction because both the scattering properties or the vegetation and soil are observed.

Alluvial deposits and plant distribution in an Amazonian lowland megafan

NASA Astrophysics Data System (ADS)

Zani, H.; Rossetti, D.; Cremon; Cohen, M.; Pessenda, L. C.

2012-12-01

A large volume of sandy alluvial deposits (> 1000 km2) characterizes a flat wetland in northern Amazonia. These have been recently described as the sedimentary record of a megafan system, which have a distinct triangular shape produced by highly migratory distributary rivers. The vegetation map suggests that this megafan is dominated by open vegetation in sharp contact with the surround rainforest. Understanding the relationship between geomorphological processes and vegetation distribution is crucial to decipher and conserve the biodiversity in this Amazonian ecosystem. In this study we interpret plant dynamics over time, and investigate its potential control by sedimentary processes during landscape evolution. The study area is located in the Viruá National Park. Two field campaigns were undertaken in the dry seasons of 2010 and 2011 and the sampling sites were selected by combining accessibility and representativeness. Vegetation contrasts were recorded along a transect in the medial section of the Viruá megafan. Due to the absence of outcrops, samples were extracted using a core device, which allowed sampling up to a depth of 7.5 m. All cores were opened and described in the field, with 5 cm3 samples collected at 20 cm intervals. The δ13C of organic matter was used as a proxy to distinguish between C3 and C4 plant communities. The chronology was established based on radiocarbon dating. The results suggest that the cores from forested areas show the most depleted values of δ13C, ranging from -32.16 to -27.28‰. The δ13C curve in these areas displays typical C3 land plant values for the entire record, which covers most of the Holocene. This finding indicates that either the vegetation remained stable over time or the sites were dominated by aquatic environments with freshwater plants before forest establishment. The cores from the open vegetation areas show a progressive upward enrichment in δ13C values, which range from -28.50 to -19.59‰. This trend is more pronounced after de mid-Holocene, suggesting that the open vegetation, represented mostly by C4 land plants, evolved only more recently. Based on our isotope data, a model is proposed taking into account the influence of sedimentary dynamics on the modern pattern of plan distribution. The establishment of open vegetation occurred at different times depending on location over the megafan area, varying from around 3,000 to 6,400 cal yrs BP. As sedimentation took place, areas located far from the surrounding rainforest were prone to inputs of organic matter derived from open vegetation, whereas the contribution of organic matter derived from arboreous vegetation increases toward the areas located closer to the rainforest. In general, open vegetation is constrained to depositional sites that remained active until relatively recent Holocene times, while surrounding areas with a relatively older geological history are covered by dense forest. The results presented here consist in a striking example of the influence of sedimentary processes during the Late Pleistocene-Holocene on the development of modern plants of this Amazonian lowland.

Dynamically incorporating late-successional forest in sustainable landscapes

Treesearch

Ann E. Camp; Paul F. Hessburg; Richard L. Everett

1996-01-01

Ecosystems and landscapes change over time as a function of vegetation characteristics and disturbance regimes, including fire. Interactions between disturbance events and forest development (succession) create patterns of vegetation across landscapes. These patterns result from, and change with respect to, species compositions and structures that arise from...

A STATISTICAL THERMODYNAMIC MODEL OF THE ORGANIZATIONAL ORDER OF VEGETATION. (R827676)

EPA Science Inventory

The complex pattern of vegetation is the macroscopic manifestation of biological diversity and the ecological order in space and time. How is this overwhelmingly diverse, yet wonderfully ordered spatial pattern formed, and how does it evolve? To answer these questions, most tr...

Seasonal Biophysical Dynamics of the Amazon from Space Using MODIS Vegetation Indices

NASA Astrophysics Data System (ADS)

Huete, A. R.; Didan, K.; Ratana, P.; Ferreira, L.

2002-12-01

We utilized the Terra- Moderate Resolution Imaging Spectroradiometer (MODIS) Vegetation Index (VI) products to analyze the seasonal and spatial patterns of photosynthetic vegetation activity over the Amazon Basin and surrounding regions of Brazil. The seasonal patterns of vegetation activity were studied along two, eco-climatic transects extending from (1) the cerrado region (Brasilia National Park) to the seasonal tropical forest (Tapajos National Forest) and (2) the caatinga biome to the seasonal and per-humid tropical forests. In addition to the climatic transects, we also investigated the seasonal dynamics of altered, land conversion areas associated with pastures and clearcutting land use activities. Both the normalized difference vegetation index (NDVI) and the enhanced vegetation index (EVI) at 250-m, 500-m, and 1-km were used to extract seasonal profile curves. The quality assurance (QA) information of the output products was used in noise removal and data filtering prior to the generation of the seasonal profiles. Histogram analyses were also performed at coarse (biome) scale and fine, site intensive (flux towers) scale. The seasonal patterns of the cerrado and caatinga were very pronounced with distinct dry and wet seasonal trends. We observed decreasing dry-wet seasonal patterns in the transitional areas near Araguaia National Park. In contrast, the seasonal behavior of the tropical forests were much harder to assess, but indicated slight seasonal trends that ran counter to rainfall activity. This may be attributed to new leaf growth in the dry season. We further found MODIS VI seasonal patterns to vary significantly in land converted and land degraded areas.

[Evaluation on environmental quality of heavy metals in soils and vegetables based on geostatistics and GIS].

PubMed

Xie, Zheng-miao; Li, Jing; Wang, Bi-ling; Chen, Jian-jun

2006-10-01

Contents of heavy metals (Pb, Zn, Cd, Cu) in soils and vegetables from Dongguan town in Shangyu city, China were studied using geostatistical analysis and GIS technique to evaluate environmental quality. Based on the evaluation criteria, the distribution of the spatial variability of heavy metals in soil-vegetable system was mapped and analyzed. The results showed that the distribution of soil heavy metals in a large number of soil samples in Dongguan town was asymmetric. The contents of Zn and Cu were lower than those of Cd and Pb. The concentrations distribution of Pb, Zn, Cd and Cu in soils and vegetables were different in spatial variability. There was a close relationship between total and available contents of heavy metals in soil. The contents of Pb and Cd in green vegetables were higher than those of Zn and Cu and exceeded the national sanitation standards for vegetables.

Distribution and uptake pathways of organochlorine pesticides in greenhouse and conventional vegetables.

PubMed

Zhang, Anping; Luo, Wenxiu; Sun, Jianqiang; Xiao, Hang; Liu, Weiping

2015-02-01

The application of greenhouse vegetable cultivation has dramatically expanded worldwide during the last several decades. However, little information is available on the distribution and uptake of pesticides in greenhouse vegetables. To bridge this knowledge gap, the present study was initiated to investigate the distribution and uptake of organochlorine pesticides (OCPs) in vegetables from plastic greenhouse and conventional cultivation methods. The uptake pathways of OCPs were not significantly different between these two cultivation methods. The arithmetic means of OCP concentrations in greenhouse vegetables were higher than those in conventional vegetables, although there was no significant difference. This small difference raised the concern of whether the tiny difference could be magnified to a significant difference by bioaccumulation in the food chain. The issue should be addressed by a well-designed scheme in future studies. Copyright © 2014 Elsevier B.V. All rights reserved.

Dietary patterns and risk of colorectal cancer: a systematic review of cohort studies (2000-2011).

PubMed

Yusof, Afzaninawati Suria; Isa, Zaleha Md; Shah, Shamsul Azhar

2012-01-01

This systematic review of cohort studies aimed to identify any association between specific dietary patterns and risk of colorectal cancer (CRC). Dietary patterns involve complex interactions of food and nutrients summarizing the total diet or key aspects of the diet for a population under study. This review involves 6 cohort studies of dietary patterns and their association with colorectal cancer. An exploratory or a posteriori approach and a hypothesis-oriented or a priori approach were employed to identify dietary patterns. The dietary pattern identified to be protective against CRC was healthy, prudent, fruits and vegetables, fat reduced/diet foods, vegetables/fish/poultry, fruit/wholegrain/dairy, healthy eating index 2005, alternate healthy eating index, Mediterranean score and recommended food score. An elevated risk of CRC was associated with Western diet, pork processed meat, potatoes, traditional meat eating, and refined grain pattern. The Western dietary pattern which mainly consists of red and processed meat and refined grains is associated with an elevated risk of development of CRC. Protective factors against CRC include a healthy or prudent diet, consisting of vegetables, fruits, fish and poultry.

Integrating multiple vegetation indices via an artificial neural network model for estimating the leaf chlorophyll content of Spartina alterniflora under interspecies competition.

PubMed

Liu, Pudong; Shi, Runhe; Zhang, Chao; Zeng, Yuyan; Wang, Jiapeng; Tao, Zhu; Gao, Wei

2017-10-31

The invasive species Spartina alterniflora and native species Phragmites australis display a significant co-occurrence zonation pattern and this co-exist region exerts most competitive situations between these two species, competing for the limited space, directly influencing the co-exist distribution in the future. However, these two species have different growth ratios in this area, which increase the difficulty to detect the distribution situation directly by remote sensing. As chlorophyll content is a key indicator of plant growth and physiological status, the objective of this study was to reduce the effect of interspecies competition when estimating Cab content; we evaluated 79 published representative indices to determine the optimal indices for estimating the chlorophyll a and b (Cab) content. After performing a sensitivity analysis for all 79 spectral indices, five spectral indices were selected and integrated using an artificial neural network (ANN) to estimate the Cab content of different competition ratios: the Gitelson ratio green index, the transformed chlorophyll absorption ratio index/optimized soil-adjusted vegetation index, the modified normalized difference vegetation index, the chlorophyll fluorescence index, and the Vogelmann chlorophyll index. The ANN method yielded better results (R 2  = 0.7110 and RMSE = 8.3829 μg cm -2 ) on average than the best single spectral index (R 2  = 0.6319 and RMSE = 9.3535 μg cm -2 ), representing an increase of 10.78% in R 2 and a decrease of 10.38% in RMSE. Our results indicated that integrating multiple vegetation indices with an ANN can alleviate the impact of interspecies competition and achieve higher estimation accuracy than the traditional approach using a single index.

[Spatial variations of biogenic elements in coastal wetland sediments of the Jiulong River Estuary].

PubMed

Yu, Xiao-Qing; Yang, Jun; Liu, Le-Mian; Tian, Yuan; Yu, Zheng; Wang, Chang-Fu

2012-11-01

To reveal the spatial distribution of biogenic elements and their influencing factors in the typical subtropical coastal wetland, both surface and core sediment samples were collected from the Jiulong River Estuary, southeast China in summer 2009. The biogenic elements including carbon, nitrogen, phosphorus, sulfur (C, N, P, S) were determined by Element Analyzer and Flow Injection Analyzer. The concentrations of TC, TN, TP, and TS were (12.64 +/- 2.66) g x kg(-1), (1.57 +/- 0.29) g x kg(-1), (0.48 +/- 0.06) g x kg(-1), and (2.61 +/- 1.37) g x kg(-1), respectively. Further, these biogenic elements showed a distinct spatial pattern which closely related with the vegetation type and tide level. Values of TC, TN, TP in the surface sediment of mangrove vegetation zones were higher than those in the cord-grass and mudflat zones, while TC, TN, TP concentrations in the high tide level regions were higher than those in the middle and low tide level regions. The TS concentration was the highest in cord-grass vegetation and middle tidal level zones. The TC and TN values in sedimentary core decreased gradually with depth, and they were the highest in the mangrove sites, followed by cord-grass and mudflat sites at the same depth. In mudflat sedimentary core, the average content of TP was the lowest, whereas TS was the highest. Redundancy analysis revealed that vegetation type, pH and tide level were the main factors influencing the distribution of biogenic elements in surface sediments of the Jiulong River Estuary, by explaining 24.0%, 19.0% and 11.6% of total variation in the four biogenic elements (C, N, P and S), respectively.

