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

NASA Astrophysics Data System (ADS)

Sewerniak, Piotr; Jankowski, Michał

2017-07-01

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

Above vs. belowground plant biomass along a barrier island: Implications for dune stabilization.

PubMed

Charbonneau, Bianca R; Wnek, John P; Langley, J Adam; Lee, Gina; Balsamo, Ronald A

2016-11-01

Coastal regions are inherently and increasingly vulnerable and geomorphologically unstable, yet are invaluable economic and residential hubs. Dunes are dynamic buffers to erosion and the most natural, economical, and effective defense for coastal communities. Vegetation is integral to dune structure as it facilitates accretion and stabilization. Differences in the vegetation and root density likely translate to variability in coastal erosion prevention, but this notion has been largely unconsidered. We directly compared stabilizing factors, depth and density, of the root systems of two dominant mid-Atlantic dune plant species, native American beach grass (Ammophila breviligulata) and invasive Asiatic sand sedge (Carex kobomugi). Despite high plant density, C. kobomugi is targeted for removal in restoration efforts as its roots are assumed to provide less effective stabilization than A. breviligulata. We collected 30 cores and hand dug 14 A. breviligulata ramets at Island Beach State Park, New Jersey to examine biomass, root:shoot ratios, and root density. C. kobomugi had a more extensive root system with a root:shoot ratio of 11.36:1 compared to 1.62:1 for A. breviligulata. Similarly, cores 60 cm deep and 7.6 cm wide were sufficient to attain fully intact A. breviligulata roots, which did not extend deeper than 40 cm, but insufficient for C. kobomugi roots which extended beyond the sampling system vertically and horizontally. Scaling these findings to m(-2), aboveground biomass is relatively equal, but C. kobomugi had over 700% more root mass m(-2) than A. breviligulata. These results have strong implications for dune management. The root system of C. kobomugi may be better adapted to stabilize dunes and thus protect coastal areas during small and large-scale perturbations than previously supposed. This is a unique situation whereby the creation of monocultures will hyperstabilize dunes and make them more resistant to erosion at the cost of reduced biodiversity within the framework of resiliency. Published by Elsevier Ltd.

Complexity confers stability: Climate variability, vegetation response and sand transport on longitudinal sand dunes in Australia's deserts

NASA Astrophysics Data System (ADS)

Hesse, Paul P.; Telfer, Matt W.; Farebrother, Will

2017-04-01

The relationship between antecedent precipitation, vegetation cover and sand movement on sand dunes in the Simpson and Strzelecki Deserts was investigated by repeated (up to four) surveys of dune crest plots (≈25 × 25 m) over a drought cycle (2002-2012) in both winter (low wind) and spring (high wind). Vegetation varied dramatically between surveys on vegetated and active dune crests. Indices of sand movement had significant correlations with vegetation cover: the depth of loose sand has a strong inverse relationship with crust (cyanobacterial and/or physical) while the area covered by ripples has a strong inverse relationship with the areal cover of vascular plants. However, the relationship between antecedent rainfall and vegetation cover was found to be complex. We tentatively identify two thresholds; (1) >10 mm of rainfall in the preceding 90 days leads to rapid and near total cover of crust and/or small plants <50 cm tall, and (2) >400 mm of rainfall in the preceding three years leads to higher cover of persistent and longer-lived plants >50 cm tall. These thresholds were used to predict days of low vegetation cover on dune crests. The combination of seasonality of predicted bare-crest days, potential sand drift and resultant sand drift direction explains observed patterns of sand drift on these dunes. The complex vegetation and highly variable rainfall regime confer meta-stability on the dunes through the range of responses to different intervals of antecedent rainfall and non-linear growth responses. This suggests that the geomorphic response of dunes to climate variation is complex and non-linear.

Environmental Assessment for the General Plan and Maintenance of Patrick Air Force Base, Florida

DTIC Science & Technology

2005-05-01

established potential to invade and disrupt native plant communities. Brazilian pepper, Australian pine, Melaleuca, cogon grass (Imperata cylindrical...other areas on base. Cogon grass is a hardy, invasive that has not been identified on PAFB, but has been observed in several Brevard County locations...narrow strip of vegetation bordered by the Atlantic Ocean, State Route A1A, Base Housing, or areas of mowed grass . Erosion has affected these dunes

Coupled topographic and vegetation patterns in coastal dunes: Remote sensing observations and ecomorphodynamic implications

NASA Astrophysics Data System (ADS)

Yousefi Lalimi, F.; Silvestri, S.; Moore, L. J.; Marani, M.

2017-01-01

Vegetation plays a key role in stabilizing coastal dunes and barrier islands by mediating sand transport, deposition, and erosion. Dune topography, in turn, affects vegetation growth, by determining local environmental conditions. However, our understanding of vegetation and dune topography as coupled and spatially extensive dynamical systems is limited. Here we develop and use remote sensing analyses to quantitatively characterize coastal dune ecotopographic patterns by simultaneously identifying the spatial distribution of topographic elevation and vegetation biomass. Lidar-derived leaf area index and hyperspectral-derived normalized difference vegetation index patterns yield vegetation distributions at the whole-system scale which are in agreement with each other and with field observations. Lidar-derived concurrent quantifications of biomass and topography show that plants more favorably develop on the landward side of the foredune crest and that the foredune crestline marks the position of an ecotone, which is interpreted as the result of a sheltering effect sharply changing local environmental conditions. We conclude that the position of the foredune crestline is a chief ecomorphodynamic feature resulting from the two-way interaction between vegetation and topography.

Development of a coastal dune vulnerability index for Mediterranean ecosystems: A useful tool for coastal managers?

NASA Astrophysics Data System (ADS)

Ciccarelli, D.; Pinna, M. S.; Alquini, F.; Cogoni, D.; Ruocco, M.; Bacchetta, G.; Sarti, G.; Fenu, G.

2017-03-01

Coastal dune ecosystems have been severely degraded as a result of excessive natural resource exploitation, urbanisation, industrial growth, and worldwide tourism. Coastal management often requires the use of vulnerability indices to facilitate the decision-making process. The main objective of this study was to develop a Mediterranean dune vulnerability index (MDVI) for sandy coasts, starting from the existing dune vulnerability index (DVI) proposed by Garcia-Mora et al. (2001) related to the oceanic coasts. Given that the Mediterranean sandy coasts are quite different from the Atlantic coasts, several adjustments and integrations were introduced. Our proposed index is based on the following five main group of factors: geomorphological conditions of the dune systems (GCD), marine influence (MI), aeolian effect (AE), vegetation condition (VC), and human effect (HE), for a total of 51 variables derived (and adapted) from the bibliography or proposed for the first time in this study. For each coastal site, a total vulnerability index, ranging from 0 (very low vulnerability) to 1 (very high vulnerability), was calculated as the unweighted average of the five partial vulnerability indices. Index computation was applied to 23 coastal dune systems of two different contexts in Italy, i.e. peninsular and continental island territories representative of the W-Mediterranean Basin, in order to compare the dune systems with different geomorphology, shoreline dynamics, and human pressure. In particular, our research addressed the following two questions: (1) Which variables are the most critical for the Italian coastal systems? (2) How can the coastal dune vulnerability index be used to develop appropriate strategies of conservation and management for these ecosystems? Cluster analysis and non-metric multidimensional scaling separated the peninsular from the insular sites, both of which were characterised by low to moderate values of vulnerability (0.32 < MDVI < 0.49). The most critical factors for the coastal systems examined in this study were marine negative influence, low stabilising ability of vegetation, and human disturbance. Hence, coastal managers are encouraged to plan specific management actions such as protection of foredunes from marine factors (particularly erosion), to promote dune formation with the reintroduction of native dune builder species and to minimise human pressure where vulnerability depends on these variables.

Lateral vegetation growth rates exert control on coastal foredune hummockiness and coalescing time

NASA Astrophysics Data System (ADS)

Goldstein, Evan B.; Moore, Laura J.; Durán Vinent, Orencio

2017-08-01

Coastal foredunes form along sandy, low-sloped coastlines and range in shape from continuous dune ridges to hummocky features, which are characterized by alongshore-variable dune crest elevations. Initially scattered dune-building plants and species that grow slowly in the lateral direction have been implicated as a cause of foredune hummockiness. Our goal in this work is to explore how the initial configuration of vegetation and vegetation growth characteristics control the development of hummocky coastal dunes including the maximum hummockiness of a given dune field. We find that given sufficient time and absent external forcing, hummocky foredunes coalesce to form continuous dune ridges. Model results yield a predictive rule for the timescale of coalescing and the height of the coalesced dune that depends on initial plant dispersal and two parameters that control the lateral and vertical growth of vegetation, respectively. Our findings agree with previous observational and conceptual work - whether or not hummockiness will be maintained depends on the timescale of coalescing relative to the recurrence interval of high-water events that reset dune building in low areas between hummocks. Additionally, our model reproduces the observed tendency for foredunes to be hummocky along the southeast coast of the US where lateral vegetation growth rates are slower and thus coalescing times are likely longer.

Geomorphology and reflectance patterns of vegetation-covered dunes at the Tsodilo Hills, north-west Botswana

NASA Technical Reports Server (NTRS)

Jacobberger, P. A.; Hooper, D. M.

1991-01-01

Seasonal reflectance variations in semigrid environments provide a means of assessing vegetation health and density as well as monitoring landform processes. Multitemporal Landsat Thematic Mapper scenes with field measurements are used to map geomorphology and vegetation density in a stabilized dune environment and to measure seasonal reflectance changes for a series of ten geomorphological and vegetation units on the Kalahari-age linear dunes. Units were chosen based on differences in landform and proportion of trees, forbs and bare soil. Reflectance curves and normalized-difference vegetation indices (NDVI) show that dune crests have the strongest seasonal variability in color and brightness. The geomorphological link with reflectance and NDVI values are linked to biomass production and zoning of vegetation with slope, drainage and subtle soil differences.

Evidence for community structure and habitat partitioning in coastal dune stiletto flies at the Guadalupe-Nipomo dunes system, California

PubMed Central

Holston, Kevin C.

2005-01-01

This study provides empirical evidence for habitat selection by North American species of stiletto flies (Diptera: Therevidae), based on local distributions of adults and immatures, and the first hypothesis of community assemblages proposed for a stiletto fly community. Sites at three localities within the Guadalupe-Nipomo dune system were sampled for stiletto flies in 1997 and 2001 by sifting sand, malaise trapping, and hand netting. Nine species were collected from four ecological zones and three intermediate ecological zones: Acrosathe novella (Coquillett), Brachylinga baccata (Loew), Nebritus powelli (Webb and Irwin), Ozodiceromyia sp., Pherocera sp., Tabudamima melanophleba (Loew), Thereva comata Loew, Thereva elizabethae Holston and Irwin, and Thereva fucata Loew. Species associations of adults and larvae with habitats and ecological zones were consistent among sites, suggesting that local distributions of coastal dune stiletto fly species are influenced by differences in habitat selection. In habitats dominated by the arroyo willow,Salix lasiolepsis, stiletto fly larvae of three species were collected in local sympatry, demonstrating that S. lasiolepsis stands along stabilized dune ridges can provide an intermediate ecological zone linking active dune and riparian habitat in the Guadalupe-Nipomo dune system. Sites dominated by European beach grass, Ammophilia arenaria, blue gum, Eucalyptus globulus, and Monterey cypress, Cupressus macrocarpa, are considered unsuitable for stiletto flies, which emphasizes the importance of terrestrial habitats with native vegetation for stiletto fly species. The local distributions of stiletto fly species at the Guadalupe-Nipomo dune system allow the community to be divided into three assemblages; active dune, pioneer scrub, and scrub-riparian. These assemblages may be applicable to other coastal dune stiletto fly communities, and may have particular relevance to stiletto fly species collected in European coastal dunes. The results from this study provide a descriptive framework for studies testing habitat selection in coastal dune stiletto fly species and inform conservation of threatened dune insects. PMID:17119624

Conceptual models of the evolution of transgressive dune field systems

NASA Astrophysics Data System (ADS)

A. Hesp, Patrick

2013-10-01

This paper examines the evolutionary paths of some transgressive dune fields that have formed on different coasts of the world, and presents some initial conceptual models of system dynamics for transgressive dune sheets and dune fields. Various evolutionary pathways are conceptualized based on a visual examination of dune fields from around the world. On coasts with high sediment supply, dune sheets and dune fields tend to accumulate as large scale barrier systems with little colonization of vegetation in arid-hyper to arid climate regimes, and as multiple, active discrete phases of dune field and deflation plain couplets in temperate to tropical environments. Active dune fields tend to be singular entities on coasts with low to moderate sediment supply. Landscape complexity and vegetation richness and diversity increases as dune fields evolve from simple active sheets and dunes to single and multiple deflation plains and basins, precipitation ridges, nebkha fields and a host of other dune types associated with vegetation (e.g. trailing ridges, slacks, remnant knobs, gegenwalle ridges and dune track ridges, ‘tree islands' and ‘bush pockets'). Three principal scenarios of transgressive dune sheet and dune field development are discussed, including dune sheets or dune fields evolving directly from the backshore, development following foredune and/or dune field erosion, and development from the breakdown or merging of parabolic dunes. Various stages of evolution are outlined for each scenario. Knowledge of evolutionary patterns and stages in coastal dune fields is very limited and caution is urged in attempts to reverse, change and/or modify dune fields to ‘restore' some perceived loss of ecosystem or dune functioning.

Conceptual models of the evolution of transgressive dune field systems

NASA Astrophysics Data System (ADS)

Hesp, Patrick A.

2013-10-01

This paper examines the evolutionary paths of some transgressive dune fields that have formed on different coasts of the world, and presents some initial conceptual models of system dynamics for transgressive dune sheets and dune fields. Various evolutionary pathways are conceptualized based on a visual examination of dune fields from around the world. On coasts with high sediment supply, dune sheets and dune fields tend to accumulate as large scale barrier systems with little colonization of vegetation in arid-hyper to arid climate regimes, and as multiple, active discrete phases of dune field and deflation plain couplets in temperate to tropical environments. Active dune fields tend to be singular entities on coasts with low to moderate sediment supply. Landscape complexity and vegetation richness and diversity increases as dune fields evolve from simple active sheets and dunes to single and multiple deflation plains and basins, precipitation ridges, nebkha fields and a host of other dune types associated with vegetation (e.g. trailing ridges, slacks, remnant knobs, gegenwalle ridges and dune track ridges, 'tree islands' and 'bush pockets'). Three principal scenarios of transgressive dune sheet and dune field development are discussed, including dune sheets or dune fields evolving directly from the backshore, development following foredune and/or dune field erosion, and development from the breakdown or merging of parabolic dunes. Various stages of evolution are outlined for each scenario. Knowledge of evolutionary patterns and stages in coastal dune fields is very limited and caution is urged in attempts to reverse, change and/or modify dune fields to 'restore' some perceived loss of ecosystem or dune functioning.

System Controls on the South Texas Sand Sheet

NASA Astrophysics Data System (ADS)

Barrineau, Clifton Patrick

Semi-stabilized dune systems are important indicators of Quaternary drought variability across central North America. The South Texas sand sheet (STSS) is the southernmost relict dune system in central North America and is exposed to higher evapotranspiration and moisture variability than similar landscapes farther north. This study uses multi-scale analysis of LiDAR data, geophysical surveys, optically stimulated luminescence dates of core samples, and X-ray fluorescence analysis to identify historical periods of desertification across the STSS. These data suggest long-term relationships between climate, ecological disturbances, geological framework, and desertification. Aeolian activations dated at ca. 75, 230, 2000, 4100, and 6600 yr bp correspond to periods of persistent regional drought, changes in sediment supply, and anthropogenic disturbances of native ecology. From these results it appears that regionalized activation in semi-stabilized dune systems is controlled primarily by climatic variations that reduce the overall moisture available for maintaining vigorous vegetation growth, while localized activation patterns depend more on stresses related to site-specific morphodynamics as well as human activity. With enhanced aridity forecast for much of central North America through the 21 st century, understanding the specific thresholds of desertification is an important step towards building a conceptual model of desertification in semi-stabilized dune landscapes.

Dune formation on the Cooper Creek floodplain, Strzelecki Desert, Australia - first results of morphodynamic simulations

NASA Astrophysics Data System (ADS)

Kryger, Mateusz; Bubenzer, Olaf; Parteli, Eric

2017-04-01

Linear Dunes, which align longitudinally to the resultant wind vector, are the prevailing type of the south-north trending and partially vegetated dunes in the Strzelecki Desert, Australia. However, particularly on the Cooper Creek floodplain near Innamincka, striking complex dune features consisting of transversely oriented east-west trending dunes occur. These transverse dunes extend over several kilometers and are superimposed by linear dunes that elongate northwards and are separated by sandy swales. The aeolian features in the Strzelecki Desert are the result of interrelated late quaternary aeolian and fluvial activity and serve, thus, as archives providing information about variations in palaeoclimate and potential changes in fluvial sediment supply and wind strength and directionality. However, since the dunes are currently mostly stabilized by vegetation, it is uncertain whether their formation can be explained by the contemporary wind systems. To understand the dynamic processes underlying the genesis of the dune field in the Strzelecki Desert, the role of vegetation and the wind regimes leading to the observed dune patterns must be elucidated. Here we investigate the formative processes of the dune features occurring on the Cooper Creek floodplain by means of morphodynamic modeling of aeolian sand transport and dune formation in presence of vegetation growth. Our simulations show that a source-bordering dune can be formed out of the sediments of seasonally exposed sandbars of the palaeo-Cooper system by a unidirectional wind, which explains the emergence of the transverse dunes in the field. Moreover, a shift in the wind regime to obtuse bidirectional wind flows combined with a rapid decrease in the vegetation cover leads to the formation of linear dunes on the surface and in the lee of the transverse dunes. These linear dunes elongate over several kilometers downwind as a result of the seasonal wind changes. The dune shapes obtained in our simulations agree well with the real dune morphologies when a low vegetation growth rate is applied in the model. Although geochronological investigations, reported in the literature, on the Cooper Creek floodplain did not show the linear dunes declining in age downwind (which suggests the adjacent swales or the transverse dune to be the sediment source), our simulations show that strikingly similar linear dune morphologies can be obtained by sediment influx due to saltation alone. In this case, the bars of the palaeo-Cooper system might as well have served as the sediment source for the formation of the linear dunes. Therefore, our results suggest that a long-distance transport extension model could also explain the linear dune formation, while previous geochronological investigations supported the wind-rift vertical extension and wind-rift vertical accretion models. The morphodynamic simulations may thus not only help to reconstruct the palaeoenvironment of the northern Strzelecki Desert, but also provide insights for the interpretation of the sediment archives located on the Cooper Creek alluvial fan.

Earth Observations taken by the Expedition 17 Crew

NASA Image and Video Library

2008-09-15

ISS017-E-016521 (15 Sept. 2008) --- Sandy Cape and Fraser Island, Australia are featured in this image photographed by an Expedition 17 crewmember on the International Space Station. Fraser Island, the world's largest sand island, includes Great Sandy National Park and is located along the coastline of Queensland, Australia. The island was designated a World Heritage site in 1992, in part due to its outstanding preservation of geological processes related to sand dune formation. According to scientists, the island's dune fields preserve a record of sand deposition and movement related to sea level rise and fall extending back over 700,000 years. In addition to sand dunes, the island also preserves an interesting range of vegetation -- including vine rainforest, stands of eucalypt trees, and mangroves -- and diverse fauna including crabs, parrots, sugar gliders and flying foxes. This view highlights the northernmost portion of the island, known as Sandy Cape. Active white sand dunes contrast with dark green vegetation that anchors older dune sets. Irregular patches of sand dunes surrounded by vegetation are known as sand blows (or blowouts), formed when the vegetation cover is disturbed -- by wind, fire, or human activities. The exposed underlying sand can then move and form new dunes, sometimes at rates of up to one meter per year. Coastal sand dune fields -- such as the one located along the eastern side of Sandy Cape (center) -- will remain active until anchored by vegetation, or until no more sand is available to form new dunes.

Environmental Controls and Eco-geomorphic Interactions of the Barchan-to-parabolic Dune Stabilisation and the Parabolic-to-barchan Dune Reactivation

NASA Astrophysics Data System (ADS)

Yan, Na; Baas, Andreas

2015-04-01

Parabolic dunes are one of a few common aeolian landforms which are highly controlled by eco-geomorphic interactions. Parabolic dunes, on the one hand, can be developed from highly mobile dune landforms, barchans for instance, in an ameliorated vegetation condition; or on the other hand, they can be reactivated and transformed back into mobile dunes due to vegetation deterioration. The fundamental mechanisms and eco-geomorphic interactions controlling both dune transformations remain poorly understood. To bridge the gap between complex processes involved in dune transformations on a relatively long temporal scale and real world monitoring records on a very limited temporal scale, this research has extended the DECAL model to incorporate 'dynamic' growth functions and the different 'growth' of perennial shrubs between growing and non-growing seasons, informed by field measurements and remote sensing analysis, to explore environmental controls and eco-geomorphic interactions of both types of dune transformation. A non-dimensional 'dune stabilising index' is proposed to capture the interactions between environmental controls (i.e. the capabilities of vegetation to withstand wind erosion and sand burial, the sandy substratum thickness, the height of the initial dune, and the sand transport potential), and establish the linkage between these controls and the geometry of a stabilising dune. An example demonstrates how to use the power-law relationship between the dune stabilising index and the normalised migration distance to assist in extrapolating the historical trajectories of transforming dunes. The modelling results also show that a slight increase in vegetation cover of an initial parabolic dune can significantly increase the reactivation threshold of climatic impact (both drought stress and wind strength) required to reactivate a stabilising parabolic dune into a barchan. Four eco-geomorphic interaction zones that govern a barchan-to-parabolic dune transformation and a parabolic-to-barchan dune transformation have been identified. These zones exhibit different characteristics and dynamics that are sensitive to changes in environmental forces, and can be potentially used as a proxy to monitor the mobility of a dune system.

Responses of dune plant communities to continental uplift from a major earthquake: sudden releases from coastal squeeze.

PubMed

Rodil, Iván F; Jaramillo, Eduardo; Hubbard, David M; Dugan, Jenifer E; Melnick, Daniel; Velasquez, Carlos

2015-01-01

Vegetated dunes are recognized as important natural barriers that shelter inland ecosystems and coastlines suffering daily erosive impacts of the sea and extreme events, such as tsunamis. However, societal responses to erosion and shoreline retreat often result in man-made coastal defence structures that cover part of the intertidal and upper shore zones causing coastal squeeze and habitat loss, especially for upper shore biota, such as dune plants. Coseismic uplift of up to 2.0 m on the Peninsula de Arauco (South central Chile, ca. 37.5º S) caused by the 2010 Maule earthquake drastically modified the coastal landscape, including major increases in the width of uplifted beaches and the immediate conversion of mid to low sandy intertidal habitat to supralittoral sandy habitat above the reach of average tides and waves. To investigate the early stage responses in species richness, cover and across-shore distribution of the hitherto absent dune plants, we surveyed two formerly intertidal armoured sites and a nearby intertidal unarmoured site on a sandy beach located on the uplifted coast of Llico (Peninsula de Arauco) over two years. Almost 2 years after the 2010 earthquake, dune plants began to recruit, then rapidly grew and produced dune hummocks in the new upper beach habitats created by uplift at the three sites. Initial vegetation responses were very similar among sites. However, over the course of the study, the emerging vegetated dunes of the armoured sites suffered a slowdown in the development of the spatial distribution process, and remained impoverished in species richness and cover compared to the unarmoured site. Our results suggest that when released from the effects of coastal squeeze, vegetated dunes can recover without restoration actions. However, subsequent human activities and management of newly created beach and dune habitats can significantly alter the trajectory of vegetated dune development. Management that integrates the effects of natural and human induced disturbances, and promotes the development of dune vegetation as natural barriers can provide societal and conservation benefits in coastal ecosystems.

