Science.gov

Sample records for modeling vegetation diversity

  1. Capturing Vegetation Diversity in the Ent Terrestrial Biosphere Model

    NASA Astrophysics Data System (ADS)

    Kiang, N. Y.; Haralick, R. M.; Cook, B.; Aleinov, I. D.

    2013-12-01

    We present preliminary results from data mining to develop parameter sets and global vegetation structure datasets to set boundary conditions for the Ent Terrestrial Biosphere Model (Ent TBM) for improved representation of diversity and to propagate uncertainty in simulations of land carbon dynamics in the 20th century and under future climate change. The Ent TBM is the only dynamic global vegetation model (DGVM) developed for coupling with general circulation models (GCMs) to account for the height structure of mixed canopies, including a canopy radiative transfer scheme that accounts for foliage clumping in dynamically changing canopies. It is flexibly programmed to incorporate any number of "plant functional types" (PFTs). It is now a coupled component of the ModelE2 version of the NASA Goddard Institute for Space Studies (GISS) general circulation model (GCM). We demonstrate a data mining method, linear manifold clustering, to be used with several very recently compiled large databases of plant traits and phenology combined with climate and satellite data, to identify new PFT groupings, and also conduct customized parameter fits of PFT traits already defined in Ent. These parameter sets are used together with satellite-derived global forest height structure and land cover derived from a combination of satellite and inventory sources and bioclimatic relations to provide a new estimate and uncertainty bounds on vegetation biomass carbon stocks. These parameter sets will also be used to reproduce atmospheric CO2 time series over the flask observational period, to evaluate the impact of improved representation of vegetation dynamics on soil carbon stocks, and finally to produce a projection of the land carbon sink under future climate change. This research is timely in taking advantage of new, globally ranging vegetation databases, satellite-derived forest heights, and the advanced framework of the Ent TBM. It will advance understanding of and reduce uncertainty in

  2. Tropical Tree Trait Diversity Enhances Forest Biomass Resilience in a Dynamic Global Vegetation Model

    NASA Astrophysics Data System (ADS)

    Sakschewski, B.; Kirsten, T.; von Bloh, W.; Poorter, L.; Pena-Claros, M.; Boit, A.

    2016-12-01

    Functional diversity of ecosystems has been found to increase ecosystem functions and therefore enhance ecosystem resilience against environmental stressors. However, global carbon-cycle and biosphere models still classify the global vegetation into a relatively small number of distinct plant functional types (PFT) with constant features over space and time. Therefore, those models might underestimate the resilience and adaptive capacity of natural vegetation under climate change by ignoring positive effects that functional diversity might bring about. We diversified a set a of selected tree traits in a dynamic global vegetation model (LPJmL). In the new subversion, called LPJmL-FIT, Amazon region biomass stocks and forest structure appear significantly more resilient against climate change. Enhanced tree trait diversity enables the simulated rainforests to adjust to new environmental conditions via ecological sorting. These results may stimulate a new debate on the value of biodiversity for climate change mitigation.

  3. Palaeo plant diversity in subtropical Africa - ecological assessment of a conceptual model of climate-vegetation interaction

    NASA Astrophysics Data System (ADS)

    Groner, V. P.; Claussen, M.; Reick, C.

    2015-10-01

    We critically reassess a conceptual model here, dealing with the potential effect of plant diversity on climate-vegetation feedback, and we provide an improved version adjusted to plant types that prevailed during the African Humid Period (AHP). Our work contributes to the understanding of the timing and abruptness of vegetation decline at the end of the AHP, investigated by various working groups during the past 2 decades using a wide range of model and palaeo-proxy reconstruction approaches. While some studies indicated an abrupt collapse of vegetation at the end of the AHP, others suggested a gradual decline. Claussen et al. (2013) introduced a new aspect in the discussion, proposing that plant diversity in terms of moisture requirements could affect the strength of climate-vegetation feedback. In a conceptual model study, the authors illustrated that high plant diversity could stabilize an ecosystem, whereas a reduction in plant diversity might allow for an abrupt regime shift under gradually changing environmental conditions. In the light of recently published pollen data and the current state of ecological literature, the conceptual model by Claussen et al. (2013) reproduces the main features of different plant types interacting together with climate, but it does not capture the reconstructed diversity of AHP vegetation. Especially tropical gallery forest taxa, indirectly linked to local precipitation, are not appropriately represented. With a new model version adjusted to AHP vegetation, we can simulate a diverse mosaic-like environment as reconstructed from pollen, and we observe a stabilizing effect of high functional diversity on vegetation cover and precipitation. Sensitivity studies with different combinations of plant types highlight the importance of plant composition on system stability, and the stabilizing or destabilizing potential a single plant type may inherit. The model's simplicity limits its application; however, it provides a useful tool to

  4. Global vegetation model diversity and the risks of climate-driven ecosystem shifts

    SciTech Connect

    Bond-Lamberty, Benjamin

    2013-11-08

    Climate change is modifying global biogeochemical cycles, and is expected to exert increasingly large effects in the future. How these changes will in turn affect and interact with the structure and function of particular ecosystems is unclear, however, both because of scientific uncertainties and the very diversity of global vegetation models in use. Writing in Environmental Research Letters, Warszawski et al. (1) aggregate results from a group of models, across a range of emissions scenarios and climate data, to investigate these risks. Although the models frequently disagree about which specific regions are at risk, they consistently predict a greater chance of ecosystem restructuring with more warming; this risk roughly doubles between 2 and 3 °C increases in global mean temperature. The innovative work of Warszawski et al. represents an important first step towards fully consistent multi-model, multi-scenario assessments of the future risks to global ecosystems.

  5. Remote sensing Penman-Monteith model to estimate catchment evapotranspiration considering the vegetation diversity

    NASA Astrophysics Data System (ADS)

    Li, Fawen; Cao, Runxiang; Zhao, Yong; Mu, Dongjing; Fu, Changfeng; Ping, Feng

    2017-01-01

    A new method for calculating evaporation is proposed, using the Penman-Monteith (P-M) model with remote sensing. This paper achieved the effective estimation to daily evapotranspiration in the Ziya river catchment by using the P-M model based on MODIS remote sensing leaf area index and respectively estimated plant transpiration and soil evaporation by using coefficient of soil evaporation. This model divided catchment into seven different sub-regions which are prairie, meadow, grass, shrub, broad-leaved forest, cultivated vegetation, and coniferous forest through thoroughly considering the vegetation diversity. Furthermore, optimizing and calibrating parameters based on each sub-region and analyzing spatio-temporal variation rules of the model main parameters which are coefficient of soil evaporation f and maximum stomatal conductance g sx . The results indicate that f and g sx calibrated by model are basically consistent with measured data and have obvious spatio-temporal distribution characteristics. The monthly average evapotranspiration value of simulation is 37.96 mm/mon which is close to the measured value with 33.66 mm/mon and the relative error of simulation results in each subregion are within 11 %, which illustrates that simulated values and measured values fit well and the precision of model is high. In addition, plant transpiration and soil evaporation account for about 84.64 and 15.36 % respectively in total evapotranspiration, which means the difference between values of them is large. What is more, this model can effectively estimate the green water resources in basin and provide effective technological support for water resources estimation.

  6. The role of biodiversity for the carbon cycle: Implementation of functional diversity in a dynamic vegetation model

    NASA Astrophysics Data System (ADS)

    Sakschewski, Boris; Boit, Alice; von Bloh, Werner; Rammig, Anja; Thonicke, Kirsten

    2013-04-01

    Most dynamic global vegetation models (DGVMs) condense natural plant diversity to plant functional types (PFTs). A single PFT usually represents a whole biome, e.g. the PFT "tropical broadleaved evergreen tree" and its constant set of functional trait parameters covers entire regions in the model. This approach minimizes functional diversity and neglects the effects of functional diversity on the modeled vegetation and carbon dynamics. Our work aims to overcome this limitation and extend functional diversity in the vegetation model LPJmL to explore the role of biodiversity in climate change mitigation. Our approach improves the representation of biodiversity in the model by incorporating the natural ranges and eco-physiological interrelations of relevant plant traits. Empirical data on plant traits is provided by the TRY data base (www.try-db.org) and the ROBIN project (www.robinproject.info). A first sensitivity analysis revealed that simulated carbon stocks are very stable under a large range of trait combinations. However, several model output variables appeared highly sensitive to small changes of plant trait parameters and thus the introduction of trait ranges requires several improvements of the PFT concept of LPJmL. One possible way of improvement is to implement missing plant-trait tradeoffs, which will be used to simulate the growth of individual plants with flexible parameter combinations at the landscape scale. Our improved model will enable for the simulation of local competition and complementarity of individual plants which, according to their trait values and ranges, can then be categorized into a much broader variety of PFTs. This modeling approach will allow for investigating the role of bio- and functional diversity in the global carbon cycle as well as in regional vegetation dynamics.

  7. Palaeo plant diversity in subtropical Africa - ecological assessment of a conceptual model of climate-vegetation interaction

    NASA Astrophysics Data System (ADS)

    Groner, V. P.; Claussen, M.; Reick, C.

    2015-07-01

    We here critically re-assess a conceptual model dealing with the potential effect of plant diversity on climate-vegetation feedback, and provide an improved version adjusted to plant types that prevailed during the African Humid Period (AHP). Our work contributes to the understanding of the timing and abruptness of vegetation decline at the end of the AHP, investigated by various working groups during the past two decades using a wide range of model and palaeoproxy reconstruction approaches. While some studies indicated an abrupt collapse of vegetation at the end of the AHP, others suggested a gradual decline. Claussen et al. (2013) introduced a new aspect in the discussion, proposing that plant diversity in terms of moisture requirements could affect the strength of climate-vegetation feedback. In a conceptual model study, the authors illustrated that high plant diversity could stabilize an ecosystem, whereas a reduction in plant diversity might allow for an abrupt regime shift under gradually changing environmental conditions. Based on recently published pollen data and the current state of ecological literature, we evaluate the representation of climate-vegetation feedback in this conceptual approach, and put the suggested conclusions into an ecological context. In principle, the original model reproduces the main features of different plant types interacting together with climate although vegetation determinants other than precipitation are neglected. However, the model cannot capture the diversity of AHP vegetation. Especially tropical gallery forest taxa, indirectly linked to local precipitation, are not appropriately represented. In order to fill the gaps in the description of plant types regarding AHP diversity, we modify the original model in four main aspects. First, the growth ranges in terms of moisture requirements are extended by upper limits to represent full environmental envelopes. Second, data-based AHP plant types replace the hypothetical plant

  8. Leaf and stem economics spectra drive diversity of functional plant traits in a dynamic global vegetation model.

    PubMed

    Sakschewski, Boris; von Bloh, Werner; Boit, Alice; Rammig, Anja; Kattge, Jens; Poorter, Lourens; Peñuelas, Josep; Thonicke, Kirsten

    2015-01-22

    Functional diversity is critical for ecosystem dynamics, stability and productivity. However, dynamic global vegetation models (DGVMs) which are increasingly used to simulate ecosystem functions under global change, condense functional diversity to plant functional types (PFTs) with constant parameters. Here, we develop an individual- and trait-based version of the DGVM LPJmL (Lund-Potsdam-Jena managed Land) called LPJmL- flexible individual traits (LPJmL-FIT) with flexible individual traits) which we apply to generate plant trait maps for the Amazon basin. LPJmL-FIT incorporates empirical ranges of five traits of tropical trees extracted from the TRY global plant trait database, namely specific leaf area (SLA), leaf longevity (LL), leaf nitrogen content (Narea ), the maximum carboxylation rate of Rubisco per leaf area (vcmaxarea), and wood density (WD). To scale the individual growth performance of trees, the leaf traits are linked by trade-offs based on the leaf economics spectrum, whereas wood density is linked to tree mortality. No preselection of growth strategies is taking place, because individuals with unique trait combinations are uniformly distributed at tree establishment. We validate the modeled trait distributions by empirical trait data and the modeled biomass by a remote sensing product along a climatic gradient. Including trait variability and trade-offs successfully predicts natural trait distributions and achieves a more realistic representation of functional diversity at the local to regional scale. As sites of high climatic variability, the fringes of the Amazon promote trait divergence and the coexistence of multiple tree growth strategies, while lower plant trait diversity is found in the species-rich center of the region with relatively low climatic variability. LPJmL-FIT enables to test hypotheses on the effects of functional biodiversity on ecosystem functioning and to apply the DGVM to current challenges in ecosystem management from local

  9. Establishing quantitative relations between mammalian communities, climate regimes, and vegetation density - A diversity-based reference model and case study

    NASA Astrophysics Data System (ADS)

    Hertler, Christine; Wolf, Dominik; Bruch, Angela; Märker, Michael

    2013-04-01

    A considerable diversity of hominin taxa is described from the Pleistocene of sub-Saharan Africa. Inner-African range expansions of these taxa are primarily addressed by morphological comparisons of the hominin specimens and systematic interpretation of the results. Considering hominin expansion patterns as being at least co-determined by ecology and environment requires an assessment of respective features of paleo-communities as well as features of the environments with which they are associated. Challenges in validation and integration of reconstructions of hominin environments and ecologies can be met with well-organized recent reference models. Modelling the present day situation permits to assess relevant variables and to establish interactions among them on a quantitative basis. In a next step such a model can be applied to classify hominin paleoenvironments, for which not all data sources are available. An example for this approach is introduced here. In order to characterize hominin environments in sub-Saharan Africa, we assessed sets of variables for composition, structure and diversity of the large mammal communities, climate (temperature and precipitation), and vegetation in African national parks. These data are applied to analyse correlations between faunal communities and their environments on a quantitative basis. While information on large mammal communities is frequently available for hominin localities and regional climate features are addressed on the basis of abiotic proxies, information on paleoflora and vegetation is mostly lacking for the Plio-Pleistocene in sub-Saharan Africa. A quantitative reference model therefore offers new options for reconstructions. A recent reference model moreover permits to quantify descriptive terms like 'savanna'. We will introduce a reference model for sub-Saharan Africa and demonstrate its application in the reconstruction of hominin paleoenvironments. The corresponding quantitative characterization of

  10. FIADB vegetation diversity and structure indicator (VEG)

    Treesearch

    Bethany K. Schulz; Kevin. Dobelbower

    2012-01-01

    The Vegetation Diversity and Structure (VEG) Indicator is a suite of measurements including an inventory of vascular plants on an extensive systematic network of forest plots across the United States. This network is a subset of the standard forest inventory plots established by the U.S. Forest Service Forest Inventory and Analysis program. The VEG indicator provides...

  11. Mapping diverse vegetation with multichannel radar images

    NASA Technical Reports Server (NTRS)

    Ford, J. P.; Wickland, D. E.; Ocampo, A.; Sharitz, R. R.

    1986-01-01

    Airborne-SAR, SIR-A, Seasat SAR, and Landsat TM images of the Savannah River Plant, a gently sloping area of South Carolina covered with diverse vegetation, are presented and briefly characterized. Preliminary results indicate that multiple-polarization images constructed from the airborne-SAR data give some indication of forest density and understory growth but do not permit discrimination between evergreen and deciduous forests. Heat-tolerant vegetation growing on sand bars in streams bearing thermal effluents from nuclear reactors on the site is found to have a distinguishing polarization signature.

  12. Opposing Responses of Bird Functional Diversity to Vegetation Structural Diversity in Wet and Dry Forest

    PubMed Central

    York, Alan; Swan, Matthew; Christie, Fiona; Di Stefano, Julian

    2016-01-01

    Disturbance regimes are changing worldwide, and the consequences for ecosystem function and resilience are largely unknown. Functional diversity (FD) provides a surrogate measure of ecosystem function by capturing the range, abundance and distribution of trait values in a community. Enhanced understanding of the responses of FD to measures of vegetation structure at landscape scales is needed to guide conservation management. To address this knowledge gap, we used a whole-of-landscape sampling approach to examine relationships between bird FD, vegetation diversity and time since fire. We surveyed birds and measured vegetation at 36 landscape sampling units in dry and wet forest in southeast Australia during 2010 and 2011. Four uncorrelated indices of bird FD (richness, evenness, divergence and dispersion) were derived from six bird traits, and we investigated responses of these indices and species richness to both vertical and horizontal vegetation diversity using linear mixed models. We also considered the extent to which the mean and diversity of time since fire were related to vegetation diversity. Results showed opposing responses of FD to vegetation diversity in dry and wet forest. In dry forest, where fire is frequent, species richness and two FD indices (richness and dispersion) were positively related to vertical vegetation diversity, consistent with theory relating to environmental variation and coexistence. However, in wet forest subject to infrequent fire, the same three response variables were negatively associated with vertical diversity. We suggest that competitive dominance by species results in lower FD as vegetation diversity increases in wet forest. The responses of functional evenness were opposite to those of species richness, functional richness and dispersion in both forest types, highlighting the value of examining multiple FD metrics at management-relevant scales. The mean and diversity of time since fire were uncorrelated with vegetation

  13. Opposing Responses of Bird Functional Diversity to Vegetation Structural Diversity in Wet and Dry Forest.

    PubMed

    Sitters, Holly; York, Alan; Swan, Matthew; Christie, Fiona; Di Stefano, Julian

    2016-01-01

    Disturbance regimes are changing worldwide, and the consequences for ecosystem function and resilience are largely unknown. Functional diversity (FD) provides a surrogate measure of ecosystem function by capturing the range, abundance and distribution of trait values in a community. Enhanced understanding of the responses of FD to measures of vegetation structure at landscape scales is needed to guide conservation management. To address this knowledge gap, we used a whole-of-landscape sampling approach to examine relationships between bird FD, vegetation diversity and time since fire. We surveyed birds and measured vegetation at 36 landscape sampling units in dry and wet forest in southeast Australia during 2010 and 2011. Four uncorrelated indices of bird FD (richness, evenness, divergence and dispersion) were derived from six bird traits, and we investigated responses of these indices and species richness to both vertical and horizontal vegetation diversity using linear mixed models. We also considered the extent to which the mean and diversity of time since fire were related to vegetation diversity. Results showed opposing responses of FD to vegetation diversity in dry and wet forest. In dry forest, where fire is frequent, species richness and two FD indices (richness and dispersion) were positively related to vertical vegetation diversity, consistent with theory relating to environmental variation and coexistence. However, in wet forest subject to infrequent fire, the same three response variables were negatively associated with vertical diversity. We suggest that competitive dominance by species results in lower FD as vegetation diversity increases in wet forest. The responses of functional evenness were opposite to those of species richness, functional richness and dispersion in both forest types, highlighting the value of examining multiple FD metrics at management-relevant scales. The mean and diversity of time since fire were uncorrelated with vegetation

  14. Modelling vegetated dune landscapes

    NASA Astrophysics Data System (ADS)

    Baas, A. C. W.; Nield, J. M.

    2007-03-01

    This letter presents a self-organising cellular automaton model capable of simulating the evolution of vegetated dunes with multiple types of plant response in the environment. It can successfully replicate hairpin, or long-walled, parabolic dunes with trailing ridges as well as nebkha dunes with distinctive deposition tails. Quantification of simulated landscapes with eco-geomorphic state variables and subsequent cluster analysis and PCA yields a phase diagram of different types of coastal dunes developing from blow-outs as a function of vegetation vitality. This diagram indicates the potential sensitivity of dormant dune fields to reactivation under declining vegetation vitality, e.g. due to climatic changes. Nebkha simulations with different grid resolutions demonstrate that the interaction between the (abiotic) geomorphic processes and the biological vegetation component (life) introduces a characteristic length scale on the resultant landforms that breaks the typical self-similar scaling of (un-vegetated) bare-sand dunes.

  15. Expanding the Range of Plant Functional Diversity Represented in Global Vegetation Models: Towards Lineage-based Plant Functional Types

    NASA Astrophysics Data System (ADS)

    Still, C. J.; Griffith, D.; Edwards, E.; Forrestel, E.; Lehmann, C.; Anderson, M.; Craine, J.; Pau, S.; Osborne, C.

    2014-12-01

    Variation in plant species traits, such as photosynthetic and hydraulic properties, can indicate vulnerability or resilience to climate change, and feed back to broad-scale spatial and temporal patterns in biogeochemistry, demographics, and biogeography. Yet, predicting how vegetation will respond to future environmental changes is severely limited by the inability of our models to represent species-level trait variation in processes and properties, as current generation process-based models are mostly based on the generalized and abstracted concept of plant functional types (PFTs) which were originally developed for hydrological modeling. For example, there are close to 11,000 grass species, but most vegetation models have only a single C4 grass and one or two C3 grass PFTs. However, while species trait databases are expanding rapidly, they have been produced mostly from unstructured research, with a focus on easily researched traits that are not necessarily the most important for determining plant function. Additionally, implementing realistic species-level trait variation in models is challenging. Combining related and ecologically similar species in these models might ameliorate this limitation. Here we argue for an intermediate, lineage-based approach to PFTs, which draws upon recent advances in gene sequencing and phylogenetic modeling, and where trait complex variations and anatomical features are constrained by a shared evolutionary history. We provide an example of this approach with grass lineages that vary in photosynthetic pathway (C3 or C4) and other functional and structural traits. We use machine learning approaches and geospatial databases to infer the most important environmental controls and climate niche variation for the distribution of grass lineages, and utilize a rapidly expanding grass trait database to demonstrate examples of lineage-based grass PFTs. For example, grasses in the Andropogoneae are typically tall species that dominate wet and

  16. Modelling of vegetation volumes

    NASA Technical Reports Server (NTRS)

    Vanzyl, J. J.; Papas, C. H.; Engheta, N.; Elachi, C.

    1985-01-01

    The purpose is to describe work that is being done to find theoretical models to describe radar backscatter from vegetation layers. The geometry of the problem is shown. The information that one would like to find through the application of the results of these models would include: the thickness of the layer; the absorption in the layer (i.e., density, moisture content, and biomass); the geometry of the scatterers (i.e., shape and orientation); how much of the received power is due to volume scattering only; and a way to enhance the ratio of scattering that has some interaction with the ground surface. The proposed ways to find this information are discussed.

  17. Thermal Vegetation Canopy Model Studies.

    DTIC Science & Technology

    1981-08-01

    D I Prepared for Headquarters, Department of the ArmyS Washington, D. C 20314 ’ip4 Under Project No. 4A762730AT42, Task A4, Work Unit 003 (Contract...K.J., Nguyen, D., and Link, L.E. 1981. "Thermal Vegetation Canopy Model Studies," Technical Report EL-81-6, prepared by Colorado State University in...VEGETATION CANOPY MODEL STUDIES PART 1: INTRODUCTION 1. This technical report is the last of a series of reports prepared on scene radiation dynamics

  18. High herbivore density associated with vegetation diversity in interglacial ecosystems.

    PubMed

    Sandom, Christopher J; Ejrnæs, Rasmus; Hansen, Morten D D; Svenning, Jens-Christian

    2014-03-18

    The impact of large herbivores on ecosystems before modern human activities is an open question in ecology and conservation. For Europe, the controversial wood-pasture hypothesis posits that grazing by wild large herbivores supported a dynamic mosaic of vegetation structures at the landscape scale under temperate conditions before agriculture. The contrasting position suggests that European temperate vegetation was primarily closed forest with relatively small open areas, at most impacted locally by large herbivores. Given the role of modern humans in the world-wide decimations of megafauna during the late Quaternary, to resolve this debate it is necessary to understand herbivore-vegetation interactions before these losses. Here, a synthetic analysis of beetle fossils from Great Britain shows that beetles associated with herbivore dung were better represented during the Last Interglacial (132,000-110,000 y B.P., before modern human arrival) than in the early Holocene (10,000-5,000 y B.P.). Furthermore, beetle assemblages indicate closed and partially closed forest in the early Holocene but a greater mixture of semiopen vegetation and forest in the Last Interglacial. Hence, abundant and diverse large herbivores appear to have been associated with high structural diversity of vegetation before the megafauna extinctions at the end of the Pleistocene. After these losses and in the presence of modern humans, large herbivores generally were less abundant, and closed woodland was more prevalent in the early Holocene. Our findings point to the importance of the formerly rich fauna of large herbivores in sustaining structurally diverse vegetation in the temperate forest biome and provide support for recent moves toward rewilding-based conservation management.

  19. High herbivore density associated with vegetation diversity in interglacial ecosystems

    PubMed Central

    Sandom, Christopher J.; Ejrnæs, Rasmus; Hansen, Morten D. D.; Svenning, Jens-Christian

    2014-01-01

    The impact of large herbivores on ecosystems before modern human activities is an open question in ecology and conservation. For Europe, the controversial wood–pasture hypothesis posits that grazing by wild large herbivores supported a dynamic mosaic of vegetation structures at the landscape scale under temperate conditions before agriculture. The contrasting position suggests that European temperate vegetation was primarily closed forest with relatively small open areas, at most impacted locally by large herbivores. Given the role of modern humans in the world-wide decimations of megafauna during the late Quaternary, to resolve this debate it is necessary to understand herbivore–vegetation interactions before these losses. Here, a synthetic analysis of beetle fossils from Great Britain shows that beetles associated with herbivore dung were better represented during the Last Interglacial (132,000–110,000 y B.P., before modern human arrival) than in the early Holocene (10,000–5,000 y B.P.). Furthermore, beetle assemblages indicate closed and partially closed forest in the early Holocene but a greater mixture of semiopen vegetation and forest in the Last Interglacial. Hence, abundant and diverse large herbivores appear to have been associated with high structural diversity of vegetation before the megafauna extinctions at the end of the Pleistocene. After these losses and in the presence of modern humans, large herbivores generally were less abundant, and closed woodland was more prevalent in the early Holocene. Our findings point to the importance of the formerly rich fauna of large herbivores in sustaining structurally diverse vegetation in the temperate forest biome and provide support for recent moves toward rewilding-based conservation management. PMID:24591633

  20. Changes in vegetation diversity caused by artificial recharge

    USGS Publications Warehouse

    Van Hylckama, T. E. A.

    1979-01-01

    Efforst to increase the rate of artificial recharge through basins often necessitates scrapping and ditching before and during operations. Such operations can result in more or less drastic changes in vegetation (depending on what was there before), characterized by diminisched numbers of species and lowered diversity. Two examples, one from Texas and one from the Netherlands are presented showing how similar treatments cause similar changes in two completely difference plant communities. ?? 1979 Dr. W. Junk b.v. - Publishers.

  1. Riparian area harvesting impacts on vegetation composition and diversity

    Treesearch

    Katherine Elliott; James M. Vose

    2016-01-01

    In the southern Appalachians USA, the boundaries of riparian areas are often hard to define. Vegetation is often used as a riparian indicator and plays a key role in protecting water resources, but adequate knowledge of floristic responses to riparian disturbances is lacking. Our objective was to quantify floristic composition and diversity of the riparian communities ...

  2. Modeling Antibody Diversity.

    ERIC Educational Resources Information Center

    Baker, William P.; Moore, Cathy Ronstadt

    1998-01-01

    Understanding antibody structure and function is difficult for many students. The rearrangement of constant and variable regions during antibody differentiation can be effectively simulated using a paper model. Describes a hands-on laboratory exercise which allows students to model antibody diversity using readily available resources. (PVD)

  3. Modeling Antibody Diversity.

    ERIC Educational Resources Information Center

    Baker, William P.; Moore, Cathy Ronstadt

    1998-01-01

    Understanding antibody structure and function is difficult for many students. The rearrangement of constant and variable regions during antibody differentiation can be effectively simulated using a paper model. Describes a hands-on laboratory exercise which allows students to model antibody diversity using readily available resources. (PVD)

  4. Plant functional diversity enhances associations of soil fungal diversity with vegetation and soil in the restoration of semiarid sandy grassland.

    PubMed

    Zuo, Xiaoan; Wang, Shaokun; Lv, Peng; Zhou, Xin; Zhao, Xueyong; Zhang, Tonghui; Zhang, Jing

    2016-01-01

    The trait-based approach shows that plant functional diversity strongly affects ecosystem properties. However, few empirical studies show the relationship between soil fungal diversity and plant functional diversity in natural ecosystems. We investigated soil fungal diversity along a restoration gradient of sandy grassland (mobile dune, semifixed dune, fixed dune, and grassland) in Horqin Sand Land, northern China, using the denaturing gradient gel electrophoresis of 18S rRNA and gene sequencing. We also examined associations of soil fungal diversity with plant functional diversity reflected by the dominant species' traits in community (community-weighted mean, CWM) and the dispersion of functional trait values (FD is). We further used the structure equation model (SEM) to evaluate how plant richness, biomass, functional diversity, and soil properties affect soil fungal diversity in sandy grassland restoration. Soil fungal richness in mobile dune and semifixed dune was markedly lower than those of fixed dune and grassland (P < 0.05). Soil fungal richness was positively associated with plant richness, biomass, CWM plant height, and soil gradient aggregated from the principal component analysis, but SEM results showed that plant richness and CWM plant height determined by soil properties were the main factors exerting direct effects. Soil gradient increased fungal richness through indirect effect on vegetation rather than direct effect. The negative indirect effect of FDis on soil fungal richness was through its effect on plant biomass. Our final SEM model based on plant functional diversity explained nearly 70% variances of soil fungal richness. Strong association of soil fungal richness with the dominant species in the community supported the mass ratio hypothesis. Our results clearly highlight the role of plant functional diversity in enhancing associations of soil fungal diversity with community structure and soil properties in sandy grassland ecosystems.

  5. 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.

  6. A Riparian Vegetation Ecophysiological Response Model

    Treesearch

    Jeffrey P. Leighton; Roland J. Risser

    1989-01-01

    A mathematical model is described that relates mature riparian vegetation ecophysiological response to changes in stream level. This model was developed to estimate the physiological response of riparian vegetation to reductions in streamflow. Field data from two sites on the North Fork of the Kings River were used in the model development. The physiological response...

  7. Next generation dynamic global vegetation models: learning from community ecology

    NASA Astrophysics Data System (ADS)

    Scheiter, Simon; Higgins, Steven; Langan, Liam

    2013-04-01

    Dynamic global vegetation models are a powerful tool to project the past, current and future distribution of vegetation and associated water and carbon fluxes. However, most models are limited by how they define vegetation and by their simplistic representation of competition. We discuss how concepts from community assembly theory and coexistence theory can help to improve vegetation models. We further present a new trait- and individual-based dynamic vegetation model (the aDGVM2) that allows each individual plant to adopt a unique combination of trait values. These traits define how each individual plant grows and competes with other plants under given environmental conditions. The performance of individual plants in turn drives the assembly of a plant community. A genetic optimisation algorithm is used to simulate the inheritance of traits and different levels of reproductive isolation between individuals. Together these model properties allow the assembly of plant communities that are well adapted to a site's biotic and abiotic conditions. Simulated communities can be classified into different plant functional types or biome types by using trait data bases. We illustrate that the aDGVM2 can simulate (1) how environmental conditions and changes in these conditions influence the trait spectra of assembled plant communities, (2) that fire selects for traits that enhance fire protection and reduces trait diversity, and (3) the emergence of communities dominated by life history strategies that are suggestive of colonisation-competition trade-offs. The aDGVM2 deals with functional diversity and competition fundamentally differently from current dynamic vegetation models. We argue that this approach will yield novel insights as to how vegetation may respond to climate change and we believe that it could foster fruitful collaborations between research communities that focus on plant functional traits, plant competition, plant physiology, systems ecology and earth system

  8. Modeling vegetative filter performance with VFSMOD

    Treesearch

    Matthew J. Helmers; Dean E. Eisenhauer; Michael G. Dosskey; Thomas G. Franti

    2002-01-01

    The model VFSMOD was used to investigate the effect of varying watershed characteristics and buffer dimensions on the sediment trapping efficiency of vegetative filters. This investigation allows for a better understanding of how watershed characteristics, buffer dimensions, and storm characteristics impact the performance of vegetative filters. Using VFSMOD,...

  9. WATER DIVERSION MODEL

    SciTech Connect

    J.B. Case

    1999-12-21

    The distribution of seepage in the proposed repository will be highly variable due in part to variations in the spatial distribution of percolations. The performance of the drip shield and the backfill system may divert the water flux around the waste packages to the invert. Diversion will occur along the drift surface, within the backfill, at the drip shield, and at the Waste Package (WP) surface, even after the drip shield and WP have been breached by corrosion. The purpose and objective of this Analysis and Modeling Report (AMR) are to develop a conceptual model and constitutive properties for bounding the volume and rate of seepage water that flows around the drip shield (CRWMS M&O 1999c). This analysis model is to be compatible with the selected repository conceptual design (Wilkins and Heath, 1999) and will be used to evaluate the performance of the Engineered Barrier System (EBS), and to provide input to the EBS Water Distribution and Removal Model. This model supports the Engineered Barrier System (EBS) postclosure performance assessment for the Site Recommendation (SR). This document characterizes the hydrological constitutive properties of the backfill and invert materials (Section 6.2) and a third material that represents a mixture of the two. These include the Overton Sand which is selected as a backfill (Section 5.2), crushed tuff which is selected as the invert (Section 5.1), and a combined material (Sections 5.9 and 5.10) which has retention and hydraulic conductivity properties intermediate to the selected materials for the backfill and the invert. The properties include the grain size distribution, the dry bulk density and porosity, the moisture retention, the intrinsic permeability, the relative permeability, and the material thermal properties. The van Genuchten relationships with curve fit parameters are used to define the basic retention relationship of moisture potential to volumetric moisture content, and the basic relationship of unsaturated

  10. Beyond the Diversity Crisis Model: Decentralized Diversity Planning and Implementation

    ERIC Educational Resources Information Center

    Williams, Damon A.

    2008-01-01

    This article critiques the diversity crises model of diversity planning in higher education and presents a decentralized diversity planning model. The model is based on interviews with the nation's leading diversity officers, a review of the literature and the authors own experiences leading diversity change initiatives in higher education. The…

  11. Modelling consumer intakes of vegetable oils and fats.

    PubMed

    Tennant, David; Gosling, John Paul

    2015-01-01

    Vegetable oils and fats make up a significant part of the energy intake in typical European diets. However, their use as ingredients in a diverse range of different foods means that their consumption is often hidden, especially when oils and fats are used for cooking. As a result, there are no reliable estimates of the consumption of different vegetable oils and fats in the diet of European consumers for use in, for example, nutritional assessments or chemical risk assessments. We have developed an innovative model to estimate the consumption of vegetable oils and fats by European Union consumers using the European Union consumption databases and elements of probabilistic modelling. A key feature of the approach is the assessment of uncertainty in the modelling assumptions that can be used to build user confidence and to guide future development.

  12. Modelling consumer intakes of vegetable oils and fats

    PubMed Central

    Tennant, David; Gosling, John Paul

    2015-01-01

    Vegetable oils and fats make up a significant part of the energy intake in typical European diets. However, their use as ingredients in a diverse range of different foods means that their consumption is often hidden, especially when oils and fats are used for cooking. As a result, there are no reliable estimates of the consumption of different vegetable oils and fats in the diet of European consumers for use in, for example, nutritional assessments or chemical risk assessments. We have developed an innovative model to estimate the consumption of vegetable oils and fats by European Union consumers using the European Union consumption databases and elements of probabilistic modelling. A key feature of the approach is the assessment of uncertainty in the modelling assumptions that can be used to build user confidence and to guide future development. PMID:26160467

  13. Vegetation disturbance and maintenance of diversity in intermittently flooded Carolina Bays in South Carolina

    SciTech Connect

    Kirkman, L.K.; Sharitz, R.R. )

    1994-02-01

    The authors manipulated the fire regime and soil disturbance in four grass-dominated Carolina bay wetlands during a prolonged drought period and examined vegetation composition and cover within dominant vegetation types prior to and after treatments. The authors used the seedling emergence technique to determine the role of the seed bank in the recovery process. Burning did not affect richness, evenness, or diversity (all vegetation types combined); however, soil tillage increased diversity, including both evenness and richness. Percent similarity of the vegetation before and after disturbance was greater in the burning treatment than in the tillage treatment, probably due to greater disruption of the rhizomes of the perennial vegetation by tillage. Vegetation types varied in degree of recovery, although dominance was not altered by either treatment. Several native fugitive species increased following disturbance, indicating that species coexistence in these Carolina bay wetlands depends on the life history characteristics of residual vegetation, as well as that of seed bank species.

  14. Vegetation pattern formation of a water-biomass model

    NASA Astrophysics Data System (ADS)

    Wang, Xiaoli; Wang, Wendi; Zhang, Guohong

    2017-01-01

    In this paper, a mathematical model with diffusion and cross-diffusion is proposed to describe the interaction between the vegetation and the soil water. Based on the view of Turing pattern, we discuss the conditions of the diffusion-induced instability and the cross-diffusion-induced instability of a homogenous uniform steady state. We find that either a fast diffusion speed of water or a great hydraulic diffusivity due to the suction of roots may drive the instability of the homogenous steady state. Furthermore, we find that both the rain-fall rate and the infiltration feedback parameter can induce the transitions among the vegetation state, pattern formation and bare soil state. It is also found that the "terrain slope" may cause the instability of the homogenous steady state and drive the formation of periodic stripe pattern. Consequently, the diversity of dryland vegetation in reality can be explained as a result of pattern solutions of the model.

  15. 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

  16. Modelling of backscatter from vegetation layers

    NASA Technical Reports Server (NTRS)

    Van Zyl, J. J.; Engheta, N.; Papas, C. H.; Elachi, C.; Zebker, H.

    1985-01-01

    A simple way to build up a library of models which may be used to distinguish between the different types of vegetation and ground surfaces by means of their backscatter properties is presented. The curve of constant power received by the antenna (Gamma sphere) is calculated for the given Stokes Scattering Operator, and model parameters are adopted of the most similar library model Gamma sphere. Results calculated for a single scattering model resembling coniferous trees are compared with the Gamma spheres of a model resembling tropical region trees. The polarization which would minimize the effect of either the ground surface or the vegetation layer can be calculated and used to analyze the backscatter from the ground surface/vegetation layer combination, and enhance the power received from the desired part of the combination.

  17. Patterns of seed bank and vegetation diversity along a tidal freshwater river.

    PubMed

    Elsey-Quirk, Tracy; Leck, Mary Allessio

    2015-12-01

    Species richness and diversity may increase with spatial scale related to increased area and heterogeneity of habitat. Yet, in bidirectional hydrologically connected tidal ecosystems, secondary dispersal via hydrochory has the potential to homogenize seed banks, and both life history characteristics and tolerances to environmental conditions influence the composition of plant communities. How species richness, diversity, and composition of seed banks and vegetation change along environmental gradients and at different spatial scales is not well understood. We explored the relationships of seed bank and vegetation diversity across 135 plots along a tidal freshwater river in the Delaware Estuary, USA. Species richness and diversity were partitioned across three hierarchical spatial scales: individual plots, transects perpendicular to the tidal channel, and river kilometers. Community structure was also examined as it related to distance from the tidal channel and location along the tidal river. Species richness was 89 in the seed bank and 54 in the vegetation. Species-area relationships revealed that species richness reached a near maximum asymptote inland (20 m from channel) for the seed bank and at the edge (0 m) for the vegetation. Rare occurrences of species in the seed bank and vegetation were greatest 5 m from the channel edge. As spatial scale increased, seed bank richness increased, associated with the progressive accumulation of species. Seed bank diversity, however, was maximized within small plot areas and along the river. Diversity of the vegetation was maximized locally due to the abundance of a few common species. These findings suggest that suites of common species contributed to high localized vegetation diversity, yet large spatial scales maximized the number and diversity of species in the seed bank and vegetation through rare encounters, as well as the complexity of the landscape. © 2015 Botanical Society of America.

  18. A model of goal directed vegetable parenting practices.

    PubMed

    Hingle, Melanie; Beltran, Alicia; O'Connor, Teresia; Thompson, Deborah; Baranowski, Janice; Baranowski, Tom

    2012-04-01

    The aim of this study was to explore factors underlying parents' motivations to use vegetable parenting practices (VPP) using the Model of Goal Directed Vegetable Parenting Practices (MGDVPP) (an adaptation of the Model of Goal Directed Behavior) as the theoretical basis for qualitative interviews. In-depth interviews with parents of 3-5-year-old children were conducted over the telephone by trained interviewers following a script. MGDVPP constructs provided the theoretical framework guiding script development. Audio-recordings were transcribed and analyzed, with themes coded independently by two interviewers. Fifteen participants completed the study. Interviews elicited information about possible predictors of motivations as they related to VPP, and themes emerged related to each of the MGDVPP constructs (attitudes, positive anticipated emotions, negative anticipated emotions, subjective norms, and perceived behavioral control). Parents believed child vegetable consumption was important and associated with child health and vitality. Parents described motivations to engage in specific VPP in terms of emotional responses, influential relationships, food preferences, resources, and food preparation skills. Parents discussed specific strategies to encourage child vegetable intake. Interview data suggested parents used diverse VPP to encourage child intake and that varied factors predicted their use. Understanding these factors could inform the design of interventions to increase parents' use of parenting practices that promote long-term child consumption of vegetables.

  19. Evaluating models of climate and forest vegetation

    NASA Technical Reports Server (NTRS)

    Clark, James S.

    1992-01-01

    Understanding how the biosphere may respond to increasing trace gas concentrations in the atmosphere requires models that contain vegetation responses to regional climate. Most of the processes ecologists study in forests, including trophic interactions, nutrient cycling, and disturbance regimes, and vital components of the world economy, such as forest products and agriculture, will be influenced in potentially unexpected ways by changing climate. These vegetation changes affect climate in the following ways: changing C, N, and S pools; trace gases; albedo; and water balance. The complexity of the indirect interactions among variables that depend on climate, together with the range of different space/time scales that best describe these processes, make the problems of modeling and prediction enormously difficult. These problems of predicting vegetation response to climate warming and potential ways of testing model predictions are the subjects of this chapter.

  20. Branching model for vegetation. [polarimetric remote sensing

    NASA Technical Reports Server (NTRS)

    Yueh, Simon H.; Kong, J. A.; Jao, Jen K.; Shin, Robert T.; Le Toan, Thuy

    1992-01-01

    In the present branching model for remote sensing of vegetation, the frequency and angular responses of a two-scale cylinder cluster are calculated to illustrate the importance of vegetation architecture. Attention is given to the implementation of a two-scale branching model for soybeans, where the relative location of soybean plants is described by a pair of distribution functions. Theoretical backscattering coefficients evaluated by means of hole-correction pair distribution are in agreement with extensive data collected from soybean fields. The hole-correction approximation is found to be the more realistic.

  1. Effects of kangaroo rat exclusion on vegetation structure and plant species diversity in the Chihuahuan Desert.

    PubMed

    Heske, Edward J; Brown, James H; Guo, Qinfeng

    1993-10-01

    Long-term (1977-90) experimental exclusion of three species of kangaroo rats from study plots in the Chihuahuan Desert resulted in significant increases in abundance of a tall annual grass (Aristida adscensionis) and a perennial bunch grass (Eragrostis lehmanniana). This change in the vegetative cover affected use of these plots by several other rodent species and by foraging birds. The mechanism producing this change probably involves a combination of decreased soil disturbance and reduced predation on large-sized seeds when kangaroo rats are absent. Species diversity of summer annual dicots was greater on plots where kangaroo rats were present, as predicted by keystone predator models. However, it is not clear whether this was caused directly by activities of the kangaroo rats or indirectly as a consequence of the increase in grass cover. No experimental effect on species diversity of winter annual dicots was detected. Our study site was located in a natural transition between desert scrub and grassland, where abiotic conditions and the effects of organisms may be particularly influential in determining the structure and composition of vegetation. Under these conditions kangaroo rats have a dramatic effect on plant cover and species composition.

  2. An assessment of the impact of water impoundment and diversion structures on vegetation in Southern Arizona

    NASA Technical Reports Server (NTRS)

    Conn, J. S.; Mouat, D. A.; Clark, R. B.

    1975-01-01

    High-altitude color infrared photography was used to survey existing conditions, both upstream and downstream, from nineteen diversion structures in Southern Arizona to determine their effect upon vegetation health, vigor, and cover. A diversion structure is defined as a man/made feature constructed to control storm runoff. The results are used to determine the policy for future structure design.

  3. [Diversity and stability of arthropod community in peach orchard under effects of ground cover vegetation].

    PubMed

    Jiang, Jie-xian; Wan, Nian-feng; Ji, Xiang-yun; Dan, Jia-gui

    2011-09-01

    A comparative study was conducted on the arthropod community in peach orchards with and without ground cover vegetation. In the orchard with ground cover vegetation, the individuals of beneficial, neutral, and phytophagous arthropods were 1.48, 1.84 and 0.64 times of those in the orchard without ground cover vegetation, respectively, but the total number of arthropods had no significant difference with that in the orchard without ground cover vegetation. The species richness, Shannon's diversity, and Pielou's evenness index of the arthropods in the orchard with ground cover vegetation were 83.733 +/- 4.932, 4.966 +/- 0.110, and 0.795 +/- 0.014, respectively, being significantly higher than those in the orchard without ground cover vegetation, whereas the Berger-Parker's dominance index was 0.135 +/- 0.012, being significantly lower than that (0.184 +/- 0.018) in the orchard without ground cover vegetation. There were no significant differences in the stability indices S/N and Sd/Sp between the two orchards, but the Nn/Np, Nd/Np, and Sn/Sp in the orchard with ground cover vegetation were 0.883 +/- 0.123. 1714 +/- 0.683, and 0.781 +/- 0.040, respectively, being significantly higher than those in the orchard without ground cover vegetation. Pearson's correlation analysis indicated that in the orchard with ground cover vegetation, the Shannon's diversity index was significantly negatively correlated with Nd/Np, Sd/Sp, and S/N but had no significant correlations with Nn/Np and Sn/Sp, whereas in the orchard without ground cover vegetation, the diversity index was significantly positively correlated with Nn/Np and Nd/Np and had no significant correlations with Sd/Sp, Sn/Sp, and S/N.

  4. Submersed Aquatic Vegetation Modeling Output Online

    USGS Publications Warehouse

    Yin, Yao; Rogala, Jim; Sullivan, John; Rohweder, Jason J.

    2005-01-01

    Introduction The ability to predict the distribution of submersed aquatic vegetation in the Upper Mississippi River on the basis of physical or chemical variables is useful to resource managers. Wildlife managers have a keen interest in advanced estimates of food quantity such as American wildcelery (Vallisneria americana) population status to give out more informed advisories to hunters before the fall hunting season. Predictions for distribution of submerged aquatic vegetation beds can potentially increase hunter observance of voluntary avoidance zones where foraging birds are left alone to feed undisturbed. In years when submersed aquatic vegetation is predicted to be scarce in important wildlife habitats, managers can get the message out to hunters well before the hunting season (Jim Nissen, Upper Mississippi River National Wildlife and Fish Refuge, La Crosse District Manager, La Crosse, Wisconsin, personal communication). We developed a statistical model to predict the probability of occurrence of submersed aquatic vegetation in Pool 8 of the Upper Mississippi River on the basis of a few hydrological, physical, and geomorphic variables. Our model takes into consideration flow velocity, wind fetch, bathymetry, growing-season daily water level, and light extinction coefficient in the river (fig. 1) and calculates the probability of submersed aquatic vegetation existence in Pool 8 in individual 5- x 5-m grid cells. The model was calibrated using the data collected in 1998 (516 sites), 1999 (595 sites), and 2000 (649 sites) using a stratified random sampling protocol (Yin and others, 2000b). To validate the model, we chose the data from the Long Term Resource Monitoring Program (LTRMP) transect sampling in backwater areas (Rogers and Owens 1995; Yin and others, 2000a) and ran the model for each 5- x 5-m grid cell in every growing season from 1991 to 2001. We tallied all the cells and came up with an annual average percent frequency of submersed aquatic vegetation

  5. Modelling post-fire vegetation recovery in Portugal

    NASA Astrophysics Data System (ADS)

    Bastos, A.; Gouveia, C.; Dacamara, C. C.; Trigo, R. M.

    2011-05-01

    Wildfires in Mediterranean Europe have been increasing in number and extension over the last decades and constitute one of the major disturbances of these ecosystems. Portugal is the country with more burnt area in the last decade and the years of 2003 and 2005 were particularly devastating, the total burned areas of 425 000 and 338 000 ha being several times higher than the corresponding average. The year of 2005 further coincided with one of the most severe droughts since early 20th century. Due to different responses of vegetation to diverse fire regimes and to the complexity of landscape structures, fires have complex effects on vegetation recovery. Remote sensing has revealed to be a powerful tool in studying vegetation dynamics and in monitoring post-fire vegetation recovery, which is crucial to land-management and to prevent erosion. The main goals of the present work are (i) to assess the accuracy of a vegetation recovery model previously developed by the authors; (ii) to assess the model's performance, namely its sensitivity to initial conditions, to the temporal length of the input dataset and to missing data; (iii) to study vegetation recovery over two selected areas that were affected by two large wildfire events in the fire seasons of 2003 and 2005, respectively. The study relies on monthly values of NDVI over 11 yr (1998-2009), at 1 × 1 km spatial resolution, as obtained by the VEGETATION instrument. According to results from sensitivity analysis, the model is robust and able to provide good estimations of recovery times of vegetation when the regeneration process is regular, even when missing data is present. In what respect to the two selected burnt scars, results indicate that fire damage is a determinant factor of regeneration, as less damaged vegetation recovers more rapidly, which is mainly justified by the high coverage of Pinus Pinaster over the area, and by the fact that coniferous forests tend to recover slower than transitional woodland

  6. Modelling post-fire vegetation recovery in Portugal

    NASA Astrophysics Data System (ADS)

    Bastos, A.; Gouveia, C. M.; Dacamara, C. C.; Trigo, R. M.

    2011-12-01

    Wildfires in Mediterranean Europe have been increasing in number and extension over the last decades and constitute one of the major disturbances of these ecosystems. Portugal is the country with more burnt area in the last decade and the years of 2003 and 2005 were particularly devastating, the total burned areas of 425 000 and 338 000 ha being several times higher than the corresponding average. The year of 2005 further coincided with one of the most severe droughts since early 20th century. Due to different responses of vegetation to diverse fire regimes and to the complexity of landscape structures, fires have complex effects on vegetation recovery. Remote sensing has revealed to be a powerful tool in studying vegetation dynamics and in monitoring post-fire vegetation recovery, which is crucial to land-management and to prevent erosion. The main goals of the present work are (i) to assess the accuracy of a vegetation recovery model previously developed by the authors; (ii) to assess the model's performance, namely its sensitivity to initial conditions, to the temporal length of the input dataset and to missing data; (iii) to study vegetation recovery over two selected areas that were affected by two large wildfire events in the fire seasons of 2003 and 2005, respectively. The study relies on monthly values of NDVI over 11 years (1998-2009), at 1 km × 1 km spatial resolution, as obtained by the VEGETATION instrument. According to results from sensitivity analysis, the model is robust and able to provide good estimations of recovery times of vegetation when the regeneration process is regular, even when missing data is present. In respect to the two selected burnt scars, results indicate that fire damage is a determinant factor of regeneration, as less damaged vegetation recovers more rapidly, which is mainly justified by the high coverage of Pinus pinaster over the area, and by the fact that coniferous forests tend to recover slower than transitional woodland

  7. 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.

  8. Disentangling vegetation diversity from climate-energy and habitat heterogeneity for explaining animal geographic patterns.

    PubMed

    Jiménez-Alfaro, Borja; Chytrý, Milan; Mucina, Ladislav; Grace, James B; Rejmánek, Marcel

    2016-03-01

    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.

  9. 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.

  10. Anticipating the spatio-temporal response of plant diversity and vegetation structure to climate and land use change in a protected area.

    PubMed

    Boulangeat, Isabelle; Georges, Damien; Dentant, Cédric; Bonet, Richard; Van Es, Jérémie; Abdulhak, Sylvain; Zimmermann, Niklaus E; Thuiller, Wilfried

    2014-12-01

    Vegetation is a key driver of ecosystem functioning (e.g. productivity and stability) and of the maintenance of biodiversity (e.g. creating habitats for other species groups). While vegetation sensitivity to climate change has been widely investgated, its spatio-temporally response to the dual efects of land management and climate change has been ignored at landscape scale. Here we use a dynamic vegetation model called FATE-HD, which describes the dominant vegetation dynamics and associated functional diversity, in order to anticipate vegetation response to climate and land-use changes in both short and long-term perspectives. Using three contrasted management scenarios for the Ecrins National Park (French Alps) developed in collaboration with the park managers, and one regional climate change scenario, we tracked the dynamics of vegetation structure (forest expansion) and functional diversity over 100 years of climate change and a further 400 additional years of stabilization. As expected, we observed a slow upward shift in forest cover distribution, which appears to be severely impacted by pasture management (i.e. maintenance or abandonment). The tme lag before observing changes in vegetation cover was the result of demographic and seed dispersal processes. However, plant diversity response to environmental changes was rapid. Afer land abandonment, local diversity increased and spatial turnover was reduced, whereas local diversity decreased following land use intensification. Interestingly, in the long term, as both climate and management scenarios interacted, the regional diversity declined. Our innovative spatio-temporally explicit framework demonstrates that the vegetation may have contrasting responses to changes in the short and the long term. Moreover, climate and land-abandonment interact extensively leading to a decrease in both regional diversity and turnover in the long term. Based on our simulations we therefore suggest a continuing moderate intensity

  11. Anticipating the spatio-temporal response of plant diversity and vegetation structure to climate and land use change in a protected area

    PubMed Central

    Boulangeat, Isabelle; Georges, Damien; Dentant, Cédric; Bonet, Richard; Van Es, Jérémie; Abdulhak, Sylvain; Zimmermann, Niklaus E.; Thuiller, Wilfried

    2014-01-01

    Vegetation is a key driver of ecosystem functioning (e.g. productivity and stability) and of the maintenance of biodiversity (e.g. creating habitats for other species groups). While vegetation sensitivity to climate change has been widely investgated, its spatio-temporally response to the dual efects of land management and climate change has been ignored at landscape scale. Here we use a dynamic vegetation model called FATE-HD, which describes the dominant vegetation dynamics and associated functional diversity, in order to anticipate vegetation response to climate and land-use changes in both short and long-term perspectives. Using three contrasted management scenarios for the Ecrins National Park (French Alps) developed in collaboration with the park managers, and one regional climate change scenario, we tracked the dynamics of vegetation structure (forest expansion) and functional diversity over 100 years of climate change and a further 400 additional years of stabilization. As expected, we observed a slow upward shift in forest cover distribution, which appears to be severely impacted by pasture management (i.e. maintenance or abandonment). The tme lag before observing changes in vegetation cover was the result of demographic and seed dispersal processes. However, plant diversity response to environmental changes was rapid. Afer land abandonment, local diversity increased and spatial turnover was reduced, whereas local diversity decreased following land use intensification. Interestingly, in the long term, as both climate and management scenarios interacted, the regional diversity declined. Our innovative spatio-temporally explicit framework demonstrates that the vegetation may have contrasting responses to changes in the short and the long term. Moreover, climate and land-abandonment interact extensively leading to a decrease in both regional diversity and turnover in the long term. Based on our simulations we therefore suggest a continuing moderate intensity

  12. Mathematical Modeling of Diverse Phenomena

    NASA Technical Reports Server (NTRS)

    Howard, J. C.

    1979-01-01

    Tensor calculus is applied to the formulation of mathematical models of diverse phenomena. Aeronautics, fluid dynamics, and cosmology are among the areas of application. The feasibility of combining tensor methods and computer capability to formulate problems is demonstrated. The techniques described are an attempt to simplify the formulation of mathematical models by reducing the modeling process to a series of routine operations, which can be performed either manually or by computer.

  13. Mathematical Modeling of Flow Through Vegetated Regions

    DTIC Science & Technology

    2013-08-01

    to model contaminants , nutrients, fish eggs, and several other things of environmental , ecological, and industrial importance. Besides vegetated...flow and transport through urban environments , forests, fields of crops, biofilm reactors, and porous media. 158 178 Bibliography [1] S. Al-Sadder and...interface methods, turbulent flows, fluid-structure interaction REPORT DOCUMENTATION PAGE 11. SPONSOR/MONITOR’S REPORT NUMBER(S) 10. SPONSOR/MONITOR’S

  14. Vegetation Water Content Mapping in a Diverse Agricultural Landscape: National Airborne Field Experiment 2006

    NASA Technical Reports Server (NTRS)

    Cosh, Michael H.; Jing Tao; Jackson, Thomas J.; McKee, Lynn; O'Neill, Peggy

    2011-01-01

    Mapping land cover and vegetation characteristics on a regional scale is critical to soil moisture retrieval using microwave remote sensing. In aircraft-based experiments such as the National Airborne Field Experiment 2006 (NAFE 06), it is challenging to provide accurate high resolution vegetation information, especially on a daily basis. A technique proposed in previous studies was adapted here to the heterogenous conditions encountered in NAFE 06, which included a hydrologically complex landscape consisting of both irrigated and dryland agriculture. Using field vegetation sampling and ground-based reflectance measurements, the knowledge base for relating the Normalized Difference Water Index (NDWI) and the vegetation water content was extended to a greater diversity of agricultural crops, which included dryland and irrigated wheat, alfalfa, and canola. Critical to the generation of vegetation water content maps, the land cover for this region was determined from satellite visible/infrared imagery and ground surveys with an accuracy of 95.5% and a kappa coefficient of 0.95. The vegetation water content was estimated with a root mean square error of 0.33 kg/sq m. The results of this investigation contribute to a more robust database of global vegetation water content observations and demonstrate that the approach can be applied with high accuracy. Keywords: Vegetation, field experimentation, thematic mapper, NDWI, agriculture.

  15. Vegetation Water Content Mapping in a Diverse Agricultural Landscape: National Airborne Field Experiment 2006

    NASA Technical Reports Server (NTRS)

    Cosh, Michael H.; Jing Tao; Jackson, Thomas J.; McKee, Lynn; O'Neill, Peggy

    2011-01-01

    Mapping land cover and vegetation characteristics on a regional scale is critical to soil moisture retrieval using microwave remote sensing. In aircraft-based experiments such as the National Airborne Field Experiment 2006 (NAFE 06), it is challenging to provide accurate high resolution vegetation information, especially on a daily basis. A technique proposed in previous studies was adapted here to the heterogenous conditions encountered in NAFE 06, which included a hydrologically complex landscape consisting of both irrigated and dryland agriculture. Using field vegetation sampling and ground-based reflectance measurements, the knowledge base for relating the Normalized Difference Water Index (NDWI) and the vegetation water content was extended to a greater diversity of agricultural crops, which included dryland and irrigated wheat, alfalfa, and canola. Critical to the generation of vegetation water content maps, the land cover for this region was determined from satellite visible/infrared imagery and ground surveys with an accuracy of 95.5% and a kappa coefficient of 0.95. The vegetation water content was estimated with a root mean square error of 0.33 kg/sq m. The results of this investigation contribute to a more robust database of global vegetation water content observations and demonstrate that the approach can be applied with high accuracy. Keywords: Vegetation, field experimentation, thematic mapper, NDWI, agriculture.

  16. Modeling gap probability in discontinuous vegetation canopies

    NASA Technical Reports Server (NTRS)

    Li, Xiaowen; Strahler, Alan H.

    1987-01-01

    In the present model for the gap probability of a discontinuous vegetation canopy, the assumption of a negative exponential attenuation within individual plant canopies will yield a problem involving the distribution distances within canopies through which a ray will pass. If, however, the canopies intersect and/or overlap, so that foliage density remains constant within the overlap area, the problem can be approached with two types of approximations. Attention is presently given to the case of a comparison of modeled gap probabilities with those observed for a stand of Maryland pine, which shows good agreement for zenith angles of illumination up to about 45 deg.

  17. Herbaceous versus forested riparian vegetation: narrow and simple versus wide, woody and diverse stream habitat

    Treesearch

    C.R. Jackson; D.S. Leigh; S.L. Scarbrough; J.F. Chamblee

    2014-01-01

    We investigated interactions of riparian vegetative conditions upon a suite of channel morphological variables: active channel width, variability of width within a reach, large wood frequency, mesoscale habitat distributions, mesoscale habitat diversity, median particle size and per cent fines. We surveyed 49 wadeable streams, 45 with low levels of development,...

  18. Sampling and estimation procedures for the vegetation diversity and structure indicator

    Treesearch

    Bethany K. Schulz; William A. Bechtold; Stanley J. Zarnoch

    2009-01-01

    The Vegetation Diversity and Structure Indicator (VEG) is an extensive inventory of vascular plants in the forests of the United States. The VEG indicator provides baseline data to assess trends in forest vascular plant species richness and composition, and the relative abundance and spatial distribution of those species, including invasive and introduced species. The...

  19. Effects of riparian zone buffer widths on vegetation diversity in southern Appalachian headwater catchments

    Treesearch

    Katherine J. Elliott; James M. Vose

    2016-01-01

    In mountainous areas such as the southern Appalachians USA, riparian zones are difficult to define. Vegetation is a commonly used riparian indicator and plays a key role in protecting water resources, but adequate knowledge of floristic responses to riparian disturbances is lacking. Our objective was to quantify changes in stand-level floristic diversity of...

  20. Vegetation water content mapping in a diverse agricultural landscape: National Airborne Field Experiment 2006

    NASA Astrophysics Data System (ADS)

    Cosh, Michael H.; Tao, Jing; Jackson, Thomas J.; McKee, Lynn; O'Neill, Peggy

    2010-05-01

    Mapping land cover and vegetation characteristics on a regional scale is critical to soil moisture retrieval using microwave remote sensing. In aircraft-based experiments such as the National Airborne Field Experiment 2006 (NAFE'06), it is challenging to provide accurate high resolution vegetation information, especially on a daily basis. A technique proposed in previous studies was adapted here to the heterogenous conditions encountered in NAFE'06, which included a hydrologically complex landscape consisting of both irrigated and dryland agriculture. Using field vegetation sampling and ground-based reflectance measurements, the knowledge base for relating the Normalized Difference Water Index (NDWI) and the vegetation water content was extended to a greater diversity of agricultural crops, which included dryland and irrigated wheat, alfalfa, and canola. Critical to the generation of vegetation water content maps, the land cover for this region was determined from satellite visible/infrared imagery and ground surveys with an accuracy of 95.5% and a kappa coefficient of 0.95. The vegetation water content was estimated with a root mean square error of 0.33 kg/m2. The results of this investigation contribute to a more robust database of global vegetation water content observations and demonstrate that the approach can be applied with high accuracy.

  1. Introducing tropical lianas in a vegetation model

    NASA Astrophysics Data System (ADS)

    Verbeeck, Hans; De Deurwaerder, Hannes; Brugnera, Manfredo di Procia e.; Krshna Moorthy Paravathi, Sruthi; Pausenberger, Nancy; Roels, Jana; kearsley, elizabeth

    2016-04-01

    Tropical forests are essential components of the earth system and play a critical role for land surface feedbacks to climate change. These forests are currently experiencing large-scale structural changes, including the increase of liana abundance and biomass. This liana proliferation might have large impacts on the carbon cycle of tropical forests. However no single global vegetation model currently accounts for lianas. The TREECLIMBERS project (ERC starting grant) aims to introduce for the first time lianas into a vegetation model. The project attempts to reach this challenging goal by performing a global meta-analysis on liana data and by collecting new data in South American forests. Those new and existing datasets form the basis of a new liana plant functional type (PFT) that will be included in the Ecosystem Demography model (ED2). This presentation will show an overview of the current progress of the TREECLIMBERS project. Liana inventory data collected in French Guiana along a forest disturbance gradient show the relation between liana abundance and disturbance. Xylem water isotope analysis indicates that trees and lianas can rely on different soil water resources. New modelling concepts for liana PFTs will be presented and in-situ leaf gas exchange and sap flow data are used to parameterize water and carbon fluxes for this new PFT. Finally ongoing terrestrial LiDAR observations of liana infested forest will be highlighted.