ALM-FATES: Using dynamic vegetation and demography to capture changes in forest carbon cycling and competition at the global scale

NASA Astrophysics Data System (ADS)

Holm, J. A.; Knox, R. G.; Koven, C.; Riley, W. J.; Bisht, G.; Fisher, R.; Christoffersen, B. O.; Dietze, M.; Chambers, J. Q.

2017-12-01

The inclusion of dynamic vegetation demography in Earth System Models (ESMs) has been identified as a critical step in moving ESMs towards more realistic representations of plant ecology and the processes that govern climatically important fluxes of carbon, energy, and water. Successful application of dynamic vegetation models, and process-based approaches to simulate plant demography, succession, and response to disturbances without climate envelopes at the global scale is a challenging endeavor. We integrated demographic processes using the Functionally-Assembled Terrestrial Ecosystem Simulator (FATES) in the newly developed ACME Land Model (ALM). We then use an ALM-FATES globally gridded simulation for the first time to investigate plant functional type (PFT) distributions and dynamic turnover rates. Initial global simulations successfully include six interacting and competing PFTs (ranging from tropical to boreal, evergreen, deciduous, needleleaf and broadleaf); including more PFTs is planned. Global maps of net primary productivity, leaf area index, and total vegetation biomass by ALM-FATES matched patterns and values when compared to CLM4.5-BGC and MODIS estimates. We also present techniques for PFT parameterization based on the Predictive Ecosystem Analyzer (PEcAn), field based turnover rates, improved PFT groupings based on trait-tradeoffs, and improved representation of multiple canopy positions. Finally, we applied the improved ALM-FATES model at a central Amazon tropical and western U.S. temperate sites and demonstrate improvements in predicted PFT size- and age-structure and regional distribution. Results from the Amazon tropical site investigate the ability and magnitude of a tropical forest to act as a carbon sink by 2100 with a doubling of CO2, while results from the temperate sites investigate the response of forest mortality with increasing droughts.

Historical and current forest and range landscapes in the interior Columbia River basin and portions of the Klamath and Great Basins. Part 1: Linking vegetation patterns and landscape vulnerability to potential insect and pathogen disturbances.

Treesearch

Paul F. Hessburg; Bradley G. Smith; Scott D. Kreiter; Craig A. Miller; R. Brion Salter; Cecilia H. McNicoll; Wendel J. Hann

1999-01-01

Management activities of the 20th century, especially fire exclusion, timber harvest, and domestic livestock grazing, have significantly modified vegetation spatial patterns of forests and ranges in the interior Columbia basin. Compositional patterns as well as patterns of living and dead structure have changed. Dramatic change in vital ecosystem processes such as fire...

Increasing arboreality with altitude: a novel biogeographic dimension

PubMed Central

Scheffers, Brett R.; Phillips, Ben L.; Laurance, William F.; Sodhi, Navjot S.; Diesmos, Arvin; Williams, Stephen E.

2013-01-01

Biodiversity is spatially organized by climatic gradients across elevation and latitude. But do other gradients exist that might drive biogeographic patterns? Here, we show that rainforest's vertical strata provide climatic gradients much steeper than those offered by elevation and latitude, and biodiversity of arboreal species is organized along this gradient. In Philippine and Singaporean rainforests, we demonstrate that rainforest frogs tend to shift up in the rainforest strata as altitude increases. Moreover, a Philippine-wide dataset of frog distributions shows that frog assemblages become increasingly arboreal at higher elevations. Thus, increased arboreality with elevation at broad biogeographic scales mirrors patterns we observed at local scales. Our proposed ‘arboreality hypothesis’ suggests that the ability to exploit arboreal habitats confers the potential for larger geographical distributions because species can shift their location in the rainforest strata to compensate for shifts in temperature associated with elevation and latitude. This novel finding may help explain patterns of species richness and abundance wherever vegetation produces a vertical microclimatic gradient. Our results further suggest that global warming will ‘flatten’ the biodiversity in rainforests by pushing arboreal species towards the cooler and wetter ground. This ‘flattening’ could potentially have serious impacts on forest functioning and species survival. PMID:24026817

Increasing arboreality with altitude: a novel biogeographic dimension.

PubMed

Scheffers, Brett R; Phillips, Ben L; Laurance, William F; Sodhi, Navjot S; Diesmos, Arvin; Williams, Stephen E

2013-11-07

Biodiversity is spatially organized by climatic gradients across elevation and latitude. But do other gradients exist that might drive biogeographic patterns? Here, we show that rainforest's vertical strata provide climatic gradients much steeper than those offered by elevation and latitude, and biodiversity of arboreal species is organized along this gradient. In Philippine and Singaporean rainforests, we demonstrate that rainforest frogs tend to shift up in the rainforest strata as altitude increases. Moreover, a Philippine-wide dataset of frog distributions shows that frog assemblages become increasingly arboreal at higher elevations. Thus, increased arboreality with elevation at broad biogeographic scales mirrors patterns we observed at local scales. Our proposed 'arboreality hypothesis' suggests that the ability to exploit arboreal habitats confers the potential for larger geographical distributions because species can shift their location in the rainforest strata to compensate for shifts in temperature associated with elevation and latitude. This novel finding may help explain patterns of species richness and abundance wherever vegetation produces a vertical microclimatic gradient. Our results further suggest that global warming will 'flatten' the biodiversity in rainforests by pushing arboreal species towards the cooler and wetter ground. This 'flattening' could potentially have serious impacts on forest functioning and species survival.

Factors Impacting Spatial Patterns of Snow Distribution in a Small Catchment near Nome, AK

NASA Astrophysics Data System (ADS)

Chen, M.; Wilson, C. J.; Charsley-Groffman, L.; Busey, R.; Bolton, W. R.

2017-12-01

Snow cover plays an important role in the climate, hydrology and ecological systems of the Arctic due to its influence on the water balance, thermal regimes, vegetation and carbon flux. Thus, snow depth and coverage have been key components in all the earth system models but are often poorly represented for arctic regions, where fine scale snow distribution data is sparse. The snow data currently used in the models is at coarse resolution, which in turn leads to high uncertainty in model predictions. Through the DOE Office of Science Next Generation Ecosystem Experiment, NGEE-Arctic, high resolution snow distribution data is being developed and applied in catchment scale models to ultimately improve representation of snow and its interactions with other model components in the earth system models . To improve these models, it is important to identify key factors that control snow distribution and quantify the impacts of those factors on snow distribution. In this study, two intensive snow depth surveys (1 to 10 meters scale) were conducted for a 2.3 km2 catchment on the Teller road, near Nome, AK in the winter of 2016 and 2017. We used a statistical model to quantify the impacts of vegetation types, macro-topography, micro-topography, and meteorological parameters on measured snow depth. The results show that snow spatial distribution was similar between 2016 and 2017, snow depth was spatially auto correlated over small distance (2-5 meters), but not spatially auto correlated over larger distance (more than 2-5 meters). The coefficients of variation of snow depth was above 0.3 for all the snow survey transects (500-800 meters long). Variation of snow depth is governed by vegetation height, aspect, slope, surface curvature, elevation and wind speed and direction. We expect that this empirical statistical model can be used to estimate end of winter snow depth for the whole watershed and will further develop the model using data from other arctic regions to estimate seasonally dynamic snow coverage and properties for use in catchment scale to pan-Arctic models.

The global distribution of ecosystems in a world without fire.

PubMed

Bond, W J; Woodward, F I; Midgley, G F

2005-02-01

This paper is the first global study of the extent to which fire determines global vegetation patterns by preventing ecosystems from achieving the potential height, biomass and dominant functional types expected under the ambient climate (climate potential). To determine climate potential, we simulated vegetation without fire using a dynamic global-vegetation model. Model results were tested against fire exclusion studies from different parts of the world. Simulated dominant growth forms and tree cover were compared with satellite-derived land- and tree-cover maps. Simulations were generally consistent with results of fire exclusion studies in southern Africa and elsewhere. Comparison of global 'fire off' simulations with landcover and treecover maps show that vast areas of humid C(4) grasslands and savannas, especially in South America and Africa, have the climate potential to form forests. These are the most frequently burnt ecosystems in the world. Without fire, closed forests would double from 27% to 56% of vegetated grid cells, mostly at the expense of C(4) plants but also of C(3) shrubs and grasses in cooler climates. C(4) grasses began spreading 6-8 Ma, long before human influence on fire regimes. Our results suggest that fire was a major factor in their spread into forested regions, splitting biotas into fire tolerant and intolerant taxa.

Prokaryotes in salt marsh sediments of Ria de Aveiro: Effects of halophyte vegetation on abundance and diversity

NASA Astrophysics Data System (ADS)

Oliveira, Vanessa; Santos, Ana L.; Aguiar, Claúdia; Santos, Luisa; Salvador, Ângelo C.; Gomes, Newton C. M.; Silva, Helena; Rocha, Sílvia M.; Almeida, Adelaide; Cunha, Ângela

2012-09-01

The aim of this study was to investigate the influence of monospecific colonization of sediment stands by Spartina maritima or Halimione portulacoides on benthic prokaryote assemblages in a salt marsh located in Ria de Aveiro (Portugal). The distribution of Bacteria, Archaea and sulfate-reducing bacteria (SRB) in sediments with monospecific plant stands and in unvegetated sediments was characterized by Fluorescence In Situ Hybridization (FISH). Total prokaryote abundance (0.4 × 109-1.7 × 109 cells gdw-1) was highest in sediments from the surface layer. The domain Bacteria comprised approximately 40% of total prokaryote communities with the highest percentages occurring in the surface layer. Archaeal cells corresponded to an average of 25% of total prokaryote population, with higher abundance in the vegetation banks, and displaying homogeneous vertical distribution. The relative abundance of SRB represented approximately 3% of total 4', 6-diamidino-2-phenylindole dihydrochloride (DAPI) stained cells at unvegetated sediment and H. portulacoides stand and 7% at S. maritima stand. Headspace solid-phase microextraction (HS-SPME) combined with Comprehensive Two-Dimensional Gas Chromatography-Time-of-Flight Mass Spectrometry (GC × GC-ToFMS) was used to analyse the volatile and semi-volatile fraction of root exudates. A total of 171 compounds were identified and Principal Component Analysis showed a clear separation between the chemical composition (volatile and semi-volatile organic compounds) of the exudates of the two plants. The patterns of vertical distribution and differences in the proportion of SRB and Archaea in the prokaryote communities developing in sediments colonized by Spartina maritima or Halimione portulacoides suggest the existence of plant-specific interactions between halophyte vegetation and estuarine sediment bacteria in Ria de Aveiro salt marshes, exerted via sediment lithology and root-derived exudates.

Controls on the spatial variability of key soil properties: comparing field data with a mechanistic soilscape evolution model

NASA Astrophysics Data System (ADS)

Vanwalleghem, T.; Román, A.; Giraldez, J. V.

2016-12-01

There is a need for better understanding the processes influencing soil formation and the resulting distribution of soil properties. Soil properties can exhibit strong spatial variation, even at the small catchment scale. Especially soil carbon pools in semi-arid, mountainous areas are highly uncertain because bulk density and stoniness are very heterogeneous and rarely measured explicitly. In this study, we explore the spatial variability in key soil properties (soil carbon stocks, stoniness, bulk density and soil depth) as a function of processes shaping the critical zone (weathering, erosion, soil water fluxes and vegetation patterns). We also compare the potential of a geostatistical versus a mechanistic soil formation model (MILESD) for predicting these key soil properties. Soil core samples were collected from 67 locations at 6 depths. Total soil organic carbon stocks were 4.38 kg m-2. Solar radiation proved to be the key variable controlling soil carbon distribution. Stone content was mostly controlled by slope, indicating the importance of erosion. Spatial distribution of bulk density was found to be highly random. Finally, total carbon stocks were predicted using a random forest model whose main covariates were solar radiation and NDVI. The model predicts carbon stocks that are double as high on north versus south-facing slopes. However, validation showed that these covariates only explained 25% of the variation in the dataset. Apparently, present-day landscape and vegetation properties are not sufficient to fully explain variability in the soil carbon stocks in this complex terrain under natural vegetation. This is attributed to a high spatial variability in bulk density and stoniness, key variables controlling carbon stocks. Similar results were obtained with the mechanistic soil formation model MILESD, suggesting that more complex models might be needed to further explore this high spatial variability.