Responses of Dune Plant Communities to Continental Uplift from a Major Earthquake: Sudden Releases from Coastal Squeeze

PubMed Central

Rodil, Iván F.; Jaramillo, Eduardo; Hubbard, David M.; Dugan, Jenifer E.; Melnick, Daniel; Velasquez, Carlos

2015-01-01

Vegetated dunes are recognized as important natural barriers that shelter inland ecosystems and coastlines suffering daily erosive impacts of the sea and extreme events, such as tsunamis. However, societal responses to erosion and shoreline retreat often result in man-made coastal defence structures that cover part of the intertidal and upper shore zones causing coastal squeeze and habitat loss, especially for upper shore biota, such as dune plants. Coseismic uplift of up to 2.0 m on the Peninsula de Arauco (South central Chile, ca. 37.5º S) caused by the 2010 Maule earthquake drastically modified the coastal landscape, including major increases in the width of uplifted beaches and the immediate conversion of mid to low sandy intertidal habitat to supralittoral sandy habitat above the reach of average tides and waves. To investigate the early stage responses in species richness, cover and across-shore distribution of the hitherto absent dune plants, we surveyed two formerly intertidal armoured sites and a nearby intertidal unarmoured site on a sandy beach located on the uplifted coast of Llico (Peninsula de Arauco) over two years. Almost 2 years after the 2010 earthquake, dune plants began to recruit, then rapidly grew and produced dune hummocks in the new upper beach habitats created by uplift at the three sites. Initial vegetation responses were very similar among sites. However, over the course of the study, the emerging vegetated dunes of the armoured sites suffered a slowdown in the development of the spatial distribution process, and remained impoverished in species richness and cover compared to the unarmoured site. Our results suggest that when released from the effects of coastal squeeze, vegetated dunes can recover without restoration actions. However, subsequent human activities and management of newly created beach and dune habitats can significantly alter the trajectory of vegetated dune development. Management that integrates the effects of natural and human induced disturbances, and promotes the development of dune vegetation as natural barriers can provide societal and conservation benefits in coastal ecosystems. PMID:25946057

Latest Holocene Mapping of Tsunamigenically- and Seismogenically-Influenced Beach, Dune and Fluvial Landforms at Tolowa Dunes State Park, Northwestern California

NASA Astrophysics Data System (ADS)

Vaughan, P. R.

2015-12-01

Beach, dune, fluvial, and marine terrace deposits comprise a 16 kilometer (km) coastal strip immediately south of the Smith River at Tolowa Dunes State Park (TDSP), ~ 3.5 km north-northwest from downtown Crescent City, California. The park has numerous Native American sites that are vulnerable to sea level rise and coastal erosion, part of which may be influenced by Cascadia interseismic deformation. Efforts at removal of exotic beach grass (Ammophila arenaria) that stabilizes most of the dune complex have begun; vegetation removal will remobilize the dunes and could obscure and also expose near surficial geologic features. Using a LiDAR base to capture extant data and give context to future resource protection projects, I surficially mapped the dunes and provisionally interpreted, tsunamigenically-derived cobbles (which are more than five feet thick in one road cut exposure) that extensively mantle the deflation plain in the lee of the foredune. Natural, test pit and auger exposures helped characterize fluvial and marsh deposits in the southern bank and floodplain of the Smith River. Optically stimulated luminescence and/or radiocarbon dates constrain the ages for cobble deposits and dunes throughout the park, and liquefaction features exposed in the southern bank of the Smith River. In combination with estimated rates of dune formation and migration at TDSP since the A.D. 1700 Cascadia earthquake, the ages for seismogenically-sourced sediment associated with dune ridges and cobble deposits are tentatively correlated with the ages of latest Holocene Cascadia triggered turbidites dated by Goldfinger et al. (2012) on the Smith River platform. The mapping also helped identify a marine terrace sequence on the southern limb of the northwest-trending Lake Earl Syncline that bifurcates the park, and suggests projection of the northwest-trending Cemetery Scarp, part of the Point St. George fault complex (Polenz and Kelsey 1999), through the southern part of the park.

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

NASA Astrophysics Data System (ADS)

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

2017-12-01

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

Assessing the geomorphic disturbance from fires on coastal dunes near Esperance, Western Australia: Implications for dune de-stabilisation

NASA Astrophysics Data System (ADS)

Shumack, Samuel; Hesse, Paul

2018-04-01

Fire is commonly listed as a contributing disturbance to dune re-activation. This paper aims to characterise post-fire disturbance to vegetation and soil surface, and aeolian activity on coastal dunes. Field data were collected in February 2016 at two sites on coastal dunes near Esperance, Western Australia (WA) after recent wildfires in November 2015 and January 2016. We measured wind profiles at burnt and unburnt sites, and assessed recent sand movement, protective covering and burn severity. We also used remote sensing and on-site photos to monitor local patterns of short term biomass recovery. Results suggest that burnt vegetation enables near surface winds to flow with a similar profile shape to bare surfaces. Speed-up ratios (SR) were higher by 5-120% on burnt surfaces when compared with vegetated. However, burnt vegetation did not show the same topographic acceleration as bare dunes. This decelerating effect correlated with surface-level ground cover after removing topographically sheltered data points (r2 = 0.8, p < 0.001). Burnt surfaces had up to 30% more ripples than vegetated sites, but had significantly fewer ripples than previously-bare surfaces (by 60-100%). This was likely due to ground cover (r2 = 0.95, p < 0.001). Effective ground cover appears to be >40%. At one burnt transect a high burn intensity may have inhibited short term germination and re-sprouting. Fire as the sole disturbance is not a major threat to the stability of these dunes, however, extreme burn intensities may leave dunes susceptible to further non-fire disturbance events.

Changes in Microbial Community Structure and Soil Biological Properties in Mined Dune Areas During Re-vegetation.

PubMed

Escobar, Indra Elena C; Santos, Vilma M; da Silva, Danielle Karla A; Fernandes, Marcelo F; Cavalcante, Uided Maaze T; Maia, Leonor C

2015-06-01

The aim of this study was to describe the impact of re-vegetation on the restoration of microbial community structure and soil microbiological properties in sand dunes that had been affected by mining activity. Soil samples were collected during the dry and rainy seasons from a chronosequence (1, 9, 21 years) of re-vegetated dunes using a single preserved dune as a reference. The composition of the fatty acid methyl esters and soil microbial properties were evaluated. The results showed that the changes in microbial community structure were related to seasonal variations: biomarkers of Gram-positive bacteria were higher than Gram-negative bacteria during the dry season, showing that this group of organisms is more tolerant to these stressful conditions. The microbial community structure in the natural dune was less affected by seasonal variation compared to the re-vegetated areas, whereas the opposite was observed for microbiological properties. Thus, in general, the proportion of saprobic fungi was higher in the natural dune, whereas Gram-negative bacteria were proportionally more common in the younger areas. Although over time the re-vegetation allows the recovery of the microbial community and the soil functions, these communities and functions are different from those found in the undisturbed areas.

Relationship between vegetation dynamics and dune mobility in an arid transgressive coastal system, Maspalomas, Canary Islands

NASA Astrophysics Data System (ADS)

Hernández-Cordero, Antonio I.; Hernández-Calvento, Luis; Espino, Emma Pérez-Chacón

2015-06-01

This paper explores the relationship between vegetation dynamics and dune mobility in an arid transgressive coastal dune system, specifically the dune field of Maspalomas (Gran Canaria, Canary Islands). The aim is to understand the strategies of colonization and survival that plant communities have developed in slacks that face dune advance. The relationship between plant colonization and dune migration was performed by following Tamarix canariensis and Traganum moquinii plants for several years. Morphological data about each individual as well as the distance of each plant to the dune were measured. A study of the colonization patterns developed by T. moquinii, T. canariensis, Cyperus laevigatus and Launaea arborescens communities was performed by analyzing the evolution of consolidated plant patches and adult plants in relation to the dune advance. This was achieved using digital orthophotos and spatial analysis from geographic information systems. Initiation of plant colonization over transgressive dunes occurs on both wet and dry slacks. The results show that both plant colonization and development of adult plants are largely related to dune mobility. Thus, survival of T. moquinii and T. canariensis plants under dune migration conditions is related to both distance to the dune front and plant height at the moment of burial. Distance from the dune front and plant height increases chance of survival. The dynamics of adult plants is also related to dune displacement rates. Thus, each community has different thresholds of resistance to mobility rates. The T. canariensis community withstands average rates higher than 3 m/year. Its arboreal structure allows this species to grow high enough to resist the advance of the dunes and burial. For the T. moquinii community, the population decreases gradually to eventually disappear when dune mobility rates exceed 4 m/year. The C. laevigatus community develops at dune mobility rates lower than 3 m/year, decreasing its surface area at higher rates. The L. arborescens community endures dune migration rates of at least 1.8 m/year. However, different distances between the dune front and the vegetated area also significant factor, because these can compensate for the effects of displacement rates. Thus, the closer a vegetated area is to a dune front, the lower the rates of displacement must be to produce a greater reduction in the surface vegetation. Plant communities present two patterns of plant colonization to resist burial by sand, one vertical and the other horizontal. The horizontal pattern is employed by C. laevigatus and L. arborescens communities and consists of locating new generations of plants in progressive alignment with the dune front migration. The vertical pattern is employed by the T. canariensis community, and consists of increasing the heights of the plants. The T. moquinii community can utilize both patterns because it reacts positively to some degree of burial since it is located in areas where the dunes reach different heights.

Biological soil crust formation under artificial vegetation effect and its properties in the Mugetan sandy land, northeastern Qinghai-Tibet Plateau

NASA Astrophysics Data System (ADS)

Li, Y. F.; Li, Z. W.; Jia, Y. H.; Zhang, K.

2016-08-01

Mugetan sandy land is an inland desertification area of about 2,065 km2 in the northeastern Qinghai-Tibet Plateau. In the ecological restoration region of the Mugetan sandy land, different crusts have formed under the action of vegetation in three types of sandy soil (i.e. semi-fixed sand dune, fixed sand dune and ancient fixed aeolian sandy soil). The surface sand particle distribution, mineral component and vegetation composition of moving sand dunes and three types of sandy soil were studied in 2010-2014 to analyze the biological crust formation properties in the Mugetan sandy land and the effects of artificial vegetation. Results from this study revealed that artificial vegetation increases the clay content and encourages the development of biological curst. The fine particles (i.e. clay and humus) of the surface layer of the sand dunes increased more than 15% ten years after the artificial vegetation planting, and further increased up to 20% after one hundred years. The interaction of clay, humus, and other fine particles formed the soil aggregate structure. Meanwhile, under the vegetation effect from the microbes, algae, and moss, the sand particles stuck together and a biological crust formed. The interconnection of the partial crusts caused the sand dunes to gradually be fixed as a whole. Maintaining the integrity of the biological crust plays a vital role in fixing the sand under the crust. The precipitation and temperature conditions in the Mugetan sandy land could satisfy the demand of biological crust formation and development. If rational vegetation measures are adopted in the region with moving sand dunes, the lichen-moss-algae biological curst will form after ten years, but it still takes more time for the sand dunes to reach the nutrient enrichment state. If the biological curst is partly broken due to human activities, reasonable closure and restoration measures can shorten the restoration time of the biological crust.

Soil bacterial community responses to revegetation of moving sand dune in semi-arid grassland.

PubMed

Cao, Chengyou; Zhang, Ying; Cui, Zhenbo; Feng, Shuwei; Wang, Tingting; Ren, Qing

2017-08-01

Grasslands in semi-arid Northern China are widely desertified, thus inducing the formation of a large area of moving sand lands. Revegetation of the sandy land is commonly adopted to restore degraded grasslands. The structure of the soil microbial community might dramatically change during degradation and recovery because microorganisms are one of the major drivers of ecological process through their interactions with plants and soil. Assuming that soil properties are the key determinants of the structure of soil bacterial community within the same soil type, whether the vegetation type causes the significant difference in the structure of soil bacterial community during revegetation and restoration of the degraded grasslands remains poorly understood. Our study aimed to (1) investigate the response of soil bacterial communities to the changes during vegetation degradation and recovery and (2) evaluate whether the soil bacterial communities under plantations return to their native state. We detected the shifts in diversities and compositions of the soil bacterial communities and the relative abundance of dominant bacterial taxa by using the high-throughput Illumina MiSeq sequencing technique in an area covered by 32-year-old Caragana microphylla, Artemisia halodendron, Hedysarum fruticosum, Pinus sylvestris var. mongolica, Populus simonii, and Salix gordejevii sand-fixing plantations and in the native community (NC) dominated by elm, and moving sandy dune (MS). We found that the obtained operational taxonomic units by 16S rRNA gene sequencing and diversity index in MS were all significantly lower than those in NC, and the number and composition of dominant genera were significantly different between NC and MS. Interestingly, the compositions of bacterial communities and the dominant genera in different sand-fixation plantations (C. microphylla, A. halodendron, H. fruticosum, P. sylvestris var. mongolica, P. simonii, and S. gordejevii) were all similar to those of the native soil of NC, suggesting that the plantation type and soil properties exhibit a minimal effect on the compositions of soil microbial communities within a continuous landscape. These results revealed that the structure of the soil bacterial community of degraded sandy grassland (even degenerated into a mobile sand dunes) in semi-arid region can be reversibly restored by planting indigenous shrub or semi-shrub plantation on human time scales.

Use of remote sensing techniques to determine the effects of grazing on vegetation cover and dune elevation at assateague island national seashore: Impact of horses

USGS Publications Warehouse

De Stoppelaire, G. H.; Gillespie, T.W.; Brock, J.C.; Tobin, G.A.

2004-01-01

The effects of grazing by feral horses on vegetation and dune topography at Assateague Island National Seashore were investigated using color-infrared imagery, lidar surveys, and field measurements. Five pairs of fenced and unfenced plots (300 m2) established in 1993 on sand flats and small dunes with similar elevation, topography, and vegetation cover were used for this study. Color-infrared imagery from 1998 and field measurements from 2001 indicated that there was a significant difference in vegetation cover between the fenced and unfenced plot-pairs over the study period. Fenced plots contained a higher percentage of vegetation cover that was dominated by American beachgrass (Ammophila breviligulata). Lidar surveys from 1997, 1999, and 2000 showed that there were significant differences in elevation and topography between fenced and unfenced plot-pairs. Fenced plots were, on average, 0.63 m higher than unfenced plots, whereas unfenced plots had generally decreased in elevation after establishment in 1993. Results demonstrate that feral horse grazing has had a significant impact on dune formation and has contributed to the erosion of dunes at Assateague Island. The findings suggest that unless the size of the feral horse population is reduced, grazing will continue to foster unnaturally high rates of dune erosion into the future. In order to maintain the natural processes that historically occurred on barrier islands, much larger fenced exclosures would be required to prevent horse grazing. ?? 2004 Springer Science+Business Media, Inc.

Eolian Modeling System: Predicting Windblown Dust Hazards in Battlefield Environments

DTIC Science & Technology

2011-05-03

journals (N/A for none) Pelletier, J.D., H. Mitasova, R.S. Harmon, and M. Overton, The effects of interdune vegetation changes on eolian dune field...J.D., Controls on the height and spacing of eolian ripples and transverse dunes : A numerical modeling investigation, Geomorphology, 105, 322-333, 2009...R.S. Harmon, and M. Overton, The effects of interdune vegetation changes on eolian dune field evolution: A numerical-modeling case study at Jockey’s

Prehistoric fires and the shaping of colonial transported landscapes in southern California: A paleoenvironmental study at Dune Pond, Santa Barbara County

NASA Astrophysics Data System (ADS)

Ejarque, Ana; Anderson, R. Scott; Simms, Alexander R.; Gentry, Beau J.

2015-03-01

Using a novel combination of paleoecologic proxies including pollen, non-pollen palynomorphs (NPPs), macroscopic charcoal, and Spheroidal Carbonaceous Particles (SCPs), 5000 years of landscape change, fire history and land-use have been reconstructed from Dune Pond, Santa Barbara County, California. The pond was sensitive to Holocene regional climatic variability, showing different phases of lower (4600-3700 cal yr BP, 2100-700 cal yr BP, historical period) and higher (3700-2100 cal yr BP, 700-150 cal yr BP) local moisture availability. During this period the landscape was dominated by a coastal mosaic vegetation including dune mats, coastal scrub and salt marshes on the dunes and backdunes, with chaparral and oak woodland growing in the valley plains and foothills. Fire was intimately linked with such dominating mosaic vegetation, and the combination of wet conditions and the presence of nearby human settlement were a trigger favoring coastal fires for at least two periods: from 3100 to 1500 cal yr BP and from 650 cal yr BP until the 18th century. In both cases fire was an important tool to keep an open coastal landscape attractive to hunting wildlife. Finally, matching this varied range of high-resolution paleoecological proxies with historical records we could characterize the development of colonial transported landscapes following the Euro-American settlement of Santa Barbara. The introduction of livestock grazing by Spanish colonists favored erosive processes and the introduction of fecal-borne parasites in freshwater bodies, negatively impacted salt and brackish coastal marshes, and promoted the invasion of alien grasses and ruderals. This agro-pastoral landscape was consolidated during the American period, with a greater role for cultivation, the development of industrial activities and increased population. Despite negative environmental consequences such as the loss of native habitats, exotic land-uses and plants introduced during the historical period significantly contributed to the configuration of a cultural landscape which forms part of the cultural heritage of California.

Vegetation and substrate properties of aeolian dune fields in the Colorado River corridor, Grand Canyon, Arizona

USGS Publications Warehouse

Draut, Amy E.

2011-01-01

This report summarizes vegetation and substrate properties of aeolian landscapes in the Colorado River corridor through Grand Canyon, Arizona, in Grand Canyon National Park. Characterizing these parameters provides a basis from which to assess future changes in this ecosystem, including the spread of nonnative plant species. Differences are apparent between aeolian dune fields that are downwind of where modern controlled flooding deposits new sandbars (modern-fluvial-sourced dune fields) and those that have received little or no new windblown sand since river regulation began in the 1960s (relict-fluvial-sourced dune fields). The most substantial difference between modern- and relict-fluvial-sourced aeolian dune fields is the greater abundance of biologic soil crust in relict dune fields. These findings can be used with similar investigations in other geomorphic settings in Grand Canyon and elsewhere in the Colorado River corridor to evaluate the health of the Colorado River ecosystem over time.

Short-term changes in mobile dunes at Port Alfred, South Africa

NASA Astrophysics Data System (ADS)

Lubke, Roy A.; Sugden, Jean

1990-03-01

Development along the western beachfront of Port Alfred, which is situated along a sandy shoreline, increased markedly in the 1960s as the coastal town became a popular holiday resort. This development included the removal of coastal vegetation, which resulted in the destabilization of dunes and migration of sand westerly onto the road, West Beach parking lot, and lawns of the cabanas. Sand traps were constructed to collect sand blowing across the dunes over set periods, and the net sand movement along the mobile dune belt was calculated using Hunter's equation. The dunes show an easterly movement of sand at a rate of 3.5 m/yr, which is comparable with figures recorded along other areas of this coastline. Considering the wind regime and amount of sand movement along this coast, it is inappropriate to clear vegetation and develop within the dune region.

Sand incursion into temperate (Lithuania) and tropical (the Bahamas) maritime vegetation: Georadar visualization of target-rich aeolian lithosomes

NASA Astrophysics Data System (ADS)

Buynevich, Ilya V.; Savarese, Michael; Curran, H. Allen; Bitinas, Albertas; Glumac, Bosiljka; Pupienis, Donatas; Kopcznski, Karen; Dobrotin, Nikita; Gnivecki, Perry; Boush, Lisa Park; Damušytė, Aldona

2017-08-01

Interaction of windblown sand with maritime vegetation, either as dune migration or episodic grain transport is a common phenomenon along many sandy coasts. Vegetation introduces antecedent surface roughness, especially when scaled to the landform height, but its role may be concealed if overwhelmed by aeolian incursion and burial. Where field observations and cores lack detail for characterizing this complex process, ground-penetrating radar (GPR) offers continuous visualization of aeolian sequences. Along the Curonian Spit, Lithuania, dune reactivation phases resulted in massive invasion of siliciclastic sand triggered by natural perturbations and land clearance. Massive (>30 m high) dunes entombed mature pine, oak, and alder stands and this process is ongoing. Mid-frequency (200 MHz) georadar surveys reveal landward-dipping lateral accretion surfaces interrupted by high-amplitude point-source anomalies produced by recently buried trees. In tropical regions, dense vegetation and potential for rapid lithification of carbonate sand results in more complex internal structures. Along the windward coast of San Salvador Island, the Bahamas, a massive dune has buried several generations of maritime scrubland, resulting in highly chaotic reflection pattern and high target density. On a nearby Little Exuma Island, numerous reentrants in aeolianites promoted formation of blowouts and incursion of windblown sand 10-25 m into a silver thatch palm forest. High-frequency (800 MHz) GPR images resolve diffractions from trunks and roots buried by > 2 m of oolitic sand. Basal refection morphology helps differentiate the irregular dune/beachrock surface from a smooth palm-frond mat. Aside from detecting and mapping buried vegetation, geophysical images capture its effect on sediment accumulation. This has the potential for differentiating its effect from other discordant structures within dunes (clasts, dissolution voids, trunk molds, burrows, and cultural remains).

Looking inside out: tracing internal moisture and salinity changes in dunes on the west coast of Ireland

NASA Astrophysics Data System (ADS)

Nash, Ciaran; Bourke, Mary

2017-04-01

Coastal sand dune systems are some of the most physically dynamic landscapes; their susceptibility to geomorphic change is rooted in a host of interconnected processes and feedbacks. Soil moisture and salinity are two fundamental environmental variables capable of exerting a geomorphic influence but have not been thoroughly investigated in coastal dunes. In northwest Europe, coastal dunes are predominantly sediment-limited systems with reduced capacities to avoid severe morphological changes arising from storms. Climatic changes over the next century are predicted to manifest in more frequent and intense storms with the potential to enact severe geomorphic change in coastal settings. A lack of data pertaining to internal dune hydrosaline dynamics suggests we are missing part of the bigger picture. We conducted a pilot study of moisture and salinity dynamics within the upper 50 cm of the vadose zone in a vegetated dune system at Golden Strand, Achill Island on the west coast of Ireland. Golden Strand is a roughly 800 m long embayed sandy beach, backed by vegetated dunes that protect a low-lying machair grassland. A study transect was established across this dune-machair system, perpendicular to the shore. Innovative instrumentation in the form of capacitance probes and internal dune thermochrons were deployed to sample at 10 cm depth intervals at a sampling rate of 10 minutes and coupled with on-site rainfall data. Results indicate that dune moisture tracks rainfall inputs up to 30 cm depth. Antecedent moisture at depth was found to influence infiltration of water through the dune profile. Salinity within the study transect decreased with distance from the beach, suggesting that salt spray is the primary salt delivery mechanism in the dune system. We also noted that moisture and salinity below 30 cm depth failed to respond to rainfall events of varying intensities. Relatively constant moisture and salinity were observed at all depths within the machair. Predictions of climatic change for Ireland suggest more intense short-period precipitation events, this may increase infiltration depth. Baseline data collected will prove informative in predicting the response of Irish coastal dunes via changes in vegetation and dune stability.

Exploring elements that influence stewardship in the eastern Lake Ontario dune and wetland area

Treesearch

Diane Kuehn; James Smahol

2010-01-01

Th e Eastern Lake Ontario Dune and Wetland Area (ELODWA) is a 17-mile stretch of sand dunes, wetlands, and woodlands along the eastern shore of Lake Ontario in New York State. Reductions in negative, visitor-caused impacts on the dunes (e.g., trampling of dune vegetation and sand erosion) are thought to be due in part to the extensive visitor education efforts of...