  2. Probabilistic Evaluation of Anthropogenic Regulations In a Vegetated River Channel Using a Vegetation Dynamics Modeling

    NASA Astrophysics Data System (ADS)

    Miyamoto, Hitoshi

    2015-04-01

    Vegetation overgrowth in fluvial floodplains, gravel beds, and sand bars has been a serious engineering problem for riparian management in Japan. From the viewpoints of flood control and ecological conservation, it would be necessary to predict the vegetation dynamics accurately for long-term duration. In this research, we have developed a stochastic model for predicting the vegetation dynamics in fluvial floodplains with emphasis on the interaction with flood impacts. The model consists of the following four components: (i) long-term stochastic behavior of flow discharge, (ii) hydrodynamics in a channel with floodplain vegetation, (iii) variation of riverbed topography, and (iv) vegetation dynamics on floodplains. In the vegetation dynamics model, the flood discharge (i) is stochastically simulated using a filtered Poisson process, one of the conventional approaches in hydrological time-series generation. The component for vegetation dynamics (iv) includes the effects of tree growth, mortality by floods, and infant tree recruitment. Vegetation condition has been observed mainly before and after floods since 2008 at a field site located between 23-24 km from the river mouth in Kako River, Japan. The Kako River has the catchment area of 1,730 km2 and the main channel length of 96 km. This site is one of the vegetation overgrowth sites in the Kako River floodplains. The predominant tree species are willows and bamboos. In the field survey, the position, trunk diameter and height of each tree as well as the riverbed materials were measured after several flood events to investigate their impacts on the floodplain vegetation community. This presentation tries to examine effects of anthropogenic river regulations, i.e., thinning and cutting-down, in the vegetated channel in Kako River by using the vegetation dynamics model. Sensitivity of both the flood water level and the vegetation status in the channel is statistically evaluated in terms of the different cutting

  3. Canopy reflectance modelling of semiarid vegetation

    NASA Technical Reports Server (NTRS)

    Franklin, Janet

    1994-01-01

    Three different types of remote sensing algorithms for estimating vegetation amount and other land surface biophysical parameters were tested for semiarid environments. These included statistical linear models, the Li-Strahler geometric-optical canopy model, and linear spectral mixture analysis. The two study areas were the National Science Foundation's Jornada Long Term Ecological Research site near Las Cruces, NM, in the northern Chihuahuan desert, and the HAPEX-Sahel site near Niamey, Niger, in West Africa, comprising semiarid rangeland and subtropical crop land. The statistical approach (simple and multiple regression) resulted in high correlations between SPOT satellite spectral reflectance and shrub and grass cover, although these correlations varied with the spatial scale of aggregation of the measurements. The Li-Strahler model produced estimated of shrub size and density for both study sites with large standard errors. In the Jornada, the estimates were accurate enough to be useful for characterizing structural differences among three shrub strata. In Niger, the range of shrub cover and size in short-fallow shrublands is so low that the necessity of spatially distributed estimation of shrub size and density is questionable. Spectral mixture analysis of multiscale, multitemporal, multispectral radiometer data and imagery for Niger showed a positive relationship between fractions of spectral endmembers and surface parameters of interest including soil cover, vegetation cover, and leaf area index.

  4. A nonlinear coupled soil moisture-vegetation model

    NASA Astrophysics Data System (ADS)

    Liu, Shikuo; Liu, Shida; Fu, Zuntao; Sun, Lan

    2005-06-01

    Based on the physical analysis that the soil moisture and vegetation depend mainly on the precipitation and evaporation as well as the growth, decay and consumption of vegetation a nonlinear dynamic coupled system of soil moisture-vegetation is established. Using this model, the stabilities of the steady states of vegetation are analyzed. This paper focuses on the research of the vegetation catastrophe point which represents the transition between aridness and wetness to a great extent. It is shown that the catastrophe point of steady states of vegetation depends mainly on the rainfall P and saturation value v0, which is selected to balance the growth and decay of vegetation. In addition, when the consumption of vegetation remains constant, the analytic solution of the vegetation equation is obtained.

  5. Discrete Random Media Techniques for Microwave Modeling of Vegetated Terrain

    NASA Technical Reports Server (NTRS)

    Lang, R. H.

    1984-01-01

    Microwave modeling of vegetated terrain was investigated. The purpose was to: (1) use discrete scatter theory to model vegetation (crops and forested regions) in microwave region; (2) develop models for scatterers and ground; (3) multiple scattering analysis relate model parameters to average scattered power; and (4) develop inversion techniques to remotely determine model parameters.

  6. Diversity in plant hydraulic traits explains seasonal and inter-annual variations of vegetation dynamics in seasonally dry tropical forests.

    PubMed

    Xu, Xiangtao; Medvigy, David; Powers, Jennifer S; Becknell, Justin M; Guan, Kaiyu

    2016-10-01

    We assessed whether diversity in plant hydraulic traits can explain the observed diversity in plant responses to water stress in seasonally dry tropical forests (SDTFs). The Ecosystem Demography model 2 (ED2) was updated with a trait-driven mechanistic plant hydraulic module, as well as novel drought-phenology and plant water stress schemes. Four plant functional types were parameterized on the basis of meta-analysis of plant hydraulic traits. Simulations from both the original and the updated ED2 were evaluated against 5 yr of field data from a Costa Rican SDTF site and remote-sensing data over Central America. The updated model generated realistic plant hydraulic dynamics, such as leaf water potential and stem sap flow. Compared with the original ED2, predictions from our novel trait-driven model matched better with observed growth, phenology and their variations among functional groups. Most notably, the original ED2 produced unrealistically small leaf area index (LAI) and underestimated cumulative leaf litter. Both of these biases were corrected by the updated model. The updated model was also better able to simulate spatial patterns of LAI dynamics in Central America. Plant hydraulic traits are intercorrelated in SDTFs. Mechanistic incorporation of plant hydraulic traits is necessary for the simulation of spatiotemporal patterns of vegetation dynamics in SDTFs in vegetation models. © 2016 The Authors. New Phytologist © 2016 New Phytologist Trust.

  7. A microwave scattering model for layered vegetation

    NASA Technical Reports Server (NTRS)

    Karam, Mostafa A.; Fung, Adrian K.; Lang, Roger H.; Chauhan, Narinder S.

    1992-01-01

    A microwave scattering model was developed for layered vegetation based on an iterative solution of the radiative transfer equation up to the second order to account for multiple scattering within the canopy and between the ground and the canopy. The model is designed to operate over a wide frequency range for both deciduous and coniferous forest and to account for the branch size distribution, leaf orientation distribution, and branch orientation distribution for each size. The canopy is modeled as a two-layered medium above a rough interface. The upper layer is the crown containing leaves, stems, and branches. The lower layer is the trunk region modeled as randomly positioned cylinders with a preferred orientation distribution above an irregular soil surface. Comparisons of this model with measurements from deciduous and coniferous forests show good agreements at several frequencies for both like and cross polarizations. Major features of the model needed to realize the agreement include allowance for: (1) branch size distribution, (2) second-order effects, and (3) tree component models valid over a wide range of frequencies.

  8. Ant diversity in Brazilian tropical dry forests across multiple vegetation domains

    NASA Astrophysics Data System (ADS)

    Figueiredo Silva, Luciana; Mello Souza, Rayana; Solar, Ricardo R. C.; de Siqueira Neves, Frederico

    2017-03-01

    Understanding the environmental drivers of biodiversity persistence and community organization in natural ecosystems is of great importance for planning the conservation of those ecosystems. This comprehension is even more important in severely threatened ecosystems. In this context, we analyzed ant communities in tropical dry forests (TDFs) in Brazil. These forests are embedded within other biomes, such as Cerrado and Caatinga. In this study, we asked whether (i) ant species richness and composition changes between TDFs within different vegetation domains; (ii) whether ant species richness and β-diversity increase north-to-south, possibly related to changes in tree richness and tree density; and (iii) species replacement contributes relatively more to β-diversity than does nestedness. We found that species composition is unique to each TDF within different biomes, and that species richness and β-diversity differ among the vegetation domains, being smaller in the Caatinga. We also found that replacement contributes most to β-diversity, although this contribution is lower in Caatinga than in Cerrado. We show that regional context is the main driver of species diversity, which is likely to be driven by both historical and ecological mechanisms. By analyzing large spatial scale variation in TDF environmental characteristics, we were able to evaluate how ant diversity changes along an environmental gradient. The high levels of species replacement and unique species composition of each region indicates that, to fully conserve TDFs, we need to have various conservation areas distributed across the entire range of vegetation domains in which these forests can be found. Thus, we demonstrate that a landscape-wise planning is urgent and necessary in order to preserve tropical dry forests.

  9. Functional diversity, succession, and human-mediated disturbances in raised bog vegetation.

    PubMed

    Dyderski, Marcin K; Czapiewska, Natalia; Zajdler, Mateusz; Tyborski, Jarosław; Jagodziński, Andrzej M

    2016-08-15

    Raised and transitional bogs are one of the most threatened types of ecosystem, due to high specialisation of biota, associated with adaptations to severe environmental conditions. The aim of the study was to characterize the relationships between functional diversity (reflecting ecosystem-shaping processes) of raised bog plant communities and successional gradients (expressed as tree dimensions) and to show how impacts of former clear cuts may alter these relationships in two raised bogs in 'Bory Tucholskie' National Park (N Poland). Herbaceous layers of the plant communities were examined by floristic relevés (25m(2)) on systematically established transects. We also assessed patterns of tree ring widths. There were no relationships between vegetation functional diversity components and successional progress: only functional dispersion was negatively, but weakly, correlated with median DBH. Lack of these relationships may be connected with lack of prevalence of habitat filtering and low level of competition over all the successional phases. Former clear cuts, indicated by peaks of tree ring width, influenced the growth of trees in the bogs studied. In the bog with more intensive clear cuts we found more species with higher trophic requirements, which may indicate nutrient influx. However, we did not observe differences in vegetation patterns, functional traits or functional diversity indices between the two bogs studied. We also did not find an influence of clear cut intensity on relationships between functional diversity indices and successional progress. Thus, we found that alteration of the ecosystems studied by neighbourhood clear cuts did not affect the bogs strongly, as the vegetation was resilient to these impacts. Knowledge of vegetation resilience after clear cuts may be crucial for conservation planning in raised bog ecosystems.

  10. Vegetable parenting practices scale. Item response modeling analyses.

    PubMed

    Chen, Tzu-An; O'Connor, Teresia M; Hughes, Sheryl O; Beltran, Alicia; Baranowski, Janice; Diep, Cassandra; Baranowski, Tom

    2015-08-01

    To evaluate the psychometric properties of a vegetable parenting practices scale using multidimensional polytomous item response modeling which enables assessing item fit to latent variables and the distributional characteristics of the items in comparison to the respondents. We also tested for differences in the ways item function (called differential item functioning) across child's gender, ethnicity, age, and household income groups. Parents of 3-5 year old children completed a self-reported vegetable parenting practices scale online. Vegetable parenting practices consisted of 14 effective vegetable parenting practices and 12 ineffective vegetable parenting practices items, each with three subscales (responsiveness, structure, and control). Multidimensional polytomous item response modeling was conducted separately on effective vegetable parenting practices and ineffective vegetable parenting practices. One effective vegetable parenting practice item did not fit the model well in the full sample or across demographic groups, and another was a misfit in differential item functioning analyses across child's gender. Significant differential item functioning was detected across children's age and ethnicity groups, and more among effective vegetable parenting practices than ineffective vegetable parenting practices items. Wright maps showed items only covered parts of the latent trait distribution. The harder- and easier-to-respond ends of the construct were not covered by items for effective vegetable parenting practices and ineffective vegetable parenting practices, respectively. Several effective vegetable parenting practices and ineffective vegetable parenting practices scale items functioned differently on the basis of child's demographic characteristics; therefore, researchers should use these vegetable parenting practices scales with caution. Item response modeling should be incorporated in analyses of parenting practice questionnaires to better assess

  11. Vegetable parenting practices scale. Item response modeling analyses

    PubMed Central

    Chen, Tzu-An; O’Connor, Teresia; Hughes, Sheryl; Beltran, Alicia; Baranowski, Janice; Diep, Cassandra; Baranowski, Tom

    2015-01-01

    Objective To evaluate the psychometric properties of a vegetable parenting practices scale using multidimensional polytomous item response modeling which enables assessing item fit to latent variables and the distributional characteristics of the items in comparison to the respondents. We also tested for differences in the ways item function (called differential item functioning) across child’s gender, ethnicity, age, and household income groups. Method Parents of 3–5 year old children completed a self-reported vegetable parenting practices scale online. Vegetable parenting practices consisted of 14 effective vegetable parenting practices and 12 ineffective vegetable parenting practices items, each with three subscales (responsiveness, structure, and control). Multidimensional polytomous item response modeling was conducted separately on effective vegetable parenting practices and ineffective vegetable parenting practices. Results One effective vegetable parenting practice item did not fit the model well in the full sample or across demographic groups, and another was a misfit in differential item functioning analyses across child’s gender. Significant differential item functioning was detected across children’s age and ethnicity groups, and more among effective vegetable parenting practices than ineffective vegetable parenting practices items. Wright maps showed items only covered parts of the latent trait distribution. The harder- and easier-to-respond ends of the construct were not covered by items for effective vegetable parenting practices and ineffective vegetable parenting practices, respectively. Conclusions Several effective vegetable parenting practices and ineffective vegetable parenting practices scale items functioned differently on the basis of child’s demographic characteristics; therefore, researchers should use these vegetable parenting practices scales with caution. Item response modeling should be incorporated in analyses of parenting

  12. A Coupled Vegetation-Crust Model for Patchy Landscapes

    NASA Astrophysics Data System (ADS)

    Kinast, Shai; Ashkenazy, Yosef; Meron, Ehud

    2016-03-01

    A new model for patchy landscapes in drylands is introduced. The model captures the dynamics of biogenic soil crusts and their mutual interactions with vegetation growth. The model is used to identify spatially uniform and spatially periodic solutions that represent different vegetation-crust states, and map them along the rainfall gradient. The results are consistent extensions of the vegetation states found in earlier models. A significant difference between the current and earlier models of patchy landscapes is found in the bistability range of vegetated and unvegetated states; the incorporation of crust dynamics shifts the onset of vegetation patterns to a higher precipitation value and increases the biomass amplitude. These results can shed new light on the involvement of biogenic crusts in desertification processes that involve vegetation loss.

  13. Potential benefits of plant diversity on vegetated roofs: a literature review.

    PubMed

    Cook-Patton, Susan C; Bauerle, Taryn L

    2012-09-15

    Although vegetated green roofs can be difficult to establish and maintain, they are an increasingly popular method for mitigating the negative environmental impacts of urbanization. Most green roof development has focused on maximizing green roof performance by planting one or a few drought-tolerant species. We present an alternative approach, which recognizes green roofs as dynamic ecosystems and employs a diversity of species. We draw links between the ecological and green roof literature to generate testable predictions about how increasing plant diversity could improve short- and long-term green roof functioning. Although we found few papers that experimentally manipulated diversity on green roofs, those that did revealed ecological dynamics similar to those in more natural systems. However, there are many unresolved issues. To improve overall green roof performance, we should (1) elucidate the links among plant diversity, structural complexity, and green roof performance, (2) describe feedback mechanisms between plant and animal diversity on green roofs, (3) identify species with complementary traits, and (4) determine whether diverse green roof communities are more resilient to disturbance and environmental change than less diverse green roofs. Copyright © 2012 Elsevier Ltd. All rights reserved.

  14. Insect diversity in organic rice fields under two management systems of levees vegetation.

    PubMed

    Acosta, L G; Jahnke, S M; Redaelli, L R; Pires, P R S

    2017-11-01

    Simplified environments characterize agroecosystems, reducing the diversity of associated plants, which are not cultivated for economic purposes, causing unbalances that can promote the emergence of cultivated plants pests, as well as the reduction of their natural enemies. Management systems that increase diversity in agroecosystems can extend the action of natural enemies of pests. Studies to understand the diversity of insects associated with rice cultivation and determine their ecological guilds can provide information about the composition and structure of such ecosystems, which can be applied to integrated pest management. Therefore, the study aimed to describe and compare groups of insects in irrigated rice fields, with organic management using two different systems of levees vegetation management, and relate them to the phenological states of rice cultivation (seedling, vegetative, and reproductive). Samples were taken in a plantation located in Águas Claras district of Viamão, RS. The total area of 18 ha was divided into two. A subarea called not cut (NC), where wild vegetation of levees was maintained, and the subarea named cut (C), where monthly cuts were made to levees vegetation, from the beginning of soil preparation until the harvest. From October 2012 to March 2013 were held weekly collections in quadrats randomly located in both the rice fields and the levees. A total of 800 insects were collected, 429 in the C subarea and 371 in the NC. There were identified 97 morphospecies in the C and 108 in NC, being 54 shared between the subareas. The captured insects were grouped into guilds: saprophages (C = 38.2%; NC = 27.5%), phytophagous (C = 28.5%; NC = 33.2%), entomophagous (grouping parasitoids and predators) (C = 29.4%; NC = 35%) and finally other insects (C = 4 %; NC = 4.3%). The peak abundance of phytophagous and entomophagous was registered in the vegetative stage of rice. At the same stage the UPGMA analysis showed that similarity in species

  15. Multi-Scale Modeling of Wave Attenuation by Vegetation

    NASA Astrophysics Data System (ADS)

    Chen, Q. J.; Zhu, L.; Chakrabarti, A.

    2016-02-01

    In the past decade, interest in wave attenuation by vegetation has increased considerably as coastal scientists and engineers search for sustainable solutions to mitigate the impacts of climate change and natural hazards. It is well known that vegetation in wetlands can effectively reduce the flow speed, modify turbulence structure, attenuate wave energy, and affect sediment dynamics. Restoring coastal wetlands and reducing flood risks require improved understanding and better predictive capability of wave and surge attenuation over inundated coastal landscapes with vegetation. The interactions of surface weaves and natural vegetation span over a large range of scales, from turbulence and eddies at the vegetation stem scale to wave generation in vast inundated wetlands of hundreds of square miles under hurricane conditions. The study is focused on a phase-averaged energy-based model and phase-resolving Euler and Navier-Stokes (N-S) solvers with different representations of submerged vegetation. We will present recent advances in multi-scale modeling of wave attenuation by wetland vegetation. Numerical modeling results ranging from vegetation-resolved large eddy simulation under idealized conditions to incorporating vegetation-induced drag forces into conservation laws of momentum and energy for engineering applications will be shown. Effects of vegetation flexibility, turbulence closure, and various wave theories on the prediction of wave attenuation and the choice of vegetation drag coefficients will be discussed.

  16. Improving the Projections of Vegetation Biogeography by Integrating Climate Envelope Models and Dynamic Global Vegetation Models

    NASA Astrophysics Data System (ADS)

    Case, M. J.; Kim, J. B.

    2015-12-01

    Assessing changes in vegetation is increasingly important for conservation planning in the face of climate change. Dynamic global vegetation models (DGVMs) are important tools for assessing such changes. DGVMs have been applied at regional scales to create projections of range expansions and contractions of plant functional types. Many DGVMs use a number of algorithms to determine the biogeography of plant functional types. One such DGVM, MC2, uses a series of decision trees based on bioclimatic thresholds while others, such as LPJ, use constraining emergent properties with a limited set of bioclimatic threshold-based rules. Although both approaches have been used widely, we demonstrate that these biogeography outputs perform poorly at continental scales when compared to existing potential vegetation maps. Specifically, we found that with MC2, the algorithm for determining leaf physiognomy is too simplistic to capture arid and semi-arid vegetation in much of the western U.S., as well as is the algorithm for determining the broadleaf and needleleaf mix in the Southeast. With LPJ, we found that the bioclimatic thresholds used to allow seedling establishment are too broad and fail to capture regional-scale biogeography of the plant functional types. In response, we demonstrate a new approach to determining the biogeography of plant functional types by integrating the climatic thresholds produced for individual tree species by a series of climate envelope models with the biogeography algorithms of MC2 and LPJ. Using this approach, we find that MC2 and LPJ perform considerably better when compared to potential vegetation maps.

  17. A Comparison of Interactively Coupled Paleoclimate-Vegetation Models With the Vegetation Record

    NASA Astrophysics Data System (ADS)

    Batra, P.; Pollard, D.; Barron, E.

    2001-05-01

    Climate-vegetation interactions are a key ingredient in understanding Earth system history. Vegetation models used to explore past climate and past vegetation distributions are largely based on modern plant-climate relationships. This study explores the application of four such models, each built upon different assumptions and parameters, and determines how well each model reproduces past records. In addition, this approach enables an exploration of the potential influence of vegetation on paleoclimates. The four vegetation models (the BIOME 3.5 model of Haxeltine and Prentice (1996), the simple dynamic vegetation model of Cosgrove (1998), the EVE model of Bergengren et al. (2001) and the IBIS model of Foley et al. (1996)) were run interactively with a general circulation model (GCM) of the atmosphere for four time periods. The GCM utilized is GENESIS 2.0, designed for paleoclimate studies. The four time periods for which all four vegetation models are employed are the Early Miocene, Oxygen Isotope Stage Three (warm and cool phases) between 30,000 and 42,000 years ago, and the Last Glacial Maximum. Differences between parameterizations include differences in the number of vegetation types in each model, the inclusion in some models of the influence of atmospheric CO2 levels on the growth of C3 versus C4 vegetation and on stomatal conductance, and whether the models focus on the equilibrium or dynamic state of ecosystems. Preliminary results indicate only small differences in globally-averaged mean annual temperature and precipitation values, suggesting that all models have almost the same effect on the climate. There are differences, however, in how accurately each model reproduces the paleorecord. For example, in the Miocene simulations, when compared to the data of Wolfe (1985), the SDVM model underpredicts the presence of deciduous vegetation in North America, while the EVE model underpredicts the presence of coniferous forest in Eurasia. In the Last Glacial

  18. Species and endosymbiont diversity of Bemisia tabaci (Homoptera: Aleyrodidae) on vegetable crops in Senegal.

    PubMed

    Hélène, Delatte; Rémy, Baudin; Nathalie, Becker; Anne-Laure, Girard; Traoré, Ramatoulaye Sidebe; Jean-Michel, Lett; Bernard, Reynaud

    2015-03-01

    Bemisia tabaci-transmitted geminiviruses are one of the major threats on cassava and vegetable crops in Africa. However, to date, few studies are available on the diversity of B. tabaci and their associated endosymbionts in Africa. More than 28 species have been described in the complex of B. tabaci cryptic species; among them, 2 are invasive pests worldwide: MED and MEAM1. In order to assess the species diversity of B. tabaci in vegetable crops in Senegal, several samplings in different localities, hosts and seasons were collected and analyzed with nuclear (microsatellite) and mitochondrial (COI) markers. The bacterial endosymbiont community was also studied for each sample. Two species were detected: MED Q1 and MEAM1 B. Patterns of MED Q1 (dominance on most of the samples and sites, highest nuclear and mitochondrial diversity and broader secondary endosymbiont community: Hamiltonella, Cardinium, Wolbachia and Rickettsia), point toward a predominant resident begomovirus vector group for MED Q1 on market gardening crops. Furthermore, the lower prevalence of the second species MEAM1 B, its lower nuclear and mitochondrial diversity and a narrower secondary endosymbiont community (Hamiltonella/Rickettsia), indicate that this genetic group is exotic and results from a recent invasion in this area. © 2014 Institute of Zoology, Chinese Academy of Sciences.

  19. Contributions of Understory and/or Overstory Vegetations to Soil Microbial PLFA and Nematode Diversities in Eucalyptus Monocultures

    PubMed Central

    Liu, Zhanfeng; Zhou, Lixia; Fu, Shenglei

    2014-01-01

    Ecological interactions between aboveground and belowground biodiversity have received many attentions in the recent decades. Although soil biodiversity declined with the decrease of plant diversity, many previous studies found plant species identities were more important than plant diversity in controlling soil biodiversity. This study focused on the responses of soil biodiversity to the altering of plant functional groups, namely overstory and understory vegetations, rather than plant diversity gradient. We conducted an experiment by removing overstory and/or understory vegetation to compare their effects on soil microbial phospholipid fatty acid (PLFA) and nematode diversities in eucalyptus monocultures. Our results indicated that both overstory and understory vegetations could affect soil microbial PLFA and nematode diversities, which manifested as the decrease in Shannon–Wiener diversity index (H′) and Pielou evenness index (J) and the increase in Simpson dominance index (λ) after vegetation removal. Soil microclimate change explained part of variance of soil biodiversity indices. Both overstory and understory vegetations positively correlated with soil microbial PLFA and nematode diversities. In addition, the alteration of soil biodiversity might be due to a mixing effect of bottom-up control and soil microclimate change after vegetation removal in the studied plantations. Given the studied ecosystem is common in humid subtropical and tropical region of the world, our findings might have great potential to extrapolate to large scales and could be conducive to ecosystem management and service. PMID:24427315

  20. Contributions of understory and/or overstory vegetations to soil microbial PLFA and nematode diversities in Eucalyptus monocultures.

    PubMed

    Zhao, Jie; Wan, Songze; Zhang, Chenlu; Liu, Zhanfeng; Zhou, Lixia; Fu, Shenglei

    2014-01-01

    Ecological interactions between aboveground and belowground biodiversity have received many attentions in the recent decades. Although soil biodiversity declined with the decrease of plant diversity, many previous studies found plant species identities were more important than plant diversity in controlling soil biodiversity. This study focused on the responses of soil biodiversity to the altering of plant functional groups, namely overstory and understory vegetations, rather than plant diversity gradient. We conducted an experiment by removing overstory and/or understory vegetation to compare their effects on soil microbial phospholipid fatty acid (PLFA) and nematode diversities in eucalyptus monocultures. Our results indicated that both overstory and understory vegetations could affect soil microbial PLFA and nematode diversities, which manifested as the decrease in Shannon-Wiener diversity index (H') and Pielou evenness index (J) and the increase in Simpson dominance index (λ) after vegetation removal. Soil microclimate change explained part of variance of soil biodiversity indices. Both overstory and understory vegetations positively correlated with soil microbial PLFA and nematode diversities. In addition, the alteration of soil biodiversity might be due to a mixing effect of bottom-up control and soil microclimate change after vegetation removal in the studied plantations. Given the studied ecosystem is common in humid subtropical and tropical region of the world, our findings might have great potential to extrapolate to large scales and could be conducive to ecosystem management and service.

  1. Powdered hide model for vegetable tanning

    USDA-ARS?s Scientific Manuscript database

    Powdered hide samples for this initial study of vegetable tanning were prepared from hides that were dehaired by a typical sulfide or oxidative process, and carried through the delime/bate step of a tanning process. In this study, we report on interactions of the vegetable tannin, quebracho with th...

  2. 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

  3. Legume diversity patterns in West Central Africa: influence of species biology on distribution models.

    PubMed

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

    2012-01-01

    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. 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. 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

  4. Modeling Forest Structure and Vascular Plant Diversity in Piedmont Forests

    NASA Astrophysics Data System (ADS)

    Hakkenberg, C.

    2014-12-01

    When the interacting stressors of climate change and land cover/land use change (LCLUC) overwhelm ecosystem resilience to environmental and climatic variability, forest ecosystems are at increased risk of regime shifts and hyperdynamism in process rates. To meet the growing range of novel biotic and environmental stressors on human-impacted ecosystems, the maintenance of taxonomic diversity and functional redundancy in metacommunities has been proposed as a risk spreading measure ensuring that species critical to landscape ecosystem functioning are available for recruitment as local systems respond to novel conditions. This research is the first in a multi-part study to establish a dynamic, predictive model of the spatio-temporal dynamics of vascular plant diversity in North Carolina Piedmont mixed forests using remotely sensed data inputs. While remote sensing technologies are optimally suited to monitor LCLUC over large areas, direct approaches to the remote measurement of plant diversity remain a challenge. This study tests the efficacy of predicting indices of vascular plant diversity using remotely derived measures of forest structural heterogeneity from aerial LiDAR and high spatial resolution broadband optical imagery in addition to derived topo-environmental variables. Diversity distribution modelling of this sort is predicated upon the idea that environmental filtering of dispersing species help define fine-scale (permeable) environmental envelopes within which biotic structural and compositional factors drive competitive interactions that, in addition to background stochasticity, determine fine-scale alpha diversity. Results reveal that over a range of Piedmont forest communities, increasing structural complexity is positively correlated with measures of plant diversity, though the nature of this relationship varies by environmental conditions and community type. The diversity distribution model is parameterized and cross-validated using three high

  5. Galling arthropod diversity in adjacent swamp forests and restinga vegetation in Rio Grande do Sul, Brazil.

    PubMed

    Mendonça, Milton De S; Piccardi, Hosana M F; Jahnke, Simone M; Dalbem, Ricardo V

    2010-01-01

    Galling arthropods create plant structures inside which they find shelter. Factors acting on galler diversity are still being discussed, with this fauna considered more diverse in xeric than mesic environments (higrothermic stress hypothesis, HSH), and also in more plant diverse sites. Here we compare galler abundance (N), equitability (E), species richness (S) and composition between adjacent restinga (xeric) and swamp forests (mesic) in Parque Estadual de Itapeva (29°21' S, 49°45' W), Rio Grande do Sul, southern Brazil. Five trails, two in swamp forest and three in restingas, were sampled four times each (January/December 2005). After an effort of 60h/person, 621 galled plant individuals belonging to 104 gall morphotypes were recorded. This suggests a high galler diversity for the Park, comparable to the richest places known. No differences were found for N, E or S between restingas and swamp forests. However, faunal composition differs significantly between the vegetation types. The dominant (most abundant) species are different in either vegetation type, and are rare or absent on the other vegetation type. Such species composition analysis is still largely ignored for gallers, and stresses the fact that the HSH cannot explain this pattern, since the latter is based on preferences by the ovipositing galler for xeric sites instead of mesic ones. The two habitats differ in microclimate, but species richness, as would be predicted by the HSH, does not differ. This small scale pattern can perhaps be attributed to biogeographic processes on larger scales, as suggested by the resource synchronisation hypothesis.

  6. Diversity and composition of understory vegetation in the tropical seasonal rain forest of Xishuangbanna, SW China.

    PubMed

    Lü, Xiao-Tao; Yin, Jiang-Xia; Tang, Jian-Wei

    2011-03-01

    Tropical forests vegetation and community research have tended to focus on the tree component, and limited attention has been paid to understory vegetation. Species diversity and composition of the understory of tropical seasonal rain forest were inventoried in a 625 m2 area (for sapling layer) and a 100 m2 area (for herb/seedling layer) in three 1 ha plots. We found 3068 individuals belonging to 309 species, 192 genera and 89 families. The most important family as determined by the Family Importance Value (FIV) was Rubiaceae in both sapling and herb/seedling layers. In terms of Importance Value Index (IVI), the shrub Mycetia gracilis (Rubiaceae) was the most important species in the sapling layer and the pteridophyte Selaginella delicatula (Selaginellaceae) was the most ecological significant species in the herb/seedling layer. Much more vascular plant species were registered in the understory than in the tree layer totaled among the three plots. The species diversity did not differ significantly among the tree layer, sapling layer and herb/seedling layer. Given that we still know little about the understory plant community for growth forms other than trees, the results from the present study indicate that more attention should be paid to the understory vegetation during the decision-making process for biodiversity conservation in the tropical forests.

  7. A model of goal directed vegetable parenting practices

    USDA-ARS?s Scientific Manuscript database

    The aim of this study was to explore factors underlying parents' motivations to use vegetable parenting practices (VPP) using the Model of Goal Directed Vegetable Parenting Practices (MGDVPP) (an adaptation of the Model of Goal Directed Behavior) as the theoretical basis for qualitative interviews. ...

  8. Dynamic floodplain vegetation model development for the Kootenai River, USA.

    PubMed

    Benjankar, Rohan; Egger, Gregory; Jorde, Klaus; Goodwin, Peter; Glenn, Nancy F

    2011-12-01

    The Kootenai River floodplain in Idaho, USA, is nearly disconnected from its main channel due to levee construction and the operation of Libby Dam since 1972. The decreases in flood frequency and magnitude combined with the river modification have changed the physical processes and the dynamics of floodplain vegetation. This research describes the concept, methodologies and simulated results of the rule-based dynamic floodplain vegetation model "CASiMiR-vegetation" that is used to simulate the effect of hydrological alteration on vegetation dynamics. The vegetation dynamics are simulated based on existing theory but adapted to observed field data on the Kootenai River. The model simulates the changing vegetation patterns on an annual basis from an initial condition based on spatially distributed physical parameters such as shear stress, flood duration and height-over-base flow level. The model was calibrated and the robustness of the model was analyzed. The hydrodynamic (HD) models were used to simulate relevant physical processes representing historic, pre-dam, and post-dam conditions from different representative hydrographs. The general concept of the vegetation model is that a vegetation community will be recycled if the magnitude of a relevant physical parameter is greater than the threshold value for specific vegetation; otherwise, succession will take place toward maturation stage. The overall accuracy and agreement Kappa between simulated and field observed maps were low considering individual vegetation types in both calibration and validation areas. Overall accuracy (42% and 58%) and agreement between maps (0.18 and 0.27) increased notably when individual vegetation types were merged into vegetation phases in both calibration and validation areas, respectively. The area balance approach was used to analyze the proportion of area occupied by different vegetation phases in the simulated and observed map. The result showed the impact of the river

  9. Vegetation in Bangalore's Slums: Composition, Species Distribution, Density, Diversity, and History

    NASA Astrophysics Data System (ADS)

    Gopal, Divya; Nagendra, Harini; Manthey, Michael

    2015-06-01

    There is widespread acknowledgement of the need for biodiversity and greening to be part of urban sustainability efforts. Yet we know little about greenery in the context of urban poverty, particularly in slums, which constitute a significant challenge for inclusive development in many rapidly growing cities. We assessed the composition, density, diversity, and species distribution of vegetation in 44 slums of Bangalore, India, comparing these to published studies on vegetation diversity in other land-use categories. Most trees were native to the region, as compared to other land-use categories such as parks and streets which are dominated by introduced species. Of the most frequently encountered tree species, Moringa oleifera and Cocos nucifera are important for food, while Ficus religiosa plays a critical cultural and religious role. Tree density and diversity were much lower in slums compared to richer residential neighborhoods. There are also differences in species preferences, with most plant (herb, shrub and vines) species in slums having economic, food, medicinal, or cultural use, while the species planted in richer residential areas are largely ornamental. Historic development has had an impact on species distribution, with older slums having larger sized tree species, while recent slums were dominated by smaller sized tree species with greater economic and food use. Extensive focus on planting trees and plant species with utility value is required in these congested neighborhoods, to provide livelihood support.

  10. Vegetation in Bangalore's Slums: Composition, Species Distribution, Density, Diversity, and History.

    PubMed

    Gopal, Divya; Nagendra, Harini; Manthey, Michael

    2015-06-01

    There is widespread acknowledgement of the need for biodiversity and greening to be part of urban sustainability efforts. Yet we know little about greenery in the context of urban poverty, particularly in slums, which constitute a significant challenge for inclusive development in many rapidly growing cities. We assessed the composition, density, diversity, and species distribution of vegetation in 44 slums of Bangalore, India, comparing these to published studies on vegetation diversity in other land-use categories. Most trees were native to the region, as compared to other land-use categories such as parks and streets which are dominated by introduced species. Of the most frequently encountered tree species, Moringa oleifera and Cocos nucifera are important for food, while Ficus religiosa plays a critical cultural and religious role. Tree density and diversity were much lower in slums compared to richer residential neighborhoods. There are also differences in species preferences, with most plant (herb, shrub and vines) species in slums having economic, food, medicinal, or cultural use, while the species planted in richer residential areas are largely ornamental. Historic development has had an impact on species distribution, with older slums having larger sized tree species, while recent slums were dominated by smaller sized tree species with greater economic and food use. Extensive focus on planting trees and plant species with utility value is required in these congested neighborhoods, to provide livelihood support.

  11. Abundance, diversity and community composition of free-living protozoa on vegetable sprouts.

    PubMed

    Chavatte, N; Lambrecht, E; Van Damme, I; Sabbe, K; Houf, K

    2016-05-01

    Interactions with free-living protozoa (FLP) have been implicated in the persistence of pathogenic bacteria on food products. In order to assess the potential involvement of FLP in this contamination, detailed knowledge on their occurrence, abundance and diversity on food products is required. In the present study, enrichment and cultivation methods were used to inventory and quantify FLP on eight types of commercial vegetable sprouts (alfalfa, beetroot, cress, green pea, leek, mung bean, red cabbage and rosabi). In parallel, total aerobic bacteria and Escherichia coli counts were performed. The vegetable sprouts harbored diverse communities of FLP, with Tetrahymena (ciliate), Bodo saltans and cercomonads (flagellates), and Acanthamoeba and Vannella (amoebae) as the dominant taxa. Protozoan community composition and abundance significantly differed between the sprout types. Beetroot harbored the most abundant and diverse FLP communities, with many unique species such as Korotnevella sp., Vannella sp., Chilodonella sp., Podophrya sp. and Sphaerophrya sp. In contrast, mung bean sprouts were species-poor and had low FLP numbers. Sampling month and company had no significant influence, suggesting that seasonal and local factors are of minor importance. Likewise, no significant relationship between protozoan community composition and bacterial load was observed. Copyright © 2015 Elsevier Ltd. All rights reserved.

  12. Estimation of ecohydrological properties from inverse modeling of vegetation distributions

    NASA Astrophysics Data System (ADS)

    Thompson, S. E.; Katul, G. G.

    2012-12-01

    Spatial organization of vegetation into periodic, coherent patterns arises from the interaction of positive and negative ecohydrological feedbacks. The patterns reflect the characteristics of the interactions between plants and water that underlie their formation. Direct inference of the parameters describing these ecohydrological processes from observations of vegetation spatial patterns can facilitate the parameterization and predictive use of vegetation pattern models to predict water balance partitioning and desertification risk. An inference technique based on nonlinear filtering is proposed here and applied to estimate the parameters of a phenomenological model of vegetation biomass patterning. Results derived from modeled biomass data indicate that for sufficiently accurate biomass observations (signal to noise ratios >4), and spatial resolution of better than 10% of the pattern wavelength, nonlinear filtering techniques recovered model parameters with high fidelity. When applied to high resolution aerial photography, reasonable parameters within the pattern forming regime were inferred. The potential to extend these approaches to mechanistic models of vegetation distribution is discussed.

  13. Fire disturbance and vegetation dynamics : analysis and models

    NASA Astrophysics Data System (ADS)

    Thonicke, Kirsten

    2003-04-01

    Studies of the role of disturbance in vegetation or ecosystems showed that disturbances are an essential and intrinsic element of ecosystems that contribute substantially to ecosystem health, to structural diversity of ecosystems and to nutrient cycling at the local as well as global level. Fire as a grassland, bush or forest fire is a special disturbance agent, since it is caused by biotic as well abiotic environmental factors. Fire affects biogeochemical cycles and plays an important role in atmospheric chemistry by releasing climate-sensitive trace gases and aerosols, and thus in the global carbon cycle by releasing approximately 3.9 Gt C p.a. through biomass burning. A combined model to describe effects and feedbacks between fire and vegetation became relevant as changes in fire regimes due to land use and land management were observed and the global dimension of biomass burnt as an important carbon flux to the atmosphere, its influence on atmospheric chemistry and climate as well as vegetation dynamics were emphasized. The existing modelling approaches would not allow these investigations. As a consequence, an optimal set of variables that best describes fire occurrence, fire spread and its effects in ecosystems had to be defined, which can simulate observed fire regimes and help to analyse interactions between fire and vegetation dynamics as well as to allude to the reasons behind changing fire regimes. Especially, dynamic links between vegetation, climate and fire processes are required to analyse dynamic feedbacks and effects of changes of single environmental factors. This led us to the point, where new fire models had to be developed that would allow the investigations, mentioned above, and could help to improve our understanding of the role of fire in global ecology. In conclusion of the thesis, one can state that moisture conditions, its persistence over time and fuel load are the important components that describe global fire pattern. If time series of

  14. Remote Sensing of Vegetation Species Diversity: The Utility of Integrated Airborne Hyperspectral and Lidar Data

    NASA Astrophysics Data System (ADS)

    Krause, Keith Stuart

    The change, reduction, or extinction of species is a major issue currently facing the Earth. Efforts are underway to measure, monitor, and protect habitats that contain high species diversity. Remote sensing technology shows extreme value for monitoring species diversity by mapping ecosystems and using those land cover maps or other derived data as proxies to species number and distribution. The National Ecological Observatory Network (NEON) Airborne Observation Platform (AOP) consists of remote sensing instruments such as an imaging spectrometer, a full-waveform lidar, and a high-resolution color camera. AOP collected data over the Ordway-Swisher Biological Station (OSBS) in May 2014. A majority of the OSBS site is covered by the Sandhill ecosystem, which contains a very high diversity of vegetation species and is a native habitat for several threatened fauna species. The research presented here investigates ways to analyze the AOP data to map ecosystems at the OSBS site. The research attempts to leverage the high spatial resolution data and study the variability of the data within a ground plot scale along with integrating data from the different sensors. Mathematical features are derived from the data and brought into a decision tree classification algorithm (rpart), in order to create an ecosystem map for the site. The hyperspectral and lidar features serve as proxies for chemical, functional, and structural differences in the vegetation types for each of the ecosystems. K-folds cross validation shows a training accuracy of 91%, a validation accuracy of 78%, and a 66% accuracy using independent ground validation. The results presented here represent an important contribution to utilizing integrated hyperspectral and lidar remote sensing data for ecosystem mapping, by relating the spatial variability of the data within a ground plot scale to a collection of vegetation types that make up a given ecosystem.

  15. [The floristic diversity of the psammophyte vegetation in the region of Tlemcen (north-west Algeria)].

    PubMed

    Stambouli-Meziane, Hassiba; Bouazza, M; Thinon, Michel

    2009-08-01

    This study is devoted to the analysis of the psammophyte of the coastal and semi-continental dunes in Tlemcen. Interesting results have been obtained, in particular, on the biological and ecological aspects of the psammophyte. The interpretation from Factoriel analysis of correspondences enabled us to identify the different phytosociological classes (Cakiletea maritimae, Ammophiletea, Quercetea ilicis, Therobrachypodietea and Stellarietea mediae). Some of these classes (Cakiletea maritimae and Ammophiletea) inhabit, exceedingly well, the embryonic dunes. Some species (Therobrachypodietea) colonize the quickset dunes. Lastly, some others (Quercetea ilicis) settle in the more mature and stable dunes. By using the phytosociological and phytodynamical data, we have been able to understand the vegetation and its diversity.

  16. Discrete Random Media Techniques for Microwave Modeling of Vegetated Terrain

    NASA Technical Reports Server (NTRS)

    Lang, R. H. (Principal Investigator)

    1985-01-01

    Microwave remote sensing of vegetated terrain has been studied. Vegetation is modeled so that backscattered radar signals can be used to infer parameters which characterize the vegetation and underlying ground. The vegetation is modeled by discrete lossy dielectric scatterers with prescribed characteristics. The goal of the modeling effort is to remotely sense vegetation type (classification), growth stage, and plant/ground moisture. This information can then be used as input into agricultural, forestry and global circulation models. The microwave frequency spectrum, particularly L and C bands, are especially appropriate for this purpose since the wavelength is comparable to plant leaf and stem size. The resulting resonant interaction leads to backscattered data highly depend on plant shape and orientation. In addition, the transparent nature of the atmosphere in this frequency regime allows for algorithm development which requires no atmospheric correction.

  17. INTERCOMPARISON OF ALTERNATIVE VEGETATION DATABASES FOR REGIONAL AIR QUALITY MODELING

    EPA Science Inventory

    Vegetation cover data are used to characterize several regional air quality modeling processes, including the calculation of heat, moisture, and momentum fluxes with the Mesoscale Meteorological Model (MM5) and the estimate of biogenic volatile organic compound and nitric oxide...

  18. INTERCOMPARISON OF ALTERNATIVE VEGETATION DATABASES FOR REGIONAL AIR QUALITY MODELING

    EPA Science Inventory

    Vegetation cover data are used to characterize several regional air quality modeling processes, including the calculation of heat, moisture, and momentum fluxes with the Mesoscale Meteorological Model (MM5) and the estimate of biogenic volatile organic compound and nitric oxide...

  19. Next generation dynamic global vegetation models: learning from community ecology (Invited)

    NASA Astrophysics Data System (ADS)

    Scheiter, S.; Higgins, S.; Langan, L.

    2013-12-01

    Dynamic global vegetation models are a powerful tool to project past, current and future vegetation patterns and the associated biogeochemical cycles. However, most models are limited by their representation of vegetation by using static and pre-defined plant functional types and by their simplistic representation of competition. We discuss how concepts from community assembly theory and coexistence theory can help to improve dynamic vegetation models. We present a trait- and individual-based dynamic vegetation model, the aDGVM2, that allows individual plants to adopt a unique combination of trait values. These traits define how individual plants grow, compete and reproduce under the given biotic and abiotic conditions. A genetic optimization algorithm is used to simulate trait inheritance and reproductive isolation between individuals. These model properties allow the assembly of plant communities that are adapted to biotic and abiotic conditions. We show (1) that the aDGVM2 can simulate coarse vegetation patterns in Africa, (2) that changes in the environmental conditions and disturbances strongly influence trait diversity and the assembled plant communities by influencing traits such as leaf phenology and carbon allocation patterns of individual plants and (3) that communities do not necessarily return to the initial state when environmental conditions return to the initial state. The aDGVM2 deals with functional diversity and competition fundamentally differently from current models and allows novel insights as to how vegetation may respond to climate change. We believe that the aDGVM2 approach could foster collaborations between research communities that focus on functional plant ecology, plant competition, plant physiology and Earth system science.

  20. Patch-scale Representation of Vegetation within Hydraulic Models

    NASA Astrophysics Data System (ADS)

    Hardy, R. J.; Marjoribanks, T.; Lane, S. N.

    2016-12-01

    Submerged aquatic vegetation affects flow, sediment and ecological processes within rivers. Quantifying these effects is key to understanding the hydraulics and morphodynamics of natural river systems and implementing effective river management. Despite a wealth of research into vegetated flows, the detailed flow characteristics around real plants in natural channels are still poorly understood. Here we present a new methodology for representing vegetation patches within computational fluid dynamics (CFD) models of vegetated river channels. Vegetation is represented using a Mass Flux Scaling Algorithm (MFSA) and drag term within the Reynolds-Averaged Navier-Stokes Equations, which account for the mass and momentum effects of the vegetation respectively. The model is applied using three different grid resolutions (0.2, 0.1 & 0.05 m) using time-averaged solution methods and compared to field data. The results show that the model reproduces the complex spatial flow heterogeneity within the channel and that increasing the resolution leads to enhanced model accuracy. The model is able to reproduce with accuracy, commonly used reach-scale hydraulic metrics (Manning's n) but also provides spatial flow data which can be used to infer eco-geomorphic feedbacks and long term channel evolution. Specifically, the results demonstrate that while vegetation may cause both local erosion and deposition, at the reach-scale, vegetation can increase sedimentation by 50%.

  1. Development of a coupled wave-flow-vegetation interaction model

    USGS Publications Warehouse

    Beudin, Alexis; Kalra, Tarandeep; Ganju, Neil K.; Warner, John C.

    2017-01-01

    Emergent and submerged vegetation can significantly affect coastal hydrodynamics. However, most deterministic numerical models do not take into account their influence on currents, waves, and turbulence. In this paper, we describe the implementation of a wave-flow-vegetation module into a Coupled-Ocean-Atmosphere-Wave-Sediment Transport (COAWST) modeling system that includes a flow model (ROMS) and a wave model (SWAN), and illustrate various interacting processes using an idealized shallow basin application. The flow model has been modified to include plant posture-dependent three-dimensional drag, in-canopy wave-induced streaming, and production of turbulent kinetic energy and enstrophy to parameterize vertical mixing. The coupling framework has been updated to exchange vegetation-related variables between the flow model and the wave model to account for wave energy dissipation due to vegetation. This study i) demonstrates the validity of the plant posture-dependent drag parameterization against field measurements, ii) shows that the model is capable of reproducing the mean and turbulent flow field in the presence of vegetation as compared to various laboratory experiments, iii) provides insight into the flow-vegetation interaction through an analysis of the terms in the momentum balance, iv) describes the influence of a submerged vegetation patch on tidal currents and waves separately and combined, and v) proposes future directions for research and development.

  2. Development of a coupled wave-flow-vegetation interaction model

    NASA Astrophysics Data System (ADS)

    Beudin, Alexis; Kalra, Tarandeep S.; Ganju, Neil K.; Warner, John C.

    2017-03-01

    Emergent and submerged vegetation can significantly affect coastal hydrodynamics. However, most deterministic numerical models do not take into account their influence on currents, waves, and turbulence. In this paper, we describe the implementation of a wave-flow-vegetation module into a Coupled-Ocean-Atmosphere-Wave-Sediment Transport (COAWST) modeling system that includes a flow model (ROMS) and a wave model (SWAN), and illustrate various interacting processes using an idealized shallow basin application. The flow model has been modified to include plant posture-dependent three-dimensional drag, in-canopy wave-induced streaming, and production of turbulent kinetic energy and enstrophy to parameterize vertical mixing. The coupling framework has been updated to exchange vegetation-related variables between the flow model and the wave model to account for wave energy dissipation due to vegetation. This study i) demonstrates the validity of the plant posture-dependent drag parameterization against field measurements, ii) shows that the model is capable of reproducing the mean and turbulent flow field in the presence of vegetation as compared to various laboratory experiments, iii) provides insight into the flow-vegetation interaction through an analysis of the terms in the momentum balance, iv) describes the influence of a submerged vegetation patch on tidal currents and waves separately and combined, and v) proposes future directions for research and development.

  3. Bottom-up control of carabid beetle communities in early successional wetlands: mediated by vegetation structure or plant diversity?

    PubMed

    Brose, U

    2003-05-01

    Two hypotheses of bottom-up control that predict that the species richness of Carabidae will depend either on the taxonomic diversity of plants ("taxonomic diversity hypothesis") or on the structural heterogeneity of the vegetation ("structural heterogeneity hypothesis") were tested. Plant species were classified into nine plant structural groups through cluster analysis of morphological traits (e.g. total height) at 30 early successional temporary wetlands in the east-German agricultural landscape. In a linear regression analysis, the heterogeneity of vegetation structures explained 55% of the variation in carabid beetle diversity. According to a partial correlation analysis, plant taxonomic diversity did not have a significant effect, consistent with the "structural heterogeneity hypothesis," and contradicting previous studies which concluded that plant taxonomic diversity would be the most important factor in early successional habitats. An experimental study was used to test hypotheses on the processes underlying this bottom-up control by vegetation structure: the "hunting efficiency hypothesis," the "enemy-free space hypothesis," and the "microhabitat specialization hypothesis." The composition of plant structural groups in 15 vegetation plots (1 m(2)) was manipulated, creating a gradient from dense vegetation to open plots. Subsequent pitfall catches revealed significant differences in the activity-abundances of the carabid species. Large species preferred dense vegetation plots, consistent with the enemy-free space hypothesis that large species are more vulnerable to predation on the open plots and prefer dense vegetation to escape from natural enemies. The results indicate that bottom-up control is not mediated only by plant taxonomic or functional group diversity and that vegetation structures may be more important than previously suggested.

  4. Avian Communities in the Amazonian Cangas Vegetation: Biogeographic Affinities, Components of Beta-Diversity and Conservation.

    PubMed

    Borges, Sérgio H; Santos, Marcos P D; Soares, Leonardo M S; Silva, Antonita S DA

    2017-08-14

    The Amazonian cangas is a vegetation type distributed as patches of open vegetation embedded in a matrix of tropical forest and that grows over iron-rich soils in the Serra dos Carajás region. To characterize cangas avifauna, we surveyed birds in eight patches varying from 43 to 1,366 hectares. Cangas avifauna has compositional affinities with savannas widespread throughout the Amazon and other biomes, and we estimate that more than 200 bird species occurs in this habitat. Species composition was relatively homogeneous, and the similarity among cangas patches was the dominant component of the beta-diversity. Bird communities in cangas patches exhibited statistically significant nested structure in respect to species richness and patch size. In contrast, the nested site arrangement was not affected by the isolation of patches. Number of species and composition are moderately affected by the area of cangas patches but not by its degree of isolation. To conserve this unique habitat are necessary a strict protection of carefully chosen patches of cangas and an investigation of the conservation value of secondary vegetation recovered by the mining companies.

  5. Modeling Feedbacks Between Water and Vegetation in the Climate System

    NASA Technical Reports Server (NTRS)

    Miller, James R.; Russell, Gary L.; Hansen, James E. (Technical Monitor)

    2001-01-01

    Not only is water essential for life on earth, but life itself affects the global hydrologic cycle and consequently the climate of the planet. Whether the global feedbacks between life and the hydrologic cycle tend to stabilize the climate system about some equilibrium level is difficult to assess. We use a global climate model to examine how the presence of vegetation can affect the hydrologic cycle in a particular region. A control for the present climate is compared with a model experiment in which the Sahara Desert is replaced by vegetation in the form of trees and shrubs common to the Sahel region. A second model experiment is designed to identify the separate roles of two different effects of vegetation, namely the modified albedo and the presence of roots that can extract moisture from deeper soil layers. The results show that the presence of vegetation leads to increases in precipitation and soil moisture in western Sahara. In eastern Sahara, the changes are less clear. The increase in soil moisture is greater when the desert albedo is replaced by the vegetation albedo than when both the vegetation albedo and roots are added. The effect of roots is to withdraw water from deeper layers during the dry season. One implication of this study is that the insertion of vegetation into the Sahara modifies the hydrologic cycle so that the vegetation is more likely to persist than initially.

  6. Hydraulic and Vegetative Models of Historic Environmental Conditions Isolate the Role of Riparian Vegetation in Inducing Channel Change

    NASA Astrophysics Data System (ADS)

    Manners, R.; Schmidt, J. C.; Wheaton, J. M.

    2011-12-01

    An enduring question in geomorphology is the role of riparian vegetation in inducing or exacerbating channel narrowing. It is typically difficult to isolate the role of vegetation in causing channel narrowing, because narrowing typically occurs where there are changes in stream flow, sediment supply, the invasion of non-native vegetation, and sometimes climate change. Therefore, linkages between changes in vegetation communities and changes in channel form are often difficult to identify. We took a mechanistic approach to isolate the role of the invasive riparian shrub tamarisk (Tamarix spp) in influencing channel narrowing in the Colorado River basin. Detailed geomorphic reconstructions of two sites on the Yampa and Green Rivers, respectively, in Dinosaur National Monument show that channel narrowing has been progressive and that tamarisk encroachment has also occurred; at the same time, dams have been constructed, diversions increased, and spring snowmelt runoff has been occurring earlier in spring. We simulated hydraulic and sediment transport conditions during the two largest floods of record -- 1984 and 2011. Two-dimensional hydraulic models were built to reflect these conditions and allowed us to perform sensitivity tests to determine the dominant determinants of the observed patterns of erosion and deposition. Channel and floodplain topography were constrained through detailed stratigraphic analysis, including precise dating of deposits based on dating of buried tamarisk plants in a series of floodplain trenches and pits. We also used historical air photos to establish past channel topography. To parameterize the influence of riparian vegetation, we developed a model that links detailed terrestrial laser scan (TLS) measurements of stand structure and its corresponding hydraulic roughness at the patch scale to reach-scale riparian vegetation patterns determined from airborne LiDaR (ALS). This model, in conjunction with maps of the ages and establishment

  7. Discrete Random Media Techniques for Microwave Modeling of Vegetated Terrain

    NASA Technical Reports Server (NTRS)

    Lang, R. H.

    1984-01-01

    Microwave remote sensing of agricultural crops and forested regions is studied. Long term goals of the research involve modeling vegetation so that radar signatures can be used to infer the parameters which characterize the vegetation and underlying ground. Vegetation is modeled by discrete scatterers viz, leaves, stems, branches and trunks. These are replaced by glossy dielectric discs and cylinders. Rough surfaces are represented by their mean and spectral characteristics. Average scattered power is then calculated by employing discrete random media methodology such as the distorted Born approximation or transport theory. Both coherent and incoherent multiple scattering techniques are explored. Once direct methods are developed, inversion techniques can be investigated.

  8. Effects of experimental protocol on global vegetation model accuracy: a comparison of simulated and observed vegetation patterns for Asia

    USGS Publications Warehouse

    Tang, Guoping; Shafer, Sarah L.; Barlein, Patrick J.; Holman, Justin O.

    2009-01-01

    Prognostic vegetation models have been widely used to study the interactions between environmental change and biological systems. This study examines the sensitivity of vegetation model simulations to: (i) the selection of input climatologies representing different time periods and their associated atmospheric CO2 concentrations, (ii) the choice of observed vegetation data for evaluating the model results, and (iii) the methods used to compare simulated and observed vegetation. We use vegetation simulated for Asia by the equilibrium vegetation model BIOME4 as a typical example of vegetation model output. BIOME4 was run using 19 different climatologies and their associated atmospheric CO2 concentrations. The Kappa statistic, Fuzzy Kappa statistic and a newly developed map-comparison method, the Nomad index, were used to quantify the agreement between the biomes simulated under each scenario and the observed vegetation from three different global land- and tree-cover data sets: the global Potential Natural Vegetation data set (PNV), the Global Land Cover Characteristics data set (GLCC), and the Global Land Cover Facility data set (GLCF). The results indicate that the 30-year mean climatology (and its associated atmospheric CO2 concentration) for the time period immediately preceding the collection date of the observed vegetation data produce the most accurate vegetation simulations when compared with all three observed vegetation data sets. The study also indicates that the BIOME4-simulated vegetation for Asia more closely matches the PNV data than the other two observed vegetation data sets. Given the same observed data, the accuracy assessments of the BIOME4 simulations made using the Kappa, Fuzzy Kappa and Nomad index map-comparison methods agree well when the compared vegetation types consist of a large number of spatially continuous grid cells. The results of this analysis can assist model users in designing experimental protocols for simulating vegetation.

  9. Assessing global vegetation activity using spatio-temporal Bayesian modelling

    NASA Astrophysics Data System (ADS)

    Mulder, Vera L.; van Eck, Christel M.; Friedlingstein, Pierre; Regnier, Pierre A. G.

    2016-04-01

    This work demonstrates the potential of modelling vegetation activity using a hierarchical Bayesian spatio-temporal model. This approach allows modelling changes in vegetation and climate simultaneous in space and time. Changes of vegetation activity such as phenology are modelled as a dynamic process depending on climate variability in both space and time. Additionally, differences in observed vegetation status can be contributed to other abiotic ecosystem properties, e.g. soil and terrain properties. Although these properties do not change in time, they do change in space and may provide valuable information in addition to the climate dynamics. The spatio-temporal Bayesian models were calibrated at a regional scale because the local trends in space and time can be better captured by the model. The regional subsets were defined according to the SREX segmentation, as defined by the IPCC. Each region is considered being relatively homogeneous in terms of large-scale climate and biomes, still capturing small-scale (grid-cell level) variability. Modelling within these regions is hence expected to be less uncertain due to the absence of these large-scale patterns, compared to a global approach. This overall modelling approach allows the comparison of model behavior for the different regions and may provide insights on the main dynamic processes driving the interaction between vegetation and climate within different regions. The data employed in this study encompasses the global datasets for soil properties (SoilGrids), terrain properties (Global Relief Model based on SRTM DEM and ETOPO), monthly time series of satellite-derived vegetation indices (GIMMS NDVI3g) and climate variables (Princeton Meteorological Forcing Dataset). The findings proved the potential of a spatio-temporal Bayesian modelling approach for assessing vegetation dynamics, at a regional scale. The observed interrelationships of the employed data and the different spatial and temporal trends support

  10. Modeling the radiant transfers of sparse vegetation canopies

    NASA Technical Reports Server (NTRS)

    Kimes, D. S.; Norman, J. M.; Walthall, C. L.

    1985-01-01

    The scattering dynamics of sparse vegetation canopies were studied within the framework of the three-dimensional radiative transfer model of Kimes (1984). The model was upgraded by including an algorithm for the anisotropic scattering of a soil boundary. Validation of the model was carried out using measured directional reflectance data for two canopies exhibiting typical scattering behavior with low and intermediate vegetation density. The canopies were: an orchard grass canopy; and a hard wheat canopy. A number of factors were found contributing to the final reflectance distribution of the canopies, including: (1) the strong anisotropic scattering properties of the soil; (2) the geometric effect of the vegetation probability gap function on the soil anisotropy and solar irradiance; and (3) the anisotropic scattering of vegetation which is controlled by the phase function and the layering of leaves. The application of the theoretical results to the development of earth-observing sensor systems is discussed.

  11. Neogene and Quaternary history of vegetation, climate, and plant diversity in Amazonia

    NASA Astrophysics Data System (ADS)

    van der Hammen, Thomas; Hooghiemstra, Henry

    2000-04-01

    The neotropical Amazonian and Andean plant diversity developed mainly during the Tertiary. In Amazonia, Miocene floral diversity seems considerably higher than today. During the Neogene, tropical taxa entered newly created montane area, and montane taxa entered the tropical lowlands. The general decrease of temperature during the upper Neogene and especially during the Quaternary glacial periods may have caused considerable extinctions in the lowlands. Representation of pollen of apparently principally montane taxa ( Podocarpus, Hedyosmum) in Miocene, Pliocene, and Quaternary sediments of Amazonia and surroundings, is still difficult to interpret in terms of temperature decrease at low elevation. Changes in precipitation may have profound impact on the composition of vegetation communities; Ilex and Melastomataceae increase significantly in many glacial pollen records. Increase of Weinmannia in Amazonian pollen records seems the best indicator of downward migration of montane vegetation belts. A temperature lowering at sea-level of 4.5 ±1°C during the Last Glacial Maximum (LGM) seems reasonable; it may have caused a downslope migration of some 700 m of the lower montane vegetation belt; lower montane arboreal species may have been able to grow in higher elevation areas (>500 m) of Amazonia, increasing background pollen values of montane taxa in the area. Difference between a cool and wet Middle Pleniglacial (60-28 ka BP), and a cold and dry Upper Pleniglacial (28-14 ka BP; thus including the LGM) is evident in Andean and Amazonian records; statements about environmental conditions of the ice-age Amazon should be specified chronologically. The Middle Pleniglacial is a time of accumulation of fluvial sediments. The Upper Pleniglacial is a time of incision of the rivers in their sediments; sedimentation started again in the Lateglacial (since ca. 13 ka BP) and the Holocene, when lake levels rose again. Based on simplified considerations of precipitation changes and

  12. Modeling the beta diversity of coral reefs.

    PubMed

    Harborne, Alastair R; Mumby, Peter J; Zychaluk, Kamila; Hedley, John D; Blackwell, Paul G

    2006-11-01

    Quantifying the beta diversity (species replacement along spatiotemporal gradients) of ecosystems is important for understanding and conserving patterns of biodiversity. However, virtually all studies of beta diversity focus on one-dimensional transects orientated along a specific environmental gradient that is defined a priori. By ignoring a second spatial dimension and the associated changes in species composition and environmental gradients, this approach may provide limited insight into the full pattern of beta diversity. Here, we use remotely sensed imagery to quantify beta diversity continuously, in two dimensions, and at multiple scales across an entire tropical marine seascape. We then show that beta diversity can be modeled (0.852 > or = r2 > or = 0.590) at spatial scales between 0.5 and 5.0 km2, using the environmental variables of mean and variance of depth and wave exposure. Beta diversity, quantified within a "window" of a given size, is positively correlated to the range of environmental conditions within that window. For example, beta diversity increases with increasing variance of depth. By analyzing such relationships across seascapes, this study provides a framework for a range of disparate coral reef literature including studies of zonation, diversity, and disturbance. Using supporting evidence from soft-bottom communities, we hypothesize that depth will be an important variable for modeling beta diversity in a range of marine systems. We discuss the implications of our results for the design of marine reserves.

  13. Vegetation canopy PAR absorptance and the normalized difference vegetation index - An assessment using the SAIL model

    NASA Technical Reports Server (NTRS)

    Goward, Samuel N.; Huemmrich, Karl F.

    1992-01-01

    Relationships are studied between the normalized-difference vegetation index (NDVI) and absorbed photosynthetically active radiation (APAR) in a vegetation canopy. The SAIL model of bidirectional canopy radiative transfer is employed to compare NDVI measurements that are instantaneous with diurnally integrated canopy APAR capacity. The NDVI measurements - taken at solar-zenith angles of more than 60 deg and sensor views of less than 40 deg from nadir - give stable near-linear estimates of diurnal APAR capacity. Discrepancies in the relations between APAR and NDVI are associated with variations in the optical properties of the canopy and with background spectral reflectance. The results are significant for the practical use of these remote sensing techniques but suggest that instantaneous observations can be used to characterize the diurnally integrated APAR in vegetation canopies.

  14. Diversity in proteinase specificity of thermophilic lactobacilli as revealed by hydrolysis of dairy and vegetable proteins.