Distinguishing local ecology from regional hydrologic change in a subtropical wetland, Florida Everglades USA

NASA Astrophysics Data System (ADS)

Bernhardt, C. E.; Willard, D. A.

2012-12-01

The Florida Everglades is a subtropical peatland where differences in bedrock topography, water depth, and hydroperiod affect the distribution and composition of vegetation communities. Previous studies have demonstrated that human modification of the natural hydrology and changes in precipitation associated with natural climate variability can alter the distribution wetland vegetation and influence whether a site is accumulating peat or marl. Pollen analysis of sediments from vegetation communities separated by only a few meters, like the ridges and sloughs, demonstrates the strong signature of the local community. However, over decadal to centennial scales, a broader regional climate response is documented in the pollen record. Here, we examine the sedimentary and pollen records from a suite of 42 cores to tease apart local and regional hydrologic patterns in the marl prairie wetland community. The marl prairie community, which covers an area of 190,000 ha, is a short hydroperiod wetland characterized by sparse vegetation and dominated by grasses and sedges. Pollen and geochronologic data from an earlier study suggested that changes in the vegetation (sawgrass marsh to prairie) and sediment type (peat to marl) were tied exclusively to 20th century water management. However, our results show a diverse assemblage of sediment profiles include marl over peat, peat over marl, all peat, and all marl; and, that the onset of marl accumulation is not limited to the 20th century but occurs at several intervals over the last 1700 years. The primary control on substrate type (marl vs. peat) may be local hydrologic and geomorphic features (sinkholes vs depressions) rather than changes in regional hydrology. Pollen evidence from most sites is consistent with our early study and indicates a regional shift to shorter hydroperiod conditions early in the 20th century that are tied to changes in water management. This study reflects the importance of relying on more than just a single core, or single transect of cores, for teasing apart the local and regional effects on peatlands.

Detecting the influence of best management practices on vegetation near ephemeral streams with Landsat data

USGS Publications Warehouse

Rigge, Matthew B.; Smart, Alexander; Wylie, Bruce K.; de Van Kamp, Kendall

2014-01-01

Various best management practices (BMPs) have been implemented on rangelands with the goals of controlling nonpoint source pollution, reducing the impact of livestock in ecologically important riparian areas, and improving grazing distribution. Providing off-stream water sources to livestock in pastures, cross-fencing, and rotational grazing are common rangeland BMPs that have demonstrated success in drawing livestock grazing pressure away from streams. We evaluated the effects of rangeland BMP implementation with six commercial-scale pastures in the northern mixed-grass prairie. Four pastures received a BMP suite consisting of off-stream water, cross-fencing, and deferred-rotation grazing, and two pastures did not receive BMPs. We hypothesized that the BMPs increased the quantity of riparian vegetation cover relative to the conditions in these pastures during the pre-BMP period and to the two pastures that did not receive BMPs. We used a series of 30-m Landsat normalized difference vegetation index (NDVI) images to track the spatial and temporal changes (1984–2010, n = 24) in vegetation cover, to which NDVI has been well correlated. Validation indicated that the remotely sensed signal from in-channel vegetation was representative of ground conditions. The BMP suite was associated with a 15% increase in the in-channel NDVI (0–30 m from stream centerline) and 18% increase in the riparian NDVI (30–180 m from stream center line). Conversely, the in-channel and riparian NDVI of non-BMP pastures declined 30% and 18% over the study period. The majority of change occurred within 2 yr of BMP implementation. The patterns of in-channel NDVI among pastures suggested that BMP implementation likely altered grazing distribution by decreasing the preferential use of riparian and in-channel areas. We demonstrated that satellite imagery time series are useful in retrospectively evaluating the efficacy of conservation practices, providing critical information to guide adaptive management and decision makers.

Comparison of the South Florida Natural System Model with Pre-canal Everglades Hydrology Estimated from Historical Sources

USGS Publications Warehouse

McVoy, Christopher; Park, Winifred A.; Obeysekera, Jayantha

1996-01-01

Preservation and restoration of the remaining Everglades ecosystem is focussed on two aspects: improving upstream water quality and improving 'hydropatterns' - the timing, depth and flow of surface water. Restoration of hydropatterns requires knowledge of the original pre-canal drainage conditions as well as an understanding of the soil, topo-graphic, and vegetation changes that have taken place since canal drainage began in the 1880's. The Natural System Model (NSM), developed by the South Florida Water Management District (SFWMD) and Everglades National Park, uses estimates of pre-drainage vegetation and topography to estimate the pre-drainage hydrologic response of the Everglades. Sources of model uncertainty include: (1) the algorithms, (2) the parameters (particularly those relating to vegetation roughness and evapotranspiration), and (3) errors in the assumed pre-drainage vegetation distribution and pre-drainage topography. Other studies are concentrating on algorithmic and parameter sources of uncertainty. In this study we focus on the NSM output -- predicted hydropattern -- and evaluate this by comparison with all available direct and indirect information on pre-drainage hydropatterns. The unpublished and published literature is being searched exhaustively for observations of water depth, flow direction, flow velocity and hydroperiod, during the period prior and just after drainage (1840-1920). Additionally, a comprehensive map of soils in the Everglades region, prepared in the 1940's by personnel from the University of Florida Agricultural Experiment Station, the U.S. Soil Conservation Service, the U.S. Geological Survey, and the Everglades Drainage District, is being used to identify wetland soils and to infer the spatial distribution of pre-drainage hydrologic conditions. Detailed study of this map and other early soil and vegetation maps in light of the history of drainage activities will reveal patterns of change and possible errors in the input to the NSM. Changes in the wetland soils are important because of their effects on topography (soil subsidence) and in their role as indicators of hydropattern.

Relationship between dietary pattern and cognitive function in elderly patients with type 2 diabetes mellitus.

PubMed

Enomoto, Mari; Yoshii, Hidenori; Mita, Tomoya; Sanke, Haruna; Yokota, Ayako; Yamashiro, Keiko; Inagaki, Noriko; Gosho, Masahiko; Ohmura, Chie; Kudo, Kayo; Watada, Hirotaka; Onuma, Tomio

2015-08-01

To analyse the relationships between dietary patterns and cognitive function in elderly patients with type 2 diabetes mellitus (T2DM). Patients with T2DM completed a 3-day dietary record and Mini-mental State Examination (MMSE). Dietary patterns were identified by factor analysis. The study included 73 patients and identified five dietary patterns, one of which was characterized by high loading for vegetables and fish. A higher consumption of vegetables and fish was significantly associated with improved MMSE score (unadjusted model, model adjusted for age and sex, and model adjusted for age, sex, education, diabetic nephropathy and alcohol consumption), and decreased prevalence of suspected mild dementia (unadjusted model, model adjusted for age and sex). A high score in the vegetables and fish dietary pattern was associated with high MMSE score and low prevalence of suspected mild dementia in elderly patients with T2DM. © The Author(s) 2015.

Ecological feedbacks. Termite mounds can increase the robustness of dryland ecosystems to climatic change.

PubMed

Bonachela, Juan A; Pringle, Robert M; Sheffer, Efrat; Coverdale, Tyler C; Guyton, Jennifer A; Caylor, Kelly K; Levin, Simon A; Tarnita, Corina E

2015-02-06

Self-organized spatial vegetation patterning is widespread and has been described using models of scale-dependent feedback between plants and water on homogeneous substrates. As rainfall decreases, these models yield a characteristic sequence of patterns with increasingly sparse vegetation, followed by sudden collapse to desert. Thus, the final, spot-like pattern may provide early warning for such catastrophic shifts. In many arid ecosystems, however, termite nests impart substrate heterogeneity by altering soil properties, thereby enhancing plant growth. We show that termite-induced heterogeneity interacts with scale-dependent feedbacks to produce vegetation patterns at different spatial grains. Although the coarse-grained patterning resembles that created by scale-dependent feedback alone, it does not indicate imminent desertification. Rather, mound-field landscapes are more robust to aridity, suggesting that termites may help stabilize ecosystems under global change. Copyright © 2015, American Association for the Advancement of Science.

Holocene biome shifts in the East Asian monsoon margin region

NASA Astrophysics Data System (ADS)

Dallmeyer, Anne; Claussen, Martin; Ni, Jian; Wang, Yongbo; Cao, Xianyong; Herzschuh, Ulrike

2013-04-01

East Asia is affected by three major atmospheric circulation systems determining the regional climate and vegetation distribution: The moisture advected by the Indian and East Asian monsoon support the growing of forest in large parts of Eastern China. The influence of the monsoon gets weaker further on the continent yielding a transition of forest to steppe and of steppe to desert in Central East Asia (e.g. Inner Mongolia) where the dry westerly winds prevail. Particularly in these transition zones, vegetation is supposed to be very sensitive to climate change and strong feedbacks are expected in case of climate and vegetation shifts due to large environmental changes (Feng et al., 2006). During mid-Holocene, cyclic variations in the Earth's orbit around the sun led to an enhancement of the Asian monsoon system probably causing strong shifts in the biome distribution. According to reconstructions, the steppe-forest margin moved to the northwest by about 500km (Yu et al., 2000) and the desert area in China and Inner Mongolia was substantially reduced compared to today (Feng et al., 2006). However, in the complex environment of Asia, the locally limited reconstructions may not portray the general vegetation change. To get a systematic overview on the spatial pattern of biome shifts in the Asian monsoon - westerly wind transition zone since mid-Holocene, we use the diagnostic vegetation model BIOME4 and force this model with climate anomalies from different transient Holocene climate simulations performed in coupled atmosphere-ocean-vegetation models. The main aims of this study are to a) get a consistent ensemble of possible changes in biome distribution since the mid-Holocene b) test the robustness of the simulated vegetation changes and quantify the differences between the models, and c) allow for a better comparison of simulated and reconstructed vegetation changes. Preliminary results confirm the general trend seen in the reconstructions. The simulations reveal an expansion of forest for most models and a substantially reduced desert fraction in the transition zone during mid-Holocene. However, the amplitude of the signal and the trend varies for the different climate models. At mid-Holocene, the desert-steppe margin is located further west by approx. 6° in the ensemble mean ranging from 1° to 10° in the different simulations. The forest biomes extend further north-westward by approx. 2° in the ensemble mean ranging from 0° to 4°. In some simulations, the biome distribution shows a strong variability during the last 6000 years and a strong increase of desert starting 500 years before present. In other simulations the biome distribution stays relatively constant until 4500 years before present, afterwards the desert border gradually moves eastward to its present-day position. References: Feng, Z.-D., An, C.B., and Wang, H.B.: Holocene climatic and environmental changes in the arid and semi-arid areas of China: a review. The Holocene 16(1), 119-130, 2006. Yu, G., Chen, X., Ni, J., Cheddadi, R., Guiot, J., Han, H., Harrison, S.P., Huang, C., Ke, M., Kong, Z., Li, S., Li, W., Liew, P., Liu, G., Liu, J., Liu, Q., Liu, K.-B., Prentice, I.C., Qui, W., Ren, G., Song, C., Sugita, S., Sun, X., Tang, L., Van Campo, E., Xia, Y., Xu, Q., Yan, S., Yang, X., Zhao, J., and Zheng, Z.: Palaeovegetation of China: a pollen date-based synthesis for the mid-Holocene and last glacial maximum. J. Biogeogr., 27, 635-664, 2000.

Dietary patterns by cluster analysis in pregnant women: relationship with nutrient intakes and dietary patterns in 7-year-old offspring.