Holocene beach buildup and coastal aeolian sand incursions off the Nile littoral cell

NASA Astrophysics Data System (ADS)

Roskin, Joel; Sivan, Dorit; Shtienberg, Gilad; Porat, Naomi; Bookman, Revital

2017-04-01

Israel's coastal plain is abundant with sand originating from the Nile littoral cell. The inland windblown loose sand has formed 3-6 km wide lobe-like sand and dune fields currently comprised of foredunes, linear and northeasterly facing transverse and parabolic dunes that are currently stabilized by vegetation. This study reviews the architecture and history of the these dune fields aiming to: (a) Date the timings of beach accretion, and sand and dune incursions. (b) Discriminate between natural and human-induced forcing factors of sand mobilization and stabilization in time and space. (c) Present a model of the dunescape development. (d) Assess scenarios of sand transport in the future charcaterized by intense human impact and climate change. Luminescence ages, radiocarbon dates and relative ages from previously published geological and archaeological reports, historical texts, together with new optically stimulated luminescence (OSL) ages and stratigraphic and sedimentological data are analyzed. The deposition, mobilizations and preservation of the sand bodies, initially induced by the decline in sea level rise at 6-4 ka, were later controlled by historic land-use intensity and modern land-use/negligence practices. At 6 ka, beach sand buildup rapidly started. Where aeolianite ridges bordered the coast, pulses of sand with biogenic carbonate grains unconformably draped the ridges and rapidly consolidated into a distinct sandy calcarenite unit. Further east, sand sheets and low dunes partly pedogenized following their incursion, but did not cement. The water retention capacities of the sand sheets enabled the establishment of a sand-stabilizing vegetation cover that probably became an attractive environment for fuel and grazing. The growing Hellenistic-Roman-Byzantine ( 2.4-1.3 ka) populations probably led to increased consumption and massive destruction of sand stabilizing vegetation, enabling sand erodibility and mobilization during winter storms. The sand gradually expanded to the current limits of today's dune fields. The gradual but unsteady post-Byzantine demographic drop enabled reestablishment of natural vegetation and rapid regosol development. This drop occurred differentially along the coast due to governance and land-use practices. We suggest that dune construction mainly evolved around the 19th century from the existing sand sheets and low dunes that intermittently developed since 6-5 ka. Human (Bedouin grazing influx and ethnic settlements) destruction of vegetation, in conjuction with the rapid 19th-20th century population growth made the sand prone to "in situ" transverse and linear dune formation in response to powerful winds further supported by increased storminess at this time. Inland dune mobilization and the artificial establishment of vegetated foredunes along the coast in the 1930's-1940's partly scalped the sand deposits by the coast.

New Orleans, LA, District: Report of the Secretary of the Army on Civil Works Activities for FY 2011

DTIC Science & Technology

2011-01-01

side slopes, and protective vegetation. The sandfill berm slopes from an elevation of 8.5 feet, NGVD, at the toe of the dune 150 feet gulfward to an...and vegetated dune constructive with a geotextile tube core extending the length of Grand Isle’s gulf shore and a jetty to stabilize the western end...of the island at Caminada Pass. The dune has a 10-foot-wide crown at an elevation of 13.5 feet, National Geodetic Vertical Datum (NGVD), 1 on 5

The geomorphology and evolution of aeolian landforms within a river valley in a semi-humid environment: A case study from Mainling Valley, Qinghai-Tibet Plateau

NASA Astrophysics Data System (ADS)

Zhou, Na; Zhang, Chun-Lai; Wu, Xiao-Xu; Wang, Xun-ming; Kang, Li-qiang

2014-11-01

This paper systematically analyzes a valley's aeolian landforms in a semi-humid region and presents a model of its contemporary evolution. Mainling Valley of the Yarlung Zangbo River on the Qinghai-Tibet Plateau was chosen as the case study for the analysis of morphometric characteristics and the evolution sequence of aeolian landforms via field data and remote sensing images. The aeolian landforms were primarily composed of aeolian sand belts on river terraces and dunes (sheets) on hillside slopes. Three types of aeolian sand belts were identified based on their dune types. In type I belts, an erosive air stream combined with relatively high vegetation cover (10%) produced sparsely distributed parabolic dunes with a high variability of dune heights; in type II belts, the continual reworking by the erosive air stream in combination with low vegetation cover (3%) formed more densely distributed barchans and transitional dunes with a moderate variability of dune heights; and in type III belts, the gradual evolution from an erosive sand-laden air stream to a saturated sand-laden air stream in combination with low vegetation cover (2%) produced the densest crescentic dunefields but with the least variability in dune heights. Dune sizes increase, dune shapes become uniform, and dune distribution becomes close from type I to III belts. Lateral linking and merging of the dunes were also observed within the belts. Together this evidence indicates that an evolution sequence may exist. Aeolian dunefields in the belt appear to evolve from embryonic parabolic dunefields to adolescent barchan dunefields and, subsequently, to mature compound crescentic dunefields. As the aeolian sand belt evolves into the mature stage, sand accumulations at the foot of the mountain valley can be steps for sand accumulation on valley-side slopes.

Evidence of Active Dune Sand on the Great Plains in the 19th Century from Accounts of Early Explorers

NASA Astrophysics Data System (ADS)

Muhs, Daniel R.; Holliday, Vance T.

1995-03-01

Eolian sand is extensive over the Great Plains of North America, but is at present mostly stabilized by vegetation. Accounts published by early explorers, however, indicate that at least parts of dune fields in Nebraska, Colorado, Kansas, New Mexico, and Texas were active in the 19th century. Based on an index of dune mobility and a regional tree-ring record, the probable causes for these periods of greater eolian activity are droughts, accompanied by higher temperatures, which greatly lowered the precipitation-to-evapotranspiration ratio and diminished the cover of stabilizing vegetation. In addition, observations by several explorers, and previous historical studies, indicate that rivers upwind of Great Plains dune fields had shallow, braided, sandy channels, as well as intermittent flow in the 19th century. Wide, braided, sandy rivers that were frequently dry would have increased sand supplies to active dune fields. We conclude that dune fields in the Great Plains are extremely sensitive to climate change and that the potential for reactivation of stabilized dunes in the future is high, with or without greenhouse warming.

Overview and history of the Beach Vitex Task Force: an interagency partnership in action

USGS Publications Warehouse

Westbrooks, Randy G.; Brabson, Elizabeth N.

2011-01-01

Beach vitex (Vitex rotundifolia L. f.), a woody vine from Korea, was introduced into the United States as a dune stabilization plant in the mid-1980s. By the mid- to late-1990s, Beach vitex was observed spreading from landscape plantings along the South Carolina coast, crowding out native dune species. In 2003, in response to concerns about possible impacts of the plant on native dune species, as well as loggerhead sea turtle nesting habitat, the South Carolina Beach Vitex Task Force was organized to address the problem. Since that time, the effort to control Beach vitex has expanded to include North Carolina, and more recently, Virginia.

Limited change in dune mobility in response to a large decrease in wind power in semi-arid northern China since the 1970s

USGS Publications Warehouse

Mason, J.A.; Swinehart, J.B.; Lu, H.; Miao, X.; Cha, P.; Zhou, Y.

2008-01-01

The climatic controls on dune mobility, especially the relative importance of wind strength, remain incompletely understood. This is a key research problem in semi-arid northern China, both for interpreting past dune activity as evidence of paleoclimate and for predicting future environmental change. Potential eolian sand transport, which is approximately proportional to wind power above the threshold for sand entrainment, has decreased across much of northern China since the 1970s. Over the same period, effective moisture (ratio of precipitation to potential evapotranspiration) has not changed significantly. This "natural experiment" provides insight on the relative importance of wind power as a control on dune mobility in three dunefields of northern China (Mu Us, Otindag, and Horqin), although poorly understood and potentially large effects of human land use complicate interpretation. Dune forms in these three regions are consistent with sand transport vectors inferred from weather station data, suggesting that wind directions have remained stable and the stations adequately represent winds that shaped the dunes. The predicted effect of weaker winds since the 1970s would be dune stabilization, with lower sand transport rates allowing vegetation cover to expand. Large portions of all three dunefields remained stabilized by vegetation in the 1970s despite high wind power. Since the 1970s, trends in remotely sensed vegetation greenness and change in mobile dune area inferred from sequential Landsat images do indicate widespread dune stabilization in the eastern Mu Us region. On the other hand, expansion of active dunes took place farther west in the Mu Us dunefield and especially in the central Otindag dunefield, with little overall change in two parts of the Horqin dunes. Better ground truth is needed to validate the remote sensing analyses, but results presented here place limits on the relative importance of wind strength as a control on dune mobility in the study areas. High wind power alone does not completely destabilize these dunes. A large decrease in wind power either has little short-term effect on the dunes, or more likely its effect is sufficiently small that it is obscured by human impacts on dune stability in many parts of the study areas. ?? 2008 Elsevier B.V. All rights reserved.

The persistence of large-scale blowouts in largely vegetated coastal dune fields

NASA Astrophysics Data System (ADS)

Delgado-Fernandez, Irene; Smyth, Thomas; Jackson, Derek; Davidson-Arnott, Robin; Smith, Alexander

2016-04-01

Coastal dunes move through natural phases of stability and instability during their evolution, displaying various temporal and spatial patterns across the dune field. Recent observations, however, have shown exceptionally rapid rates of stability through increased vegetative growth. This progressive vegetation colonisation and consequent loss of bare sand on coastal dune systems has been noted worldwide. Percentage reductions in bare sand of as much as 80% within just a few decades can been seen in examples from South Africa, Canada and Brazil as well as coastal dune sites across NW Europe. Despite these dramatic trends towards dune stabilisation, it is not uncommon to find particular examples of large-scale active blowouts and parabolic dunes within largely vegetated coastal dunes. While turbulence and airflow dynamics within features such as blowouts and other dune forms has been studied in detail within recent years, there is a lack of knowledge about what maintains dune mobility at these specific points in otherwise largely stabilized dune fields. This work explores the particular example of the 'Devil's Hole' blowout, Sefton Dunes, NW England. Approximately 300 m long by 100 m wide, its basin is below the water-table which leads to frequent flooding. Sefton Dunes in general have seen a dramatic loss of bare sand since the 1940s. However, and coinciding with this period of dune stabilisation, the 'Devil's Hole' has not only remained active but also grown in size at a rate of 4.5 m year-1 along its main axis. An exploration of factors controlling the maintenance of open bare sand areas at this particular location is examined using a variety of techniques including Computational Fluid Dynamics (CFD) airflow modelling and in situ empirical measurements of (short-term experiments) of wind turbulence and sand transport. Field measurements of wind parameters and transport processes were collected over a 2 week period during October 2015. Twenty three 3D ultrasonic anemometers were deployed at 0.5 m elevations over a grid covering sections of the blowout walls, deflation basin and depositional lobe. A number of high resolution sand traps and wenglor sensors were co-located with anemometers in the walls and basin, and a terrestrial laser scanner was used to collect high-resolution topographic data both before and after the strongest transport event recorded during the study period. Preliminary results indicate significant transport differences in operation at each of the two blow out walls as well as complex interactions between turbulence, superficial moisture content and up-wind sediment sources. This study represents a comprehensive examination of both wind and sediment flux patterns at high spatial and temporal resolution inside a large trough blowout feature; and reveals insights into why such systems are maintained as erosional features for long time periods.

Application of Kite Based Aerial Photography to Resolve Short Term Sediment Exchanges Between a Dissipative Beach and Densely Vegetated Dunes

NASA Astrophysics Data System (ADS)

Conlin, M.; Cohn, N.; Ruggiero, P.

2016-12-01

Sand dunes provide coastal communities critical protection from flooding and erosion, as well as a habitat for a range of species- some threatened or endangered. As such, it is of importance to develop a quantitative understanding of the processes through which these systems evolve at a variety of temporal and spatial scales. During summer 2016, a large field campaign in southwest Washington called the Sandbar-aEolian Dune EXchange EXperiment (SEDEX2) focused on developing a suite of data sets fundamental to improving our understanding of the ways in which beaches and dunes grow during fair weather conditions. As part of this experiment, daily to bi-weekly measurements of upper-beach and vegetated dune morphology were collected by post-processing images acquired using a consumer grade kite-based aerial photography system with low-cost Agisoft Photoscan Structure from Motion (SfM) software. Under the appropriate environmental conditions (e.g., sufficient wind, no precipitation, and minimal fog), kite-based SfM techniques minimize survey effort and time as compared to traditional coastal surveying methods such as RTK DGPS and Terrestrial Laser Scanning (TLS), making this approach ideally suited for frequent surveys of small ( < 5 km2) coastal areas. However, while the dominant grass in the area, A. breviligulta (American Beachgrass), is critical for perturbing the wind field, impacting sediment transport processes, and partially dictating dune morphology, it grows densely and therefore complicates the development of aerial photography derived bare-earth digital elevation models. Here we document daily-to-weekly-scale upper beach and dune evolution using kite-based SfM techniques, focusing particularly on improving the efficacy of this technology both in vegetated areas and over short timescales. Our kite-based SfM approach, validated by concurrent RTK DGPS surveys, TLS scans, and dune vegetation surveys, is allowing us to develop quantitative estimates of the sediment exchange between the back-beach and dunes. Other data collected during SEDEX2 are being utilized to determine the primary drivers of these observed changes.

Demography and monitoring of Welsh's milkweed (Asclepias welshii) at Coral Pink Sand Dunes

Treesearch

Brent C. Palmer; L. Armstrong

2001-01-01

Results are presented of a 12-year monitoring program on the Coral Pink Sand Dunes and Sand Hills populations of the threatened Welsh's milkweed, Asclepias welshii N & P Holmgren. The species is an early sera1 member of the dune flora, colonizing blowouts and advancing with shifting dunes. When an area stabilizes and other vegetation encroaches, A. welshii is...

What is a Dune: Developing AN Automated Approach to Extracting Dunes from Digital Elevation Models

NASA Astrophysics Data System (ADS)

Taylor, H.; DeCuir, C.; Wernette, P. A.; Taube, C.; Eyler, R.; Thopson, S.

2016-12-01

Coastal dunes can absorb storm surge and mitigate inland erosion caused by elevated water levels during a storm. In order to understand how a dune responds to and recovers from a storm, it is important that we can first identify and differentiate the beach and dune from the rest of the landscape. Current literature does not provide a consistent definition of what the dune features (e.g. dune toe, dune crest) are or how they can be extracted. The purpose of this research is to develop enhanced approaches to extracting dunes from a digital elevation model (DEM). Manual delineation, convergence index, least-cost path, relative relief, and vegetation abundance were compared and contrasted on a small area of Padre Island National Seashore (PAIS), Preliminary results indicate that the method used to extract the dune greatly affects our interpretation of how the dune changes. The manual delineation method was time intensive and subjective, while the convergence index approach was useful to easily identify the dune crest through maximum and minimum values. The least-cost path method proved to be time intensive due to data clipping; however, this approach resulted in continuous geomorphic landscape features (e.g. dune toe, dune crest). While the relative relief approach shows the most features in multi resolution, it is difficult to assess the accuracy of the extracted features because extracted features appear as points that can vary widely in their location from one meter to the next. The vegetation approach was greatly impacted by the seasonal and annual fluctuations of growth but is advantageous in historical change studies because it can be used to extract consistent dune formation from historical aerial imagery. Improving our ability to more accurately assess dune response and recovery to a storm will enable coastal managers to more accurately predict how dunes may respond to future climate change scenarios.

Erosion of Coastal Foredunes: A Review on the Effect of Dune Vegetation

DTIC Science & Technology

2017-02-01

intensity, sustainable nature-based coastal protection measures are of growing interest. One of these considered features is coastal dunes, which... protection by sand banks, beaches, and dunes. Coastal Engineering 87:136–146. Hesp, P. 1991. Ecological processes and plant adaptations on coastal dunes...ERDC/CHL CHETN-I-94 February 2017 Approved for public release; distribution is unlimited. Erosion of Coastal Foredunes: A Review on the Effect

UAV-imaging to model growth response of marram grass to sand burial: Implications for coastal dune development

NASA Astrophysics Data System (ADS)

Nolet, Corjan; van Puijenbroek, Marinka; Suomalainen, Juha; Limpens, Juul; Riksen, Michel

2018-04-01

Vegetated coastal dunes have the capacity to keep up with sea-level rise by accumulating and stabilizing wind-blown sand. In Europe, this is attributed to marram grass (Ammophila arenaria), a coastal grass species that combines two unique advantages for dune-building: (1) a very high tolerance to burial by wind-blown sand, and (2) more vigorous growth due to positive feedback to sand burial. However, while these vegetation characteristics have been demonstrated, observational data has not been used to model a function to describe the growth response of Ammophila to sand burial. Studies that model coastal dune development by incorporating positive feedback, as a result, may be hampered by growth functions that are unvalidated against field data. Therefore, this study aims to parameterize an empirical relationship to model the growth response of Ammophila to burial by wind-blown sand. A coastal foredune along a nourished beach in the Netherlands was monitored from April 2015 to April 2016. High-resolution geospatial data was acquired using an Unmanned Aerial Vehicle (UAV). Growth response of Ammophila, expressed by changes in Normalized Difference Vegetation Index (Δ NDVI) and vegetation cover (Δ Cover), is related to a sand burial gradient by fitting a Gaussian function using nonlinear quantile regression. The regression curves indicate an optimal burial rate for Ammophila of 0.31 m of sand per growing season, and suggest (by extrapolation of the data) a maximum burial tolerance for Ammophila between 0.78 (for Δ Cover) and 0.96 m (for Δ NDVI) of sand per growing season. These findings are advantageous to coastal management: maximizing the potential of Ammophila to develop dunes maximizes the potential of coastal dunes to provide coastal safety.

Effects of disturbance on vegetation by sand accretion and erosion across coastal dune habitats on a barrier island

PubMed Central

Miller, Thomas E.

2015-01-01

Coastal geomorphology and vegetation are expected to be particularly sensitive to climate change, because of disturbances caused by sea-level rise and increased storm frequency. Dunes have critical reciprocal interactions with vegetation; dunes create habitats for plants, while plants help to build dunes and promote geomorphological stability. These interactions are also greatly affected by disturbances associated with sand movement, either in accretion (dune building) or in erosion. The magnitude and intensity of disturbances are expected to vary with habitat, from the more exposed and less stable foredunes, to low-lying and flood-prone interdunes, to the protected and older backdunes. Permanent plots were established at three different spatial scales on St George Island, FL, USA, where the vegetation and dune elevation were quantified annually from 2011 to 2013. Change in elevation, either through accretion or erosion, was used as a measure of year-to-year disturbance over the 2 years of the study. At the scale of different dune habitats, foredunes were found to have the greatest disturbance, while interdunes had the least. Elevation and habitat (i.e. foredune, interdune, backdune) were significantly correlated with plant community composition. Generalized linear models conducted within each habitat show that the change in elevation (disturbance) is also significantly correlated with the plant community, but only within foredunes and interdunes. The importance of disturbance in exposed foredunes was expected and was found to be related to an increasing abundance of a dominant species (Uniola paniculata) in eroding areas. The significant effect of disturbance in the relatively stable interdunes was surprising, and may be due to the importance of flooding associated with small changes in elevation in these low-lying areas. Overall, this study documents changes in the plant community associated with elevation, and demonstrates that the foredune and interdune communities are also associated with the responses of specific species to local changes in elevation due to accretion or erosion. PMID:25587195

Earth observation taken by the Expedition 28 crew

NASA Image and Video Library

2011-09-08

ISS028-E-044444 (8 Sept. 2011) --- This image, photographed by an Expedition 28 crew member on the International Space Station, highlights a sand dune field within the Burqin-Haba River-Jimunai Desert near the borders of China, Mongolia, Russia and Kazakhstan. The dune field (approximately 32 kilometers long) is located immediately to the west-northwest of the city of Burqin (not shown), and is part of the Junggar Basin, a region of active petroleum production in northwestern China. The Irtysh River, with associated wetlands and riparian vegetation (appearing grey-green in the image) flows from its headwaters in the Altay Mountains to the east towards Siberia to the west (right to left). Tan sandy linear dunes at center on the south side of the Irtysh River dominate the view. The linear dunes are formed from mobile barchan (crescent-shaped) dunes moving from left to right in this view; the barchans eventually merge to form the large linear dunes some of which reach 50-100 meters in height. Sand moving along the southern edge of the dune field appears to be feeding a southeastern lobe with a separate population of linear dunes (lower right). The Burqin-Haba River-Jimunai Desert area also includes darker gravel covered surfaces that form pavements known locally as gobi. These are somewhat indistinguishable from vegetated areas arresting some of the dunes at the resolution of the image, but tend to be located on the flat regions between the dunes.

Holocene Development and Progression of Aeolian Blowouts on Padre Island National Seashore

NASA Astrophysics Data System (ADS)

Jewell, M. E.; Houser, C.

2012-12-01

Recent evidence suggests that development of dune blowouts along Padre Island National Seashore, Texas, and migration of the parabolic dunes to the backbarrier shoreline are the primary mechanisms by which the island transgresses in response to relative sea level rise. This study characterizes the development and migration of dune blowouts at decadal and century scales in order to understand these changes. An initial breach, caused by the removal of vegetation, develops along the dune line allowing sediment to be funneled into the dune field. The entrance of the blowout focuses the wind velocity, allowing sediment to be transported into the dune field, covering any vegetation that is present. This process continues as sediment is eroded from the foredune increasing the size of the blowout until the foredune is rebuilt and vegetation stabilizes the entrance. With the front stabilized, the blowout begins its movement across the island. Aerial photographs, LIDAR data, ground penetrating radar, and optically stimulated luminescence were used to track and date the migration of these blowouts. Photographs and satellite images, taken at least twice a decade since the 1940s, were used to track blowouts from their initial conception to their final stabilization by vegetation. Each consecutive blowout was digitized to understand the surface characteristics of the feature. For a greater understanding of the system at the decadal scale, LIDAR data collected by the USGS and other agencies was used to create an elevation model in order compute the volumetric changes within the northern portion of the National Seashore. Within the larger study area, three smaller sites: a young blowout that had just begun to close as the foredune is reestablished, a "middle age" blowout that was detached from the foredune and become an active dune field, and a former blowout now stabilized by vegetation, were selected for geophysical analysis . A Trimble GX 3-D scanner was used to determine the current volume of the blowouts and to create an end point for the elevation model at the smaller scale. Then a ground penetrating radar survey was completed at both dune normal and the average direction of travel for each blowout to show the bounding layers, cross stratification, and bedding planes of the migrating blowout without physical disruption. Vibracoring and optically stimulated luminescence provided a physical comparison of the stratigraphy to the data returned in the GPR survey. By using this comparison, sediment type, structures, and burial age are compared to geomorphic properties to determine the abundance of storms, sediment budget, and vegetation extent, which are key characteristics in understanding blowouts. These factors are integral in understanding how the blowouts have changed over the past 70 years and how these variables will affect evolution and spatial distribution of the shoreline.

Deep Soil Recharge in Arid and Semi-Arid Regions: New Evidences in MU-US Sandy Land of China

NASA Astrophysics Data System (ADS)

Cheng, Y.; Yang, W.; Zhan, H.

2017-12-01

Precipitation induced recharge is an important source of groundwater budget but it is very difficult to quantify in arid and semiarid regions. In this study, a newly invented lysimeter was used to monitor deep soil recharge (DSR) under 200 cm depth in MU-US sandy land in western China under three kinds of landforms (mobile dune, semi-fixed dune, and fixed dune). We found that the annual DSRs in such three different kinds of landforms varied significantly. Specifically, the annual DSRs were 224.1 mm (50.5% of the annual precipitation), 71.1 mm (50.5% of the annual precipitation), and 1.3 mm (0.3% of the annual precipitation) in mobile dune, semi-fixed dune, and fixed dune, respectively. We also found that vegetation coverage and precipitation pattern significantly affected DSR. A 24-hr precipitation event with the precipitation amount greater than 8 mm was able to infiltrate soil deeper than 200 cm and contributed to ground water recharge directly. Vegetation was a dominant factor influencing infiltration in the fixed sand dune. Our research revealed that precipitation induced DSR in arid and semi-arid regions was a complex process that required long-term monitoring and innovative system analysis of interrelated factors such as precipitation strength and pattern, meteorological parameters, and dynamic soil moisture. Key words: Precipitation pattern, sand dune groundwater, deep soil recharge, infiltration.