    PubMed

    Pescuma, Micaela; Espeche Turbay, María Beatriz; Mozzi, Fernanda; Font de Valdez, Graciela; Savoy de Giori, Graciela; Hebert, Elvira María

    2013-09-01

    Ability of industrially relevant species of thermophilic lactobacilli strains to hydrolyze proteins from animal (caseins and β-lactoglobulin) and vegetable (soybean and wheat) sources, as well as influence of peptide content of growth medium on cell envelope-associated proteinase (CEP) activity, was evaluated. Lactobacillus delbrueckii subsp. lactis (CRL 581 and 654), L. delbrueckii subsp. bulgaricus (CRL 454 and 656), Lactobacillus acidophilus (CRL 636 and 1063), and Lactobacillus helveticus (CRL 1062 and 1177) were grown in a chemically defined medium supplemented or not with 1 % Casitone. All strains hydrolyzed mainly β-casein, while degradation of αs-caseins was strain dependent. Contrariwise, κ-Casein was poorly degraded by the studied lactobacilli. β-Lactoglobulin was mainly hydrolyzed by CRL 656, CRL 636, and CRL 1062 strains. The L. delbrueckii subsp. lactis strains, L. delbrueckii subsp. bulgaricus CRL 656, and L. helveticus CRL 1177 degraded gliadins in high extent, while the L. acidophilus and L. helveticus strains highly hydrolyzed soy proteins. Proteinase production was inhibited by Casitone, the most affected being the L. delbrueckii subsp. lactis species. This study highlights the importance of proteolytic diversity of lactobacilli for rational strain selection when formulating hydrolyzed dairy or vegetable food products.

  15. Coupling groundwater and riparian vegetation models to assess effects of reservoir releases

    USGS Publications Warehouse

    Springer, A.E.; Wright, J.M.; Shafroth, P.B.; Stromberg, J.C.; Patten, D.T.

    1999-01-01

    Although riparian areas in the arid southwestern United States are critical for maintaining species diversity, their extent and health have been declining since Euro-American settlement. The purpose of this study was to develop a methodology to evaluate the potential for riparian vegetation restoration and groundwater recharge. A numerical groundwater flow model was coupled with a conceptual riparian vegetation model to predict hydrologic conditions favorable to maintaining riparian vegetation downstream of a reservoir. A Geographic Information System (GIS) was used for this one-way coupling. Constant and seasonally varying releases from the dam were simulated using volumes anticipated to be permitted by a regional water supplier. Simulations indicated that seasonally variable releases would produce surface flow 5.4-8.5 km below the dam in a previously dry reach. Using depth to groundwater simulations from the numerical flow model with conceptual models of depths to water necessary for maintenance of riparian vegetation, the GIS analysis predicted a 5- to 6.5-fold increase in the area capable of sustaining riparian vegetation.

  16. Multiscale Modeling of Wave-induced Flow in Vegetation Canopy

    NASA Astrophysics Data System (ADS)

    Zhu, L.; Chen, Q. J.; Chakrabarti, A.; Ma, G.

    2016-12-01

    Coastal vegetation dissipates the wave energy and alters local hydrodynamics by enhancing within-canopy turbulence, and introducing significant spatial variability to the flow. The modeling of flows and waves through vegetation has attracted the attention of coastal and hydraulics engineers for decades. The ability to predict instantaneous flow characteristics and turbulent flow structures accurately is of great significance for modeling wave attenuation and sediment transport in vegetated area. Two widely used types of modeling approaches are the Reynolds-averaged Navier-Stokes (RANS) and the Large Eddy Simulations (LES). The high level of detail delivered by the LES model comes with significantly large computational costs. The objective of this study is to investigate the flow structure and turbulence properties predicted by both methods and explore the applicability of multi-scale modeling of wave-induced flow in vegetation canopy. In this study, two models, NHWAVE and OpenFOAM, are utilized to simulate wave-induced flows in emergent and submerged vegetation. A standard k-ɛ turbulence model and a LES model are used in NHWAVE and OpenFOAM, respectively. NHWAVE employs a Morrison-type quadratic equation to approximate the wave-induced drag on vegetation stems, whereas OpenFOAM adopts a direct approach and resolves flow structure within the canopy using the high-resolution LES-based turbulence model. Both models are firstly validated against laboratory data for free surface and vertical variation of mean velocity. Reynolds stresses calculated directly from the LES model is compared with modeled Reynolds stresses from the RANS model and the influence of vertical variation of the turbulence structures on the mean canopy flow elucidated. Implications on wave energy dissipation and sediment transport are discussed.

  17. Tracking vegetation phenology across diverse North American biomes using PhenoCam imagery: A new, publicly-available dataset

    NASA Astrophysics Data System (ADS)

    Richardson, A. D.

    2015-12-01

    Vegetation phenology controls the seasonality of many ecosystem processes, as well as numerous biosphere-atmosphere feedbacks. Phenology is highly sensitive to climate change and variability, and is thus a key aspect of global change ecology. The goal of the PhenoCam network is to serve as a long-term, continental-scale, phenological observatory. The network uses repeat digital photography—images captured using conventional, visible-wavelength, automated digital cameras—to characterize vegetation phenology in diverse ecosystems across North America and around the world. At present, imagery from over 200 research sites, spanning a wide range of ecoregions, climate zones, and plant functional types, is currently being archived and processed in near-real-time through the PhenoCam project web page (http://phenocam.sr.unh.edu/). Data derived from PhenoCam imagery have been previously used to evaluate satellite phenology products, to constrain and test new phenology models, to understand relationships between canopy phenology and ecosystem processes, and to study the seasonal changes in leaf-level physiology that are associated with changes in leaf color. I will describe a new, publicly-available phenological dataset, derived from over 600 site-years of PhenoCam imagery. For each archived image (ca. 5 million), we extracted RGB (red, green, blue) color channel information, with means and other statistics calculated across a region-of-interest (ROI) delineating a specific vegetation type. From the high-frequency (typically, 30 minute) imagery, we derived time series characterizing vegetation color, including "canopy greenness", processed to 1- and 3-day intervals. For ecosystems with a single annual cycle of vegetation activity, we derived estimates, with uncertainties, for the start, middle, and end of spring and autumn phenological transitions. Given the lack of multi-year, standardized, and geographically distributed phenological data for North America, we

  18. Modelling of vegetation-driven morphodynamics in braided rivers.

    NASA Astrophysics Data System (ADS)

    Stecca, Guglielmo; Fedrizzi, Davide; Hicks, Murray; Measures, Richard; Zolezzi, Guido; Bertoldi, Walter; Tal, Michal

    2017-04-01

    River planform results from the complex interaction between flow, sediment transport and vegetation, and can evolve following a change in these controls. The braided planform of New Zealand's Lower Waitaki River, for instance, is endangered by the action of artificially-introduced alien vegetation, which spread across the braidplain following the reduction in magnitude of floods by hydropower dam construction. This vegetation, by encouraging flow concentration into the main channel, would likely promote a shift towards a single-thread morphology if it was not artificially removed within a central fairway. The purpose of this work is to study the evolution of braided rivers such as the Waitaki under different management scenarios through two-dimensional numerical modelling. The construction of a suitable model represents a task in itself, since a modelling framework coupling all the relevant processes is not yet readily available. Our starting point is the physics-based GIAMT2D numerical model, which solves two-dimensional flow and bedload transport in wet/dry domains, and recently modified by the inclusion of a rule-based bank erosion model. We have further developed this model by adding a vegetation module, which accounts in a simplified manner for time-evolving biomass density, adjusting local flow roughness, critical shear stress for sediment transport, and bank erodibility accordingly. Our goal is to use the model to study decadal-scale evolution of a reach on the Waitaki River and predict planform characteristics under different vegetation management scenarios. Here we present the results of a preliminary application of the model to reproduce the morphodynamic evolution of a braided channel in a set of flume experiments that used alfalfa as vegetation. The experiments began with a braided morphology that spontaneoulsy formed at constant flow over a bed of bare uniform sand. The planform transitioned towards single-thread when this discharge was repeatedly

  19. Modeling the interaction between flow and highly flexible aquatic vegetation

    NASA Astrophysics Data System (ADS)

    Dijkstra, J. T.; Uittenbogaard, R. E.

    2010-12-01

    Aquatic vegetation has an important role in estuaries and rivers by acting as bed stabilizer, filter, food source, and nursing area. However, macrophyte populations worldwide are under high anthropogenic pressure. Protection and restoration efforts will benefit from more insight into the interaction between vegetation, currents, waves, and sediment transport. Most aquatic plants are very flexible, implying that their shape and hence their drag and turbulence production depend on the flow conditions. We have developed a numerical simulation model that describes this dynamic interaction between very flexible vegetation and a time-varying flow, using the sea grass Zostera marina as an example. The model consists of two parts: an existing 1DV k-ɛ turbulence model simulating the flow combined with a new model simulating the bending of the plants, based on a force balance that takes account of both vegetation position and buoyancy. We validated this model using observations of positions of flexible plastic strips and of the forces they are subjected to, as well as hydrodynamic measurements. The model predicts important properties like the forces on plants, flow velocity profiles, and turbulence characteristics well. Although the validation data are limited, the results are sufficiently encouraging to consider our model to be of generic value in studying flow processes in fields of flexible vegetation.

  20. Modeling understory vegetation and its response to fire [Chapter 15

    Treesearch

    Donald McKenzie; Crystal L. Raymond; Samuel A. Cushman

    2008-01-01

    The understory is an oft-neglected element in landscape modeling. Most landscape models focus on the dominant vegetation and how it responds over successional time to climate, competitive interactions, and disturbance (Keane et al. 2004, Cary et al. 2006). Even forest stand-level models rarely consider understory components other than seedlings, saplings, and...

  1. [Soil moisture estimation model based on multiple vegetation index].

    PubMed

    Wu, Hai-long; Yu, Xin-xiao; Zhang, Zhen-ming; Zhang, Yan

    2014-06-01

    Estimating soil moisture conveniently and exactly is a hot issues in water resource monitoring among agriculture and forestry. Estimating soil moisture based on vegetation index has been recognized and applied widely. 8 vegetation indexes were figured out based on the hyper-spectral data measured by portable spectrometer. The higher correlation indexes among 8 vegetation indexes and surface vegetation temperature were selected by Gray Relative Analysis method (GRA). Then, these selected indexes were analyzed using Multiple Linear Regression to establish soil moisture estimation model based on multiple vegetation indexes, and the model accuracy was evaluated. The accuracy evaluation indicated that the fitting was satisfied and the significance was 0.000 (P < 0.001). High correlation was turned out between estimated and measured soil moisture with R2 reached 0.636 1 and RMSE 2.149 9. This method introduced multiple vegetation indexes into soil water content estimating over micro scale by non-contact measuring method using portable spectrometer. The exact estimation could be an appropriate replacement for remote sensing inversion and direct measurement. The model could estimate soil moisture quickly and accurately, and provide theory and technology reference for water resource management in agriculture and forestry.

  2. Genetic diversity amongst landraces of a dioecious vegetatively propagated plant, betelvine (Piper betle L.).

    PubMed

    Verma, Anjali; Kumar, Nikhil; Ranade, S A

    2004-09-01

    Betelvine (Piper betle L., family Piperaceae) is an important, traditional and widely cultivated crop of India. The cultivators and consumers recognize more than 100 cultivars (landraces) based on regional and organoleptic considerations, while in terms of phytochemical constituents only five groups have been identified for all the landraces. Since betelvine is an obligate vegetatively propagated species, genomic changes, if any, may have become 'fixed' in the landraces. We carried out random amplified polymorphic DNA (RAPD) analysis in several landraces considered in four groups, namely, 'Kapoori', 'Bangla', 'Sanchi' and 'Others' in order to ascertain their genetic diversity. On the basis of the data from eleven RAPD primers, we distinguished genetic variation within and among the four groups of landraces. The results indicate the 'Kapoori' group is the most diverse. The neighbour joining (NJ) tree after a bootstrap (500 replicate) test of robustness clearly shows the four groups to be well separated. Interestingly, all known male or female betelvine landraces have separated in the NJ tree indicating an apparent gender-based distinction among the betelvines.

  3. Stochastic models of cover class dynamics. [remote sensing of vegetation

    NASA Technical Reports Server (NTRS)

    Barringer, T. H.; Robinson, V. B.

    1981-01-01

    Investigations related to satellite remote sensing of vegetation have been concerned with questions of signature identification and extension, cover inventory accuracy, and change detection and monitoring. Attention is given to models of ecological succession, present directions in successional modeling and analysis, nondynamic spatial models, issues in the analysis of spatial data, and aspects of spatial modeling. Issues in time-series analysis are considered along with dynamic spatial models, and problems of model specification and identification.

  4. [Simulation of vegetation indices optimizing under retrieval of vegetation biochemical parameters based on PROSPECT + SAIL model].

    PubMed

    Wu, Ling; Liu, Xiang-Nan; Zhou, Bo-Tian; Liu, Chuan-Hao; Li, Lu-Feng

    2012-12-01

    This study analyzed the sensitivities of three vegetation biochemical parameters [chlorophyll content (Cab), leaf water content (Cw), and leaf area index (LAI)] to the changes of canopy reflectance, with the effects of each parameter on the wavelength regions of canopy reflectance considered, and selected three vegetation indices as the optimization comparison targets of cost function. Then, the Cab, Cw, and LAI were estimated, based on the particle swarm optimization algorithm and PROSPECT + SAIL model. The results showed that retrieval efficiency with vegetation indices as the optimization comparison targets of cost function was better than that with all spectral reflectance. The correlation coefficients (R2) between the measured and estimated values of Cab, Cw, and LAI were 90.8%, 95.7%, and 99.7%, and the root mean square errors of Cab, Cw, and LAI were 4.73 microg x cm(-2), 0.001 g x cm(-2), and 0.08, respectively. It was suggested that to adopt vegetation indices as the optimization comparison targets of cost function could effectively improve the efficiency and precision of the retrieval of biochemical parameters based on PROSPECT + SAIL model.

  5. Development of the IAP Dynamic Global Vegetation Model

    NASA Astrophysics Data System (ADS)

    Zeng, Xiaodong; Li, Fang; Song, Xiang

    2014-05-01

    The IAP Dynamic Global Vegetation Model (IAP-DGVM) has been developed to simulate the distribution and structure of global vegetation within the framework of Earth System Models. It incorporates our group's recent developments of major model components such as the shrub sub-model, establishment and competition parameterization schemes, and a process-based fire parameterization of intermediate complexity. The model has 12 plant functional types, including seven tree, two shrub, and three grass types, plus bare soil. Different PFTs are allowed to coexist within a grid cell, and their state variables are updated by various governing equations describing vegetation processes from fine-scale biogeophysics and biogeochemistry, to individual and population dynamics, to large-scale biogeography. Environmental disturbance due to fire not only affects regional vegetation competition, but also influences atmospheric chemistry and aerosol emissions. Simulations under observed atmospheric conditions showed that the model can correctly reproduce the global distribution of trees, shrubs, grasses, and bare soil. The simulated global dominant vegetation types reproduce the transition from forest to grassland (savanna) in the tropical region, and from forest to shrubland in the boreal region, but overestimate the region of temperate forest.

  6. Multi vegetation model evaluation of the Green Sahara climate regime

    NASA Astrophysics Data System (ADS)

    Hopcroft, Peter O.; Valdes, Paul J.; Harper, Anna B.; Beerling, David J.

    2017-07-01

    During the Quaternary, the Sahara desert was periodically colonized by vegetation, likely because of orbitally induced rainfall increases. However, the estimated hydrological change is not reproduced in climate model simulations, undermining confidence in projections of future rainfall. We evaluated the relationship between the qualitative information on past vegetation coverage and climate for the mid-Holocene using three different dynamic vegetation models. Compared with two available vegetation reconstructions, the models require 500-800 mm of rainfall over 20°-25°N, which is significantly larger than inferred from pollen but largely in agreement with more recent leaf wax biomarker reconstructions. The magnitude of the response also suggests that required rainfall regime of the early to middle Holocene is far from being correctly represented in general circulation models. However, intermodel differences related to moisture stress parameterizations, biases in simulated present-day vegetation, and uncertainties about paleosoil distributions introduce uncertainties, and these are also relevant to Earth system model simulations of African humid periods.

  7. Paleocene floral diversities and turnover events in eastern North America and their relation to diversity models

    USGS Publications Warehouse

    Frederiksen, N.O.

    1994-01-01

    This paper uses angiosperm pollen taxon turnover (first and last appearance) and diversity events as metrics to describe the Paleocene floral history of the eastern Gulf Coast; data are from 64 samples and 67 angiosperm pollen taxa. Angiosperm pollen diversity was very low at the beginning of the Paleocene, rose slowly and then somewhat more rapidly to a maximum for the epoch in the middle of the late Paleoceneas a result of the maximum in rate of first appearances during the late early Paleocene and earliest late Paleocene. Diversity then dropped very rapidly at or near the end of the epoch as the rate of last appearances reached its maximum, resulting in the Terminal Paleocene Extinction Event. The latest Paleocene diversity decline coincided with an increase in mean annual temperature and probably in rainfall, representing the beginning of the climatic maximum for the Tertiary which characterized the early Eocene. The increase in diversity of early Paleocene floras in the eastern Gulf Coast resulted from exploitation of unfilled ecospace originating from (1) low regional diversity following the Terminal Cretaceous Extinction Event, and (2) creation of many new niches during the Paleocene, resulting, according to megafloral evidence, from a change to a new vegetation type (multistratal tropical rainforest) brought about by an increase in rainfall. The slow rate of recovery of earliest Paleocene angiosperm diversity in the eastern Gulf Coast may be explained in part by the diversity-dependence model of Carr and Kitchell (1980). However, additional factors may have contributed to the slow recovery: (1) the adverse terminal Cretaceous climates may have extended into the early Paleocene, (2) the initial Paleocene environment of the eastern Gulf Coast may have contained relatively few niches, (3) some earliest Paleocene angiosperms, particularly trees, may have had inherently poor capabilities for rapid evolution, and (4) there was a lack of significant immigration of

  8. Managing for diversity: harvest gap size drives complex light, vegetation, and deer herbivory impacts on tree seedlings

    Treesearch

    Michael B. Walters; Evan J. Farinosi; John L. Willis; Kurt W. Gottschalk

    2016-01-01

    Many managed northern hardwood forests are characterized by low-diversity tree regeneration. Small harvest gaps, competition from shrub–herb vegetation, and browsing by white-tailed deer (Odocoileus virginianus) contribute to this pattern, but we know little about how these factors interact. With a stand-scale experiment, we examined the effects of...

  9. Microbial biomass and bacterial functional diversity in forest soils: effects of organic matter removal, compaction, and vegetation control

    Treesearch

    Qingchao Li; H. Lee Allen; Arthur G. Wollum

    2004-01-01

    The effects of organic matter removal, soil compaction, and vegetation control on soil microbial biomass carbon, nitrogen, C-to-N ratio, and functional diversity were examined in a 6-year loblolly pine plantation on a Coastal Plain site in eastern North Carolina, USA. This experimental plantation was established as part of the US Forest Service's Long Term Soil...

  10. The influence of vegetational diversity on the population ecology of a specialized herbivore, Phyllotreta cruciferae (Coleoptera: Chrysomelidae).

    PubMed

    Tahvanainen, Jorma O; Root, Richard B

    1972-12-01

    The population ecology of Phyllotreta cruciferae Goeze, a flea beetle which is an important pest of cole crops (Brassica oleracea) in central New York was studied in experimental gardens of differing vegetational diversity over a three year period. Adult beetles were more abundant on collards (B. oleracea var. acephala) grown in monocultures than on those grown adjacent to natural vegetation. The emergence of individuals forming the new annual generation was also greater in the pure stands. Predators and parasites appeared to have a negligible influence on the adult beetles in both habitats. Further experiments demonstrated that monocultures were colonized more rapidly and experienced greater feeding damage than stands in which collards had been interplanted with tomatoes and tobacco. Choice experiments in the laboratory showed that chemical stimuli given off by non-host plants (tomato, Lycopersicon esculentum, and ragweed, Ambrosia artemisiifolia) interfered with the host finding and feeding behaviour of P. cruciferae. These results indicate that vegetational diversity can exert a direct influence on populations of phytophagous insects.We conclude that the environmental capacity (Determination in Schwerdtfeger's terminology) of diverse natural communities is lower than that of natural or man-made monocultures. The "associational resistance" resulting from the higher taxonomic and microclimatic complexity of natural vegetation tends to reduce outbreaks of herbivores in diverse communities.

  11. Effects of temperature seasonality on tundra vegetation productivity using a daily vegetation dynamics model

    NASA Astrophysics Data System (ADS)

    Epstein, H. E.; Erler, A.; Frazier, J.; Bhatt, U. S.

    2011-12-01

    Changes in the seasonality of air temperature will elicit interacting effects on the dynamics of snow cover, nutrient availability, vegetation growth, and other ecosystem properties and processes in arctic tundra. Simulation models often do not have the fine temporal resolution necessary to develop theory and propose hypotheses for the effects of daily and weekly timescale changes on ecosystem dynamics. We therefore developed a daily version of an arctic tundra vegetation dynamics model (ArcVeg) to simulate how changes in the seasonality of air temperatures influences the dynamics of vegetation growth and carbon sequestration across regions of arctic tundra. High temporal-resolution air and soil temperature data collected from field sites across the five arctic tundra bioclimate subzones were used to develop a daily weather generator operable for sites throughout the arctic tundra. Empirical relationships between temperature and soil nitrogen were used to generate daily dynamics of soil nitrogen availability, which drive the daily uptake of nitrogen and growth among twelve tundra plant functional types. Seasonal dynamics of the remotely sensed normalized difference vegetation index (NDVI) and remotely sensed land surface temperature from the Advanced Very High Resolution Radiometer (AVHRR) GIMMS 3g dataset were used to investigate constraints on the start of the growing season, although there was no indication of any spatially consistent temperature or day-length controls on greening onset. Because of the exponential nature of the relationship between soil temperature and nitrogen mineralization, temperature changes during the peak of the growing season had greater effects on vegetation productivity than changes earlier in the growing season. However, early season changes in temperature had a greater effect on the relative productivities of different plant functional types, with potential influences on species composition.

  12. A trait-based approach in modeling fluxes to and from vegetation in ESM projections

    NASA Astrophysics Data System (ADS)

    Verheijen, Lieneke; Brovkin, Victor; Aerts, Rien; van Bodegom, Peter

    2013-04-01

    Large uncertainties exist in projections of earth system models (ESMs) both with respect to the size and direction of change in terrestrial carbon pools, as well as to how vegetation will respond (e.g. diebacks). These uncertainties may be partly explained by differences in the way biophysical or biochemical vegetation processes and disturbances are modeled, which may affect carbon exchange between the terrestrial biosphere and the atmosphere. Most models only contain a limited number of Plant functional types (PFTs) to represent the vast diversity in vascular plants. The currently static nature of PFT properties contrasts with the variation seen in natural vegetation, where plants adjust their traits in response to environmental change. As PFTs remain relatively inert under changing climatic conditions, they do not allow for such plant adaptation to the environment and plant-atmosphere feedbacks, with unknown consequences for model projections. A way to solve this problem is to allow traits of PFTs to vary with environmental conditions. This can be achieved by implementing trait-climate relationships based on the ecological concept of habitat filtering, where abiotic conditions act as a filter and reduce the number of viable plant traits in a habitat, resulting in different community means across global environmental gradients. In this project, such relationships were incorporation in the DGVM JSBACH to allow for variable traits in PFT-means within grid cells. As projections concern elevated CO2 concentrations, plant CO2 adaptation was modeled as well, based on long-term FACE-experiments. Simulations were performed with and without increasing CO2 affecting vegetation to disentangle the effects of climate and CO2 fertilization on vegetation. Equilibrium simulations with and without plant adaptation via variable traits already showed large differences in patterns of vegetation and productivity, with the model with variable traits performing better than the default

  13. Modelling tundra vegetation response to recent arctic warming.

    PubMed

    Miller, Paul A; Smith, Benjamin

    2012-01-01

    The Arctic land area has warmed by > 1 °C in the last 30 years and there is evidence that this has led to increased productivity and stature of tundra vegetation and reduced albedo, effecting a positive (amplifying) feedback to climate warming. We applied an individual-based dynamic vegetation model over the Arctic forced by observed climate and atmospheric CO(2) for 1980-2006. Averaged over the study area, the model simulated increases in primary production and leaf area index, and an increasing representation of shrubs and trees in vegetation. The main underlying mechanism was a warming-driven increase in growing season length, enhancing the production of shrubs and trees to the detriment of shaded ground-level vegetation. The simulated vegetation changes were estimated to correspond to a 1.75 % decline in snow-season albedo. Implications for modelling future climate impacts on Arctic ecosystems and for the incorporation of biogeophysical feedback mechanisms in Arctic system models are discussed.

  14. A regional dynamic vegetation-climate model for Central America

    NASA Astrophysics Data System (ADS)

    Snell, R. S.; Cowling, S. A.; Smith, B.

    2009-12-01

    Global vegetation models simulate the distribution of vegetation as a function of climate. Dynamic global vegetation models (DGVMs) are also able to simulate the vegetation shifts in response to climate change, which makes them particularly useful for addressing questions about past and future climate scenarios. However, DGVMs have been criticized for using generic plant functional types (PFTs) and running the models at a coarse grid cell resolution. Regional dynamic vegetation models are able to simulate important landscape variation, since they use a finer resolution and specific PFTs for their region. Regional studies have typically focused on boreal or temperate ecosystems in North America and Europe. We will be presenting the results of applying a dynamic regional vegetation-climate model (LPJ-GUESS) for Central America. Initially, the model was run with the described global PFTs. However, several biomes were very poorly represented. Two PFTs were added: a Tropical Needleleaf Evergreen Tree to improve the simulation of the Mixed Pine-Oak biome, and a Desert Shrub to capture the Xeric Shrublands. The overall distribution of biomes was visually similar, however the Kappa statistic indicated a poor agreement with the potential biome map (overall Kappa = 0.301). The Kappa statistic did improve as we aggregated cell sizes and simplified the biomes (overall Kappa = 0.728). Compared to remote sensing data, the model showed a strong correlation with total LAI (r = 0.75). The poor Kappa statistic is likely due to a combination of factors. The way in which biomes are defined by the author can have a large influence on the level of agreement between simulated and potential vegetation. The Kappa statistic is also limited to comparing individual grid cells and thus, cannot detect overall patterns. Examining those areas which are poorly represented will help to identify future work and improve the representation of vegetation in these ecological models. In particular, the

  15. Vegetative reproduction and clonal diversity in Rhytidium rugosum (Rhytidiaceae, Bryopsida) inferred by morpho-anatomical and molecular analyses.

    PubMed

    Pfeiffer, Tanja; Fritz, Sebastian; Stech, Michael; Frey, Wolfgang

    2006-03-01

    Many bryophytes exhibit specific life forms that result in the formation of distinct patches. This is primarily achieved by "consequent vegetative multiplication" through indeterminate growth and vegetative reproduction. Little, however, is known about the underlying mechanisms and genetic patterns. In this study on vegetative multiplication in bryophytes, we apply morpho-anatomical and molecular (AFLP fingerprinting) techniques to analyze the vegetative reproduction system, clonal diversity, and habitat colonization of a pleurocarpous moss, Rhytidium rugosum (Rhytidiaceae). Morpho-anatomically, three types of vegetative diaspores are identified and illustrated: ramets, separated after decay and disintegration of older shoot parts (clonal reproduction); brood branches/branchlets; and caducous shoot apices (both vegetative reproduction s.str.). The AFLP fingerprinting of 35 samples (from two plots in Thuringia, further German populations, and from France, Russia, and Canada) resulted in the identification of three clones from the two plots, each comprising two to 15 samples with identical fingerprints. Samples from one clone occurred in both plots, thus proving dispersal of vegetative diaspores. The AFLP analysis further revealed close relationships of the plot samples, which suggest a clonal rather than generative (sexual) origin of the population.

  16. Dynamical vegetation-atmosphere modelling of the boreal zone

    NASA Astrophysics Data System (ADS)

    Tang, Hui; Stordal, Frode; Berntsen, Terje K.; Bryn, Anders

    2016-04-01

    Vegetation interacts with climate on seasonal to inter-annual time scales through albedo, roughness, evapotranspiration, CO2 sequestration and by influencing snow accumulation and ablation. The Scandinavian mountains and high latitudes is a hot spot for land-atmosphere feedback, as the future's increased winter minimum temperature supports a boreal tree line advance, lowering the surface albedo. The northern ecosystem is dominated by mires, boreal forests and alpine heaths, in addition to agricultural land. Model studies have shown that vegetation-climate feedbacks are strong enough to lead to regime shifts in vegetation and local climate in boreal regions. Biogeophysical factors, such as albedo, the Bowen ratio, and surface roughness, are all involved in these feedbacks, and they are also altered by land use change such as reforestation. For calculations of the dynamical coupling between the atmosphere and the vegetation we have used the Earth System Model NorESM, which includes several advanced features in its land surface model (CLM4.5), such as the inclusion of the radiative forcing due to black carbon and dust deposit onto snow, improved representation of fire, permafrost and its hydrological impact, a new snow cover fraction parameterization reflecting the hysteresis in fractional snow cover for a given snow depth between accumulation and melt phases, as well as dynamic vegetation coupled with carbon-nitrogen cycles. These new features improve the representation of surface albedo feedback in Arctic. We have performed experiments with coupled as well fixed ocean for the current as a quadrupled atmospheric CO2 situation. This model configuration is used to study changes in vegetation in a high end radiative forcing case. It is contrasted with an experiment where vegetation dynamics is neglected. Changes in the features of the vegetation along with surface fluxes, albedo and atmospheric temperatures are analysed, with main emphasis on the boreal zone. In

  17. Modeling soil water content for vegetation modeling improvement

    NASA Astrophysics Data System (ADS)

    Cianfrani, Carmen; Buri, Aline; Zingg, Barbara; Vittoz, Pascal; Verrecchia, Eric; Guisan, Antoine

    2016-04-01

    adjusted-R2 ranging from 0.55 to 0.65. Bivariate models with higher performance were the one using OM and river distance for pF < 2.7 and the one using clay content and topography (convexity) for pF > 2.7.We found that adding SWC improves vegetation models. It improves 51%-64% (depending on pF) of plant SDMs. In 6-10% of SDMs, SWC was the most important variable. In conclusion, this study emphasized that important information is still missing in SDMs to capture all abiotic drivers of plant species distributions.

  18. Using Ecosystem Experiments to Improve Vegetation Models

    SciTech Connect

    Medlyn, Belinda; Zaehle, S; DeKauwe, Martin G.; Walker, Anthony P.; Dietze, Michael; Hanson, Paul J.; Hickler, Thomas; Jain, Atul; Luo, Yiqi; Parton, William; Prentice, I. Collin; Thornton, Peter E.; Wang, Shusen; Wang, Yingping; Weng, Ensheng; Iversen, Colleen M.; McCarthy, Heather R.; Warren, Jeffrey; Oren, Ram; Norby, Richard J

    2015-05-21

    Ecosystem responses to rising CO2 concentrations are a major source of uncertainty in climate change projections. Data from ecosystem-scale Free-Air CO2 Enrichment (FACE) experiments provide a unique opportunity to reduce this uncertainty. The recent FACE Model–Data Synthesis project aimed to use the information gathered in two forest FACE experiments to assess and improve land ecosystem models. A new 'assumption-centred' model intercomparison approach was used, in which participating models were evaluated against experimental data based on the ways in which they represent key ecological processes. Identifying and evaluating the main assumptions caused differences among models, and the assumption-centered approach produced a clear roadmap for reducing model uncertainty. We explain this approach and summarize the resulting research agenda. We encourage the application of this approach in other model intercomparison projects to fundamentally improve predictive understanding of the Earth system.

  19. Using Ecosystem Experiments to Improve Vegetation Models

    DOE PAGES

    Medlyn, Belinda; Zaehle, S; DeKauwe, Martin G.; ...

    2015-05-21

    Ecosystem responses to rising CO2 concentrations are a major source of uncertainty in climate change projections. Data from ecosystem-scale Free-Air CO2 Enrichment (FACE) experiments provide a unique opportunity to reduce this uncertainty. The recent FACE Model–Data Synthesis project aimed to use the information gathered in two forest FACE experiments to assess and improve land ecosystem models. A new 'assumption-centred' model intercomparison approach was used, in which participating models were evaluated against experimental data based on the ways in which they represent key ecological processes. Identifying and evaluating the main assumptions caused differences among models, and the assumption-centered approach produced amore » clear roadmap for reducing model uncertainty. We explain this approach and summarize the resulting research agenda. We encourage the application of this approach in other model intercomparison projects to fundamentally improve predictive understanding of the Earth system.« less

  20. A coupled vegetation/sediment transport model for dryland environments

    NASA Astrophysics Data System (ADS)

    Mayaud, Jerome R.; Bailey, Richard M.; Wiggs, Giles F. S.

    2017-04-01

    Dryland regions are characterized by patchy vegetation, erodible surfaces, and erosive aeolian processes. Understanding how these constituent factors interact and shape landscape evolution is critical for managing potential environmental and anthropogenic impacts in drylands. However, modeling wind erosion on partially vegetated surfaces is a complex problem that has remained challenging for researchers. We present the new, coupled cellular automaton Vegetation and Sediment TrAnsport (ViSTA) model, which is designed to address fundamental questions about the development of arid and semiarid landscapes in a spatially explicit way. The technical aspects of the ViSTA model are described, including a new method for directly imposing oblique wind and transport directions onto a cell-based domain. Verification tests for the model are reported, including stable state solutions, the impact of drought and fire stress, wake flow dynamics, temporal scaling issues, and the impact of feedbacks between sediment movement and vegetation growth on landscape morphology. The model is then used to simulate an equilibrium nebkha dune field, and the resultant bed forms are shown to have very similar size and spacing characteristics to nebkhas observed in the Skeleton Coast, Namibia. The ViSTA model is a versatile geomorphological tool that could be used to predict threshold-related transitions in a range of dryland ecogeomorphic systems.

  1. Analyzing Groundwater-Vegetation Interactions using a Dynamic Agroecosystem Model

    NASA Astrophysics Data System (ADS)

    Soylu, M. E.; Kucharik, C. J.; Loheide, S. P.

    2012-12-01

    Groundwater is a crucial source of water for vegetation, especially in arid and semiarid environments in many regions around the world and its availability controls the distribution and the physiology of plant species. However, the impact of groundwater on vegetation is not completely understood mainly due to the limited ability of current models to simulate groundwater and vegetation interactions. Existing land surface models (LSM) simulate water and energy fluxes among soil-vegetation-atmosphere systems in a process-based way, but lack a detailed simulation of soil water movement in the unsaturated zone, particularly when groundwater is present. Furthermore, there are only a few available LSM and/or process based vegetation models that can simulate agroecosystems, which are as important to understand as natural ecosystems considering they occupy approximately 40% of the global land surface. On the other hand, current physically-based, variably-saturated soil water flux models are able to accurately simulate water movement in the unsaturated zone. However, they often lack a detailed plant physiology component making it difficult to understand plant responses to both variations in energy fluxes and upward capillary fluxes in shallow groundwater environments. To connect these two different model types, the objectives of this study are (1) to incorporate an advanced dynamic agroecosystem model (Agro-IBIS) and a variably saturated soil water flow model (Hydrus-1D) into a single framework that is capable of simulating groundwater and plant/crop system interactions in a fully, physically-based fashion, and (2) to apply this model using observed climate records to better understand the responses of managed and natural ecosystems to varied water table depths under inter-annual climate forcing conditions. The model results show that as the water table becomes shallower, (1) soil temperature decreases due to the moisture content driven effects on the thermal diffusivity of

  2. Predicting Use of Ineffective Responsive, Structure and Control Vegetable Parenting Practices with the Model of Goal Directed Behavior.

    PubMed

    Baranowski, Tom; Beltran, Alicia; Chen, Tzu-An; Thompson, Debbe; O'Connor, Teresia; Hughes, Sheryl; Diep, Cassandra; Baranowski, Janice C

    This study reports the modeling of three categories of ineffective vegetable parenting practices (IVPP) separately (responsive, structure, and control vegetable parenting practices). An internet survey was employed for a cross sectional assessment of parenting practices and cognitive-emotional variables. Parents (n=307) of preschool children (3-5 years old) were recruited through announcements and postings. Models were analyzed with block regression and backward deletion procedures using a composite IVPP scale as the dependent variable. The independent variables included validated scales from a Model of Goal Directed Vegetable Parenting Practices (MGDVPP), including: intention, habit, perceived barriers, desire, competence, autonomy, relatedness, attitudes, norms, perceived behavioral control, and anticipated emotions. The available scales accounted for 26.5%, 16.7% and 44.6% of the variance in the IVPP responsive, structure and control subscales, respectively. Different sets of diverse variables predicted the three IVPP constructs. Intentions, Habits and Perceived Behavioral Control were strong predictors for each of the IVPP constructs, but the subscales were specific to each IVPP construct. Parent emotional responses, an infrequently investigated variable, was an important predictor of ineffective responsive vegetable parenting practices and ineffective structure vegetable parenting practices, but not ineffective control vegetable parenting practices. An Attitude subscale and a Norms subscale predicted ineffective responsive vegetable parenting practices alone. This was the first report of psychometrically tested scales to predict use of IVPP subscales. Further research is needed to verify these findings in larger longitudinal cohorts. Interventions to increase child vegetable intake may have to reduce IVPP.

  3. Emergence of diversity in a model ecosystem

    NASA Astrophysics Data System (ADS)

    Mitarai, Namiko; Mathiesen, Joachim; Sneppen, Kim

    2012-07-01

    The biological requirements for an ecosystem to develop and maintain species diversity are in general unknown. Here we consider a model ecosystem of sessile and mutually excluding organisms competing for space [Mathiesen Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.107.188101 107, 188101 (2011)]. Competition is controlled by an interaction network with fixed links chosen by a Bernoulli process. New species are introduced in the system at a predefined rate. In the limit of small introduction rates, the system becomes bistable and can undergo a phase transition from a state of low diversity to high diversity. We suggest that isolated patches of metapopulations formed by the collapse of cyclic relations are essential for the transition to the state of high diversity.

  4. Vegetation species diversity inside and outside exclosures in sagebrush, salt desert shrub, and aspen communities

    Treesearch

    W. A. Laycock; Dale Bartos

    1999-01-01

    Vegetation was sampled inside and outside eight exclosures in salt desert shrub and sagebrush vegetation types in Southwestern Wyoming and eight exclosures in aspen vegetation in southern Utah. Only species richness has been examined thus far. Five of the eight Wyoming exclosures had an average of 11% more plant species present outside the exclosure than inside.

  5. Importance of Soil Texture in Paleo-Vegetation Modeling Studies

    NASA Astrophysics Data System (ADS)

    Shellito, C. J.; Clifthorne, S.; Sloan, L. C.; Kueppers, L.

    2005-12-01

    The utility of a dynamic global vegetation model (DGVM) depends on the accuracy of the background climatology driving the model and the boundary conditions. In this study, we examine the sensitivity of the NCAR LSM-DGVM to one aspect of the boundary condition, the global soil texture. Soil texture is a critical factor influencing the availability of soil moisture. Available soil moisture will generally determine the dominant vegetation in a region, and, both soil moisture and vegetation will have important feedbacks on climate. Most paleoclimate modeling studies incorporate a globally uniform soil texture due to a lack of a global datasets regarding paleosol types. This becomes problematic when trying to address questions regarding potential changes in the global ecosystem due to a change in climate because the influence of soil texture on equilibrium vegetation in a DGVM experiment may be as large as other climatic forcing factors in a given region. In this study, we consider the effect of soil texture on the distribution of global vegetation in an Early Eocene DGVM study. We generate a global distribution of clay abundances using annual averaged temperatures and precipitation estimates from previous Eocene modeling studies. In all previous Eocene climate modeling studies, clay is specified at globally uniform value of 18%. In our new Eocene soil distribution, clay percentages vary from near zero to 80%. We incorporate the new soil scheme into the surface boundary conditions for a DGVM experiment. As model output demonstrates, the clay has a pronounced impact on soil moisture, which has a strong impact on the presence and abundance of plant functional types in the model.

  6. Effects of vegetation type on soil microbial community structure and catabolic diversity assessed by polyphasic methods in North China.

    PubMed

    Han, Xue-mei; Wang, Ren-qing; Liu, Jian; Wang, Meng-cheng; Zhou, Juan; Guo, Wei-hua

    2007-01-01

    Soil microbes play a major role in ecological processes and are closely associated with the aboveground plant community. In order to understand the effects of vegetation type on the characteristics of soil microbial communities, the soil microbial communities were assessed by plate counts, phospholipid fatty acid (PLFA) and Biolog microplate techniques in five plant communities, i.e., soybean field (SF), artificial turf (AT), artificial shrub (AS), natural shrub (NS), and maize field (MF) in Jinan, Shandong Province, North China. The results showed that plant diversity had little discernible effect on microbial biomass but a positive impact on the evenness of utilized substrates in Biolog microplate. Legumes could significantly enhance the number of cultural microorganisms, microbial biomass, and community catabolic diversity. Except for SF dominated by legumes, the biomass of fungi and the catabolic diversity of microbial community were higher in less disturbed soil beneath NS than in frequently disturbed soils beneath the other vegetation types. These results confirmed that high number of plant species, legumes, and natural vegetation types tend to support soil microbial communities with higher function. The present study also found a significant correlation between the number of cultured bacteria and catabolic diversity of the bacterial community. Different research methods led to varied results in this study. The combination of several approaches is recommended for accurately describing the characteristics of microbial communities in many respects.

  7. Vegetable parenting practices scale: Item response modeling analyses

    USDA-ARS?s Scientific Manuscript database

    Our objective was to evaluate the psychometric properties of a vegetable parenting practices scale using multidimensional polytomous item response modeling which enables assessing item fit to latent variables and the distributional characteristics of the items in comparison to the respondents. We al...

  8. Modeling the Atmospheric Dynamics within and Above Vegetation Layers

    Treesearch

    Warren E. Heilman; John Zasada

    2000-01-01

    A critical component of any silvicultural treatment is the creation of suitable microclimatic conditions for desired plant and animal species. One of the most useful tools for examining the microclimatic implications of different vegetation treatments is the use of atmospheric boundary-layer models that can simulate resulting micrometeorological conditions within and...

  9. A model for seed dispersion and vegetation growth

    NASA Astrophysics Data System (ADS)

    da Silva, Jaqueline Maria; Vieira Kritz, Maurício

    2016-08-01

    The study of processes associated with vegetation grow is very important to understand the dynamics of flooded ecosystems and their sustainable management. We present a cell-centered individual-based probabilistic model for the dynamics of tree-populations, that is further tailored towards the environmental conditions present in the Amazon floodplains.

  10. A comprehensive benchmarking system for evaluating global vegetation models

    NASA Astrophysics Data System (ADS)

    Kelley, D. I.; Prentice, I. C.; Harrison, S. P.; Wang, H.; Simard, M.; Fisher, J. B.; Willis, K. O.

    2013-05-01

    We present a benchmark system for global vegetation models. This system provides a quantitative evaluation of multiple simulated vegetation properties, including primary production; seasonal net ecosystem production; vegetation cover; composition and height; fire regime; and runoff. The benchmarks are derived from remotely sensed gridded datasets and site-based observations. The datasets allow comparisons of annual average conditions and seasonal and inter-annual variability, and they allow the impact of spatial and temporal biases in means and variability to be assessed separately. Specifically designed metrics quantify model performance for each process, and are compared to scores based on the temporal or spatial mean value of the observations and a "random" model produced by bootstrap resampling of the observations. The benchmark system is applied to three models: a simple light-use efficiency and water-balance model (the Simple Diagnostic Biosphere Model: SDBM), the Lund-Potsdam-Jena (LPJ) and Land Processes and eXchanges (LPX) dynamic global vegetation models (DGVMs). In general, the SDBM performs better than either of the DGVMs. It reproduces independent measurements of net primary production (NPP) but underestimates the amplitude of the observed CO2 seasonal cycle. The two DGVMs show little difference for most benchmarks (including the inter-annual variability in the growth rate and seasonal cycle of atmospheric CO2), but LPX represents burnt fraction demonstrably more accurately. Benchmarking also identified several weaknesses common to both DGVMs. The benchmarking system provides a quantitative approach for evaluating how adequately processes are represented in a model, identifying errors and biases, tracking improvements in performance through model development, and discriminating among models. Adoption of such a system would do much to improve confidence in terrestrial model predictions of climate change impacts and feedbacks.

  11. A comprehensive benchmarking system for evaluating global vegetation models

    NASA Astrophysics Data System (ADS)

    Kelley, D. I.; Prentice, I. Colin; Harrison, S. P.; Wang, H.; Simard, M.; Fisher, J. B.; Willis, K. O.

    2012-11-01

    We present a benchmark system for global vegetation models. This system provides a quantitative evaluation of multiple simulated vegetation properties, including primary production; seasonal net ecosystem production; vegetation cover, composition and height; fire regime; and runoff. The benchmarks are derived from remotely sensed gridded datasets and site-based observations. The datasets allow comparisons of annual average conditions and seasonal and inter-annual variability, and they allow the impact of spatial and temporal biases in means and variability to be assessed separately. Specifically designed metrics quantify model performance for each process, and are compared to scores based on the temporal or spatial mean value of the observations and a "random" model produced by bootstrap resampling of the observations. The benchmark system is applied to three models: a simple light-use efficiency and water-balance model (the Simple Diagnostic Biosphere Model: SDBM), and the Lund-Potsdam-Jena (LPJ) and Land Processes and eXchanges (LPX) dynamic global vegetation models (DGVMs). SDBM reproduces observed CO2 seasonal cycles, but its simulation of independent measurements of net primary production (NPP) is too high. The two DGVMs show little difference for most benchmarks (including the inter-annual variability in the growth rate and seasonal cycle of atmospheric CO2), but LPX represents burnt fraction demonstrably more accurately. Benchmarking also identified several weaknesses common to both DGVMs. The benchmarking system provides a quantitative approach for evaluating how adequately processes are represented in a model, identifying errors and biases, tracking improvements in performance through model development, and discriminating among models. Adoption of such a system would do much to improve confidence in terrestrial model predictions of climate change impacts and feedbacks.

  12. 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.

  13. Accounting for Vegetation Effects in Spatially Distributed Snowmelt Modeling

    NASA Astrophysics Data System (ADS)

    Garen, D. C.; Marks, D.

    2004-05-01

    The effects of vegetation on snowpack energy dynamics can be highly significant and must be taken into account when simulating snowmelt. This becomes challenging, however, for spatially distributed models covering large areas such as river basins. In this case, processes occurring at the scale of individual trees or bushes must be parameterized and upscaled to the size of the model's grid cells, which could range from 10 up to a few hundred meters. An application of a spatially distributed energy balance snowmelt model to the Boise River basin in Idaho, USA has required the development of algorithms to account for the effects of vegetation (especially forest) on the climate input data to the model. This particularly affects the solar and thermal radiation input to the snowpack, including not only the direct effects of the vegetation but also the effect of vegetation debris on the snow albedo. Vegetation effects on vertical profiles of wind speed and temperature could not be considered due to limited measurements, and only a crude estimate of wind speed differences between forested and nonforested grid cells was used. The simulated snow fields were verified using point snow water equivalent and snow depth data as well as satellite images of snow covered area. Although good results were obtained in these comparisons, each of these methods has limitations, in that point measurements are not necessarily representative of a grid cell, and satellite images have a coarse resolution and cannot detect snow under trees. Another test was to use the simulated snowmelt fields as input to a spatially distributed water balance and streamflow simulation model, which indicated that the volume and timing of snowmelt input to the basin were accurately represented. A limitation of the modeling method used is that the models are run independently in sequence, the output of one being stored and becoming the input of the next. This means that there is no opportunity for feedbacks between

  14. Potential climatic impacts of vegetation change: A regional modeling study

    USGS Publications Warehouse

    Copeland, J.H.; Pielke, R.A.; Kittel, T.G.F.

    1996-01-01

    The human species has been modifying the landscape long before the development of modern agrarian techniques. Much of the land area of the conterminous United States is currently used for agricultural production. In certain regions this change in vegetative cover from its natural state may have led to local climatic change. A regional climate version of the Colorado State University Regional Atmospheric Modeling System was used to assess the impact of a natural versus current vegetation distribution on the weather and climate of July 1989. The results indicate that coherent regions of substantial changes, of both positive and negative sign, in screen height temperature, humidity, wind speed, and precipitation are a possible consequence of land use change throughout the United States. The simulated changes in the screen height quantities were closely related to changes in the vegetation parameters of albedo, roughness length, leaf area index, and fractional coverage. Copyright 1996 by the American Geophysical Union.

  15. improved vegetation phenology in the JULES land-surface model

    NASA Astrophysics Data System (ADS)

    Los, S. O.

    2013-12-01

    Sietse Los, Steven Hancock, Peter North, Jose Gomez-Dans Introduction: Land-surface properties such as albedo, soil moisture and vegetation biophysical parameters affect water, energy and carbon fluxes from the land to the atmosphere an this can alter weather patterns. Here we use globally consistent satellite observations to improve modelling of the vegetation seasonal cycle in the JULES land-surface model (LSM) to better represent these fluxes. JULES model: The JULES LSM is the land surface component of the suite of UK MetOffice general circulation models. JULES is used both in operational weather forecasting and for simulations of future climate. Within JULES, seasonal changes in surface albedo are controlled by snow (not covered here) and vegetation dynamics (phenology). Vegetation phenology is controlled by temperature and water availability, with timings and rates set by a number of trigger thresholds and leaf growth/death rates. Satellite data: The ability of JULES to represent vegetation, in terms of its seasonal cycle as well as the interannual variation, was tested on normalised difference vegetation index (NDVI = (near-infrared - red) / (near-infrared + red)) data. JULES uses a 1D radiative transfer model to predict hemispheric surface albedo for a given leaf area whilst satellites measure reflectance from a single view direction and this may not match the hemispheric albedo. To test this, JULES predictions were compared to the FLIGHT (a 3D radiative transfer model) simulations for different view directions. This revealed that either NDVI profiles need to be normalised to allow a direct comparison (as done here) or else the JULES 1D model must be replaced by a full 3D radiative transfer model, which is computationally expensive. Experiments: The original phenology module in JULES was optimised against NDVI observations using a Monte-Carlo Markov chain method. This optimisation was unsuccessful; and we therefore concluded that the JULES phenology cannot

  16. Discrete random media techniques for microwave modeling of vegetated terrain

    NASA Technical Reports Server (NTRS)

    Lang, Roger H.

    1991-01-01

    Microwave remote sensing models of vegetated terrain are investigated. The problem is to determine canopy characteristics such as biomass, canopy height, and the moisture of the underlying soil. The report describes a discrete scatter model which has been employed to model backscatter in the active (radar) case and to model brightness temperature in the passive (radiometric) case. The acquisition of ground truth data is discussed, as well as the comparison of theory and experiment. The overall conclusion of the work has been that the discrete scatter model in conjunction with efficient scatter algorithms and the distorted Born approximation is a most appropriate methodology to use for modeling purposes in the microwave region.

  17. Statistical Models for Inferring Vegetation Composition from Fossil Pollen

    NASA Astrophysics Data System (ADS)

    Paciorek, C.; McLachlan, J. S.; Shang, Z.

    2011-12-01

    Fossil pollen provide information about vegetation composition that can be used to help understand how vegetation has changed over the past. However, these data have not traditionally been analyzed in a way that allows for statistical inference about spatio-temporal patterns and trends. We build a Bayesian hierarchical model called STEPPS (Spatio-Temporal Empirical Prediction from Pollen in Sediments) that predicts forest composition in southern New England, USA, over the last two millenia based on fossil pollen. The critical relationships between abundances of tree taxa in the pollen record and abundances in actual vegetation are estimated using modern (Forest Inventory Analysis) data and (witness tree) data from colonial records. This gives us two time points at which both pollen and direct vegetation data are available. Based on these relationships, and incorporating our uncertainty about them, we predict forest composition using fossil pollen. We estimate the spatial distribution and relative abundances of tree species and draw inference about how these patterns have changed over time. Finally, we describe ongoing work to extend the modeling to the upper Midwest of the U.S., including an approach to infer tree density and thereby estimate the prairie-forest boundary in Minnesota and Wisconsin. This work is part of the PalEON project, which brings together a team of ecosystem modelers, paleoecologists, and statisticians with the goal of reconstructing vegetation responses to climate during the last two millenia in the northeastern and midwestern United States. The estimates from the statistical modeling will be used to assess and calibrate ecosystem models that are used to project ecological changes in response to global change.

  18. Wave attenuation by a model of vegetation in a flume

    NASA Astrophysics Data System (ADS)

    Chastel, Thibault; Durand, Nathalie

    2017-04-01

    The quantification of wave attenuation by vegetation is important for understanding shore protection and modeling coastal hydrodynamics. We investigate experimentally how different devices can modify the dynamics of irregular waves propagated in a flume. In particular we focus on a model of vegetation represented by flexible propylene stems with a modulus of elasticity E = 1200 MPa, a height l = 0.28 m and a diameter 2a = 0.025 m. The vegetation-like surface density is N = 720 stems/m2. The flume is 80 m long, 1.5 m wide and 1.2 m deep with 20 capacitance-type wave probes distributed over 20 meters. A flap type paddle generated waves using the JONSWAP spectrum. Experiments are for 500 wave cycles for water depth wd varying between 0.30 and 0.83 m and several significant wave heights Hs and wave periods Tp. We measure the wave height attenuation compared to flat-bed experiments and we apply a spectral analysis for post-processing. The loss of energy due to the stems is quantified and depends strongly on wave characteristics and geometrical parameters, in particular on the ratio l/wd. From these experiments we can estimate a drag coefficient CD by using a model of wave energy dissipation developed by Méndez and Losada (2004) which takes into account both wave and vegetation parameters.

  19. Why we need better predictive models of vegetation phenology

    NASA Astrophysics Data System (ADS)

    Richardson, Andrew; Migliavacca, Mirco; Keenan, Trevor

    2014-05-01

    Vegetation phenology is strongly affected by climate change, with warmer temperatures causing earlier spring onset and delayed autumn senescence in most temperate and boreal ecosystems. In arid regions where phenology is driven by the seasonality of soil water availability, shifts in the timing, intensity, and total amount of precipitation are, likewise, affecting the seasonality of vegetation activity. Changes in the duration of the growing season have important implications for ecosystem productivity and uptake of CO2 from the atmosphere, as well as site water balance and runoff, microclimate, ecological interactions within and across trophic levels, and numerous feedbacks to the climate system associated with the surface energy budget. However, an outstanding challenge is that existing phenology sub-models used in ecosystem, land surface, and terrestrial biosphere models fail to adequately represent the seasonality, or sensitivity to environmental drivers, of vegetation phenology. This has two implications. First, these models are therefore likely to perform poorly under future climate scenarios. Second, the seasonality of important ecological processes and interactions, as well as biosphere-atmosphere feedbacks, is likely to be misrepresented as a result. Using data from several recent analyses, and focusing on temperate and boreal ecosystems, we will review current challenges associated with modeling vegetation phenology. We will discuss uncertainties associated with phenology model structure, model parameters, and driver sensitivity (forcing, chilling, and photoperiod). We will show why being able to extrapolate and generalize models (and model parameterization) is essential. We will consider added challenges associated with trying to model autumn phenology. Finally, we will use canopy photosynthesis and uptake of CO2 as an example of why improved understanding of the "rhythm of the seasons" is critically important.

  20. Modeling the land surface boundary in climate models as a composite of independent vegetation stands

    NASA Technical Reports Server (NTRS)

    Koster, Randal D.; Suarez, Max J.

    1992-01-01

    An efficient strategy for modeling the land surface boundary in general circulation models (GCMs) is presented which accounts for the effects of vegetation on surface energy fluxes and allows for an arbitrary number of vegetation types to coexist in a grid square. The GCM grid square is depicted as a 'mosaic' of vegetation 'tiles', with each tile consisting of a single vegetation type. The energy balance equation for each tile follows closely that of a single vegetation version of the simple biosphere (SiB) model of Sellers et al. (1986) but is simplified enough to be written in Penman-Monteith form. Each tile in the square is coupled independently to the GCM atmosphere, and tiles affect each other only through the atmosphere. This coupling strategy differs conceptually from that of models such as SiB that assume a homogeneous mixture of vegetation types within a GCM grid square. A quantitative comparison of the two strategies is presented.

  1. A Model for Cultural Diversity Training.

    ERIC Educational Resources Information Center

    Sue, Derald Wing

    1991-01-01

    Presents model for incorporating cultural diversity in organizations, based on 3 X 3 X 3 matrix, which analyzes organization's functional focus (recruitment, retention, promotion), barriers (differences, discrimination, systemic factors), and cross-cultural competencies (beliefs/attitudes, knowledge, skills). Although originally developed for…

  2. Evaluating Hyperspectral Vegetation Indices for Leaf Area Index Estimation of Oryza sativa L. at Diverse Phenological Stages

    PubMed Central

    Din, Mairaj; Zheng, Wen; Rashid, Muhammad; Wang, Shanqin; Shi, Zhihua

    2017-01-01

    Hyperspectral reflectance derived vegetation indices (VIs) are used for non-destructive leaf area index (LAI) monitoring for precise and efficient N nutrition management. This study tested the hypothesis that there is potential for using various hyperspectral VIs for estimating LAI at different growth stages of rice under varying N rates. Hyperspectral reflectance and crop canopy LAI measurements were carried out over 2 years (2015 and 2016) in Meichuan, Hubei, China. Different N fertilization, 0, 45, 82, 127, 165, 210, 247, and 292 kg ha-1, were applied to generate various scales of VIs and LAI values. Regression models were used to perform quantitative analyses between spectral VIs and LAI measured under different phenological stages. In addition, the coefficient of determination and RMSE were employed to evaluate these models. Among the nine VIs, the ratio vegetation index, normalized difference vegetation index (NDVI), modified soil-adjusted vegetation index (MSAVI), modified triangular vegetation index (MTVI2) and exhibited strong and significant relationships with the LAI estimation at different phenological stages. The enhanced vegetation index performed moderately. However, the green normalized vegetation index and blue normalized vegetation index confirmed that there is potential for crop LAI estimation at early phenological stages; the soil-adjusted vegetation index and optimized soil-adjusted vegetation index were more related to the soil optical properties, which were predicted to be the least accurate for LAI estimation. The noise equivalent accounted for the sensitivity of the VIs and MSAVI, MTVI2, and NDVI for the LAI estimation at phenological stages. The results note that LAI at different crop phenological stages has a significant influence on the potential of hyperspectral derived VIs under different N management practices. PMID:28588596

  3. Linking Vegetation Structure and Spider Diversity in Riparian and Adjacent Habitats in Two Rivers of Central Argentina: An Analysis at Two Conceptual Levels.

    PubMed

    Griotti, Mariana; Muñoz-Escobar, Christian; Ferretti, Nelson E

    2017-08-01

    The link between vegetation structure and spider diversity has been well explored in the literature. However, few studies have compared spider diversity and its response to vegetation at two conceptual levels: assemblage (species diversity) and ensemble (guild diversity). Because of this, we studied spider diversity in riparian and adjacent habitats of a river system from the Chacoan subregion in central Argentina and evaluated their linkage with vegetation structure at these two levels. To assess vegetation structure, we measured plant species richness and vegetation cover in the herb and shrub - tree layers. We collected spiders for over 6 months by using vacuum netting, sweep netting and pitfall traps. We collected 3,808 spiders belonging to 119 morphospecies, 24 families and 9 guilds. At spider assemblage level, SIMPROF analysis showed significant differences among studied habitats. At spider ensemble level, nevertheless, we found no significant differences among habitats. Concerning the linkage with vegetation structure, BIOENV test showed that spider diversity at either assemblage or ensemble level was not significantly correlated with the vegetation variables assessed. Our results indicated that spider diversity was not affected by vegetation structure. Hence, even though we found a pattern in spider assemblages among habitats, this could not be attributed to vegetation structure. In this study, we show that analyzing a community at two conceptual levels will be useful for recognizing different responses of spider communities to vegetation structure in diverse habitat types. © 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.

  4. Fine and Coarse-Scale Patterns of Vegetation Diversity on Reclaimed Surface Mine-land Over a 40-Year Chronosequence.

    PubMed

    Bohrer, Stefanie L; Limb, Ryan F; Daigh, Aaron L; Volk, Jay M; Wick, Abbey F

    2017-03-01

    Rangelands are described as heterogeneous, due to patterning in species assemblages and productivity that arise from species dispersal and interactions with environmental gradients and disturbances across multiple scales. The objectives of rangeland reclamation are typically vegetation establishment, plant community productivity, and soil stability. However, while fine-scale diversity is often promoted through species-rich seed mixes, landscape heterogeneity and coarse-scale diversity are largely overlooked. Our objectives were to evaluate fine and coarse-scale vegetation patterns across a 40-year reclamation chronosequence on reclaimed surface coalmine lands. We hypothesized that both α-diversity and β-diversity would increase and community patch size and species dissimilarity to reference sites would decrease on independent sites over 40 years. Plant communities were surveyed on 19 post-coalmine reclaimed sites and four intact native reference sites in central North Dakota mixed-grass prairie. Our results showed no differences in α or β-diversity and plant community patch size over the 40-year chronosequence. However, both α-diversity and β-diversity on reclaimed sites was similar to reference sites. Native species establishment was limited due to the presence of non-native species such as Kentucky bluegrass (Poa pratensis) on both the reclaimed and reference sites. Species composition was different between reclaimed and reference sites and community dissimilarity increased on reclaimed sites over the 40-year chronosequence. Plant communities resulting from reclamation followed non-equilibrium succession, even with consistent seeds mixes established across all reclaimed years. This suggests post-reclamation management strategies influence species composition outcomes and land management strategies applied uniformly may not increase landscape-level diversity.

  5. Fine and Coarse-Scale Patterns of Vegetation Diversity on Reclaimed Surface Mine-land Over a 40-Year Chronosequence

    NASA Astrophysics Data System (ADS)

    Bohrer, Stefanie L.; Limb, Ryan F.; Daigh, Aaron L.; Volk, Jay M.; Wick, Abbey F.

    2017-03-01

    Rangelands are described as heterogeneous, due to patterning in species assemblages and productivity that arise from species dispersal and interactions with environmental gradients and disturbances across multiple scales. The objectives of rangeland reclamation are typically vegetation establishment, plant community productivity, and soil stability. However, while fine-scale diversity is often promoted through species-rich seed mixes, landscape heterogeneity and coarse-scale diversity are largely overlooked. Our objectives were to evaluate fine and coarse-scale vegetation patterns across a 40-year reclamation chronosequence on reclaimed surface coalmine lands. We hypothesized that both α-diversity and β-diversity would increase and community patch size and species dissimilarity to reference sites would decrease on independent sites over 40 years. Plant communities were surveyed on 19 post-coalmine reclaimed sites and four intact native reference sites in central North Dakota mixed-grass prairie. Our results showed no differences in α or β-diversity and plant community patch size over the 40-year chronosequence. However, both α-diversity and β-diversity on reclaimed sites was similar to reference sites. Native species establishment was limited due to the presence of non-native species such as Kentucky bluegrass ( Poa pratensis) on both the reclaimed and reference sites. Species composition was different between reclaimed and reference sites and community dissimilarity increased on reclaimed sites over the 40-year chronosequence. Plant communities resulting from reclamation followed non-equilibrium succession, even with consistent seeds mixes established across all reclaimed years. This suggests post-reclamation management strategies influence species composition outcomes and land management strategies applied uniformly may not increase landscape-level diversity.

  6. Microwave model prediction and verifications for vegetated terrain

    NASA Technical Reports Server (NTRS)

    Fung, A. K.

    1985-01-01

    To understand the scattering properties of a deciduous and a coniferous type vegetation scattering models were developed assuming either a disc type leaf or a needle type leaf. The major effort is to calculate the corresponding scattering phase functions and then each of the functions is used in a radiative transfer formulation to compute the scattering intensity and consequently the scattering coefficient. The radiative transfer formulation takes into account the irregular ground surface by including the rough soil surface in the boundary condition. Thus, the scattering model accounts for volume scattering inside the vegetation layer, the surface scattering from the ground and the interaction between scattering from the soil surface and the vegetation volume. The contribution to backscattering by each of the three scattering mechanisms is illustrated along with the effects of each layer or surface parameter. The major difference between the two types of vegetation is that when the incident wavelength is comparable to the size of the leaf there is a peak appearing in the mid angular region of the backscattering curve for the disc type leaf whereas it is a dip in the same region for a needle type leaf.