PubMed

Freitas-Vilela, Ana Amélia; Smith, Andrew D A C; Kac, Gilberto; Pearson, Rebecca M; Heron, Jon; Emond, Alan; Hibbeln, Joseph R; Castro, Maria Beatriz Trindade; Emmett, Pauline M

2017-04-01

Little is known about how dietary patterns of mothers and their children track over time. The objectives of this study are to obtain dietary patterns in pregnancy using cluster analysis, to examine women's mean nutrient intakes in each cluster and to compare the dietary patterns of mothers to those of their children. Pregnant women (n = 12 195) from the Avon Longitudinal Study of Parents and Children reported their frequency of consumption of 47 foods and food groups. These data were used to obtain dietary patterns during pregnancy by cluster analysis. The absolute and energy-adjusted nutrient intakes were compared between clusters. Women's dietary patterns were compared with previously derived clusters of their children at 7 years of age. Multinomial logistic regression was performed to evaluate relationships comparing maternal and offspring clusters. Three maternal clusters were identified: 'fruit and vegetables', 'meat and potatoes' and 'white bread and coffee'. After energy adjustment women in the 'fruit and vegetables' cluster had the highest mean nutrient intakes. Mothers in the 'fruit and vegetables' cluster were more likely than mothers in 'meat and potatoes' (adjusted odds ratio [OR]: 2.00; 95% Confidence Interval [CI]: 1.69-2.36) or 'white bread and coffee' (OR: 2.18; 95% CI: 1.87-2.53) clusters to have children in a 'plant-based' cluster. However the majority of children were in clusters unrelated to their mother dietary pattern. Three distinct dietary patterns were obtained in pregnancy; the 'fruit and vegetables' pattern being the most nutrient dense. Mothers' dietary patterns were associated with but did not dominate offspring dietary patterns. © 2016 The Authors. Maternal & Child Nutrition published by John Wiley & Sons Ltd.

Diversity of Forest Litter-Inhabiting Ants Along Elevations in the Wayanad Region of the Western Ghats

PubMed Central

Sabu, Thomas K.; Vineesh, P. J.; Vinod, K.V.

2008-01-01

Litter ant diversity and abundance in relation to biotic and abiotic factors were analyzed at five primary forest sites lying between 300 to 1650 meter above mean sea level in the Wayanad region of the Western Ghats in Kerala, southern India. Ant abundance and species richness peaked at mid-elevations influenced by the presence of favourable physical conditions and abundance of prey resources. Dominance of ants preferring termites and Collembola as prey at sites rich in their specific prey resources indicate the influence of local prey resource availability in determining ant distribution. Dominant species (Tapinoma sp. and Solenopsis sp.) had wider distributions, being present at all elevations. Physical factors (slope of the terrain, rainfall, moisture, humidity, temperature) and prey resource availability (insect larvae, termites, Collembola) influenced ant species abundance at a regional scale, whereas at local scales, site specific variations in the relationship between abundance of ants and prey-predators and physical factors were recorded. The present study highlights the need to consider site-specific abiotic and biotic factors while examining the distribution patterns of litter ants along altitudinal gradients in other regions of the Western Ghats, which is a recognised hot spot of biodiversity with wide regional variation in vegetation types and faunal distribution patterns.

Empirical evidence for multi-scaled controls on wildfire size distributions in California

NASA Astrophysics Data System (ADS)

Povak, N.; Hessburg, P. F., Sr.; Salter, R. B.

2014-12-01

Ecological theory asserts that regional wildfire size distributions are examples of self-organized critical (SOC) systems. Controls on SOC event-size distributions by virtue are purely endogenous to the system and include the (1) frequency and pattern of ignitions, (2) distribution and size of prior fires, and (3) lagged successional patterns after fires. However, recent work has shown that the largest wildfires often result from extreme climatic events, and that patterns of vegetation and topography may help constrain local fire spread, calling into question the SOC model's simplicity. Using an atlas of >12,000 California wildfires (1950-2012) and maximum likelihood estimation (MLE), we fit four different power-law models and broken-stick regressions to fire-size distributions across 16 Bailey's ecoregions. Comparisons among empirical fire size distributions across ecoregions indicated that most ecoregion's fire-size distributions were significantly different, suggesting that broad-scale top-down controls differed among ecoregions. One-parameter power-law models consistently fit a middle range of fire sizes (~100 to 10000 ha) across most ecoregions, but did not fit to larger and smaller fire sizes. We fit the same four power-law models to patch size distributions of aspect, slope, and curvature topographies and found that the power-law models fit to a similar middle range of topography patch sizes. These results suggested that empirical evidence may exist for topographic controls on fire sizes. To test this, we used neutral landscape modeling techniques to determine if observed fire edges corresponded with aspect breaks more often than expected by random. We found significant differences between the empirical and neutral models for some ecoregions, particularly within the middle range of fire sizes. Our results, combined with other recent work, suggest that controls on ecoregional fire size distributions are multi-scaled and likely are not purely SOC. California wildfire ecosystems appear to be adaptive, governed by stationary and non-stationary controls, which may be either exogenous or endogenous to the system.

Stocking rate effects on spatial heterogeneity in vegetation cover in a grazing-resistant grassland

USDA-ARS?s Scientific Manuscript database

Spatial patterns in rangeland vegetation serve as indicators of rangeland condition and are an important component of wildlife habitat. We illustrate the use of very-large-scale aerial photography (VLSA) to quantify spatial patterns in bare soil of the northeastern Colorado shortgrass steppe. Using ...

Short-term vegetation response following mechanical control of saltcedar (Tamarix spp.) on the Virgin River, Nevada, USA

USGS Publications Warehouse

Ostoja, Steven M.; Brooks, Matthew L.; Dudley, Tom; Lee, Steven R.

2014-01-01

and species diversity were very low, suggesting that targets of restoring vegetation to pre-invasion conditions were not met. Longer evaluation periods are needed to adequately evaluate how short-term post-treatment patterns translate to long-term patterns of plant community dynamics.

Patterns in Vegetable Consumption: Implications for Tailored School Meal Interventions

ERIC Educational Resources Information Center

Orlowski, Marietta; Lee, Miryoung; Spears, William; Narayan, Roopsi; Pobocik, Rebecca S.; Kennel, Julie; Krafka, Erin; Patton, Susan

2017-01-01

Background: Vegetable consumption is a challenging behavioral target; consumption rates are below recommended levels and when interventions produce improvements, increases in vegetable consumption are typically a fraction of the change in fruit consumption. We describe vegetable consumption within Ohio school meals and examine how fruit selection,…

Can we grow organic or conventional vegetables sustainably without cover crops?

USDA-ARS?s Scientific Manuscript database

Vegetable and fruit consumption patterns in the United States show that most people need to eat far more fruits and vegetables to meet the current nutritional guidelines for a healthy diet. Following these guidelines would require more than doubling the harvested acreage for fruits and vegetables a...

[Effects of human engineering activities on permafrost active layer and its environment in northern Qinghai-Tibetan plateau].

PubMed

Guo, Zhenggang; Wu, Qingbo; Niu, Fujun

2006-11-01

With disturbed and undisturbed belts during the construction of Qinghai-Tibet highway as test objectives, this paper studied the effects of human engineering activities on the permafrost ecosystem in northern Qinghai-Tibetan plateau. The results showed that the thickness of permafrost active layer was smaller in disturbed than in undisturbed belt, and decreased with increasing altitude in undisturbed belt while no definite pattern was observed in disturbed belt. Different vegetation types had different effects on the thickness of permafrost active layer, being decreased in the order of steppe > shrub > meadow. In the two belts, altitude was the main factor affecting the vertical distribution of soil moisture, but vegetation type was also an important affecting factor if the altitude was similar. Due to the human engineering activities, soil temperature in summer was lower in disturbed than in undisturbed belt.

Pinon and Juniper Field Guide: Asking the Right Questions to Select Appropriate Management Actions

USGS Publications Warehouse

Tausch, R.J.; Miller, R.F.; Roundy, B.A.; Chambers, J.C.

2009-01-01

Pinon-juniper woodlands are an important vegetation type in the Great Basin. Old-growth and open shrub savanna woodlands have been present over much of the last several hundred years. Strong evidence indicates these woodlands have experienced significant tree infilling and major expansion in their distribution since the late 1800s by encroaching into surrounding landscapes once dominated by shrubs and herbaceous vegetation. Both infilling and expansion affects soil resources, plant community structure and composition, water and nutrient cycles, forage production, wildlife habitat, biodiversity, and fire patterns across the landscape. Another impact is the shift from historic fire regimes to larger and more intense wildfires that are increasingly determining the future of this landscape. This publication helps biologists and land managers consider how to look at expansion of woodlands and determine what questions to ask to develop a management strategy, including prescribed fire or other practices.

The influence of natural factors on the spatio-temporal distribution of Oncomelania hupensis.

PubMed

Cheng, Gong; Li, Dan; Zhuang, Dafang; Wang, Yong

2016-12-01

We analyzed the influence of natural factors, such as temperature, rainfall, vegetation and hydrology, on the spatio-temporal distribution of Oncomelania hupensis and explored the leading factors influencing these parameters. The results will provide reference methods and theoretical a basis for the schistosomiasis control. GIS (Geographic Information System) spatial display and analysis were used to describe the spatio-temporal distribution of Oncomelania hupensis in the study area (Dongting Lake in Hunan Province) from 2004 to 2011. Correlation analysis was used to detect the natural factors associated with the spatio-temporal distribution of O. hupensis. Spatial regression analysis was used to quantitatively analyze the effects of related natural factors on the spatio-temporal distribution of snails and explore the dominant factors influencing this parameter. (1) Overall, the spatio-temporal distribution of O. hupensis was governed by the comprehensive effects of natural factors. In the study area, the average density of living snails showed a downward trend, with the exception of a slight rebound in 2009. The density of living snails showed significant spatial clustering, and the degree of aggregation was initially weak but enhanced later. Regions with high snail density and towns with an HH distribution pattern were mostly distributed in the plain areas in the northwestern and inlet and outlet of the lake. (2) There were space-time differences in the influence of natural factors on the spatio-temporal distribution of O. hupensis. Temporally, the comprehensive influence of natural factors on snail distribution increased first and then decreased. Natural factors played an important role in snail distribution in 2005, 2006, 2010 and 2011. Spatially, it decreased from the northeast to the southwest. Snail distributions in more than 20 towns located along the Yuanshui River and on the west side of the Lishui River were less affected by natural factors, whereas relatively larger in areas around the outlet of the lake (Chenglingji) were more affected. (3) The effects of natural factors on the spatio-temporal distribution of O. hupensis were spatio-temporally heterogeneous. Rainfall, land surface temperature, NDVI, and distance from water sources all played an important role in the spatio-temporal distribution of O. hupensis. In addition, due to the effects of the local geographical environment, the direction of the influences the average annual rainfall, land surface temperature, and NDVI had on the spatio-temporal distribution of O. hupensis were all spatio-temporally heterogeneous, and both the distance from water sources and the history of snail distribution always had positive effects on the distribution O. hupensis, but the direction of the influence was spatio-temporally heterogeneous. (4) Of all the natural factors, the leading factors influencing the spatio-temporal distribution of O. hupensis were rainfall and vegetation (NDVI), and the primary factor alternated between these two. The leading role of rainfall decreased year by year, while that of vegetation (NDVI) increased from 2004 to 2011. The spatio-temporal distribution of O. hupensis was significantly influenced by natural factors, and the influences were heterogeneous across space and time. Additionally, the variation in the spatial-temporal distribution of O. hupensis was mainly affected by rainfall and vegetation. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

[Distribution pattern of rare plants along riparian zone and its implication for conservation in Shennongjia area].