Relations between Vegetation and Geologic Framework in Barrier Island

NASA Astrophysics Data System (ADS)

Smart, N. H.; Ferguson, J. B.; Lehner, J. D.; Taylor, D.; Tuttle, L. F., II; Wernette, P. A.

2017-12-01

Barrier islands provide valuable ecosystems and protective services to coastal communities. The longevity of barrier islands is threatened by sea-level rise, human impacts, and extreme storms. The purpose of this research is to evaluate how vegetation dynamics interact with the subsurface and offshore framework geology to influence the beach and dune morphology. Beach and dune morphology can be viewed as free and/or forced behavior, where free systems are stochastic and the morphology is dependent on variations in the storm surge run-up, aeolian sediment supply and transport potential, and vegetation dynamics and persistence. Forced systems are those where patterns in the coastal morphology are determined by some other structural control, such as the underlying and offshore framework geology. Previous studies have documented the effects of geologic framework or vegetation dynamics on the beach and dunes, although none have examined possible control by vegetation dynamics in context of the geologic framework (i.e. combined free and forced behavior). Padre Island National Seashore (PAIS) was used to examine the interaction of free and forced morphology because the subsurface framework geology and surface beach and dune morphology are variable along the island. Vegetation dynamics were assessed by classifying geographically referenced historical aerial imagery into areas with vegetation and areas without vegetation, as well as LiDAR data to verify this imagery. The subsurface geologic structure was assessed using a combination of geophysical surveys (i.e. electromagnetic induction, ground-penetrating radar, and offshore seismic surveys). Comparison of the observed vegetation patterns and geologic framework leads to a series of questions surrounding how mechanistically these two drivers of coastal morphology are related. Upcoming coring and geophysical surveys will enable us to validate new and existing geophysical data. Results of this paper will help us better understand how barrier islands have responded to environmental change in the past should be integrated into current models of barrier island evolution in order to more accurately predict how the island will change over time in response to continued climatic variability.

Quantification of Dune Response over the Course of a 6-Day Nor'Easter, Outer Banks, NC

NASA Astrophysics Data System (ADS)

Brodie, K. L.; Spore, N.; Swann, C.

2014-12-01

The amount and type of foredune morphologic change during a storm event primarily scales with the level of inundation during that event. Specifically, external hydrodynamic forcing (total water level) can be compared with antecedent beach and foredune morphology to predict an impact regime that relates to the type of expected morphologic evolution of the system. For example, when total water levels are above the dune toe, but below the dune crest, the impact regime is classified as "collision" and the expected morphology response is slumping or scarping of the dune face. While the amount of dune retreat scales largely with the duration of wave attack to the dune face, characteristics of the dune other than its crest or toe elevation may also enhance or impede rates of morphologic change. The aftermath of Hurricane Sandy provided a unique opportunity to observe alongshore variations in dune response to a 6-day Nor'Easter (Hs >4 m in 6 m depth), as a variety of dunes were constructed (or not) by individual home owners in preparation for the winter storm season. Daily terrestrial lidar scans were conducted along 20 km of coastline in Duck, NC using Coastal Lidar And Radar Imaging System (CLARIS) during the first dune collision event following Sandy. Foredunes were grouped by their pre-storm form (e.g. vegetated, pushed, scarped, etc) using automated feature extraction tools based on surface curvature and slope, and daily rates of morphologic volume change were calculated. The highest dune retreat rates were focused along a 1.5 km region where cross-shore erosion of recently pushed, un-vegetated dunes reached 2 m/day. Variations in dune response were analyzed in relation to their pre-storm morphology, with care taken to normalize for alongshore variations in hydrodynamic forcing. Ongoing research is focused on identifying specific metrics that can be easily extracted from topographic DEMs to aid in dune retreat predictions.

Erosion Control and Environment Restoration Plan Development, Matagorda County, Texas. Phase 2. Preliminary Design

DTIC Science & Technology

2013-08-01

recommended groin system. ......................... 37  Figure 23. H1% and Hs at the groin toe as a function of storm surge...phases of work. Keep in mind, the recommended groin system design will advance the shoreline; however, without dune and vegetation management, it...will not create a wider dry beach. Since the existing beach is presumably in equili- brium, the dune and vegetation will advance with the shoreline

Effects of sedimentation on soil physical and chemical properties and vegetation characteristics in sand dunes at the Southern Dongting Lake region, China

PubMed Central

Pan, Ying; Zhang, Hao; Li, Xu; Xie, Yonghong

2016-01-01

Sedimentation is recognized as a major factor determining the ecosystem processes of lake beaches; however, the underlying mechanisms, especially in freshwater sand dunes, have been insufficiently studied. To this end, nine belt transects from nine freshwater sand dunes, classified into low (<23.7 m), medium (25.4–26.0 m), and high-elevation groups (>28.1 m) based on their elevations in 1972, were sampled to investigate differences in sedimentation rate and soil and vegetation characteristics in Southern Dongting Lake, China. Sedimentation rate, soil sand content, and soil pH increased, whereas soil clay, fine silt, moisture (MC), organic matter (OM), total N, and total K content, in addition to the growth and biodiversity of sand dune plants generally decreased with decreasing belt transect elevation. Regression analyses revealed that the negative effects of sedimentation on the ecosystem functions of sand dunes could be attributed to higher fine sand content in deposited sediments and stronger inhibition of plant growth. These results are consistent with previous studies performed in coastal sand dunes, which highlights the importance of sedimentation in determining ecological processes. PMID:27808154

Effects of sedimentation on soil physical and chemical properties and vegetation characteristics in sand dunes at the Southern Dongting Lake region, China

NASA Astrophysics Data System (ADS)

Pan, Ying; Zhang, Hao; Li, Xu; Xie, Yonghong

2016-11-01

Sedimentation is recognized as a major factor determining the ecosystem processes of lake beaches; however, the underlying mechanisms, especially in freshwater sand dunes, have been insufficiently studied. To this end, nine belt transects from nine freshwater sand dunes, classified into low (<23.7 m), medium (25.4-26.0 m), and high-elevation groups (>28.1 m) based on their elevations in 1972, were sampled to investigate differences in sedimentation rate and soil and vegetation characteristics in Southern Dongting Lake, China. Sedimentation rate, soil sand content, and soil pH increased, whereas soil clay, fine silt, moisture (MC), organic matter (OM), total N, and total K content, in addition to the growth and biodiversity of sand dune plants generally decreased with decreasing belt transect elevation. Regression analyses revealed that the negative effects of sedimentation on the ecosystem functions of sand dunes could be attributed to higher fine sand content in deposited sediments and stronger inhibition of plant growth. These results are consistent with previous studies performed in coastal sand dunes, which highlights the importance of sedimentation in determining ecological processes.

Municipal initiatives for managing dunes in coastal residential areas: a case study of Avalon, New Jersey, USA

NASA Astrophysics Data System (ADS)

Nordstrom, Karl F.; Jackson, Nancy L.; Bruno, Michael S.; de Butts, Harry A.

2002-10-01

The characteristics of foredunes created in a municipal management program on a developed barrier island are evaluated to identify how landforms used as protection structures can be natural in appearance and function yet compatible with human values. Shoreline management zones include a naturally evolving, undeveloped segment; a noneroding, developed segment; eroding and noneroding segments of an "improved beach" where dunes have been built by artificial nourishment; and a privately built, artificially nourished dune on the shoreline of an inlet. A disastrous storm in 1962 resulted in an aggressive program for building dunes using sand fences, vegetation plantings, purchase of undeveloped lots, and sediment backpassing to maintain beach widths and dune elevations. The present nourished and shaped foredune in the improved beach is higher, wider, and closer to the berm crest than the natural dune. Restricted inputs of aeolian sand keep the surface flat and poorly vegetated. A stable section of this engineered shore has a wider beach, and sand fences have created a higher foredune with greater topographic diversity. The cross shore zonation of vegetation here is more typical of natural dunes, but the environmental gradient is much narrower. The privately built dune is low, narrow, and located where it could not be created naturally. Foreshore and aeolian sediments in the undeveloped segment and the improved beach are similar in mean grain size (0.16-0.21 mm) and sorting (0.31-0.39 φ), but sediment on the surface of the nourished dune is coarser (28.1% gravel) with a more poorly sorted sand fraction (1.30 φ) representing lag elements on the deflation surface. Willingness to enhance beaches and dunes for protection has reduced insurance premiums and allowed the municipality to qualify for funds from the Federal Emergency Management Agency (FEMA) to replace lost sediment, thus placing an economic value on dunes. Success of the management program is attributed to: (i) timing property-purchase and dune-building programs to periods immediately after storms (causing residents to accept high dunes that restrict access or views); (ii) instituting a vigorous education program (reminding residents of hazards during nonstorm periods); (iii) maintaining control over local sediment supplies (to keep pace with erosion and create new shoreline environments); (iv) investing private and municipal economic resources in landforms (qualifying them for external funds for replacement); and (v) maintaining, augmenting, or simply tolerating biodiversity and natural processes (retaining a natural heritage).

Responses of woody species to spatial and temporal ground water changes in coastal sand dune systems

NASA Astrophysics Data System (ADS)

Máguas, C.; Rascher, K. G.; Martins-Loução, A.; Carvalho, P.; Pinho, P.; Ramos, M.; Correia, O.; Werner, C.

2011-02-01

In spite of the relative importance of groundwater in coastal dune systems, the number of studies concerning the responsiveness of vegetation to ground water (GW) variability, in particularly in Mediterranean regions, is scarce. In this study, we established 5 study sites within a meso-mediterranean sand dune Pinus pinaster forest on the Atlantic coast of Portugal, taking advantage of natural topographic variability and artificial GW exploitation, which resulted in substantial variability in depth to GW between microsites. Here we identify the degree of usage and dependence on GW of different plant functional groups (two deep-rooted trees, a drought adapted shrub, a phreatophyte and a non-native woody invader) and how GW dependence varied seasonally and between the heterogeneous microsites. Our results indicated that the plant species had differential responses to changes in GW depth according to specific functional traits (i.e. rooting depth, leaf morphology, and water use strategy). The species comparison revealed that variability in pre-dawn water potential (Ψpre) and bulk leaf δ13C was related to microsite differences in GW use in deep-rooted (Pinus pinaster, Myrica faya) and phreatophyte (Salix repens) species. However, such variation was more evident during spring rather than during summer drought. The exotic invader, Acacia longifolia, which does not possess a very deep root system, presented the largest seasonal variability in Ψpre and bulk leaf δ13C. In contrast, the response of Corema album, an endemic understorey drought adapted shrub, across seasons and microsites seemed to be independent of water availability. Thus, the susceptibility to changing GW availability in sand dune plant species is variable, being particularly relevant for deep rooted species and phreatophytes, which have typically been less exposed to GW fluctuations.

Responses of woody species to spatial and temporal ground water changes in coastal sand dune systems

NASA Astrophysics Data System (ADS)

Máguas, C.; Rascher, K. G.; Martins-Loução, A.; Carvalho, P.; Pinho, P.; Ramos, M.; Correia, O.; Werner, C.

2011-12-01

In spite of the relative importance of groundwater in costal dune systems, studies concerning the responses of vegetation to ground water (GW) availability variations, particularly in Mediterranean regions, are scarce. Thus, the main purpose of this study is to compare the responses of co-occurring species possessing different functional traits, to changes in GW levels (i.e. the lowering of GW levels) in a sand dune ecosystem. For that, five sites were established within a 1 km2 area in a meso-mediterranean sand dune ecosystem dominated by a Pinus pinaster forest. Due to natural topographic variability and anthropogenic GW exploitation, substantial variability in depth to GW between sites was found. Under these conditions it was possible to identify the degree of usage and dependence on GW of different plant species (two deep-rooted trees, a drought adapted shrub, a phreatophyte and a non-native woody invader) and how GW dependence varied seasonally and between the heterogeneous sites. Results indicated that the plant species had differential responses to changes in GW depth according to specific functional traits (i.e. rooting depth, leaf morphology, and water use strategy). Species comparison revealed that variability in pre-dawn water potential (Ψpre) and bulk leaf δ13C was related to site differences in GW use in the deep-rooted (Pinus pinaster, Myrica faya) and phreatophyte (Salix repens) species. However, such variation was more evident during spring than during summer drought. The exotic invader, Acacia longifolia, which does not possess a very deep root system, presented the largest seasonal variability in Ψpre and bulk leaf δ13C. In contrast, the response of Corema album, an endemic understory drought-adapted shrub, seemed to be independent of water availability across seasons and sites. Thus, the susceptibility to lowering of GW due to anthropogenic exploitation, in plant species from sand dunes, is variable, being particularly relevant for deep rooted species and phreatophytes, which seem to depend heavily on access to GW.

Using Large-Scale Roughness Elements to Control Sand and Dust Flux at the Keeler Dunes, Keeler, CA

NASA Astrophysics Data System (ADS)

Gillies, John; McCarley-Holder, Grace

2014-05-01

Controlling dust emission from areas that subsequently degrade air quality and threaten human and animal health and reduce the quality of life for people residing in proximity to such sources is necessary, but also challenging. Recent research has indicated that arrays of large roughness elements (height >0.3 m) can be used effectively to modulate sand transport and the associated dust emissions. Prediction of the rate of sand flux reduction as a function of downwind distance upon entering an array of roughness elements, and the equilibrium flux reduction in the interior of the array is possible using the known geometric properties of the roughness elements, their number, and published relationships. Air quality in the town of Keeler, CA (36 deg 29' 17.92" N, 117 deg 52' 24.62" W) is degraded by levels of particulate matter <10 µm aerodynamic diameter (PM10) during periods of elevated wind speeds due to sand transport and dust emissions in the nearby Keeler Dunes. A demonstration project was designed to evaluate the effectiveness of an array of roughness elements composed of solid elements and managed vegetation to meet sand and dust flux reduction criteria. This project has two major goals: 1) to demonstrate that solid roughness elements placed on areas of the Keeler Dunes immediately arrest sand movement to specified levels (target of 85% reduction), and 2) to assess whether native plant species, planted in the sheltered area of the solid roughness elements can effectively thrive and subsequently replace the solid roughness to achieve the desired sand flux reduction control efficiency. This poster describes the results related mostly to objective one, as considerable time has to pass before sufficient data will be obtained to evaluate the success of the planted and managed vegetation to achieve a control level provided by the solid element roughness array.

Effects of disturbance on vegetation by sand accretion and erosion across coastal dune habitats on a barrier island.

PubMed

Miller, Thomas E

2015-01-12

Coastal geomorphology and vegetation are expected to be particularly sensitive to climate change, because of disturbances caused by sea-level rise and increased storm frequency. Dunes have critical reciprocal interactions with vegetation; dunes create habitats for plants, while plants help to build dunes and promote geomorphological stability. These interactions are also greatly affected by disturbances associated with sand movement, either in accretion (dune building) or in erosion. The magnitude and intensity of disturbances are expected to vary with habitat, from the more exposed and less stable foredunes, to low-lying and flood-prone interdunes, to the protected and older backdunes. Permanent plots were established at three different spatial scales on St George Island, FL, USA, where the vegetation and dune elevation were quantified annually from 2011 to 2013. Change in elevation, either through accretion or erosion, was used as a measure of year-to-year disturbance over the 2 years of the study. At the scale of different dune habitats, foredunes were found to have the greatest disturbance, while interdunes had the least. Elevation and habitat (i.e. foredune, interdune, backdune) were significantly correlated with plant community composition. Generalized linear models conducted within each habitat show that the change in elevation (disturbance) is also significantly correlated with the plant community, but only within foredunes and interdunes. The importance of disturbance in exposed foredunes was expected and was found to be related to an increasing abundance of a dominant species (Uniola paniculata) in eroding areas. The significant effect of disturbance in the relatively stable interdunes was surprising, and may be due to the importance of flooding associated with small changes in elevation in these low-lying areas. Overall, this study documents changes in the plant community associated with elevation, and demonstrates that the foredune and interdune communities are also associated with the responses of specific species to local changes in elevation due to accretion or erosion. Published by Oxford University Press on behalf of the Annals of Botany Company.

Optically stimulated luminescence dating of aeolian sand in the otindag dune field and holocene climate change

USGS Publications Warehouse

Zhou, Y.L.; Lu, H.Y.; Mason, J.; Miao, X.D.; Swinehart, J.; Goble, R.

2008-01-01

The dune system in Otindag sand field of northern China is sensitive to climate change, where effective moisture and related vegetation cover play a controlling role for dune activity and stability. Therefore, aeolian deposits may be an archive of past environmental changes, possibly at the millennial scale, but previous studies on this topic have rarely been reported. In this study, thirty-five optically stimulated luminescence (OSL) ages of ten representative sand-paleosol profiles in Otindag sand field are obtained, and these ages provide a relatively complete and well-dated chronology for wet and dry variations in Holocene. The results indicate that widespread dune mobilization occurred from 9.9 to 8.2 ka, suggesting a dry early Holocene climate. The dunes were mainly stabilized between 8.0 and 2.7 ka, implying a relatively wet climate, although there were short-term penetrations of dune activity during this wet period. After ???2.3 ka, the region became dry again, as inferred from widespread dune activity. The "8.2 ka" cold event and the Little Ice Age climatic deterioration are detected on the basis of the dune records and OSL ages. During the Medieval Warm Period and the Sui-Tang Warm Period (570-770 AD), climate in Otindag sand field was relatively humid and the vegetation was denser, and the sand dunes were stabilized again. These aeolian records may indicate climate changes at millennial time scale during Holocene, and these climatic changes may be the teleconnection to the climate changes elsewhere in the world. ?? Science in China Press and Springer-Verlag GmbH 2008.

Vegetation controls on the maximum size of coastal dunes.

PubMed

Durán, Orencio; Moore, Laura J

2013-10-22

Coastal dunes, in particular foredunes, support a resilient ecosystem and reduce coastal vulnerability to storms. In contrast to dry desert dunes, coastal dunes arise from interactions between biological and physical processes. Ecologists have traditionally addressed coastal ecosystems by assuming that they adapt to preexisting dune topography, whereas geomorphologists have studied the properties of foredunes primarily in connection to physical, not biological, factors. Here, we study foredune development using an ecomorphodynamic model that resolves the coevolution of topography and vegetation in response to both physical and ecological factors. We find that foredune growth is eventually limited by a negative feedback between wind flow and topography. As a consequence, steady-state foredunes are scale invariant, which allows us to derive scaling relations for maximum foredune height and formation time. These relations suggest that plant zonation (in particular for strand "dune-building" species) is the primary factor controlling the maximum size of foredunes and therefore the amount of sand stored in a coastal dune system. We also find that aeolian sand supply to the dunes determines the timescale of foredune formation. These results offer a potential explanation for the empirical relation between beach type and foredune size, in which large (small) foredunes are found on dissipative (reflective) beaches. Higher waves associated with dissipative beaches increase the disturbance of strand species, which shifts foredune formation landward and thus leads to larger foredunes. In this scenario, plants play a much more active role in modifying their habitat and altering coastal vulnerability than previously thought.

Unique Microbial Phylotypes in Namib Desert Dune and Gravel Plain Fairy Circle Soils.

PubMed

van der Walt, Andries J; Johnson, Riegardt M; Cowan, Don A; Seely, Mary; Ramond, Jean-Baptiste

2016-08-01

Fairy circles (FCs) are barren circular patches of soil surrounded by grass species. Their origin is poorly understood. FCs feature in both the gravel plains and the dune fields of the Namib Desert. While a substantial number of hypotheses to explain the origin and/or maintenance of fairy circles have been presented, none are completely consistent with either their properties or their distribution. In this study, we investigated the hypothesis that FC formation in dunes and gravel plains is due to microbial phytopathogenesis. Surface soils from five gravel plain and five dune FCs, together with control soil samples, were analyzed using high-throughput sequencing of bacterial/archaeal (16S rRNA gene) and fungal (internal transcribed spacer [ITS] region) phylogenetic markers. Our analyses showed that gravel plain and dune FC microbial communities are phylogenetically distinct and that FC communities differ from those of adjacent vegetated soils. Furthermore, various soil physicochemical properties, particularly the pH, the Ca, P, Na, and SO4 contents, the soil particle size, and the percentage of carbon, significantly influenced the compositions of dune and gravel plain FC microbial communities, but none were found to segregate FC and vegetated soil communities. Nevertheless, 9 bacterial, 1 archaeal, and 57 fungal phylotypes were identified as FC specific, since they were present within the gravel plain and dune FC soils only, not in the vegetated soils. Some of these FC-specific phylotypes were assigned to taxa known to harbor phytopathogenic microorganisms. This suggests that these FC-specific microbial taxa may be involved in the formation and/or maintenance of Namib Desert FCs. Fairy circles (FCs) are mysterious barren circular patches of soil found within a grass matrix in the dune fields and gravel plains of the Namib Desert. Various hypotheses attempting to explain this phenomenon have been proposed. To date, however, none have been successful in fully explaining the etiology of FCs, particularly since gravel plain FCs have been largely ignored. In this study, we investigated the hypothesis that microorganisms could be involved in the FC phenomenon through phytopathogenesis. We show that the microbial communities in FC and control vegetated soil samples were significantly different. Furthermore, we detected 67 FC-specific microbial phylotypes, i.e., phylotypes present solely in both gravel plain and dune FC soils, some of which were closely related to known phytopathogens. Our results, therefore, demonstrate that microorganisms may play a role in the formation and/or maintenance of Namib Desert FCs, possibly via phytopathogenic activities. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

RPAS Monitoring of the Morphological Evolution of Coastal Foredunes

NASA Astrophysics Data System (ADS)

Taddia, Yuri; Corbau, Corinne; Elena, Zambello; Russo, Valentina; Pellegrinelli, Alberto; Simeoni, Umberto

2016-04-01

The coastal environment is in rapid and continuous evolution and it is easily affected by many natural and antropic factors. Beaches are often backed by vegetated dunes and fulfill many different valuable ecosystem functions. They act as protective buffers against storm surge, wave attack and erosion, providing a unique habitat for flora and fauna. Coastal embryo dunes, found above mean high water, are dynamic landform being able to supply sand to the beach when needed. They may form rapidly and may be rapidly destructed due to high tides and storm waves or human interferences. The southern part (3 km long) of Rosolina (Adriatic Sea, Italy) is characterized by a wide beach bordered by a complex dune system. The geomorphological characteristics of embryo dunes have been identified by using an RPAS in order to develop a fast and low-cost surveying technique. The aircraft has flown at a 50 meters altitude, taking photos with a 12Mpix RGB camera and a GSD of about 1 cm. The images overlap of 80% in the flight direction and 60% laterally. Fourteen targets have been collocated in the area as ground control points and were surveyed using Network Real Time Kinematic (NRTK) GNSS. Images and GCPs were elaborated in Agisoft PhotoScan to generate the model. A similar NRTK survey has been performed to integrate the wrong data (due to vegetation) for the creation of a digital elevation model (DEM) in a first step and finally to validate the model obtained through UAV photogrammetry through a comparison with specially surveyed points. The creation of a DEM from photos is one of main tasks and its accuracy is critical. A challenge in this work was to recognize the vegetation in the sand dunes area to exclude all the points not belonging to the ground. This was possible through a classification process based on slope detection. Finally, the suitable elevation accuracy has been reached and the survey has revealed a complex dune system characterized by: • on the upper part of the beach (about 1.50 meter amsl), isolated embryo dunes (incipient foredunes) and foredunes develop along a cross-shore section of about 30 meters; • a "depresssive" interdune of about 10 meters; • a second field of successive well-developed dunes. The first foredunes are of small dimensions (about 0.50 m height), and are aligned to the prevailing wind directions. The second field of dunes are higher (about 1 meter height) and form a "continuous" dune ridge parallel to the shoreline. Another significant advantage of this method is the possibility to obtain information on the vegetation, which is an important factor driving the evolution of coastal dunes. Different blowouts and pathways have been also mapped. The use of the orthophoto will therefore allow to collect simultaneously physical and biological data and consequently to analyze their interaction in order to improve the management of the coastal dune systems. This study exhibits how RPAS can be successfully used in representing the spatial distribution of embryo coastal dunes and in monitoring their development.