  7. A Novel Approach to Modeling Vegetation Distributions and Analyzing Vegetation Sensitivity Through Trait-Climate Relationships In China

    NASA Astrophysics Data System (ADS)

    Yang, Y.; Peng, C.; Zhu, Q.; Wang, H.

    2015-12-01

    There is increasing evidence that current DGVMs have suffered insufficient realism and hard to improve, particularly because they are built on plant functional type (PFT)-climate schemes. It is urgent to develop new approaches, like plant trait-based methods (FTs), to replace of PFT schemes when predicting the distribution of vegetation and investigating the vegetation sensitivity. In this research, we proposed a novel approach to modeling vegetation distributions and analyzing the vegetation sensitivity through trait-climate relationship in China. First, we aggregated data on three key FTs, including leaf mass per area (LMA), area-based leaf nitrogen (Narea), and mass-based leaf nitrogen (Nmass), from the available literatures. In addition, one structural trait of plant communities, leaf area index (LAI), was extracted from MODIS products across China. Second, we derived and developed trait-climate relationships and used different trait combinations in a Gaussian Mixture Model (GMM) to model vegetation distribution. Finally, the GMM trained by the LMA-Nmass-LAI combination was applied to investigate the climate sensitivity of vegetation. The results demonstrated the following: (1) all four traits captured well the relationships between climate variables and traits, as well as effectively predicted vegetation distribution and helped analyzing environmental sensitivity; (2) the LMA-Nmass-LAI combination yielded an accuracy of 72.05% for simulating vegetation distribution, providing more detailed parameter information regarding community structures and ecosystem function, and was therefore selected for training GMMs; and (3) a sensitivity analysis indicated that increasing temperatures shifted the boundaries of most vegetation northward and westward. Because the forests in these regions are well adapted to growth under rainy conditions, increasing precipitation is predicted to expand the boundaries of forests compared with the baseline vegetation distribution

  8. 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

  9. 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

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

    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.

  11. 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

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

    PubMed

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

    2016-04-07

    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.

  13. Significant inconsistency of vegetation carbon density in CMIP5 Earth system models against observational data: Vegetation Carbon Density in ESMs

    DOE PAGES

    Song, Xia; Hoffman, Forrest M.; Iversen, Colleen M.; ...

    2017-09-09

    Earth system models (ESMs) have been widely used for projecting global vegetation carbon dynamics, yet how well ESMs performed for simulating vegetation carbon density remains untested. Here we have compiled observational data of vegetation carbon density from literature and existing data sets to evaluate nine ESMs at site, biome, latitude, and global scales. Three variables—root (including fine and coarse roots), total vegetation carbon density, and the root:total vegetation carbon ratios (R/T ratios), were chosen for ESM evaluation. ESM models performed well in simulating the spatial distribution of carbon densities in root (r = 0.71) and total vegetation (r = 0.62).more » However, ESM models had significant biases in simulating absolute carbon densities in root and total vegetation biomass across the majority of land ecosystems, especially in tropical and arctic ecosystems. Particularly, ESMs significantly overestimated carbon density in root (183%) and total vegetation biomass (167%) in climate zones of 10°S–10°N. Substantial discrepancies between modeled and observed R/T ratios were found: the R/T ratios from ESMs were relatively constant, approximately 0.2 across all ecosystems, along latitudinal gradients, and in tropic, temperate, and arctic climatic zones, which was significantly different from the observed large variations in the R/T ratios (0.1–0.8). There were substantial inconsistencies between ESM-derived carbon density in root and total vegetation biomass and the R/T ratio at multiple scales, indicating urgent needs for model improvements on carbon allocation algorithms and more intensive field campaigns targeting carbon density in all key vegetation components.« less

  14. MC1: a dynamic vegetation model for estimating the distribution of vegetation and associated carbon, nutrients, and water—technical documentation. Version 1.0.

    Treesearch

    Dominique Bachelet; James M. Lenihan; Christopher Daly; Ronald P. Neilson; Dennis S. Ojima; William J. Parton

    2001-01-01

    Assessments of vegetation response to climate change have generally been made only by equilibrium vegetation models that predict vegetation composition under steady-state conditions. These models do not simulate either ecosystem biogeochemical processes or changes in ecosystem structure that may, in turn, act as feedbacks in determining the dynamics of vegetation...

  15. Genetic Diversity and Antibiotic Resistance Patterns of Staphylococcus Aureus Isolated from Leaf Vegetables in Korea.

    PubMed

    Hong, Jisoo; Kim, Yangkyun; Kim, Jonguk; Heu, Sunggi; Kim, Se-ri; Kim, Kwang-Pyo; Roh, Eunjung

    2015-07-01

    Staphylococcus aureus is an important foodborne pathogen on global basis. The current study investigated the genetic patterns in S. aureus isolates from leaf vegetables (n = 53). Additional isolates from livestock (n = 31) and humans (n = 27) were compared with the leaf vegetable isolates. Genes associated with toxins, antibiotic resistance, and pulsed-field gel electrophoresis (PFGE) patterns were analyzed. At least 1 enterotoxin-encoding gene (sea, seb, sec, sed, and see) was detected in 11 of 53 (20.75%) leaf vegetable isolates. When the agr (accessory gene regulator) grouping was analyzed, agr II was the major group, whereas agr IV was not present in leaf vegetable isolates. All S. aureus isolates from leaf vegetables were resistant to more than one of the antibiotics tested. Nineteen of 53 (35.85%) isolates from leaf vegetables exhibited multidrug-resistance, and 11 of these were MRSA (methicillin-resistant S. aureus). A dendrogram displaying the composite types of S. aureus isolates from 3 origins was generated based on the combination of the toxin genes, agr genes, antibiotic resistance, and PFGE patterns. The isolates could be clustered into 8 major composite types. The genetic patterns of S. aureus isolates from leaf vegetables and humans were similar, whereas those from livestock had unique patterns. This suggests some S. aureus isolates from leaf vegetables to be of human origin.

  16. Model-data integration to improve the LPJmL dynamic global vegetation model

    NASA Astrophysics Data System (ADS)

    Forkel, Matthias; Thonicke, Kirsten; Schaphoff, Sibyll; Thurner, Martin; von Bloh, Werner; Dorigo, Wouter; Carvalhais, Nuno

    2017-04-01

    Dynamic global vegetation models show large uncertainties regarding the development of the land carbon balance under future climate change conditions. This uncertainty is partly caused by differences in how vegetation carbon turnover is represented in global vegetation models. Model-data integration approaches might help to systematically assess and improve model performances and thus to potentially reduce the uncertainty in terrestrial vegetation responses under future climate change. Here we present several applications of model-data integration with the LPJmL (Lund-Potsdam-Jena managed Lands) dynamic global vegetation model to systematically improve the representation of processes or to estimate model parameters. In a first application, we used global satellite-derived datasets of FAPAR (fraction of absorbed photosynthetic activity), albedo and gross primary production to estimate phenology- and productivity-related model parameters using a genetic optimization algorithm. Thereby we identified major limitations of the phenology module and implemented an alternative empirical phenology model. The new phenology module and optimized model parameters resulted in a better performance of LPJmL in representing global spatial patterns of biomass, tree cover, and the temporal dynamic of atmospheric CO2. Therefore, we used in a second application additionally global datasets of biomass and land cover to estimate model parameters that control vegetation establishment and mortality. The results demonstrate the ability to improve simulations of vegetation dynamics but also highlight the need to improve the representation of mortality processes in dynamic global vegetation models. In a third application, we used multiple site-level observations of ecosystem carbon and water exchange, biomass and soil organic carbon to jointly estimate various model parameters that control ecosystem dynamics. This exercise demonstrates the strong role of individual data streams on the

  17. Pathogen Propagation Model with Superinfection in Vegetatively Propagated Plants on Lattice Space

    PubMed Central

    Sakai, Yuma; Takada, Takenori

    2016-01-01

    Many clonal plants have two reproductive patterns, seed propagation and vegetative propagation. By vegetative propagation, plants reproduce the genetically identical offspring with a low mortality, because resources are supplied from the other individuals through interconnected ramets at vegetative-propagated offspring. However, the ramets transport not only resources but also systemic pathogen. Pathogens evolve to establish and spread widely within the plant population. The superinfection, which is defined as the ability that an established pathogen spreads widely by infecting to already-infected individuals with other strains of a pathogen, is important to the evolution of pathogens. We examine the dynamics of plant reproduction and pathogen propagation considering spatial structure and the effect of superinfection on genetic diversity of pathogen by analysis of several models, 1-strain and multiple-strain models, on two-dimensional square lattice. In the analysis of 1-strain model, we derive equilibrium value by mean-field approximation and pair approximation, and its local stability by Routh-Hurwitz stability criterion. In the multiple-strain models, we analyze the dynamics by numerical simulation of mean-field approximation, pair approximation and Monte Carlo simulation. Through the analyses, we show the effect of parameter values to dynamics of models, such as transition of dominant strain of pathogen, competition between plants and pathogens and density of individuals. As a result, (i) The strain with intermediate cost becomes dominant when both superinfection rate and growth rate are low. (ii) The competition between plants and pathogens occurs in the phase of coexistence of various strains by pair approximation and Monte Carlo simulation. (iii) Too high growth rate leads to the decrease of plant population in all models. (iv) Pathogens are easy to maintain their genetic diversity with low superinfection rate. However, if they do not superinfect, the

  18. Measuring and Modeling of the Dielectric Properties and Attenuation of Vegetation

    NASA Technical Reports Server (NTRS)

    Ulaby, F. T.

    1984-01-01

    The dielectric properties and attenuation of vegetation was measured and modeled. The purpose was to: (1) measure the microwave dielectric properties of vegetation material as a function of moisture content and microwave frequency; (2) develop dielectric mixing models for the vegetation-water mixture; (3) develop a model for the loss factor of a vegetation canopy; (4) relate the results of (1) and (2) to (3); and (5) test the model in (3) against direct canopy transmission measurements.

  19. Geomorphic process and vegetation diversity in the active riverbed and the floodplain in the Kamikochi valley, central Japan

    NASA Astrophysics Data System (ADS)

    Shimazu, H.

    2012-04-01

    The Kamikochi valley is located in a mountainous area in central Japan. The R. Azusa in this valley is a braided river with floodplains. Dense riparian forests cover the floodplains and fragmented small pioneer plant patches and isolated old pioneer trees are distributed in the active riverbed. This study aims to discuss the relationships between geomorphic processes of the river and vegetation diversity. Yearly mapping of the riverbed micro-landforms revealed that channel migrations and landform changes in the active riverbed occurs once every one or several years during a bankfull flood in the rainy season. Germination ages of riparian trees using a dendrochronological technique, their established layers and landform structure were examined to reconstruct floodplain dynamics. Major channel migrations destroyed the riparian forest repeatedly and the recent event occurred about 100 years ago. This caused a longitudinal zonal structure of the riparian forest vegetation, elm-fir forest, mature pioneer forest and young pioneer forests. The young pioneer forest is located alongside the present riverbed. The mature pioneer forest lies between the older elm-fir forests. The pioneer plants germinated simultaneously on the abandoned channel after channel migration. These trees became the mature pioneer forest. Ditches and lobes including boulders are found in the floodplain. The ditches extend parallel to the direction of the present and former channels. The lobes are distributed alongside them. Younger trees under the canopy grow on the lobes in the inner part of the floodplain. These young trees and lobes show that dominant sedimentation process in the floodplain is not lateral flooding, but longitudinal flooding. Sediments from the present channel flew downward through the ditches and were overflowed on the floodplain. This process destroyed the vegetation in and alongside the ditches causing vegetation diversity in the inner part of the riparian forest. Several species

  20. Modeling of microwave scattering from vegetated covered terrain

    NASA Technical Reports Server (NTRS)

    Lang, R. H.

    1982-01-01

    General formulation of resonant backscattering from vegetation, mean field and Green's function in three media, and electromagnetic backscattering coefficients from a layer of vegetation are discussed.

  1. The Hydrological Regimes Brought by the Three Gorges Project Affected Riparian Vegetation Distribution and Diversity in 2009 and 2010

    NASA Astrophysics Data System (ADS)

    Miao, Ling-Feng; Liu, Wei-Wei; Yang, Fan

    2017-01-01

    Post-dam riparian vegetations affected by the new hydrological regimes in the Three Gorges Reservoir (TGR) were investigated in 2009 and 2010, respectively. The investigation in 2009 showed that about 231 vascular plant species belonging to 169 genera of 61 families were distributed in the water-level-fluctuation zone (WLFZ) of the (TGR). Three vegetation types, including Chuanjiang, Gorge, and other vegetation types, were classified efficiently via cluster analysis. Alpha diversity analysis indicated that species richness gradually decreased with decreasing elevation. Beta diversity analysis indicated that high environment heterogeneity was existed between the lower section and the other two sections, and environment homogeneity was also existed between middle section and upper section. Using the analysis of the field growth in the 2009 and 2010 field surveys as bases, we proposed a list of perennial herb species and woody species that may potentially occurred in the WLFZ of the TGR. In addition, we predicted plant community structural changes in the different altitude sections of WLFZ in the future.

  2. Modeling Hydrologic and Vegetation Responses in Freshwater Wetlands

    NASA Astrophysics Data System (ADS)

    Chui, Ting Fong May; Low, Swee Yang; Liong, Shie-Yui

    2010-05-01

    Wetlands constitute 6 - 7 % of the Earth's land surface and provide various critical ecosystem services such as purifying the air and water, mitigating floods and droughts, and supporting wildlife habitats. Despite the importance of wetlands, they are under threat of degradation by human-induced land use changes and climate change. Even if the value of wetlands is recognized, they are often not managed properly or restored successfully due to an inadequate understanding of the ecosystems and their responses to management scenarios. A better understanding of the main components of wetlands, namely the interdependent hydrologic and vegetation systems, and the sensitivity of their responses to engineering works and climate change, is crucial for the preservation of wetlands. To assess these potential impacts, a model is developed in this study for characterizing the coupled dynamics between soil moisture and plant biomass in wetland habitats. The hydrology component of the model is based on the Richards' equation and simulates spatially-varying groundwater movement and provides information on soil moisture at different depths. The plant growth component of the model is described through an equation of the Lotka-Volterra type modified for plant growth dynamics and is adapted from published literature. The two components are coupled via transpiration and ecosystem carrying capacity for plants. Transpiration is modeled for both unsaturated and saturated zones, while the carrying capacity describes limiting oxygen and subsequent nutrient availability in the soil column as a function of water table depth. Vegetation is represented by two species characteristic of mudflat herbaceous plants ranging from facultative wetland to upland plants. The model is first evaluated using a simplified domain and the hydrological information available in the RG2 site of the Everglades wetlands region. The modeled water table fluctuations in general are comparable to field data collected on

  3. Understanding the behavioral linkages needed for designing effective interventions to increase fruit and vegetable intake in diverse populations

    USDA-ARS?s Scientific Manuscript database

    The design of interventions to increase fruit and vegetable consumption in a population (e.g. all men, all elementary school students) requires an underlying model that organizes the relevant literatures and provides an audience. The mediating-moderating variable model is a statistical analysis tech...

  4. Regression based modeling of vegetation and climate variables for the Amazon rainforests

    NASA Astrophysics Data System (ADS)

    Kodali, A.; Khandelwal, A.; Ganguly, S.; Bongard, J.; Das, K.

    2015-12-01

    Both short-term (weather) and long-term (climate) variations in the atmosphere directly impact various ecosystems on earth. Forest ecosystems, especially tropical forests, are crucial as they are the largest reserves of terrestrial carbon sink. For example, the Amazon forests are a critical component of global carbon cycle storing about 100 billion tons of carbon in its woody biomass. There is a growing concern that these forests could succumb to precipitation reduction in a progressively warming climate, leading to release of significant amount of carbon in the atmosphere. Therefore, there is a need to accurately quantify the dependence of vegetation growth on different climate variables and obtain better estimates of drought-induced changes to atmospheric CO2. The availability of globally consistent climate and earth observation datasets have allowed global scale monitoring of various climate and vegetation variables such as precipitation, radiation, surface greenness, etc. Using these diverse datasets, we aim to quantify the magnitude and extent of ecosystem exposure, sensitivity and resilience to droughts in forests. The Amazon rainforests have undergone severe droughts twice in last decade (2005 and 2010), which makes them an ideal candidate for the regional scale analysis. Current studies on vegetation and climate relationships have mostly explored linear dependence due to computational and domain knowledge constraints. We explore a modeling technique called symbolic regression based on evolutionary computation that allows discovery of the dependency structure without any prior assumptions. In symbolic regression the population of possible solutions is defined via trees structures. Each tree represents a mathematical expression that includes pre-defined functions (mathematical operators) and terminal sets (independent variables from data). Selection of these sets is critical to computational efficiency and model accuracy. In this work we investigate

  5. Wild fire effects on floristic diversity in three thermo-Mediterranean vegetation types in a small islet of eastern Aegean sea

    NASA Astrophysics Data System (ADS)

    Abraham, Eleni; Kyriazopoulos, Apostolos; Korakis, George; Parissi, Zoi; Chouvardas, Dimitrios

    2014-05-01

    Sclerophyllus scrub formations, the main vegetation type in many islands of the Aegean area, are characterized by their high biodiversity. Dominant shrub species of sclerophyllus formations are well adapted to dry season conditions by various anatomical and physiological mechanisms. As a result, their biomass acts as very flammable fine fuel, and consequently wild fires are very common in these ecosystems. Wildfire effects on vegetation and biodiversity in the Mediterranean basin have been studied and the results are diverse depending mainly on vegetation type and frequency of fire. The aim of this study was to evaluate the effects of wildfire on floristic diversity and species composition in three thermo-Mediterranean vegetation types 1) Sacropoterium spinosum phrygana, 2) low formations of Cistus creticus and 3) low formations of Cistus creticus in abandoned terraces. The research was conducted in Enoussa islet, which is located northeastern of Chios Island, in May 2013 (one year after the fire). Vegetation sampling was performed along five transects placed in recently burned and in adjacent unburned sites of each vegetation type. The plant cover and the floristic composition were measured, while diversity, evenness and dominance indices were determined for the vegetation data. Vegetation cover and the floristic diversity were significant lower and higher respectively in burned areas in comparison to the unburned. The woody species followed by the annual grasses and the annual forbs dominated in both burned and unburned areas. However, the woody species were significantly decreased in the burned areas in all vegetation types, while the annual grasses only in the burned areas of Sacropoterium spinosum phrygana and Cistus creticus in abandoned terraces. Inversely, the annual forbs significantly increased in the burned sites of Cistus creticus formations. The highest value of Morisita-Horn Index of similarity between burned and unburned sites (beta diversity) was

  6. Waste heaps left by historical Zn-Pb ore mining are hotspots of species diversity of beech forest understory vegetation.

    PubMed

    Woch, Marcin W; Stefanowicz, Anna M; Stanek, Małgorzata

    2017-12-01

    Metalliferous mining and smelting industries are associated with very high levels of heavy metal(loid) contamination of the environment. Heavy metals have been proved to significantly influence the species diversity and composition of grassland communities, but little is known on their effects on forest understory vegetation. Therefore, the aim of this study was to investigate the effects of the presence of small heaps of waste rock left by historical Zn-Pb ore mining on understory vegetation. The heaps are scattered over vast areas of beech forests in southern Poland. Three types of study plots were established: (1) on waste heaps themselves, (2) in their vicinity (5-10m from the foot of the heaps, with no waste rock but potentially influenced by the heaps through drainage water), and (3) at least 100m from the foot of the heaps (pseudo-control). In all plots vegetation parameters, i.e., plant species number, cover and community composition, life forms and strategies, as well as basic soil properties were assessed. Although the heaps contained high concentrations of metals, namely Cd, Pb and Zn, they were characterised by higher cover and diversity of understory vegetation, including ancient forest and endangered species, in comparison to their surroundings. They were also characterised by the distinct species composition of their plant communities. This might have resulted from the beneficial influence of high pH and Ca content originating from waste rock composed of dolomite and calcite, as well as from increased habitat heterogeneity, e.g. soil skeleton and steeper slopes. Another important factor influencing the richness and composition of understory was tree cover, which relates to the light transmissibility of the canopy. Our study proved that the disturbance brought about by the former mining and processing of metal ores led to the formation of species-rich understory with high frequency and cover of naturally-valuable species. Copyright © 2017 Elsevier B

  7. Numerical Modelling of Vegetation Flow Interaction: the Wienfluss Test Case

    NASA Astrophysics Data System (ADS)

    Wilson, C.; Yagci, O.; Rauch, H.; Stoesser, T.

    2003-04-01

    We apply a three-dimensional computational fluid dynamics code based on a finite-volume discretisation to a 170m test reach of the a river in Vienna. One of the primary aims of this paper is to test various methods for representing the flow resistance of natural vegetation. The two approaches considered vary in complexity and could be practically implemented and applied within 2D and 3D flood modelling tools. The first approach uses empirical relationships derived from the laboratory data and modifies the existing friction term in the momentum equations. While the second approach introduces a drag related sink term in addition to the bed friction term. The roughness closure models considered do not modify the turbulence model (in this case the k-e model) and hence do not require re-calibration for each application. The test reach is straight and comprises an asymmetrical compound channel that is vegetated on the floodplain by willows and unvegetated within the main channel. The development of the willows has been monitored over a four year period and plant parameters which characterise the dimensions of individual trees and their distribution have been quantified. Further, streamwise velocity data of high-spatial resolution has been collected at one cross-section for a series of flood events. The performance of each approach is quantified in terms of its ability to reproduce the streamwise velocity distribution in a partially vegetated channel. Different parameter tests are conducted to allow the sensitivity of the computed velocities against mesh resolution, and other important plant properties to be examined. For both flow resistance approaches, reasonable agreement is found between the measured and computed floodplain velocities.

  8. Effect of vegetation on the presence and genetic diversity of Bacillus thuringiensis in soil.

    PubMed

    Ricieto, Ana Paula Scaramal; Fazion, Fernanda Aparecida Pires; Carvalho Filho, Celso Duarte; Vilas-Boas, Laurival Antonio; Vilas-Bôas, Gislayne Trindade

    2013-01-01

    Bacillus thuringiensis isolates were obtained from soil samples collected at different sites located in the same region but with different vegetation. The sites showed different frequencies of B. thuringiensis, depending on the type of vegetation. Strains of B. thuringiensis were found to be less common in samples of riparian forest soil than in soil of other types of vegetation. The rate of occurrence of B. thuringiensis in the samples also varied according to the vegetation. These results show that whenever this bacterium was found, it showed a high rate of occurrence, indicating that this species could be better adapted to using soil as a reservoir than other Bacillus species. The presence of cry genes was analyzed by polymerase chain reaction, and genes that exhibited activity against Diptera species were the most commonly found. The isolates obtained were characterized by random amplified polymorphic DNA, and 50% were clustered into clonal groups. These results demonstrated the possible occurrence of a high number of genetically similar strains when samples are collected from the same region, even if they are from locations with different vegetation.

  9. PROP taster status not related to reported cruciferous vegetable intake among ethnically diverse children

    PubMed Central

    Baranowski, Tom; Baranowski, Janice C; Watson, Kathleen B; Jago, Russell; Islam, Noemi; Beltran, Alicia; Martin, Shelby J; Nguyen, Nga; Tepper, Beverly J

    2011-01-01

    Sensitivity to the taste of 6-n-propylthiouracil (PROP) (a bitter tasting chemical related to the phenylthiocarbamide found in cruciferous vegetables) has been related to dietary intake or preferences of cruciferous vegetables among adults and young children, but not middle aged children or adolescents. We hypothesized that PROP taste sensitivity is related to lower reported dietary intake of cruciferous vegetables, primarily among younger children (i.e. a moderating effect of child age). This study examined the relationship of PROP sensitivity to reported dietary intake across three days in two age groups of youth (9–10 years and 17–18 year), while statistically controlling for physical activity, social desirability and reporting bias. Cross sectional design was employed with a multi-ethnic (White, African American, Hispanic, and Other) sample of 843 males and females. Children were recruited from and data were collected in local elementary and high schools that had at least 30% ethnic minority enrollment. Children providing nonplausible reports of dietary intake were deleted from the analyses. BMI was calculated and expressed in z-scores. Energy intake and physical activity were measured by three telephone conducted 24-hour dietary recalls with the Nutrient Data System for Research (NDSR) and 5 days of Actigraph activity monitor. The primary analyses included 347 students. PROP sensitivity was not related to intake of cruciferous vegetables. Intakes of the cruciferous vegetables were low, which may explain the lack of relationship. PMID:21925344

  10. Vegetation Monitoring with Gaussian Processes and Latent Force Models

    NASA Astrophysics Data System (ADS)

    Camps-Valls, Gustau; Svendsen, Daniel; Martino, Luca; Campos, Manuel; Luengo, David

    2017-04-01

    Monitoring vegetation by biophysical parameter retrieval from Earth observation data is a challenging problem, where machine learning is currently a key player. Neural networks, kernel methods, and Gaussian Process (GP) regression have excelled in parameter retrieval tasks at both local and global scales. GP regression is based on solid Bayesian statistics, yield efficient and accurate parameter estimates, and provides interesting advantages over competing machine learning approaches such as confidence intervals. However, GP models are hampered by lack of interpretability, that prevented the widespread adoption by a larger community. In this presentation we will summarize some of our latest developments to address this issue. We will review the main characteristics of GPs and their advantages in vegetation monitoring standard applications. Then, three advanced GP models will be introduced. First, we will derive sensitivity maps for the GP predictive function that allows us to obtain feature ranking from the model and to assess the influence of examples in the solution. Second, we will introduce a Joint GP (JGP) model that combines in situ measurements and simulated radiative transfer data in a single GP model. The JGP regression provides more sensible confidence intervals for the predictions, respects the physics of the underlying processes, and allows for transferability across time and space. Finally, a latent force model (LFM) for GP modeling that encodes ordinary differential equations to blend data-driven modeling and physical models of the system is presented. The LFM performs multi-output regression, adapts to the signal characteristics, is able to cope with missing data in the time series, and provides explicit latent functions that allow system analysis and evaluation. Empirical evidence of the performance of these models will be presented through illustrative examples.

  11. Land Use Effects on Vegetation Diversity in High-Elevation Ecosystems: a Comparison of Disturbed and Undisturbed Paramos

    NASA Astrophysics Data System (ADS)

    Avery, W. A.; Riveros-Iregui, D.; Jaimes, J. C.; Washington-Allen, R. A.; Delgado, A.

    2012-12-01

    The relationship between vegetation density, diversity, and structure in a given ecosystem and the capacity for that ecosystem to provide services has been widely investigated. However, the capacity of ecological systems to adapt to various degrees of anthropogenic land use represents a significant challenge in scientific investigations. We examined the effects of disturbance on vegetation diversity and ecosystem function across two paramos in the Andes Mountains of Colombia. The paramo, an alpine meadow that occurs at elevations above 3,000 m mainly in South America, is the major drinking water provider for the Andean highlands. These meadows collect water during the rainy season and release it during the dry season. The goal of this study is to elucidate the relationship between land use, vegetation biodiversity, and ecosystem services. Plant species richness was collected in two paramo watersheds with similar elevation and climatic conditions but with different historic land use, including potato cultivation and cattle grazing. Leaf area index (LAI), canopy cover, species richness and height diversity was quantified using a plant canopy analyzer and terrestrial LiDAR across thirty-six 1-m x1-m plots in each watershed. Results show that species richness is higher in the undisturbed paramo watershed than in the disturbed site. However, species complexity and richness increase in areas closer to streams in both watersheds, suggesting that ecosystem adaptation to disturbance is dependant on landscape position. Our results highlight that paramo ecosystems are vulnerable to human-induced disturbance and their capacity to respond to such disturbance is dependent on proximity to streams.

  12. Predicting use of ineffective vegetable parenting practices with the Model of Goal Directed Behavior

    USDA-ARS?s Scientific Manuscript database

    Increasing a parent's ability to influence a child's vegetable intake may require reducing the parent's use of ineffective vegetable parenting practices (IVPP). To understand the influences on IVPP, this study modeled use of IVPP using validated scales from a Model of Goal Directed Vegetable Parenti...

  13. Predicting use of effective vegetable parenting practices with the Model of Goal Directed Behavior

    USDA-ARS?s Scientific Manuscript database

    Our objective was to model effective vegetable parenting practices using the Model of Goal Directed Vegetable Parenting Practices construct scales. An internet survey was conducted with 307 parents (mostly mothers) of preschoolers in Houston, Texas to assess their agreement with effective vegetable ...

  14. Modeling Vernal Pool Hydrology and Vegetation in the Sierra Nevadas

    NASA Astrophysics Data System (ADS)

    Montrone, A. K.; Saito, L.; Weisberg, P.; Gosejohan, M.

    2012-12-01

    Vernal pools are geographic depressions with relatively impermeable substrates that are subject to four distinct seasons in mountainous regions: they fill with snow in the winter, melt into inundated pools in the spring, become unsaturated and vegetated by summer, then dry and become fully desiccated by fall. Vernal pools in California are greatly threatened. Over 90% of the pools in California have been destroyed by urbanization and other land use changes and continue to disappear with population growth. Furthermore, these pools face threats posed by climate change due to altered precipitation and temperature regimes. In the context of anthropogenic climate change, we are evaluating the direct and indirect effects of grazing management on ecohydrology and plant community structure in vernal pools Northern Sierra Nevada mountains. Hydrologic models of vernal pool basins, driven by climatic variables, are used to 1) determine if a changing climate will alter the magnitude and spatial distribution of inundation period within the pools; 2) determine how the available habitat for vernal pool vegetation specialists will change with climate change; 3) determine if increased soil compaction due to cattle grazing can help mitigate effects of climate change resulting from changes in hydraulic conductivity; and 4) determine the importance of spatial resolution in constructing the physical representation of the pools within the hydrologic models. Preliminary results from the models including calibration error metrics and hydroperiod impacts of grazing for models with varying spatial complexity will be presented.

  15. Models of life: epigenetics, diversity and cycles.

    PubMed

    Sneppen, Kim

    2017-04-01

    This review emphasizes aspects of biology that can be understood through repeated applications of simple causal rules. The selected topics include perspectives on gene regulation, phage lambda development, epigenetics, microbial ecology, as well as model approaches to diversity and to punctuated equilibrium in evolution. Two outstanding features are repeatedly described. One is the minimal number of rules to sustain specific states of complex systems for a long time. The other is the collapse of such states and the subsequent dynamical cycle of situations that restitute the system to a potentially new metastable state.

  16. Models of life: epigenetics, diversity and cycles

    NASA Astrophysics Data System (ADS)

    Sneppen, Kim

    2017-04-01

    This review emphasizes aspects of biology that can be understood through repeated applications of simple causal rules. The selected topics include perspectives on gene regulation, phage lambda development, epigenetics, microbial ecology, as well as model approaches to diversity and to punctuated equilibrium in evolution. Two outstanding features are repeatedly described. One is the minimal number of rules to sustain specific states of complex systems for a long time. The other is the collapse of such states and the subsequent dynamical cycle of situations that restitute the system to a potentially new metastable state.

  17. MODELING DYNAMIC VEGETATION RESPONSE TO RAPID CLIMATE CHANGE USING BIOCLIMATIC CLASSIFICATION

    EPA Science Inventory

    Modeling potential global redistribution of terrestrial vegetation frequently is based on bioclimatic classifications which relate static regional vegetation zones (biomes) to a set of static climate parameters. The equilibrium character of the relationships limits our confidence...

  18. MODELING DYNAMIC VEGETATION RESPONSE TO RAPID CLIMATE CHANGE USING BIOCLIMATIC CLASSIFICATION

    EPA Science Inventory

    Modeling potential global redistribution of terrestrial vegetation frequently is based on bioclimatic classifications which relate static regional vegetation zones (biomes) to a set of static climate parameters. The equilibrium character of the relationships limits our confidence...

  19. Inversion of canopy reflectance models for estimation of vegetation parameters

    NASA Technical Reports Server (NTRS)

    Goel, Narendra S.

    1987-01-01

    One of the keys to successful remote sensing of vegetation is to be able to estimate important agronomic parameters like leaf area index (LAI) and biomass (BM) from the bidirectional canopy reflectance (CR) data obtained by a space-shuttle or satellite borne sensor. One approach for such an estimation is through inversion of CR models which relate these parameters to CR. The feasibility of this approach was shown. The overall objective of the research carried out was to address heretofore uninvestigated but important fundamental issues, develop the inversion technique further, and delineate its strengths and limitations.

  20. Modeling the backscattering and transmission properties of vegetation canopies

    NASA Technical Reports Server (NTRS)

    Allen, C. T.; Ulaby, F. T.

    1984-01-01

    Experimental measurements of canopy attenuation at 10.2 GHz (X-band) for canopies of wheat and soybeans, experimental observations of the effect upon the microwave backscattering coefficient (sigma) of free water in a vegetation canopy, and experimental measurements of sigma (10.2 GHz, 50 deg, VV and VH polarization) of 30 agricultural fields over the growing season of each crop are discussed. The measurements of the canopy attenuation through wheat independently determined the attenuation resulting from the wheat heads and that from the stalks. An experiment conducted to simulate the effects of rain or dew on sigma showed that sigma increases by about 3 dB as a result of spraying a vegetation canopy with water. The temporal observations of sigma for the 30 agricultural fields (10 each of wheat, corn, and soybeans) indicated fields of the same crop type exhibits similar temporal patterns. Models previously reported were tested using these multitemporal sigma data, and a new model for each crop type was developed and tested. The new models proved to be superior to the previous ones.

  1. Modeling vertebrate diversity in Oregon using satellite imagery

    NASA Astrophysics Data System (ADS)

    Cablk, Mary Elizabeth

    Vertebrate diversity was modeled for the state of Oregon using a parametric approach to regression tree analysis. This exploratory data analysis effectively modeled the non-linear relationships between vertebrate richness and phenology, terrain, and climate. Phenology was derived from time-series NOAA-AVHRR satellite imagery for the year 1992 using two methods: principal component analysis and derivation of EROS data center greenness metrics. These two measures of spatial and temporal vegetation condition incorporated the critical temporal element in this analysis. The first three principal components were shown to contain spatial and temporal information about the landscape and discriminated phenologically distinct regions in Oregon. Principal components 2 and 3, 6 greenness metrics, elevation, slope, aspect, annual precipitation, and annual seasonal temperature difference were investigated as correlates to amphibians, birds, all vertebrates, reptiles, and mammals. Variation explained for each regression tree by taxa were: amphibians (91%), birds (67%), all vertebrates (66%), reptiles (57%), and mammals (55%). Spatial statistics were used to quantify the pattern of each taxa and assess validity of resulting predictions from regression tree models. Regression tree analysis was relatively robust against spatial autocorrelation in the response data and graphical results indicated models were well fit to the data.

  2. Diversity, density, and development of early vegetation in a small clear-cut environment

    Treesearch

    Philip M. McDonald

    1999-01-01

    On a high quality site in northern California, frequency, density, foliar cover, and height were measured on every plant species present in an 8-acre clear-cut opening each year from 1976 through 1980. Plant species numbered 71, although no more than 62 were present during a given year. Categories of vegetation with the most plants per acre initially were shrubs,...

  3. School-Based Promotion of Fruit and Vegetable Consumption in Multiculturally Diverse, Urban Schools

    ERIC Educational Resources Information Center

    Blom-Hoffman, Jessica

    2007-01-01

    Rates of childhood overweight have reached epidemic proportions (U.S. Department of Health and Human Services, 2001), and schools have been called on to play a role in the prevention of this medical condition. This article describes a multiyear health promotion effort--the Athletes in Service fruit and vegetable (F&V) promotion program--which…

  4. Toward a mechanistic modeling of nitrogen limitation on vegetation dynamics

    SciTech Connect

    Xu, Chonggang; Fisher, Rosie; Wullschleger, Stan D; Wilson, Cathy; Cai, Michael; McDowell, Nathan

    2012-01-01

    Nitrogen is a dominant regulator of vegetation dynamics, net primary production, and terrestrial carbon cycles; however, most ecosystem models use a rather simplistic relationship between leaf nitrogen content and photosynthetic capacity. Such an approach does not consider how patterns of nitrogen allocation may change with differences in light intensity, growing-season temperature and CO{sub 2} concentration. To account for this known variability in nitrogen-photosynthesis relationships, we develop a mechanistic nitrogen allocation model based on a trade-off of nitrogen allocated between growth and storage, and an optimization of nitrogen allocated among light capture, electron transport, carboxylation, and respiration. The developed model is able to predict the acclimation of photosynthetic capacity to changes in CO{sub 2} concentration, temperature, and radiation when evaluated against published data of V{sub c,max} (maximum carboxylation rate) and J{sub max} (maximum electron transport rate). A sensitivity analysis of the model for herbaceous plants, deciduous and evergreen trees implies that elevated CO{sub 2} concentrations lead to lower allocation of nitrogen to carboxylation but higher allocation to storage. Higher growing-season temperatures cause lower allocation of nitrogen to carboxylation, due to higher nitrogen requirements for light capture pigments and for storage. Lower levels of radiation have a much stronger effect on allocation of nitrogen to carboxylation for herbaceous plants than for trees, resulting from higher nitrogen requirements for light capture for herbaceous plants. As far as we know, this is the first model of complete nitrogen allocation that simultaneously considers nitrogen allocation to light capture, electron transport, carboxylation, respiration and storage, and the responses of each to altered environmental conditions. We expect this model could potentially improve our confidence in simulations of carbon-nitrogen interactions

  5. Toward a Mechanistic Modeling of Nitrogen Limitation on Vegetation Dynamics

    PubMed Central

    Xu, Chonggang; Fisher, Rosie; Wullschleger, Stan D.; Wilson, Cathy J.; Cai, Michael; McDowell, Nate G.

    2012-01-01

    Nitrogen is a dominant regulator of vegetation dynamics, net primary production, and terrestrial carbon cycles; however, most ecosystem models use a rather simplistic relationship between leaf nitrogen content and photosynthetic capacity. Such an approach does not consider how patterns of nitrogen allocation may change with differences in light intensity, growing-season temperature and CO2 concentration. To account for this known variability in nitrogen-photosynthesis relationships, we develop a mechanistic nitrogen allocation model based on a trade-off of nitrogen allocated between growth and storage, and an optimization of nitrogen allocated among light capture, electron transport, carboxylation, and respiration. The developed model is able to predict the acclimation of photosynthetic capacity to changes in CO2 concentration, temperature, and radiation when evaluated against published data of Vc,max (maximum carboxylation rate) and Jmax (maximum electron transport rate). A sensitivity analysis of the model for herbaceous plants, deciduous and evergreen trees implies that elevated CO2 concentrations lead to lower allocation of nitrogen to carboxylation but higher allocation to storage. Higher growing-season temperatures cause lower allocation of nitrogen to carboxylation, due to higher nitrogen requirements for light capture pigments and for storage. Lower levels of radiation have a much stronger effect on allocation of nitrogen to carboxylation for herbaceous plants than for trees, resulting from higher nitrogen requirements for light capture for herbaceous plants. As far as we know, this is the first model of complete nitrogen allocation that simultaneously considers nitrogen allocation to light capture, electron transport, carboxylation, respiration and storage, and the responses of each to altered environmental conditions. We expect this model could potentially improve our confidence in simulations of carbon-nitrogen interactions and the vegetation feedbacks

  6. Farmers' market use is associated with fruit and vegetable consumption in diverse southern rural communities.

    PubMed

    Jilcott Pitts, Stephanie B; Gustafson, Alison; Wu, Qiang; Leah Mayo, Mariel; Ward, Rachel K; McGuirt, Jared T; Rafferty, Ann P; Lancaster, Mandee F; Evenson, Kelly R; Keyserling, Thomas C; Ammerman, Alice S

    2014-01-09

    While farmers' markets are a potential strategy to increase access to fruits and vegetables in rural areas, more information is needed regarding use of farmers' markets among rural residents. Thus, this study's purpose was to examine (1) socio-demographic characteristics of participants; (2) barriers and facilitators to farmers' market shopping in southern rural communities; and (3) associations between farmers' market use with fruit and vegetable consumption and body mass index (BMI). Cross-sectional surveys were conducted with a purposive sample of farmers' market customers and a representative sample of primary household food shoppers in eastern North Carolina (NC) and the Appalachian region of Kentucky (KY). Customers were interviewed using an intercept survey instrument at farmers' markets. Representative samples of primary food shoppers were identified via random digit dial (RDD) cellular phone and landline methods in counties that had at least one farmers' market. All questionnaires assessed socio-demographic characteristics, food shopping patterns, barriers to and facilitators of farmers' market shopping, fruit and vegetable consumption and self-reported height and weight. The main outcome measures were fruit and vegetable consumption and BMI. Descriptive statistics were used to examine socio-demographic characteristics, food shopping patterns, and barriers and facilitators to farmers' market shopping. Linear regression analyses were used to examine associations between farmers' market use with fruit and vegetable consumption and BMI, controlling for age, race, education, and gender. Among farmers' market customers, 44% and 55% (NC and KY customers, respectively) reported shopping at a farmers' market at least weekly, compared to 16% and 18% of NC and KY RDD respondents. Frequently reported barriers to farmers' market shopping were market days and hours, "only come when I need something", extreme weather, and market location. Among the KY farmers' market

  7. Farmers’ market use is associated with fruit and vegetable consumption in diverse southern rural communities

    PubMed Central

    2014-01-01

    Background While farmers’ markets are a potential strategy to increase access to fruits and vegetables in rural areas, more information is needed regarding use of farmers’ markets among rural residents. Thus, this study’s purpose was to examine (1) socio-demographic characteristics of participants; (2) barriers and facilitators to farmers’ market shopping in southern rural communities; and (3) associations between farmers’ market use with fruit and vegetable consumption and body mass index (BMI). Methods Cross-sectional surveys were conducted with a purposive sample of farmers’ market customers and a representative sample of primary household food shoppers in eastern North Carolina (NC) and the Appalachian region of Kentucky (KY). Customers were interviewed using an intercept survey instrument at farmers’ markets. Representative samples of primary food shoppers were identified via random digit dial (RDD) cellular phone and landline methods in counties that had at least one farmers’ market. All questionnaires assessed socio-demographic characteristics, food shopping patterns, barriers to and facilitators of farmers’ market shopping, fruit and vegetable consumption and self-reported height and weight. The main outcome measures were fruit and vegetable consumption and BMI. Descriptive statistics were used to examine socio-demographic characteristics, food shopping patterns, and barriers and facilitators to farmers’ market shopping. Linear regression analyses were used to examine associations between farmers’ market use with fruit and vegetable consumption and BMI, controlling for age, race, education, and gender. Results Among farmers’ market customers, 44% and 55% (NC and KY customers, respectively) reported shopping at a farmers’ market at least weekly, compared to 16% and 18% of NC and KY RDD respondents. Frequently reported barriers to farmers’ market shopping were market days and hours, “only come when I need something”, extreme

  8. Ant diversity and its relationship with vegetation and soil factors in an alluvial fan of the Tehuacán Valley, Mexico

    NASA Astrophysics Data System (ADS)

    Ríos-Casanova, Leticia; Valiente-Banuet, Alfonso; Rico-Gray, Víctor

    2006-05-01

    In this study, we analyze the ant community found along an alluvial fan located in the Tehuacán Valley, central Mexico. Considering that this fan is composed of four terraces with different soils and vegetation structures, our main goal was to determine whether there are significant differences in ant diversity among terraces. To accomplish this goal, we determine species richness and abundance in order to calculate diversity and evenness indices. In addition, we classify species in different feeding guilds to evaluate whether differences among terraces exist. We expected higher ant diversity and variety of food guilds in terraces with sandy soils and complex vegetation structures than in terraces with argillic and calcic horizons. Correlations between several diversity parameters, and soil percent-sand and vegetation structure were also conducted. A total of 26 ant species were recorded along the fan. Species richness was not different among terraces whereas abundance was higher in sandy soils and on terraces with complex vegetation structure. Particularly, the abundance of the harvester ant Pogonomyrmex barbatus was higher in these terraces decreasing total ant diversity and evenness. Species richness within feeding guilds was similar among terraces with the generalized foragers as the most common. Our work suggests that percentage of sand in the soil and complexity of vegetation structure of the alluvial fan studied might be influencing ant distribution and favoring the abundance of numerically dominant species which could be affecting the diversity patterns of the whole community.

  9. Irrigation Requirement Estimation Using Vegetation Indices and Inverse Biophysical Modeling

    NASA Technical Reports Server (NTRS)

    Bounoua, Lahouari; Imhoff, Marc L.; Franks, Shannon

    2010-01-01

    We explore an inverse biophysical modeling process forced by satellite and climatological data to quantify irrigation requirements in semi-arid agricultural areas. We constrain the carbon and water cycles modeled under both equilibrium, balance between vegetation and climate, and non-equilibrium, water added through irrigation. We postulate that the degree to which irrigated dry lands vary from equilibrium climate conditions is related to the amount of irrigation. The amount of water required over and above precipitation is considered as an irrigation requirement. For July, results show that spray irrigation resulted in an additional amount of water of 1.3 mm per occurrence with a frequency of 24.6 hours. In contrast, the drip irrigation required only 0.6 mm every 45.6 hours or 46% of that simulated by the spray irrigation. The modeled estimates account for 87% of the total reported irrigation water use, when soil salinity is not important and 66% in saline lands.

  10. 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...

  11. 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...

  12. Modelling the risk of ecosystem disruption in Europe with a dynamic vegetation model

    NASA Astrophysics Data System (ADS)

    Dury, M.; Hambuckers, A.; Warnant, P.; Jacquemin, I.; Thuiller, W.; François, L.

    2012-04-01

    What will be the European ecosystem responses to future climate? With unprecedented speed and extent, the projected climate change might lead to a disruption of terrestrial plants functioning in many regions. In the framework of the EcoChange project, transient projections over the 1901-2100 period have been performed with a process-based dynamic vegetation model, CARAIB DVM (Dury et al., 2011, iForest 4: 82, 99). The vegetation model was driven by the outputs of four climate models under the SRES A1B scenario: the ARPEGE/Climate model and three regional climate models (KNMI-RACMO2, DMI-HIRHAM5 and HC-HadRM3Q0 RCMs) from the European Union project ENSEMBLES. DVMs are appropriate tools to apprehend potential climate change impacts on ecosystems and identify threatened regions over Europe. CARAIB outputs (soil moisture, runoff, net primary productivity, fire, etc.) were used to characterise the ecosystem evolution. To assess consequences on biodiversity, the evolution of 100 natural common European species (47 herbs, 12 shrubs and 41 trees) has been studied year-to-year over the 1901-2100 period. Under the combined effects of projected changes particularly in temperature and precipitations, CARAIB simulates important reductions in the annual soil water content. The species productivities vary strongly from year to year reaching during the driest years values much lower than present-day average productivities. According to CARAIB, a lot of species might go beyond their water tolerance very frequently, particularly after 2050, due to more intense summer droughts. In the northern part of Europe and in the Alps, with reduced temperature variability and positive soil water anomalies, NPP variability tends to decrease. Regions with more severe droughts might also be affected by an increase of the frequency and intensity of wildfires. With this background, the species distributions might be strongly modified at the end of the century. 15% of tree species and 30% of herb and

  13. Richness, diversity and evenness of vegetation upon rehabilitation of gypsum mine spoiled lands in the Indian arid zone

    USGS Publications Warehouse

    Kumar, S.; Sharma, K.D.; Sharma, U.K.; Gough, L.P.

    1998-01-01

    Richness, diversity and evenness of vegetation, after rehabilitation of gypsum mine spoils at Barmer were investigated in plots protected and planted one year and four years ago. There were four water harvesting treatments, viz., half-moon terraces, micro-catchments with 5% slope, ridge and furrow and control, wherein, indigenous and exotic trees and shrubs were planted at 5 ?? 5 m spacing. Sampling of the planted and natural vegetation, using quadrats and transacts, revealed much less species richness in unplanted control as compared to all treatments and in all the years. The species richness that increased initially (within one year) gradually declined over time (during four year), though the extent varied in different treatments. The water harvesting treatment showing maximum initial increase in richness also showed maximum decline over time, though decline was more in annual species. Two perennial species increased in richness with time. This was further proved from the trends in diversity and evenness indices. It was concluded that natural successional process was accelerated by rehabilitation providing stability to the habitat.

  14. Monte Carlo: an application to modeling remote sensing of vegetation - coherent and incoherent models

    NASA Astrophysics Data System (ADS)

    Bruscaglioni, Piero; Poggi, P.; Macelloni, Giovanni; Paloscia, Simonetta

    2003-04-01

    This paper describes an application of the Monte Carlo method to the evaluation of backscattering response to microwave sounding of vegetation. After a brief introductory discussion on the different approaches commonly employed to the numerical simulation of scattering from vegetation, we describe our model based on representing the vegetation medium as a collection of elementary scatterers of simple shapes, and dealing directly with electromagnetic field interaction with these elements. Plant structures are built assembling the single elements by the Lindenmayer systems fractal technique. We presents some examples of computations on models of different kinds of vegetation showing the potential of modeling in understanding scattering behavior. A brief discussion on the issue of second order scattering effects is also included.

  15. [Effects of landscape and vegetation structure on the diversity of phyllostomid bats (Chiroptera: Phyllostomidae) in Oaxaca, Mexico].

    PubMed

    García-García, José Luis; Santos-Moreno, Antonio

    2014-03-01

    The tropical forest fragmentation is known to affect the spatial structure of the landscape and habitat. These alterations can modify the attributes of bat assemblages, however, this phenomenon has been little studied and understood. In this work we evaluated the structure of landscape (i.e. composition and configuration) and vegetation, and its relationship with assemblage- and population-level characteristics of phyllostomid bats in a tropical rainforest of Southeastern Mexico. For this, we previously selected 12 sites located in continuous and fragmented forests, where bats were captured using mist nets during a two years sampling effort (144 nights). Bats relative abundance, species richness (diversity of order 0, 0D), Shannon diversity index (1D) and Simpson index (2D) were evaluated in all sites, and their relationship with seven measures of landscape structure and seven measures of vegetation structure was described using a Hierarchical Partitioning Analysis. A total of 1 840 individuals of 29 species of phyllostomid bats were captured in this period. Differences in the assemblages were manifested only in the relative abundance and not in the richness of the species. The assemblages of fragmented forest exhibited greater variation in species composition and a greater abundance of frugivorous and nectarivorous bats in comparison with the assemblages of continuous forest. The landscape configuration was related to the assemblage- and population-level attributes, contrasting with previous studies where the composition was a key element. At habitat level, tree density and canopy cover determined the abundance of bats. Nectarivorous and frugivorous bats were mostly found in disturbed vegetation landscapes, primarily due to landscape configuration (e.g. edge density). This phenomenon could be a response to the availability of food in primary and intermediate successional stages, which are characterized by an abundance of food value.

  16. Modeling low-height vegetation with airborne LiDAR

    USDA-ARS?s Scientific Manuscript database

    Low-height vegetation, common in semiarid regions, is difficult to characterize with LiDAR (Light Detection and Ranging) due to similarities, in time and space, of the point returns of vegetation and ground. Other complications may occur due to the low-height vegetation structural characteristics a...

  17. Psychometric assessment of scales for a Model of Goal Directed Vegetable Parenting Practices (MGDVPP)

    USDA-ARS?s Scientific Manuscript database

    Vegetable intake has been related to lower risk of chronic illnesses in the adult years. The habit of vegetable intake should be established early in life, but many parents of preschoolers report not being able to get their child to eat vegetables. The Model of Goal Directed Behavior (MGDB) has been...

  18. Modeling of two-dimensional overland flow in a vegetative filter

    Treesearch

    Matthew J. Helmers; Dean E. Eisenhauer; Thomas G. Franti; Michael G. Dosskey

    2002-01-01

    Water transports sediment and other pollutants through vegetative filters. It is often assumed that the overland flow is uniformly distributed across the vegetative filter, but this research indicates otherwise. The objective of this study was to model the two-dimensional overland water flow through a vegetative filter, accounting for variation in microtopography,...

  19. Diversity of Cronobacter spp. isolates from the vegetables in the middle-east coastline of China.

    PubMed

    Chen, Wanyi; Yang, Jielin; You, Chunping; Liu, Zhenmin

    2016-06-01

    Cronobacter spp. has caused life-threatening neonatal infections mainly resulted from consumption of contaminated powdered infant formula. A total of 102 vegetable samples from retail markets were evaluated for the presence of Cronobacter spp. Thirty-five presumptive Cronobacter isolates were isolated and identified using API 20E and 16S rDNA sequencing analyses. All isolates and type strains were characterized using enterobacterial repetitive intergenic consensus sequence PCR (ERIC-PCR), and genetic profiles of cluster analysis from this molecular typing test clearly showed that there were differences among isolates from different vegetables. A polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) based on the amplification of the gyrB gene (1258 bp) was developed to differentiate among Cronobacter species. A new PCR-RFLP assay based on the amplification of the gyrB gene using Alu I and Hinf I endonuclease combination is established and it has been confirmed an accurate and rapid subtyping method to differentiate Cronobacter species. Sequence analysis of the gyrB gene was proven to be suitable for the phylogenetic analysis of the Cronobacter strains, which has much better resolution based on SNPs in the identification of Cronobacter species specificity than PCR-RFLP and ERIC-PCR. Our study further confirmed that vegetables are one of the most common habitats or sources of Cronobacter spp. contamination in the middle-east coastline of China.

  20. Coppice abandonment and its implications for species diversity in forest vegetation.

    PubMed

    Müllerová, Jana; Hédl, Radim; Szabó, Péter

    2015-05-01

    Coppicing, once a common type of management in European broadleaved forests, was abandoned in many places after WWII. This form of management provided a variety of structural and microclimatic conditions for tree and understorey vegetation. After the abandonment of this intensive management, succession towards mature close forests ensued, and suitable habitats for species ecologically connected to coppicing were reduced. In our study, we chose a region in central Europe where coppicing was the dominant type of forest management until the first half of the 20(th) century but was abandoned after WWII. We investigated long-term changes in both woody and herbaceous species composition in the Lower Morava UNESCO Biosphere Reserve using historical sources and vegetation plot resurveys from the 17(th) to the 21(st) century. The impact of coppice abandonment on vegetation composition and on the conservation value of forests was evaluated. Dominant tree species appeared to be very stable throughout the past four centuries, but changes occurred in their proportions. A shift from species rich oak-hornbeam woodland towards species poorer communities with increasing proportions of lime, ash and maple was observed after the abandonment of coppicing. The observed tendencies partly differed according to site and data source. The conservation value of forests was measured as the occurrence of red-list species, which were considerably reduced after coppice abandonment. To stop the process of biodiversity loss and support the goals of nature conservation, the re-establishment of coppice management is proposed.

  1. The Jena Diversity Model: Towards a Richer Representation of the Terrestrial Biosphere for Earth System Modelling

    NASA Astrophysics Data System (ADS)

    Pavlick, R.; Reu, B.; Bohn, K.; Dyke, J.; Kleidon, A.

    2010-12-01

    The terrestrial biosphere is a complex, self-organizing system which is continually both adapting to and altering its global environment. It also exhibits a vast diversity of vegetation forms and functioning. However, the terrestrial biosphere components within current state-of-the-art Earth System Models abstract this diversity in to a handful of relatively static plant functional types. These coarse and static representations of functional diversity might contribute to overly pessimistic projections regarding terrestrial ecosystem responses to scenarios of global change (e.g. Amazonian and boreal forest diebacks). In the Jena Diversity (JeDi) model, we introduce a new approach to vegetation modelling with a richer representation of functional diversity, based not on plant functional types, but on unavoidable plant ecophysiological trade-offs, which we hypothesize should be more stable in time. The JeDi model tests a large number of plant growth strategies. Each growth strategy is simulated using a set of randomly generated parameter values, which characterize its functioning in terms of carbon allocation, ecophysiology, and phenology, which are then linked to the growing conditions at the land surface. The model is constructed in such a way that these parameters inherently lead to ecophysiological trade-offs, which determine whether a growth strategy is able to survive and reproduce under the prevalent climatic conditions. Kleidon and Mooney (2000) demonstrated that this approach is capable of reproducing the geographic distribution of species richness. More recently, we have shown the JeDi model can explain other biogeographical phenomena including the present-day global pattern of biomes (Reu et al., accepted), ecosystem evenness (Kleidon et al. 2009), and possible mechanisms for biome shifts and biodiversity changes under scenarios of global warming (Reu et al., submitted). We have also evaluated the simulated biogeochemical fluxes from JeDi against a variety

  2. Modeling terrestrial carbon and water dynamics across climatic gradients: does plant trait diversity matter?

    PubMed

    Pappas, Christoforos; Fatichi, Simone; Burlando, Paolo

    2016-01-01

    Plant trait diversity in many vegetation models is crudely represented using a discrete classification of a handful of 'plant types' (named plant functional types; PFTs). The parameterization of PFTs reflects mean properties of observed plant traits over broad categories ignoring most of the inter- and intraspecific plant trait variability. Taking advantage of a multivariate leaf-trait distribution (leaf economics spectrum), as well as documented plant drought strategies, we generate an ensemble of hypothetical species with coordinated attributes, rather than using few PFTs. The behavior of these proxy species is tested using a mechanistic ecohydrological model that translates plant traits into plant performance. Simulations are carried out for a range of climates representative of different elevations and wetness conditions in the European Alps. Using this framework we investigate the sensitivity of ecosystem response to plant trait diversity and compare it with the sensitivity to climate variability. Plant trait diversity leads to highly divergent vegetation carbon dynamics (fluxes and pools) and to a lesser extent water fluxes (transpiration). Abiotic variables, such as soil water content and evaporation, are only marginally affected. These results highlight the need for revising the representation of plant attributes in vegetation models. Probabilistic approaches, based on observed multivariate whole-plant trait distributions, provide a viable alternative.

  3. Importance of vegetation classes in modeling CH4 emissions from boreal and subarctic wetlands in Finland.

    PubMed

    Li, Tingting; Raivonen, Maarit; Alekseychik, Pavel; Aurela, Mika; Lohila, Annalea; Zheng, Xunhua; Zhang, Qing; Wang, Guocheng; Mammarella, Ivan; Rinne, Janne; Yu, Lijun; Xie, Baohua; Vesala, Timo; Zhang, Wen

    2016-12-01

    Boreal/arctic wetlands are dominated by diverse plant species, which vary in their contribution to CH4 production, oxidation and transport processes. Earlier studies have often lumped the processes all together, which may induce large uncertainties into the results. We present a novel model, which includes three vegetation classes and can be used to simulate CH4 emissions from boreal and arctic treeless wetlands. The model is based on an earlier biogeophysical model, CH4MODwetland. We grouped the vegetation as graminoids, shrubs and Sphagnum and recalibrated the vegetation parameters according to their different CH4 production, oxidation and transport capacities. Then, we used eddy-covariance-based CH4 flux observations from a boreal (Siikaneva) and a subarctic fen (Lompolojänkkä) in Finland to validate the model. The results showed that the recalibrated model could generally simulate the seasonal patterns of the Finnish wetlands with different plant communities. The comparison between the simulated and measured daily CH4 fluxes resulted in a correlation coefficient (R(2)) of 0.82 with a slope of 1.0 and an intercept of -0.1mgm(-2)h(-1) for the Siikaneva site (n=2249, p<0.001) and an R(2) of 0.82 with a slope of 1.0 and an intercept of 0.0mgm(-2)h(-1) for the Lompolojänkkä site (n=1826, p<0.001). Compared with the original model, the recalibrated model in this study significantly improved the model efficiency (EF), from -5.5 to 0.8 at the Siikaneva site and from -0.4 to 0.8 at the Lompolojänkkä site. The simulated annual CH4 emissions ranged from 7 to 24gm(-2)yr(-1), which was consistent with the observations (7-22gm(-2)yr(-1)). However, there are some discrepancies between the simulated and observed daily CH4 fluxes for the Siikaneva site (RMSE=50.0%) and the Lompolojänkkä site (RMSE=47.9%). Model sensitivity analysis showed that increasing the proportion of the graminoids would significantly increase the CH4 emission levels. Our study demonstrated that

  4. Transition and pattern diversity in arid and semiarid grassland: A modeling study

    NASA Astrophysics Data System (ADS)

    Zeng, Xiaodong; Zeng, Xubin

    2007-12-01

    Abrupt transitions between large-scale grassland and desert in arid and semiarid regions have been observed in nature and reproduced by modeling studies. Observations also show the existence of nonuniform fine-scale vegetation patterns along the transition zone. This paper attempts to better understand these observations from two very different spatial scales. By explicitly introducing horizontal interaction terms into our previous dynamical grassland model, vegetation patterns with high diversities are found in the transition zone, and the system possesses an infinite number of equilibrium states in response to a given climatic forcing. The transition can be elucidated in two ways. In terms of the vegetation formations, the ecosystem undergoes the transition from uniform grassland to regular and irregular vegetation patterns, and then to pure desert as the moisture index (i.e., the ratio of precipitation over potential evaporation) decreases. In terms of biomass, the transition from grassland to desert goes through a narrow range of moisture index under which grassland is most fragile, as indicated by erratic vegetation patterns and large variation of average biomass. The existence of this range, however, has not been reported in previous modeling studies, and still needs to be validated using observational data.

  5. Numerical Model Sensitivity to Heterogeneous Satellite Derived Vegetation Roughness

    NASA Technical Reports Server (NTRS)

    Jasinski, Michael; Eastman, Joseph; Borak, Jordan

    2011-01-01

    The sensitivity of a mesoscale weather prediction model to a 1 km satellite-based vegetation roughness initialization is investigated for a domain within the south central United States. Three different roughness databases are employed: i) a control or standard lookup table roughness that is a function only of land cover type, ii) a spatially heterogeneous roughness database, specific to the domain, that was previously derived using a physically based procedure and Moderate Resolution Imaging Spectroradiometer (MODIS) imagery, and iii) a MODIS climatologic roughness database that like (i) is a function only of land cover type, but possesses domain specific mean values from (ii). The model used is the Weather Research and Forecast Model (WRF) coupled to the Community Land Model within the Land Information System (LIS). For each simulation, a statistical comparison is made between modeled results and ground observations within a domain including Oklahoma, Eastern Arkansas, and Northwest Louisiana during a 4-day period within IHOP 2002. Sensitivity analysis compares the impact the three roughness initializations on time-series temperature, precipitation probability of detection (POD), average wind speed, boundary layer height, and turbulent kinetic energy (TKE). Overall, the results indicate that, for the current investigation, replacement of the standard look-up table values with the satellite-derived values statistically improves model performance for most observed variables. Such natural roughness heterogeneity enhances the surface wind speed, PBL height and TKE production up to 10 percent, with a lesser effect over grassland, and greater effect over mixed land cover domains.

  6. Modeling radium and radon transport through soil and vegetation

    USGS Publications Warehouse

    Kozak, J.A.; Reeves, H.W.; Lewis, B.A.

    2003-01-01

    A one-dimensional flow and transport model was developed to describe the movement of two fluid phases, gas and water, within a porous medium and the transport of 226Ra and 222Rn within and between these two phases. Included in this model is the vegetative uptake of water and aqueous 226Ra and 222Rn that can be extracted from the soil via the transpiration stream. The mathematical model is formulated through a set of phase balance equations and a set of species balance equations. Mass exchange, sink terms and the dependence of physical properties upon phase composition couple the two sets of equations. Numerical solution of each set, with iteration between the sets, is carried out leading to a set-iterative compositional model. The Petrov-Galerkin finite element approach is used to allow for upstream weighting if required for a given simulation. Mass lumping improves solution convergence and stability behavior. The resulting numerical model was applied to four problems and was found to produce accurate, mass conservative solutions when compared to published experimental and numerical results and theoretical column experiments. Preliminary results suggest that the model can be used as an investigative tool to determine the feasibility of phytoremediating radium and radon-contaminated soil. ?? 2003 Elsevier Science B.V. All rights reserved.

  7. Mapping and modeling airborne urban phenanthrene distribution using vegetation biomonitoring

    NASA Astrophysics Data System (ADS)

    Noth, Elizabeth M.; Katharine Hammond, S.; Biging, Gregory S.; Tager, Ira B.