PubMed

Jiang, Mingxi; Deng, Hongbing; Cai, Qinghua

2002-11-01

Due to the importance of riparian zone in maintaining and protecting regional biodiversity, more and more ecologists paid their attentions to riparian zone, and had been aware of the important effects of riparian zone in basic study and practical management. In this study, forty sampling belts (10 m x 100 m) parallel to the bank of Xiangxi River at different elevations in Shennongjia area were selected to investigate the riparian vegetation and rare plants. Fourteen species of rare plants were found in riparian zone, accounting for 42.4% of total rare plant species in Shennongjia area. The main distribution range of the fourteen rare plant species was the mixed evergreen and deciduous broadleaved forest at elevation of 1200-1800 m, where species diversity of plant community was the maximum at the moderate elevation. Fourteen rare plant species could be divided into three groups against the elevation, namely low elevation species group, moderate elevation species group, and high elevation group. In the paper, the authors discussed the reasons forming the distribution pattern of rare plant species, and pointed out the important function of riparian zone on rare plant species protection.

Combining satellite data and appropriate objective functions for improved spatial pattern performance of a distributed hydrologic model

NASA Astrophysics Data System (ADS)

Demirel, Mehmet C.; Mai, Juliane; Mendiguren, Gorka; Koch, Julian; Samaniego, Luis; Stisen, Simon

2018-02-01

Satellite-based earth observations offer great opportunities to improve spatial model predictions by means of spatial-pattern-oriented model evaluations. In this study, observed spatial patterns of actual evapotranspiration (AET) are utilised for spatial model calibration tailored to target the pattern performance of the model. The proposed calibration framework combines temporally aggregated observed spatial patterns with a new spatial performance metric and a flexible spatial parameterisation scheme. The mesoscale hydrologic model (mHM) is used to simulate streamflow and AET and has been selected due to its soil parameter distribution approach based on pedo-transfer functions and the build in multi-scale parameter regionalisation. In addition two new spatial parameter distribution options have been incorporated in the model in order to increase the flexibility of root fraction coefficient and potential evapotranspiration correction parameterisations, based on soil type and vegetation density. These parameterisations are utilised as they are most relevant for simulated AET patterns from the hydrologic model. Due to the fundamental challenges encountered when evaluating spatial pattern performance using standard metrics, we developed a simple but highly discriminative spatial metric, i.e. one comprised of three easily interpretable components measuring co-location, variation and distribution of the spatial data. The study shows that with flexible spatial model parameterisation used in combination with the appropriate objective functions, the simulated spatial patterns of actual evapotranspiration become substantially more similar to the satellite-based estimates. Overall 26 parameters are identified for calibration through a sequential screening approach based on a combination of streamflow and spatial pattern metrics. The robustness of the calibrations is tested using an ensemble of nine calibrations based on different seed numbers using the shuffled complex evolution optimiser. The calibration results reveal a limited trade-off between streamflow dynamics and spatial patterns illustrating the benefit of combining separate observation types and objective functions. At the same time, the simulated spatial patterns of AET significantly improved when an objective function based on observed AET patterns and a novel spatial performance metric compared to traditional streamflow-only calibration were included. Since the overall water balance is usually a crucial goal in hydrologic modelling, spatial-pattern-oriented optimisation should always be accompanied by traditional discharge measurements. In such a multi-objective framework, the current study promotes the use of a novel bias-insensitive spatial pattern metric, which exploits the key information contained in the observed patterns while allowing the water balance to be informed by discharge observations.

[Interrelations between plant communities and environmental factors of wetlands and surrounding lands in mid- and lower reaches of Tarim River].

PubMed

Zhao, Ruifeng; Zhou, Huarong; Qian, Yibing; Zhang, Jianjun

2006-06-01

A total of 16 quadrants of wetlands and surrounding lands in the mid- and lower reaches of Tarim River were surveyed, and the data about the characteristics of plant communities and environmental factors were collected and counted. By using PCA (principal component analysis) ordination and regression procedure, the distribution patterns of plant communities and the relationships between the characteristics of plant community structure and environmental factors were analyzed. The results showed that the distribution of the plant communities was closely related to soil moisture, salt, and nutrient contents. The accumulative contribution rate of soil moisture and salt contents in the first principal component accounted for 35.70%, and that of soil nutrient content in the second principal component reached 25.97%. There were 4 types of habitats for the plant community distribution, i. e., fenny--light salt--medium nutrient, moist--medium salt--medium nutrient, mesophytic--medium salt--low nutrient, and medium xerophytic-heavy salt--low nutrient. Along these habitats, swamp vegetation, meadow vegetation, riparian sparse forest, halophytic desert, and salinized shrub were distributed. In the wetlands and surrounding lands of mid- and lower reaches of Tarim River, the ecological dominance of the plant communities was markedly and unitary-linearly correlated with the compound gradient of soil moisture and salt contents. The relationships between species diversity, ecological dominance, and compound gradient of soil moisture and salt contents were significantly accorded to binary-linear regression model.

Demographic analysis of tree colonization in a 20-year-old right-of-way.

PubMed

Mercier, C; Brison, J; Bouchard, A

2001-12-01

Past tree colonization dynamics of a powerline-right-of-way (ROW) corridor in the Haut-Saint-Laurent region of Quebec was studied based on the present age distribution of its tree populations. This colonization study spans 20 years, from 1977 (ROW clearance) to 1996. The sampled quadrats were classified into six vegetation types. Tree colonization dynamics were interpreted in each type, and three distinct patterns were identified. (1) Communities adapted to acidic conditions were heavily colonized by Acer rubrum, at least for the last 12 years. (2) Communities adapted to mesic or to hydric conditions were more intensely colonized in the period 1985-1987 than in the following 9 years; this past success in tree colonization may have been caused by herbicide treatments, which could have facilitated tree establishment by damaging the herbaceous and shrub vegetation. (3) Cattail, vine-raspberry, and reed-dominated communities contained few tree individuals, with almost all trees establishing between 1979 and 1990; those three vegetation types appear as the most resistant to tree invasion in the ROW studied. This study supports the need for an integrated approach in ROW vegetation management, in which the selection of vegetation treatment methods would depend on the tree colonization dynamics in each vegetation type. Minimizing disturbances inflicted on ROW herbaceous and shrub covers should be the central strategy because disturbances jeopardize natural resistance to future tree invasion, except in communities adapted to acidic conditions where the existing vegetation does not prevent invasion by A. rubrum. Many trees are surviving the successive cutting operations by producing new sprouts each time, particularly in communities adapted to mesic and hydric conditions. In these cases, mechanical cutting should be replaced by a one-time stump-killing operation, to avoid repeated and unsuccessful treatments of the same individuals over time.

Effects of ice and floods on vegetation in streams in cold regions: implications for climate change

PubMed Central

Lind, Lovisa; Nilsson, Christer; Weber, Christine

2014-01-01

Riparian zones support some of the most dynamic and species-rich plant communities in cold regions. A common conception among plant ecologists is that flooding during the season when plants are dormant generally has little effect on the survival and production of riparian vegetation. We show that winter floods may also be of fundamental importance for the composition of riverine vegetation. We investigated the effects of ice formation on riparian and in-stream vegetation in northern Sweden using a combination of experiments and observations in 25 reaches, spanning a gradient from ice-free to ice-rich reaches. The ice-rich reaches were characterized by high production of frazil and anchor ice. In a couple of experiments, we exposed riparian vegetation to experimentally induced winter flooding, which reduced the dominant dwarf-shrub cover and led to colonization of a species-rich forb-dominated vegetation. In another experiment, natural winter floods caused by anchor-ice formation removed plant mimics both in the in-stream and in the riparian zone, further supporting the result that anchor ice maintains dynamic plant communities. With a warmer winter climate, ice-induced winter floods may first increase in frequency because of more frequent shifts between freezing and thawing during winter, but further warming and shortening of the winter might make them less common than today. If ice-induced winter floods become reduced in number because of a warming climate, an important disturbance agent for riparian and in-stream vegetation will be removed, leading to reduced species richness in streams and rivers in cold regions. Given that such regions are expected to have more plant species in the future because of immigration from the south, the distribution of species richness among habitats can be expected to show novel patterns. PMID:25505542

Effects of ice and floods on vegetation in streams in cold regions: implications for climate change.

PubMed

Lind, Lovisa; Nilsson, Christer; Weber, Christine

2014-11-01

Riparian zones support some of the most dynamic and species-rich plant communities in cold regions. A common conception among plant ecologists is that flooding during the season when plants are dormant generally has little effect on the survival and production of riparian vegetation. We show that winter floods may also be of fundamental importance for the composition of riverine vegetation. We investigated the effects of ice formation on riparian and in-stream vegetation in northern Sweden using a combination of experiments and observations in 25 reaches, spanning a gradient from ice-free to ice-rich reaches. The ice-rich reaches were characterized by high production of frazil and anchor ice. In a couple of experiments, we exposed riparian vegetation to experimentally induced winter flooding, which reduced the dominant dwarf-shrub cover and led to colonization of a species-rich forb-dominated vegetation. In another experiment, natural winter floods caused by anchor-ice formation removed plant mimics both in the in-stream and in the riparian zone, further supporting the result that anchor ice maintains dynamic plant communities. With a warmer winter climate, ice-induced winter floods may first increase in frequency because of more frequent shifts between freezing and thawing during winter, but further warming and shortening of the winter might make them less common than today. If ice-induced winter floods become reduced in number because of a warming climate, an important disturbance agent for riparian and in-stream vegetation will be removed, leading to reduced species richness in streams and rivers in cold regions. Given that such regions are expected to have more plant species in the future because of immigration from the south, the distribution of species richness among habitats can be expected to show novel patterns.

Opposing environmental gradients govern vegetation zonation in an intermountain playa

USGS Publications Warehouse

Sanderson, J.S.; Kotliar, N.B.; Steingraeber, D.A.

2008-01-01

Vegetation zonation was investigated at an intermountain playa wetland (Mishak Lakes) in the San Luis Valley (SLV) of southern Colorado. Plant composition and abiotic conditions were quantified in six vegetation zones. Reciprocal transplants were performed to test the importance of abiotic factors in governing zonation. Abiotic conditions differed among several vegetation zones. Prolonged inundation led to anaerobic soils in the Eleocharis palustris and the submerged aquatics zones, on the low end of the site's 1.25 m elevation gradient. On the high end of the gradient, soil salinity and sodicity (a measure of exchangeable sodium) were high in the Distichlis spicata zone (electrical conductivity, EC = 5.3 dS/m, sodium absorption ratio, SAR = 44.0) and extreme in the Sarcobatus vermiculatus zone (EC = 21 dS/m, SAR = 274). Transplanted species produced maximum biomass in the zone where they originated, not in any other higher or lower vegetation zone. The greatest overall transplant effect occurred for E. palustris, which experienced a ??? 77% decline in productivity when transplanted to other zones. This study provides evidence that physical factors are a major determinant of vegetation zone composition and distribution across the entire elevation gradient at Mishak Lakes. Patterns at Mishak Lakes arise from counter-directional stress gradients: a gradient from anaerobic to well-oxygenated from basin bottom to upland and a gradient from extremely high salinity to low salinity in the opposing direction. Because abiotic conditions dominate vegetation zonation, restoration of the altered hydrologic regime of this wetland to a natural hydrologic regime may be sufficient to re-establish many of the natural biodiversity functions provided by these wetlands. ?? 2008 The Society of Wetland Scientists.