Effects of a non-native biocontrol weevil, Larinus planus, and other emerging threats on populations of the federally threatened Pitcher's thistle, Cirsium pitcheri

USGS Publications Warehouse

Havens, Kayri; Jolls, Claudia L.; Marik, Julie E.; Vitt, Pati; McEachern, A. Kathryn; Kind, Darcy

2012-01-01

Larinus planus Frabicius (Curculionidae), is a seed-eating weevil that was inadvertently introduced into the US and was subsequently distributed in the US and Canada for the control of noxious thistle species of rangelands. It has been detected recently in the federally threatened Pitcher's thistle (Cirsium pitcheri). We assayed weevil damage in a natural population of Pitcher's thistle at Whitefish Dunes State Park, Door County, WI and quantified the impact on fecundity. We then estimated the impact of this introduced weevil and other emerging threats on two natural, uninvaded populations of Pitcher's thistle for which we have long-term demographic data for 16 yr (Wilderness State Park, Emmet County, MI) and 23 yr (Miller High Dunes, Indiana Dunes National Lakeshore, Porter County, IN). We used transition matrices to determine growth rates and project the potential effects of weevil damage, inbreeding, goldfinch predation, and vegetative succession on Pitcher's thistle population viability. Based on our models, weevil seed predation reduced population growth rate by 10–12%, but this reduction was enough to reduce time to extinction from 24 yr to 13 yr and 8 yr to 5 yr in the MI and IN population, respectively. This impact is particularly severe, given most populations of Pitcher's thistle throughout its range hover near or below replacement. This is the first report of unanticipated ecological impacts from a biocontrol agent on natural populations of Cirsium pitcheri.

Barchan and Linear Dunes on Earth and Mars - Comparative Research

NASA Astrophysics Data System (ADS)

Tsoar, H.; Edgett, K. S.; Schatz, V.; Parteli, E. J.; Herrmann, H. J.

2007-05-01

High resolution images from MGS and MRO reveal, in detail, ripples and dunes on Mars that were not discerned in old Viking images. The two basic dune types known on Earth, barchan (and transverse) and seif (linear), are also common on Mars, although seif dunes are quite rare on that planet. Some Martian barchan and seif dunes have a different morphology, particularly as evident in the Martian north polar region. Some of the barchans have an elongated, elliptical shape, while some of the linear dunes lack the sinuosity commonly associated with terrestrial seif dunes. These barchan and linear dunes occur together, side-by-side, and in some cases are merged to create a single bed-form. Induration of the dunes, or crust formation, can explain the occurrence of these dunes of unusual morphology in the Martian north polar region. Crusts may form as water vapor diffuses into and out of the fine-grained materials on the planet's surface. Salts would be deposited as intergranular cement. Because these bedforms occur in the polar region, the cementing agent could be ice instead of salts; indeed, the dunes spend more than half each Martian year beneath a covering of seasonal frost, mostly frozen carbon dioxide. Elliptical shaped barchans were created artificially in Saudi Arabia by spraying advancing barchan dunes with crude oil to stabilize them until the dunes reached a streamlined body shape. Simulation work indicates that the same process can occur on the indurated Martian barchans, but by cementation of grains rather than introduction of oil. Short lee dunes that have a linear shape with a sharp-edged crest are known to form from sand accumulation at the lee side of obstacles. Once a dune is stabilized by induration or crust, it functions as an obstacle to the wind. Linear lee dunes stabilized by ice (water or carbon dioxide) or mineral crust may elongate and form a long linear dune that aligns parallel to the wind. Melting of the ice will set up a straight linear dune, with loose sand, parallel to the dominant wind. Field observations on terrestrial deserts show that such a dune can only be formed when it is covered by vegetation. If vegetation is removed the bare linear dune disintegrates into small barchans. Simulation also shows that linear dune is unstable and deforms until it takes the shape of a string of barchans, which are the stable shape under unidirectional winds.

A comparison of seed banks across a sand dune successional gradient at Lake Michigan dunes (Indiana, USA)

USGS Publications Warehouse

Leicht-Young, S. A.; Pavlovic, N.B.; Grundel, R.; Frohnapple, K.J.

2009-01-01

In habitats where disturbance is frequent, seed banks are important for the regeneration of vegetation. Sand dune systems are dynamic habitats in which sand movement provides intermittent disturbance. As succession proceeds from bare sand to forest, the disturbance decreases. At Indiana Dunes National Lakeshore, we examined the seed banks of three habitat types across a successional gradient: foredunes, secondary dunes, and oak savanna. There were differences among the types of species that germinated from each of the habitats. The mean seed bank density increased across the successional gradient by habitat, from 376 to 433 to 968 seeds m-2, but with foredune and secondary dune seed bank densities being significantly lower than the savanna seed bank density. The number of seeds germinated was significantly correlated with soil organic carbon, demonstrating for this primary successional sequence that seed density increases with stage and age. The seed bank had much lower species richness than that of the aboveground vegetation across all habitats. Among sites within a habitat type, the similarity of species germinated from the seed banks was very low, illustrating the variability of the seed bank even in similar habitat types. These results suggest that restoration of these habitats cannot rely on seed banks alone. ?? 2008 Springer Science+Business Media B.V.

Biological soil crust as a bio-mediator alters hydrological processes in stabilized dune system of the Tengger Desert, China

NASA Astrophysics Data System (ADS)

Li, Xinrong

2016-04-01

Biological soil crust (BSC) is a vital component in the stabilized sand dunes with a living cover up to more than 70% of the total, which has been considered as a bio-mediator that directly influences and regulates the sand dune ecosystem processes. However, its influences on soil hydrological processes have been long neglected in Chinese deserts. In this study, BSCs of different successional stages were chose to test their influence on the hydrological processes of stabilized dune, where the groundwater deep exceeds 30m, further to explore why occur the sand-binding vegetation replacement between shrubs and herbs. Our long-term observation (60 years) shows that cyanobacteria crust has been colonized and developed after 3 years since the sand-binding vegetation has been established and dune fixation using planted xerophytic shrubs and made sand barrier (straw-checkerboard) on shifting dune surface, lichen and moss crust occurred after 20 years, and the cover of moss dominated crust could reach 70 % after 50 years. The colonization and development of BSC altered the initial soil water balance of revegetated areas by influencing rainfall infiltration, soil evaporation and dew water entrapment. The results show that BSC obviously reduced the infiltration that occurred during most rainfall events (80%), when rainfall was greater than 5 mm or less than 20 mm. The presence of BSC reduced evaporation of topsoil after small rainfall (<5 mm) because its high proportion of finer particles slowed the evaporation rate, thus keeping the water in the soil surface longer, and crust facilitated topsoil evaporation when rainfall reached 10 mm. The amount of dew entrapment increases with the succession of BSC. Moreover, the effect of the later successional BSC to dew entrapment, rainfall infiltration and evaporation was more obvious than the early successional BSC on stabilized dunes. In general, BSC reduced the amount of rainfall water that reached deeper soil (0.4-3m), which is where the roots of shrubs are primarily distributed. These changes in the soil moisture pattern induced shifting of sand-binding vegetation from initial planted xerophytic shrub communities with higher coverage (35%) to complex communities dominated by shallow-rooted herbaceous species with low shrub coverage (9%). In correspondence with these changes, soil water balance of the initial vegetation systems (mean soil water kept 3.5%) was turned into a new balance of current vegetation (mean soil water maintains 1.5%). Above findings provide an important enlightenment for future desertification control and sand hazards prevention by revegetation.

Effects of Trampling Limitation on Coastal Dune Plant Communities

NASA Astrophysics Data System (ADS)

Santoro, Riccardo; Jucker, Tommaso; Prisco, Irene; Carboni, Marta; Battisti, Corrado; Acosta, Alicia T. R.

2012-03-01

Sandy coastlines are sensitive ecosystems where human activities can have considerable negative impacts. In particular, trampling by beach visitors is a disturbance that affects dune vegetation both at the species and community level. In this study we assess the effects of the limitation of human trampling on dune vegetation in a coastal protected area of Central Italy. We compare plant species diversity in two recently fenced sectors with that of an unfenced area (and therefore subject to human trampling) using rarefaction curves and a diversity/dominance approach during a two year study period. Our results indicate that limiting human trampling seems to be a key factor in driving changes in the plant diversity of dune systems. In 2007 the regression lines of species abundance as a function of rank showed steep slopes and high Y-intercept values in all sectors, indicating a comparable level of stress and dominance across the entire study site. On the contrary, in 2009 the regression lines of the two fenced sectors clearly diverge from that of the open sector, showing less steep slopes. This change in the slopes of the tendency lines, evidenced by the diversity/dominance diagrams and related to an increase in species diversity, suggests the recovery of plant communities in the two fences between 2007 and 2009. In general, plant communities subject to trampling tended to be poorer in species and less structured, since only dominant and tolerant plant species persisted. Furthermore, limiting trampling appears to have produced positive changes in the dune vegetation assemblage after a period of only two years. These results are encouraging for the management of coastal dune systems. They highlight how a simple and cost-effective management strategy, based on passive recovery conservation measures (i.e., fence building), can be a quick (1-2 years) and effective method for improving and safeguarding the diversity of dune plant communities.

Multiple origins of linear dunes on Earth and Titan

USGS Publications Warehouse

Rubin, David M.; Hesp, Patrick A.

2009-01-01

Dunes with relatively long and parallel crests are classified as linear dunes. On Earth, they form in at least two environmental settings: where winds of bimodal direction blow across loose sand, and also where single-direction winds blow over sediment that is locally stabilized, be it through vegetation, sediment cohesion or topographic shelter from the winds. Linear dunes have also been identified on Titan, where they are thought to form in loose sand. Here we present evidence that in the Qaidam Basin, China, linear dunes are found downwind of transverse dunes owing to higher cohesiveness in the downwind sediments, which contain larger amounts of salt and mud. We also present a compilation of other settings where sediment stabilization has been reported to produce linear dunes. We suggest that in this dune-forming process, loose sediment accumulates on the dunes and is stabilized; the stable dune then functions as a topographic shelter, which induces the deposition of sediments downwind. We conclude that a model in which Titan's dunes formed similarly in cohesive sediments cannot be ruled out by the existing data.

Mineralogic variability of the Kelso Dunes, Mojave Desert, California derived from Thermal Infrared Multispectral Scanner (TIMS) data

NASA Technical Reports Server (NTRS)

Ramsey, Michael S.; Howard, Douglas A.; Christensen, Philip R.; Lancaster, Nicholas

1993-01-01

Mineral identification and mapping of alluvial material using thermal infrared (TIR) remote sensing is extremely useful for tracking sediment transport, assessing the degree of weathering and locating sediment sources. As a result of the linear relation between a mineral's percentage in a given area (image pixel) and the depth of its diagnostic spectral features, TIR spectra can be deconvolved in order to ascertain mineralogic percentages. Typical complications such as vegetation, particle size and thermal shadowing are minimized upon examination of dunes. Actively saltating dunes contain little to no vegetation, are very well sorted and lack the thermal shadows that arise from rocky terrain. The primary focus of this work was to use the Kelso Dunes as a test location for an accuracy analysis of temperature/emissivity separation and linear unmixing algorithms. Accurate determination of ground temperature and component discrimination will become key products of future ASTER data. A decorrelation stretch of the TIMS image showed clear color variations within the active dunes. Samples collected from these color units were analyzed for mineralogy, grain size, and separated into endmembers. This analysis not only revealed that the dunes contained significant mineralogic variation, but were more immature (low quartz percentage) than previously reported. Unmixing of the TIMS data using the primary mineral endmembers produced unique variations within the dunes and may indicate near, rather than far, source locales for the dunes. The Kelso Dunes lie in the eastern Mojave Desert, California, approximately 95 km west of the Colorado River. The primary dune field is contained within a topographic basin bounded by the Providence, Granite Mountains, with the active region marked by three northeast trending linear ridges. Although active, the dunes appear to lie at an opposing regional wind boundary which produces little net movement of the crests. Previous studies have estimated the dunes range from 70% to 90% quartz mainly derived from a source 40 km to the west. The dune field is assumed to have formed in a much more arid climate than present, with the age of the deposit estimated at greater than 100,000 years.

Conceptual Model Development for Sea Turtle Nesting Habitat: Support for USACE Navigation Projects

DTIC Science & Technology

2015-08-01

regional values. • Beach Width: The width of the beach (m) defines the region from the shoreline to the dune toe . Loggerhead turtles tend to prefer...primary drivers of the model parameters. • Beach Elevation: Beach elevation (m) is measured from the shoreline to the dune toe . Elevation influences...mapping, and morphological features in combination with imagery-derived environmental parameters (i.e., dune vegetation) have not been attempted

A data driven model for dune morphodynamics

NASA Astrophysics Data System (ADS)

Palmsten, M.; Brodie, K.; Spore, N.

2016-12-01

Dune morphology results from a number of competing feedbacks between wave, Aeolian, and biologic processes. Only now are conceptual and numerical models for dunes beginning to incorporate all aspects of the processes driving morphodynamics. Drawing on a 35-year record of observations of dune morphology and forcing conditions at the Army Corps of Engineers Field Research Facility (FRF) at Duck, NC, USA, we hypothesize that local dune morphology results from the competition between dune growth during dry windy periods and erosion during storms. We test our hypothesis by developing a data driven model using a Bayesian network to hindcast dune-crest elevation change, dune position change, and shoreline position change. Model inputs include a description of dune morphology from dune-crest elevation, dune-base elevation, dune width, and beach width. Wave forcing and the effect of moisture is parameterized in terms of the maximum total water level and period that waves impact the dunes, along with precipitation. Aeolian forcing is parameterized in terms of maximum wind speed, direction and period that wind exceeds a critical value for sediment transport. We test the sensitivity of our model to forcing parameters and hindcast the 35-year record of dune morphodynamics at the FRF. We also discuss the role of vegetation on dune morphologic differences observed at the FRF.

Mediterranean dunes on the go: Evidence from a short term study on coastal herbaceous vegetation

NASA Astrophysics Data System (ADS)

Prisco, Irene; Stanisci, Angela; Acosta, Alicia T. R.

2016-12-01

Detailed monitoring studies on permanent sites are a promising tool for an accurate evaluation of short, medium or long term vegetation dynamics. This work aims to evaluate short-term changes in coastal dune herbaceous plant species and EU Habitats through a multi-temporal analysis using permanent vegetation transects. In particular, (I) we analyze changes in species richness of coastal habitats; (II) we identify changes in plant cover of selected focal plants; and (III) we relate the changes to selected climatic variables and erosion/accretion processes. We selected one of the Italian's peninsula best preserved coastal dune areas (ca. 50 km along the Adriatic sea) with a relatively homogeneous coastal zonation and low anthropic pressure but with different erosion/accretion processes. We explored changes in richness over time using generalized linear models (GLMs). We identified different ecological guilds: focal, ruderal and alien plant species and investigated temporal trends in these guilds' species richness. We also applied GLMs to determine how plant cover of the most important focal species have changed over time. Overall, in this study we observed that the influence of climatic variables was relatively small. However, we found remarkable different trends in response to erosion/accretion processes both at community and at species level. Thus, our results highlight the importance of coastal dynamics in preserving not only coastal vegetation zonation, but also species richness and focal species cover. Moreover, we identified the dune grasslands as the most sensitive habitat for detecting the influence of climatic variables throughout a short term monitoring survey. Information from this study provides useful insights for detecting changes in vegetation, for establishing habitat protection priorities and for improving conservation efforts for these fragile ecosystems.

Quantifying the effects of European beach grass on aeolian sand transport over the last century: Bodega Marine Reserve, California

NASA Astrophysics Data System (ADS)

Cesmat, R.; Werner, S.; Smith, M. E.; Riedel, T.; Best, R.; Olyarnik, S.

2012-12-01

Introduction of European beach grass (Ammophila arenaria) to coastal dune systems of western North America induced significant changes to the transport and storage of sediment, and consequently the nesting habitat of the western snowy plover (Charadrius alexandrinus nivosus). At the Bodega Marine Reserve and Sonoma Coast State Park, Ammophila was introduced within the ~0.5 km2 dune area in the 1920's to limit the flux of sand through Bodega Harbor and agricultural land. To assess the potential impact of restoration efforts (Ammophila removal) on aeolian sediment flux, we measured sediment flux as a function of wind speeds and ground cover, and used these measurements to parameterize a spatial model for historical sand deposition Fine- to coarse-grained lithic to sub-lithic sand is delivered to the Bodega dune system from Salmon Creek beach, the down-shore terminus of a littoral system fed by the 3846 km2 Russian River catchment, several small (<100 km2) coastal catchments, and seacliff erosion. Littoral sediment traverses the 1.8 km wide dune system from NW to SE via aeolian transport. Ammophila colonization occurred initially adjacent to the shoreface, inducing deposition of a ~10 meter-high foredune and has subsequently encroached the ~0.5 km2 region between the foredune and Bodega Harbor. Comparison of historical topographic maps via raster subtraction indicates rapid construction of both the foredune and a ~15 meter-high transverse dune (Gaffney ridge) at the edge of the planted region. An average accumulation rate of ~4,000 m3/yr is indicated within the study swath by the preserved sediment volumes. Within the modern dune system, unvegetated areas exhibit 2-3 meter wavelength, ~1/2 meter amplitude mega-ripples, and the uppermost 2-10 cm consists of coarse-sand to granule-sized armor layer. In contrast, grain-sizes in vegetated areas are largely vertically homogenous. Open areas are typically 2-8 meters lower than adjacent vegetated areas, and show evidence for net lowering of the land surface (i.e., exposed fence posts, roots). Conversely, vegetated areas appear prone to sediment accumulation, particularly downwind of unvegetated areas. We measured sand transport using 0.5 m high traps deployed at 18 sites throughout the dune field, and used a linear mixed effects model to predict transport rate as a function of wind and ground cover class, taking into account random effects of sampling date and repeated measurements at each site. The analysis indicates up to 450-times higher transport rates in unvegetated areas relative to vegetated areas at peak wind conditions. We then used these results to parameterize a simple raster-based sediment flux model for the 0.5 km wide study area, using LIDAR-based topography and aerial orthophotography to classify ground cover. Due to the nearly complete compartmentalization of sediment flux by vegetative baffling, the model suggests that proposed restoration (removal of vegetative cover) of the seaward 1 km of the dune system would lead to significant increases in sediment transport in the treated area accompanied by accumulation along its vegetated downwind edge, but little to no change in sand flux within Ammophila-covered areas >0.2 km downwind of restored areas.

KSC-04pd1632

NASA Image and Video Library

2004-07-08

KENNEDY SPACE CENTER, FLA. - The calm blue ocean near the launch pads at KSC beckons. The sand dunes facing the Atlantic Ocean spill pink flowers down its banks. The vegetation helps prevent the dunes from eroding. The beach is part of the Canaveral National Seashore, managed by the National Wildlife Service.

Heterogeneous environments shape invader impacts: integrating environmental, structural and functional effects by isoscapes and remote sensing.

PubMed

Hellmann, Christine; Große-Stoltenberg, André; Thiele, Jan; Oldeland, Jens; Werner, Christiane

2017-06-23

Spatial heterogeneity of ecosystems crucially influences plant performance, while in return plant feedbacks on their environment may increase heterogeneous patterns. This is of particular relevance for exotic plant invaders that transform native ecosystems, yet, approaches integrating geospatial information of environmental heterogeneity and plant-plant interaction are lacking. Here, we combined remotely sensed information of site topography and vegetation cover with a functional tracer of the N cycle, δ 15 N. Based on the case study of the invasion of an N 2 -fixing acacia in a nutrient-poor dune ecosystem, we present the first model that can successfully predict (R 2  = 0.6) small-scale spatial variation of foliar δ 15 N in a non-fixing native species from observed geospatial data. Thereby, the generalized additive mixed model revealed modulating effects of heterogeneous environments on invader impacts. Hence, linking remote sensing techniques with tracers of biological processes will advance our understanding of the dynamics and functioning of spatially structured heterogeneous systems from small to large spatial scales.

Type characters of non-native plant species in Great Lakes national parks (USA)

USGS Publications Warehouse

Bennett, J.P.; Brundu, G.; Brock, J.; Camarda, I.; Child, L.; Wade, M.

2001-01-01

Non-native plant species are increasing in frequency and abundance in many natural areas in the United States. In Midwestern National Parks, as much as one third of the flora may be non-native. It was hypothesized that botanical characters of these species could be used to typify them and improve the methods of predicting invasions. Data on 19 characters of 341 non-native species from the four Great Lakes national lakeshores (Apostle Islands, Indiana Dunes, Pictured Rocks, and Sleeping Bear Dunes) and invasive non-native species for the State of Wisconsin were collected and studied. For many of the species, little data could be found, but for 139 of them, data were collected for at least 80% of the characters. The frequencies of classes of the characters were tabulated and ranked to typify the most common non-native species. This led to a description of a 'type species' just for these four National Parks. Three species of Cirsium, including Canada (C. arvense), marsh (C. palustre) and bull thistle (C. vulgare), matched the type species better than other species. C. vulgare occurs in more National Parks than the other thistles.

Megadroughts and late Holocene dune activation at the eastern margin of the Great Plains, north-central Kansas, USA

NASA Astrophysics Data System (ADS)

Hanson, P. R.; Arbogast, A. F.; Johnson, W. C.; Joeckel, R. M.; Young, A. R.

2010-01-01

Optical and radiocarbon dating indicates that alluvium underlying dunes near Abilene was deposited at or before ˜45 ka, and that the overlying dunes were active at ˜1.1-0.5 ka. Geochemical data indicate that the Abilene dune sand is immature and was derived from the underlying Pleistocene alluvium, and not from Holocene age Smoky Hill River deposits. These findings suggest that dune activation was a response to increased aridity and local reduction in vegetation cover as opposed to changes in sediment availability from nearby rivers. The time interval of dune activation at Abilene overlaps Medieval Warm Period megadroughts, similar to the larger and more westerly dune fields on the Great Plains, including the Nebraska Sand Hills and the Great Bend Sand Prairie. The activation of smaller dune fields such as the Abilene dunes near the more humid eastern margin of the Great Plains shows the geographic extent and severity of paleodrought events. Unlike the Duncan dunes, another plains-marginal dune field, however, the Abilene dunes show no evidence for multiple drought events during the Holocene. This difference in dune activity, if it is not a result of sampling or preservation bias, indicates variations in the extent and severity of older drought events at the eastern margin of the Great Plains.

Patterns of woody plant invasion in an Argentinean coastal grassland

NASA Astrophysics Data System (ADS)

Alberio, Constanza; Comparatore, Viviana

2014-01-01

Coastal dune grasslands are fragile ecosystems that have historically been subjected to various types of uses and human activities. In Buenos Aires Province (Argentina), these areas are frequently afforested for urban and touristic development. The introduction and subsequent spread of exotic tree species is one of the main threats to conservation of natural grasslands as invasive trees strongly transform their structure and composition. The aim of this study was to identify patterns of woody plant invasion comparing plant communities and environmental variables between invaded and non-invaded areas surrounding the coastal village of Mar Azul, Argentina. Coastal grasslands in this area are being invaded by Populus alba (white poplar) and Acacia longifolia (coast wattle). The height of the saplings and the richness of the accompanying vegetation were evaluated in relation to the distance from the edge of the mature tree patches. Also, the cover, richness and diversity of all species in the invaded and non-invaded areas were measured, as well as soil pH, temperature and particle size. Negative correlations were found between the height of the saplings and distance to mature tree patches in all areas. The richness of the accompanying vegetation was negatively and positively correlated with the distance from the poplar and acacia area, respectively. The most abundant native species was Cortaderia selloana. Less cover, richness and diversity of native plant species and greater soil particle size were found in invaded areas, where the proportion of bare soil was higher. Also, a higher proportion of leaf litter in the invaded areas was registered. The results emphasize the invasive capacity of P. alba and A. longifolia advancing on the native communities and reducing their richness. Knowledge of the impact of invasive woody plants in coastal grasslands is important to design active management strategies for conservation purposes.