    2013-10-01

    To capture the spatial distribution of phenanthrene in an urban setting we used vegetation biomonitoring with Jeffrey pine trees (Pinus jeffreyi). The major challenge in characterizing spatial variation in polycyclic aromatic hydrocarbon (PAH) concentrations within a metropolitan area has been sampling at a fine enough resolution to observe the underlying spatial pattern. However, field and chamber studies show that the primary pathway through which PAHs enter plants is from air into leaves, making vegetation biomonitoring a feasible way to examine the spatial distribution of these compounds. Previous research has shown that phenanthrene has adverse health effects and that it is one of the most abundant PAHs in urban air. We collected 99 pine needle samples from 91 locations in Fresno in the morning on a winter day, and analyzed them for PAHs in the inner needle. All 99 pine needle samples had detectable levels of phenanthrene, with mean concentration of 41.0 ng g-1, median 36.9 ng g-1, and standard deviation of 28.5 ng g-1 fresh weight. The ratio of the 90th:10th percentile concentrations by location was 3.3. The phenanthrene distribution had a statistically significant Moran's I of 0.035, indicating a high degree of spatial clustering. We implemented land use regression to fit a model to our data. Our model was able to explain a moderate amount of the variability in the data (R2 = 0.56), likely reflecting the major sources of phenanthrene in Fresno. The spatial distribution of modeled airborne phenanthrene shows the influences of highways, railroads, and industrial and commercial zones.

  8. Using natural selection and optimization for smarter vegetation models - challenges and opportunities

    NASA Astrophysics Data System (ADS)

    Franklin, Oskar; Han, Wang; Dieckmann, Ulf; Cramer, Wolfgang; Brännström, Åke; Pietsch, Stephan; Rovenskaya, Elena; Prentice, Iain Colin

    2017-04-01

    Dynamic global vegetation models (DGVMs) are now indispensable for understanding the biosphere and for estimating the capacity of ecosystems to provide services. The models are continuously developed to include an increasing number of processes and to utilize the growing amounts of observed data becoming available. However, while the versatility of the models is increasing as new processes and variables are added, their accuracy suffers from the accumulation of uncertainty, especially in the absence of overarching principles controlling their concerted behaviour. We have initiated a collaborative working group to address this problem based on a 'missing law' - adaptation and optimization principles rooted in natural selection. Even though this 'missing law' constrains relationships between traits, and therefore can vastly reduce the number of uncertain parameters in ecosystem models, it has rarely been applied to DGVMs. Our recent research have shown that optimization- and trait-based models of gross primary production can be both much simpler and more accurate than current models based on fixed functional types, and that observed plant carbon allocations and distributions of plant functional traits are predictable with eco-evolutionary models. While there are also many other examples of the usefulness of these and other theoretical principles, it is not always straight-forward to make them operational in predictive models. In particular on longer time scales, the representation of functional diversity and the dynamical interactions among individuals and species presents a formidable challenge. Here we will present recent ideas on the use of adaptation and optimization principles in vegetation models, including examples of promising developments, but also limitations of the principles and some key challenges.

  9. Beyond Potential Vegetation II: Using Repeat Lidar Data on Changes in Vegetation Height to Test Model Predictions of Ecosystem Dynamics

    NASA Astrophysics Data System (ADS)

    Hurtt, G.; Thomas, R. Q.; Dubayah, R.

    2007-12-01

    Carbon estimates from terrestrial ecosystem models are limited by large uncertainties in the current state of the land surface, as previous disturbances have important and lasting influences on ecosystem structure and fluxes and can be difficult to detect or assess. Previous studies have illustrated how data on the vertical structure of vegetation from lidar can help to provide needed information on successional status for model initialization and constrain estimates of both carbon stock and fluxes. Here, we illustrate how repeat lidar data on vegetation structure can be used to test model predictions of ecosystem dynamics at a tropical forest site at La Selva, Costa Rica (108259 N, 848009 W). Airborne lidar remote sensing was used to measure spatial heterogeneity in the vertical structure of vegetation in 1998 and 2005. The ecosystem demography model (ED) was used to estimate corresponding patterns of carbon stocks, fluxes, and ecosystem dynamics during the interval. Lidar-initialized ED estimates of changes in maximum canopy height) were comparable to but significantly lower than observed (0.85 +/- 0.9 m observed vs. 0.53 +/- 0.4 m modeled) over the whole domain. Most of the model-data difference was due to growth of primary forest trees that exceeded model estimates (0.44 +/-0.9 m observed vs. 0.04 +/-0.1 m modeled), while the model-data comparison was significantly better over secondary forest areas (1.84 +/- 0.18 m observed vs. 1.71 +/-0.9 m modeled). The results of this study provide a promising illustration of the power of using repeat lidar data on changes in vegetation height to test estimates of ecosystem dynamics from height-structured ecosystem models. Extending these capabilities to regional and global scales will require repeat lidar data sets from space, and the continued development of height-structured ecosystem models.

  10. Predicting use of ineffective vegetable parenting practices with the Model of Goal Directed Behavior.

    PubMed

    Baranowski, Tom; Beltran, Alicia; Chen, Tzu-An; Thompson, Debbe; O'Connor, Teresia; Hughes, Sheryl; Diep, Cassandra; Baranowski, Janice C

    2015-04-01

    Increasing a parent's ability to influence a child's vegetable intake may require reducing the parent's use of ineffective vegetable parenting practices. The present study was designed to understand the psychosocial influences on ineffective vegetable parenting practices. A cross-sectional web-based survey was conducted to model use of ineffective vegetable parenting practices using validated scales from a Model of Goal Directed Vegetable Parenting Practices. The dependent variable was a composite ineffective vegetable parenting practices index. The independent variables included validated subscales of intention, habit, perceived barriers, desire, competence, autonomy, relatedness, attitudes, norms, perceived behavioural control and anticipated emotions. Models were analysed using block regression with backward deletion. Parents of 307 pre-school children (3-5 years old). Variables significantly positively related to ineffective vegetable parenting practices in order of relationship strength included habit of controlling vegetable practices (standardized β=0·349, P<0·0001) and desire (standardized β=0·117, P=0·025). Variables significantly negatively related to ineffective vegetable parenting practices in order of relationship strength included perceived behavioural control of negative parenting practices (standardized β=-0·215, P<0000), the habit of active child involvement in vegetable selection (standardized β=-0·142, P=0·008), anticipated negative parent emotional response to child vegetable refusal (standardized β=-0·133, P=0·009), autonomy (standardized β=-0·118, P=0.014), attitude about negative effects of vegetables (standardized β=-0·118, P=0·015) and descriptive norms (standardized β=-0·103, P=0·032). The model accounted for 40·5 % of the variance in use of ineffective vegetable parenting practices. The present study is the first report of psychometrically tested scales to predict use of ineffective vegetable parenting practices

  11. Predicting Use of Ineffective Vegetable Parenting Practices with the Model of Goal Directed Behavior

    PubMed Central

    Baranowski, Tom; Beltran, Alicia; Chen, Tzu-An; Thompson, Debbe; O’Connor, Teresia; Hughes, Sheryl; Diep, Cassandra; Baranowski, Janice C.

    2015-01-01

    Objective Increasing a parent’s ability to influence a child’s vegetable intake may require reducing the parent’s use of ineffective vegetable parenting practices. This study assessed the psychosocial influences on ineffective vegetable parenting practices. Design A cross-sectional web-based survey was conducted to model use of ineffective vegetable parenting practices using validated scales from a Model of Goal Directed Vegetable Parenting Practices. Setting The dependent variable was a composite ineffective vegetable parenting practices index. The independent variables included validated subscales of intention, habit, perceived barriers, desire, competence, autonomy, relatedness, attitudes, norms, perceived behavioral control, and anticipated emotions. Models were analyzed using block regression with backward deletion. Participants Parents of 307 preschool (3–5 yo) children. Results Variables significantly positively related to ineffective vegetable parenting practices in order of relationship strength included habit of controlling vegetable practices (standardized β=0.349, p<0.0001) and desire (standardized β=0.117, p=0.025). Variables significantly negatively related to ineffective vegetable parenting practices included perceived behavioral control of negative parenting practices (standardized β= −0.215, p<0.000), the habit of active child involvement in vegetable selection (standardized β= −0.142, p=0.008), anticipated negative parent emotional response to child vegetable refusal (standardized β= −0.133, p=0.009), autonomy (standardized β= −0.118, p=0.014), attitude about negative effects of vegetables (standardized β= −0.118, p=0.015), and descriptive norms (standardized β= −0.103, p=0.032). The model accounted for 40.5% of the variance in use of ineffective vegetable parenting practices. Conclusions This was the first report of psychometrically tested scales to predict use of ineffective vegetable parenting practices. Innovative

  12. Evaluation of unmanned aerial vehicle (UAV) imagery to model vegetation heights in Hulun Buir grassland ecosystem

    NASA Astrophysics Data System (ADS)

    Wang, D.; Xin, X.; Li, Z.

    2015-12-01

    Vertical vegetation structure in grassland ecosystem is needed to assess grassland health and monitor available forage for livestock and wildlife habitat. Traditional ground-based field methods for measuring vegetation heights are time consuming. Most emerging airborne remote sensing techniques capable of measuring surface and vegetation height (e.g., LIDAR) are too expensive to apply at broad scales. Aerial or spaceborne stereo imagery has the cost advantage for mapping height of tall vegetation, such as forest. However, the accuracy and uncertainty of using stereo imagery for modeling heights of short vegetation, such as grass (generally lower than 50cm) needs to be investigated. In this study, 2.5-cm resolution UAV stereo imagery are used to model vegetation heights in Hulun Buir grassland ecosystem. Strong correlations were observed (r > 0.9) between vegetation heights derived from UAV stereo imagery and those field-measured ones at individual and plot level. However, vegetation heights tended to be underestimated in the imagery especially for those areas with high vegetation coverage. The strong correlations between field-collected vegetation heights and metrics derived from UAV stereo imagery suggest that UAV stereo imagery can be used to estimate short vegetation heights such as those in grassland ecosystem. Future work will be needed to verify the extensibility of the methods to other sites and vegetation types.

  13. Modeling of Beam Wave Pulse Propagation in Vegetation Using Transport Theory

    DTIC Science & Technology

    2005-07-31

    SUBTITLE 5. FUNDING NUMBERS Modeling of Beam Wave Pulse Propagation in Vegetation using Transport Theory DAAD190110- S S 6. AUTHOR(S) Gerald M. Whitman...real- time modeling ( of interest to the soldier in the field), three new approximate theories for beam wave propagation in vegetation were developed and...Enclosure 1 MODELING OF BEAM WAVE PULSE PROPAGATION IN VEGETATION USING TRANSPORT THEORY By Gerald M. Whitman Felix K. Schwering Michael Yu-Chi Wu DISB

  14. Uncertainties of Nitrogen Fixation in a Dynamic Global Vegetation Model

    NASA Astrophysics Data System (ADS)

    Steinkamp, Joerg; Werner, Christian; Weber, Bettina; Hickler, Thomas

    2015-04-01

    Nitrogen is an essential nutrient for life on earth. However, most of it is in the form of dinitrogen (N2) unutilizable to life and only few organisms are able to break the triple bond, fix the nitrogen and thus make it available for cycling in the biosphere through "fixation". In most state-of-the-art dynamic global vegetation models (DGVMs) including a nitrogen cycle, N fixation is simulated by the Cleveland et al. (1999) algorithm (O-CN, LPJ-GUESS, CLM), that correlates annual N fixation to evapotranspiration rates or net primary production. Nevertheless, this algorithm has two major uncertainties, which are investigated by us: 1. The algorithm is based on annual fixation rates that are then applied uniformly throughout the year. However, in nature nitrogen fixation is an expensive process, which occurs only under favorable conditions. Here we compare the annual fixation values evenly distributed over the year with daily-derived fixation values based on a modified version of the Cleveland algorithm. We postulate that in higher latitudinal regions with seasonal climate as well as in regions with a distinct dry/wet season, modeled growth is enhanced by daily derived values compared to evenly distributed values, whereas in tropical regions hardly any difference will be visible. 2. One distinguishes between symbiotic and unsymbiotic nitrogen fixation, where the first one is associated with higher plants as symbionts supplying the fixers with carbohydrates, whereas the second, unsymbiotic is performed by so-called cryptogamic covers (CC). We found that the fixation by CC is underrepresented by the Cleveland algorithm, and a correction thus leads to enhanced growth in forested regions of higher latitudes that feature substantial CC fractions. Overall, the improvements of the algorithm proposed by us are expected to better reflect the reality of nitrogen fixation and cause an increased growth of vegetation, especially in higher northern latitudes.

  15. Effect of ground cover vegetation on the abundance and diversity of beneficial arthropods in citrus orchards.

    PubMed

    Silva, E B; Franco, J C; Vasconcelos, T; Branco, M

    2010-08-01

    The effect of ground cover upon the communities of beneficial arthropods established in the canopy of lemon trees was investigated, by comparing three ground-cover management treatments applied: RV, resident vegetation; S, sowed selected species; and BS, bare soil by controlling weeds with herbicide. Over two consecutive years, arthropod communities in the tree canopy were sampled periodically by beating and suction techniques. Significantly higher numbers of beneficial arthropods were found in the RV and S treatments in comparison with bare soil. Spiders and parasitoid wasps were the two most common groups, representing, respectively, 70% and 19% of all catches in beating samples and 33% and 53% in suction samples. For the RV and S treatments, significant seasonal deviations from the bare soil treatment were observed using principal response curves. Similar seasonal patterns were observed over the two years. The RV and S treatments showed significant positive deviations from the BS treatment in late spring and summer, accounted for the higher numbers of parasitoid wasps, coccinelids and lacewings present. By contrast, the seasonal deviations observed for the spider community differed from those of the remaining arthropods. During late winter and early spring, the RV and S treatments presented a higher abundance of spiders in the tree canopy, in comparison with bare soil, whereas in the summer significantly more spiders were found in the bare soil treatment. Spider movements between tree canopy and ground vegetation layers may justify this result.

  16. Bioclimatic distribution of vegetation for general circulation model studies

    NASA Technical Reports Server (NTRS)

    Prentice, Katharine Culbertson

    1990-01-01

    Four global bioclimatic schemes which qualify climates on the basis of the distribution of vegetation, including the Holdridge (1947), Thornthwaite (1948), Koeppen (1936), and Troll and Paffen (1964) schemes, were applied to two global climate data sets to produce maps of global vegetation distribution: the Rand set described by Schutz and Gates (1971, 1973, and 1974) and the Shea (1986) data set. The results show that only 38 to 40 percent of the observed land surface, mapped as 31 vegetation types, could be replicated by applying the four schemes to these data sets. The simulations were significantly improved by further subdividing and regrouping the climates defined by the schemes and by regrouping the observed vegetation types. With these alterations, 77 percent of the predicted vegetative landscape coresponded with the observed distribution of vegetation.

  17. Bioclimatic distribution of vegetation for general circulation model studies

    NASA Technical Reports Server (NTRS)

    Prentice, Katharine Culbertson

    1990-01-01

    Four global bioclimatic schemes which qualify climates on the basis of the distribution of vegetation, including the Holdridge (1947), Thornthwaite (1948), Koeppen (1936), and Troll and Paffen (1964) schemes, were applied to two global climate data sets to produce maps of global vegetation distribution: the Rand set described by Schutz and Gates (1971, 1973, and 1974) and the Shea (1986) data set. The results show that only 38 to 40 percent of the observed land surface, mapped as 31 vegetation types, could be replicated by applying the four schemes to these data sets. The simulations were significantly improved by further subdividing and regrouping the climates defined by the schemes and by regrouping the observed vegetation types. With these alterations, 77 percent of the predicted vegetative landscape coresponded with the observed distribution of vegetation.

  18. Using Simpson’s diversity index to examine multidimensional models of diversity in health professions education

    PubMed Central

    McLaughlin, Gerald W.; McLaughlin, Josetta S.; White, Carla Y.

    2016-01-01

    Objectives This study explored new models of diversity for health professions education that incorporate multiple attributes and examined differences in diversity based on urbanicity, geographic region, and institutional structure. Methods Simpson’s Diversity Index was used to develop race, gender, and interprofessional diversity indices for health professions schools in the United States (N = 318). Sullivan’s extension was used to develop a composite diversity index that incorporated multiple individual attributes for each school. Pearson’s r was used to investigate correlations between continuous variables. ANOVA and independent t-tests were used to compare groups based on urbanicity, geographic region, and Basic Carnegie Classification. Results Mean (SD) for race, gender, and interprofessional  diversity indices were 0.36(0.17), 0.45(0.07), and 0.22(0.27) respectively. All correlations between the three indices were weak. The composite diversity index for this sample was 0.34(0.13). Significant differences in diversity were found between institutions based on urbanicity, Basic Carnegie Classification, and geographic region. Conclusions Multidimensional models provide support for expanding measures of diversity to include multiple characteristics and attributes. The approach demonstrated in this study enables institutions to complement and extend traditional measures of diversity as a means of providing evidence for decision-making and progress towards institutional initiatives. PMID:26724917

  19. Using Simpson's diversity index to examine multidimensional models of diversity in health professions education.

    PubMed

    McLaughlin, Jacqueline E; McLaughlin, Gerald W; McLaughlin, Josetta S; White, Carla Y

    2016-01-03

    This study explored new models of diversity for health professions education that incorporate multiple attributes and examined differences in diversity based on urbanicity, geographic region, and institutional structure. Simpson's Diversity Index was used to develop race, gender, and interprofessional diversity indices for health professions schools in the United States (N = 318). Sullivan's extension was used to develop a composite diversity index that incorporated multiple individual attributes for each school. Pearson's r was used to investigate correlations between continuous variables. ANOVA and independent t-tests were used to compare groups based on urbanicity, geographic region, and Basic Carnegie Classification. Mean (SD) for race, gender, and interprofessional diversity indices were 0.36(0.17), 0.45(0.07), and 0.22(0.27) respectively. All correlations between the three indices were weak. The composite diversity index for this sample was 0.34(0.13). Significant differences in diversity were found between institutions based on urbanicity, Basic Carnegie Classification, and geographic region. Multidimensional models provide support for expanding measures of diversity to include multiple characteristics and attributes. The approach demonstrated in this study enables institutions to complement and extend traditional measures of diversity as a means of providing evidence for decision-making and progress towards institutional initiatives.

  20. Comparing biodiversity effects among ecosystem engineers of contrasting strength: macrofauna diversity in Zostera noltii and Spartina anglica vegetations

    NASA Astrophysics Data System (ADS)

    Bouma, Tjeerd J.; Ortells, Victor; Ysebaert, Tom

    2009-03-01

    Whereas it is well known that ecosystem engineers can have a large influence on biodiversity, underlying mechanisms are still not fully clear. We try to enhance insight by comparing biodiversity effects of two neighboring intertidal, clonal, ecosystem engineering plant species that modify the physical environmental parameters in a similar way, but with a different magnitude. Macrobenthic assemblages were compared between meadows of the seagrass Zostera noltii, small patches (≤0.5 m Ø) and large areas (≫5 m Ø) of the emergent halophyte Spartina anglica and the surrounding bare tidal mudflat (control). Multivariate analyses revealed that the mudflat benthic assemblage and Zostera meadow assemblage showed highest similarities, whereas the Spartina marsh assemblage showed the highest dissimilarity with these two areas. Whereas the descriptive nature of our study limits interpretation of the data, some clear patterns were observed. For all vegetated areas, species diversity was lower compared to the unvegetated mudflat, and we observed a strong shift from endo- towards epibenthic species, suggesting that increased above-ground habitat complexity may be a main driving process in our system. As there were no clear patterns related to feeding types, food availability/productivity appeared to be of minor importance in structuring the benthic assemblages. Nevertheless, animals were in general smaller in vegetated areas. Patchiness had a distinct positive effect on biodiversity.

  1. Epigenetic Diversity of Clonal White Poplar (Populus alba L.) Populations: Could Methylation Support the Success of Vegetative Reproduction Strategy?

    PubMed

    Guarino, Francesco; Cicatelli, Angela; Brundu, Giuseppe; Heinze, Berthold; Castiglione, Stefano

    2015-01-01

    The widespread poplar populations of Sardinia are vegetatively propagated and live in different natural environments forming large monoclonal stands. The main goals of the present study were: i) to investigate/measure the epigenetic diversity of the poplar populations by determining their DNA methylation status; ii) to assess if and how methylation status influences population clustering; iii) to shed light on the changes that occur in the epigenome of ramets of the same poplar clone. To these purposes, 83 white poplar trees were sampled at different locations on the island of Sardinia. Methylation sensitive amplified polymorphism analysis was carried out on the genomic DNA extracted from leaves at the same juvenile stage. The study showed that the genetic biodiversity of poplars is quite limited but it is counterbalanced by epigenetic inter-population molecular variability. The comparison between MspI and HpaII DNA fragmentation profiles revealed that environmental conditions strongly influence hemi-methylation of the inner cytosine. The variable epigenetic status of Sardinian white poplars revealed a decreased number of population clusters. Landscape genetics analyses clearly demonstrated that ramets of the same clone were differentially methylated in relation to their geographic position. Therefore, our data support the notion that studies on plant biodiversity should no longer be restricted to genetic aspects, especially in the case of vegetatively propagated plant species.

  2. Mapping, Monitoring and Modeling Submersed Aquatic Vegetation Species and Communities

    NASA Astrophysics Data System (ADS)

    Hartis, Brett Michael

    Aquatic macrophyte communities are critically important habitat species in aquatic systems worldwide. None are more important than those found beneath the water's surface, commonly referred to as submersed aquatic vegetation (SAV). Although vital to such systems, many native submersed plants have shown near irreversible declines in recent decades as water quality impairment, habitat destruction, and encroachment by invasive species have increased. In the past, aquatic plant science has emphasized the restoration and protection of native species and the management of invasive species. Comparatively little emphasis has been directed toward adequately mapping and monitoring these resources to track their viability over time. Modeling the potential intrusion of certain invasive plant species has also been given little attention, likely because aquatic systems in general can be difficult to assess. In recent years, scientists and resource managers alike have begun paying more attention to mapping SAV communities and to address the spread of invasive species across various regions. This research attempts to provide new, cutting-edge techniques to improve SAV mapping and monitoring efforts in coastal regions, at both community and individual species levels, while also providing insights about the establishment potential of Hydrilla verticillata, a noxious, highly invasive submersed plant. Technological advances in satellite remote sensing, interpolation and spatial analysis in geographic information systems, and state-of-the-art climate envelope modeling techniques were used to further assess the dynamic nature of SAV on various scales. This work contributes to the growing science of mapping, monitoring, and modeling of SAV

  3. Uncertainty analysis of vegetation distribution in the northern high latitudes during the 21st century with a dynamic vegetation model.

    PubMed

    Jiang, Yueyang; Zhuang, Qianlai; Schaphoff, Sibyll; Sitch, Stephen; Sokolov, Andrei; Kicklighter, David; Melillo, Jerry

    2012-03-01

    This study aims to assess how high-latitude vegetation may respond under various climate scenarios during the 21st century with a focus on analyzing model parameters induced uncertainty and how this uncertainty compares to the uncertainty induced by various climates. The analysis was based on a set of 10,000 Monte Carlo ensemble Lund-Potsdam-Jena (LPJ) simulations for the northern high latitudes (45(o)N and polewards) for the period 1900-2100. The LPJ Dynamic Global Vegetation Model (LPJ-DGVM) was run under contemporary and future climates from four Special Report Emission Scenarios (SRES), A1FI, A2, B1, and B2, based on the Hadley Centre General Circulation Model (GCM), and six climate scenarios, X901M, X902L, X903H, X904M, X905L, and X906H from the Integrated Global System Model (IGSM) at the Massachusetts Institute of Technology (MIT). In the current dynamic vegetation model, some parameters are more important than others in determining the vegetation distribution. Parameters that control plant carbon uptake and light-use efficiency have the predominant influence on the vegetation distribution of both woody and herbaceous plant functional types. The relative importance of different parameters varies temporally and spatially and is influenced by climate inputs. In addition to climate, these parameters play an important role in determining the vegetation distribution in the region. The parameter-based uncertainties contribute most to the total uncertainty. The current warming conditions lead to a complexity of vegetation responses in the region. Temperate trees will be more sensitive to climate variability, compared with boreal forest trees and C3 perennial grasses. This sensitivity would result in a unanimous northward greenness migration due to anomalous warming in the northern high latitudes. Temporally, boreal needleleaved evergreen plants are projected to decline considerably, and a large portion of C3 perennial grass is projected to disappear by the end of

  4. Uncertainty analysis of vegetation distribution in the northern high latitudes during the 21st century with a dynamic vegetation model

    PubMed Central

    Jiang, Yueyang; Zhuang, Qianlai; Schaphoff, Sibyll; Sitch, Stephen; Sokolov, Andrei; Kicklighter, David; Melillo, Jerry

    2012-01-01

    This study aims to assess how high-latitude vegetation may respond under various climate scenarios during the 21st century with a focus on analyzing model parameters induced uncertainty and how this uncertainty compares to the uncertainty induced by various climates. The analysis was based on a set of 10,000 Monte Carlo ensemble Lund-Potsdam-Jena (LPJ) simulations for the northern high latitudes (45oN and polewards) for the period 1900–2100. The LPJ Dynamic Global Vegetation Model (LPJ-DGVM) was run under contemporary and future climates from four Special Report Emission Scenarios (SRES), A1FI, A2, B1, and B2, based on the Hadley Centre General Circulation Model (GCM), and six climate scenarios, X901M, X902L, X903H, X904M, X905L, and X906H from the Integrated Global System Model (IGSM) at the Massachusetts Institute of Technology (MIT). In the current dynamic vegetation model, some parameters are more important than others in determining the vegetation distribution. Parameters that control plant carbon uptake and light-use efficiency have the predominant influence on the vegetation distribution of both woody and herbaceous plant functional types. The relative importance of different parameters varies temporally and spatially and is influenced by climate inputs. In addition to climate, these parameters play an important role in determining the vegetation distribution in the region. The parameter-based uncertainties contribute most to the total uncertainty. The current warming conditions lead to a complexity of vegetation responses in the region. Temperate trees will be more sensitive to climate variability, compared with boreal forest trees and C3 perennial grasses. This sensitivity would result in a unanimous northward greenness migration due to anomalous warming in the northern high latitudes. Temporally, boreal needleleaved evergreen plants are projected to decline considerably, and a large portion of C3 perennial grass is projected to disappear by the end of

  5. SOSlope: a new slope stability model for vegetated hillslopes

    NASA Astrophysics Data System (ADS)

    Cohen, D.; Schwarz, M.

    2016-12-01

    Roots contribute to increase soil strength but forces mobilized by roots depend on soil relative displacement. This effect is not included in models of slope stability. Here we present a new numerical model of shallow landslides for vegetated hillslopes that uses a strain-step loading approach for force redistributions within a soil mass including the effects of root strength in both tension and compression. The hillslope is discretized into a two-dimensional array of blocks connected by bonds. During a rainfall event the blocks's mass increases and the soil shear strength decreases. At each time step, we compute a factor of safety for each block. If the factor of safety of one or more blocks is less than one, those blocks are moved in the direction of the local active force by a predefined amount and the factor of safety is recalculated for all blocks. Because of the relative motion between blocks that have moved and those that remain stationary, mechanical bond forces between blocks that depend on relative displacement change, modifying the force balance. This relative motion triggers instantaneous force redistributions across the entire hillslope similar to a self-organized critical system. Looping over blocks and moving those that are unstable is repeated until all blocks are stable and the system reaches a new equilibrium, or, some blocks have failed causing a landslide. Spatial heterogeneity of vegetation is included by computing the root density and distribution as a function of distance form trees. A simple subsurface hydrological model based on dual permeability concepts is used to compute the temporal evolution of water content, pore-water pressure, suction stress, and soil shear strength. Simulations for a conceptual slope indicates that forces mobilized in tension and compression both contribute to the stability of the slope. However, the maximum tensional and compressional forces imparted by roots do not contribute simultaneously to the stability of

  6. Diversity modelling for electrical power system simulation

    NASA Astrophysics Data System (ADS)

    Sharip, R. M.; Abu Zarim, M. A. U. A.

    2013-12-01

    This paper considers diversity of generation and demand profiles against the different future energy scenarios and evaluates these on a technical basis. Compared to previous studies, this research applied a forecasting concept based on possible growth rates from publically electrical distribution scenarios concerning the UK. These scenarios were created by different bodies considering aspects such as environment, policy, regulation, economic and technical. In line with these scenarios, forecasting is on a long term timescale (up to every ten years from 2020 until 2050) in order to create a possible output of generation mix and demand profiles to be used as an appropriate boundary condition for the network simulation. The network considered is a segment of rural LV populated with a mixture of different housing types. The profiles for the 'future' energy and demand have been successfully modelled by applying a forecasting method. The network results under these profiles shows for the cases studied that even though the value of the power produced from each Micro-generation is often in line with the demand requirements of an individual dwelling there will be no problems arising from high penetration of Micro-generation and demand side management for each dwellings considered. The results obtained highlight the technical issues/changes for energy delivery and management to rural customers under the future energy scenarios.

  7. Incorporating grassland management in a global vegetation model

    NASA Astrophysics Data System (ADS)

    Chang, Jinfeng; Viovy, Nicolas; Vuichard, Nicolas; Ciais, Philippe; Wang, Tao; Cozic, Anne; Lardy, Romain; Graux, Anne-Isabelle; Klumpp, Katja; Martin, Raphael; Soussana, Jean-François

    2013-04-01

    Grassland is a widespread vegetation type, covering nearly one-fifth of the world's land surface (24 million km2), and playing a significant role in the global carbon (C) cycle. Most of grasslands in Europe are cultivated to feed animals, either directly by grazing or indirectly by grass harvest (cutting). A better understanding of the C fluxes from grassland ecosystems in response to climate and management requires not only field experiments but also the aid of simulation models. ORCHIDEE process-based ecosystem model designed for large-scale applications treats grasslands as being unmanaged, where C / water fluxes are only subject to atmospheric CO2 and climate changes. Our study describes how management of grasslands is included in the ORCHIDEE, and how management affects modeled grassland-atmosphere CO2 fluxes. The new model, ORCHIDEE-GM (Grassland Management) is capable with a management module inspired from a grassland model (PaSim, version 5.0), of accounting for two grassland management practices (cutting and grazing). The evaluation of the results of ORCHIDEE-GM compared with those of ORCHIDEE at 11 European sites equipped with eddy covariance and biometric measurements, show that ORCHIDEE-GM can capture realistically the cut-induced seasonal variation in biometric variables (LAI: Leaf Area Index; AGB: Aboveground Biomass) and in CO2 fluxes (GPP: Gross Primary Productivity; TER: Total Ecosystem Respiration; and NEE: Net Ecosystem Exchange). But improvements at grazing sites are only marginal in ORCHIDEE-GM, which relates to the difficulty in accounting for continuous grazing disturbance and its induced complex animal-vegetation interactions. Both NEE and GPP on monthly to annual timescales can be better simulated in ORCHIDEE-GM than in ORCHIDEE without management. At some sites, the model-observation misfit in ORCHIDEE-GM is found to be more related to ill-constrained parameter values than to model structure. Additionally, ORCHIDEE-GM is able to simulate

  8. Effects of tourism and topography on vegetation diversity in the subalpine meadows of the Dongling Mountains of Beijing, China.

    PubMed

    Zhang, Jin-Tun; Xiang, ChunLing; Li, Min

    2012-02-01

    Subalpine meadows in the Dongling Mountains (located at E115º26'-115º40', N40º00'-40º05') of Beijing, China are important for tourism and the provision of ecosystem services. However, because of poor management serious degradation has occurred on these subalpine meadows. The aim of this paper is to present a quantitative analysis of effects of tourism disturbance and topography on the status and diversity of montane meadow communities and to provide direction for improved management. Sixty quadrats of 2 × 2 m(2) along 10 transects were set up to collect data on site characteristics and vegetation status. The relationships between community composition and structure, species diversity, and tourism disturbance and topographic variables were analyzed by multivariate methods (TWINSPAN and CCA). The results showed that eight meadow communities were identified by TWINSPAN. Most of them were seriously degraded. The first CCA axis identified an elevation and tourism disturbance intensity gradient, which illustrated that tourism disturbance and elevation were most important factors influencing meadow types, composition and structure. Some resistant species and response species to tourism disturbance were identified and can be used as indicator species of tourism disturbance. Species richness, heterogeneity and evenness were closely related to tourism disturbance and elevation. It is concluded that tourism disturbance must be controlled to enable grassland rehabilitation to occur in the meadows. Measures of effective management of the meadows were discussed.

  9. The effect of vegetation on pesticide dissipation from ponded treatment wetlands: quantification using a simple model.

    PubMed

    Rose, Michael T; Crossan, Angus N; Kennedy, Ivan R

    2008-07-01

    Field data shows that plants accelerate pesticide dissipation from aquatic systems by increasing sedimentation, biofilm contact and photolysis. In this study, a graphical model was constructed and calibrated with site-specific and supplementary data to describe the loss of two pesticides, endosulfan and fluometuron, from a vegetated and a non-vegetated pond. In the model, the major processes responsible for endosulfan dissipation were alkaline hydrolysis and sedimentation, with the former process being reduced by vegetation and the latter enhanced. Fluometuron dissipation resulted primarily from biofilm reaction and photolysis, both of which were increased by vegetation. Here, greater photolysis under vegetation arose from faster sedimentation and increased light penetration, despite shading. Management options for employing constructed wetlands to polish pesticide-contaminated agricultural runoff are discussed. The lack of easily fulfilled sub-models and data describing the effect of aquatic vegetation on water chemistry and sedimentation is also highlighted.

  10. A gradient model of vegetation and climate utilizing NOAA satellite imagery. Phase 1: Texas transect

    NASA Technical Reports Server (NTRS)

    Greegor, D.; Norwine, J. (Principal Investigator)

    1981-01-01

    A climatological model/variable termed the sponge (a measure of moisture availability based on daily temperature maxima and minima, and precipitation) was tested for potential biogeograhic, ecological, and agro-climatological applications. Results, depicted in tabular and graphic form, suggest that, as generalized climatic index, sponge is particularly appropriate for large-area and global vegetation monitoring. The feasibility of utilizing NOAA/AVHRR data for vegetation classification was investigated and a vegetation gradient model that utilizes sponge and AVHRR data was initiated. Along an east-west Texas gradient, vegetation, sponge, and AVHRR pixel data (channels 1 and 2) were obtained for 12 locations. The normalized difference values for the AVHRR data when plotted against vegetation characteristics (biomass, net productivity, leaf area) and sponge values along the Texas gradient suggest that a multivariate gradient model incorporating AVHRR and sponge data may indeed be useful in global vegetation stratification and monitoring.

  11. The diversity pyramid: an organizational model to structure diversity recruitment and retention in nursing programs.

    PubMed

    Rosenberg, Lisa; O'Rourke, Marilyn E

    2011-10-01

    The literature on increasing the diversity of individuals who enter and practice the nursing profession comes with sound argument, yet we have seen only modest gains in diversification over the past 10 years. This article addresses how to develop a sustainable program to increase the recruitment and retention of underrepresented students. The diversity pyramid is suggested as a conceptual planning model for increasing diversity that is matched to an institution and its resources. The foundation of the pyramid is an organizational commitment to attracting and retaining diverse students. The middle level addresses financial support for underrepresented students. From the top of the pyramid, one chooses appropriate media and relational tactics necessary to attract the underrepresented students a program seeks. All three elements of the pyramid-organizational commitment to diversity, significant financial support, and a targeted use of resources-play important and sequential roles in building a sustainable diversity initiative.

  12. SCHOOL-BASED PROMOTION OF FRUIT AND VEGETABLE CONSUMPTION IN MULTICULTURALLY DIVERSE, URBAN SCHOOLS

    PubMed Central

    BLOM-HOFFMAN, JESSICA

    2009-01-01

    Rates of childhood overweight1 have reached epidemic proportions (U.S. Department of Health and Human Services, 2001), and schools have been called on to play a role in the prevention of this medical condition. This article describes a multiyear health promotion effort—the Athletes in Service fruit and vegetable (F&V) promotion program—which is based on social learning theory for urban, elementary school children in kindergarten through third grade. Children participate in the program for a period of 3 years. The goals of the program are to increase opportunities for children to be more physically active during the school day and to help students increase their F&V consumption. This article describes the F&V promotion components of the program that were implemented in year 1, including implementation integrity and treatment acceptability data. Year 1 evaluation data demonstrated that the program is acceptable from the perspective of school staff and was implemented by school staff with high levels of integrity. Hallmarks of the program’s successful implementation and high acceptability include (a) having a school-based program champion; (b) designing the program to include low-cost, attractive, interactive materials; (c) including many school staff members to facilitate a culture of healthy eating in the school; and (d) spreading out implementation responsibilities among the multiple staff members so that each individual’s involvement is time efficient. PMID:19834582

  13. Importance and genetic diversity of vegetable-infecting tospoviruses in India.

    PubMed

    Kunkalikar, Suresh R; Poojari, Sudarsana; Arun, Bhanupriya M; Rajagopalan, Prem A; Chen, Tsung-Chi; Yeh, Shyi-Dong; Naidu, Rayapati A; Zehr, Usha B; Ravi, Kankanallu S

    2011-03-01

    A survey for Peanut bud necrosis virus (PBNV), Watermelon bud necrosis virus (WBNV), Capsicum chlorosis virus (CaCV), and Iris yellow spot virus (IYSV) was conducted between 2002 and 2009 in the major vegetable-growing areas in India. PBNV was documented widely in tomato and chili peppers in 14 states representing southern, north-western, north-eastern, and central regions and WBNV was predominantly detected in watermelons and cucurbits in all except north-eastern regions. In addition, the expanded host range of PBNV to watermelons and other cucurbits and WBNV to tomato and chili peppers was observed leading to natural mixed infection of the two viruses. IYSV was found in onion in southern, central, and north-eastern regions and CaCV in tomato and chili peppers in northern and southern regions, respectively. Phylogenetic analysis of the nucleocapsid gene revealed segregation of field isolates of PBNV and WBNV into two distinct subclades, whereas isolates of CaCV and IYSV each clustered into a single clade. A proposal for establishing WBNV as a distinct tospovirus species is made based on the molecular characterization of small- (S) and medium- (M) RNA segments.

  14. Biogeophysical feedbacks trigger shifts in the modelled vegetation-atmosphere system at multiple scales

    NASA Astrophysics Data System (ADS)

    Dekker, S. C.; de Boer, H. J.; Brovkin, V.; Fraedrich, K.; Wassen, M. J.; Rietkerk, M.

    2010-04-01

    Terrestrial vegetation influences climate by modifying the radiative-, momentum-, and hydrologic-balance. This paper contributes to the ongoing debate on the question whether positive biogeophysical feedbacks between vegetation and climate may lead to multiple equilibria in vegetation and climate and consequent abrupt regime shifts. Several modelling studies argue that vegetation-climate feedbacks at local to regional scales could be strong enough to establish multiple states in the climate system. An Earth Model of Intermediate Complexity, PlaSim, is used to investigate the resilience of the climate system to vegetation disturbance at regional to global scales. We hypothesize that by starting with two extreme initialisations of biomass, positive vegetation-climate feedbacks will keep the vegetation-atmosphere system within different attraction domains. Indeed, model integrations starting from different initial biomass distributions diverged to clearly distinct climate-vegetation states in terms of abiotic (precipitation and temperature) and biotic (biomass) variables. Moreover, we found that between these states there are several other steady states which depend on the scale of perturbation. From here global susceptibility maps were made showing regions of low and high resilience. The model results suggest that mainly the boreal and monsoon regions have low resiliences, i.e. instable biomass equilibria, with positive vegetation-climate feedbacks in which the biomass induced by a perturbation is further enforced. The perturbation did not only influence single vegetation-climate cell interactions but also caused changes in spatial patterns of atmospheric circulation due to neighbouring cells constituting in spatial vegetation-climate feedbacks. Large perturbations could trigger an abrupt shift of the system towards another steady state. Although the model setup used in our simulation is rather simple, our results stress that the coupling of feedbacks at multiple

  15. Modeling of the interactions between forest vegetation, disturbances, and sediment yields

    Treesearch

    Erkan Istanbulluoglu; David G. Tarboton; Robert T. Pack; Charles H. Luce

    2004-01-01

    The controls of forest vegetation, wildfires, and harvest vegetation disturbances on the frequency and magnitude of sediment delivery from a small watershed (~3.9 km2) in the Idaho batholith are investigated through numerical modeling. The model simulates soil development based on continuous bedrock weathering and the divergence of diffusive...

  16. Predicting landscape vegetation dynamics using state-and-transition simulation models

    Treesearch

    Colin J. Daniel; Leonardo. Frid

    2012-01-01

    This paper outlines how state-and-transition simulation models (STSMs) can be used to project changes in vegetation over time across a landscape. STSMs are stochastic, empirical simulation models that use an adapted Markov chain approach to predict how vegetation will transition between states over time, typically in response to interactions between succession,...

  17. A model for estimating understory vegetation response to fertilization and precipitation in loblolly pine plantations

    Treesearch

    Curtis L. VanderSchaaf; Ryan W. McKnight; Thomas R. Fox; H. Lee Allen

    2010-01-01

    A model form is presented, where the model contains regressors selected for inclusion based on biological rationale, to predict how fertilization, precipitation amounts, and overstory stand density affect understory vegetation biomass. Due to time, economic, and logistic constraints, datasets of large sample sizes generally do not exist for understory vegetation. Thus...

  18. Lidar based vegetation height models to quantify carbon stocks in Galveston saltmarshes

    NASA Astrophysics Data System (ADS)

    Kulawardhana, R. W.; Popescu, S. C.; Feagin, R. A.

    2012-12-01

    Concern over global climate change has stimulated much interest in identifying existing and potential carbon sinks. Wetland ecosystems are highly recognized for their high productivity and thus as major terrestrial carbon (C) sinks. The rapid decline in the extent and health of these wetland ecosystems has created a need for non-destructive methods for the study of their C dynamics. However, these biomass estimates are mostly based on vegetation structural properties, particularly based on vegetation height models. Hence, for better quantification of vegetation biomass and C estimates, the accuracy of vegetation height models derived using lidar data is of paramount importance. Yet, unlike in woody vegetation dominated ecosystems, the use of lidar in saltmarshes is limited due to several reasons: 1) relatively dense vegetation cover limits laser penetration affecting the accuracy of terrain and thus vegetation height estimates; and 2) relatively shorter vegetation demands high point density data with high vertical accuracy to capture relatively smaller differences between terrain and vegetation canopy surfaces. Thus, the use of lidar data to characterize saltmarsh vegetation community demands appropriate methodologies. Our overall objective in this study was to develop a methodology for deriving salt marsh vegetation height models using airborne lidar data. More specific objectives involved: (1) understanding the interaction between discrete-return airborne lidar data and marsh vegetation; (2) finding appropriate grid sizes for deriving terrain and vegetation height models; and (3) analyze lidar-derived surface accuracies by comparing estimates to field measurements. In this study, we used 1m point spacing airborne lidar data from Federal Emergency Management Agency (FEMA) program to derive vegetation height models (VHM) for Spartina alterniflora saltmarshes in Galveston, Texas. We first derived digital terrain models (DEMs) and verified their vertical accuracy

  19. Vegetation fires, absorbing aerosols and smoke plume characteristics in diverse biomass burning regions of Asia

    NASA Astrophysics Data System (ADS)

    Prasad Vadrevu, Krishna; Lasko, Kristofer; Giglio, Louis; Justice, Chris

    2015-10-01

    In this study, we explored the relationships between the satellite-retrieved fire counts (FC), fire radiative power (FRP) and aerosol indices using multi-satellite datasets at a daily time-step covering ten different biomass burning regions in Asia. We first assessed the variations in MODIS-retrieved aerosol optical depths (AOD’s) in agriculture, forests, plantation and peat land burning regions and then used MODIS FC and FRP (hereafter FC/FRP) to explain the variations in AOD characteristics. Results suggest that tropical broadleaf forests in Laos burn more intensively than the other vegetation fires. FC/FRP-AOD correlations in different agricultural residue burning regions did not exceed 20% whereas in forest regions they reached 40%. To specifically account for absorbing aerosols, we used Ozone Monitoring Instrument-derived aerosol absorption optical depth (AAOD) and UV aerosol index (UVAI). Results suggest relatively high AAOD and UVAI values in forest fires compared with peat and agriculture fires. Further, FC/FRP could explain a maximum of 29% and 53% of AAOD variations, whereas FC/FRP could explain at most 33% and 51% of the variation in agricultural and forest biomass burning regions, respectively. Relatively, UVAI was found to be a better indicator than AOD and AAOD in both agriculture and forest biomass burning plumes. Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations data showed vertically elevated aerosol profiles greater than 3.2-5.3 km altitude in the forest fire plumes compared to 2.2-3.9 km and less than 1 km in agriculture and peat-land fires, respectively. We infer the need to assimilate smoke plume height information for effective characterization of pollutants from different sources.

  20. Modeling the Effect of Vegetation on Passive Microwave Remote Sensing of Soil Moisture

    NASA Technical Reports Server (NTRS)

    Liu, Y. P.; Inguva, R.; Crosson, W. L.; Coleman, T. L.; Laymon, C.; Fahsi, A.

    1998-01-01

    The effect of vegetation on passive microwave remote sensing of soil moisture is studied. The radiative transfer modeling work of Njoku and Kong is applied to a stratified medium of which the upper layer is treated as a layer of vegetation. An effective dielectric constant for this vegetation layer is computed using estimates of the dielectric constant of individual components of the vegetation layer. The horizontally-polarized brightness temperature is then computed as a function of the incidence angle. Model predictions are used to compare with the data obtained in the Huntsville '96, remote sensing of soil moisture experiment, and with predictions obtained using a correction procedure of Jackson and Schmugge.

  1. Effects of heterogeneous wind fields and vegetation composition on modeled estimates of pollen source area

    NASA Astrophysics Data System (ADS)

    Burke, K. D.; Goring, S. J.; Williams, J. W.; Holloway, T.

    2015-12-01

    Fossil pollen records from lakes, bogs, and small hollows offer the main source of information about vegetation responses to climate change and land use over timescales of decades to millennia. Millions of pollen grains are released from individual trees each year, and are transported by wind before settling out of the atmosphere. Reconstructing past vegetation from sedimentary pollen records, however, requires careful modeling of pollen production, transport, and deposition. The atmosphere is turbulent, and regional wind patterns shift from day to day. In accordance with this, it is necessary for pollen transport models to adequately account for variable, non-uniform wind patterns and vegetation heterogeneity. Using a simulation approach, with both simulated vegetation patterns and vegetation gradients, as well as simulated wind fields, we show the inconsistency in pollen loading proportions and local vegetation proportions when non-uniform wind patterns are incorporated. Vegetation upwind from the lake is over-represented due to the increased prevalence of winds transporting pollen from that area. The inclusion of North American Regional Reanalysis (NARR) wind records affirms this finding. Of the lake sites explored in this study, none had uniform wind patterns. The use of a settlement-era gridded vegetation dataset, compiled by the PalEON project and based on Public Land Survey System (PLSS) records allows us to model pollen source area with realistic vegetation heterogeneity. Due to differences in productivity, pollen fall speeds, and neighboring vegetation, there exist patterns of vegetation that may be poorly characterized due to over/under representation of different taxa. Better understanding these differences in representation allows for more accurate reconstruction of historical vegetation, and pollen-vegetation relationships.

  2. Use of dynamic soil-vegetation models to assess impacts of nitrogen deposition on plant species composition: an overview.

    PubMed

    De Vries, W; Wamelink, G W W; Van Dobben, H; Kros, J; Reinds, G J; Mol-Dijkstra, J P; Smart, S M; Evans, C D; Rowe, E C; Belyazid, S; Sverdrup, H U; Van Hinsberg, A; Posch, M; Hettelingh, J-P; Spranger, T; Bobbink, R

    2010-01-01

    Field observations and experimental data of effects of nitrogen (N) deposition on plant species diversity have been used to derive empirical critical N loads for various ecosystems. The great advantage of such an approach is the inclusion of field evidence, but there are also restrictions, such as the absence of explicit criteria regarding significant effects on the vegetation, and the impossibility to predict future impacts when N deposition changes. Model approaches can account for this. In this paper, we review the possibilities of static and dynamic multispecies models in combination with dynamic soil-vegetation models to (1) predict plant species composition as a function of atmospheric N deposition and (2) calculate critical N loads in relation to a prescribed protection level of the species composition. The similarities between the models are presented, but also several important differences, including the use of different indicators for N and acidity and the prediction of individual plant species vs. plant communities. A summary of the strengths and weaknesses of the various models, including their validation status, is given. Furthermore, examples are given of critical load calculations with the model chains and their comparison with empirical critical N loads. We show that linked biogeochemistry-biodiversity models for N have potential for applications to support European policy to reduce N input, but the definition of damage thresholds for terrestrial biodiversity represents a major challenge. There is also a clear need for further testing and validation of the models against long-term monitoring or long-term experimental data sets and against large-scale survey data. This requires a focused data collection in Europe, combing vegetation descriptions with variables affecting the species diversity, such as soil acidity, nutrient status and water availability. Finally, there is a need for adaptation and upscaling of the models beyond the regions for which

  3. Site preparation burning to improve southern Appalachian pine-hardwood stands: vegetation composition and diversity of 13-year-old stands

    Treesearch

    Barton D. Clinton; J.M. Vose; W.T. Swank

    1993-01-01

    Stand restoration of low-quality, mixed pine-hardwood ecosystems containing a Kalmia Zatifolia L. dominated understory, through cutting, burning, and planting of Pinus strobus L., is common on xeric southern Appalachian forest sites. We examined the effects of this treatment on early vegetation composition and diversity. Four 13-year-old stands were examined. Two of...

  4. A population model of chaparral vegetation response to frequent wildfires.

    PubMed

    Lucas, Timothy A; Johns, Garrett; Jiang, Wancen; Yang, Lucie

    2013-12-01

    The recent increase in wildfire frequency in the Santa Monica Mountains (SMM) may substantially impact plant community structure. Species of Chaparral shrubs represent the dominant vegetation type in the SMM. These species can be divided into three life history types according to their response to wildfires. Nonsprouting species are completely killed by fire and reproduce by seeds that germinate in response to a fire cue, obligate sprouting species survive by resprouting from dormant buds in a root crown because their seeds are destroyed by fire, and facultative sprouting species recover after fire both by seeds and resprouts. Based on these assumptions, we developed a set of nonlinear difference equations to model each life history type. These models can be used to predict species survivorship under varying fire return intervals. For example, frequent fires can lead to localized extinction of nonsprouting species such as Ceanothus megacarpus while several facultative sprouting species such as Ceanothus spinosus and Malosma (Rhus) laurina will persist as documented by a longitudinal study in a biological preserve in the SMM. We estimated appropriate parameter values for several chaparral species using 25 years of data and explored parameter relationships that lead to equilibrium populations. We conclude by looking at the survival strategies of these three species of chaparral shrubs under varying fire return intervals and predict changes in plant community structure under fire intervals of short return. In particular, our model predicts that an average fire return interval of greater than 12 years is required for 50 % of the initial Ceanothus megacarpus population and 25 % of the initial Ceanothus spinosus population to survive. In contrast, we predict that the Malosma laurina population will have 90 % survivorship for an average fire return interval of at least 6 years.

  5. Inclusion of Additional Plant Species and Trait Information in Dynamic Vegetation Modeling of Arctic Tundra and Boreal Forest Ecosystem

    NASA Astrophysics Data System (ADS)

    Euskirchen, E. S.; Patil, V.; Roach, J.; Griffith, B.; McGuire, A. D.

    2015-12-01

    Dynamic vegetation models (DVMs) have been developed to model the ecophysiological characteristics of plant functional types in terrestrial ecosystems. They have frequently been used to answer questions pertaining to processes such as disturbance, plant succession, and community composition under historical and future climate scenarios. While DVMs have proved useful in these types of applications, it has often been questioned if additional detail, such as including plant dynamics at the species-level and/or including species-specific traits would make these models more accurate and/or broadly applicable. A sub-question associated with this issue is, 'How many species, or what degree of functional diversity, should we incorporate to sustain ecosystem function in modeled ecosystems?' Here, we focus on how the inclusion of additional plant species and trait information may strengthen dynamic vegetation modeling in applications pertaining to: (1) forage for caribou in northern Alaska, (2) above- and belowground carbon storage in the boreal forest and lake margin wetlands of interior Alaska, and (3) arctic tundra and boreal forest leaf phenology. While the inclusion of additional information generally proved valuable in these three applications, this additional detail depends on field data that may not always be available and may also result in increased computational complexity. Therefore, it is important to assess these possible limitations against the perceived need for additional plant species and trait information in the development and application of dynamic vegetation models.

  6. The role of canopy hydrological diversity and complexity on water balance and carbon sequestration during dry conditions: a modeling study

    NASA Astrophysics Data System (ADS)

    Lin, L.; Stewart, A.; Band, L. E.

    2016-12-01

    The importance and influence of forest to catchment hydrology have been well recognized. In the South Eastern U.S., Chapel Hill, NC, evapotranspiration by forest dominates almost 80% of the annual precipitation in long term average. Stomatal conductivity varies by tree species and its response to dry condition differently between evergreen and deciduous, and within their phonology groups. In this study, we simulated the catchment hydrology and forest ecosystem at a local catchment, Cane Creek, in the Chapel Hill triangle area using a spatially distributed, process-based hydro-ecological model, RHESSys. We incorporated characteristics of individual tree species to represent high hydrological diversity (e.g., maple, oak, pine), which has been modeled as either evergreen or deciduous (low hydrological diversity) in many studies. With tree species specifically modeled, we were able to investigate the role of tree species diversity and complexity on catchment hydrology. Local forest plant diversity, size, and density were provided by the U.S. Forest Services FIA, and tree species physiological parameters were obtained through researches at Duke Forest. High hydrological diversity canopy has higher water use and carbon sequestration than low hydrological diversity canopy. This result supports the optimality theory that emergent vegetation pattern in landscape maximizes ecosystem productivity and water use efficiency. Previous study emphasized this emergent pattern in terms of vegetation density along the hillslope gradient, and we further emphasized the emergent pattern in terms of hydrological diversity in this study.

  7. Modeling and analysis of vegetation-climate interactions using neutral networks and generalized logit models

    SciTech Connect

    Siegel, E.; Kandikar, M.; Dowlatabadi, H.

    1995-12-31

    The importance of biosphere-climate interactions for energy and moisture balances and major biogeochemical cycles is well recognized. Climate change is expected to alter the functioning and distribution of major ecosystems. These changes have been investigated using global vegetation transfer models.

  8. Remote Sensing of Vegetation Parameters for Modeling Coastal Marsh Response to Sea Level Rise

    NASA Astrophysics Data System (ADS)

    Byrd, K. B.; Windham-Myers, L.; Warzecha, B.; Crowe, R.; Vasey, M. C.; Ferner, M.

    2014-12-01

    Coastal planners are seeking ways to prepare for the potential impacts of future climate change, particularly sea level rise though management of future risks is complicated by uncertainty in the timing, distribution and extent of these impacts. Sea level rise impacts will be most evident at the regional level where decisions related to climate change adaptation including those related to land use planning and habitat management typically occur. To aid coastal managers with decision-making we are integrating remote sensing data with the marsh equilibrium model (MEM3) to project coastal marsh habitat response to future sea level rise. MEM3 is a 1-dimentional, calibrated Excel-based model that incorporates both physical and biological feedbacks to changing relative elevations. Modeled future elevations are then distributed at the regional scale with LiDAR DEMs to project changes to coastal habitats and dependent wildlife. Because plant biomass and structure influence both organic and inorganic accretion, MEM3 includes multiple vegetation input variables. Deriving these variables, including maximum and minimum elevations of marsh vegetation, peak aboveground biomass, and elevation at peak biomass from remote sensing will enable the model to have spatially variable inputs across sites. We are evaluating 30m Landsat 8 and 2m World View-2 (WV2) satellite data for mapping peak biomass at Rush Ranch, a highly diverse brackish marsh in the San Francisco Bay National Estuarine Research Reserve. The high spatial resolution of WV2 produces greater variability in plant reflectance at the pixel scale than Landsat 8. Initial results show the need for plant community-specific biomass models with WV2 to account for differences in plant structure and canopy architecture. When removing plots dominated by Salicornia pacifica and Lepidium latifolium, peak biomass is best estimated with an NDVI-type vegetation index based on WV2 near infrared bands 7 and 8 (R2 = 0.21, RMSE = 318 g/m2

  9. Metabolic model for diversity-generating biosynthesis

    PubMed Central

    Tianero, Ma. Diarey; Pierce, Elizabeth; Raghuraman, Shrinivasan; Sardar, Debosmita; McIntosh, John A.; Heemstra, John R.; Schonrock, Zachary; Covington, Brett C.; Maschek, J. Alan; Cox, James E.; Bachmann, Brian O.; Olivera, Baldomero M.; Ruffner, Duane E.; Schmidt, Eric W.

    2016-01-01

    A conventional metabolic pathway leads to a specific product. In stark contrast, there are diversity-generating metabolic pathways that naturally produce different chemicals, sometimes of great diversity. We demonstrate that for one such pathway, tru, each ensuing metabolic step is slower, in parallel with the increasing potential chemical divergence generated as the pathway proceeds. Intermediates are long lived and accumulate progressively, in contrast with conventional metabolic pathways, in which the first step is rate-limiting and metabolic intermediates are short-lived. Understanding these fundamental differences enables several different practical applications, such as combinatorial biosynthesis, some of which we demonstrate here. We propose that these principles may provide a unifying framework underlying diversity-generating metabolism in many different biosynthetic pathways. PMID:26831074

  10. Higher Ant Diversity in Native Vegetation Than in Stands of the Invasive Arundo, Arundo donax L., Along the Rio Grande Basin in Texas, USA.

    PubMed

    Osbrink, Weste LA; Goolsby, John A; Thomas, Don B; Mejorado, Alba; Showler, Allan T; Pérez De León, Adalberto

    2017-01-01

    Our hypothesis was that there will be greater ant biodiversity in heterogeneous native vegetation compared with Arundo stands. Changes in ant biodiversity due to Arundo invasion may be one of the ecological changes in the landscape that facilitates the invasion of cattle fever ticks from Mexico where they are endemic. Ants collected in pitfall traps were identified and compared between native vegetation and stands of Arundo, Arundo donax L., monthly for a year at 10 locations. A total of 82 752 ants representing 28 genera and 76 species were collected. More ants were collected in the native vegetation which also had greater species richness and biological diversity than ants collected from Arundo stands. It is suggested that the greater heterogeneous nature of native vegetation provided greater and more predictable nourishment in the form of nectars and more abundant arthropod prey when compared with Arundo stands.

  11. Diversity of insect galls associated with coastal shrub vegetation in Rio de Janeiro, Brazil.

    PubMed

    Carvalho-Fernandes, Sheila P; Ascendino, Sharlene; Maia, Valéria C; Couri, Márcia S

    2016-09-01

    Surveys in the coastal sandy plains (restingas) of Rio de Janeiro have shown a great richness of galls. We investigated the galling insects in two preserved restingas areas of Rio de Janeiro state: Parque Estadual da Costa do Sol and Reserva Particular do Patrimônio Natural Fazenda Caruara. The collections were done each two months, from June 2011 to May 2012. We investigated 38 points during 45 minutes each per collection. The galls were taken to the laboratory for rearing the insects. A total number of 151 insect galls were found in 82 plant species distributed into 34 botanic families. Most of the galls occurred on leaves and the plant families with the highest richness of galls were Myrtaceae and Fabaceae. All the six insect orders with galling species were found in this survey, where Cecidomyiidae (Diptera) was the main galler group. Hymenoptera and Thysanoptera were found as parasitoids and inquilines in 29 galls. The richness of galls in the surveyed areas reveals the importance of restinga for the composition and diversity of gall-inducing insect fauna.

  12. Responses of serpentine plants to pine invasion: Vegetation diversity and nickel accumulation in species with contrasting adaptive strategies.

    PubMed

    Selvi, Federico; Carrari, Elisa; Colzi, Ilaria; Coppi, Andrea; Gonnelli, Cristina

    2017-04-01

    Introduction of non-native trees is one of the major threats to ecosystem integrity and biodiversity. Stands of maritime pine (Pinus pinaster Ait.) introduced decades ago represent a threat to the specialized plant communities of serpentine outcrops in Italy. This study investigates the effects of such invasions at the community and species level, based on vegetation sampling in three selected sites with comparable environmental conditions. Pine cover caused a decrease of α-diversity by lowering the species evenness of the community, though species richness was not negatively affected. Compositional changes between the two habitats were significant but not clearly associated with a decrease in taxonomic distinctness in the pine stands. As many as nine indicator species were found in the open vegetation, along with the obligate endemics Odontarrhena bertolonii and Armeria denticulata. Both of them declined in the pine stands. Here, an increase in the phytoavailable nickel fraction was associated with a decrease in total nickel concentration in the soil, via mobilization of the metal caused by lowering of pH induced by the conifer litter. The nickel-hyperaccumulator O. bertolonii was able to maintain high metal concentrations in the shoots despite a decrease in root concentration, resulting in a higher shoot/root ratio in the pine stands (~20). Conversely, shoot/root ratio in the non-accumulator Plantago holosteum was <1 and not affected by the conifer, as well as its abundance in this anthropogenic habitat. Contrasting responses of the two species were likely due to their different sensitivity to modified light and soil conditions, whereas stability of shoot nickel-concentration in O. bertolonii did not support increased predation by natural enemies as one of the causes for its decline under the conifer. Progressive thinning of these stands is advocated to limit soil nickel mobilization and to restore a unique ecosystem with its endemic metallophytes.

  13. Diversity of Phytophthora Species from Declining Mediterranean Maquis Vegetation, including Two New Species, Phytophthora crassamura and P. ornamentata sp. nov.

    PubMed Central

    Scanu, Bruno; Linaldeddu, Benedetto T.; Deidda, Antonio; Jung, Thomas

    2015-01-01

    The Mediterranean basin is recognized as a global biodiversity hotspot accounting for more than 25,000 plant species that represent almost 10% of the world’s vascular flora. In particular, the maquis vegetation on Mediterranean islands and archipelagos constitutes an important resource of the Mediterranean plant diversity due to its high rate of endemism. Since 2009, a severe and widespread dieback and mortality of Quercus ilex trees and several other plant species of the Mediterranean maquis has been observed in the National Park of La Maddalena archipelago (northeast Sardinia, Italy). Infected plants showed severe decline symptoms and a significant reduction of natural regeneration. First studies revealed the involvement of the highly invasive wide-host range pathogen Phytophthora cinnamomi and several fungal pathogens. Subsequent detailed research led to a better understanding of these epidemics showing that multiple Phytophthora spp. were involved, some of them unknown to science. In total, nine Phytophthora species were isolated from rhizosphere soil samples collected from around symptomatic trees and shrubs including Asparagus albus, Cistus sp., Juniperus phoenicea, J. oxycedrus, Pistacia lentiscus and Rhamnus alaternus. Based on morphological characters, growth-temperature relations and sequence analysis of the ITS and cox1 gene regions, the isolates were identified as Phytophthora asparagi, P. bilorbang, P. cinnamomi, P. cryptogea, P. gonapodyides, P. melonis, P. syringae and two new Clade 6 taxa which are here described as P. crassamura sp. nov. and P. ornamentata sp. nov. Pathogenicity tests supported their possible involvement in the severe decline that is currently threatening the Mediterranean maquis vegetation in the La Maddalena archipelago. PMID:26649428

  14. Diversity of Phytophthora Species from Declining Mediterranean Maquis Vegetation, including Two New Species, Phytophthora crassamura and P. ornamentata sp. nov.

    PubMed

    Scanu, Bruno; Linaldeddu, Benedetto T; Deidda, Antonio; Jung, Thomas

    2015-01-01

    The Mediterranean basin is recognized as a global biodiversity hotspot accounting for more than 25,000 plant species that represent almost 10% of the world's vascular flora. In particular, the maquis vegetation on Mediterranean islands and archipelagos constitutes an important resource of the Mediterranean plant diversity due to its high rate of endemism. Since 2009, a severe and widespread dieback and mortality of Quercus ilex trees and several other plant species of the Mediterranean maquis has been observed in the National Park of La Maddalena archipelago (northeast Sardinia, Italy). Infected plants showed severe decline symptoms and a significant reduction of natural regeneration. First studies revealed the involvement of the highly invasive wide-host range pathogen Phytophthora cinnamomi and several fungal pathogens. Subsequent detailed research led to a better understanding of these epidemics showing that multiple Phytophthora spp. were involved, some of them unknown to science. In total, nine Phytophthora species were isolated from rhizosphere soil samples collected from around symptomatic trees and shrubs including Asparagus albus, Cistus sp., Juniperus phoenicea, J. oxycedrus, Pistacia lentiscus and Rhamnus alaternus. Based on morphological characters, growth-temperature relations and sequence analysis of the ITS and cox1 gene regions, the isolates were identified as Phytophthora asparagi, P. bilorbang, P. cinnamomi, P. cryptogea, P. gonapodyides, P. melonis, P. syringae and two new Clade 6 taxa which are here described as P. crassamura sp. nov. and P. ornamentata sp. nov. Pathogenicity tests supported their possible involvement in the severe decline that is currently threatening the Mediterranean maquis vegetation in the La Maddalena archipelago.