What Works? Process Evaluation of a School-Based Fruit and Vegetable Distribution Program in Mississippi

ERIC Educational Resources Information Center

Potter, Susan C.; Schneider, Doris; Coyle, Karin K.; May, Gary; Robin, Leah; Seymour, Jenna

2011-01-01

Background: During the 2004-2005 school year, the Mississippi Department of Education, Office of Child Nutrition, initiated a pilot program to distribute free fruit and vegetable snacks to students during the school day. This article describes the first-year implementation of the Mississippi Fruit and Vegetable Pilot Program. Methods: The process…

Interactions between geomorphology and vegetation in the Western Swiss Alps: first investigations

NASA Astrophysics Data System (ADS)

Giaccone, Elisa; Mariéthoz, Grégoire; Lambiel, Christophe

2017-04-01

The influence of earth surface processes can modify the microhabitat conditions and the species richness, composition and distribution patterns of plant communities. It is therefore important to understand how geomorphology affects the distribution of plant species to predict future vegetation evolution in a context of climate change. To better analyse the influence of geomorphology on vegetation growth in the alpine periglacial belt, we are studying various geomorphological processes (e.g. cryoturbation and solifluction), permafrost, nivation and ground surface characteristics at three focus sites of the Vaud Alps (Western Swiss Alps). The sites are located at an altitude range comprised between 2000 and 2600 m a.s.l. The geomorphology is characterized mainly by the presence of small glaciers, large moraine deposits, rock glaciers and debris slopes. Monitoring of the ground surface temperatures, permafrost mapping, vegetation survey and drone flights have been carried out to investigate in detail the environmental variables. Initial results show a heterogeneous vegetation cover depending on time since deglaciation, debris size, ground stability and soil age. Debris pioneer species are present on moraines, rock glaciers and debris slope; grassland are developed in zones not affected by LIA glacier advances or other interfering processes such as avalanches. The high-resolution images obtained from drone flights (5 cm/pixel) allow a detailed study of the granulometry. In order to use such geomorphological information on a wider area of interest, the local data acquired on focus sites have to be spatialized to a regional scale. This is accomplished by developing an approach based on remote sensing and multiple-point geostatistics that performs a semi-automated geomorphological mapping (SAGM). The SAGM is based on a training image composed by a geomorphological map yet existent, an orthophoto, the slope, the aspect, the curvature, the granulometry classification and the NDVI. The SAGM will be first elaborated for the focus sites and will then be extended to the entire Vaud Alps above 2000 m a.s.l. This information will be used to better understand the geomorphology-vegetation interactions and their spatialization.

Combined field/modelling approaches to represent the air-vegetation distribution of benzo[a]pyrene using different vegetation species

NASA Astrophysics Data System (ADS)

Ratola, Nuno; Jiménez-Guerrero, Pedro

2015-04-01

A strategy designed to combine the features of field-based experiments and modelling approaches is presented in this work to assess air-vegetation distribution of benzo(a)pyrene (BaP) in the Iberian Peninsula (IP). Given the lack of simultaneous data in both environmental matrices, a methodology with two main steps was employed. First, evaluating the simulations with the chemistry transport model (CTM) WRF (Weather Research and Forecasting) + CHIMERE data against the European Monitoring and Evaluation Programme (EMEP) network, to test the aptitude of the CTM to replicate the respective atmospheric levels. Then, using modelled concentrations and a method to estimate air levels of BaP from biomonitoring data to compare the performance of different pine species (Pinus pinea, Pinus pinaster, Pinus nigra and Pinus halepensis) to describe the atmospheric evidences. The comparison of modelling vs. biomonitoring has a higher dependence on the location of the sampling points, rather than on the pine species, as some tend to overestimate and others to underestimate BaP concentrations, in most cases regardless of the season. The climatology of the canopy levels of BaP was successfully validated with the concentrations in pine needles (most biases below 26%), however, the model was unable to distinguish between species. This should be taken into consideration in future studies, as biases can rise up to 48%, especially in summer and autumn, the. The comparison with biomonitoring data showed a similar pattern, but with the best results in the warmer months.

Landscape co-evolution and river discharge.

NASA Astrophysics Data System (ADS)

van der Velde, Ype; Temme, Arnaud

2015-04-01

Fresh water is crucial for society and ecosystems. However, our ability to secure fresh water resources under climatic and anthropogenic change is impaired by the complexity of interactions between human society, ecosystems, soils, and topography. These interactions cause landscape properties to co-evolve, continuously changing the flow paths of water through the landscape. These co-evolution driven flow path changes and their effect on river runoff are, to-date, poorly understood. In this presentation we introduce a spatially distributed landscape evolution model that incorporates growing vegetation and its effect on evapotranspiration, interception, infiltration, soil permeability, groundwater-surface water exchange and erosion. This landscape scale (10km2) model is calibrated to evolve towards well known empirical organising principles such as the Budyko curve and Hacks law under different climate conditions. To understand how positive and negative feedbacks within the model structure form complex landscape patterns of forests and peat bogs that resemble observed landscapes under humid and boreal climates, we analysed the effects of individual processes on the spatial distribution of vegetation and river peak and mean flows. Our results show that especially river peak flows and droughts decrease with increasing evolution of the landscape, which is a result that has direct implications for flood management.

Quantifying forest vertical structure to determine bird habitat quality in the Greenbelt Corridor, Denton, TX

NASA Astrophysics Data System (ADS)

Matsubayashi, Shiho

This study presents the integration of light detection and range (LiDAR) and hyperspectral remote sensing to create a three-dimensional bird habitat map in the Greenbelt Corridor of the Elm Fork of the Trinity River. This map permits to examine the relationship between forest stand structure, landscape heterogeneity, and bird community composition. A biannual bird census was conducted at this site during the breeding seasons of 2009 and 2010. Census data combined with the three-dimensional map suggest that local breeding bird abundance, community structure, and spatial distribution patterns are highly influenced by vertical heterogeneity of vegetation surface. For local breeding birds, vertical heterogeneity of canopy surface within stands, connectivity to adjacent forest patches, largest forest patch index, and habitat (vegetation) types proved to be the most influential factors to determine bird community assemblages. Results also highlight the critical role of secondary forests to increase functional connectivity of forest patches. Overall, three-dimensional habitat descriptions derived from integrated LiDAR and hyperspectral data serve as a powerful bird conservation tool that shows how the distribution of bird species relates to forest composition and structure at various scales.

Patch-occupancy models indicate human activity as major determinant of forest elephant Loxodonta cyclotis seasonal distribution in an industrial corridor in Gabon

USGS Publications Warehouse

Buij, R.; McShea, W.J.; Campbell, P.; Lee, M.E.; Dallmeier, F.; Guimondou, S.; Mackaga, L.; Guisseougou, N.; Mboumba, S.; Hines, J.E.; Nichols, J.D.; Alonso, A.

2007-01-01

The importance of human activity and ecological features in influencing African forest elephant ranging behaviour was investigated in the Rabi-Ndogo corridor of the Gamba Complex of Protected Areas in southwest Gabon. Locations in a wide geographical area with a range of environmental variables were selected for patch-occupancy surveys using elephant dung to assess seasonal presence and absence of elephants. Patch-occupancy procedures allowed for covariate modelling evaluating hypotheses for both occupancy in relation to human activity and ecological features, and detection probability in relation to vegetation density. The best fitting models for old and fresh dung data sets indicate that (1) detection probability for elephant dung is negatively related to the relative density of the vegetation, and (2) human activity, such as presence and infrastructure, are more closely associated with elephant distribution patterns than are ecological features, such as the presence of wetlands and preferred fresh fruit. Our findings emphasize the sensitivity of elephants to human disturbance, in this case infrastructure development associated with gas and oil production. Patch-occupancy methodology offers a viable alternative to current transect protocols for monitoring programs with multiple covariates.

Patterns of Twentieth Century Treeline Advance in Alaska: Insights from Dendrochronology and Permanent Plot Studies

NASA Astrophysics Data System (ADS)

Lloyd, A. H.; Fastie, C. L.

2014-12-01

Warming over the last several decades has led to an upward or poleward shift in the distributional limit of trees at sites around the circumboreal north. In our own research in three regions in Alaska, we found evidence for an upward shift in treeline at every site, in the form of a decline in population age with increasing elevation. The prevalence of that particular signature of change suggests that continued expansion of forest vegetation at treeline is likely. But how fast, and how sustained are those changes likely to be in the future? Changing disturbance regimes, non-linear growth responses to warming, and unexplained regional variability in the rate of historical responses to warming all introduce significant uncertainty to projections of future change at treeline. In an effort to compare historical with current patterns of change, we set up permanent plots in each of the sites at which we had reconstructed forest history, tagging each tree and seedling. We resampled these plots more than a decade after the initial measurements, and thus have an opportunity to compare the actual trajectory of change in each plot with the trajectory that we inferred from our dendrochronological reconstructions. At most sites, the observed pattern of change over the last 10-15 years is consistent with the trajectory inferred from dendrochronological studies. Seedling density at treeline and above treeline increased significantly over this time period-- almost doubling (98.6% increase) at treeline plots, and increasing more than 189%, on average, in above treeline plots. The expansion of forest vegetation at treeline has thus continued at an extremely rapid pace. The remeasurements also, however, yielded surprises that could not have been anticipated from the reconstructions at forest history. A severe fire at one of our sites killed most of the seedlings that had established above treeline, and in the years since the fire, aspen-- which is not a common treeline species in Alaska-- has become the dominant woody vegetation both at and above treeline at this site. This suggests that changes in disturbance regime at treeline could have unexpected consequences-- leading to rapid establishment of vegetation types that are not currently common at treeline.

Discriminating between camouflaged targets by their time of detection by a human-based observer assessment method

NASA Astrophysics Data System (ADS)

Selj, G. K.; Søderblom, M.

2015-10-01

Detection of a camouflaged object in natural sceneries requires the target to be distinguishable from its local background. The development of any new camouflage pattern therefore has to rely on a well-founded test methodology - which has to be correlated with the final purpose of the pattern - as well as an evaluation procedure, containing the optimal criteria for i) discriminating between the targets and then eventually ii) for a final rank of the targets. In this study we present results from a recent camouflage assessment trial where human observers were used in a search by photo methodology to assess generic test camouflage patterns. We conducted a study to investigate possible improvements in camouflage patterns for battle dress uniforms. The aim was to do a comparative study of potential, and generic patterns intended for use in arid areas (sparsely vegetated, semi desert). We developed a test methodology that was intended to be simple, reliable and realistic with respect to the operational benefit of camouflage. Therefore we chose to conduct a human based observer trial founded on imagery of realistic targets in natural backgrounds. Inspired by a recent and similar trial in the UK, we developed new and purpose-based software to be able to conduct the observer trial. Our preferred assessment methodology - the observer trial - was based on target recordings in 12 different, but operational relevant scenes, collected in a dry and sparsely vegetated area (Rhodes). The scenes were chosen with the intention to span as broadly as possible. The targets were human-shaped mannequins and were situated identically in each of the scenes to allow for a relative comparison of camouflage effectiveness in each scene. Test of significance, among the targets' performance, was carried out by non-parametric tests as the corresponding time of detection distributions in overall were found to be difficult to parameterize. From the trial, containing 12 different scenes from sparsely vegetated areas we collected detection time's distributions for 6 generic targets through visual search by 148 observers. We found that the different targets performed differently, given by their corresponding time of detection distributions, within a single scene. Furthermore, we gained an overall ranking over all the 12 scenes by performing a weighted sum over all scenes, intended to keep as much of the vital information on the targets' signature effectiveness as possible. Our results show that it was possible to measure the targets performance relatively to another also when summing over all scenes. We also compared our ranking based on our preferred criterion (detection time) with a secondary (probability of detection) to assess the sensitivity of a final ranking based upon the test set-up and evaluation criterion. We found our observer-based approach to be well suited regarding its ability to discriminate between similar targets and to assign numeric values to the observed differences in performance. We believe our approach will be well suited as a tool whenever different aspects of camouflage are to be evaluated and understood further.

Changes in Species Diversity Patterns and Spatial Heterogeneity during the Secondary Succession of Grassland Vegetation on the Loess Plateau, China.