Banded vegetation-dune development during the Medieval Warm Period and 20th century, Chihuahuan Desert, New Mexico, USA

USDA-ARS?s Scientific Manuscript database

With the advent of systematic high-resolution satellite photography, striking geometric shapes of banded vegetation several km2 in size, but not apparent from the ground, have been documented for many areas of the arid and semiarid world. Banded vegetation, in which dense perennial vegetation altern...

Automated mapping of linear dunefield morphometric parameters from remotely-sensed data

NASA Astrophysics Data System (ADS)

Telfer, M. W.; Fyfe, R. M.; Lewin, S.

2015-12-01

Linear dunes are among the world's most common desert dune types, and typically occur in dunefields arranged in remarkably organized patterns extending over hundreds of kilometers. The causes of the patterns, formed by dunes merging, bifurcating and terminating, are still poorly understood, although it is widely accepted that they are emergent properties of the complex system of interactions between the boundary layer and an often-vegetated erodible substrate. Where such dunefields are vegetated, they are typically used as extensive rangeland, yet it is evident that many currently stabilized dunefields have been reactivated repeatedly during the late Quaternary. It has been suggested that dunefield patterning and the temporal evolution of dunefields are related, and thus there is considerable interest in better understanding the boundary conditions controlling dune patterning, especially given the possibility of reactivation of currently-stabilized dunefields under 21st century climate change. However, the time-consuming process of manual dune mapping has hampered attempts at quantitative description of dunefield patterning. This study aims to develop and test methods for delineating linear dune trendlines automatically from freely-available remotely sensed datasets. The highest resolution free global topographic data presently available (Aster GDEM v2) proved to be of marginal use, as the topographic expression of the dunes is of the same order as the vertical precision of the dataset (∼10 m), but in regions with relatively simple patterning it defined dune trends adequately. Analysis of spectral data (panchromatic Landsat 8 data) proved more promising in five of the six test sites, and despite poor panchromatic signal/noise ratios for the sixth site, the reflectance in the deep blue/violet (Landsat 8 Band 1) offers an alternative method of delineating dune pattern. A new edge detection algorithm (LInear Dune Optimized edge detection; LIDO) is proposed, based on Sobel operators with directional filtering and topologically-constrained recursion to optimize the inclusion of marginal zones. The method offers the potential for rapid quantitative mapping of linear dunefield patterning, providing validation data for modeling studies, and offering for the first time the ability to readily remap dunefields to assess dune reorganization at the dunefield scale.

Mobile dune fixation by a fast-growing clonal plant: a full life-cycle analysis.

PubMed

Li, Shou-Li; Yu, Fei-Hai; Werger, Marinus J A; Dong, Ming; During, Heinjo J; Zuidema, Pieter A

2015-03-11

Desertification is a global environmental problem, and arid dunes with sparse vegetation are especially vulnerable to desertification. One way to combat desertification is to increase vegetation cover by planting plant species that can realize fast population expansion, even in harsh environments. To evaluate the success of planted species and provide guidance for selecting proper species to stabilize active dunes, demographic studies in natural habitats are essential. We studied the life history traits and population dynamics of a dominant clonal shrub Hedysarum laeve in Inner-Mongolia, northern China. Vital rates of 19057 ramets were recorded during three annual censuses (2007-2009) and used to parameterize Integral Projection Models to analyse population dynamics. The life history of H. laeve was characterized by high ramet turnover and population recruitment entirely depended on clonal propagation. Stochastic population growth rate was 1.32, suggesting that the populations were experiencing rapid expansion. Elasticity analysis revealed that clonal propagation was the key contributor to population growth. The capacity of high clonal propagation and rapid population expansion in mobile dunes makes H. laeve a suitable species to combat desertification. Species with similar life-history traits to H. laeve are likely to offer good opportunities for stabilizing active dunes in arid inland ecosystems.

Holocene dune formation at Ash Meadows National Wildlife Area, Nevada, USA

USGS Publications Warehouse

Lancaster, Nicholas; Mahan, Shannon

2012-01-01

Small isolated dune fields in the northern Mojave Desert are important centers of biodiversity and archaeological occupation sites. Currently dunes at Ash Meadows, Nevada, are stabilized by vegetation and are experiencing erosion of their upwind margins, indicating a negative sediment budget. New OSL ages from dunes at Ash Meadows indicate continuous eolian accumulation from 1.5 to 0.8 ka, with further accumulation around 0.2 ka. Prior studies (e.g., Mehringer and Warren, 1976) indicate periods of dune accumulation prior to 3.3 ka; 1.9–1 ka; and after 0.9 ka. These periods of eolian accumulation are largely synchronous with those identified elsewhere in the Mojave Desert. The composition of the Ash Meadows dunes indicates their derivation from regional fluvial sources, most likely during periods when axial washes were active as a result of enhanced winter precipitation.

Alluvial Fans on Dunes in Kaiser Crater Suggest Niveo-Aeolian and Denivation Processes on Mars

NASA Technical Reports Server (NTRS)

Bourke, M. C.

2005-01-01

On Earth, cold region sand dunes often contain inter-bedded sand, snow, and ice. These mixed deposits of wind-driven snow, sand, silt, vegetal debris, or other detritus have been termed Niveo-aeolian deposits. These deposits are often coupled with features that are due to melting or sublimation of snow, called denivation features. Snow and ice may be incorporated into dunes on Mars in three ways. Diffusion of water vapour into pore spaces is the widely accepted mechanism for the accretion of premafrost ice. Additional mechanisms may include the burial by sand of snow that has fallen on the dune surface or the synchronous transportation and deposition of snow, sand and ice. Both of these mechanisms have been reported for polar dunes on Earth. Niveo-aeolian deposits in polar deserts on Earth have unique morphologies and sedimentary structures that are generally not found in warm desert dunes. Recent analysis of MOC-scale data have found evidence for potential niveo-aeolian and denivation deposits in sand dunes on Mars.

Foredune morphodynamics and seasonal sediment budget patterns at Humboldt Bay, Arcata, California.

NASA Astrophysics Data System (ADS)

Rader, A. M.; Walker, I. J.; Pickart, A.; Bauer, B. O.; Hesp, P.

2017-12-01

Coastal dune erosion, rebuilding, and ecosystem restoration are examined along a dune barrier system at Humboldt Bay, Arcata California. The long-term evolution of the system indicates progradation in the north (up to +0.51 m a-1) with densely vegetated, tall and topographically simple foredunes and landward retreat in the south (up to -0.49 m a-1) with sparsely vegetated, hummocky foredunes and blowouts. Spatial-temporal patterns of change from seasonal bare-Earth models during the early stages of a dynamic restoration project indicate that, in the year following initial removal of invasive vegetation (May 2015 - September 2016), the foredune system experienced a net positive sediment budget (+0.54 m3 m-2) while net erosion occurred on the beach (-0.38 m3 m-2). Five years of cross-shore profiles show a seaward migration of the foredune crest (+0.15 m mo-1) during the same time period. However, net erosion of the beach occurred during winter (November 2015 - April 2016), due to high-water and wave run-up during intense storms. Summer monitoring reveals site-wide accretion due to beach rebuilding and increased aeolian activity. As such, seasonal sediment budgets may be controlled primarily by the amount of beach sediment available for aeolian transport and secondarily by localized vegetation zonation on the upper beach and foredune. Further monitoring of the dune barrier system at Humboldt Bay throughout the remaining dynamic restoration process will provide further insight into the role of vegetation zonation and foredune morphodynamics.

Parabolic dune reactivation and migration at Napeague, NY, USA: Insights from aerial and GPR imagery

NASA Astrophysics Data System (ADS)

Girardi, James D.; Davis, Dan M.

2010-02-01

Observations from mapping since the 19th century and aerial imagery since 1930 have been used to study changes in the aeolian geomorphology of coastal parabolic dunes over the last ~ 170 years in the Walking Dune Field, Napeague, NY. The five large parabolic dunes of the Walking Dune Field have all migrated across, or are presently interacting with, a variably forested area that has affected their migration, stabilization and morphology. This study has concentrated on a dune with a particularly complex history of stabilization, reactivation and migration. We have correlated that dune's surface evolution, as revealed by aerial imagery, with its internal structures imaged using 200 MHz and 500 MHz Ground Penetrating Radar (GPR) surveys. Both 2D (transect) and high-resolution 3D GPR imagery image downwind dipping bedding planes which can be grouped by apparent dip angle into several discrete packages of beds that reflect distinct decadal-scale episodes of dune reactivation and growth. From aerial and high resolution GPR imagery, we document a unique mode of reactivation and migration linked to upwind dune formation and parabolic dune interactions with forest trees. This study documents how dune-dune and dune-vegetation interactions have influenced a unique mode of blowout deposition that has alternated on a decadal scale between opposite sides of a parabolic dune during reactivation and migration. The pattern of recent parabolic dune reactivation and migration in the Walking Dune Field appears to be somewhat more complex, and perhaps more sensitive to subtle environmental pressures, than an idealized growth model with uniform deposition and purely on-axis migration. This pattern, believed to be prevalent among other parabolic dunes in the Walking Dune Field, may occur also in many other places where similar observational constraints are unavailable.

75 FR 6364 - Process for Requesting a Variance From Vegetation Standards for Levees and Floodwalls

Federal Register 2010, 2011, 2012, 2013, 2014

2010-02-09

..., channels, or shore- line or river-bank protection systems such as revetments, sand dunes, and barrier...) toe (subject to preexisting right-of-way). f. The vegetation variance process is not a mechanism to...

Past and future of the EU-habitat directive species Liparis loeselii in relation to landscape and habitat dynamics in SW-Texel, the Netherlands.

PubMed

Kooijman, A M; Bruin, C J W; van de Craats, A; Grootjans, A P; Oostermeijer, J G B; Scholten, R; Sharudin, R

2016-10-15

Dune slacks are important habitats, with many endangered plant species. A series of eleven dune slacks of 1-42years old was studied in SW-Texel, the Netherlands, with the EU-habitat directive species Liparis loeselii present in all except the youngest and oldest. Analysis of aerial photographs revealed that new slacks are currently formed every 4-5years. In each slack, topsoil and vegetation data were collected in 2010 and 2014-2015. During succession, vegetation changed from brackish pioneer stages to dune slacks with L. loeselii and Parnassia palustris and ultimately grassland species. Differences between dune slacks and sampling periods were mostly significant. Herb cover and soil C increased with slack age, and over the five year study period, while bare sand, bulk density and pH decreased. The annual pH-decrease was 0.055 and 0.075 for pH-H2O and pH-KCl respectively, and annual C-increase 0.16% and 35gm(-2). Liparis loeselii was only present between pHH2O 5.8-7.5 and pHKCl 5.6-7.6, and only occurred at C-content below 4.3%. In lime-poor dunes, environmental conditions thus become unsuitable approximately 34years after the start of succession. In the dune slacks, Liparis loeselii established within 6years, showed peak values after 11-16years, and declined until conditions became unsuitable. Rejuvenation may occur after large storms with fresh sand deposits. However, even with further succession, the present populations are not endangered and probably last until 2040. With new dune slacks every 5years, L. loeselii occurs in approximately eight different dune slacks at the same time, ensuring viable populations also in the future. This shows that adverse effects of succession can be counteracted by dynamics on local and landscape scale. Copyright © 2016 Elsevier B.V. All rights reserved.

Late Holocene dune mobilizations in the northwestern Negev dunefield, Israel: A response to combined anthropogenic activity and short-term intensified windiness

NASA Astrophysics Data System (ADS)

Roskin, Joel; Katra, Itzhak; Blumberg, Dan G.

2013-04-01

The study of the effects of past climates on ancient cultures is usually based on geologic records pertaining to rainfall and temperature fluctuations and shifts. This study proposes a paradigm of anthropogenic activity and windiness fluctuations to explain aeolian sedimentation and dune mobilization in the northwestern (NW) Negev Desert dunefield (Israel). The proposed paradigm contributes a different approach to estimating the effect of climate changes on the unprecedented agricultural and urban settlement expansion during the late Roman to Early Islamic period in the northern and central Negev Desert. This study builds upon the late Holocene cluster of luminescence ages of Roskin et al. (Age, origin and climatic controls on vegetated linear dunes in the northwestern Negev Desert (Israel), Quaternary Science Reviews 30 (2011), 1649-1674) coupled with analysis of archaeological finds and historical texts. We suggest that whereas the NW Negev dunefield was generally stable during the Holocene, intermittent dune mobilization during the late Holocene, at ~1.8 ka and mostly 1.4-1.1 ka (~600-900 CE), are linked to periods of human occupation. The idea that the last glacial dune encroachments alone that formed the NW Negev dunefield is connected to cold-event windy climates that may have intensified East Mediterranean cyclonic winter storms, cannot explain the late Holocene dune mobilizations. We conceptually model a connection between late Holocene dune mobilization, widespread anthropogenic occupation and activity, and windiness. We maintain that historic grazing and uprooting shrubs for fuel in the past by nomads and sedentary populations led to decimation of dune stabilizers, biogenic soil crusts and vegetation, causing dune erodibility and low-grade activity. Short-term events of amplified wind power in conjunction with periods of augmented anthropogenic activity that triggered major events of dune mobilization (elongation) and accretion have been preserved in the dune chronostratigraphy. Because they were short lived, the dune mobilization events, corresponding windiness, and probable dustiness which were examined affected the northern Negev landscape differentially. However, they cannot be proved to have affected the environment sufficiently to influence the decline of the late Byzantine and Early Islam agricultural establishment. This study demonstrates the sensitivity of dunes in arid and semi-arid regions to a combination of local and short-term fluctuations in windiness at times of widespread grazing (anthropogenic activity). The results remind us that in similar future scenarios, sand mobilization may be similarly retriggered to varying degrees.

Land and Land-use Change in the Climate Sensitive High Plains: An Automated Approach with Landsat

NASA Technical Reports Server (NTRS)

Goetz, Alexander F.; Williams, D. L. (Technical Monitor)

2002-01-01

The High Plains is an economically important and climatologically sensitive region of the United States and Canada. The High Plains contain 100,000 sq km of Holocene sand dunes and sand sheets that are currently stabilized by natural vegetation. Droughts and the larger threat of global warming are climate phenomena that could cause depletion of natural vegetation and make this region susceptible to sand dune reactivation. The original proposal was directed toward the use of Landsat TM data to establish the state and ongoing changes of the surface in the 1.2 million sq. km, semi-arid High Plains region of the central US, A key objective was to develop a model to predict the reactivation of the 100,000 sq. km of Holocene dunes found on the High Plains during an extended drought. At least one Landsat 5 image per year for 1985, 1988 and 1996 was obtained for 32 scenes on the High Plains to coincide with wet and dry years. Additional Landsat 7 data were acquired for 1999 and 2000 primarily for Colorado and Nebraska. As luck would have it, there was no severe drought during the study period 1985-2000. Attention was focused on developing methods for mapping dry vs. green vegetation on sparsely vegetated rangelands in sandy soils, since these were the areas most susceptible to surface reactivation during a drought.

Distinguishing native (Celastrus scandens L.) and invasive (C. orbiculatus Thunb.) bittersweet species using morphological characteristics

USGS Publications Warehouse

Leicht-Young, S. A.; Pavlovic, N.B.; Grundel, R.; Frohnapple, K.J.

2007-01-01

Celastrus orbiculatus is an invasive liana in the Eastern United States. Its native congener, C. scandens, is less common and declining in the Northeast. The correct identification of these two species is often difficult because of their similar vegetative characteristics. Using morphological characteristics of both species growing naturally along a sand dune/forest ecotone, we built models for use in discriminating between the species, given a suite of leaf and fruit traits. We confirmed that the two species can be discriminated effectively using fruit characters, notably fruit volume and seed number. Several leaf traits, such as length-to-width ratio and leaf apex length can also discriminate between the species, but without the same predictive reliability of fruit traits. In addition, we determined that at leaf out in the spring the leaves of the two species were folded differently in the bud allowing them to be successfully discriminated in the early spring. Land managers could use this information to differentiate between the two species in the field and thereby control for the invasiveC. orbiculatus, while preserving remaining populations of C. scandens.

Interaction of petroleum mulching, vegetation restoration and dust fallout on the conditions of sand dunes in southwest of Iran

NASA Astrophysics Data System (ADS)

Azoogh, Liela; Khalili moghadam, Bijan; Jafari, Siroos

2018-06-01

In the past half-century, petroleum mulching-biological fixation (PM-BF) practices have been employed to stabilize sand dunes in Iran. However, the effects of PM-BF practices on the attributes of sand dunes and the dispersion of heavy metals of mulch have been poorly understood. To this end, three regions treated with PM-BF for 5, 20, and 40 years and a control region with no PM-BF were studied. Samples of soil properties were taken at the depths of 0-10 cm and 10-50 cm, with three replications, in Khuzestan Province. The results showed that PM-BF practices promoted the restoration of vegetation cover in the sand dunes. In addition, these practices increased the deposition of dust particles, gradually increasing the magnitudes of palygorskite and smectite clays over time. The interactions between dust deposition and PM-BF practices significantly altered the chemical and physical properties of the dunes. PM-BF practices increased soil organic matter (184-287%), cation exchangeable capacity (142-209%), electrical conductivity (144-493%), clay content (134-196%), and penetration resistance (107-170%) compared to the region with no PM-BF practices. Furthermore, petroleum mulching significantly increased the amount of Ni (1.19%), Cd (1.55%), Pb (1.08%), Cu (1.34%), Zn (1.38%), Mn (1.66%), and Fe (1.15%). However, in the long term, these elements will probably leach linearly as a consequence of an increase in organic matter and soil salinity in the light texture of sand dunes.

Dynamic dune management, integrating objectives of nature development and coastal safety: Examples from the Netherlands

NASA Astrophysics Data System (ADS)

Arens, Sebastiaan M.; Mulder, Jan P. M.; Slings, Quirinus L.; Geelen, Luc H. W. T.; Damsma, Petra

2013-10-01

This paper discusses and compares results of management interventions to remobilise dunes and obtain more autonomous changes in foredunes resulting from a change in coastal defence policy. In recent decades, nature conservation managers tried to restore aeolian dynamics and dune mobility landward of foredunes to maintain threatened, rare pioneer species. Results indicate that destabilisation activities yielded an important increase of blowing sand and its effects on ecology but with a limited effect on the desired integral remobilization of dunes. Roots remaining in the sand after removal of vegetation and soil is one of the main problems. Follow up removal of roots for 3 to 5 years seems to be essential, but it is not clear whether the dunes will remain mobile in the long term. In 1990 the Dutch government decided to maintain the position of the coastline by artificial sand nourishment. An intensive management of the foredunes was no longer required. Consequently, natural processes in the foredunes revived, and the sediment budget of the beach-dune system changed. Two main types of responses are visible. In some areas, increased input of sand resulted in the development of embryonic dunes seaward of the former foredunes, leading to increased stabilisation of the former foredunes. In other areas, development of embryonic dunes was insignificant despite the increased sand input, but wind erosion features developed in the foredunes, and the environment was more dynamic. The reasons for the differences are not clear, and the interaction between shoreface, beach and dunes is still poorly understood. Until now, attempts to mobilise the inner dunes were independent of changes made to the foredunes. We argue that an integrated, dynamic approach to coastal management, taking account of all relevant functions (including safety and natural values) and the dune-beach system as a whole, may provide new and durable solutions. An integrated approach would ideally provide fresh sand to the system by sand nourishment; define a wide safety zone, which enables the transition zone of beach to foredunes to develop freely; reserve space for natural processes without restrictions; and stimulate natural redistribution of sand within the system and restore inland transport of sand by removing vegetation behind the foredunes. A long time scale (several decades) is needed for this approach to be successful.

Apparent competition with an invasive plant hastens the extinction of an endangered lupine.

PubMed

Dangremond, Emily M; Pardini, Eleanor A; Knight, Tiffany M

2010-08-01

Invasive plants may compete with native plants by increasing the pressure of native consumers, a mechanism known as "apparent competition." Apparent competition can be as strong as or stronger than direct competition, but the role of apparent competition has rarely been examined in biological invasions. We used four years of demographic data and seed-removal experiments to determine if introduced grasses caused elevated levels of seed consumption on native plant species in a coastal dune system in California, USA. We show that the endangered, coastal dune plant Lupinus tidestromii experiences high levels of pre-dispersal seed consumption by the native rodent Peromyscus maniculatus due to its proximity to the invasive grass, Ammophila arenaria. We use stage-structured, stochastic population models to project that two of three study populations will decline toward extinction under ambient levels of consumption. For one of these declining populations, a relatively small decrease in consumption pressure should allow for persistence. We show that apparent competition with an invasive species significantly decreases the population growth rate and persistence of a native species. We expect that apparent competition is an important mechanism in other ecosystems because invasive plants often change habitat structure and plant-consumer interactions. Possible implications of the apparent-competition mechanism include selective extinction of species preferred by seed consumers in the presence of an invasive species and biological homogenization of communities toward non-preferred native plant species.

Earth Observations taken by the Expedition 35 Crew

NASA Image and Video Library

2013-03-25

ISS035-E-009454 (25 March 2013 ) --- One of the Expedition 35 crew members aboard the Earth-orbiting International Space Station used a 400 millimeter lens to photograph this view of the Great Sandy Desert, northwestern Australia on March 25. It bears evidence that much of Australia is arid. In northwest Australia the Great Sandy Desert holds great geological interest as a zone of active sand dune movement; strings of narrow lakes that represent very ancient rivers are also present. While a variety of dune forms can be seen in the region, this photograph features numerous linear dunes (approximately 25 meters high) separated in a roughly regular fashion (0.5?1.5 kilometers), and aligned closely to the winds that generated them?that is, winds blowing from east to west. Where linear dunes converge, dune confluences point downwind. One of the main visual impressions flying over such tropical dune fields ? both from an airplane or from the orbital station outpost?apart from the dune patterns are fire scars where thin vegetation has been burned off the dunes. The result is dunes that appear red from the underlying sand (image top left and top right), and darker areas where the vegetation remains (image lower left and lower right). The white feature visible down the center of the image is Lake Auld, the white color being the result of a cemented combination of fine clayey sediment and salts from evaporation of flood waters that occasionally fill the lake. Wider views of the area show that this lake is part of what is now known to have been a major, ancient river system in northwest Australia, draining northwest to the Indian Ocean. Such sinuous lakes are also known in Australia as ?river lakes.? Scientists point out that the river system is remarkably well preserved considering that the rivers were probably active in the Paleocene Epoch more than 55 million years ago. Australia then lay much further south in a wetter climatic zone. Today?s desert climate results in almost all rivers in the Great Sandy Desert being dry. Linear dunes can be seen entering Lake Auld on the east side. During flooding events, the sand of the dune noses is dispersed, becoming incorporated into the lake floor sediments together with muds and salts. During the long intervening dry periods, sand can blow across the lake floor to build thinner, smaller dunes visible as linear accumulations on the west side of the lake.

Factors influencing the natural regeneration of the pioneering shrub Calligonum mongolicum in sand dune stabilization plantations in arid deserts of northwest China.