  15. ENSO Diversity in Climate Models: A Linear Inverse Modeling Approach

    NASA Astrophysics Data System (ADS)

    Capotondi, A.; Sardeshmukh, P. D.

    2013-12-01

    As emphasized in a large recent literature, ENSO events differ in the longitudinal location of the largest sea surface temperature (SST) anomalies along the equator. These differences in peak longitude are associated with different atmospheric teleconnections and global-scale impacts, whose large societal relevance makes it very important to understand the origin and predictability of the various ENSO 'flavors'. In this study we use Linear Inverse Modeling (LIM) to examine ENSO diversity in a 1000-year pre-industrial control integration of the National Center for Atmospheric Research (NCAR) Community Climate System Model version 4 (CCSM4). We choose a pre-industrial control integration for its multi-century duration, and also to examine ENSO diversity in the context of natural variability. The NCAR-CCSM4 has relatively realistic ENSO variability, and a rich spectrum of ENSO diversity, and is thus well suited for studying the origin of ENSO flavors. In particular, the relative frequency of events peaking in the eastern and central equatorial Pacific ('EP' versus 'CP') undergoes inter-decadal modulations in this 1000-yr run. By constructing separate LIMs for the EP and CP epochs, as well as for the entire simulation, we examine to what extent the dominance of a specific ENSO flavor can be attributed to changes in the system dynamics (i.e in the LIM's linear operator) or is merely due to noise. Results from this study provide insights into the predictability of different ENSO types, establish a baseline for assessing ENSO changes due to global warming, and help define new dynamically meaningful ENSO metrics for evaluating climate models.

  16. Using a Dynamic Global Vegetation Model to Simulate the Response of Vegetation to Warming at the Paleocene-Eocene Boundary

    NASA Astrophysics Data System (ADS)

    Shellito, C. J.; Sloan, L. C.

    2004-12-01

    A major turnover in benthic marine and terrestrial fauna marks the Initial Eocene Thermal Maximum (IETM) (~55Ma), a period of ~150 ky in which there was a rapid rise in deep sea and high latitude sea surface temperatures by 5-8C. Curiously, no major responses to this warming in the terrestrial floral record have been detected to date. Here, we present results from experiments examining the response of the global distribution of vegetation to changes in climate at the IETM using the NCAR Land Surface Model (LSM1.2) integrated with a dynamic global vegetation model (DGVM). DGVMs allow vegetation to respond to and interact with climate, and thus, provide a unique new method for addressing questions regarding feedbacks between the ecosystem and climate in Earth's past. However, there are a number of drawbacks to using these models that can affect interpretation of results. More specifically, these drawbacks involve uncertainties in the application of modern plant functional types to paleo-flora simulations, inaccuracies in the model climatology used to drive the DGVM, and lack of available detail regarding paleo-geography and paleo-soil type for use in model boundary conditions. For a better understanding of these drawbacks, we present results from a series of tests in the NCAR LSM-DGVM which examine (1) the effect of removing C4 grasses from the available plant functional types in the model; (2) model sensitivity to a change in soil texture; and (3), model sensitivity to a change in the value of pCO2 used in the photosynthetic rate equations. We consider our DGVM results for the IETM in light of output from these sensitivity experiments.

  17. Improved meteorology from an updated WRF/CMAQ modeling system with MODIS vegetation and albedo

    EPA Science Inventory

    Realistic vegetation characteristics and phenology from the Moderate Resolution Imaging Spectroradiometer (MODIS) products improve the simulation for the meteorology and air quality modeling system WRF/CMAQ (Weather Research and Forecasting model and Community Multiscale Air Qual...

  18. Improved meteorology from an updated WRF/CMAQ modeling system with MODIS vegetation and albedo

    EPA Science Inventory

    Realistic vegetation characteristics and phenology from the Moderate Resolution Imaging Spectroradiometer (MODIS) products improve the simulation for the meteorology and air quality modeling system WRF/CMAQ (Weather Research and Forecasting model and Community Multiscale Air Qual...

  19. Modelling Holocene peatland and permafrost dynamics with the LPJ-GUESS dynamic vegetation model

    NASA Astrophysics Data System (ADS)

    Chaudhary, Nitin; Miller, Paul A.; Smith, Benjamin

    2016-04-01

    Dynamic global vegetation models (DGVMs) are an important platform to study past, present and future vegetation patterns together with associated biogeochemical cycles and climate feedbacks (e.g. Sitch et al. 2008, Smith et al. 2001). However, very few attempts have been made to simulate peatlands using DGVMs (Kleinen et al. 2012, Tang et al. 2015, Wania et al. 2009a). In the present study, we have improved the peatland dynamics in the state-of-the-art dynamic vegetation model (LPJ-GUESS) in order to understand the long-term evolution of northern peatland ecosystems and to assess the effect of changing climate on peatland carbon balance. We combined a dynamic multi-layer approach (Frolking et al. 2010, Hilbert et al. 2000) with soil freezing-thawing functionality (Ekici et al. 2015, Wania et al. 2009a) in LPJ-GUESS. The new model is named LPJ-GUESS Peatland (LPJ-GUESS-P) (Chaudhary et al. in prep). The model was calibrated and tested at the sub-arctic mire in Stordalen, Sweden, and the model was able to capture the reported long-term vegetation dynamics and peat accumulation patterns in the mire (Kokfelt et al. 2010). For evaluation, the model was run at 13 grid points across a north to south transect in Europe. The modelled peat accumulation values were found to be consistent with the published data for each grid point (Loisel et al. 2014). Finally, a series of additional experiments were carried out to investigate the vulnerability of high-latitude peatlands to climate change. We find that the Stordalen mire will sequester more carbon in the future due to milder and wetter climate conditions, longer growing seasons, and the carbon fertilization effect. References: - Chaudhary et al. (in prep.). Modelling Holocene peatland and permafrost dynamics with the LPJ-GUESS dynamic vegetation model - Ekici A, et al. 2015. Site-level model intercomparison of high latitude and high altitude soil thermal dynamics in tundra and barren landscapes. The Cryosphere 9: 1343

  20. Drag coefficients for modeling flow through emergent vegetation in the Florida Everglades

    USGS Publications Warehouse

    Lee, J.K.; Roig, L.C.; Jenter, H.L.; Visser, H.M.

    2004-01-01

    Hydraulic data collected in a flume fitted with pans of sawgrass were analyzed to determine the vertically averaged drag coefficient as a function of vegetation characteristics. The drag coefficient is required for modeling flow through emergent vegetation at low Reynolds numbers in the Florida Everglades. Parameters of the vegetation, such as the stem population per unit bed area and the average stem/leaf width, were measured for five fixed vegetation layers. The vertically averaged vegetation parameters for each experiment were then computed by weighted average over the submerged portion of the vegetation. Only laminar flow through emergent vegetation was considered, because this is the dominant flow regime of the inland Everglades. A functional form for the vegetation drag coefficient was determined by linear regression of the logarithmic transforms of measured resistance force and Reynolds number. The coefficients of the drag coefficient function were then determined for the Everglades, using extensive flow and vegetation measurements taken in the field. The Everglades data show that the stem spacing and the Reynolds number are important parameters for the determination of vegetation drag coefficient. ?? 2004 Elsevier B.V. All rights reserved.

  1. Modeling the effect of wave-vegetation interaction on wave setup

    NASA Astrophysics Data System (ADS)

    van Rooijen, A. A.; McCall, R. T.; van Thiel de Vries, J. S. M.; van Dongeren, A. R.; Reniers, A. J. H. M.; Roelvink, J. A.

    2016-06-01

    Aquatic vegetation in the coastal zone attenuates wave energy and reduces the risk of coastal hazards, e.g., flooding. Besides the attenuation of sea-swell waves, vegetation may also affect infragravity-band (IG) waves and wave setup. To date, knowledge on the effect of vegetation on IG waves and wave setup is lacking, while they are potentially important parameters for coastal risk assessment. In this study, the storm impact model XBeach is extended with formulations for attenuation of sea-swell and IG waves, and wave setup effects in two modes: the sea-swell wave phase-resolving (nonhydrostatic) and the phase-averaged (surfbeat) mode. In surfbeat mode, a wave shape model is implemented to capture the effect of nonlinear wave-vegetation interaction processes on wave setup. Both modeling modes are verified using data from two flume experiments with mimic vegetation and show good skill in computing the sea-swell and IG wave transformation, and wave setup. In surfbeat mode, the wave setup prediction greatly improves when using the wave shape model, while in nonhydrostatic mode (nonlinear) intrawave effects are directly accounted for. Subsequently, the model is used for a range of coastal geomorphological configurations by varying bed slope and vegetation extent. The results indicate that the effect of wave-vegetation interaction on wave setup may be relevant for a range of typical coastal geomorphological configurations (e.g., relatively steep to gentle slope coasts fronted by vegetation).

  2. Assessing top- and subsoil organic carbon stocks of Low-Input High-Diversity systems using soil and vegetation characteristics.

    PubMed

    Ottoy, Sam; Van Meerbeek, Koenraad; Sindayihebura, Anicet; Hermy, Martin; Van Orshoven, Jos

    2017-03-01

    The soil organic carbon (SOC) stock is an important indicator in ecosystem service assessments. Even though a considerable fraction of the total stock is stored in the subsoil, current assessments often consider the topsoil only. Furthermore, mapping efforts are hampered by the limited spatial density of these topsoil measurements. The aim of this study was to assess the SOC stock in the upper 100cm of soil in 30,556ha of Low-Input High-Diversity systems, such as nature reserves, in Flanders (Belgium) and compare this estimate with the stock found in the topsoil (upper 15cm). To this end, we combined depth extrapolation of 139 measurements limited to the topsoil with four digital soil mapping techniques: multiple linear regression, boosted regression trees, artificial neural networks and least-squares support vector machines. Particular attention was given to vegetation characteristics as predictors. For both the stock in the upper 15cm and 100cm, a boosted regression trees approach was most informative as it resulted in the lowest cross-validation errors and provided insights in the relative importance of predictors. The predictors of the stock in the upper 100cm were soil type, groundwater level, clay fraction and community weighted mean (CWM) and variance (CWV) of plant height. These predictors, together with the CWM of specific leaf area, aboveground biomass production, CWV and CWM of rooting depth, terrain slope, CWM of mycorrhizal associations and species diversity also explained the topsoil stock. Our total stock estimates show that focusing on the topsoil (1.63Tg OC) only considers 36% of the stock in the upper 100cm (4.53Tg OC). Given the magnitude of subsoil OC and its dependency on typical ecosystem characteristics, it should not be neglected in regional ecosystem service assessments.

  3. Effects of vegetation feedback in modeling the present-day climate over China

    NASA Astrophysics Data System (ADS)

    Shi, Y.; Wang, G.; Erfanian, A.; Yu, M.

    2016-12-01

    Abstract: Proper representation of climate-vegetation interactions is important for realistic simulations of the present climate and reliable projections of the future, and dynamic vegetation is being incorporated into more and more climate models. However, coupled vegetation-climate modeling at the regional scale is still at a very early stage. Specifically, very few studies on climate over Asia have accounted for the role of dynamic vegetation feedback. In this study, the regional climate model RegCM version 4.3.4 (RCM) coupled with the Community Land Model version 4/4.5 (CLM) including models of carbon-nitrogen dynamics (CN) and vegetation dynamics (DV) is used to simulate the present day climate over China, and the role of vegetation feedback at different time scales is investigated based on a set of simulations with different treatments of vegetation. Three simulations are conducted, each using RCM-CLM, RCM-CLM-CN, and RCM-CLM-CN-DV respectively, and all simulations are driven with reanalysis data during the period of 1989 to 2009. This presentation will document the model performance in simulating vegetation and climate, and examine the role of vegetation dynamics in climate variability at different time scales. Preliminary results indicate that, when the carbon-nitrogen dynamics and dynamic vegetation feedback are included, the spatial pattern of biases remains similar, but the magnitude of the biases become larger. Model performance in simulating other aspects of the present-day climate will be examined, and the implication of this effect will be studied.

  4. 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.

  5. 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.

  6. 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

  7. A gradient model of vegetation and climate utilizing NOAA satellite imagery. Phase 1: Texas transect

    NASA Technical Reports Server (NTRS)

    Greegor, D. H.; Norwine, J.

    1981-01-01

    A new experimental climatological model/variable termed the sponge, a measure of moisture availability based on daily temperature maxima and minima and precipitation, is tested for potential biogeographic, ecological, and agro-climatological applications. Results, depicted in tabular and graphic from, suggest that, as a generalized climatic index, sponge's simplicity and sensitivity make particularly appropriate for trans-regional biogeographic studies (e.g., large-area and global vegetation monitoring). The feasibility of utilizing NOAA/AVHRR data for vegetation classification was investigated and a vegetation gradient model that utilizes sponge, and AVHRR pixel data (channels 1 and 2) were obtained for 12 locations. The normalized difference values for the AVHRR data when plotted against vegetation characteristics (biomass, net productivity, leaf area) and sponge values suggest that a multivariate gradient model incorporating AVHRR and sponge data may indeed be useful in global vegetation stratification and monitoring.

  8. A gradient model of vegetation and climate utilizing NOAA satellite imagery. Phase 1: Texas transect

    NASA Technical Reports Server (NTRS)

    Greegor, D. H.; Norwine, J.

    1981-01-01

    A new experimental climatological model/variable termed the sponge, a measure of moisture availability based on daily temperature maxima and minima and precipitation, is tested for potential biogeographic, ecological, and agro-climatological applications. Results, depicted in tabular and graphic from, suggest that, as a generalized climatic index, sponge's simplicity and sensitivity make particularly appropriate for trans-regional biogeographic studies (e.g., large-area and global vegetation monitoring). The feasibility of utilizing NOAA/AVHRR data for vegetation classification was investigated and a vegetation gradient model that utilizes sponge, and AVHRR pixel data (channels 1 and 2) were obtained for 12 locations. The normalized difference values for the AVHRR data when plotted against vegetation characteristics (biomass, net productivity, leaf area) and sponge values suggest that a multivariate gradient model incorporating AVHRR and sponge data may indeed be useful in global vegetation stratification and monitoring.

  9. Microwave measurement and modeling of the dielectric properties of vegetation

    NASA Astrophysics Data System (ADS)

    Shrestha, Bijay Lal

    Some of the important applications of microwaves in the industrial, scientific and medical sectors include processing and treatment of various materials, and determining their physical properties. The dielectric properties of the materials of interest are paramount irrespective of the applications, hence, a wide range of materials covering food products, building materials, ores and fuels, and biological materials have been investigated for their dielectric properties. However, very few studies have been conducted towards the measurement of dielectric properties of green vegetations, including commercially important plant crops such as alfalfa. Because of its high nutritional value, there is a huge demand for this plant and its processed products in national and international markets, and an investigation into the possibility of applying microwaves to improve both the net yield and quality of the crop can be beneficial. Therefore, a dielectric measurement system based upon the probe reflection technique has been set up to measure dielectric properties of green plants over a frequency range from 300 MHz to 18 GHz, moisture contents from 12%, wet basis to 79%, wet basis, and temperatures from -15°C to 30°C. Dielectric properties of chopped alfalfa were measured with this system over frequency range of 300 MHz to 18 GHz, moisture content from 11.5%, wet basis, to 73%, wet basis, and density over the range from 139 kg m-3 to 716 kg m-3 at 23°C. The system accuracy was found to be +/-6% and +/-10% in measuring the dielectric constant and loss factor respectively. Empirical, semi empirical and theoretical models that require only moisture content and operating frequency were determined to represent the dielectric properties of both leaves and stems of alfalfa at 22°C. The empirical models fitted the measured dielectric data extremely well. The root mean square error (RMSE) and the coefficient of determination (r2) for dielectric constant and loss factor of leaves

  10. Use of the forest vegetation simulator to quantify disturbance activities in state and transition models

    Treesearch

    Reuben Weisz; Don Vandendriesche

    2012-01-01

    The Forest Vegetation Simulator (FVS) has been used to provide rates of natural growth transitions under endemic conditions for use in State and Transition Models (STMs). This process has previously been presented. This paper expands on that work by citing the methods used to capture resultant vegetation states following disturbance activities; be it of natural causes...

  11. Item Response Modeling: An Evaluation of the Children's Fruit and Vegetable Self-Efficacy Questionnaire

    ERIC Educational Resources Information Center

    Watson, Kathy; Baranowski, Tom; Thompson, Debbe

    2006-01-01

    Perceived self-efficacy (SE) for eating fruit and vegetables (FV) is a key variable mediating FV change in interventions. This study applies item response modeling (IRM) to a fruit, juice and vegetable self-efficacy questionnaire (FVSEQ) previously validated with classical test theory (CTT) procedures. The 24-item (five-point Likert scale) FVSEQ…

  12. Item Response Modeling: An Evaluation of the Children's Fruit and Vegetable Self-Efficacy Questionnaire

    ERIC Educational Resources Information Center

    Watson, Kathy; Baranowski, Tom; Thompson, Debbe

    2006-01-01

    Perceived self-efficacy (SE) for eating fruit and vegetables (FV) is a key variable mediating FV change in interventions. This study applies item response modeling (IRM) to a fruit, juice and vegetable self-efficacy questionnaire (FVSEQ) previously validated with classical test theory (CTT) procedures. The 24-item (five-point Likert scale) FVSEQ…

  13. Perceptions of diverse educators regarding ethnic-minority deaf college students, role models, and diversity.

    PubMed

    Parasnis, Ila; Fischer, Susan D

    2005-01-01

    IN A QUALITATIVE STUDY, the researchers documented the perceptions of deaf and hearing ethnically diverse university faculty and staff regarding issues related to the education of ethnic-minority deaf college students. These experienced educators commented on the importance of ethnic-minority role models for deaf college students, the academic preparedness of ethnic-minority deaf students, these students' level of comfort on campus, and the success of institutional efforts to increase awareness regarding ethnic diversity. The insightful reflections of these diverse educators can be informative in improving the educational experience of ethnic-minority deaf students.

  14. 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

  15. Using the Adventure Model to Teach about Diversity and Tolerance

    ERIC Educational Resources Information Center

    Latess, Dennis R.; Walker, Richard L.

    2011-01-01

    There are a variety of curricular approaches in physical education, any one of which can provide a framework and scheme that is the foundation of a physical education unit of study. This article will discuss the use of an adventure model to teach about diversity, multi-cultural understanding and tolerance. Teaching children diversity and tolerance…

  16. The Diversity Challenge: A Collection of Model Programs.

    ERIC Educational Resources Information Center

    Mellander, Gustavo A., Ed.; Prochaska, Fred, Ed.

    Model programs designed to promote diversity within the West Valley-Mission Community College District (WVMCCD) in California are discussed and described in this report. First, an introductory chapter, "The Importance of Cultural Issues to Higher Education," by Gustavo A. Mellander and Fred Prochaska, reviews the diversity recommendations of the…

  17. Estimating fractional vegetation cover of oasis in Tarim Basin, China, using dimidiate fractional cover model

    NASA Astrophysics Data System (ADS)

    Han, Xiaoyong; Han, Ling

    2015-12-01

    Oasis is an important component of desert ecosystem. This paper employs Landsat Thematic Mapper (TM) multi-spectral data to extract fractional vegetation cover of oasis in Tarim Basin with four methods. The mixture pixel decomposition model based on normalized difference vegetation index(NDVI) is firstly used to estimate fractional vegetation cover(FVC). The results indicated that the method is mainly underestimating the FVC at the low FVC area and overestimating the FVC at high FVC area. Thereafter, a stepwise regression model between 15 Vegetation Indices (VIs) and measured FVC data and a log-linear model have been established through the relation analysis of FVC and NDVI. Trials of these two models showed that they are mainly overestimating the FVC. Finally, a dimidiate fractional cover model was proposed, which is composed of two linear functions. When the NDVI is less than 0.3, the linear function is formed by stress related vegetation index (STVI1) and normal differential water index (NDWI) (R2, 0.764) while the NDVI is greater than 0.3, the linear function is composed of NDVI and perpendicular vegetation index (PVI) (R2, 0.801). The validation of the dimidiate fractional cover model has been tested with the measured data. In the optimal case, the mean error is 0.002 and the RMSE is 0.051, demonstrating that the model can be used in estimating fractional vegetation cover of oasis in Tarim Basin.

  18. Three Dimensional Morphodynamic and Vegetation Modeling of Wax Lake Delta

    NASA Astrophysics Data System (ADS)

    Khadka, A. K.; Meselhe, E. A.; Sadid, K. M.

    2013-12-01

    The Wax Lake Delta (WLD) is located at the downstream end of the Wax Lake outlet, approximately 13 miles upstream from Morgan City, Louisiana. In 1942 the United States Army Corps of Engineer (USACE) dredged Wax Lake Outlet channel from lower Atchafalaya River to reduce flood stages at Morgan City. The channel diverts 50% of Atchafalaya River water and sediment to WLD. Since 1942, the WLD has been building seaward due to the deposition of sediment at the channel mouth. Growth of this delta supports the concept of land building via river diversions. A process based morphodynamic model (Delft3D) with the ability to predict evolution of river-dominated deltas is used in this study to further our understanding of land-building and delta growth processes. Initial model bathymetry is prepared based on USACE hydrographic survey of 1998 along with LIDAR survey data for over bank areas. Two continuous gauges at Wax Lake outlet near Calumet and Atchafalaya Bay near Eugene Island are used to assign upstream inflow and outflow boundary conditions, respectively. The model is calibrated and validated for Hydrodynamics and Sediment transport through two sets of field observations for flooded and average conditions. Vertical velocity and suspended sediment profiles made in the channels of the WLD in 2000 and 2001 are used for the model calibration and validation. More comprehensive field observations are being gathered as part of an ongoing study funded by the National Science Foundation (FESD-Delta Dynamics Collaboratory). Data include mutli-beam bathymetric data, velocities, sediment, and nutrient concentrations in the channels as well as on top of the islands. The Delft3D morphodynamic model for WLD provides quantitative information regarding water and sediment distribution among the inter-connected channel bifurcations, the exchange of sediment and nutrients between the channels and islands. The model is being used to investigate the rate of land building and delta growth from

  19. Accounting for spatial variation in vegetation properties improves simulations of Amazon forest biomass and productivity in a global vegetation model

    NASA Astrophysics Data System (ADS)

    de Almeida Castanho, A. D.; Coe, M. T.; Heil Costa, M.; Malhi, Y.; Galbraith, D.; Quesada, C. A.

    2012-08-01

    Dynamic vegetation models forced with spatially homogeneous biophysical parameters are capable of producing average productivity and biomass values for the Amazon basin forest biome that are close to the observed estimates, but are unable to reproduce the observed spatial variability. Recent observational studies have shown substantial regional spatial variability of above-ground productivity and biomass across the Amazon basin, which is believed to be primarily driven by soil physical and chemical properties. In this study, spatial heterogeneity of vegetation properties is added to the IBIS land surface model, and the simulated productivity and biomass of the Amazon basin are compared to observations from undisturbed forest. The maximum Rubisco carboxylation capacity (Vcmax) and the woody biomass residence time (τw) were found to be the most important properties determining the modeled spatial variation of above-ground woody net primary productivity and biomass, respectively. Spatial heterogeneity of these properties may lead to a spatial variability of 1.8 times in the simulated woody net primary productivity and 2.8 times in the woody above-ground biomass. The coefficient of correlation between the modeled and observed woody productivity improved from 0.10 with homogeneous parameters to 0.73 with spatially heterogeneous parameters, while the coefficient of correlation between the simulated and observed woody above-ground biomass improved from 0.33 to 0.88. The results from our analyses with the IBIS dynamic vegetation model demonstrate that using single values for key ecological parameters in the tropical forest biome severely limits simulation accuracy. We emphasize that our approach must be viewed as an important first step and that a clearer understanding of the biophysical mechanisms that drive the spatial variability of carbon allocation, τw and Vcmax are necessary.

  20. How much does weather-driven vegetation dynamics matter in land surface modelling?

    NASA Astrophysics Data System (ADS)

    Ingwersen, Joachim; Streck, Thilo

    2016-04-01

    Land surface models (LSM) are an essential part of weather and climate models as they provide the lower boundary condition for the atmospheric models. In state-of-the-art LSMs the seasonal vegetation dynamics is "frozen". The seasonal variation of vegetation state variables, such as leaf area index or green vegetation fraction, are prescribed in lookup tables. Hence, a year-by-year variation in the development of vegetation due to changing weather conditions cannot be considered. For climate simulations, this is obviously a severe drawback. The objective of the present study was to quantify the potential error in the simulation of land surface exchange processes resulting from "frozen" vegetation dynamics. For this purpose we simulated energy and water fluxes from a winter wheat stand and a maize stand in Southwest Germany. In a first set of simulations, six years (2010 to 2015) were simulated considering weather-driven vegetation dynamics. For this purpose, we coupled the generic crop growth model GECROS with the NOAH-MP model (NOAHMP-GECROS). In a second set of simulations all vegetation-related state variables of the 2010 simulation were written to an external file and were used to overwrite the vegetation-related state variables of the simulations of the years 2011-2015. The difference between both sets was taken as a measure for the potential error introduced to the LSM due to the assumption of a "frozen" vegetation dynamics. We will present first results and discuss the impact of "frozen" vegetation dynamics on climate change simulations.

  1. Significant inconsistency of vegetation carbon density in CMIP5 Earth system models against observational data

    DOE PAGES

    Yin, Yunhe; Song, Xia; Xu, Xiaofeng; ...

    2017-06-01

    Earth System Models (ESMs) have been widely used for projecting global vegetation carbon dynamics, yet how well ESMs performed for simulating vegetation carbon density remains untested. We compiled observational data of vegetation carbon density from literature and existing datasets to evaluate nine ESMs at site, biome, latitude and global scales. Three variables – root (including fine and coarse roots), total vegetation carbon density, and the root: total vegetation carbon ratios (R/T ratios), were chosen for ESM evaluation. ESM models performed well in simulating the spatial distribution of carbon densities in root (r = 0.71) and total vegetation (r = 0.62).more » However, ESM models had significant biases in simulating absolute carbon densities in root and total vegetation biomass across the majority of land ecosystems, especially in tropical and arctic ecosystems. Particularly, ESMs significantly overestimated carbon density in root (183%) and total vegetation biomass (167%) in climate zones of 10S ~ 10N. Substantial discrepancies between modeled and observed R/T ratios were found: the R/T ratios from ESMs were relatively constant, approximately 0.2 across all ecosystems, along latitudinal gradients, and in tropic, temperate, and arctic climatic zones, which was significantly different from the observed large variations in the R/T ratios (0.1 ~ 0.8). There were substantial inconsistencies between ESMs derived carbon density in root and total vegetation biomass and the R/T ratio at multiple scales, indicating urgent needs for model improvements on carbon allocation algorithms and more intensive field campaigns targeting carbon density in all key vegetation components.« less

  2. Soil C and N models that integrate microbial diversity.

    PubMed

    Louis, Benjamin P; Maron, Pierre-Alain; Viaud, Valérie; Leterme, Philippe; Menasseri-Aubry, Safya

    Industrial agriculture is yearly responsible for the loss of 55-100 Pg of historical soil carbon and 9.9 Tg of reactive nitrogen worldwide. Therefore, management practices should be adapted to preserve ecological processes and reduce inputs and environmental impacts. In particular, the management of soil organic matter (SOM) is a key factor influencing C and N cycles. Soil microorganisms play a central role in SOM dynamics. For instance, microbial diversity may explain up to 77 % of carbon mineralisation activities. However, soil microbial diversity is actually rarely taken into account in models of C and N dynamics. Here, we review the influence of microbial diversity on C and N dynamics, and the integration of microbial diversity in soil C and N models. We found that a gain of microbial richness and evenness enhances soil C and N dynamics on the average, though the improvement of C and N dynamics depends on the composition of microbial community. We reviewed 50 models integrating soil microbial diversity. More than 90 % of models integrate microbial diversity with discrete compartments representing conceptual functional groups (64 %) or identified taxonomic groups interacting in a food web (28 %). Half of the models have not been tested against an empirical dataset while the other half mainly consider fixed parameters. This is due to the difficulty to link taxonomic and functional diversity.

  3. Laboratory measurements of wave attenuation through model and live vegetation

    USDA-ARS?s Scientific Manuscript database

    Surge and waves generated by hurricanes and tropical storms often cause severe damage and loss of life in coastal areas. It is widely recognized that wetlands along coastal fringes reduce storm surge and waves. Yet, the potential role and primary mechanisms of wave mitigation by wetland vegetation a...

  4. Experimental investigation of wave attenuation through model and live vegetation

    USDA-ARS?s Scientific Manuscript database

    Hurricanes and tropical storms often cause severe damage and loss of life in coastal areas. It is widely recognized that wetlands along coastal fringes reduce storm surge and waves. Yet, the potential role and primary mechanisms of wave mitigation by wetland vegetation are not fully understood. K...

  5. Powdered hide model for vegetable tanning II. hydrolyzable tannin

    USDA-ARS?s Scientific Manuscript database

    Vegetable tannages employ both condensed and hydrolyzable tannins. As part of our exploration of tanning mechanisms, we reported last year on interactions of the condensed tannin, quebracho, with powdered hide. In this study, the interactions of chestnut extract, a hydrolyzable tannin, with powdere...

  6. Modeling the effects of urban vegetation on air pollution

    Treesearch

    David J. Nowak; Patrick J. McHale; Myriam Ibarra; Daniel Crane; Jack C. Stevens; Chris J. Luley

    1998-01-01

    Urban vegetation can directly and indirectly affect local and regional air quality by altering the urban atmospheric environment. Trees affect local air temperature by transpiring water through their leaves, by blocking solar radiation (tree shade), which reduces radiation absorption and heat storage by various anthropogenic surfaces (e.g., buildings, roads), and by...

  7. Chapter 9 - Vegetation succession modeling for the LANDFIRE Prototype Project

    Treesearch

    Donald Long; B. John (Jack) Losensky; Donald Bedunah

    2006-01-01

    One of the main objectives of the Landscape Fire and Resource Management Planning Tools Prototype Project, or LANDFIRE Prototype Project, was to determine departure of current vegetation conditions from the range and variation of conditions that existed during the historical era identified in the LANDFIRE guidelines as 1600-1900 A.D. (Keane and Rollins, Ch. 3). In...

  8. A model for predicting continental-scale vegetation distribution and water balance

    SciTech Connect

    Neilson, R.P.

    1995-05-01

    A Mapped atmosphere-Plant-Soil System (MAPSS) has been constructed for simulating the potential biosphere impacts and biosphere-atmosphere feedbacks from climatic change. The system calculates the potential vegetation type and leaf area that could be supported at a site, within the constraints of the abiotic climate. Both woody vegetation and grass are supported and compete for light and water. The woody vegetation can be either trees or shrubs, evergreen or deciduous, and needleleaved or broadleaved. A complete site water balance is calculated and integrates the vegetation leaf area and stomatal conductance in canopy transpiration and soil hydrology. The MAPSS model accurately simulates the distributions of forests, grasslands, and deserts and reproduces observed monthly runoff. The model can be used for predictions of new vegetation distribution patterns, soil moisture, and runoff patterns in alternative climates. 112 refs., 11 figs., 4 tabs.

  9. [Application of biotope mapping model integrated with vegetation cover continuity attributes in urban biodiversity conservation].

    PubMed

    Gao, Tian; Qiu, Ling; Chen, Cun-gen

    2010-09-01

    Based on the biotope classification system with vegetation structure as the framework, a modified biotope mapping model integrated with vegetation cover continuity attributes was developed, and applied to the study of the greenbelts in Helsingborg in southern Sweden. An evaluation of the vegetation cover continuity in the greenbelts was carried out by the comparisons of the vascular plant species richness in long- and short-continuity forests, based on the identification of woodland continuity by using ancient woodland indicator species (AWIS). In the test greenbelts, long-continuity woodlands had more AWIS. Among the forests where the dominant trees were more than 30-year-old, the long-continuity ones had a higher biodiversity of vascular plants, compared with the short-continuity ones with the similar vegetation structure. The modified biotope mapping model integrated with the continuity features of vegetation cover could be an important tool in investigating urban biodiversity, and provide corresponding strategies for future urban biodiversity conservation.

  10. Modelling Miocene vegetation in Europe: New results of the CARAIB model

    NASA Astrophysics Data System (ADS)

    Francois, L.; Favre, E.; Utescher, T.; Suc, J.-P.; Dubois-Laurent, J.-M.; Huang, K.; Cheddadi, R.

    2009-04-01

    The aim of this study is to present a new simulation of the vegetation with the CARAIB (CARbon Assimilation In the Biosphere) dynamic vegetation model for the Miocene in Europe. During this period, subtropical and tropical species were present in this area due to warmer climatic conditions. In order to better take in consideration these kinds of vegetations, we propose in this work a new classification of 26 groups. This adapted classification and the corresponding climatic tolerance parameters are based on the study of Dubois-Laurent et al. (J. Veg. Sci., 15, 739-746, 2004) for the tree types currently present in Europe, on the distributions of analogue species in south-eastern Asia and on some species distributions around the world. In the new classification 3 groups are devoted to herbs and 15 for trees including cold/cool/warm temperate, subtropical and tropical types. The 8 remaining groups are new ones and concern shrubs from arctic to tropical conditions. The new classification with the addition of shrubs will be used to improve the vegetation simulations with CARAIB for past, present an future periods.

  11. Do Stacked Species Distribution Models Reflect Altitudinal Diversity Patterns?

    PubMed Central

    Mateo, Rubén G.; Felicísimo, Ángel M.; Pottier, Julien; Guisan, Antoine; Muñoz, Jesús

    2012-01-01

    The objective of this study was to evaluate the performance of stacked species distribution models in predicting the alpha and gamma species diversity patterns of two important plant clades along elevation in the Andes. We modelled the distribution of the species in the Anthurium genus (53 species) and the Bromeliaceae family (89 species) using six modelling techniques. We combined all of the predictions for the same species in ensemble models based on two different criteria: the average of the rescaled predictions by all techniques and the average of the best techniques. The rescaled predictions were then reclassified into binary predictions (presence/absence). By stacking either the original predictions or binary predictions for both ensemble procedures, we obtained four different species richness models per taxa. The gamma and alpha diversity per elevation band (500 m) was also computed. To evaluate the prediction abilities for the four predictions of species richness and gamma diversity, the models were compared with the real data along an elevation gradient that was independently compiled by specialists. Finally, we also tested whether our richness models performed better than a null model of altitudinal changes of diversity based on the literature. Stacking of the ensemble prediction of the individual species models generated richness models that proved to be well correlated with the observed alpha diversity richness patterns along elevation and with the gamma diversity derived from the literature. Overall, these models tend to overpredict species richness. The use of the ensemble predictions from the species models built with different techniques seems very promising for modelling of species assemblages. Stacking of the binary models reduced the over-prediction, although more research is needed. The randomisation test proved to be a promising method for testing the performance of the stacked models, but other implementations may still be developed. PMID

  12. Do stacked species distribution models reflect altitudinal diversity patterns?

    PubMed

    Mateo, Rubén G; Felicísimo, Ángel M; Pottier, Julien; Guisan, Antoine; Muñoz, Jesús

    2012-01-01

    The objective of this study was to evaluate the performance of stacked species distribution models in predicting the alpha and gamma species diversity patterns of two important plant clades along elevation in the Andes. We modelled the distribution of the species in the Anthurium genus (53 species) and the Bromeliaceae family (89 species) using six modelling techniques. We combined all of the predictions for the same species in ensemble models based on two different criteria: the average of the rescaled predictions by all techniques and the average of the best techniques. The rescaled predictions were then reclassified into binary predictions (presence/absence). By stacking either the original predictions or binary predictions for both ensemble procedures, we obtained four different species richness models per taxa. The gamma and alpha diversity per elevation band (500 m) was also computed. To evaluate the prediction abilities for the four predictions of species richness and gamma diversity, the models were compared with the real data along an elevation gradient that was independently compiled by specialists. Finally, we also tested whether our richness models performed better than a null model of altitudinal changes of diversity based on the literature. Stacking of the ensemble prediction of the individual species models generated richness models that proved to be well correlated with the observed alpha diversity richness patterns along elevation and with the gamma diversity derived from the literature. Overall, these models tend to overpredict species richness. The use of the ensemble predictions from the species models built with different techniques seems very promising for modelling of species assemblages. Stacking of the binary models reduced the over-prediction, although more research is needed. The randomisation test proved to be a promising method for testing the performance of the stacked models, but other implementations may still be developed.

  13. Modelling of groundwater-vegetation interactions in a tidal marsh

    NASA Astrophysics Data System (ADS)

    Xin, Pei; Kong, Jun; Li, Ling; Barry, D. A.

    2013-07-01

    Wetting and drying due to tidal fluctuations affect soil conditions and hence plant growth in tidal marshes. Here, a coupled one-dimensional model was developed to simulate interacting groundwater flow and plant growth in these wetlands. The simulation results revealed three characteristic zones of soil conditions for plant growth along a cross-creek section subjected to the combined influences of spring-neap tides and evapotranspiration: (1) a near-creek zone affected by semi-diurnal tides over the whole spring-neap cycle, where the soil is well aerated although the plant growth could be slightly limited by the local water content dropping periodically below the wilting point on the ebb tide; (2) a less well-drained zone where drainage occurs only during neap tides (for which the daily inundation is absent) and plant growth is aeration-limited; and (3) an interior zone where evapotranspiration determines the soil-water saturation. Plant growth dynamics, which depend on these soil conditions, lead to spatial biomass distributions that are consistent with the characteristic zonation. The simulations shed light on the feedback mechanism for groundwater-vegetation interactions in the marsh system. It was demonstrated that the growth of pioneer plants can improve the soil aeration condition as a result of transpiration. The strength of this feedback varies spatially in accordance with the three characteristic zones of soil-water saturation. However, the development of another species in the marsh system is likely to be more complicated than suggested by the "positive feedback" mechanism proposed previously, due to the influence of inter-species competition. The feedback effects are generally more complex, involving both plant growth enhancement and inhibition depending on the combined influence of the intra- and inter-species competition, the ecosystem's carrying capacity and plant transpiration. These findings demonstrate the interplay of ecological and hydrological

  14. Modeling Mediterranean Riparian Vegetation Dynamics from Hydrologic Changes Conducted by Climate Change

    NASA Astrophysics Data System (ADS)

    Rivaes, R. P.; Rodríguez-González, P.; Albuquerque, A.; Ferriera, M.; Pinheiro, A.

    2010-12-01

    The present study is part of an IWRM ERA-NET (European Research Area-NET, Regional or National research programs network on Integrated Water Resource Management) project named "RIPFLOW - Riparian vegetation modeling for the assessment of environmental flow regimes and climate change impacts within the WFD”. The project aims to develop a flexible dynamic model of riparian habitats and vegetation to be easily applied in a wide range of conditions across Europe (from humid regions of Austria to Mediterranean conditions, including rivers with permanent and non-permanent flow regimes) with the application to some case studies in the countries involved (Portugal, Austria, Spain). The dynamic vegetation model developed will allow assessing the ecological integrity of river functioning, regarding the flow regime as the most relevant factor shaping these plant communities. The rules underlying the dynamic vegetation model used take into account the vegetation succession phases, topography and hydrologic regime. The water level of each flow and spring flow water table have particular influence on the spread and regeneration of species, while the shear stress and flood duration determines the maintenance or entrainment of existing vegetation. The model is considered dynamic because allows changing, in an annual scale, all the parameters used in the modeling process. This model uses as input for the following year the output of the previous one, thus considering the preceding dynamics exerted on the vegetation patches and also changes on the physical nature of the study site. After computation, the model output is a series of annual maps of the vegetation succession phase patches. This model brings the innovation of working at the response guild level, allowing regional calibration and application instead of being site use restricted. In Portugal, the model was applied in a Mediterranean river aiming to predict the spatio-temporal evolution of the riparian vegetation patches

  15. Developing an algorithm for enhancement of a digital terrain model for a densely vegetated floodplain wetland

    NASA Astrophysics Data System (ADS)

    Mirosław-Świątek, Dorota; Szporak-Wasilewska, Sylwia; Michałowski, Robert; Kardel, Ignacy; Grygoruk, Mateusz

    2016-07-01

    Airborne laser scanning survey data were conducted with a scanning density of 4 points/m2 to accurately map the surface of a unique central European complex of wetlands: the lower Biebrza River valley (Poland). A method to correct a degrading effect of vegetation (so-called "vegetation effect") on digital terrain models (DTMs) was applied utilizing remotely sensed images, real-time kinematic global positioning system elevation measurements, topographical surveys, and vegetation height measurements. Geographic object-based image analysis (GEOBIA) was performed to map vegetation within the study area that was used as categories from which vegetation height information was derived for the DTM correction. The final DTM was compared with a model obtained, where additional correction of the "vegetation effect" was neglected. A comparison between corrected and uncorrected DTMs demonstrated the importance of accurate topography through a simple presentation of the discrepancies arising in features of the flood using various DTM products. An overall map classification accuracy of 80% was attained with the use of GEOBIA. Correction factors developed for various types of the vegetation reached values from 0.08 up to 0.92 m and were dependent on the vegetation type.

  16. Effects of vegetation structure on biomass accumulation in a coupled water-carbon-energy balance model in West Africa

    NASA Astrophysics Data System (ADS)

    Yin, Zun; Dekker, Stefan; van den Hurk, Bart; Dijkstra, Henk

    2013-04-01

    A myriad of interactions exist between vegetation and local climate for arid and semi-arid regions. Vegetation function, structure and individual behavior have enormous impacts on carbon-water-energy balances, which consequently influence local climate variability that, in turn, feeds back to the vegetation. In this study, a conceptual vegetation structure scheme is formulated and tested in a new carbon-water-energy coupled model to explore the importance of vegetation structure on equilibrium biomass states. Two different strategies of vegetation adaptation to water stress are included. Surface energy, water and carbon fluxes are simulated for a range of vegetation structures across a precipitation gradient in West Africa and optimal vegetation structures that maximize biomass for each precipitation regime are determined. Under dry conditions vegetation tries to maximize the Water Use Efficiency and Leaf Area Index as it tries to maximize carbon gain. However, as the vegetation can also engineer its environment by extracting water from the surrounding bare soil (thereby forming patches of vertical vegetation) it can also minimize its vegetation cover. With increasing precipitation, the vegetation tries to maximize its cover as it then can reduce water loss from bare soil while having maximum carbon gain due to a large Leaf Area Index. The competition between vegetation and bare soil determines a transition between a 'survival' regime to a 'growing' regime. The new modeling framework is useful to represent the effects of dynamic vegetation structure in coupled land-atmosphere feedback models.

  17. The effects of vegetation and climate change on catchment erosion over millennial time scales: Insights from coupled dynamic vegetation and landscape evolution models

    NASA Astrophysics Data System (ADS)

    Schmid, Manuel; Ehlers, Todd; Werner, Christian; Hickler, Thomas

    2017-04-01

    Recent studies hypothesize that vegetation and the morphology of landscapes are strongly coupled. On a small scale, plants influence the erosivity of soil and sediments and therefore systematically impact catchment erosion and topography. Previous landscape evolution modeling studies primarily focus on changes in fluvial and hillslope erosion due to variations in climate and tectonics, without explicit consideration of vegetation effects. In this study, we complement previous work by investigating the effects of vegetation and vegetation change on hillslope and fluvial processes by combining LPJ-GUESS, a dynamic global vegetation model, with a modified version of the Landlab surface process model. The LandLab model was extended to account for vegetation-dependent sediment fluxes for both hillslope and detachment-limited fluvial erosion. The models are coupled by using predicted changes in surface vegetation from LPJ-GUESS for different climate scenarios as input for vegetation dependent erosional coefficients in Landlab. Simulations were conducted with the general climate and vegetation conditions representative between 25° and 40°S along the Coastal Cordillera of Chile. This region is the focus of the EarthShape research program (www.earthshape.net). These areas present a natural climatic and associated vegetation gradient that ranges from hyper-arid (Atacama desert) to humid-temperate conditions without a dry season and pristine temperate Araucaria forest. All study areas considered have a similar and uniform granite substrate, which minimizes lithologic variations and their effect on catchment erosion. Simulations are in progress that were designed to independently determine the climatic or vegetation controls on topography and erosion histories over the last 21 kyr. Our preliminary findings suggest that an increase in the surface vegetation results in a modulation of the mean hillslope angle and the average drainage density. In addition, we find that a

  18. Model investigation of the effect of vegetation on passive microwave soil moisture retrieval

    NASA Astrophysics Data System (ADS)

    Zhang, Zhongjun; Sun, Guoqing

    2003-04-01

    Many studies on soil moisture retrieval at vegetated area from microwave radiometry data assume a simple model of vegetation, which is characterized by vegetation volume fraction, effective dielectric constant, plant moisture content, etc. In this study, a radiative transfer model is used to model the emissivity and transmissivity of forest canopy, which is more realistically characterized as a volumetric medium consisting of discrete scatters (leaves, stems, tree branches, and trunks). To facilitate the soil moisture inversion from radiometry data, the unknown variables need to be reduced. The possibility of fitting the modeled emissivity and transmissivity of vegetation canopy into simple equations, and the relationships of these parameters between different microwave radiometry frequencies were studied and the results are presented in this paper.

  19. Dynamic modeling of vegetation change in arid lands

    NASA Technical Reports Server (NTRS)

    Robinson, V. B.; Coiner, J. C.; Barringer, T. H.

    1982-01-01

    A general framework for a digital desertification monitoring system (DDMS) for assessing the worldwide desertification growth rate is presented. The system relies on the development of Landsat derived indicators to identify local processes signalling the growth of arid regions. A study area consisting of the eastern edge of the Niger River delta in Mali was used to characterize three indicators in terms of the covariance of the multispectral scanner (MSS) bands 2 and 4, the correlation of the two bands, and the percent variance expressed by the first eigenvalue. The scenes are imaged multitemporallly in a 400 x 400 pixel array to detect vegetation cover changes. Criteria were defined which characterized the decrease or increase of vegetation. It was determined that the correlation coefficients are the best indicators, and are easily computed.

  20. Dynamic modeling of vegetation change in arid lands

    NASA Technical Reports Server (NTRS)

    Robinson, V. B.; Coiner, J. C.; Barringer, T. H.

    1982-01-01

    A general framework for a digital desertification monitoring system (DDMS) for assessing the worldwide desertification growth rate is presented. The system relies on the development of Landsat derived indicators to identify local processes signalling the growth of arid regions. A study area consisting of the eastern edge of the Niger River delta in Mali was used to characterize three indicators in terms of the covariance of the multispectral scanner (MSS) bands 2 and 4, the correlation of the two bands, and the percent variance expressed by the first eigenvalue. The scenes are imaged multitemporallly in a 400 x 400 pixel array to detect vegetation cover changes. Criteria were defined which characterized the decrease or increase of vegetation. It was determined that the correlation coefficients are the best indicators, and are easily computed.

  1. Vegetation Cover in a Warmer World Simulated using a Dynamic Global Vegetation Model for the mid Pliocene

    NASA Astrophysics Data System (ADS)

    Haywood, A. M.; Valdes, P. J.; Sellwood, B. W.

    2005-12-01

    In this study we employ the TRIFFID Dynamic Global Vegetation Model (DGVM) and the HadAM3 GCM to investigate vegetation distributions and climate-vegetation feedbacks during the mid Pliocene, and examine the implications of these results for the origins of hominid bipedalism. The TRIFFID model outputs broadly support extant palaeoenvironmental reconstructions for the mid Pliocene provided by the PRISM Group (Pliocene Research Interpretations and Synoptic Mapping). TRIFFID simulates a significant increase in forest cover, composed of Needle leaf trees in the higher latitudes of the Northern Hemisphere and Broad leaf trees in other regions. Needle leaf trees extend from the Arctic Coast into the northern mid latitudes. The fractional coverage of bare soil declines in North Africa, the Arabian Peninsula, Australia and southern South America which is consistent with PRISM's assertion of a reduced geographical coverage of arid deserts. A significant increase in the fractional coverage of both Broad leaf trees in Africa and South America is not indicative of a major expansion in the tropical rainforests. Rather, it represents an expansion of general forest and woodland type habitats in these regions. The principal impact of using a DGVM on the GCM predicted climatology is to reduce minimum and maximum temperature extremes, thus reducing the seasonality of temperature over wide regions. The expansion in Broad leaf trees in Africa is not compatible with the `savannah hypothesis' for the evolution of hominid bipedalism. Rather the results lend credence to an alternative hypothesis which suggests that bipedalism evolved in wooded to forested ecosystems and was, for several million years, linked to arborealism.

  2. Dealing with Diversity in Computational Cancer Modeling

    PubMed Central

    Johnson, David; McKeever, Steve; Stamatakos, Georgios; Dionysiou, Dimitra; Graf, Norbert; Sakkalis, Vangelis; Marias, Konstantinos; Wang, Zhihui; Deisboeck, Thomas S.

    2013-01-01

    This paper discusses the need for interconnecting computational cancer models from different sources and scales within clinically relevant scenarios to increase the accuracy of the models and speed up their clinical adaptation, validation, and eventual translation. We briefly review current interoperability efforts drawing upon our experiences with the development of in silico models for predictive oncology within a number of European Commission Virtual Physiological Human initiative projects on cancer. A clinically relevant scenario, addressing brain tumor modeling that illustrates the need for coupling models from different sources and levels of complexity, is described. General approaches to enabling interoperability using XML-based markup languages for biological modeling are reviewed, concluding with a discussion on efforts towards developing cancer-specific XML markup to couple multiple component models for predictive in silico oncology. PMID:23700360

  3. Evaluation of a new model of aeolian transport in the presence of vegetation

    USGS Publications Warehouse

    Li, Junran; Okin, Gregory S.; Herrick, Jeffrey E.; Belnap, Jayne; Miller, Mark E.; Vest, Kimberly; Draut, Amy E.

    2013-01-01

    Aeolian transport is an important characteristic of many arid and semiarid regions worldwide that affects dust emission and ecosystem processes. The purpose of this paper is to evaluate a recent model of aeolian transport in the presence of vegetation. This approach differs from previous models by accounting for how vegetation affects the distribution of shear velocity on the surface rather than merely calculating the average effect of vegetation on surface shear velocity or simply using empirical relationships. Vegetation, soil, and meteorological data at 65 field sites with measurements of horizontal aeolian flux were collected from the Western United States. Measured fluxes were tested against modeled values to evaluate model performance, to obtain a set of optimum model parameters, and to estimate the uncertainty in these parameters. The same field data were used to model horizontal aeolian flux using three other schemes. Our results show that the model can predict horizontal aeolian flux with an approximate relative error of 2.1 and that further empirical corrections can reduce the approximate relative error to 1.0. The level of error is within what would be expected given uncertainties in threshold shear velocity and wind speed at our sites. The model outperforms the alternative schemes both in terms of approximate relative error and the number of sites at which threshold shear velocity was exceeded. These results lend support to an understanding of the physics of aeolian transport in which (1) vegetation's impact on transport is dependent upon the distribution of vegetation rather than merely its average lateral cover and (2) vegetation impacts surface shear stress locally by depressing it in the immediate lee of plants rather than by changing the bulk surface's threshold shear velocity. Our results also suggest that threshold shear velocity is exceeded more than might be estimated by single measurements of threshold shear stress and roughness length

  4. Modelling the effect of vegetation on the formation of boundary layer cumulus during FIFE

    NASA Technical Reports Server (NTRS)

    Wetzel, Peter J.

    1990-01-01

    A 1D model is discussed which permits prediction of the effect of vegetation cover on the area-averaged boundary layer. Special attention is given to the manner in which the relative contributions of sensible and latent heat fluxes to the surface-energy budget are determined by the vegetation. The model can be effectively applied to the heterogeneous prairie environment to predict cloud cover at different times of the year demonstrating good agreement with observed conditions.

  5. Modelling Holocene peatland dynamics with an individual-based dynamic vegetation model

    NASA Astrophysics Data System (ADS)

    Chaudhary, Nitin; Miller, Paul A.; Smith, Benjamin

    2017-05-01

    Dynamic global vegetation models (DGVMs) are designed for the study of past, present and future vegetation patterns together with associated biogeochemical cycles and climate feedbacks. However, most DGVMs do not yet have detailed representations of permafrost and non-permafrost peatlands, which are an important store of carbon, particularly at high latitudes. We demonstrate a new implementation of peatland dynamics in a customized Arctic version of the LPJ-GUESS DGVM, simulating the long-term evolution of selected northern peatland ecosystems and assessing the effect of changing climate on peatland carbon balance. Our approach employs a dynamic multi-layer soil with representation of freeze-thaw processes and litter inputs from a dynamically varying mixture of the main peatland plant functional types: mosses, shrubs and graminoids. The model was calibrated and tested for a sub-Arctic mire in Stordalen, Sweden, and validated at a temperate bog site in Mer Bleue, Canada. A regional evaluation of simulated carbon fluxes, hydrology and vegetation dynamics encompassed additional locations spread across Scandinavia. Simulated peat accumulation was found to be generally consistent with published data and the model was able to capture reported long-term vegetation dynamics, water table position and carbon fluxes. A series of sensitivity experiments were carried out to investigate the vulnerability of high-latitude peatlands to climate change. We found that the Stordalen mire may be expected to sequester more carbon in the first half of the 21st century due to milder and wetter climate conditions, a longer growing season, and the CO2 fertilization effect, turning into a carbon source after mid-century because of higher decomposition rates in response to warming soils.

  6. An Analytical Model for the Distributions of Velocity and Discharge in Compound Channels with Submerged Vegetation

    PubMed Central

    Jiang, Beihan; Yang, Kejun; Cao, Shuyou

    2015-01-01

    Based on the momentum transfer theory, an analytical model is proposed for the velocity and discharge distributions in compound channels with submerged vegetation on the floodplain. The partially vegetated channel was divided into three sub-regions, i.e. the main channel region, the floodplain region with submerged vegetation and the floodplain region without vegetation. For each region, the force balance relationship was established, and the momentum transfer between different regions was presented. Verification by the experimental data and comparison with the traditional method shows that the proposed method is capable of predicting for the velocity and discharge distributions in compound channels with submerged vegetation and is superior to the conventional method. The results also show that when the momentum transfer between different regions is ignored, the computed discharge will be much lager than the measured data, and the error increases with the discharge, especially in the floodplain region. PMID:26161661

  7. Modelling the interactions between vegetation and climate from the Cretaceous to the Eocene

    NASA Astrophysics Data System (ADS)

    Loptson, Claire; Lunt, Dan; Francis, Jane

    2013-04-01

    The climates during the Cretaceous (~144 to 66 Ma) and the early Eocene (~56 to 48 Ma) were much warmer than the present day. Atmospheric CO2 levels for these past climates have a large uncertainty associated with them, but were possibly as high as 2000 to 3000 ppm for the early Eocene (Beerling and Royer, 2011; Lowenstein and Demicco, 2006) and maximum values are thought to range from 800 to 1800 ppm during the Cretaceous (Royer et al., 2012). Current modelling efforts have had great difficulty in replicating the shallow latitudinal temperature gradient indicated by proxy data for these time periods (e.g. Heinemann et al., 2009; Winguth et al., 2010; Shellito et al., 2009). Mechanisms that can result in such a low temperature gradient have not been found (Winguth et al., 2010; Beerling et al., 2011; Sloan and Morrill, 1998), but a contributing factor could be that not all climate feedbacks are included in these models. Vegetation feedbacks have been shown to be especially important (e.g. Otto-Bliesner and Upchurch, 1997; Bonan, 2008) so by including a more accurate representation of vegetation in the climate model, the model-data discrepancies may be reduced. A fully coupled atmosphere-ocean GCM, HadCM3L, coupled to a dynamic global vegetation model (TRIFFID), was used to simulate the climate and the predicted vegetation distributions for and the early Eocene and 12 different time slices representing different ages throughout the Cretaceous at 4x pre-industrial CO2. The only difference in the way these simulations were set up are different boundary conditions that are specific to that time period, e.g. different solar constants and paleogeographies. This allows a direct comparison between the time slices. We present the changes in climate, and therefore vegetation, during the Cretaceous due to changes in these boundary conditions alone, with a focus on Antarctica. Additional Eocene simulations were also carried out with a) fixed globally-uniform vegetation and b

  8. The diversity changes of soil microbial communities stimulated by climate, soil type and vegetation type analyzed via a functional gene array.

    PubMed

    Chen, Fu; Tan, Min; Yang, Yongjun; Ma, Jing; Zhang, Shaoliang; Li, Gang

    2015-11-01

    The aim of this study was to analyze the changes of soil microbial communities stimulated by climate, soil type and vegetation type using a functional gene array. The dataset GSE51592 was obtained from Gene Expression Omnibus, including 54 soil samples. Genetic diversity variation of samples under different sites, soil and vegetation types was examined by calculating the percentage of specific gene number in each sample. Furthermore, gene functional categories and microorganism species in samples under different environmental factors were respectively divided. Gene number in samples with cropping was higher than in samples without cropping. When site, soil type and vegetation type were as the sole variable, respectively, the percentage of specific genes in samples from Yingtan, in phaeozem samples and in samples with cropping was higher. Furthermore, the percentage of gene number in organic remediation for phaeozem and cambisol samples was significant at p < 0.05, comparing with that for acrisol samples. At superkingdom level of microorganisms, for the same category, there was no significant difference (p < 0.05) between the samples. At phylum level, for the categories of Bacteroidetes and Cyanobacteria, the percentage of gene number in cambisol samples was significantly higher (p < 0.05). Conversely, in the category of Proteobacteria, the percentage of gene number in phaeozem and acrisol samples was markedly higher (p < 0.05). Microbial diversity of soil was cooperatively driven by climate, soil type and vegetation type.

  9. Parsimonious modeling of vegetation dynamics for ecohydrologic studies of water-limited ecosystems

    NASA Astrophysics Data System (ADS)

    Montaldo, Nicola; Rondena, Roberta; Albertson, John D.; Mancini, Marco

    2005-10-01

    The structure and function of vegetation regulate fluxes across the biosphere-atmosphere interface with large effects in water-limited ecosystems. Vegetation dynamics are often neglected in hydrological modeling except for simple prescriptions of seasonal phenology. However, changes in vegetation densities, influencing the partitioning of incoming solar energy into sensible and latent heat fluxes, can result in long-term changes in both local and global climates with resulting feedbacks on vegetation growth. This paper seeks a simple vegetation dynamics model (VDM) for simulation of the leaf area index (LAI) dynamics in hydrologic models. Five variants of a VDM are employed, with a range of model complexities. The VDMs are coupled to a land surface model (LSM), with the VDM providing the LAI evolution through time and the LSM using this to compute the land surface fluxes and update the soil water contents. We explore the models through case studies of water-limited grass fields in California (United States) and North Carolina (United States). Results show that a simple VDM, simulating only the living aboveground green biomass (i.e., with low parameterization), is able to accurately simulate the LAI. Results also highlight the importance of including the VDM in the LSM when studying the climate-soil-vegetation interactions over moderate to long timescales. The inclusion of the VDM in the LSM is demonstrated to be essential for assessing the impact of interannual rainfall variability on the water budget of a water limited region.

  10. Fractional Vegetation Cover Estimation Based on an Improved Selective Endmember Spectral Mixture Model

    PubMed Central

    Li, Ying; Wang, Hong; Li, Xiao Bing

    2015-01-01

    Vegetation is an important part of ecosystem and estimation of fractional vegetation cover is of significant meaning to monitoring of vegetation growth in a certain region. With Landsat TM images and HJ-1B images as data source, an improved selective endmember linear spectral mixture model (SELSMM) was put forward in this research to estimate the fractional vegetation cover in Huangfuchuan watershed in China. We compared the result with the vegetation coverage estimated with linear spectral mixture model (LSMM) and conducted accuracy test on the two results with field survey data to study the effectiveness of different models in estimation of vegetation coverage. Results indicated that: (1) the RMSE of the estimation result of SELSMM based on TM images is the lowest, which is 0.044. The RMSEs of the estimation results of LSMM based on TM images, SELSMM based on HJ-1B images and LSMM based on HJ-1B images are respectively 0.052, 0.077 and 0.082, which are all higher than that of SELSMM based on TM images; (2) the R2 of SELSMM based on TM images, LSMM based on TM images, SELSMM based on HJ-1B images and LSMM based on HJ-1B images are respectively 0.668, 0.531, 0.342 and 0.336. Among these models, SELSMM based on TM images has the highest estimation accuracy and also the highest correlation with measured vegetation coverage. Of the two methods tested, SELSMM is superior to LSMM in estimation of vegetation coverage and it is also better at unmixing mixed pixels of TM images than pixels of HJ-1B images. So, the SELSMM based on TM images is comparatively accurate and reliable in the research of regional fractional vegetation cover estimation. PMID:25905772

  11. Fractional vegetation cover estimation based on an improved selective endmember spectral mixture model.

    PubMed

    Li, Ying; Wang, Hong; Li, Xiao Bing

    2015-01-01

    Vegetation is an important part of ecosystem and estimation of fractional vegetation cover is of significant meaning to monitoring of vegetation growth in a certain region. With Landsat TM images and HJ-1B images as data source, an improved selective endmember linear spectral mixture model (SELSMM) was put forward in this research to estimate the fractional vegetation cover in Huangfuchuan watershed in China. We compared the result with the vegetation coverage estimated with linear spectral mixture model (LSMM) and conducted accuracy test on the two results with field survey data to study the effectiveness of different models in estimation of vegetation coverage. Results indicated that: (1) the RMSE of the estimation result of SELSMM based on TM images is the lowest, which is 0.044. The RMSEs of the estimation results of LSMM based on TM images, SELSMM based on HJ-1B images and LSMM based on HJ-1B images are respectively 0.052, 0.077 and 0.082, which are all higher than that of SELSMM based on TM images; (2) the R2 of SELSMM based on TM images, LSMM based on TM images, SELSMM based on HJ-1B images and LSMM based on HJ-1B images are respectively 0.668, 0.531, 0.342 and 0.336. Among these models, SELSMM based on TM images has the highest estimation accuracy and also the highest correlation with measured vegetation coverage. Of the two methods tested, SELSMM is superior to LSMM in estimation of vegetation coverage and it is also better at unmixing mixed pixels of TM images than pixels of HJ-1B images. So, the SELSMM based on TM images is comparatively accurate and reliable in the research of regional fractional vegetation cover estimation.

  12. Dietary Diversity and Vegetable and Fruit Consumption of Households in a Resource-Poor Peri-Urban South Africa Community Differ by Food Security Status.

    PubMed

    Faber, Mieke; Wenhold, Friede A M; Laurie, Sunette M

    2017-01-01

    Sociodemographic, living standard measure, consumption of vegetables and fruit, and dietary diversity in relation to household food security were assessed. Using a hunger score, households were categorized as food secure (n = 125) or food insecure (n = 273). Food secure respondents had a higher mean dietary diversity score (3.98; 95%CI [3.79, 4.18] versus 3.65; 95% [CI 3.53, 3.77]), were more likely to eat vitamin A-rich foods (OR 1.15; 95% CI [1.05, 1.26]), a more varied diet (DDS ≥ 4, OR 1.90; 95% CI [1.19, 3.13]), and vegetables daily (OR 3.37; 95% CI [2.00, 5.76]). Cost limited daily vegetable/fruit consumption in food insecure households. Respondents with ≥ 8 years of schooling were more likely (OR 2.07; 95% CI [1.22, 3.53]) and households receiving social grants were less likely (OR 0.37; 95% CI [0.19, 0.72]) to be food secure. Results highlight the association between dietary diversity and household food security.