PubMed

Sun, Caili; Chai, Zongzheng; Liu, Guobin; Xue, Sha

2017-01-01

Analyzing the dynamic patterns of species diversity and spatial heterogeneity of vegetation in grasslands during secondary succession could help with the maintenance and management of these ecosystems. Here, we evaluated the influence of secondary succession on grassland plant diversity and spatial heterogeneity of abandoned croplands on the Loess Plateau (China) during four phases of recovery: 1-5, 5-10, 10-20, and 20-30 years. The species composition and dominance of the grassland vegetation changed markedly during secondary succession and formed a clear successional series, with the species assemblage dominated by Artemisia capillaris → Heteropappus altaicus→ A. sacrorum . The diversity pattern was one of low-high-low, with diversity peaking in the 10-20 year phase, thus corresponding to a hump-backed model in which maximum diversity occurring at the intermediate stages. A spatially aggregated pattern prevailed throughout the entire period of grassland recovery; this was likely linked to the dispersal properties of herbaceous plants and to high habitat heterogeneity. We conclude that natural succession was conducive to the successful recovery of native vegetation. From a management perspective, native pioneer tree species should be introduced about 20 years after abandoning croplands to accelerate the natural succession of grassland vegetation.

Changes in Species Diversity Patterns and Spatial Heterogeneity during the Secondary Succession of Grassland Vegetation on the Loess Plateau, China

PubMed Central

Sun, Caili; Chai, Zongzheng; Liu, Guobin; Xue, Sha

2017-01-01

Analyzing the dynamic patterns of species diversity and spatial heterogeneity of vegetation in grasslands during secondary succession could help with the maintenance and management of these ecosystems. Here, we evaluated the influence of secondary succession on grassland plant diversity and spatial heterogeneity of abandoned croplands on the Loess Plateau (China) during four phases of recovery: 1–5, 5–10, 10–20, and 20–30 years. The species composition and dominance of the grassland vegetation changed markedly during secondary succession and formed a clear successional series, with the species assemblage dominated by Artemisia capillaris→ Heteropappus altaicus→ A. sacrorum. The diversity pattern was one of low–high–low, with diversity peaking in the 10–20 year phase, thus corresponding to a hump-backed model in which maximum diversity occurring at the intermediate stages. A spatially aggregated pattern prevailed throughout the entire period of grassland recovery; this was likely linked to the dispersal properties of herbaceous plants and to high habitat heterogeneity. We conclude that natural succession was conducive to the successful recovery of native vegetation. From a management perspective, native pioneer tree species should be introduced about 20 years after abandoning croplands to accelerate the natural succession of grassland vegetation. PMID:28900433

Climate-biomes, pedo-biomes and pyro-biomes: which world view explains the tropical forest - savanna boundary in South America?

NASA Astrophysics Data System (ADS)

Langan, Liam; Higgins, Steven; Scheiter, Simon

2015-04-01

Elucidating the drivers of broad vegetation formations improves our understanding of earth system functioning. The biome, defined primarily by the dominance of a particular growth strategy, is commonly employed to group vegetation into similar units. Predicting tropical forest and savanna biome boundaries in South America has proven difficult. Process based DGVMs (Dynamic global vegetation models) are our best tool to simulate vegetation patterns, make predictions for future changes and test theory, however, many DGVMs fail to accurately simulate the spatial distribution or indeed presence of the South American savanna biome which can result in large differences in modelled ecosystem structural properties. Evidence suggests fire plays a significant role in mediating these forest and savanna biome boundaries, however, fire alone does not appear to be sufficient to predict these boundaries in South America using DGVMs hinting at the presence of one or more missing environmental factors. We hypothesise that soil depth, which affects plant available water by determining maximum storage potential and influences temporal availability, may be one of these missing environmental factors. To test our hypothesis we use a novel vegetation model, the aDGVM2. This model has been specifically designed to allow plant trait strategies, constrained by trade-offs between traits, evolve based on the abiotic and biotic conditions where the resulting community trait suites are emergent properties of model dynamics. Furthermore it considers root biomass in multiple soil layers and therefore allows the consideration of alternative rooting strategies, which in turn allows us to explore in more detail the role of soil hydraulic factors in controlling biome boundary distributions. We find that changes in soil depth, interacting with fire, affect the relative dominance of tree and grass strategies and thus the presence and spatial distribution of forest and savanna biomes in South America. Using the ISRIC-WISE soil depth dataset we show that applying spatially variable soil depth, in contrast to globally fixed soil depth, improves the accuracy with which we predict the South American savanna biome distribution when compared to multiple contemporary biome maps and that the emergence of the savanna biome results in markedly different ecosystem structural properties such as tree height, tree cover and above ground biomass. Many of these areas are capable of supporting forest and savanna biome states and have been deemed bi-stable areas, we show that, in these bi-stable areas the emergent tree community trait suite differs markedly between forest and savanna biome states.

Community structure and elevational diversity patterns of soil Acidobacteria.

PubMed

Zhang, Yuguang; Cong, Jing; Lu, Hui; Li, Guangliang; Qu, Yuanyuan; Su, Xiujiang; Zhou, Jizhong; Li, Diqiang

2014-08-01

Acidobacteria is one of the most dominant and abundant phyla in soil, and was believed to have a wide range of metabolic and genetic functions. Relatively little is known about its community structure and elevational diversity patterns. We selected four elevation gradients from 1000 to 2800 m with typical vegetation types of the northern slope of Shennongjia Mountain in central China. The vegetation types were evergreen broadleaved forest, deciduous broadleaved forest, coniferous forest and sub-alpine shrubs. We analyzed the soil acidobacterial community composition, elevational patterns and the relationship between Acidobacteria subdivisions and soil enzyme activities by using the 16S rRNA meta-sequencing technique and multivariate statistical analysis. The result found that 19 known subdivisions as well as an unclassified phylotype were presented in these forest sites, and Subdivision 6 has the highest number of detectable operational taxonomic units (OTUs). A significant single peak distribution pattern (P<0.05) between the OTU number and the elevation was observed. The Jaccard and Bray-Curtis index analysis showed that the soil Acidobacteria compositional similarity significantly decreased (P<0.01) with the increase in elevation distance. Mantel test analysis showed the most of the soil Acidobacteria subdivisions had the significant relationship (P<0.01) with different soil enzymes. Therefore, soil Acidobacteria may be involved in different ecosystem functions in global elemental cycles. Partial Mantel tests and CCA analysis showed that soil pH, soil temperature and plant diversity may be the key factors in shaping the soil Acidobacterial community structure. Copyright © 2014. Published by Elsevier B.V.

Modeling the directional reflectance from complete homogeneous vegetation canopies with various leaf-orientation distributions

NASA Technical Reports Server (NTRS)

Kimes, D. S.

1984-01-01

The directional-reflectance distributions of radiant flux from homogeneous vegetation canopies with greater than 90 percent ground cover are analyzed with a radiative-transfer model. The model assumes that the leaves consist of small finite planes with Lambertian properties. Four theoretical canopies with different leaf-orientation distributions were studied: erectophile, spherical, planophile, and heliotropic canopies. The directional-reflectance distributions from the model closely resemble reflectance distributions measured in the field. The physical scattering mechanisms operating in the model explain the variations observed in the reflectance distributions as a function of leaf-orientation distribution, solar zenith angle, and leaf transmittance and reflectance. The simulated reflectance distribution show unique characteristics for each canopy. The basic understanding of the physical scattering properties of the different canopy geometries gained in this study provide a basis for developing techniques to infer leaf-orientation distributions of vegetation canopies from directional remote-sensing measurements.

Spatial patterns of large natural fires in Sierra Nevada wilderness areas

USGS Publications Warehouse

Collins, B.M.; Kelly, M.; van Wagtendonk, J.W.; Stephens, S.L.

2007-01-01

The effects of fire on vegetation vary based on the properties and amount of existing biomass (or fuel) in a forest stand, weather conditions, and topography. Identifying controls over the spatial patterning of fire-induced vegetation change, or fire severity, is critical in understanding fire as a landscape scale process. We use gridded estimates of fire severity, derived from Landsat ETM+ imagery, to identify the biotic and abiotic factors contributing to the observed spatial patterns of fire severity in two large natural fires. Regression tree analysis indicates the importance of weather, topography, and vegetation variables in explaining fire severity patterns between the two fires. Relative humidity explained the highest proportion of total sum of squares throughout the Hoover fire (Yosemite National Park, 2001). The lowest fire severity corresponded with increased relative humidity. For the Williams fire (Sequoia/Kings Canyon National Parks, 2003) dominant vegetation type explains the highest proportion of sum of squares. Dominant vegetation was also important in determining fire severity throughout the Hoover fire. In both fires, forest stands that were dominated by lodgepole pine (Pinus contorta) burned at highest severity, while red fir (Abies magnifica) stands corresponded with the lowest fire severities. There was evidence in both fires that lower wind speed corresponded with higher fire severity, although the highest fire severity in the Williams fire occurred during increased wind speed. Additionally, in the vegetation types that were associated with lower severity, burn severity was lowest when the time since last fire was fewer than 11 and 17 years for the Williams and Hoover fires, respectively. Based on the factors and patterns identified, managers can anticipate the effects of management ignited and naturally ignited fires at the forest stand and the landscape levels. ?? 2007 Springer Science+Business Media, Inc.

Effects of land use pattern on soil water in revegetation watersheds in semi-arid Chinese Loess Plateau

NASA Astrophysics Data System (ADS)

Yang, Lei; Chen, Liding; Wei, Wei

2017-04-01

Soil water stored below rainfall infiltration depth is a reliable water resource for plant growth in arid and semi-arid regions. For decreasing serious soil erosion, large-scale human-introduced vegetation restoration was initiated in Chinese Loess Plateau in late 1990s. However, these activities may result in excessive water consumption and soil water deficit if no appropriate scientific guidance were offered. This in turn impacts the regional ecological restoration and sustainable management of water resources. In this study, soil water content data in depth of 0-5 m was obtained by long-term field observation and geostatistical method in 6 small watersheds covered with different land use pattern. Profile characteristics and spatial-temporal patterns of soil water were compared between different land use types, hillslopes, and watersheds. The results showed that: (1) Introduced vegetation consumed excessive amount of water when compared with native grassland and farmland, and induced temporally stable soil desiccation in depth of 0-5 m. The introduced vegetation decreased soil water content to levels lower than the reference value representing no human impact in all soil layers. (2) The analysis of differences in soil water at hillslope and watershed scales indicated that land use determined the spatial and temporal variability of soil water. Soil water at watershed scale increased with the increasing area of farmland, and decreased with increasing percentage of introduced vegetation. Land use structure determined the soil water condition and land use pattern determined the spatial-temporal variability of soil water at watershed scale. (3) Large-scale revegetation with introduced vegetation diminished the spatial heterogeneity of soil water at different scales. Land use pattern adjustment could be used to improve the water resources management and maintain the sustainability of vegetation restoration.

Monitoring Urban Greenness Dynamics Using Multiple Endmember Spectral Mixture Analysis

PubMed Central

Gan, Muye; Deng, Jinsong; Zheng, Xinyu; Hong, Yang; Wang, Ke

2014-01-01

Urban greenness is increasingly recognized as an essential constituent of the urban environment and can provide a range of services and enhance residents’ quality of life. Understanding the pattern of urban greenness and exploring its spatiotemporal dynamics would contribute valuable information for urban planning. In this paper, we investigated the pattern of urban greenness in Hangzhou, China, over the past two decades using time series Landsat-5 TM data obtained in 1990, 2002, and 2010. Multiple endmember spectral mixture analysis was used to derive vegetation cover fractions at the subpixel level. An RGB-vegetation fraction model, change intensity analysis and the concentric technique were integrated to reveal the detailed, spatial characteristics and the overall pattern of change in the vegetation cover fraction. Our results demonstrated the ability of multiple endmember spectral mixture analysis to accurately model the vegetation cover fraction in pixels despite the complex spectral confusion of different land cover types. The integration of multiple techniques revealed various changing patterns in urban greenness in this region. The overall vegetation cover has exhibited a drastic decrease over the past two decades, while no significant change occurred in the scenic spots that were studied. Meanwhile, a remarkable recovery of greenness was observed in the existing urban area. The increasing coverage of small green patches has played a vital role in the recovery of urban greenness. These changing patterns were more obvious during the period from 2002 to 2010 than from 1990 to 2002, and they revealed the combined effects of rapid urbanization and greening policies. This work demonstrates the usefulness of time series of vegetation cover fractions for conducting accurate and in-depth studies of the long-term trajectories of urban greenness to obtain meaningful information for sustainable urban development. PMID:25375176

Wildfire patterns and landscape changes in Mediterranean oak woodlands.