PubMed

Fan, Baoli; McHugh, Allen David; Guo, Shujiang; Ma, Quanlin; Zhang, Jianhui; Zhang, Xiaojuan; Zhang, Weixing; Du, Juan; Yu, Qiushi; Zhao, Changming

2018-03-01

Calligonum mongolicum is a successful pioneer shrub to combat desertification, which is widely used for vegetation restoration in the desert regions of northwest China. In order to reveal the limitations to natural regeneration of C. mongolicum by asexual and sexual reproduction, following the process of sand dune stabilization, we assessed clonal shoots, seedling emergence, soil seed bank density, and soil physical characteristics in mobile and stabilized sand dunes. Controlled field and pot experiments were also conducted to assess germination and seedling emergence in different dune soil types and seed burial depths. The population density of mature C. mongolicum was significantly different after sand dune stabilization. Juvenile density of C. mongolicm was much lower in stabilized sand dunes than mobile sand dune. There was no significant difference in soil seed bank density at three soil depths between mobile and stabilized sand dunes, while the emergence of seedlings in stabilized dunes was much lower than emergence in mobile dunes. There was no clonal propagation found in stabilized dunes, and very few C. mongolicum seedlings were established on stabilized sand dunes. Soil clay and silt content, air-filled porosity, and soil surface compaction were significantly changed from mobile sand dune to stabilized dunes. Seedling emergence of C. mongolicm was highly dependent on soil physical condition. These results indicated that changes in soil physical condition limited clonal propagation and seedling emergence of C. mongolicum in stabilized sand dunes. Seed bank density was not a limiting factor; however, poor seedling establishment limited C. mongolicum's further natural regeneration in stabilized sand dunes. Therefore, clonal propagation may be the most important mode for population expansion in mobile sand dunes. As a pioneer species C. mongolicum is well adapted to propagate in mobile sand dune conditions, it appears unlikely to survive naturally in stabilized sand dune plantations.

Barrier Island Morphology and Sediment Characteristics Affect the Recovery of Dune Building Grasses following Storm-Induced Overwash

PubMed Central

Brantley, Steven T.; Bissett, Spencer N.; Young, Donald R.; Wolner, Catherine W. V.; Moore, Laura J.

2014-01-01

Barrier islands are complex and dynamic systems that provide critical ecosystem services to coastal populations. Stability of these systems is threatened by rising sea level and the potential for coastal storms to increase in frequency and intensity. Recovery of dune-building grasses following storms is an important process that promotes topographic heterogeneity and long-term stability of barrier islands, yet factors that drive dune recovery are poorly understood. We examined vegetation recovery in overwash zones on two geomorphically distinct (undisturbed vs. frequently overwashed) barrier islands on the Virginia coast, USA. We hypothesized that vegetation recovery in overwash zones would be driven primarily by environmental characteristics, especially elevation and beach width. We sampled species composition and environmental characteristics along a continuum of disturbance from active overwash zones to relict overwash zones and in adjacent undisturbed environments. We compared species assemblages along the disturbance chronosequence and between islands and we analyzed species composition data and environmental measurements with Canonical Correspondence Analysis to link community composition with environmental characteristics. Recovering and geomorphically stable dunes were dominated by Ammophila breviligulata Fernaud (Poaceae) on both islands while active overwash zones were dominated by Spartina patens (Aiton) Muhl. (Poaceae) on the frequently disturbed island and bare sand on the less disturbed island. Species composition was associated with environmental characteristics only on the frequently disturbed island (p = 0.005) where A. breviligulata was associated with higher elevation and greater beach width. Spartina patens, the second most abundant species, was associated with larger sediment grain size and greater sediment size distribution. On the less frequently disturbed island, time since disturbance was the only factor that affected community composition. Thus, factors driving the abundance of dune-building grasses and subsequent recovery of dunes varied between the two geomorphically distinct islands. PMID:25148028

Mapping the Potential for Eolian Surface Activity in Grasslands of the High Plains using Landsat Images

NASA Technical Reports Server (NTRS)

Gutmann, Ethan Dain

2002-01-01

There are over 100,000 square kilometers of eolian sand dunes and sand sheets in the High Plains of the central United States. These land-forms may be unstable and may reactivate again as a result of land-use, climate change, or natural climatic variability. The main goal of this thesis was to develop a model that could be used to map an estimate of future dune activity. Multi-temporal calibrated Landsats 5 Thematic Mapper (TM) and 7 Enhanced Thematic Map per Plus (ETM+) NDVI imagery were used in conjunction with the CENTURY vegetation model to correlate vegetation cover to climatic variability. This allows the creation of a predicted vegetation map which, combined with current wind and soil data, was used to create a potential sand transport map for range land in the High Plains under drought conditions.

Responses to invasion and invader removal differ between native and exotic plant groups in a coastal dune.

PubMed

Magnoli, Susan M; Kleinhesselink, Andrew R; Cushman, J Hall

2013-12-01

The spread of exotic, invasive species is a global phenomenon that is recognized as a major source of environmental change. Although many studies have addressed the effects of exotic plants on the communities they invade, few have quantified the effects of invader removal on plant communities, or considered the degree to which different plant groups vary in response to invasion and invader removal. We evaluated the effects of an exotic succulent, iceplant (Carpobrotus edulis), on a coastal dune plant community in northern California, as well as the community responses to its removal. To assess possible mechanisms by which iceplant affects other plants, we also evaluated its above- and belowground influences on the germination and growth of a dominant exotic annual grass, Bromus diandrus. We found that iceplant invasion was associated with reduced native plant cover as well as increased cover and density of some exotic plants-especially exotic annual grasses. However, iceplant removal did not necessarily lead to a reversal of these effects: removal increased the cover and density of both native and exotic species. We also found that B. diandrus grown in iceplant patches, or in soil where iceplant had been removed, had poorer germination and growth than B. diandrus grown in soil not influenced by iceplant. This suggests that the influence of iceplant on this dune plant community occurs, at least in part, due to belowground effects, and that these effects remain after iceplant has been removed. Our study demonstrates the importance of considering how exotic invasive plants affect not only native species, but also co-occurring exotic taxa. It also shows that combining observational studies with removal experiments can lead to important insights into the influence of invaders and the mechanisms of their effects.

Quantifying BRDF Effects in Comparing Landsat-7 and AVIRIS Near-Simultaneous Acquisitions for Studies of High Plains Vegetation Cover

NASA Technical Reports Server (NTRS)

Goetz, A. F. H.; Heidebrecht, K. B.; Gutmann, E. D.; Warner, A. S.; Johnson, E. L.; Lestak, L. R.

1999-01-01

Approximately 100,000 sq. km of the High Plains of the central United States are covered by sand dunes and sand sheets deposited during the Holocene. Soil-dating evidence shows that there were at least four periods of dune reactivation during major droughts in the last 10,000 years. The dunes in this region are anchored by vegetation. We have undertaken a study of land-use change in the High Plains from 1985 to the present using Landsat 5 TM and Landsat 7 ETM+ images to map variation in vegetation cover during wet and dry years. Mapping vegetation cover of less than 20% is important in modeling potential surface reactivation since at this level the vegetation no longer sufficiently shields sandy surfaces from movement by wind. Landsat TM data have both the spatial resolution and temporal coverage to facilitate vegetation cover analysis for model development and verification. However, there is still the question of how accurate TM data are for the measurement of both growing and senescent vegetation in and and semi-arid regions. AVIRIS provides both high spectral resolution as well as high signal-to-noise ratio and can be used to test the accuracy of Landsat TM and ETM+ data. We have analyzed data from AVIRIS flown nearly concurrently with a Landsat 7 overpass. The comparison between an AVIRIS image swath of 11 km width subtending a 30 deg. angle and the same area covered by a 0.8 deg. angle from Landsat required accounting for the BRDF. A normalization technique using the ratio of the reflectances from registered AVIRIS and Landsat data proved superior to the techniques of column averaging on AVIRIS data alone published previously by Kennedy et al. This technique can be applied to aircraft data covering a wider swath angle than AVIRIS to develop BRDF responses for a wide variety of surfaces more efficiently than from ground measurements.

Aeolian Shear Stress Ratio Measurements within Mesquite-Dominated Landscapes of the Chihuahuan Desert, New Mexico, USA

NASA Technical Reports Server (NTRS)

King, James; Nickling, W. G.; Gilliles, J. A.

2006-01-01

A field study was conducted to ascertain the amount of protection that mesquite-dominated communities provide to the surface from wind erosion. The dynamics of the locally accelerated evolution of a mesquite/coppice dune landscape and the undetermined spatial dependence of potential erosion by wind from a shear stress partition model were investigated. Sediment transport and dust emission processes are governed by the amount of protection that can be provided by roughness elements. Although shear stress partition models exist that can describe this, their accuracy has only been tested against a limited dataset because instrumentation has previously been unable to provide the necessary measurements. This study combines the use of meteorological towers and surface shear stress measurements with Irwin sensors to measure the partition of shear stress in situ. The surface shear stress within preferentially aligned vegetation (within coppice dune development) exhibited highly skewed distributions, while a more homogenous surface stress was recorded at a site with less developed coppice dunes. Above the vegetation, the logarithmic velocity profile deduced roughness length (based on 10-min averages) exhibited a distinct correlation with compass direction for the site with vegetation preferentially aligned, while the site with more homogenously distributed vegetation showed very little variation in the roughness length. This distribution in roughness length within an area, defines a distribution of a resolved shear stress partitioning model based on these measurements, ultimately providing potential closure to a previously uncorrelated model parameter.

Aeolian shear stress ratio measurements within mesquite-dominated landscapes of the Chihuahuan Desert, New Mexico, USA

NASA Astrophysics Data System (ADS)

King, James; Nickling, W. G.; Gillies, J. A.

2006-12-01

A field study was conducted to ascertain the amount of protection that mesquite-dominated communities provide to the surface from wind erosion. The dynamics of the locally accelerated evolution of a mesquite/coppice dune landscape and the undetermined spatial dependence of potential erosion by wind from a shear stress partition model were investigated. Sediment transport and dust emission processes are governed by the amount of protection that can be provided by roughness elements. Although shear stress partition models exist that can describe this, their accuracy has only been tested against a limited dataset because instrumentation has previously been unable to provide the necessary measurements. This study combines the use of meteorological towers and surface shear stress measurements with Irwin sensors to measure the partition of shear stress in situ. The surface shear stress within preferentially aligned vegetation (within coppice dune development) exhibited highly skewed distributions, while a more homogenous surface stress was recorded at a site with less developed coppice dunes. Above the vegetation, the logarithmic velocity profile deduced roughness length (based on 10-min averages) exhibited a distinct correlation with compass direction for the site with vegetation preferentially aligned, while the site with more homogenously distributed vegetation showed very little variation in the roughness length. This distribution in roughness length within an area, defines a distribution of a resolved shear stress partitioning model based on these measurements, ultimately providing potential closure to a previously uncorrelated model parameter.

Groundwater dynamics converted to a groundwater classification as a tool for nature development programs in the dunes

NASA Astrophysics Data System (ADS)

Martens, Kristine; Van Camp, Marc; Van Damme, Dirk; Walraevens, Kristine

2013-08-01

Within the European Union, Habitat Directives are developed with the aim of restoration and preservation of endangered species. The level of biodiversity in coastal dune systems is generally very high compared to other natural ecosystems, but suffers from deterioration. Groundwater extraction and urbanisation are the main reasons for the decrease in biodiversity. Many restoration actions are being carried out and are focusing on the restoration of groundwater level with the aim of re-establishing rare species. These actions have different degrees of success. The evaluation of the actions is mainly based on the appearance of red list species. The groundwater classes, developed in the Netherlands, are used for the evaluation of opportunities for vegetation, while the natural variability of the groundwater level and quality are under-estimated. Vegetation is used as a seepage indicator. The existing classification is not valid in the Belgian dunes, as the vegetation observed in the study area is not in correspondence with this classification. Therefore, a new classification is needed. The new classification is based on the variability of the groundwater level on a long term with integration of ecological factors. Based on the new classification, the importance of seasonal and inter-yearly fluctuations of the water table can be deduced. Inter-yearly fluctuations are more important in recharge areas while seasonal fluctuations are dominant in discharge areas. The new classification opens opportunities for relating vegetation and groundwater dynamics.

A Late Pleistocene linear dune dam record of aeolian-fluvial dynamics at the fringes of the northwestern Negev dunefield

NASA Astrophysics Data System (ADS)

Roskin, Joel; Bookman, Revital; Friesem, David; Vardi, Jacob

2017-04-01

The paper presents a late Pleistocene aeolian-fluvial record within a linear dune-like structure that partway served as a dune dam. Situated along the southern fringe of the northwestern Negev desert dunefield (Israel) the structure's morphology, orientation, and some of its stratigraphic units partly resemble adjacent west-east extending vegetated linear dunes. Uneven levels of light-colored, fine-grained fluvial deposits (LFFDs) extend to the north and south from the flanks of the studied structure. Abundant Epipalaeolithic sites line the fringes of the LFFDs. The LFFD microstructures of fine graded bedding and clay blocky peds indicate sorting and shrinking of saturated clays in transitional environments between low energy flows to shallow standing water formed by dunes damming a mid-sized drainage system. The structure's architecture of interchanging units of sand with LFFDs indicates interchanging dominances between aeolian sand incursion and winter floods. Sand mobilization associated with powerful winds during the Heinrich 1 event led to dune damming downstream of the structure and within the structure to in-situ sand deposition, partial fluvial erosion, reworking of the sand, and LFFD deposition. Increased sand deposition led to structure growth and blockage of its drainage system that in turn accumulated LFFD units up stream of the structure. Extrapolation of current local fluvial sediment yields indicate that LFFD accretion up to the structure's brim occurred over a short period of several decades. Thin layers of Geometric Kebaran (c. 17.5-14.5 ka cal BP) to Harifian (12-11 ka BP) artifacts within the structure's surface indicates intermittent, repetitive, and short term camping utilizing adjacent water along a timespan of 4-6 kyr. The finds directly imply that the NW Negev LFFDs formed in dune-dammed water bodies which themselves were formed following events of vegetated linear dune elongation. LFFD accumulation persisted as a result of dune dam maintenance by smaller sand mobilization events. Wetter climates increased flood events boosting LFFD buildup rates but shortened dune dam longevity. The abundance and recurrence of water bodies in middle and large basins deteriorated after Harifian times when reduced wind power during the post-Younger Dryas constrained dune dam maintenance. Eventually, dune dam incision began as a result of overland flow after accommodation space dissipated due to LFFD accretion. Altogether, fluctuating high wind power and precipitation during a glacial-interglacial time window and high availability of fine-grained fluvial sediment yield from eroded middle to late Pleistocene upstream highlands loess mantles, combined to create a trio of aeolian-fluvial forcing factors supporting short-term but amplified dune-dammed fluvial depositional conditions.

Defrosting Polar Dunes--"They Look Like Bushes!"

NASA Image and Video Library

2000-05-26

"They look like bushes!" That's what almost everyone says when they see the dark features found in pictures taken of sand dunes in the polar regions as they are beginning to defrost after a long, cold winter. It is hard to escape the fact that, at first glance, these images acquired by the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) over both polar regions during the spring and summer seasons, do indeed resemble aerial photographs of sand dune fields on Earth -- complete with vegetation growing on and around them! Of course, this is not what the features are, as we describe below and in related picture captions. Still, don't they look like vegetation to you? Shown here are two views of the same MGS MOC image. On the left is the full scene, on the right is an expanded view of a portion of the scene on the left. The bright, smooth surfaces that are dotted with occasional, nearly triangular dark spots are sand dunes covered by winter frost. The MGS MOC has been used over the past several months (April-August 1999) to monitor dark spots as they form and evolve on polar dune surfaces. The dark spots typically appear first along the lower margins of a dune -- similar to the position of bushes and tufts of grass that occur in and among some sand dunes on Earth. Because the martian air pressure is very low -- 100 times lower than at Sea Level on Earth -- ice on Mars does not melt and become liquid when it warms up. Instead, ice sublimes -- that is, it changes directly from solid to gas, just as "dry ice" does on Earth. As polar dunes emerge from the months-long winter night, and first become exposed to sunlight, the bright winter frost and snow begins to sublime. This process is not uniform everywhere on a dune, but begins in small spots and then over several months it spreads until the entire dune is spotted like a leopard. The early stages of the defrosting process -- as in the picture shown here -- give the impression that something is "growing" on the dunes. The sand underneath the frost is dark, just like basalt beach sand in Hawaii. Once it is exposed to sunlight, the dark sand probably absorbs sunlight and helps speed the defrosting of each sand dune. This picture was taken by MGS MOC on July 21, 1999. The dunes are located in the south polar region and are expected to be completely defrosted by November or December 1999. North is approximately up, and sunlight illuminates the scene from the upper left. The 500 meter scale bar equals 547 yards; the 300 meter scale is also 328 yards. http://photojournal.jpl.nasa.gov/catalog/PIA02300

Remote Sensing Field Guide - Desert

DTIC Science & Technology

1991-09-01

rcatching on fire. Caution is advised against thorns on acacia trees, spikey Spinifex n•shes, and several different types of venomous snakes, as well as...e.g., mesquite, many acacias, Spinifex . DESERT PROCESSES WORKING GROUP PATTERN INDICATOR SHFET - DESERT DUNES PHOTOS: GROUND VEGETATION MOUNDS LOCATION...deliberate burning of natural vegetation is done episodically by the abo- rginal inhabitants. They burn the mature vegetation (primarily Spinifex ), which is

Propagation and Establishment of Native Plants for Vegetative Restoration of Aquatic Ecosystems

DTIC Science & Technology

2013-06-01

diverse native plant communities in aquatic systems. We document the successful application of these techniques in a number of aquatic ecosystems...Aquatic Plant Control Research Program (APCRP) for establishing native aquatic plants in reservoirs and other water bodies. These techniques should...that some control techniques may negatively affect efforts to establish native vegetation. Establishing native aquatic vegetation is not an exact

The Demise of the Circumboreal Mammoth Steppe as an Ecological Regime Shift: Drivers and Consequences

NASA Astrophysics Data System (ADS)

Mann, D. H.; Groves, P.; Grosse, G.; Gaglioti, B.; Kunz, M.

2011-12-01

During the last ice age, the now-vanished Mammoth Steppe stretched from the Yukon westward to Europe and supported a unique guild of megafauna grazers including mammoth, bison, saiga, wooly rhinoceros, caribou, muskox, and horse. The detailed vegetational composition of this extinct biome remains uncertain because of its large size and temporal complexity during multiple climatic shifts. Grasses and sedges were prominent, and Mammoth Steppe vegetation was probably more spatially variable than the tundra and taiga vegetation that replaced it. The environmental factors that maintained the Mammoth Steppe and dictated its variability over time and space are poorly understood. Here we present evidence for an expanded version of the "Schweger Hypothesis", the idea that large regions of the Mammoth Steppe were created and maintained by processes associated with aeolian sediment activity that was driven by enhanced pressure gradients in the full-glacial atmosphere and by increased continentality caused by lowered sea level. Increased seasonal swings in climate plus stronger winds interacted to promote the widespread occurrence of steppe-like vegetation that grew on relatively inactive and marginal dune and loess deposits. Subsequent periods of resumed aeolian deposition or reworking would have inhibited thick organic horizon development which are largely absent from full glacial mammoth steppe. New mapping of sand dune systems in Siberia and improved chronological control over dune fields in Alaska demonstrate the presence of large dune fields and loess belts in the regions occupied by the Mammoth Steppe during the Last Glacial Maximum. In regions of north Siberia, intense periglacial weathering and local transport of sediments also contributed to development and maintenance of the Mammoth Steppe. Local areas where aeolian sediment activity persists today such as active dune fields and loessal soils share several characteristics with the mammoth steppe such as the abundance grass and sedges, firm substrates, and unusual mixtures of steppe and tundra vegetation. What caused the demise of the Mammoth Steppe is unclear, however understanding what maintained it over space and time would greatly aid this discussion. The habitat shift began ca. 12,500 14C yr BP and continued for approximately 2000 years. It coincided with a shift from well-drained, mineral soils to poorly drained, organic-rich ones. This regime shift may have been more significant than changes during previous interglacial climatic shifts as most megafaunal species adapted to life in the Mammoth Steppe experienced radical range reductions and, in some cases, global extinction during this period.

Vulnerability Assessment of a Coastal Dune System at São Francisco do Sul Island, Santa Catarina, Brazil

NASA Astrophysics Data System (ADS)

Alquini, Fernanda; Bertoni, Duccio; Sarti, Giovanni; Ciccarelli, Daniela; Pozzebon, Alessandro; Ferreira de Melo Júnior, João Carlos; Voos Vieira, Celso

2016-10-01

In this paper a Coastal Dune Vulnerability Index (CDVI) has been applied on a beach located in the eastern side of Sao Francisco do Sul Island (Brazil). The aim of this study is to assess the vulnerability of a coastal dune system and to identify the areas that result most sensitive to environmental changes. The CDVI has been applied along six transects traced out on two sectors that have been selected based on dune characteristics: Zone A is characterized by well developed parabolic dunes, whereas Zone B is characterized by transverse dunes. The analysis involved 51 quantitative and qualitative variables, divided into five groups: geomorphological dune system condition, marine influence, Aeolian effect, vegetation condition and human effect. The total CDVI was computed as the unweighted average of the partial vulnerability indices. In summary, the total vulnerability can be classified as medium: the geomorphological factor must be monitored at Grande beach, in particular the blowouts in Zone A and the frontal dune retreat in Zone B. The results of the study confirm that the management of coastal areas might be improved using a tool such as the CDVI, which can be easily applied on a regular basis to take under control the factors that mostly affect the evolution of the site.

The effects of psammophilous plants on sand dune dynamics

NASA Astrophysics Data System (ADS)

Bel, Golan; Ashkenazy, Yosef

2014-07-01

Mathematical models of sand dune dynamics have considered different types of sand dune cover. However, despite the important role of psammophilous plants (plants that flourish in moving-sand environments) in dune dynamics, the incorporation of their effects into mathematical models of sand dunes remains a challenging task. Here we propose a nonlinear physical model for the role of psammophilous plants in the stabilization and destabilization of sand dunes. There are two main mechanisms by which the wind affects these plants: (i) sand drift results in the burial and exposure of plants, a process that is known to result in an enhanced growth rate, and (ii) strong winds remove shoots and rhizomes and seed them in nearby locations, enhancing their growth rate. Our model describes the temporal evolution of the fractions of surface cover of regular vegetation, biogenic soil crust, and psammophilous plants. The latter reach their optimal growth under either (i) specific sand drift or (ii) specific wind power. The model exhibits complex bifurcation diagrams and dynamics, which explain observed phenomena, and it predicts new dune stabilization scenarios. Depending on the climatological conditions, it is possible to obtain one, two, or, predicted here for the first time, three stable dune states. Our model shows that the development of the different cover types depends on the precipitation rate and the wind power and that the psammophilous plants are not always the first to grow and stabilize the dunes.

Effects of prolonged drought on the vegetation cover of sand dunes in the NW Negev Desert: Field survey, remote sensing and conceptual modeling

NASA Astrophysics Data System (ADS)

Siegal, Z.; Tsoar, H.; Karnieli, A.

2013-06-01

Luminescence dating of stable sand dunes in the large deserts of the world has shown several episodes of mobility during the last 30 k years. The logical explanation for the mobility of fixed dunes is severe drought. Though drought length can be estimated, the level of precipitation drop is unknown. The stabilized sand dunes of the northwestern Negev Desert, Israel have been under an unprecedented prolonged drought since 1995. This has resulted in a vast decrease of shrubs cover on the fixed sand dunes, which changes along the rainfall gradient. In the north, an average of 27% of the shrubs had wilted by 2009, and in the drier southern area, 68% of the shrubs had withered. This loss of shrubbery is not expected to induce dune remobilization because the existing bio-crust cover is not negatively affected by the drought. Eleven aerial photographs taken over the drier southern area from 1956 to 2005 show the change in shrub cover due to human impact and the recent severe drought.