  13. The Association between Self-Reported Grocery Store Access, Fruit and Vegetable Intake, Sugar-Sweetened Beverage Consumption, and Obesity in a Racially Diverse, Low-Income Population

    PubMed Central

    Gase, Lauren Nichol; DeFosset, Amelia Rose; Smith, Lisa V.; Kuo, Tony

    2014-01-01

    This study sought to examine the relationship between self-reported time and distance to the nearest retail grocery store, healthy and unhealthy food consumption, and objectively measured body mass index (BMI). We conducted a survey with 1,503 racially diverse, low-income residents at five public health centers in Los Angeles County. Most participants reported shopping at a supermarket (86.7%) and driving (59.9%) to their usual source for groceries. Over half reported living less than a mile from (58.9%) and traveling 5 min or less to reach (50.3%) the nearest grocery store. In the multivariable regression models, neither self-reported distance nor time to the nearest grocery store was consistently associated with fruit and vegetable intake, sugar-sweetened beverage consumption, or BMI. Results suggest that the need to consider access and quality as well as urban planning and transportation, when examining the relationship between the retail food environment and health outcomes. PMID:25426485

  14. Biglan Model Test Based on Institutional Diversity.

    ERIC Educational Resources Information Center

    Roskens, Ronald W.; Creswell, John W.

    The Biglan model, a theoretical framework for empirically examining the differences among subject areas, classifies according to three dimensions: adherence to common set of paradigms (hard or soft), application orientation (pure or applied), and emphasis on living systems (life or nonlife). Tests of the model are reviewed, and a further test is…

  15. DIVERSE MODELS FOR SOLVING CONTRASTING OUTFALL PROBLEMS

    EPA Science Inventory

    Mixing zone initial dilution and far-field models are useful for assuring that water quality criteria will be met when specific outfall discharge criteria are applied. Presented here is a selective review of mixing zone initial dilution models and relatively simple far-field tran...

  16. A structured model for vegetative growth and sporulation in Bacillus thuringiensis

    SciTech Connect

    Starzak, M.; Bajpai, R.K.

    1991-12-31

    A mathematical model has been developed for the 6-endotoxin producing Bacillus thuringiensis. The structure of the model involves the processes taking place during vegetative growth, those leading to the initiation of sporulation under conditions of carbon and/or nitrogen limitation, and the sporulation events. The key features in the model are the pools of compounds, such as PRPP, IMP, ADP/ATP, GDP/GTP, pyrimidine nucleotides, NAD/NADH{sub 2}, amino acids, nucleic acids, cell wall, and vegetative and sporulation proteins. These, along with a-factors that control the nature of RNA-polymerase during the different phases, effectively stimulate the vegetative growth and sporulation. The initiation of sporulation is controlled by the intracellular concentration of GTP. Results of simulation of vegetative growth, initiation of sporulation, spore protein formation, and production of {delta}-endotoxin under C- or N-limitation are presented.

  17. Forecasting alpine vegetation change using repeat sampling and a novel modeling approach.

    PubMed

    Johnson, David R; Ebert-May, Diane; Webber, Patrick J; Tweedie, Craig E

    2011-09-01

    Global change affects alpine ecosystems by, among many effects, by altering plant distributions and community composition. However, forecasting alpine vegetation change is challenged by a scarcity of studies observing change in fixed plots spanning decadal-time scales. We present in this article a probabilistic modeling approach that forecasts vegetation change on Niwot Ridge, CO using plant abundance data collected from marked plots established in 1971 and resampled in 1991 and 2001. Assuming future change can be inferred from past change, we extrapolate change for 100 years from 1971 and correlate trends for each plant community with time series environmental data (1971-2001). Models predict a decreased extent of Snowbed vegetation and an increased extent of Shrub Tundra by 2071. Mean annual maximum temperature and nitrogen deposition were the primary a posteriori correlates of plant community change. This modeling effort is useful for generating hypotheses of future vegetation change that can be tested with future sampling efforts.

  18. A structured model for vegetative growth and sporulation in Bacillus thuringiensis.

    PubMed

    Starzak, M; Bajpai, R K

    1991-01-01

    A mathematical model has been developed for the delta-endotoxin producing Bacillus thuringiensis. The structure of the model involves the processes taking place during vegetative growth, those leading to the initiation of sporulation under conditions of carbon and/or nitrogen limitation, and the sporulation events. The key features in the model are the pools of compounds, such as PRPP, IMP, ADP/ATP, GDP/GTP, pyrimidine nucleotides, NAD/NADH2, amino acids, nucleic acids, cell wall, and vegetative and sporulation proteins. These, along with sigma-factors that control the nature of RNA-polymerase during the different phases, effectively stimulate the vegetative growth and sporulation. The initiation of sporulation is controlled by the intracellular concentration of GTP. Results of simulation of vegetative growth, initiation of sporulation, spore protein formation, and production of delta-endotoxin under C- or N-limitation are presented.

  19. Integrating microbial diversity in soil carbon dynamic models parameters

    NASA Astrophysics Data System (ADS)

    Louis, Benjamin; Menasseri-Aubry, Safya; Leterme, Philippe; Maron, Pierre-Alain; Viaud, Valérie

    2015-04-01

    Faced with the numerous concerns about soil carbon dynamic, a large quantity of carbon dynamic models has been developed during the last century. These models are mainly in the form of deterministic compartment models with carbon fluxes between compartments represented by ordinary differential equations. Nowadays, lots of them consider the microbial biomass as a compartment of the soil organic matter (carbon quantity). But the amount of microbial carbon is rarely used in the differential equations of the models as a limiting factor. Additionally, microbial diversity and community composition are mostly missing, although last advances in soil microbial analytical methods during the two past decades have shown that these characteristics play also a significant role in soil carbon dynamic. As soil microorganisms are essential drivers of soil carbon dynamic, the question about explicitly integrating their role have become a key issue in soil carbon dynamic models development. Some interesting attempts can be found and are dominated by the incorporation of several compartments of different groups of microbial biomass in terms of functional traits and/or biogeochemical compositions to integrate microbial diversity. However, these models are basically heuristic models in the sense that they are used to test hypotheses through simulations. They have rarely been confronted to real data and thus cannot be used to predict realistic situations. The objective of this work was to empirically integrate microbial diversity in a simple model of carbon dynamic through statistical modelling of the model parameters. This work is based on available experimental results coming from a French National Research Agency program called DIMIMOS. Briefly, 13C-labelled wheat residue has been incorporated into soils with different pedological characteristics and land use history. Then, the soils have been incubated during 104 days and labelled and non-labelled CO2 fluxes have been measured at ten

  20. Predicting use of ineffective responsive, structure and control vegetable parenting practices with the Model of Goal Directed Behavior

    USDA-ARS?s Scientific Manuscript database

    This study reports the modeling of three categories of ineffective vegetable parenting practices (IVPP) separately (responsive, structure, and control vegetable parenting practices). An internet survey was employed for a cross sectional assessment of parenting practices and cognitive-emotional varia...

  1. Application of a coupled vegetation competition and groundwater simulation model to study effects of sea level rise and storm surges on coastal vegetation

    USGS Publications Warehouse

    Teh, Su Yean; Turtora, Michael; DeAngelis, Don; Jiang Jiang,; Pearlstine, Leonard G.; Smith, Thomas; Koh, Hock Lye

    2015-01-01

    Global climate change poses challenges to areas such as low-lying coastal zones, where sea level rise (SLR) and storm-surge overwash events can have long-term effects on vegetation and on soil and groundwater salinities, posing risks of habitat loss critical to native species. An early warning system is urgently needed to predict and prepare for the consequences of these climate-related impacts on both the short-term dynamics of salinity in the soil and groundwater and the long-term effects on vegetation. For this purpose, the U.S. Geological Survey’s spatially explicit model of vegetation community dynamics along coastal salinity gradients (MANHAM) is integrated into the USGS groundwater model (SUTRA) to create a coupled hydrology–salinity–vegetation model, MANTRA. In MANTRA, the uptake of water by plants is modeled as a fluid mass sink term. Groundwater salinity, water saturation and vegetation biomass determine the water available for plant transpiration. Formulations and assumptions used in the coupled model are presented. MANTRA is calibrated with salinity data and vegetation pattern for a coastal area of Florida Everglades vulnerable to storm surges. A possible regime shift at that site is investigated by simulating the vegetation responses to climate variability and disturbances, including SLR and storm surges based on empirical information.

  2. Stochastic Modeling of Vegetation Growth, Mortality and Invasion in a Fluvial Floodplain in Interaction with Floods

    NASA Astrophysics Data System (ADS)

    Miyamoto, Hitoshi; Toshimori, Nobuhiko; Kimura, Ryo

    2013-04-01

    Vegetation overgrowth in fluvial floodplains and sand bars has become a serious engineering problem for riparian management in Japan. From both viewpoints of flood control and ecological conservation, it would be necessary to predict the vegetation dynamics accurately for long-term duration. In this research, we have tried to develop a stochastic model for predicting the dynamics of trees in fluvial floodplains with emphasis on the interaction with flood impacts. The model consists of the following four components: (i) long-term stochastic behavior of flow discharge, (ii) hydrodynamics in a channel with floodplain vegetation, (iii) variation of riverbed topography, and (iv) vegetation dynamics on floodplains. In the model, the flood discharge is stochastically simulated using a filtered Poisson process, one of the conventional approaches in hydrological time-series generation. The modeling for vegetation dynamics includes the effects of tree growth, mortality by flood impacts, and infant tree invasion. Vegetation condition has been observed mainly before and after flood impacts since 2008 at a field site located between 23.2-24.0 km from the river mouth in Kako River, Japan. The Kako River has the catchment area of 1,730 km2 and the main channel length of 96 km. This site is one of the vegetation overgrowth locations in the Kako River floodplains, where the predominant tree species are willows and bamboos. In the field survey, the position, trunk diameter and height of each tree as well as the riverbed materials were measured after several flood events to investigate their impacts on the floodplain vegetation community. In this presentation, the three effects in vegetation dynamics, i.e., the tree growth rate, mortality, and infant tree invasion, are refined for improving the model predictability. The growth rate curve proposed here is derived by introducing inhibition effect of larger trees into the conventional Richards growth curve. As for the mortality rate

  3. Investigation of North American vegetation variability under recent climate - A study using the SSiB4/TRIFFID biophysical/dynamic vegetation model

    NASA Astrophysics Data System (ADS)

    Zhang, Z.; Xue, Y.; MacDonald, G. M.; Cox, P. M.; Collatz, G. J.

    2014-12-01

    This study applies a 2-D biophysical model/dynamic vegetation model (SSiB4/TRIFFID) to investigate the dominant factors affecting vegetation equilibrium conditions, to assess the model's ability to simulate seasonal to decadal variability for the past 60 years (from 1948 through 2008), to analyze vegetation spatiotemporal characteristics over North America (NA), and to identify the relationships between vegetation and climate. Satellite data are employed as constraints for this study. The optimum temperature for photosynthesis, leaf drop threshold temperatures, and competition coefficients in the Lotka-Volterra equation have major impact on the vegetation spatial distribution and reach to equilibrium status in SSiB4/TRIFFID. The phenomenon that vegetation competition coefficients affect equilibrium suggests the importance of including biotic effects in dynamical vegetation modeling. SSiB4/TRIFFID can reproduce the features of NA distributions of dominant vegetation types, the vegetation fraction, and LAI, including its seasonal, interannual, and decadal variability, well compared with satellite-derived products. The NA LAI shows an increasing trend after the 1970s in responding to warming. Meanwhile, both simulation and satellite observations reveal LAI increased in the southeastern U.S. starting from the 1980s. The effects of the severe drought during 1987-1992 and the last decade in the southwestern U.S.on vegetation are also evident from the simulated and satellite-derived LAIs.Both simulated and satellite-derived LAIs have the strongest correlations with air temperature at northern middle to high latitudes in spring through their effect on photosynthesis and phenological processes. During the summer, the areas with positive correlations retreat northward. Meanwhile, in southwestern dry lands, the negative correlations appear due to the heat stress there during the summer. Furthermore, there are also positive correlations between soil wetness and LAI, which

  4. Comparison of the sensor dependence of vegetation indices and vegetation water indices based on radiative transfer model

    NASA Astrophysics Data System (ADS)

    Chen, Xiaoping; Wang, Shudong; Jiang, Hailing; Zhang, Xia

    2014-11-01

    The vegetation index (VI) and vegetation water index (VIw) have long been used for plant water stress detection indiscriminately, without considering the effects of differences in their band selection. To address this, this study quantitatively compared the difference of sensor dependence for the two indices based on canopy/atmospheric radiative transfer model. Five different bandwidths at canopy and top-of-atmosphere scale were simulated separately for 23 classic indices. The results show that VIws exhibited better correlation with vegetation water content (VWC) at both scale ( R2 : 0.835; 0.812) in comparison with VIs ( R2 : 0.474; 0.475). To quantitatively describe the uncertainty caused by bandwidth, a new index variability was established. VIws and VIs performed entirely differently: at canopy scale, the uncertainty caused by bandwidths for VIws and VIs is 13.703% and 43.451%, respectively. However, at top-of-atmosphere scale, the uncertainty for VIws and VIs is 32.021% and 41.265%. VIws exhibited less dependence on bandwidth and were more affected by atmospheric effect than VIs. We attribute these differences to differences in band selection: VIws based on water absorption features are more sensitive to not only variation of VWC but also atmospheric conditions. Conversely, as chlorophyll absorption features which VIs are calculated on effectively avoid atmospheric absorption features and are located in red edge region, VIs are found less affected by the atmosphere condition and extremely sensitive to bandwidth. Results figure out the differences we should focus on when we choose VI or VIw from different sensors for VWC retrieval.

  5. [Application of five atmospheric correction models for Landsat TM data in vegetation remote sensing].

    PubMed

    Song, Wei-wei; Guan, Dong-sheng

    2008-04-01

    Based on the Landsat TM image of northeast Guangzhou City and north Huizhou City on July 18, 2005, and compared with apparent reflectance model, five atmospheric correction models including four dark object subtraction models and 6S model were evaluated from the aspects of vegetation reflectance, surface reflectance, and normalized difference vegetation index (NDVI). The results showed that the dark object subtraction model DOS4 produced the highest accurate vegetation reflectance, and had the largest information loads for surface reflectance and NDVI, being the best for the atmospheric correction in the study areas. It was necessary to analyze and to compare different models to find out an appropriate model for atmospheric correction in the study of other areas.

  6. Consequences of introducing bryophytes and Arctic-shrubs in a land surface model with dynamical vegetation.

    NASA Astrophysics Data System (ADS)

    Druel, A.; Peylin, P.; Krinner, G.; Ciais, P.; Viovy, N.

    2016-12-01

    Recent developments of boreal vegetation in land surface models show the importance of new plant functional types for a better representation of physical and carbon cycle related processes in northern latitudes. In past climate transitions, shifts in northern vegetation played a crucial role, for example in the inception of the Last Glacial Maximum. With the current high-latitude warming, a greening of vegetation is observed, associated with increased shrub cover. It has thus become essential to include shifts in vegetation in models. In the ORCHIDEE land surface model with a dynamic vegetation, we introduced new parameterizations and processes associated to Arctic-shrubs, bryophytes (mosses and lichens) and boreal C3 grasses to simulate their effect on biomass, albedo, snow cover and soil thermal dynamic (including frozen soils). Specific competition and survival conditions are defined for these three plant functional types. Competition between herbaceous vegetation, shrubs and trees is based on available light. Survival conditions of shrubs include their protection from cold temperatures by snow, and the competition between C3 grasses and bryophytes depends especially on soil water-saturation conditions. The equilibrium fractional coverage of the three competing plant functional types is based on the net primary production. We compare the results from simulations with different configurations: 1) vegetation being either fixed prescribed from a satellite land cover map or dynamic and 2) plant functional types used being either the default settings of ORCHIDEE which include three different boreal tree types and one grassland type, or the latter plus the new boreal vegetation types. The simulations are run for the historical period and with an additional run of 100 years according to the RCP 4.5 and 8.5 climate scenarios. We evaluate the effect of new plant functional types on the vegetation distribution, and their consequences for energy, water and carbon fluxes

  7. Modeling vegetation reflectance from satellite and in-situ monitoring data

    NASA Astrophysics Data System (ADS)

    Zoran, Maria; Florin Zoran, Liviu; Ionescu Golovanov, Carmen; Dida, Adrian

    2010-05-01

    Vegetation can be distinguished using remote sensing data from most other (mainly inorganic) materials by virtue of its notable absorption in the red and blue segments of the visible spectrum, its higher green reflectance and, especially, its very strong reflectance in the near-IR. Different types of vegetation show often distinctive variability from one another owing to such parameters as leaf shape and size, overall plant shape, water content, and associated background (e.g., soil types and spacing of the plants (density of vegetative cover within the scene). Different three-dimensional numerical models explicitly represent the vegetation canopy and use numerical methods to calculate reflectance. These models are computationally intensive and are therefore not generally suited to the correction of satellite imagery containing millions of pixels. Physically based models do provide understanding and are potentially more robust in extrapolation. They consider the vegetation canopy to comprise thin layers of leaves, suspended in air like sediment particles in water forming a turbid medium. Monitoring of vegetation cover changes by remote sensing data is one of the most important applications of satellite imagery. Vegetation reflectance has variations with sun zenith angle, view zenith angle, and terrain slope angle. To provide corrections of these effects, for visible and near-infrared light, was used a three parameters model and developed a simple physical model of vegetation reflectance, by assuming homogeneous and closed vegetation canopy with randomly oriented leaves. Multiple scattering theory was used to extend the model to function for both near-infrared and visible light. This vegetation reflectance model may be used to correct satellite imagery for bidirectional and topographic effects. For two ASTER images over Cernica forested area, placed to the East of Bucharest town , Romania, acquired within minutes from one another ,a nadir and off-nadir for band 3

  8. Modelling the Diversity of Outer Planetary Systems

    NASA Technical Reports Server (NTRS)

    Lissauer, Jack J.; Levison, H. F.; Duncan, M. J.; DeVincenzi, Donald L. (Technical Monitor)

    1998-01-01

    The process of planetary growth is extremely complicated, involving a myriad of physical and chemical processes, many of which are poorly understood. The ultimate configuration that a planetary system attains depends upon the properties of the disk out of which it grew, of the star at the center of the disk and, at least in some cases, of the interstellar environment. In an effort to numerically survey the possible diversity of planetary systems, we have constructed synthetic systems of giant planets and integrated their orbits to determine the dynamical lifetimes and thus the viability of these systems. Our construction algorithm begins with 110 -- 180 planetesimals located between 4 and 40 AU from a one solar mass star; most initial planetesimals have masses several tenths that of Earth. We integrate the orbits of these bodies subject to mutual gravitational perturbations and -as drag for 10(exp 6) - 10(exp 7) years, merging any pair of planetesimals which pass within one-tenth of a Hill Sphere of one another and adding "gas" to embryos larger than 10 Earth masses. Use of such large planetesimal radii provided sufficient damping to prevent the system from excessive dynamical heating. Subsequently, systems were evolved without gas drag, either with the enlarged radii or with more realistic radii. Systems took from a few million years to greater than ten billion years to become stable (10(exp 9) years without mergers of ejections). Some of the systems produced with the enlarged radii closely resemble our outer Solar System. Many systems contained only Uranus-mass objects. Encounters in simulations using realistic radii resulted in ejections, typically leaving only a few planets per system, most of which were on very eccentric orbits. Some of the systems that we constructed were stable for at least a billion years despite undergoing macroscopic orbital changes on much shorter timescales.

  9. 6-n-propylthiouracil taster status not related to reported cruciferous vegetable intake among ethnically diverse children

    USDA-ARS?s Scientific Manuscript database

    Sensitivity to the taste of 6-n-propylthiouracil (PROP) (a bitter chemical related to the phenylthiocarbamide found in cruciferous vegetables) has been related to dietary intake or preferences of cruciferous vegetables among adults and young children but not middle-aged children or adolescents. We h...

  10. Linking riparian dynamics and groundwater: an ecohydrologic approach to modeling groundwater and riparian vegetation.

    PubMed

    Baird, Kathryn J; Stromberg, Juliet C; Maddock, Thomas

    2005-10-01

    The growing use of global freshwater supplies is increasing the need for improved modeling of the linkage between groundwater and riparian vegetation. Traditional groundwater models such as MODFLOW have been used to predict changes in regional groundwater levels, and thus riparian vegetation potential attributable to anthropogenic water use. This article describes an approach that improves on these modeling techniques through several innovations. First, evapotranspiration from riparian/wetland systems is modeled in a manner that more realistically reflects plant ecophysiology and vegetation complexity. In the authors' model programs (RIP-ET and PRE-RIP-ET), the single, monotonically increasing evapotranspiration flux curve in traditional groundwater models is replaced with a set of ecophysiologically based curves, one for each plant functional group present. For each group, the curve simulates transpiration declines that occur both as water levels decline below rooting depths and as waters rise to levels that produce anoxic soil conditions. Accuracy is further improved by more effective spatial handling of vegetation distribution, which allows modeling of surface elevation and depth to water for multiple vegetation types within each large model cell. The use of RIP-ET in groundwater models can improve the accuracy of basin scale estimates of riparian evapotranspiration rates, riparian vegetation water requirements, and water budgets. Two case studies are used to demonstrate that RIP-ET produces significantly different evapotranspiration estimates than the traditional method. When combined with vegetation mapping and a supporting program (RIP-GIS), RIP-ET also enables predictions of riparian vegetation response to water use and development scenarios. The RIP-GIS program links the head distribution from MODFLOW with surface digital elevation models, producing moderate- to high-resolution depth-to-groundwater maps. Together with information on plant rooting depths

  11. 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.

  12. A fully traits-based approach to modeling global vegetation distribution

    PubMed Central

    van Bodegom, Peter M.; Douma, Jacob C.; Verheijen, Lieneke M.

    2014-01-01

    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. PMID:25225413

  13. A Hydrological Model for Predicting the Effects of Dams on the Shoreline Vegetation of Lakes and Reservoirs

    PubMed

    Hill; Keddy; Wisheu

    1998-09-01

    / The species richness of shoreline vegetation of unregulated lakes in Nova Scotia, Canada, is known to increase as a function of catchment area, a topographic variable governing water level fluctuations. Predictions based on catchment area however, fail to account for richness patterns at the margins of lakes enlarged by dams. Here, we compare the vegetation and hydrological regimes of regulated and unregulated systems. Hydrological regimes of regulated systems deviated from natural systems of similar catchment area by being either hypovariable or hypervariable for both within-year and among-year fluctuations in water level. Plant communities of dammed systems were less diverse, contained more exotic species, and were, with one exception, devoid of rare shoreline herbs. Data from "recovering," or previously dammed systems indicated that shoreline communities can be restored upon return of the appropriate hydrological regime. Using observed within-year and among-year water level fluctuation data, we propose a general model for the maintenance or restoration of diverse herbaceous wetlands on shorelines of temperate lakes or reservoirs. Managers can manipulate the within-year water level variation within prescribed limits (1-2 m), while ensuring that among-year variation (SD of summer levels) is less than 25% of within-year variation. This preliminary model is based on data from low-fertility, temperate lakes in river systems. To calibrate the model, plant community data from other regions are needed, as are long-term water-level data for unregulated lakes, data which are essential but largely lacking in many areas.KEY WORDS: Catchment area; Regulated lakes; Shoreline restoration; Rare plants; Exotic plants; Diversity

  14. The importance of volumetric canopy morphology when modelling drag around riparian vegetation

    NASA Astrophysics Data System (ADS)

    Boothroyd, Richard; Hardy, Richard; Warburton, Jeff; Marjoribanks, Timothy

    2017-04-01

    Riparian vegetation has a significant impact on the hydraulic functioning of river systems. The bulk of past work concerned with modelling the influence of vegetation on flow has considered vegetation to be morphologically simple, and has generally neglected the complexity and porosity of natural plants, defined herein as the volumetric canopy morphology. However, the volumetric canopy morphology can influence the mean and turbulent properties of the flow, producing spatially heterogeneous downstream velocity fields. By explicitly accounting for this in a computational fluid dynamics (CFD) model, and representing the plant as a porous blockage, complex flow structures and drag can be modelled. For a riparian species, Hebe odora, good agreement with flume measurements are found. Plant shear layer turbulence is shown to be dominated by Kelvin-Helmholtz and Görtler-type vortices, generated through shear instability. Porous representations of the plants, that allow for flow to pass through the plant canopy interior, are compared against fully impermeable plant representations. Penetration of fluid through the canopy in the porous case resembles 'bleed-flow', and this results in a plant wake region that significantly differs from the impermeable case, which is characteristic of wake flow around a traditional bluff body. These results demonstrate the significant effect that the volumetric canopy morphology and porosity of natural plants has on the three-dimensional flow and in-stream drag, and enables a re-evaluation of vegetative flow resistance. The modelled results allow a species dependent Manning's n to be calculated, and this presents an opportunity to move away from the conventional methods of representing vegetation in hydraulic models, in favour of a more physically determined approach. Given the importance of vegetation in river corridor management, and the increasing application of UAV imagery to map riparian vegetation, the numerical scheme developed here

  15. Assessing environmental drivers of vegetation greenness by integrating multiple earth observation data in the LPJmL dynamic global vegetation model

    NASA Astrophysics Data System (ADS)

    Forkel, Matthias; Carvalhais, Nuno; Schaphoff, Sibyll; von Bloh, Werner; Thurner, Martin; Thonicke, Kirsten

    2014-05-01

    Recently produced satellite datasets of vegetation greenness demonstrate a widespread greening of the earth in the last three decades. These positive trends in vegetation greenness are related to changes in leaf area, vegetation cover and photosynthetic activity. Climatic changes, CO2 fertilization, disturbances and other land cover changes are potential drivers of these greening trends. Nevertheless, different satellite datasets show different magnitudes and trends in vegetation greenness. This fact raises the question about the reliability of these datasets. On the other hand, global vegetation models can be potentially used to assess the effects of environmental drivers on vegetation greenness and thus to explore the environmental reliability of these datasets. Unfortunately, current vegetation models have several weaknesses in reproducing observed temporal dynamics in vegetation greenness. Our aim is to integrate multiple earth observation data sets in a dynamic global vegetation model in order to 1) improve the model's capability to reproduce observed dynamics and spatial patterns of vegetation greenness and 2) to assess the spatial and temporal importance of environmental drivers for the seasonal to decadal variability of vegetation greenness. For this purpose, we developed a data integration system for the LPJmL dynamic global vegetation model (LPJmL-DIS). We implemented a new phenology scheme in LPJmL to better represent observed temporal dynamics of FAPAR (fraction of absorbed photosynthetic active radiation). Model parameters were globally optimized using a genetic optimization algorithm. The model optimization was performed globally against 30 year FAPAR time series (GIMMS3g dataset), against 10 year albedo time series (MODIS) and global patterns of gross primary production as up-scaled from FLUXNET eddy covariance measurements. Additionally, we directly prescribed satellite observations of land and tree cover in LPJmL to better represent global

  16. From terrestrial to aquatic fluxes: Integrating stream dynamics within a dynamic global vegetation modeling framework

    NASA Astrophysics Data System (ADS)

    Hoy, Jerad; Poulter, Benjamin; Emmett, Kristen; Cross, Molly; Al-Chokhachy, Robert; Maneta, Marco

    2016-04-01

    Integrated terrestrial ecosystem models simulate the dynamics and feedbacks between climate, vegetation, disturbance, and hydrology and are used to better understand biogeography and biogeochemical cycles. Extending dynamic vegetation models to the aquatic interface requires coupling surface and sub-surface runoff to catchment routing schemes and has the potential to enhance how researchers and managers investigate how changes in the environment might impact the availability of water resources for human and natural systems. In an effort towards creating such a coupled model, we developed catchment-based hydrologic routing and stream temperature model to pair with LPJ-GUESS, a dynamic global vegetation model. LPJ-GUESS simulates detailed stand-level vegetation dynamics such as growth, carbon allocation, and mortality, as well as various physical and hydrologic processes such as canopy interception and through-fall, and can be applied at small spatial scales, i.e., 1 km. We demonstrate how the coupled model can be used to investigate the effects of transient vegetation dynamics and CO2 on seasonal and annual stream discharge and temperature regimes. As a direct management application, we extend the modeling framework to predict habitat suitability for fish habitat within the Greater Yellowstone Ecosystem, a 200,000 km2 region that provides critical habitat for a range of aquatic species. The model is used to evaluate, quantitatively, the effects of management practices aimed to enhance hydrologic resilience to climate change, and benefits for water storage and fish habitat in the coming century.

  17. Evaluation of Vegetation Biomass in CMIP5 Models over the Northern High-Latitudes

    NASA Astrophysics Data System (ADS)

    Yang, C. E.; Mao, J.; Hoffman, F. M.; Ricciuto, D. M.; Fu, J. S.

    2015-12-01

    Global vegetation biomass stores huge amounts of carbon and is thus important to the global carbon budget. For the past few decades, different observation-based estimates and modeling of biomass in above- and below-ground vegetation components have been comprehensively conducted. However, uncertainties still exist, in particular for the simulation of biomass magnitude, tendency, and the response of biomass to natural and anthropogenic drivers. To elucidate these uncertainties, this study compares vegetation biomass of sixteen Earth System Models (ESMs) from the Coupled Model Intercomparison Project Phase 5 (CMIP5) archive with latest observation-based data over the Northern High-Latitudes. Results demonstrate that the models exhibit large variability of vegetation biomass, and the model ensemble mean underestimates temperate forest total biomass but overestimates boreal forest total biomass compared to the observational data. Moreover, both the model outputs and the observational data show individual biomass components are highly sensitive to the change of precipitation across different biomes. Possible causes behind inter-model and model-observation differences, such as the discrepancies of climatic conditions, the carbon allocation schemes, prescribed vegetation distributions, representation of disturbances as well as spin-up processes in the ESMs, are investigated and will be discussed.

  18. 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.

  19. New progress in study on vegetation models for hyperspectral remote sensing

    NASA Astrophysics Data System (ADS)

    Tong, Qingxi; Zhao, Yongchao; Zhang, Xia; Zhang, Bing; Zheng, Lanfen

    2001-02-01

    Some new vegetation models for hyperspectral remote sensing are provided in this paper. They are Derivative Spectral Model (DSM), Multi-temporal Index Image Cube Model (MIIC), Hybrid Decision Tree Model (HDT) and Correlation Simulating Analysis Model (CSAM). All models are developed and used to process the images acquired by Airborne Pushbroom Hyperspectral Imager (PHI) in Changzhou area, China, 1999. Some successful applications are provided and evaluated. The results show that DSM has the ability of eliminating the background interference of vegetation analysis. MIIC is a viable method for monitoring dynamic change of land cover and vegetation growth stages. HDT is effective in precise classification of rice land while CSAM provide a possibility and theoretical basis for crop identification, breed classification, and land information extraction especially for rice.

  20. Comparison between remote sensing and a dynamic vegetation model for estimating terrestrial primary production of Africa.

    PubMed

    Ardö, Jonas

    2015-12-01

    Africa is an important part of the global carbon cycle. It is also a continent facing potential problems due to increasing resource demand in combination with climate change-induced changes in resource supply. Quantifying the pools and fluxes constituting the terrestrial African carbon cycle is a challenge, because of uncertainties in meteorological driver data, lack of validation data, and potentially uncertain representation of important processes in major ecosystems. In this paper, terrestrial primary production estimates derived from remote sensing and a dynamic vegetation model are compared and quantified for major African land cover types. Continental gross primary production estimates derived from remote sensing were higher than corresponding estimates derived from a dynamic vegetation model. However, estimates of continental net primary production from remote sensing were lower than corresponding estimates from the dynamic vegetation model. Variation was found among land cover classes, and the largest differences in gross primary production were found in the evergreen broadleaf forest. Average carbon use efficiency (NPP/GPP) was 0.58 for the vegetation model and 0.46 for the remote sensing method. Validation versus in situ data of aboveground net primary production revealed significant positive relationships for both methods. A combination of the remote sensing method with the dynamic vegetation model did not strongly affect this relationship. Observed significant differences in estimated vegetation productivity may have several causes, including model design and temperature sensitivity. Differences in carbon use efficiency reflect underlying model assumptions. Integrating the realistic process representation of dynamic vegetation models with the high resolution observational strength of remote sensing may support realistic estimation of components of the carbon cycle and enhance resource monitoring, providing suitable validation data is available.

  1. Optimum vegetation characteristics, assimilation, and transpiration during a dry season: 1. Model description

    NASA Astrophysics Data System (ADS)

    van der Tol, C.; Meesters, A. G. C. A.; Dolman, A. J.; Waterloo, M. J.

    2008-03-01

    This paper presents a model to predict optimum vegetation characteristics in water stressed conditions. Starting point is the principle of homeostasis of water flow through the soil-vegetation-atmosphere continuum. Combining this with a biochemical model for photosynthesis, a relationship between photosynthetic capacity, stomatal regulation, and hydraulic properties of the vegetation is derived. Optimum photosynthetic capacity and internal carbon dioxide concentration are calculated using the assumption that growth is maximized. This optimality hypothesis is applied for three scenarios which are increasingly realistic. Optimum parameters reflect a strategy to deal with two tradeoffs: the trade-off between fast growth and avoidance of drought and between a high photosynthetic capacity and avoidance of high respiration losses. The theory predicts general boundary conditions for growth but does not consider effects of competition between species, fires, pest, and diseases or other limitations that occur locally. In a companion paper the theory is evaluated using a data set collected in sub-Mediterranean vegetation.

  2. Modeling of vegetation canopy reflectance: Status, issues and recommended future strategy

    NASA Technical Reports Server (NTRS)

    Goel, N. S. (Editor)

    1982-01-01

    Various technical issues related to mapping of vegetative type, condition and stage of maturity, utilizing remotely sensed spectral data are reviewed. The existing knowledge base of models, especially of radiative properties of the vegetation canopy and atmosphere, is reviewed to establish the state of the art for addressing the problem of vegetation mapping. Activities to advance the state of the art are recommended. They include working on canopy reflectance and atmospheric scattering models, and field measurements of canopy reflectance as well as of canopy components. Leaf area index (LAI) and solar radiation interception (SRI) are identified as the two most important vegetation variables requiring further investigation. It is recommended that activities related to sensing them or understanding their relationships with measurable variables, should be encouraged and supported.

  3. New Models for Reaching Diverse Learners.

    ERIC Educational Resources Information Center

    Dew, Debra R.; Waggoner, Jan E.

    This paper reports on the influence of a graduate course, "Methods for Masters," designed to broaden the pedagogical repertoires of cooperating teachers by providing experience in six instructional models (cooperative learning, concept attainment, group investigation, learning contracts, simulations, and synectics). The course used…

  4. Characterising Vegetation Canopies by means of optical data and Microwave Scattering models

    NASA Astrophysics Data System (ADS)

    Molina, Iñigo; Gonzalez, Constancio; Ormeño, Santiago; Morillo, Carmen; Garcia-Melendez, Eduardo

    One of the main strengths of active microwave remote sensing, in relation to frequency, is its capacity to penetrate vegetation canopies, and reach the ground surface, so that information about the vegetation and hydrological properties of the surface can be drawn. All this infor-mation is gathered in the so called backscattering coefficient (σ 0 ), and in a vegetated medium, this coefficient reveals important information on the vegetation water content, geometry and/or structure of the canopy elements, above ground biomass, and soil roughness and moisture. In the scope of microwave frequencies, modeling the backscattering coefficient of vegetated terrain, involves taking into account scattering models that simulate the soil surface contribution by means of its physical variables, and the vegetation layer, through the knowledge of its biophys-ical properties. Soil surface scattering models require describing parameters of roughness, like soil profile height displacement standard deviation and correlation length, and moisture, which determines sur-face reflective properties. The knowledge of these parameters, allows to establishing surface scattering models with different validity ranges. Some frequently used models are divided into theoretical and empirical models. The vegetation canopy is usually regarded as a homogeneous, or random layer, at a certain height above terrain surface, and it is used to compute the attenuation through this layer. This requires a geometric generalization of the vegetation layer and its constituents, specifying additionally its electromagnetic properties. The main simulation models are based on Radiative Transfer theory, which allows for different approaches and simplifications. In this sense, somo of these models, can be efficiently adapted to any vegetated medium, and the constituents can by approximated by more general variables like Leaf Area Index (LAI), or Water total Content (WTC) of Vegetation. Moreover, in the microwave region

  5. Subcanopy Solar Radiation Model: an irradiation model for predicting light in heavily vegetated landscapes

    NASA Astrophysics Data System (ADS)

    Bode, C. A.; Limm, M. P.; Finlay, J. C.; Power, M.

    2012-12-01

    Solar radiation flux, irradiance, affects many biological (e.g. photosynthesis, germination, metabolism) and hydrological (e.g. snow melt, water cycling) processes. Models of these processes often require data at the watershed scale. GIS based solar models that predict irradiation at the watershed scale take topographic shading into account, but do not account for vegetative shading. Methods that quantify subcanopy irradiation do so only at a single point. Further, calibrating the subcanopy models require significant field effort and knowledge of individual species characteristics (leaf area index, mean leaf angle, clumping factor, etc.). Upscaling from point values to watersheds is a significant source of uncertainty. We propose an approach to modeling irradiation that uses airborne LiDAR to estimate canopy openness as a Light Penetration Index (LPI). We coupled LPI with the GRASS GIS r.sun solar model to produce the Subcanopy Solar Radiation model (SSR). SSR accounts for both topographic shading and vegetative shading at the watershed scale. Output is 52 raster maps (one per week) of 24 hours of irradiation (watt-hours/m2). We calibrated the r.sun model to a weather station at our field site and to field measurements of direct and diffuse solar radiation taken for 24 hours at the weather station site. We validate predictions of the SSR by comparing modeled output to field measurements and to a standard method for point estimation of subcanopy radiation, hemispherical photographs processed with Gap Light Analyzer 2.0 (GLA). Based on ANCOVA analysis, SSR and GLA models exhibit a similar linear relationship with field data, and the models predict similar total solar radiation flux across the range of canopy openness. With similar quality to a standard point method, but with greatly expanded spatial coverage, SSR should become a useful tool in watershed analysis.

  6. Thresholds in vegetation responses to drought: Implications for rainfall-runoff modeling

    NASA Astrophysics Data System (ADS)

    Tague, C.; Dugger, A. L.

    2011-12-01

    While threshold behavior is often associated with soil and subsurface runoff generation, dynamic vegetation responses to water stress may be an important contributor to threshold type behavior in rainfall runoff models. Vegetation water loss varies with vegetation type and biomass and transpiration dynamics in many settings are regulated by stomatal function. In water limited environments the timing and frequency of stomatal closure varies from year to year as a function of water stress. Stomatal closure and associated fine time scale (hourly to weekly) plant transpiration may appear as threshold (on/off) behavior. Total seasonal to annual plant water use, however, typically show a continuous relationship with atmospheric conditions and soil moisture. Thus while short-time scale behavior may demonstrate non-linear, threshold type behavior, continuous relationships at slightly longer time scales can be used to capture the role of vegetation mediated water loss and its associated impact on storage and runoff. Many rainfall runoff models rely on these types of relationships. However these relationships may change if water stress influences vegetation structure as it does in drought conditions. Forest dieback under drought is a dramatic example of a threshold event, and one that is expected to occur with increasing frequency under a warmer climate. Less dramatic but still important are changes in leaf and root biomass in response to drought. We demonstrate these effects using a coupled ecosystem carbon cycling and hydrology model and show that by accounting for drought driven changes in vegetation dynamics we improve our ability to capture inter-annual variation in streamflow for a semi-arid watershed in New Mexico. We also use the model to predict spatial patterns of more catastrophic vegetation dieback with moisture stress and show that we can accurately capture the spatial pattern of ponderosa pine dieback during a early 2000s drought in New Mexico. We use these

  7. Investigation of North American vegetation variability under recent climate: A study using the SSiB4/TRIFFID biophysical/dynamic vegetation model

    NASA Astrophysics Data System (ADS)

    Zhang, Zhengqiu; Xue, Yongkang; MacDonald, Glen; Cox, Peter M.; Collatz, G. James

    2015-02-01

    Recent studies have shown that current dynamic vegetation models have serious weaknesses in reproducing the observed vegetation dynamics and contribute to bias in climate simulations. This study intends to identify the major factors that underlie the connections between vegetation dynamics and climate variability and investigates vegetation spatial distribution and temporal variability at seasonal to decadal scales over North America (NA) to assess a 2-D biophysical model/dynamic vegetation model's (Simplified Simple Biosphere Model version 4, coupled with the Top-down Representation of Interactive Foliage and Flora Including Dynamics Model (SSiB4/TRIFFID)) ability to simulate these characteristics for the past 60 years (1948 through 2008). Satellite data are employed as constraints for the study and to compare the relationships between vegetation and climate from the observational and the simulation data sets. Trends in NA vegetation over this period are examined. The optimum temperature for photosynthesis, leaf drop threshold temperatures, and competition coefficients in the Lotka-Volterra equation, which describes the population dynamics of species competing for some common resource, have been identified as having major impacts on vegetation spatial distribution and obtaining proper initial vegetation conditions in SSiB4/TRIFFID. The finding that vegetation competition coefficients significantly affect vegetation distribution suggests the importance of including biotic effects in dynamical vegetation modeling. The improved SSiB4/TRIFFID can reproduce the main features of the NA distributions of dominant vegetation types, the vegetation fraction, and leaf area index (LAI), including its seasonal, interannual, and decadal variabilities. The simulated NA LAI also shows a general increasing trend after the 1970s in responding to warming. Both simulation and satellite observations reveal that LAI increased substantially in the southeastern U.S. starting from the 1980

  8. Development of JPSS VIIRS Global Gridded Vegetation Index products for NOAA NCEP Environmental Modeling Systems

    NASA Astrophysics Data System (ADS)

    Vargas, Marco; Miura, Tomoaki; Csiszar, Ivan; Zheng, Weizhong; Wu, Yihua; Ek, Michael

    2017-04-01

    The first Joint Polar Satellite System (JPSS) mission, the Suomi National Polar-orbiting Partnership (S-NPP) satellite, was successfully launched in October, 2011, and it will be followed by JPSS-1, slated for launch in 2017. JPSS provides operational continuity of satellite-based observations and products for NOAA's Polar Operational Environmental Satellites (POES). Vegetation products derived from satellite measurements are used for weather forecasting, land modeling, climate research, and monitoring the environment including drought, the health of ecosystems, crop monitoring and forest fires. The operationally produced S-NPP VIIRS Vegetation Index (VI) Environmental Data Record (EDR) includes two vegetation indices: the Top of the Atmosphere (TOA) Normalized Difference Vegetation Index (NDVI), and the Top of the Canopy (TOC) Enhanced Vegetation Index (EVI). For JPSS-1, the S-NPP Vegetation Index EDR algorithm has been updated to include the TOC NDV. The current JPSS operational VI products are generated in granule style at 375 meter resolution at nadir, but these products in granule format cannot be ingested into NOAA operational monitoring and decision making systems. For that reason, the NOAA JPSS Land Team is developing a new global gridded Vegetation Index (VI) product suite for operational use by the NOAA National Centers for Environmental Prediction (NCEP). The new global gridded VIs will be used in the Multi-Physics (MP) version of the Noah land surface model (Noah-MP) in NCEP NOAA Environmental Modeling System (NEMS) for plant growth and data assimilation and to describe vegetation coverage and density in order to model the correct surface energy partition. The new VI 4km resolution global gridded products (TOA NDVI, TOC NDVI and TOC EVI) are being designed to meet the needs of directly ingesting vegetation index variables without the need to develop local gridding and compositing procedures. These VI products will be consistent with the already

  9. Modeling Pacific Northwest carbon and water cycling using CARAIB Dynamic Vegetation Model

    NASA Astrophysics Data System (ADS)

    Dury, M.; Kim, J. B.; Still, C. J.; Francois, L. M.; Jiang, Y.

    2015-12-01

    While uncertainties remain regarding projected temperature and precipitation changes, climate warming is already affecting ecosystems in the Pacific Northwest (PNW). Decrease in ecosystem productivity as well as increase in mortality of some plant species induced by drought and disturbance have been reported. Here, we applied the process-based dynamic vegetation model CARAIB to PNW to simulate the response of water and carbon cycling to current and future climate change projections. The vegetation model has already been successfully applied to Europe to simulate plant physiological response to climate change. We calibrated CARAIB to PNW using global Plant Functional Types. For calibration, the model is driven with the gridded surface meteorological dataset UIdaho MACA METDATA with 1/24-degree (~4-km) resolution at a daily time step for the period 1979-2014. The model ability to reproduce the current spatial and temporal variations of carbon stocks and fluxes was evaluated using a variety of available datasets, including eddy covariance and satellite observations. We focused particularly on past severe drought and fire episodes. Then, we simulated future conditions using the UIdaho MACAv2-METDATA dataset, which includes downscaled CMIP5 projections from 28 GCMs for RCP4.5 and RCP8.5. We evaluated the future ecosystem carbon balance resulting from changes in drought frequency as well as in fire risk. We also simulated future productivity and drought-induced mortality of several key PNW tree species.

  10. Development of full regeneration establishment models for the forest vegetation simulator

    Treesearch

    John D. Shaw

    2015-01-01

    For most simulation modeling efforts, the goal of model developers is to produce simulations that are the best representations of realism as possible. Achieving this goal commonly requires a considerable amount of data to set the initial parameters, followed by validation and model improvement – both of which require even more data. The Forest Vegetation Simulator (FVS...

  11. Analysis of vegetation effect on waves using a vertical 2-D RANS model

    USDA-ARS?s Scientific Manuscript database

    A vertical two-dimensional (2-D) model has been applied in the simulation of wave propagation through vegetated water bodies. The model is based on an existing model SOLA-VOF which solves the Reynolds-Averaged Navier-Stokes (RANS) equations with the finite difference method on a staggered rectangula...

  12. Using a LIDAR Vegetation Model to Predict UHF SAR Attenuation in Coniferous Forests

    PubMed Central

    Swanson, Alan; Huang, Shengli; Crabtree, Robert

    2009-01-01

    Attenuation of radar signals by vegetation can be a problem for target detection and GPS reception, and is an important parameter in models describing vegetation backscatter. Here we first present a model describing the 3D distribution of stem and foliage structure based on small footprint scanning LIDAR data. Secondly we present a model that uses ray-tracing methodology to record detailed interactions between simulated radar beams and vegetation components. These interactions are combined over the SAR aperture and used to predict two-way attenuation of the SAR signal. Accuracy of the model is demonstrated using UHF SAR observations of large trihedral corner reflectors in coniferous forest stands. Our study showed that the model explains between 66% and 81% of the variability in observed attenuation. PMID:22573972

  13. Using a LIDAR Vegetation Model to Predict UHF SAR Attenuation in Coniferous Forests.

    PubMed

    Swanson, Alan; Huang, Shengli; Crabtree, Robert

    2009-01-01

    Attenuation of radar signals by vegetation can be a problem for target detection and GPS reception, and is an important parameter in models describing vegetation backscatter. Here we first present a model describing the 3D distribution of stem and foliage structure based on small footprint scanning LIDAR data. Secondly we present a model that uses ray-tracing methodology to record detailed interactions between simulated radar beams and vegetation components. These interactions are combined over the SAR aperture and used to predict two-way attenuation of the SAR signal. Accuracy of the model is demonstrated using UHF SAR observations of large trihedral corner reflectors in coniferous forest stands. Our study showed that the model explains between 66% and 81% of the variability in observed attenuation.

  14. Investigation of North American Vegetation Variability under Recent Climate: A Study Using the SSiB4/TRIFFID Biophysical/Dynamic Vegetation Model

    NASA Technical Reports Server (NTRS)

    Zhang, Zhengqiu; Xue, Yongkang; MacDonald, Glen; Cox, Peter M.; Collatz, George J.

    2015-01-01

    Recent studies have shown that current dynamic vegetation models have serious weaknesses in reproducing the observed vegetation dynamics and contribute to bias in climate simulations. This study intends to identify the major factors that underlie the connections between vegetation dynamics and climate variability and investigates vegetation spatial distribution and temporal variability at seasonal to decadal scales over North America (NA) to assess a 2-D biophysical model/dynamic vegetation model's (Simplified Simple Biosphere Model version 4, coupled with the Top-down Representation of Interactive Foliage and Flora Including Dynamics Model (SSiB4/TRIFFID)) ability to simulate these characteristics for the past 60 years (1948 through 2008). Satellite data are employed as constraints for the study and to compare the relationships between vegetation and climate from the observational and the simulation data sets. Trends in NA vegetation over this period are examined. The optimum temperature for photosynthesis, leaf drop threshold temperatures, and competition coefficients in the Lotka-Volterra equation, which describes the population dynamics of species competing for some common resource, have been identified as having major impacts on vegetation spatial distribution and obtaining proper initial vegetation conditions in SSiB4/TRIFFID. The finding that vegetation competition coefficients significantly affect vegetation distribution suggests the importance of including biotic effects in dynamical vegetation modeling. The improved SSiB4/TRIFFID can reproduce the main features of the NA distributions of dominant vegetation types, the vegetation fraction, and leaf area index (LAI), including its seasonal, interannual, and decadal variabilities. The simulated NA LAI also shows a general increasing trend after the 1970s in responding to warming. Both simulation and satellite observations reveal that LAI increased substantially in the southeastern U.S. starting from the 1980

  15. Succession of Bacterial Community Structure and Diversity in Soil along a Chronosequence of Reclamation and Re-Vegetation on Coal Mine Spoils in China

    PubMed Central

    Li, Yuanyuan; Wen, Hongyu; Chen, Longqian; Yin, Tingting

    2014-01-01

    The growing concern about the effectiveness of reclamation strategies has motivated the evaluation of soil properties following reclamation. Recovery of belowground microbial community is important for reclamation success, however, the response of soil bacterial communities to reclamation has not been well understood. In this study, PCR-based 454 pyrosequencing was applied to compare bacterial communities in undisturbed soils with those in reclaimed soils using chronosequences ranging in time following reclamation from 1 to 20 year. Bacteria from the Proteobacteria, Chloroflexi, Actinobacteria, Acidobacteria, Planctomycetes and Bacteroidetes were abundant in all soils, while the composition of predominant phyla differed greatly across all sites. Long-term reclamation strongly affected microbial community structure and diversity. Initial effects of reclamation resulted in significant declines in bacterial diversity indices in younger reclaimed sites (1, 8-year-old) compared to the undisturbed site. However, bacterial diversity indices tended to be higher in older reclaimed sites (15, 20-year-old) as recovery time increased, and were more similar to predisturbance levels nearly 20 years after reclamation. Bacterial communities are highly responsive to soil physicochemical properties (pH, soil organic matter, Total N and P), in terms of both their diversity and community composition. Our results suggest that the response of soil microorganisms to reclamation is likely governed by soil characteristics and, indirectly, by the effects of vegetation restoration. Mixture sowing of gramineae and leguminosae herbage largely promoted soil geochemical conditions and bacterial diversity that recovered to those of undisturbed soil, representing an adequate solution for soil remediation and sustainable utilization for agriculture. These results confirm the positive impacts of reclamation and vegetation restoration on soil microbial diversity and suggest that the most important

  16. Succession of bacterial community structure and diversity in soil along a chronosequence of reclamation and re-vegetation on coal mine spoils in China.

    PubMed

    Li, Yuanyuan; Wen, Hongyu; Chen, Longqian; Yin, Tingting

    2014-01-01

    The growing concern about the effectiveness of reclamation strategies has motivated the evaluation of soil properties following reclamation. Recovery of belowground microbial community is important for reclamation success, however, the response of soil bacterial communities to reclamation has not been well understood. In this study, PCR-based 454 pyrosequencing was applied to compare bacterial communities in undisturbed soils with those in reclaimed soils using chronosequences ranging in time following reclamation from 1 to 20 year. Bacteria from the Proteobacteria, Chloroflexi, Actinobacteria, Acidobacteria, Planctomycetes and Bacteroidetes were abundant in all soils, while the composition of predominant phyla differed greatly across all sites. Long-term reclamation strongly affected microbial community structure and diversity. Initial effects of reclamation resulted in significant declines in bacterial diversity indices in younger reclaimed sites (1, 8-year-old) compared to the undisturbed site. However, bacterial diversity indices tended to be higher in older reclaimed sites (15, 20-year-old) as recovery time increased, and were more similar to predisturbance levels nearly 20 years after reclamation. Bacterial communities are highly responsive to soil physicochemical properties (pH, soil organic matter, Total N and P), in terms of both their diversity and community composition. Our results suggest that the response of soil microorganisms to reclamation is likely governed by soil characteristics and, indirectly, by the effects of vegetation restoration. Mixture sowing of gramineae and leguminosae herbage largely promoted soil geochemical conditions and bacterial diversity that recovered to those of undisturbed soil, representing an adequate solution for soil remediation and sustainable utilization for agriculture. These results confirm the positive impacts of reclamation and vegetation restoration on soil microbial diversity and suggest that the most important

  17. Stressed deserts: A new vegetation/sediment-transport model for dryland environments

    NASA Astrophysics Data System (ADS)

    Mayaud, Jerome; Bailey, Richard; Wiggs, Giles

    2016-04-01

    In many drylands, vegetation is patchy and dynamic through time and space, with complex ecohydrological feedbacks and plant-plant interactions leading to the emergence of characteristic vegetation patterning. There is increasing evidence that information from the patterns themselves can be used as indicators of a dryland system's proximity to collapse. However, current models simulating the evolution of these vegetation patterns do not account for their effects on wind flow and on the entrainment, transport and redistribution of wind-blown material. Significant uncertainty therefore remains about how these vulnerable landscapes will react to increasing climate forcing and land-use pressure over the 21st century and beyond. We present the coupled Vegetation and Sediment TrAnsport model (ViSTA), a new, multi-scale cellular automaton model designed to simulate transport in vegetated dryland contexts. The model is parameterised using empirical data collected during a field campaign in Namibia that sought to investigate the impact of desert vegetation on wind speed and turbulence at the surface. A new turbulence-based model for aeolian transport is also used to drive the movement of sediment within ViSTA. We show that this coupled approach allows for realistic simulations of dynamics at both the bedform and landscape scale. It is especially important to understand the geomorphological responses of vegetated semi-arid landscapes to a variety of simulated stresses, since these regions are often heavily used for pastoralism, agriculture and habitation. In characterising possible transition scenarios between patterned and desert states, the ViSTA model therefore represents a powerful tool that has direct relevance to land management policies in highly vulnerable environments.

  18. Implementing Perennial Kitchen Garden Model to Improve Diet Diversity in Melghat, India

    PubMed Central

    Birdi, Tannaz J.; Shah, Shimoni U.

    2016-01-01

    Lack of diet diversity causing micronutrient deficiency is common in developing countries and is gaining attention due to the hidden consequences of impaired physical and cognitive development. This paper describes the propagation of a sustainable perennial kitchen garden (KG) model to address household (HH) diet diversity in Melghat. Nutrient dense plants, comprising of minimum one tree (perennial) and one green leafy vegetable (GLV) were given to participating HHs along with qualitative interventions. Baseline survey was conducted in winter 2011 followed by seasonal surveys over 2 years to record changes in KG practices, dietary intake and childcare practices. Marked increase from 4% at baseline to 95% at endline was seen in the KG maintainance. Increased diversity was seen in all food categories other than cereals and pulses. Variety of GLVs consumed increased over the two winters as well as the 2 summers. However, no change in the quantity of GLV consumed was noted which was attributed to the duration of the study period being insufficient for the trees to grow and provide adequate leaves for consumption. Notably, livelihood component was not promoted and HHs were encouraged to harvest and distribute excess seeds to relatives and neighbours. The study generated huge demand from HHs within the intervention and neighbouring villages. It concludes that a well designed perennial KG along with imparting adequate knowledge can be a sustainable practice to increase diet diversity and GLV intake which would help address micronutrient deficiencies in the community. PMID:26573040

  19. Characterization of Seasonally Dependent Emergent Vegetation Variables for Coastal Impact Models

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

    Emergent wetland vegetation has been shown to mitigate coastal inundation and erosion hazards by reducing wave energy through friction (Shepard et al., 2011), although its use in coastal protection planning is limited because predictive models require improved vegetation data. We isolated biophysical characteristics (biomass, stem density, rigidity, etc.) of plants using horizontal digital photographs (Side-On Photos) in conjunction with remote sensing and physical surveys. We studied the dominant salt-marsh species/assemblages in Port Susan Bay of Washington State, a vulnerable estuary that has experienced up to 1 kilometer of marsh retreat since the mid-1960s. We measured plant height, stem diameter, stem density (area available for flow) from fall to early spring (August 2014 through April 2015) using Side-On Photography and digital image processing techniques. Metrics from Side-On Photography were highly correlated to physical lab measurements. Vegetation rigidity was measured in-situ with a handheld digital scale with respect to measurement height and bending angle. Plant elasticity showed a strong correlation to stem diameter in two dominant bulrush species. We employed remote sensing supervised classifications techniques (Maximum-Likelihood and Decision Tree Classifiers) to hyperspectral imagery to map the spatial extent of vegetation assemblages with an overall accuracy of 86.7%. Combining these methods enabled us to extrapolate and validate vegetation characteristics across the study area and to estimate species-specific friction coefficients for input to cross-shore wave models. On-going studies include sensitivity analyses of wave models to seasonally-dependent vegetation parameters in the nearshore and ultimately wave impacts along the coast. By accounting for site-specific and spatiotemporal variability in vegetation data, we inform scientific understanding of the interactions of vegetation, waves, and sediment processes.

  20. Climate change and Ecotone boundaries: Insights from a cellular automata ecohydrology model in a Mediterranean catchment with topography controlled vegetation patterns

    NASA Astrophysics Data System (ADS)

    Caracciolo, Domenico; Noto, Leonardo Valerio; Istanbulluoglu, Erkan; Fatichi, Simone; Zhou, Xiaochi

    2014-11-01

    Regions of vegetation transitions (ecotones) are known to be highly sensitive to climate fluctuations. In this study, the Cellular-Automata Tree Grass Shrub Simulator (CATGraSS) has been modified, calibrated and used with downscaled future climate scenarios to examine the role of climate change on vegetation patterns in a steep mountainous catchment (1.3 km2) located in Sicily, Italy. In the catchment, north-facing slopes are mostly covered by trees and grass, and south-facing slopes by Indian Fig opuntia and grass, with grasses dominating as elevation grows. CATGraSS simulates solar radiation, evapotranspiration, and soil moisture in space and time. Each model cell can hold a single plant type or can be bare soil. Plant competition is modeled explicitly through mortality and the establishment of individual plants in open spaces. In this study, CATGraSS is modified to account for heterogeneity in soil thickness and tested in the study catchment using the historical climate of the region. Predicted vegetation patterns are compared with those obtained from satellite images. Results of model under current climate underscore the importance of solar irradiance and soil thickness, especially in the uplands where soil is shallow, in determining vegetation composition over complex terrain. A stochastic weather generator is used to generate future climate change scenarios for the catchment by downscaling GCM realizations in space and time. Future increase in atmospheric CO2 concentration was considered through modifying the vegetation water use efficiency and stomatal resistance for our study site. Model results suggest that vegetation pattern is highly sensitive to temperature and rainfall variations provided by climate scenarios (30% reduction of the annual precipitation and a 2.8 °C increase of the mean annual temperature). Future climate change is predicted to bring a considerable reorganization of the plant composition following topographic patterns, leading to a

  1. Diversity and Community: The Role of Agent-Based Modeling.

    PubMed

    Stivala, Alex

    2017-03-13

    Community psychology involves several dialectics between potentially opposing ideals, such as theory and practice, rights and needs, and respect for human diversity and sense of community. Some recent papers in the American Journal of Community Psychology have examined the diversity-community dialectic, some with the aid of agent-based modeling and concepts from network science. This paper further elucidates these concepts and suggests that research in community psychology can benefit from a useful dialectic between agent-based modeling and the real-world concerns of community psychology.

  2. PALADYN, a comprehensive land surface-vegetation-carbon cycle model of intermediate complexity

    NASA Astrophysics Data System (ADS)

    Willeit, Matteo; Ganopolski, Andrey

    2016-04-01

    PALADYN is presented, a new comprehensive and computationally efficient land surface-vegetation-carbon cycle model designed to be used in Earth system models of intermediate complexity for long-term simulations and paleoclimate studies. The model treats in a consistent manner the interaction between atmosphere, terrestrial vegetation and soil through the fluxes of energy, water and carbon. Energy, water and carbon are conserved. The model explicitly treats permafrost, both in physical processes and as important carbon pool. The model distinguishes 9 surface types of which 5 are different vegetation types, bare soil, land ice, lake and ocean shelf. Including the ocean shelf allows to treat continuous changes in sea level and shelf area associated with glacial cycles. Over each surface type the model solves the surface energy balance and computes the fluxes of sensible, latent and ground heat and upward shortwave and longwave radiation. It includes a single snow layer. The soil model distinguishes between three different macro surface types which have their own soil column: vegetation and bare soil, ice sheet and ocean shelf. The soil is vertically discretized into 5 layers where prognostic equations for temperature, water and carbon are consistently solved. Phase changes of water in the soil are explicitly considered. A surface hydrology module computes precipitation interception by vegetation, surface runoff and soil infiltration. The soil water equation is based on Darcy's law. Given soil water content, the wetland fraction is computed based on a topographic index. Photosynthesis is computed using a light use efficiency model. Carbon assimilation by vegetation is coupled to the transpiration of water through stomatal conductance. The model includes a dynamic vegetation module with 5 plant functional types competing for the gridcell share with their respective net primary productivity. Each macro surface type has its own carbon pools represented by a litter, a fast

  3. Combining geostatistical models and remotely sensed data to improve vegetation classification in Horqin sandy land

    NASA Astrophysics Data System (ADS)

    Liao, Chujiang

    2015-08-01

    On different degrees of desertification land, there exists different vegetation communities, and spatial structure differences are obvious among different vegetation communities. This study implemented variogram calculation using typical sample selected from the image, adopting a common global optimization method to fit them into the spherical model. The results showed that the difference is obvious among different vegetation communities for the sill and range, such as, the sill and range are smaller for sample variogram of Artemisia halodendron and Salix flavida community than that of Artemisia halodendron and Caragana microphylla community, and the range for sample variogram of Agriophyllum arenarium community is bigger than that of Artemisia halodendron and Salix flavida community, but smaller than that of Artemisia halodendron and Caragana microphylla community. Incorporating the difference of the spatial structure characterization into the vegetation classification can improve sample separation, thereby increasing the overall classification accuracy.

  4. Modeling the effects of vegetation on methane oxidation and emissions through soil landfill final covers across different climates.

    PubMed

    Abichou, Tarek; Kormi, Tarek; Yuan, Lei; Johnson, Terry; Francisco, Escobar

    2015-02-01

    Plant roots are reported to enhance the aeration of soil by creating secondary macropores which improve the diffusion of oxygen into soil as well as the supply of methane to bacteria. Therefore, methane oxidation can be improved considerably by the soil structuring processes of vegetation, along with the increase of organic biomass in the soil associated with plant roots. This study consisted of using a numerical model that combines flow of water and heat with gas transport and oxidation in soils, to simulate methane emission and oxidation through simulated vegetated and non-vegetated landfill covers under different climatic conditions. Different simulations were performed using different methane loading flux (5-200 g m(-2) d(-1)) as the bottom boundary. The lowest modeled surface emissions were always obtained with vegetated soil covers for all simulated climates. The largest differences in simulated surface emissions between the vegetated and non-vegetated scenarios occur during the growing season. Higher average yearly percent oxidation was obtained in simulations with vegetated soil covers as compared to non-vegetated scenario. The modeled effects of vegetation on methane surface emissions and percent oxidation were attributed to two separate mechanisms: (1) increase in methane oxidation associated with the change of the physical properties of the upper vegetative layer and (2) increase in organic matter associated with vegetated soil layers. Finally, correlations between percent oxidation and methane loading into simulated vegetated and non-vegetated covers were proposed to allow decision makers to compare vegetated versus non-vegetated soil landfill covers. These results were obtained using a modeling study with several simplifying assumptions that do not capture the complexities of vegetated soils under field conditions.

  5. Modelling vegetation dynamics at global scale due to climate changes: Comparison of two approaches

    SciTech Connect

    Belotelov, N.V.; Bogatyrev, B.G.; Lobanov, A.I.