PubMed

Guiomar, N; Godinho, S; Fernandes, P M; Machado, R; Neves, N; Fernandes, J P

2015-12-01

Fire is infrequent in the oak woodlands of southern Portugal (montado) but large and severe fires affected these agro-forestry systems in 2003-2005. We hypothesised transition from forest to shrubland as a fire-driven process and investigated the links between fire incidence and montado change to other land cover types, particularly those related with the presence of pioneer communities (generically designed in this context as "transitions to early-successional communities"). We present a landscape-scale framework for assessing the probability of transition from montado to pioneer communities, considering three sets of explanatory variables: montado patterns in 1990 and prior changes from montado to early-successional communities (occurred between 1960 and 1990), fire patterns, and spatial factors. These three sets of factors captured 78.2% of the observed variability in the transitions from montado to pioneer vegetation. The contributions of fire patterns and spatial factors were high, respectively 60.6% and 43.4%, the influence of montado patterns and former changes in montado being lower (34.4%). The highest amount of explained variation in the occurrence of transitions from montado to early-successional communities was related to the pure effect of fire patterns (19.9%). Low spatial connectedness in montado landscape can increase vulnerability to changes, namely to pioneer vegetation, but the observed changes were mostly explained by fire characteristics and spatial factors. Among all metrics used to characterize fire patterns and extent, effective mesh size provided the best modelling results. Transitions from montado to pioneer communities are more likely in the presence of high values of the effective mesh size of total burned area. This cross-boundary metric is an indicator of the influence of large fires in the distribution of the identified transitions and, therefore, we conclude that the occurrence of large fires in montado increases its probability of transition to shrubland. Copyright © 2015 Elsevier B.V. All rights reserved.

NEMA, a functional-structural model of nitrogen economy within wheat culms after flowering. II. Evaluation and sensitivity analysis.

PubMed

Bertheloot, Jessica; Wu, Qiongli; Cournède, Paul-Henry; Andrieu, Bruno

2011-10-01

Simulating nitrogen economy in crop plants requires formalizing the interactions between soil nitrogen availability, root nitrogen acquisition, distribution between vegetative organs and remobilization towards grains. This study evaluates and analyses the functional-structural and mechanistic model of nitrogen economy, NEMA (Nitrogen Economy Model within plant Architecture), developed for winter wheat (Triticum aestivum) after flowering. NEMA was calibrated for field plants under three nitrogen fertilization treatments at flowering. Model behaviour was investigated and sensitivity to parameter values was analysed. Nitrogen content of all photosynthetic organs and in particular nitrogen vertical distribution along the stem and remobilization patterns in response to fertilization were simulated accurately by the model, from Rubisco turnover modulated by light intercepted by the organ and a mobile nitrogen pool. This pool proved to be a reliable indicator of plant nitrogen status, allowing efficient regulation of nitrogen acquisition by roots, remobilization from vegetative organs and accumulation in grains in response to nitrogen treatments. In our simulations, root capacity to import carbon, rather than carbon availability, limited nitrogen acquisition and ultimately nitrogen accumulation in grains, while Rubisco turnover intensity mostly affected dry matter accumulation in grains. NEMA enabled interpretation of several key patterns usually observed in field conditions and the identification of plausible processes limiting for grain yield, protein content and root nitrogen acquisition that could be targets for plant breeding; however, further understanding requires more mechanistic formalization of carbon metabolism. Its strong physiological basis and its realistic behaviour support its use to gain insights into nitrogen economy after flowering.

Albedo climatology for European land surfaces retrieved from AVHRR data (1990-2014) and its spatial and temporal analysis from green-up to vegetation senescence

NASA Astrophysics Data System (ADS)

Sütterlin, M.; Stöckli, R.; Schaaf, C. B.; Wunderle, S.

2016-07-01

Satellite-based, long-term records of surface albedo characterization that accurately capture spatial and temporal patterns are essential to develop climate models and to monitor the impact of land use changes on the terrestrial energy and water balance. This study presents the first Bidirectional Reflectance Distribution Function (BRDF) and albedo data set derived from the Advanced Very High Resolution Radiometer (AVHRR) Local Area Coverage reflectance data acquired on board National Oceanic and Atmospheric Administration and Meteorological Operational platforms from 1990 to 2014 over Europe. The objectives of this paper are to describe the data set's surface albedo climatology and anomalies in the visible, near-infrared, and shortwave broadbands for the growing season months of May to September in order to facilitate utilization of the data by the climate modeling communities. The results demonstrate that the AVHRR BRDF and albedo data have temporal and spatial patterns that are appropriate for the underlying predominant land cover type and accurately reflect the associated climate variation. Visible and near-infrared broadband albedo anomalies are found to be contrasting in most years, and their spatial distributions depict responses of vegetation to climate events (e.g., heat waves). Visible albedo of crops and near-infrared albedo of pastures show a higher interannual variation than respective albedos of other snow-free land covers, while the interannual standard deviations are found to be lower than 0.015. Our findings indicate the importance of taking into account the spectrally distinct variability of surface albedo when analyzing its complex spatiotemporal dynamics in climate-related research.

Global-scale analysis of vegetation indices for moderate resolution monitoring of terrestrial vegetation

NASA Astrophysics Data System (ADS)

Huete, Alfredo R.; Didan, Kamel; van Leeuwen, Willem J. D.; Vermote, Eric F.

1999-12-01

Vegetation indices have emerged as important tools in the seasonal and inter-annual monitoring of the Earth's vegetation. They are radiometric measures of the amount and condition of vegetation. In this study, the Sea-viewing Wide Field-of-View sensor (SeaWiFS) is used to investigate coarse resolution monitoring of vegetation with multiple indices. A 30-day series of SeaWiFS data, corrected for molecular scattering and absorption, was composited to cloud-free, single channel reflectance images. The normalized difference vegetation index (NDVI) and an optimized index, the enhanced vegetation index (EVI), were computed over various 'continental' regions. The EVI had a normal distribution of values over the continental set of biomes while the NDVI was skewed toward higher values and saturated over forested regions. The NDVI resembled the skewed distributions found in the red band while the EVI resembled the normal distributions found in the NIR band. The EVI minimized smoke contamination over extensive portions of the tropics. As a result, major biome types with continental regions were discriminable in both the EVI imagery and histograms, whereas smoke and saturation considerably degraded the NDVI histogram structure preventing reliable discrimination of biome types.

Vegetation of wetlands of the prairie pothole region

USGS Publications Warehouse

Kantrud, H.A.; Millar, J.B.; Van Der Valk, A.G.; van der Valk, A.

1989-01-01

Five themes dominate the literature dealing with the vegetation of palustrine and lacustrine wetlands of the prairie pothole region: environmental conditions (water or moisture regime, salinity), agricultural disturbances (draining, grazing, burning, sedimentation, etc.), vegetation dynamics, zonation patterns, and classification of the wetlands.The flora of a prairie wetland is a function of its water regime, salinity, and disturbance by man. Within a pothole, water depth and duration determines distribution of species. In potholes deep enough to have standing water even during droughts, the central zone will be dominated by submersed species (open water). In wetlands that go dry during periods of drought or annually, the central zone will be dominated by either tall emergent species (deep marsh) or midheight emergents (shallow marsh), respectively. Potholes that are only flooded briefly in the spring are dominated by grasses, sedges, and forbs (wet meadow). Within a pothole, the depth of standing water in the deepest, usually central, part of the basin determines how many zones will be present. Lists of species associated with different water regimes and salinity levels are presented.Disturbances due to agricultural activities have impacted wetlands throughout the region. Drainage has eliminated many potholes, particularly in the southern and eastern parts of the region. Grazing, mowing, and burning have altered the composition of pothole vegetation. The composition of different vegetation types impacted by grazing, haying, and cultivation is presented in a series of tables. Indirect impacts of agriculture (increased sediment, nutrient, and pesticide inputs) are widespread over the region, but their impacts on the vegetation have never been studied.Because of the periodic droughts and wet periods, many palustrine and lacustrine wetlands undergo vegetation cycles associated with water-level changes produced by these wet-dry cycles. Periods of above normal precipitation can raise water levels high enough to drown out emergent vegetation or produce 'eat outs' due to increases in the size of muskrat populations that accompany periods of high water. The elimination of emergents creates a lake marsh dominated by submersed vegetation. During the next drought when the marsh bottom is exposed by receding water levels (a drawdown), seeds of emergents and mudflat annuals in the soil (the seed bank) germinate (the dry marsh stage). When the marsh refloods, ending the dry marsh stage, the emergents survive and spread vegetatively. This is the regenerating marsh. This stage continues until high water again eliminates the emergents, starting the next degenerating stage.Zonation patterns are conspicuous because each zone often is dominated by a single species that has a lifeform different from those in adjacent zones. The species composition of each zone is a function of its environment (water or moisture regime, salinity, and disturbance history). Within a zone it may take a year or more for species composition to adjust to a change of environmental conditions. These lags sometimes result in abnormal zonation patterns, particularly after a change in water level.Classification of prairie wetlands is more difficult than for most other wetland type, because of these vegetation cycles. Early attempts to classify prairie wetlands did not take the dynamic nature of their vegetation into account. Stewart and Kantrud (1971) developed a classification system for prairie potholes that recognized different phases of vegetation zones dominated by deep marsh species. It used the composition of the vegetation in the deepest part (zone) of a pothole as an indicator of its water-level regime and water chemistry. The application of the national wetland classification system of Cowardin et al. (1979) to potholes is also discussed, and lists of species that characterize the various dominance types associated with the subclasses in this system are presented.

Landscape heterogeneity shapes predation in a newly restored predator-prey system.

PubMed

Kauffman, Matthew J; Varley, Nathan; Smith, Douglas W; Stahler, Daniel R; MacNulty, Daniel R; Boyce, Mark S

2007-08-01

Because some native ungulates have lived without top predators for generations, it has been uncertain whether runaway predation would occur when predators are newly restored to these systems. We show that landscape features and vegetation, which influence predator detection and capture of prey, shape large-scale patterns of predation in a newly restored predator-prey system. We analysed the spatial distribution of wolf (Canis lupus) predation on elk (Cervus elaphus) on the Northern Range of Yellowstone National Park over 10 consecutive winters. The influence of wolf distribution on kill sites diminished over the course of this study, a result that was likely caused by territorial constraints on wolf distribution. In contrast, landscape factors strongly influenced kill sites, creating distinct hunting grounds and prey refugia. Elk in this newly restored predator-prey system should be able to mediate their risk of predation by movement and habitat selection across a heterogeneous risk landscape.

Landscape heterogeneity shapes predation in a newly restored predator-prey system

USGS Publications Warehouse

Kauffman, M.J.; Varley, N.; Smith, D.W.; Stahler, D.R.; MacNulty, D.R.; Boyce, M.S.

2007-01-01

Because some native ungulates have lived without top predators for generations, it has been uncertain whether runaway predation would occur when predators are newly restored to these systems. We show that landscape features and vegetation, which influence predator detection and capture of prey, shape large-scale patterns of predation in a newly restored predator-prey system. We analysed the spatial distribution of wolf (Canis lupus) predation on elk (Cervus elaphus) on the Northern Range of Yellowstone National Park over 10 consecutive winters. The influence of wolf distribution on kill sites diminished over the course of this study, a result that was likely caused by territorial constraints on wolf distribution. In contrast, landscape factors strongly influenced kill sites, creating distinct hunting grounds and prey refugia. Elk in this newly restored predator-prey system should be able to mediate their risk of predation by movement and habitat selection across a heterogeneous risk landscape. ?? 2007 Blackwell Publishing Ltd/CNRS.