    1996-12-31

    Climate changes will influence vegetation dynamics. One of the ways of forecasting these changes is the creation of mathematical models describing vegetation dynamics. Computer experiments can then be conducted under climate change scenarios. Two main approaches are used to create such models. The first approach is based on a bioclimatic dynamic approach. The second approach is based on modelling the main eco-physiological processes. The bioclimatic dynamic approach consists of hypotheses about vegetation types or biomes, and their interrelationships with climate. In the eco-physiological approach, a detailed description of the processes, such as production, mortality, plants migration and their competition is presented. A number of computer experiments has been conducted for several climatic scenario for Russia and the whole world. A qualitative comparison of the results with the results of an earlier bioclimatic model has been done.

  6. A model of the coupled dynamics of climate, vegetation and terrestrial ecosystem biogeochemistry for regional applications

    NASA Astrophysics Data System (ADS)

    Smith, Benjamin; Samuelsson, Patrick; Wramneby, Anna; Rummukainen, Markku

    2011-01-01

    Regional climate models (RCMs) primarily represent physical components of the climate system, omitting vegetation dynamics, ecosystem biogeochemistry and their associated feedbacks. To account for such feedbacks, we implemented a novel plant individual-based vegetation dynamics-ecosystem biogeochemistry scheme within the RCA3 RCM. Variations in leaf area index (LAI) of seven plant functional type (PFTs) in response to physical forcing and evolving vegetation state feed back to climate via adjustments in surface energy fluxes and surface properties. In an ERA-40-driven simulation over Europe, the model reproduces the recent past climate with comparable accuracy to the standard RCM. Large-scale patterns of LAI, net primary production and vegetation composition were comparable with observations, although winter LAI was systematically overestimated compared to satellite estimates. Analysis of the ERA-40 simulation and an A1B climate-change simulation revealed considerable covariation among dynamic variables of the physical climate and vegetation. At a Mediterranean site, periodic soil water limitation led to fluctuations in leaf cover and a likely positive feedback to near-surface temperature. At an alpine site, rising temperatures led to forest advance onto tundra areas, reducing albedo and effecting a likely positive feedback on temperature. Climate-vegetation coupling was less pronounced but still apparent at intermediate temperate and boreal sites.

  7. A global vegetation corrected SRTM DEM for use in hazard modelling

    NASA Astrophysics Data System (ADS)

    Bates, P. D.; O'Loughlin, F.; Neal, J. C.; Durand, M. T.; Alsdorf, D. E.; Paiva, R. C. D.

    2015-12-01

    We present the methodology and results from the development of a near-global 'bare-earth' Digital Elevation Model (DEM) derived from the Shuttle Radar Topography Mission (SRTM) data. Digital Elevation Models are the most important input for hazard modelling, as the DEM quality governs the accuracy of the model outputs. While SRTM is currently the best near-globally [60N to 60S] available DEM, it requires adjustments to reduce the vegetation contamination and make it useful for hazard modelling over heavily vegetated areas (e.g. tropical wetlands). Unlike previous methods of accounting for vegetation contamination, which concentrated on correcting relatively small areas and usually applied a static adjustment, we account for vegetation contamination globally and apply a spatial varying correction, based on information about canopy height and density. Our new 'Bare-Earth' SRTM DEM combines multiple remote sensing datasets, including ICESat GLA14 ground elevations, the vegetation continuous field dataset as a proxy for penetration depth of SRTM and a global vegetation height map, to remove the vegetation artefacts present in the original SRTM DEM. In creating the final 'bare-earth' SRTM DEM dataset, we produced three different 'bare-earth' SRTM products. The first applies global parameters, while the second and third products apply parameters that are regionalised based on either climatic zones or vegetation types, respectively. We also tested two different canopy density proxies of different spatial resolution. Using ground elevations obtained from the ICESat GLA14 satellite altimeter, we calculate the residual errors for the raw SRTM and the three 'bare-earth' SRTM products and compare performances. The three 'bare-earth' products all show large improvements over the raw SRTM in vegetated areas with the overall mean bias reduced by between 75 and 92% from 4.94 m to 0.40 m. The overall standard deviation is reduced by between 29 and 33 % from 7.12 m to 4.80 m. As

  8. Data-based modelling and environmental sensitivity of vegetation in China

    NASA Astrophysics Data System (ADS)

    Wang, H.; Prentice, I. C.; Ni, J.

    2013-09-01

    A process-oriented niche specification (PONS) model was constructed to quantify climatic controls on the distribution of ecosystems, based on the vegetation map of China. PONS uses general hypotheses about bioclimatic controls to provide a "bridge" between statistical niche models and more complex process-based models. Canonical correspondence analysis provided an overview of relationships between the abundances of 55 plant communities in 0.1° grid cells and associated mean values of 20 predictor variables. Of these, GDD0 (accumulated degree days above 0 °C), Cramer-Prentice α (an estimate of the ratio of actual to equilibrium evapotranspiration) and mGDD5 (mean temperature during the period above 5 °C) showed the greatest predictive power. These three variables were used to develop generalized linear models for the probability of occurrence of 16 vegetation classes, aggregated from the original 55 types by k-means clustering according to bioclimatic similarity. Each class was hypothesized to possess a unimodal relationship to each bioclimate variable, independently of the other variables. A simple calibration was used to generate vegetation maps from the predicted probabilities of the classes. Modelled and observed vegetation maps showed good to excellent agreement (κ = 0.745). A sensitivity study examined modelled responses of vegetation distribution to spatially uniform changes in temperature, precipitation and [CO2], the latter included via an offset to α (based on an independent, data-based light use efficiency model for forest net primary production). Warming shifted the boundaries of most vegetation classes northward and westward while temperate steppe and desert replaced alpine tundra and steppe in the southeast of the Tibetan Plateau. Increased precipitation expanded mesic vegetation at the expense of xeric vegetation. The effect of [CO2] doubling was roughly equivalent to increasing precipitation by ~ 30%, favouring woody vegetation types

  9. Data-based modelling and environmental sensitivity of vegetation in China

    NASA Astrophysics Data System (ADS)

    Wang, H.; Prentice, I. C.; Ni, J.

    2013-01-01

    A process-oriented niche specification (PONS) model was constructed to quantify climatic controls on the distribution of ecosystems, based on the vegetation map of China. PONS uses general hypotheses about bioclimatic controls to provide a "bridge" between statistical niche models and more complex process-based models. Canonical correspondence analysis provided an overview of relationships between the abundances of 55 plant communities in 0.1° grid cells and associated mean values of 20 predictor variables. Of these, GDD (accumulated degree days above 0 °C) Cramer-Prentice α (an estimate of the ratio of actual to equilibrium evapotranspiration) and mGDD5 (mean temperature during the period above 5 °C) showed the greatest predictive power. These three variables were used to develop generalized linear models for the probability of occurrence of 16 vegetation classes, aggregated from the original 55 types by k-means clustering according to bioclimatic similarity. Each class was hypothesized to possess a unimodal relationship to each bioclimate variable, independently of the other variables. A simple calibration was used to generate vegetation maps from the predicted probabilities of the classes. Modelled and observed vegetation maps showed good to excellent agreement (κ = 0.745). A sensitivity study examined modelled responses of vegetation distribution to spatially uniform changes in temperature, precipitation and [CO2], the latter included via an offset to α (based on an independent, data-based light use efficiency model for forest net primary production). Warming shifted the boundaries of most vegetation classes northward and westward while temperate steppe and desert replaced alpine tundra and steppe in the southeast of the Tibetan Plateau. Increased precipitation expanded mesic vegetation at the expense of xeric vegetation. The effect of [CO2] doubling was roughly equivalent to increasing precipitation by ∼ 30%, favouring woody vegetation types

  10. Influence of vegetation dynamic modeling on the allocation of green and blue waters

    NASA Astrophysics Data System (ADS)

    Ruiz-Pérez, Guiomar; Francés, Félix

    2015-04-01

    The long history of the Mediterranean region is dominated by the interactions and co-evolution between man and its natural environment. It is important to consider that the Mediterranean region is recurrently or permanently confronted with the scarcity of the water. The issue of climate change is (and will be) aggravating this situation. This raises the question of a loss of services that ecosystems provide to human and also the amount of available water to be used by vegetation. The question of the water cycle, therefore, should be considered in an integrated manner by taking into account both blue water (water in liquid form used for the human needs or which flows into the oceans) and green water (water having the vapor for resulting from evaporation and transpiration processes). In spite of this, traditionally, very few hydrological models have incorporated the vegetation dynamic as a state variable. In fact, most of them are able to represent fairly well the observed discharge, but usually including the vegetation as a static parameter. However, in the last decade, the number of hydrological models which explicitly take into account the vegetation development as a state variable has increased substantially. In this work, we want to analyze if it is really necessary to use a dynamic vegetation model to quantify adequately the distribution of water into blue and green water. The study site is located in the Public Forest Monte de la Hunde y Palomeras (Spain). The vegetation in the study area is dominated by Aleppo pine of high tree density with scant presence of other species. Two different daily models were applied (with static and dynamic vegetation representation respectively) in three different scenarios: dry year (2005), normal year (2008) and wet year (2010). The static vegetation model simulates the evapotranspiration considering the vegetation as a stationary parameter. Contrarily, the dynamic vegetation model connects the hydrological model with a

  11. Projected vegetation changes for the American Southwest: combined dynamic modeling and bioclimatic-envelope approach.

    PubMed

    Notaro, Michael; Mauss, Adrien; Williams, John W

    2012-06-01

    This study focuses on potential impacts of 21st century climate change on vegetation in the Southwest United States, based on debiased and interpolated climate projections from 17 global climate models used in the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Among these models a warming trend is universal, but projected changes in precipitation vary in sign and magnitude. Two independent methods are applied: a dynamic global vegetation model to assess changes in plant functional types and bioclimatic envelope modeling to assess changes in individual tree and shrub species and biodiversity. The former approach investigates broad responses of plant functional types to climate change, while considering competition, disturbances, and carbon fertilization, while the latter approach focuses on the response of individual plant species, and net biodiversity, to climate change. The dynamic model simulates a region-wide reduction in vegetation cover during the 21st century, with a partial replacement of evergreen trees with grasses in the mountains of Colorado and Utah, except at the highest elevations, where tree cover increases. Across southern Arizona, central New Mexico, and eastern Colorado, grass cover declines, in some cases abruptly. Due to the prevalent warming trend among all 17 climate models, vegetation cover declines in the 21st century, with the greatest vegetation losses associated with models that project a drying trend. The inclusion of the carbon fertilization effect largely ameliorates the projected vegetation loss. Based on bioclimatic envelope modeling for the 21st century, the number of tree and shrub species that are expected to experience robust declines in range likely outweighs the number of species that are expected to expand in range. Dramatic shifts in plant species richness are projected, with declines in the high-elevation evergreen forests, increases in the eastern New Mexico prairies, and a northward shift of the

  12. The interplay between cooperativity and diversity in model threshold ensembles.

    PubMed

    Cervera, Javier; Manzanares, José A; Mafe, Salvador

    2014-10-06

    The interplay between cooperativity and diversity is crucial for biological ensembles because single molecule experiments show a significant degree of heterogeneity and also for artificial nanostructures because of the high individual variability characteristic of nanoscale units. We study the cross-effects between cooperativity and diversity in model threshold ensembles composed of individually different units that show a cooperative behaviour. The units are modelled as statistical distributions of parameters (the individual threshold potentials here) characterized by central and width distribution values. The simulations show that the interplay between cooperativity and diversity results in ensemble-averaged responses of interest for the understanding of electrical transduction in cell membranes, the experimental characterization of heterogeneous groups of biomolecules and the development of biologically inspired engineering designs with individually different building blocks. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

  13. The interplay between cooperativity and diversity in model threshold ensembles

    PubMed Central

    Cervera, Javier; Manzanares, José A.; Mafe, Salvador

    2014-01-01

    The interplay between cooperativity and diversity is crucial for biological ensembles because single molecule experiments show a significant degree of heterogeneity and also for artificial nanostructures because of the high individual variability characteristic of nanoscale units. We study the cross-effects between cooperativity and diversity in model threshold ensembles composed of individually different units that show a cooperative behaviour. The units are modelled as statistical distributions of parameters (the individual threshold potentials here) characterized by central and width distribution values. The simulations show that the interplay between cooperativity and diversity results in ensemble-averaged responses of interest for the understanding of electrical transduction in cell membranes, the experimental characterization of heterogeneous groups of biomolecules and the development of biologically inspired engineering designs with individually different building blocks. PMID:25142516

  14. Modelling spatial and temporal vegetation variability with the Climate Constrained Vegetation Index: evidence of CO2 fertilisation and of water stress in continental interiors

    NASA Astrophysics Data System (ADS)

    Los, S. O.

    2015-06-01

    A model was developed to simulate spatial, seasonal and interannual variations in vegetation in response to temperature, precipitation and atmospheric CO2 concentrations; the model addresses shortcomings in current implementations. The model uses the minimum of 12 temperature and precipitation constraint functions to simulate NDVI. Functions vary based on the Köppen-Trewartha climate classification to take adaptations of vegetation to climate into account. The simulated NDVI, referred to as the climate constrained vegetation index (CCVI), captured the spatial variability (0.82 < r <0.87), seasonal variability (median r = 0.83) and interannual variability (median global r = 0.24) in NDVI. The CCVI simulated the effects of adverse climate on vegetation during the 1984 drought in the Sahel and during dust bowls of the 1930s and 1950s in the Great Plains in North America. A global CO2 fertilisation effect was found in NDVI data, similar in magnitude to that of earlier estimates (8 % for the 20th century). This effect increased linearly with simple ratio, a transformation of the NDVI. Three CCVI scenarios, based on climate simulations using the representative concentration pathway RCP4.5, showed a greater sensitivity of vegetation towards precipitation in Northern Hemisphere mid latitudes than is currently implemented in climate models. This higher sensitivity is of importance to assess the impact of climate variability on vegetation, in particular on agricultural productivity.

  15. Diversity and Impacts of Mining on the Non-Volant Small Mammal Communities of Two Vegetation Types in the Brazilian Amazon.

    PubMed

    Ardente, Natália Carneiro; Ferreguetti, Átilla Colombo; Gettinger, Donald; Leal, Pricila; Mendes-Oliveira, Ana Cristina; Martins-Hatano, Fernanda; Bergallo, Helena Godoy

    2016-01-01

    The Carajás National Forest contains some of the largest iron ore deposits in the world. The majority of the minerals are found below a plant community known as Savana Metalófila, or "Canga", which represents only 3% of the landscape within the Carajás National Forest (CNF). The aim of our study was to understand the diversity of community of non-volant small mammals in the two predominant vegetation types: Ombrophilous Forest and Canga, and to examine how mining impacts these communities. Sampling was conducted from January 2010 to August 2011 in 11 sampling sites divided by the total area of Canga and 12 sampling sites in the forest, totalizing 23 sites. Of these, 12 sites (Canga and Forest) were considered impacted areas located close to the mine (< 900 meters) and 11 sites (Canga and Forest), serving as controls, which were at least 7,000 meters from the mine. We recorded 28 species, 11 from the Order Didelphimorphia and 17 from the Order Rodentia. The two forest types shared 68.42% of the species found in the CNF. A gradient analysis (Non-metric multidimensional scaling) revealed that the first axis clearly separated the non-flying small mammal communities by vegetation type. Occupancy models showed that the detectability of species was affected by the distance from the mining activities. Of all the small mammals analyzed, 10 species were positively affected by the distance from mining in areas impacted (e.g. more likely to be detected farther from mining areas) and detectability was lower in impacted areas. However, three species were negatively affected by the distance from mining, with higher detectability in the impacted areas, and seven species showed no effect of their proximity to mining operations. To date, there are no studies in Brazil about the impact of mining on mammals or other vertebrates. This study reveals that the effect of mining may go beyond the forest destruction caused by the opening of the mining pits, but also may negatively affect

  16. Diversity and Impacts of Mining on the Non-Volant Small Mammal Communities of Two Vegetation Types in the Brazilian Amazon

    PubMed Central

    Ardente, Natália Carneiro; Ferreguetti, Átilla Colombo; Gettinger, Donald; Leal, Pricila; Mendes-Oliveira, Ana Cristina; Martins-Hatano, Fernanda; Bergallo, Helena Godoy

    2016-01-01

    The Carajás National Forest contains some of the largest iron ore deposits in the world. The majority of the minerals are found below a plant community known as Savana Metalófila, or “Canga”, which represents only 3% of the landscape within the Carajás National Forest (CNF). The aim of our study was to understand the diversity of community of non-volant small mammals in the two predominant vegetation types: Ombrophilous Forest and Canga, and to examine how mining impacts these communities. Sampling was conducted from January 2010 to August 2011 in 11 sampling sites divided by the total area of Canga and 12 sampling sites in the forest, totalizing 23 sites. Of these, 12 sites (Canga and Forest) were considered impacted areas located close to the mine (<< 900 meters) and 11 sites (Canga and Forest), serving as controls, which were at least 7,000 meters from the mine. We recorded 28 species, 11 from the Order Didelphimorphia and 17 from the Order Rodentia. The two forest types shared 68.42% of the species found in the CNF. A gradient analysis (Non-metric multidimensional scaling) revealed that the first axis clearly separated the non-flying small mammal communities by vegetation type. Occupancy models showed that the detectability of species was affected by the distance from the mining activities. Of all the small mammals analyzed, 10 species were positively affected by the distance from mining in areas impacted (e.g. more likely to be detected farther from mining areas) and detectability was lower in impacted areas. However, three species were negatively affected by the distance from mining, with higher detectability in the impacted areas, and seven species showed no effect of their proximity to mining operations. To date, there are no studies in Brazil about the impact of mining on mammals or other vertebrates. This study reveals that the effect of mining may go beyond the forest destruction caused by the opening of the mining pits, but also may negatively

  17. Understory vegetation

    Treesearch

    Steve Sutherland; Todd F. Hutchinson; Jennifer L. Windus

    2003-01-01

    This chapter documents patterns of species composition and diversity within the understory vegetation layer and provides a species list for the four study areas in southern Ohio. Within each of 108 plots, we recorded the frequency of all vascular plant species in sixteen 2-m² quadrats. We recorded 297 species, including 187 forbs (176 perennials, 9 annuals, 2...

  18. A new vegetation model at the topographic scale in Mongolia under human activity and climate change

    NASA Astrophysics Data System (ADS)

    Ishii, R.; Matsuoka, M.; Fujita, N.

    2013-12-01

    To predict future vegetation not only the changes in climate conditions but those of essential human activities must also be incorporated in a vegetation model, since most terrestrial systems are now under the strong influence of both of these drivers. Previous dynamic vegetation models, however, had difficulties to incorporate these effects in a comparative way and one of the critical barrier was the mismatch of the spatial scales at which both of these drivers are quantified, that is, climate conditions are generally observed and modeled with much coarser resolutions than human activities often influenced by topography or transportation networks. In northern part of Mongolia, where plant growth is basically limited by water availability and grazing pressure by livestock, the vegetation exhibits a clear discontinuous transition between grassland and forest but no sound modeling could be achieved to clarify the transition mechanisms nor to project future vegetation and hence the distribution of ecosystem functions. To tackle this problem, we developed a pair of new models at the topographic scale (Models 1&2) based on the observation in a sample region in Mongolia. Model 1 is a mathematical model for the dynamic interactions among the two plant biomasses (grass and trees) and local soil water content (SWC). We here assume positive/negative feedbacks in plant growth-SWC interaction and uneven grazing pressures for the two plants. Model 2 estimates numerically the spatial distribution of the potential SWC governed by climate and topography conditions in a given region. We used satellite remote sensing data to obtain the spatial distributions of the initial vegetation cover and the topography. By integrating these two models we could successfully reconstruct the current spatial vegetation patterns in our sample area only when we assumed a strong positive feedback in plant growth-SWC interaction and grazing pressure. This result underscores the importance of the

  19. Fire emissions simulated by prescribing burned area observations in a global vegetation model

    NASA Astrophysics Data System (ADS)

    Khlystova, Iryna G.; Wilkenskjeld, Stiig; Kloster, Silvia

    2014-05-01

    The emissions of trace gases and aerosols from large vegetation fires into the atmosphere have an important climate impact. In this study we integrate observed burned area into a global vegetation model to derive global fire emissions. A global continuous burned area products provided by GFED (Global Fire Emissions Dataset) were obtained from MODIS (and pre-MODIS) satellites and are available for the time period 1997-2011. We integrate the global burned area product into the global vegetation model JSBACH, a land part of the Earth-System model developed at the Max Planck Institute for Meteorology. JSBACH simulates land biomass in terms of carbon, which can be combined with the satellite burned area information to derive fire carbon emissions. Some assumptions on fire fuel consumptions have to be made during the integration of satellite burned area into the JSBACH. This includes processes such as tree mortality and combustion completeness, i.e. how much of the vegetation biomass gets combusted during a fire. Partially, this information can be also obtained from measurements. In this study we follow closely the approach of GFED, incorporating also GFED supplemental information, to simulate fuel consumption in JSBACH. And we compare simulated by this approach fire carbon emissions with the fire emissions from GFED. Global vegetation models often use prescribed land cover maps. The simulated in the JSBACH vegetation biomass and thus the simulated fire carbon emissions critically depend on the land cover distribution. In our study we derive fire carbon emissions using two different land cover parameterizations, based on two different satellite datasets. We will present the results obtained from simulations using the JSBACH standard MODIS based vegetation distribution and compare them to the results derived using the recently released ESA CCI land cover satellite product to demonstrate the sensitivity of simulated fire carbon emissions to the underlying land cover

  20. Modeling Vegetation Dynamics in Response to Hydrological Changes in a Small Urban Tropical Freshwater Wetland

    NASA Astrophysics Data System (ADS)

    Chui, T. M.; Palanisamy, B.; Mohanadas, H.

    2011-12-01

    Wetlands worldwide face drastic degradation from human-induced changes. A small freshwater wetland located within the dense urbanized island state of Singapore---the Nee Soon Wetland---is no exception. It is the only significant locality in Singapore of peat swamp forest and is home to a wide range of rare and endangered floral and faunal species. Unfortunately, changes in downstream land use and surrounding reservoirs' operations may pose threats to the coupled hydrological and vegetation systems. This study develops and applies coupled hydrological-vegetation models to understand the dynamic relationships between hydrology and vegetation systems, and simulates vegetation responses to hydrological changes in Nee Soon. The models combine a hydrological component with a vegetation component. The hydrological component accounts for both saturated and unsaturated flows, and incorporates evapotranspiration, rainfall infiltration and recharge from streams and reservoirs. The vegetation component is described by Lokta-Volterra equations that are tailored for plant growth, to simulate the vegetation dynamics of up to three species that thrive in different flooding conditions. Important findings include: (1) groundwater levels within Nee Soon are not highly sensitive to the operating levels of the surrounding reservoirs. However, (2) downstream drainage results in a localized zone of influence with significant adverse impacts, especially on the less flood-tolerant species. In addition, (3) the severely impacted less flood-tolerant species is unable to recover even when previous hydrological conditions are restored, unless the downstream drainage duration is reduced, or the plant characteristics such as maximum assimilation rates or competitiveness are increased. Finally, (4) hydrological conditions and species competitiveness supersede any other plant growth characteristics in determining the stable coexistence of different species. The developed models and modeling

  1. Vegetation-rainfall feedbacks across the Sahel: a combined observational and modeling study

    NASA Astrophysics Data System (ADS)

    Yu, Y.; Notaro, M.; Wang, F.; Mao, J.; Shi, X.; Wei, Y.

    2016-12-01

    The Sahel rainfall is characterized by large interannual variability. Past modeling studies have concluded that the Sahel rainfall variability is primarily driven by oceanic forcings and amplified by land-atmosphere interactions. However, the relative importance of oceanic versus terrestrial drivers has never been assessed from observations. The current understanding of vegetation's impacts on climate, i.e. positive vegetation-rainfall feedback through the albedo, moisture, and momentum mechanisms, comes from untested models. Neither the positive vegetation-rainfall feedback, nor the underlying mechanisms, has been fully resolved in observations. The current study fills the knowledge gap about the observed vegetation-rainfall feedbacks, through the application of the multivariate statistical method Generalized Equilibrium Feedback Assessment (GEFA) to observational data. According to GEFA, the observed oceanic impacts dominate over terrestrial impacts on Sahel rainfall, except in the post-monsoon period. Positive leaf area index (LAI) anomalies favor an extended, wetter monsoon across the Sahel, largely due to moisture recycling. The albedo mechanism is not responsible for this positive vegetation feedback on the seasonal-interannual time scale, which is too short for a grass-desert transition. A low-level stabilization and subsidence is observed in response to increased LAI - potentially responsible for a negative vegetation-rainfall feedback. However, the positive moisture feedback overwhelms the negative momentum feedback, resulting in an observed positive vegetation-rainfall feedback. We further applied GEFA to a fully-coupled Community Earth System Model (CESM) control run, as an example of evaluating climate models against the GEFA-based observational benchmark. In contrast to the observed positive vegetation-rainfall feedbacks, CESM simulates a negative vegetation-rainfall feedback across Sahel, peaking in the pre-monsoon season. The simulated negative

  2. Predicting the impact of water demand and river flow regulation over riparian vegetation through mathematical modeling

    NASA Astrophysics Data System (ADS)

    Garcia-Arias, A.; Pons, C.; Frances, F.

    2013-12-01

    The vegetation of the riversides is a main part of the complex riparian ecosystems and has an important role maintaining the fluvial ecosystems. Biotic and abiotic interactions between the river and the riverbank are essential for the subsistence and the development of both ecosystems. In semi-arid Mediterranean areas, the riparian vegetation growth and distribution is especially controlled by the water accessibility, determining the limit between the lush riparian bands and the sparse upland. Human intervention can alter the river hydrology determining the riparian vegetation wellbeing and its distribution and, in consequence, affecting both riparian and fluvial ecosystems. Predictive models are necessary decision support tools for adequate river management and restoration initiatives. In this context, the RibAV model is useful to predict the impact of water demand and river flow regulation on the riparian vegetation. RibAV is able to reproduce the vegetation performance on the riverside allowing the scenarios analysis in terms of vegetation distribution and wellbeing. In this research several flow regulation and water demand scenarios are proposed and the impacts over three plant functional types (PFTs) are analyzed. The PFTs group the herbaceous riparian plants, the woody riparian plants and the terrestrial vegetation. The study site is the Terde reach at the Mijares River, a 539m length reach located in a semi-arid Mediterranean area in Spain. The scenarios represent river flow alterations required to attend different human demands. These demands encompass different seasonality, magnitude and location. The seasonality is represented as hydroelectric (constant all over the year), urban (increased during the summer period) and agricultural demands (monthly seasonality). The magnitude is varied considering the 20%, the 40% and the 80% of the mean daily flow. Two locations are considered, upstream or downstream the study site. To attend the demands located

  3. Modeling mechanisms of vegetation change due to fire in a semi-arid ecosystem

    USGS Publications Warehouse

    White, J.D.; Gutzwiller, K.J.; Barrow, W.C.; Randall, L.J.; Swint, P.

    2008-01-01

    Vegetation growth and community composition in semi-arid environments is determined by water availability and carbon assimilation mechanisms specific to different plant types. Disturbance also impacts vegetation productivity and composition dependent on area affected, intensity, and frequency factors. In this study, a new spatially explicit ecosystem model is presented for the purpose of simulating vegetation cover type changes associated with fire disturbance in the northern Chihuahuan Desert region. The model is called the Landscape and Fire Simulator (LAFS) and represents physiological activity of six functional plant types incorporating site climate, fire, and seed dispersal routines for individual grid cells. We applied this model for Big Bend National Park, Texas, by assessing the impact of wildfire on the trajectory of vegetation communities over time. The model was initialized and calibrated based on landcover maps derived from Landsat-5 Thematic Mapper data acquired in 1986 and 1999 coupled with plant biomass measurements collected in the field during 2000. Initial vegetation cover change analysis from satellite data showed shrub encroachment during this time period that was captured in the simulated results. A synthetic 50-year climate record was derived from historical meteorological data to assess system response based on initial landcover conditions. This simulation showed that shrublands increased to the detriment of grass and yucca-ocotillo vegetation cover types indicating an ecosystem-level trajectory for shrub encroachment. Our analysis of simulated fires also showed that fires significantly reduced site biomass components including leaf area, stem, and seed biomass in this semi-arid ecosystem. In contrast to other landscape simulation models, this new model incorporates detailed physiological responses of functional plant types that will allow us to simulated the impact of increased atmospheric CO2 occurring with climate change coupled with fire

  4. Integrated modeling of long-term vegetation and hydrologic dynamics in Rocky Mountain watersheds

    Treesearch

    Robert Steven Ahl

    2007-01-01

    Changes in forest structure resulting from natural disturbances, or managed treatments, can have negative and long lasting impacts on water resources. To facilitate integrated management of forest and water resources, a System for Long-Term Integrated Management Modeling (SLIMM) was developed. By combining two spatially explicit, continuous time models, vegetation...

  5. Assessing forest vegetation and fire simulation model performance after the Cold Springs wildfire, Washington USA

    Treesearch

    Susan Hummel; Maureen Kennedy; E. Ashley. Steel

    2012-01-01

    Given that resource managers rely on computer simulation models when it is difficult or expensive to obtain vital information directly, it is important to evaluate how well a particular model satisfies applications for which it is designed. The Forest Vegetation Simulator (FVS) is used widely for forest management in the US, and its scope and complexity continue to...

  6. Models of vegetation change for landscape planning: a comparison of FETM, LANDSUM, SIMPPLLE, and VDDT

    Treesearch

    T. M. Barrett

    2001-01-01

    Landscape assessment and planning often depend on the ability to predict change of vegetation. This report compares four modeling systems (FETM, LANDSUM, SIMPPLLE, and VDDT) that can be used to understand changes resulting from succession, natural disturbance, and management activities. The four models may be useful for regional or local assessments in National Forest...

  7. A SIMPLE CELLULAR AUTOMATON MODEL FOR HIGH-LEVEL VEGETATION DYNAMICS

    EPA Science Inventory

    We have produced a simple two-dimensional (ground-plan) cellular automata model of vegetation dynamics specifically to investigate high-level community processes. The model is probabilistic, with individual plant behavior determined by physiologically-based rules derived from a w...

  8. A SIMPLE CELLULAR AUTOMATON MODEL FOR HIGH-LEVEL VEGETATION DYNAMICS

    EPA Science Inventory

    We have produced a simple two-dimensional (ground-plan) cellular automata model of vegetation dynamics specifically to investigate high-level community processes. The model is probabilistic, with individual plant behavior determined by physiologically-based rules derived from a w...

  9. Approaches to incorporating climate change effects in state and transition simulation models of vegetation

    Treesearch

    Becky K. Kerns; Miles A. Hemstrom; David Conklin; Gabriel I. Yospin; Bart Johnson; Dominique Bachelet; Scott Bridgham

    2012-01-01

    Understanding landscape vegetation dynamics often involves the use of scientifically-based modeling tools that are capable of testing alternative management scenarios given complex ecological, management, and social conditions. State-and-transition simulation model (STSM) frameworks and software such as PATH and VDDT are commonly used tools that simulate how landscapes...

  10. A predictive model for floating leaf vegetation in the St. Louis River Estuary

    EPA Science Inventory

    In July 2014, USEPA staff was asked by MPCA to develop a predictive model for floating leaf vegetation (FLV) in the St. Louis River Estuary (SLRE). The existing model (Host et al. 2012) greatly overpredicts FLV in St. Louis Bay probably because it was based on a limited number of...

  11. A predictive model for floating leaf vegetation in the St. Louis River Estuary

    EPA Science Inventory

    In July 2014, USEPA staff was asked by MPCA to develop a predictive model for floating leaf vegetation (FLV) in the St. Louis River Estuary (SLRE). The existing model (Host et al. 2012) greatly overpredicts FLV in St. Louis Bay probably because it was based on a limited number of...

  12. State-and-transition prototype model of riparian vegetation downstream of Glen Canyon Dam, Arizona

    USGS Publications Warehouse

    Ralston, Barbara E.; Starfield, Anthony M.; Black, Ronald S.; Van Lonkhuyzen, Robert A.

    2014-01-01

    Facing an altered riparian plant community dominated by nonnative species, resource managers are increasingly interested in understanding how to manage and promote healthy riparian habitats in which native species dominate. For regulated rivers, managing flows is one tool resource managers consider to achieve these goals. Among many factors that can influence riparian community composition, hydrology is a primary forcing variable. Frame-based models, used successfully in grassland systems, provide an opportunity for stakeholders concerned with riparian systems to evaluate potential riparian vegetation responses to alternative flows. Frame-based, state-and-transition models of riparian vegetation for reattachment bars, separation bars, and the channel margin found on the Colorado River downstream of Glen Canyon Dam were constructed using information from the literature. Frame-based models can be simple spreadsheet models (created in Microsoft® Excel) or developed further with programming languages (for example, C-sharp). The models described here include seven community states and five dam operations that cause transitions between states. Each model divides operations into growing (April–September) and non-growing seasons (October–March) and incorporates upper and lower bar models, using stage elevation as a division. The inputs (operations) can be used by stakeholders to evaluate flows that may promote dynamic riparian vegetation states, or identify those flow options that may promote less desirable states (for example, Tamarisk [Tamarix sp.] temporarily flooded shrubland). This prototype model, although simple, can still elicit discussion about operational options and vegetation response.

  13. An integrated model of soil, hydrology, and vegetation for carbon dynamics in wetland ecosystems

    Treesearch

    Yu Zhang; Changsheng Li; Carl C. Trettin; Harbin Li; Ge Sun

    2002-01-01

    Wetland ecosystems are an important component in global carbon (C) cycles and may exert a large influence on global clinlate change. Predictions of C dynamics require us to consider interactions among many critical factors of soil, hydrology, and vegetation. However, few such integrated C models exist for wetland ecosystems. In this paper, we report a simulation model...

  14. Detecting vegetation-precipitation feedbacks in mid-Holocene North Africa from two climate models

    SciTech Connect

    Wang, Yi; Notaro, Michael; Liu, Zhengyu; Gallimore, Robert; Levis, Samuel; Kutzbach, John E.

    2008-03-31

    Using two climate-vegetation model simulations from the Fast Ocean Atmosphere Model (FOAM) and the Community Climate System Model (CCSM, version 2), we investigate vegetation-precipitation feedbacks across North Africa during the mid-Holocene. From mid-Holocene snapshot runs of FOAM and CCSM2, we detect a negative feedback at the annual timescale with our statistical analysis. Using the Monte- Carlo bootstrap method, the annual negative feedback is further confirmed to be significant in both simulations. Additional analysis shows that this negative interaction is partially caused by the competition between evaporation and transpiration in North African grasslands. Furthermore, we find the feedbacks decrease with increasing timescales, and change signs from positive to negative at increasing timescales in FOAM. The proposed mechanism for this sign switch is associated with the different persistent timescales of upper and lower soil water contents, and their interactions with vegetation and atmospheric precipitation.

  15. Detecting vegetation-precipitation feedbacks in mid-Holocene North Africa from two climate models

    NASA Astrophysics Data System (ADS)

    Wang, Y.; Notaro, M.; Liu, Z.; Gallimore, R.; Levis, S.; Kutzbach, J. E.

    2007-07-01

    Using two climate-vegetation model simulations from the Fast Ocean Atmosphere Model (FOAM) and the Community Climate System Model (CCSM, version 2), we investigate vegetation-precipitation feedbacks across North Africa during the mid-Holocene. From mid-Holocene snapshot runs of FOAM and CCSM2, we detect a negative feedback at the annual timescale with our statistical analysis. Using the Monte-Carlo bootstrap method, the annual negative feedback is further confirmed to be significant in both simulations. Additional analysis shows that this negative interaction is partially caused by the competition between evaporation and transpiration in North African grasslands. Furthermore, we find the feedbacks decrease with increasing timescales, and change signs from positive to negative at increasing timescales in FOAM. The proposed mechanism for this sign switch is associated with the different persistent timescales of upper and lower soil water contents, and their interactions with vegetation and atmospheric precipitation.

  16. Detecting vegetation-precipitation feedbacks in mid-Holocene North Africa from two climate models

    NASA Astrophysics Data System (ADS)

    Wang, Y.; Notaro, M.; Liu, Z.; Gallimore, R.; Levis, S.; Kutzbach, J. E.

    2008-03-01

    Using two climate-vegetation model simulations from the Fast Ocean Atmosphere Model (FOAM) and the Community Climate System Model (CCSM, version 2), we investigate vegetation-precipitation feedbacks across North Africa during the mid-Holocene. From mid-Holocene snapshot runs of FOAM and CCSM2, we detect a negative feedback at the annual timescale with our statistical analysis. Using the Monte-Carlo bootstrap method, the annual negative feedback is further confirmed to be significant in both simulations. Additional analysis shows that this negative interaction is partially caused by the competition between evaporation and transpiration in North African grasslands. Furthermore, we find the feedbacks decrease with increasing timescales, and change signs from positive to negative at increasing timescales in FOAM. The proposed mechanism for this sign switch is associated with the different persistent timescales of upper and lower soil water contents, and their interactions with vegetation and atmospheric precipitation.

  17. Forest forming process and dynamic vegetation models under global change

    Treesearch

    A. Shvidenko; E. Gustafson

    2009-01-01

    The paper analyzes mathematical models that are used to project the dynamics of forest ecosystems on different spatial and temporal scales. Landscape disturbance and succession models (LDSMs) are of a particular interest for studying the forest forming process in Northern Eurasia. They have a solid empirical background and are able to model ecological processes under...

  18. Main vegetation types and plant species diversity along an altitudinal gradient of Al Baha region, Saudi Arabia.

    PubMed

    Al-Aklabi, Abdullah; Al-Khulaidi, Abdul Wali; Hussain, Akram; Al-Sagheer, Nageeb

    2016-11-01

    Plant species composition patterns and vegetation types were investigated along Elevational Gradients in Al Baha region, Saudi Arabia. Sandy plain, wadis, drainage lines, rocky outcrops, hills and fallow lands occur over a wide geographic range encompassing variation in plant species and communities among these different ecological sites. To provide a quantitatively based classification of the vegetation we used Multi Variant Statistical Package (MVSP) software, followed by the re-arrangement of a matrix of the similar plant species in rows and similar sample sites in columns. Plant density and environmental variables were measured and recorded in each quadrat. Two-way indicator species analysis and Canonical Correspondence Analysis (CCA) were used to analyze the relationships between vegetation and environmental variables, while Arc Map was used to analyze the pattern of plant species density. A total of 59 sample plots (25 × 25 m), stratified, randomly-placed relevés were collected in Al Baha region, along a cross section running from south-west to north-west. About 190 plant species belonging to 59 families were recognized. This study showed that these plant species formed 15 vegetation types that primarily correspond mainly to different combinations of elevation, and topography. The study concluded that this research has provided the first quantitative and systematic survey of the vegetation in Al Baha region.

  19. 6-n-propylthiouracil taster status not related to reported cruciferous vegetable intake among ethnically diverse children.

    PubMed

    Baranowski, Tom; Baranowski, Janice C; Watson, Kathleen B; Jago, Russell; Islam, Noemi; Beltran, Alicia; Martin, Shelby J; Nguyen, Nga; Tepper, Beverly J

    2011-08-01

    Sensitivity to the taste of 6-n-propylthiouracil (PROP) (a bitter chemical related to the phenylthiocarbamide found in cruciferous vegetables) has been related to dietary intake or preferences of cruciferous vegetables among adults and young children but not middle-aged children or adolescents. We hypothesized that PROP taste sensitivity is related to lower reported dietary intake of cruciferous vegetables, primarily among younger children (ie, a moderating effect of child age). This study examined the relationship of PROP sensitivity to reported dietary intake across 3 days in 2 age groups of youth (9-10 and 17-18 years) while statistically controlling for physical activity, social desirability, and reporting bias. Cross-sectional design was used with a multiethnic (white, African American, Hispanic, etc) sample of 843 men and women. Children were recruited from and data were collected in local elementary and high schools that had at least 30% ethnic minority enrollment. Children providing nonplausible reports of dietary intake were deleted from the analyses. Body mass index was calculated and expressed in z scores. Energy intake and physical activity were measured by 3 telephone-conducted 24-hour dietary recalls with the Nutrient Data System for Research and 5 days of Actigraph (ActiGraph, Shalimar, Florida) activity monitor. The primary analyses included 347 students. 6-n-Propylthiouracil sensitivity was not related to intake of cruciferous vegetables. Intakes of the cruciferous vegetables were low, which may explain the lack of relationship.

  20. A Forward GPS Multipath Simulator Based on the Vegetation Radiative Transfer Equation Model.

    PubMed

    Wu, Xuerui; Jin, Shuanggen; Xia, Junming

    2017-06-05

    Global Navigation Satellite Systems (GNSS) have been widely used in navigation, positioning and timing. Nowadays, the multipath errors may be re-utilized for the remote sensing of geophysical parameters (soil moisture, vegetation and snow depth), i.e., GPS-Multipath Reflectometry (GPS-MR). However, bistatic scattering properties and the relation between GPS observables and geophysical parameters are not clear, e.g., vegetation. In this paper, a new element on bistatic scattering properties of vegetation is incorporated into the traditional GPS-MR model. This new element is the first-order radiative transfer equation model. The new forward GPS multipath simulator is able to explicitly link the vegetation parameters with GPS multipath observables (signal-to-noise-ratio (SNR), code pseudorange and carrier phase observables). The trunk layer and its corresponding scattering mechanisms are ignored since GPS-MR is not suitable for high forest monitoring due to the coherence of direct and reflected signals. Based on this new model, the developed simulator can present how the GPS signals (L1 and L2 carrier frequencies, C/A, P(Y) and L2C modulations) are transmitted (scattered and absorbed) through vegetation medium and received by GPS receivers. Simulation results show that the wheat will decrease the amplitudes of GPS multipath observables (SNR, phase and code), if we increase the vegetation moisture contents or the scatters sizes (stem or leaf). Although the Specular-Ground component dominates the total specular scattering, vegetation covered ground soil moisture has almost no effects on the final multipath signatures. Our simulated results are consistent with previous results for environmental parameter detections by GPS-MR.

  1. A Forward GPS Multipath Simulator Based on the Vegetation Radiative Transfer Equation Model

    PubMed Central

    Wu, Xuerui; Jin, Shuanggen; Xia, Junming

    2017-01-01

    Global Navigation Satellite Systems (GNSS) have been widely used in navigation, positioning and timing. Nowadays, the multipath errors may be re-utilized for the remote sensing of geophysical parameters (soil moisture, vegetation and snow depth), i.e., GPS-Multipath Reflectometry (GPS-MR). However, bistatic scattering properties and the relation between GPS observables and geophysical parameters are not clear, e.g., vegetation. In this paper, a new element on bistatic scattering properties of vegetation is incorporated into the traditional GPS-MR model. This new element is the first-order radiative transfer equation model. The new forward GPS multipath simulator is able to explicitly link the vegetation parameters with GPS multipath observables (signal-to-noise-ratio (SNR), code pseudorange and carrier phase observables). The trunk layer and its corresponding scattering mechanisms are ignored since GPS-MR is not suitable for high forest monitoring due to the coherence of direct and reflected signals. Based on this new model, the developed simulator can present how the GPS signals (L1 and L2 carrier frequencies, C/A, P(Y) and L2C modulations) are transmitted (scattered and absorbed) through vegetation medium and received by GPS receivers. Simulation results show that the wheat will decrease the amplitudes of GPS multipath observables (SNR, phase and code), if we increase the vegetation moisture contents or the scatters sizes (stem or leaf). Although the Specular-Ground component dominates the total specular scattering, vegetation covered ground soil moisture has almost no effects on the final multipath signatures. Our simulated results are consistent with previous results for environmental parameter detections by GPS-MR. PMID:28587255

  2. \\vspace{8mm}Inclusion of vegetation in the Town Energy Balance model for modelling urban green areas

    NASA Astrophysics Data System (ADS)

    Lemonsu, A.; Masson, V.; Shashua-Bar, L.; Erell, E.; Pearlmutter, D.

    2012-11-01

    Cities impact both local climate, through urban heat islands and global climate, because they are an area of heavy greenhouse gas release into the atmosphere due to heating, air conditioning and traffic. Including more vegetation into cities is a planning strategy having possible positive impacts for both concerns. Improving vegetation representation into urban models will allow us to address more accurately these questions. This paper presents an improvement of the Town Energy Balance (TEB) urban canopy model. Vegetation is directly included inside the canyon, allowing shadowing of grass by buildings, better representation of urban canopy form and, a priori, a more accurate simulation of canyon air microclimate. The surface exchanges over vegetation are modelled with the well-known Interaction Soil Biosphere Atmosphere (ISBA) model that is integrated in the TEB's code architecture in order to account for interactions between natural and built-up covers. The design of the code makes possible to plug and use any vegetation scheme. Both versions of TEB are confronted to experimental data issued from a field campaign conducted in Israel in 2007. Two semi-enclosed courtyards arranged with bare soil or watered lawn were instrumented to evaluate the impact of landscaping strategies on microclimatic variables and evapotranspiration. For this case study, the new version of the model with integrated vegetation performs better than if vegetation is treated outside the canyon. Surface temperatures are closer to the observations, especially at night when radiative trapping is important. The integrated vegetation version simulates a more humid air inside the canyon. The microclimatic quantities (i.e., the street-level meteorological variables) are better simulated with this new version. This opens opportunities to study with better accuracy the urban microclimate, down to the micro (or canyon) scale.

  3. Middle Pliocene vegetation: Reconstructions, paleoclimatic inferences, and boundary conditions for climate modeling

    USGS Publications Warehouse

    Thompson, R.S.; Fleming, R.F.

    1996-01-01

    The general characteristics of global vegetation during the middle Pliocene warm period can be reconstructed from fossil pollen and plant megafossil data. The largest differences between Pliocene vegetation and that of today occurred at high latitudes in both hemispheres, where warming was pronounced relative to today. In the Northern Hemisphere coniferous forests lived in the modern tundra and polar desert regions, whereas in the Southern Hemisphere southern beech apparently grew in coastal areas of Antarctica. Pliocene middle latitude vegetation differed less, although moister-than-modern conditions supported forest and woodland growth in some regions now covered by steppe or grassland. Pliocene tropical vegetation reflects essentially modern conditions in some regions and slightly cooler-than-or warmer-than- modern climates in other areas. Changes in topography induced by tectonics may be responsible for many of the climatic changes since the Pliocene in both middle and lower latitudes. However, the overall latitudinal progression of climatic conditions on land parallels that seen in the reconstruction of middle Pliocene sea-surface temperatures. Pliocene paleovegetational data was employed to construct a 2????2?? global grid of estimated mid-Pliocene vegetational cover for use as boundary conditions for numerical General Circulation Model simulations of middle Pliocene climates. Continental outlines and topography were first modified to represent the Pliocene landscape on the 2????2?? grid. A modern 1????1?? vegetation grid was simplified and mapped on this Pliocene grid, and then modified following general geographic trends evident in the Pliocene paleovegetation data set.

  4. Assessing and Adapting LiDAR-Derived Pit-Free Canopy Height Model Algorithm for Sites with Varying Vegetation Structure

    NASA Astrophysics Data System (ADS)

    Scholl, V.; Hulslander, D.; Goulden, T.; Wasser, L. A.

    2015-12-01

    Spatial and temporal monitoring of vegetation structure is important to the ecological community. Airborne Light Detection and Ranging (LiDAR) systems are used to efficiently survey large forested areas. From LiDAR data, three-dimensional models of forests called canopy height models (CHMs) are generated and used to estimate tree height. A common problem associated with CHMs is data pits, where LiDAR pulses penetrate the top of the canopy, leading to an underestimation of vegetation height. The National Ecological Observatory Network (NEON) currently implements an algorithm to reduce data pit frequency, which requires two height threshold parameters, increment size and range ceiling. CHMs are produced at a series of height increments up to a height range ceiling and combined to produce a CHM with reduced pits (referred to as a "pit-free" CHM). The current implementation uses static values for the height increment and ceiling (5 and 15 meters, respectively). To facilitate the generation of accurate pit-free CHMs across diverse NEON sites with varying vegetation structure, the impacts of adjusting the height threshold parameters were investigated through development of an algorithm which dynamically selects the height increment and ceiling. A series of pit-free CHMs were generated using three height range ceilings and four height increment values for three ecologically different sites. Height threshold parameters were found to change CHM-derived tree heights up to 36% compared to original CHMs. The extent of the parameters' influence on modelled tree heights was greater than expected, which will be considered during future CHM data product development at NEON. (A) Aerial image of Harvard National Forest, (B) standard CHM containing pits, appearing as black speckles, (C) a pit-free CHM created with the static algorithm implementation, and (D) a pit-free CHM created through varying the height threshold ceiling up to 82 m and the increment to 1 m.

  5. Reconstructing marginality: a new model of cultural diversity in nursing.

    PubMed

    Southwick, Margaret; Polaschek, Nick

    2014-05-01

    This article presents a new model of cultural diversity in nursing that critically reconstructs the concept of marginality that underpins other models. Rather than viewing the marginal as "other," marginality is redefined as the space in between the dominant cultural reality and the cultural realities of minority groups located within a society. Members of a minority cultural group who become skilled in the difficult process of negotiating this in-between space open the possibility of transformation within nursing education and practice. This model has been applied in a study of the experience of nursing students of Pacific ethnicity in New Zealand. Subsequently, an undergraduate Pacific nursing program was developed, with greatly increased success rates in registration of Pacific nurses. This model of cultural diversity can also be used to understand nursing practice involving people from minority cultures or other socially excluded categories. Copyright 2014, SLACK Incorporated.

  6. Global terrestrial ecosystem models of productivity and nutrient cycling and vegetation response to climate

    SciTech Connect

    Kercher, J.R.; Chambers, J.Q.; Axelrod, M.C. )

    1993-06-01

    We are developing two global terrestrial ecosystem models (TERRA and HABITAT) to be coupled to atmospheric and oceanic models in an Earth System Model. TERRA is a model of ecosystem productivity and biogeochemical cycling covering the Earth's land surface as a grid of independent, local models. HABITAT is being designed as a gridded, dynamic model of vegetation response to climate. The TERRA grid cell models are calibrated to 17 vegetation types. The parameter for maximum gross primary productivity was found to average (2.4 +/- 1.4 s.d.) x 10[sup 4] g m[sup [minus]2] y[sup [minus]1] across the 17 types. Maximum rate of nitrogen uptake by vegetation averaged 13 +/- 3 g m[sup [minus]2] y[sup [minus]1] for all forest types, 9 +/- 3 for all woodland and savanna types, and 5 +/- 2 for all grassland, tundra, and shrubland types. Preliminary analysis for designing HABITAT suggests that total annual precipitation and average monthly temperature do not resolve vegetation types. This result emphasizes the need for constructing a set of climatic variables that simplify the biological response.

  7. Modelling the response of fresh groundwater to climate and vegetation changes in coral islands

    NASA Astrophysics Data System (ADS)

    Comte, Jean-Christophe; Join, Jean-Lambert; Banton, Olivier; Nicolini, Eric

    2014-12-01

    In coral islands, groundwater is a crucial freshwater resource for terrestrial life, including human water supply. Response of the freshwater lens to expected climate changes and subsequent vegetation alterations is quantified for Grande Glorieuse, a low-lying coral island in the Western Indian Ocean. Distributed models of recharge, evapotranspiration and saltwater phytotoxicity are integrated into a variable-density groundwater model to simulate the evolution of groundwater salinity. Model results are assessed against field observations including groundwater and geophysical measurements. Simulations show the major control currently exerted by the vegetation with regards to the lens morphology and the high sensitivity of the lens to climate alterations, impacting both quantity and salinity. Long-term changes in mean sea level and climatic conditions (rainfall and evapotranspiration) are predicted to be responsible for an average increase in salinity approaching 140 % (+8 kg m-3) when combined. In low-lying areas with high vegetation density, these changes top +300 % (+10 kg m-3). However, due to salinity increase and its phytotoxicity, it is shown that a corollary drop in vegetation activity can buffer the alteration of fresh groundwater. This illustrates the importance of accounting for vegetation dynamics to study groundwater in coral islands.

  8. Quantifying Uncertainties from Presence Data Sampling Methods for Species Distribution Modeling: Focused on Vegetation.

    NASA Astrophysics Data System (ADS)

    Sung, S.; Kim, H. G.; Lee, D. K.; Park, J. H.; Mo, Y.; Kil, S.; Park, C.

    2016-12-01

    The impact of climate change has been observed throughout the globe. The ecosystem experiences rapid changes such as vegetation shift, species extinction. In these context, Species Distribution Model (SDM) is one of the popular method to project impact of climate change on the ecosystem. SDM basically based on the niche of certain species with means to run SDM present point data is essential to find biological niche of species. To run SDM for plants, there are certain considerations on the characteristics of vegetation. Normally, to make vegetation data in large area, remote sensing techniques are used. In other words, the exact point of presence data has high uncertainties as we select presence data set from polygons and raster dataset. Thus, sampling methods for modeling vegetation presence data should be carefully selected. In this study, we used three different sampling methods for selection of presence data of vegetation: Random sampling, Stratified sampling and Site index based sampling. We used one of the R package BIOMOD2 to access uncertainty from modeling. At the same time, we included BioCLIM variables and other environmental variables as input data. As a result of this study, despite of differences among the 10 SDMs, the sampling methods showed differences in ROC values, random sampling methods showed the lowest ROC value while site index based sampling methods showed the highest ROC value. As a result of this study the uncertainties from presence data sampling methods and SDM can be quantified.

  9. [Hyperspectral remote sensing estimation models on vegetation coverage of natural grassland].

    PubMed

    Liu, Zhanyu; Huang, Jingfeng; Wu, Xinhong; Dong, Yongping; Wang, Fumin; Liu, Pengtao

    2006-06-01

    By using ASD FieldSpec Pro FR spectroradiometer, the spectral measurement of natural grassland in Xilingole Leaguer of Inner Mongolia was performed, with the vegetation coverage of natural grassland calculated, and the correlation of 25 hyperspectral feature variables with the vegetation coverage of natural grassland was analyzed. The results showed that there were 17 variables correlated significantly with the vegetation coverage of natural grassland, among which, the correlation coefficient between vegetation coverage and the area of red edge peak calculated as the sum of the amplitudes between 680 nm and 780 nm (sigma dr 680 - 780 nm) was the highest, with the value of 0.781. The basic experimental data including the vegetation coverage and canopy reflectance of natural grassland were classified into two groups. One group was used as the training sample to build the regression models with one-sample linear method, nonlinear method, and stepwise analysis method, while the other was used as the testing sample to test the precision of regression models. It was suggested that the variable of the area of red edge peak calculated as the sum of amplitudes between 680 nm and 780 nm (sigma dr 680 - 780 nm) was the best one to univariate general linear model, with a standard deviation of 10.4% and an estimation precision of 83.99%, while the stepwise regression technique was not effective to estimate the grassland coverage with raw hyperspectral canopy reflectance.

  10. Comparison between microwave coherent and incoherent scattering models for wetland vegetation in Poyang Lake area

    NASA Astrophysics Data System (ADS)

    Xu, Tao; Liao, Jingjuan

    2014-11-01

    In order to reveal more deeply the scattering characteristics of wetland vegetation and determine the microwave scattering model suitable for the inversion of wetland vegetation parameters, the comparison and analysis between microwave coherent and incoherent scattering models for wetland vegetation in Poyang Lake area were performed in this paper. In the research, we proposed a coherent scattering model exclusive for wetland vegetation, in which, Generalized Rayleigh-Gans (GRG) approach and infinite-length dielectric cylinder were used to calculate single-scattering matrices of wetland vegetation leaves and stalks. In addition, coherent components produced from interaction among the scattering mechanisms and different scatterers were also considered and this coherent model was compared with Michigan Microwave Canopy Scattering (MIMICS) model. The measured data collected in 2011 in Poyang Lake wetland were used as the input parameters of the coherent and incoherent models. We simulated backscattering coefficients of VV, VH and HH polarization at C band and made a comparison between the simulation results and C-band data from the Radarsat-2 satellite. For both coherent and incoherent scattering model, simulation results for HH and VV polarization were better than the simulation results for HV polarization. In addition, comparisons between coherent and incoherent scattering models proved that the coherence triggered by the scattering mechanism and different scatterers can't be ignored. In the research, we analyzed differences between coherent and incoherent scattering models with change of incident angle. In most instances, the difference between coherent and incoherent scattering models is of the order of several dB.

  11. Global quantifiction of vegetation rooting depth for hydrological modelling

    NASA Astrophysics Data System (ADS)

    Yuting, Yuting; Donohue, Randall; McVicar, Tim

    2017-04-01

    Plant rooting depth (Zr) is a key parameter in hydrological and biogeochemical models, yet the global spatial distribution of Zr is largely unknown due to the difficulties in its direct measurement. Moreover, Zr observations are usually only representative of a single plant or several plants, which can differ greatly from the effective Zr over a modelling unit (e.g., catchment or grid-box). Here, we provide a global parameterization of an analytical Zr model that balances the marginal carbon cost and benefit of deeper roots, and produce a climatological (i.e., 1982-2010 average) global Zr map. To test the Zr estimates, we apply the estimated Zr in a highly transparent hydrological model (i.e., the Budyko-Choudhury-Porporato (BCP) model) to estimate mean annual actual evapotranspiration (E) across the globe. We then compare the estimated E with both water balance-based E observations at 32 major catchments and satellite grid-box retrievals across the globe. Our results show that the BCP model, when implemented with Zr estimated herein, optimally reproduced the spatial pattern of E at both scales and provides improved model outputs when compared to BCP model results from two already existing global Zr datasets. These results suggest that our Zr estimates can be effectively used in state-of-the-art hydrological models, and potentially biogeochemical models, where the determination of Zr currently largely relies on biome type-based look-up tables.

  12. [Effects of different vegetation restoration patterns on the diversity of soil nitrogen-fixing microbes in Hulunbeier sandy land, Inner Mongolia of North China].

    PubMed

    Li, Gang; Wang, Li-Juan; Li, Yu-Jie; Qiao, Jiang; Zhang, Hai-Fang; Song, Xiao-Long; Yang, Dian-Lin

    2013-06-01

    By using polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) and sequence analysis, this paper studied the nifH gene diversity and community structure of soil nitrogen-fixing microbes in Hulunbeier sandy land of Inner Mongolia under four years management of five vegetation restoration modes, i. e., mixed-planting of Agropyron cristatum, Hedysarum fruticosum, Caragana korshinskii, and Elymus nutans (ACHE) and of Agropyron cristatum and Hedysarum fruticosum (AC), and mono-planting of Caragana korshinskii (UC), Agropyron cristatum (UA), and Hedysarum fruticosum (UH), taking the bare land as the control (CK). There existed significant differences in the community composition of nitrogen-fixing microbes among the five vegetation restoration patterns. The Shannon index of the nifH gene was the highest under ACHE, followed by under AC, UC, UA, and UH, and the lowest in CK. Except that UH and CK had less difference in the Shannon index, the other four vegetation restoration modes had a significantly higher Shannon index than CK (P < 0.05). The phylogenetic analysis showed that the soil nitrogen-fixing microbes under UA, UH, and UC were mainly of cyanobacteria, but the soil nitrogen-fixing microbes under AC and ACHE changed obviously, mainly of proteobacteria, and also of cyanobacteria. The canonical correlation analysis showed that the soil total phosphorus, available phosphorus, total nitrogen, and nitrate nitrogen contents under the five vegetation restoration modes had significant effects on the nitrogen-fixing microbial communities, and there existed significant correlations among the soil total phosphorus, available phosphorus, total nitrogen, and nitrate nitrogen. It was suggested that the variations of the community composition of soil nitrogen-fixing microbes under the five vegetation restoration modes were resulted from the interactive and combined effects of the soil physical and chemical factors.

  13. a Radiative Transfer Equation/phase Function Approach to Vegetation Canopy Reflectance Modeling

    NASA Astrophysics Data System (ADS)

    Randolph, Marion Herbert

    Vegetation canopy reflectance models currently in use differ considerably in their treatment of the radiation scattering problem, and it is this fundamental difference which stimulated this investigation of the radiative transfer equation/phase function approach. The primary objective of this thesis is the development of vegetation canopy phase functions which describe the probability of radiation scattering within a canopy in terms of its biological and physical characteristics. In this thesis a technique based upon quadrature formulae is used to numerically generate a variety of vegetation canopy phase functions. Based upon leaf inclination distribution functions, phase functions are generated for plagiophile, extremophile, erectophile, spherical, planophile, blue grama (Bouteloua gracilis), and soybean canopies. The vegetation canopy phase functions generated are symmetric with respect to the incident and exitant angles, and hence satisfy the principle of reciprocity. The remaining terms in the radiative transfer equation are also derived in terms of canopy geometry and optical properties to complete the development of the radiative transfer equation/phase function description for vegetation canopy reflectance modeling. In order to test the radiative transfer equation/phase function approach the iterative discrete ordinates method for solving the radiative transfer equation is implemented. In comparison with field data, the approach tends to underestimate the visible reflectance and overestimate infrared reflectance. The approach does compare well, however, with other extant canopy reflectance models; for example, it agrees to within ten to fifteen percent of the Suits model (Suits, 1972). Sensitivity analysis indicates that canopy geometry may influence reflectance as much as 100 percent for a given wavelength. Optical thickness produces little change in reflectance after a depth of 2.5 (Leaf area index of 4.0) is reached, and reflectance generally increases

  14. Vegetation influence on runoff and sediment yield in the Andes region: observation and modelling

    NASA Astrophysics Data System (ADS)

    Braud, I.; Vich, A. I. J.; Zuluaga, J.; Fornero, L.; Pedrani, A.

    2001-12-01

    The Precordillera of the Andes Mountains (Mendoza, Argentina) is prone to severe flash floods, caused by heavy rainfall events of short duration and high intensities. Two catchments were instrumented in order to study the rainfall-runoff process and soil management impact on runoff and/or sediment yield. In the first catchment (Divisadero Largo, DL, 5.47 km 2), characterized by a large heterogeneity of surface geology, a data set of about 50 rainfall-runoff events covering the 1983-1994 period was available. Vegetation cover changed significantly after the catchment was enclosed in 1989-1990. This change was successfully mapped using Landsat TM image analysis. The second catchment (Cuenca Aluvional Piloto, CAP, 35 ha), the soil of which was homogeneous, was instrumented in 1992 for total runoff and sediment yield measurements. Three small plots of 3×10 m 2 (bare soil, 42 and 60% vegetation cover) and three sub catchments (2-4.5 ha) were delimited with different average vegetation cover. Data analysis showed the difficulty in relating runoff volume and sediment yield to simple descriptors of the catchments such as the average slope and/or the average vegetation cover. The DL and CAP catchments were modelled using the Areal Non Point Source Watershed Environment Response Simulation (ANSWERS) model with contrasting results. Good agreement between model and observation could be achieved after calibration on the 3×10 m 2 plots, but the model failed to correctly reproduce runoff on the three 2-4.5 ha CAP sub-catchments using the values calibrated on the small plots. Better results were obtained on the larger and heterogeneous DL basin, where surface geology variations and rainfall variability seemed to be the most influential factors. In this case, no sensitivity to vegetation coverage changes, induced when enclosing the catchment, was found. On the other hand, the model proved sensitive to differences in vegetation cover at smaller scales when the geology was

  15. 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

  16. A spatial simulation model of hydrology and vegetation dynamics in semi-permanent prairie wetlands

    USGS Publications Warehouse

    Poiani, Karen A.; Johnson, W. Carter

    1993-01-01

    The objective of this study was to construct a spatial simulation model of the vegetation dynamics in semi-permanent prairie wetlands. A hydrologic submodel estimated water levels based on precipitation, runoff, and potential evapotranspiration. A vegetation submodel calculated the amount and distribution of emergent cover and open water using a geographic information system. The response of vegetation to water-level changes was based on seed bank composition, seedling recruitment and establishment, and plant survivorship. The model was developed and tested using data from the Cottonwood Lake study site in North Dakota. Data from semi-permanent wetland P1 were used to calibrate the model. Data from a second wetland, P4, were used to evaluate model performance. Simulation results were compared with actual water data from 1797 through 1989. Test results showed that differences between calculated and observed water levels were within 10 cm 75% of the time. Open water over the past decade ranged from 0 to 7% in wetland P4 and from 0 to 8% in submodel simulations. Several model parameters including evapotranspiration and timing of seedling germination could be improved with more complex techniques or relatively minor adjustments. Despite these differences the model adequately represented vegetation dynamics of prairie wetlands and can be used to examine wetland response to natural or human-induce