Vegetation studies on Vandenberg Air Force Base, California

NASA Technical Reports Server (NTRS)

Schmalzer, Paul A.; Hickson, Diana E.; Hinkle, C. Ross

1988-01-01

Vandenburg Air Force Base, located in coastal central California with an area of 98,400 ac, contains resources of considerable biological significance. Available information on the vegetation and flora of Vandenburg is summarized and new data collected in this project are presented. A bibliography of 621 references dealing with vegetation and related topics related to Vanderburg was compiled from computer and manual literature searches and a review of past studies of the base. A preliminary floristic list of 642 taxa representing 311 genera and 80 families was compiled from past studies and plants identified in the vegetation sampling conducted in this project. Fifty-two special interest plant species are known to occur or were suggested to occur. Vegetation was sampled using permanent plots and transects in all major plant communities including chaparral, Bishop pine forest, tanbark oak forest, annual grassland, oak woodland, coastal sage scrub, purple sage scrub, coastal dune scrub, coastal dunes, box elder riparian woodland, will riparian woodland, freshwater marsh, salt marsh, and seasonal wetlands. Comparison of the new vegetation data to the compostie San Diego State University data does not indicate major changes in most communities since the original study. Recommendations are made for additional studies needed to maintain and extend the environmental data base and for management actions to improve resource protection.

Creating dune landscapes for nature and housing - how to assess the designs?

NASA Astrophysics Data System (ADS)

van den Ancker, J.; Jungerius, P. D.; Hartman, J.

2012-04-01

Over the last decades landscape and nature organisations in The Netherlands initiated discussions about safeguarding characteristic historical landscapes, as well as improving nature and landscape quality. In these discussions they were supported by Dutch government agencies and newspapers. As a consequence, architects, landscape architects and building firms in the Netherlands try to upgrade the quality of houses and build-up areas by creating special landscape settings. Dunes are one of the landscapes that appeal to the designers, and several projects make use of dunes to create a quality living environment. Also nature manager construct dunes in what is called 'new nature'. This contribution evaluates several projects creating dune landscapes. Criteria for the evaluation are: - the subsequent geomorphology, - the materials used for construction, - the resulting internal structure, - the soil profile, - the relationship with the vegetation, - the historical integrity of the location. These examples indicate that engaging earth-scientific knowhow would substantially improve the authenticity of the designs.

MODELING FLOW PATTERNS IN A SMALL VEGETATED AREA IN THE NORTHERN CHICHUAHUAN DESERT USING QUIC ( QUIC URBAN AND INDUSTRIAL COMPLEX )

EPA Science Inventory

Sandstorms are frequent in the northern Chihuahuan Desert in New Mexico, an area characterized by open areas lacking vegetation, individual mesquite bushes, and mesquite coppice dunes. Field measurements of sand fluxes and wind velocities over a two year period provided a descri...

Dune recovery after storm erosion on a high-energy beach: Vougot Beach, Brittany (France)

NASA Astrophysics Data System (ADS)

Suanez, Serge; Cariolet, Jean-Marie; Cancouët, Romain; Ardhuin, Fabrice; Delacourt, Christophe

2012-02-01

On 10th March 2008, the high energy storm Johanna hit the French Atlantic coast, generating severe dune erosion on Vougot Beach (Brittany, France). In this paper, the recovery of the dune of Vougot Beach is analysed through a survey of morphological changes and hydrodynamic conditions. Data collection focused on the period immediately following storm Johanna until July 2010, i.e. over two and a half years. Results showed that the dune retreated by a maximum of almost 6 m where storm surge and wave attack were the most energetic. Dune retreat led to the creation of accommodation space for the storage of sediment by widening and elevating space between the pre- and post-storm dune toe, and reducing impacts of the storm surge. Dune recovery started in the month following the storm event and is still ongoing. It is characterised by the construction of "secondary" embryo dunes, which recovered at an average rate of 4-4.5 cm per month, although average monthly volume changes varied from - 1 to 2 m 3.m - 1 . These embryo dunes accreted due to a large aeolian sand supply from the upper tidal beach to the existing foredune. These dune-construction processes were facilitated by growth of vegetation on low-profile embryo dunes promoting backshore accretion. After more than two years of survey, the sediment budget of the beach/dune system showed that more than 10,000 m 3 has been lost by the upper tidal beach. We suggest that seaward return currents generated during the storm of 10th March 2008 are responsible for offshore sediment transport. Reconstitution of the equilibrium beach profile following the storm event may therefore have generated cross-shore sediment redistribution inducing net erosion in the tidal zone.

Geomorphology and anthropogenic impact including military constraints in a microtidal wave-dominated embayment in south western Sardinia (Porto Pino beach, SCI ITB040025, Mediterranean Sea). Implications for beach management.

NASA Astrophysics Data System (ADS)

De Muro, Sandro; Buosi, Carla; Pusceddu, Nicola; Frongia, Paolo; Passarella, Marinella; Ibba, Angelo

2016-04-01

The coastal zones of the Mediterranean have undergone increasing pressure over the last century. The intensifying coastal development and the increasing tourist impact have led to an intense transformation of the coastlines and adjacent marine areas. The beach and the coastal dune play an important role in protecting the coastline. Thus, the study of its geomorphological evolution and of its anthropic modification is fundamental in order to adopt the best management practices. In this regard, the LIFE Project (LIFE13NAT/IT/001013) SOSS DUNES (Safeguard and management Of South-western Sardinian Dunes) aims to safeguard the dune habitats and the beach system in a site belonging to the Natura 2000 network, an EUwide network of nature protection areas established under the 1992 Habitats Directive. This project is focused on a microtidal wave-dominated embayment located in south western Sardinia (Italy, Mediterranean Sea) called Porto Pino beach comprised in the SCI (Site of Community Importance) "Promontory, dunes and wetland of Porto Pino (ITB040025)". This research aims to investigate the geomorphological processes, the evolution and the main human impacts on Porto Pino beach as an useful tool for both conservation and coastal management. The coastal area of Porto Pino is represented by sandy shorelines extending for a total length of 5 km characterized by a wide primary and secondary dune systems, a backshore wetland lagoon and marsh area arranged parallel to the coastline. This littoral area can be ideally divided into three parts: the first, about 600 m long, in the north-west part characterized by the highest human pressure due to touristic activity on the foredunes and deposition of beach wrack; the second part in the south-east, about 1100 m long, characterized by a complex dune system (primary and secondary foredunes); and the third southernmost part included in a military area, about 3300 m long, characterized by transgressive dune system with low human impact. The coastal dunes vulnerability status of this three parts was assessed using the Dune Vulnerability Index (DVI) based on 57 variables that described geomorphological condition, marine influence, aeolian influence, vegetation condition, and human effects. Results reveal the lowest vulnerability value in the area undergone military constraints. Blowouts, breaches in the coastal dune system and deflation areas are observed in the first and second part where there is the greatest human transit to allow users access of the beach. The main pressures and threats identified that determine significant impacts on dune habitats are: transit of vehicles in the dune with the subsequent degradation of vegetation and the triggering of deflation processes; setting of infrastructure on the dune; removal of seagrass banquettes. In particular, the impact of trucks used to remove banquettes is significant on subaerial beach morphology. This traffic flattens the berms, modifies sand permeability and reduces organic sediment input to the shore. This study has allowed to highlight the geomorphological processes, the anthropic pressure and the coastal dune vulnerability of this coastal area in order to mitigate the impacts.

National Park Service vegetation inventory program: Mississippi National River and Recreation Area, Minnesota

USGS Publications Warehouse

Hop, Kevin D.; Drake, Jim; Strassman, Andrew C.; Hoy, Erin E.; Jakusz, Joseph; Menard, Shannon; Dieck, Jennifer

2015-01-01

The Mississippi National River and Recreation Area (MISS) vegetation mapping project is an initiative of the National Park Service (NPS) Vegetation Inventory Program (VIP) to classify and map vegetation types of MISS. (Note: “MISS” is also referred to as “park” throughout this report.) The goals of the project are to adequately describe and map vegetation types of the park and to provide the NPS Natural Resource Inventory and Monitoring (I&M) Program, resource managers, and biological researchers with useful baseline vegetation information.The MISS vegetation mapping project was officially started in spring 2012, with a scoping meeting wherein partners discussed project objectives, goals, and methods. Major collaborators at this meeting included staff from the NPS MISS, the NPS Great Lakes Network (GLKN), NatureServe, and the USGS Upper Midwest Environmental Sciences Center. The Minnesota Department of Natural Resources (DNR) was also in attendance. Common to all NPS VIP projects, the three main components of the MISS vegetation mapping project are as follows: (1) vegetation classification, (2) vegetation mapping, and (3) map accuracy assessment (AA). In this report, each of these fundamental components is discussed in detail.With the completion of the MISS vegetation mapping project, all nine park units within the NPS GLKN have received vegetation classification and mapping products from the NPS and USGS vegetation programs. Voyageurs National Park and Isle Royale National Park were completed during 1996–2001 (as program pilot projects) and another six park units were completed during 2004–11, including the Apostle Islands National Lakeshore, Grand Portage National Monument, Indiana Dunes National Lakeshore, Pictured Rocks National Lakeshore, Saint Croix National Scenic Riverway, and Sleeping Bear Dunes National Lakeshore.

Encroachment of oriental bittersweet into Pitcher’s thistle habitat

USGS Publications Warehouse

Leicht-Young, Stacey A.; Pavlovic, Noel B.

2012-01-01

Common invasive species and rare endemic species can grow and interact at the ecotone between forested and non-forested dune habitats. To investigate these interactions, a comparison of the proximity and community associates of a sympatric invasive (Celastrus orbiculatus; oriental bittersweet) and native (C. scandens; American bittersweet) liana species to federally threatened Cirsium pitcheri (Pitcher's thistle) in the dunes habitats of Lake Michigan was conducted. Overall, the density of the invasive liana species was significantly greater in proximity to C. pitcheri than the native species. On the basis of composition, the three focal species occurred in both foredune and blowout habitats. The plant communities associated with the three focal species overlapped in ordination space, but there were significant differences in composition. The ability of C. orbiculatus to rapidly grow and change the ecological dynamics of invasion sites adds an additional threat to the successional habitats of C. pitcheri.

The influence of groundwater depth on coastal dune development at sand flats close to inlets

NASA Astrophysics Data System (ADS)

Silva, Filipe Galiforni; Wijnberg, Kathelijne M.; de Groot, Alma V.; Hulscher, Suzanne J. M. H.

2018-05-01

A cellular automata model is used to analyze the effects of groundwater levels and sediment supply on aeolian dune development occurring on sand flats close to inlets. The model considers, in a schematized and probabilistic way, aeolian transport processes, groundwater influence, vegetation development, and combined effects of waves and tides that can both erode and accrete the sand flat. Next to three idealized cases, a sand flat adjoining the barrier island of Texel, the Netherlands, was chosen as a case study. Elevation data from 18 annual LIDAR surveys was used to characterize sand flat and dune development. Additionally, a field survey was carried out to map the spatial variation in capillary fringe depth across the sand flat. Results show that for high groundwater situations, sediment supply became limited inducing formation of Coppice-like dunes, even though aeolian losses were regularly replenished by marine import during sand flat flooding. Long dune rows developed for high sediment supply scenarios which occurred for deep groundwater levels. Furthermore, a threshold depth appears to exist at which the groundwater level starts to affect dune development on the inlet sand flat. The threshold can vary spatially depending on external conditions such as topography. On sand flats close to inlets, groundwater is capable of introducing spatial variability in dune growth, which is consistent with dune development patterns found on the Texel sand flat.

Correlation of aeolian sediment transport measured by sand traps and fluorescent tracers

NASA Astrophysics Data System (ADS)

Cabrera, Laura L.; Alonso, Ignacio

2010-03-01

Two different methods, fluorescent tracers and vertical sand traps, were simultaneously used to carry out an aeolian sediment transport study designed to test the goodness of fluorescent tracers in aeolian environments. Field experiments were performed in a nebkha field close to Famara beach at Lanzarote Island (Canary Islands, Spain) in a sector where the dunes were between 0.5 and 0.8 m height and 1-2 m wide and the vegetal cover was approximately 22%. In this dune field the sediment supply comes from Famara beach and is blown by trade winds toward the south, where the vegetation acts as natural sediment traps. Wind data were obtained by means of four Aanderaa wind speed sensors and one Aanderaa vane, all them distributed in a vertical array from 0.1 to 4 m height for 27 h. The average velocity at 1 m height during the experiment was 5.26 m s - 1 with the wind direction from the north. The tracer was under wind influence for 90 min at midday. During this period two series of sand traps (T1 and T2) N, S, E and W oriented were used. Resultant transport rates were 0.0131 and 0.0184 kg m - 1 min - 1 respectively. Tracer collection was performed with a sticky tape to sample only surface sediments. Tagged grains were visually counted under UV light. The transport rate was computed from the centroid displacement, that moved 0.875 m southwards, and the depth of the active layer considered was the size of one single grain. Taking into account these data the transport rate was 0.0072 kg m - 1 min - 1 . The discrepancy in results between both methods is related to several factors, such as the thickness of the active layer and the grain size difference between the tagged and the native material.

Why do seif dunes meander?

NASA Astrophysics Data System (ADS)

Kryger, Mateusz; Bubenzer, Olaf; Parteli, Eric

2017-04-01

Seif dunes - which develop in the absence of vegetation and elongate in the resultant sand transport direction - are the prevailing dune type in many deserts of Earth and Mars and display a meandering shape that has challenged geomorphologists for decades. Understanding the factors controlling seif dune morphology may have impact for a broad range of scientific areas, in particular in the investigation of planetary wind regimes, as dune shape is primarily affected by wind directionality. Sand roses of areas hosting seif dunes display, in general, two main wind directions that form a divergence angle larger than 90˚ . Indeed, theory of dune formation predicts that longitudinal alignment of aeolian bedforms occurs under obtuse bimodal winds, a prediction that has been confirmed by field observations and numerical simulations of aeolian dunes, as well as by experiments on subaqueous bedforms. However, numerical simulations and water tank experiments performed under conditions of bimodal flows could never reproduce one of the most salient characteristics of the seif dune shape, which is its meandering. Instead, longitudinal dunes produced in such simulations and experiments display an unrealistic straight shape, which elongates into the resultant transport trend without developing the sinuous morphology of the seif dunes. Here we show, by means of morphodynamic modeling of aeolian sediment transport and dune formation under directionally varying flows, that the meandering shape of seif dunes can be explained by the action of subordinated sand-moving winds, which occur in addition to both main wind components of the bimodal wind. Because such subordinated winds - inherent to most measured sand roses of seif dune fields - are associated with transport rates much smaller than the sand flux values of the main bimodal wind components - they have been long thought to be negligible for dune shape. However, our simulations show that meandering may be caused by a single secondary wind component in the sand rose with transport rate of about 1/5 of the flux due to the bimodal wind components. To verify our model we calculate dune formation using the sand rose of the seif dune field in Bir Lahfan, Sinai, and find good quantitative agreement between the shape of seif dunes in this field and the dune morphology obtained in the simulations. Our simulations suggest that meandering seif dunes constitute a dune type produced by multimodal wind systems and cannot form under (strictly) bimodal wind regimes.

Microwave remote sensing of Saharan ergs and Amazon vegetation

NASA Astrophysics Data System (ADS)

Stephen, Haroon

This dissertation focuses on relating spaceborne microwave data to the geophysical characteristics of the Sahara desert and the Amazon vegetation. Radar and radiometric responses of the Saharan ergs are related to geophysical properties of sand formations and near surface winds. The spatial and temporal variability of the Amazon vegetation is studied using multi-frequency and multi-polarization data. The Sahara desert includes large expanses of sand dunes called ergs that are constantly reshaped by prevailing winds. Radar backscatter (sigma°) measurements observed at various incidence (theta) and azimuth (φ) angles from the NASA Scatterometer (NSCAT), the ERS scatterometer (ESCAT), the SeaWinds scatterometer aboard QuikScat (QSCAT), and the Precipitation Radar (TRMM-PR) aboard the Tropical Rain Monitoring Mission (TRMM) are used to model the sigma° response from sand dunes. Backscatter theta and φ variation depends upon the slopes and orientations of the dune slopes. Sand dunes are modeled as a composite of tilted rough facets, which are characterized by a probability distribution of tilt. The small ripples are modeled as cosinusoidal surface waves that contribute to the return signal at Bragg angles. The sigma° response is high at look angles equal to the mean tilts of the rough facets and is lower elsewhere. The modeled sigma° response is similar to NSCAT and ESCAT observations. sigma° also varies spatially and reflects the spatial inhomogeneity of the sand surface. A model incorporating the sigma° φ-modulation and spatial inhomogeneity is proposed. The maxima of the φ-modulation at theta = 33° reflect the orientation of the slip-sides on the sand surface. These slip-side orientations are consistent with the European Centre for Medium-Range Weather Forecasts wind directions spatially and temporally. Radiometric emissions from the ergs have strong dependence on the surface geometry. The radiometric temperature (Tb) of ergs is modeled as the weighted sum of the Tb from all the composite tilted rough facets. The dual polarization Tb measurements at 19 GHz and 37 GHz from the Special Sensor Microwave Imager (SSM/I) aboard the Defense Meteorological Satellite Program and the Tropical Rainfall Measuring Mission Microwave Imager are used to analyze the radiometric response of erg surfaces and compared to the model results. It is found that longitudinal and transverse dune fields are differentiable based on their polarization difference (DeltaTb) φ-modulation, which reflects type and orientation of dune facets. DeltaT b measurements at 19 GHz and 37 GHz provide consistent results. In the Amazon, sigma° measurements from Seasat A scatterometer (SASS), ESCAT, NSCAT, QSCAT and TRMM-PR; and Tb measurements from SSM/I are used to study the multi-spectral microwave response of vegetation. sigma° versus theta signatures of data combined from scatterometers and the precipitation radar depend upon vegetation density. The multi-frequency signatures of sigma° and Tb provide unique responses for different vegetation densities. sigma° and Tb spatial inhomogeneity is related to spatial geophysical characteristics. Temporal variability of the Amazon basin is studied using C-band ERS data and a Ku-band time series formed by SASS, NSCAT and QSCAT data. Although the central Amazon forest represents an area of very stable radar backscatter measurements, portions of the southern region exhibit backscatter changes over the past two decades.

Downwind effects on an arid dunefield from an evolving urbanised area

NASA Astrophysics Data System (ADS)

Hernández-Calvento, L.; Jackson, D. W. T.; Medina, R.; Hernández-Cordero, A. I.; Cruz, N.; Requejo, S.

2014-12-01

The impacts of urbanised zones on aeolian dynamics are little understood, particularly within arid areas. This study examines the large-scale influence of a growing tourist resort in Gran Canaria Island, Spain, on the sedimentary dynamics of an arid dunefield. Direct downwind effects from the urban area on the dune field surface are modelled for pre-growth and post-growth phases of the urban development. The geomorphological changes observed in the area stretching from the shoreline to the inland transgressive dune field were documented through aerial photographic and LiDAR evidence. Impacts of the urban growth on airflow, as well as those induced by tourists in the upper beach zone (de-vegetation), are examined through analysis of topographic changes. These impacts on the system are shown to have been synergistic in driving the development of a composite dune ridge, formed by the coalescence of smaller dunes into a distinctive aeolian accumulation ridge.

Dune advance into a coastal forest, equatorial Brazil: A subsurface perspective

NASA Astrophysics Data System (ADS)

Buynevich, Ilya V.; Filho, Pedro Walfir M. Souza; Asp, Nils E.

2010-06-01

A large active parabolic dune along the coast of Pará State, northern Brazil, was analyzed using aerial photography and imaged with high-resolution ground-penetrating radar (GPR) to map the subsurface facies architecture and point-source anomalies. Most high-amplitude (8-10 dB) subsurface anomalies are correlated with partially buried mangrove trees along the leading edge (slipface) of the advancing dune. Profiles along a 200-m long basal stoss side of the dune reveal 66 targets, most of which lie below the water table and are thus inaccessible by other methods. Signal amplitudes of point-source anomalies are substantially higher than those associated with the reflections from continuous subsurface features (water table, sedimentary layers). When complemented with exposures and excavations, GPR provides the best means of rapid continuous imaging of the geological record of complex interactions between vegetation and aeolian deposition.

Evaluation of a native vegetation masking technique

NASA Technical Reports Server (NTRS)

Kinsler, M. C.

1984-01-01

A crop masking technique based on Ashburn's vegetative index (AVI) was used to evaluate native vegetation as an indicator of crop moisture condition. A mask of the range areas (native vegetation) was generated for each of thirteen Great Plains LANDSAT MSS sample segments. These masks were compared to the digitized ground truth and accuracies were computed. An analysis of the types of errors indicates a consistency in errors among the segments. The mask represents a simple quick-look technique for evaluating vegetative cover.

Application of topography survey on the green sea turtle (Chelonia mydas) conservation

NASA Astrophysics Data System (ADS)

Fan, Yuan-Yu; Lo, Liu-Chih; Peng, Kuan-Chieh

2017-04-01

Taiwan is located in the Western Pacific monsoon region, typhoon is one of the common natural disasters. Taiwan is hit by typhoons 6 times on average each year, and 2016 have 5. Typhoon not only caused the loss of nature environment in Taiwan but also decreased the endangered species- green sea turtle's breeding success rate. In Wangan island, Penghu, green sea turtle nesting beach's slop is too steep to form the dune cliff, block the way which green sea turtle should nesting above the vegetation line. Nesting under the dune cliff is disturbed easily by the swell from typhoon, Leading to the whole nest was emptied or hatching rate decreased due to water content changed. In order to reduce the threat of typhoon on the green sea turtle, and promote the success of green sea turtle reproduction, we used LiDAR(Light Detection And Ranging) to monitor the topographic change of the green sea turtle nesting habitat and compare the invasion and deposition of the green sea turtle nests before and after the occurrence of typhoons. The results showed that the breeding success rate before the typhoon (2016/09/12) was 93%, which was not affected by the swell. The breeding success rate at the higher position after the typhoon was 95%, and under the dune cliff, 10 nests reproduction failed due to the swell changing the sand layer thickness. The production of dune cliffs is formed by the roots of coastal sand-fixation plants. In the past, the residents collected the coastal plants for fuel, after collecting, sparse vegetation is good to form the flat beach, and to promote green sea turtle nesting on the higher position from the disturbance of typhoon. In the future, to protect the success of green sea turtle's reproduction, should increase the human intervention that disturb the nesting beach's vegetation appropriately, Or cutting the roots directly to reduce the dune cliffs before the nesting season, help the green sea turtle nesting in a higher beach, improve the green sea turtle's breeding success rate.

The impact of fire on sand dune stability: Surface coverage and biomass recovery after fires on Western Australian coastal dune systems from 1988 to 2016

NASA Astrophysics Data System (ADS)

Shumack, Samuel; Hesse, Paul; Turner, Liam

2017-12-01

This study aims to determine the common response of coastal sand dunes in Western Australia (WA) to fire on decadal time-scales, in terms of ecological-geomorphic-climatic interactions to test the hypothesis that fire plays a role in coastal dune destabilisation. Fires are commonly suggested to have contributed to widespread dune reactivation in Australia and globally, a hypothesis that is relatively untested. We used data from the Landsat Thematic Mapper, Enhanced Thematic Mapper Plus, and Operational Land Imager missions to monitor changes in surface coverage on coastal sand dunes in south-west WA after fires. We analysed 31 fire scars from 1988 to 2016 in two Landsat scenes on the west and south coast of WA. Recovery ratios derived from the Normalised Difference Vegetation Index (NDVI) were used to monitor patterns in post-fire biomass and surface cover. Recovery ratios are correlated with indices of burn severity, and meteorological data to investigate relationships. We also used Maximum Likelihood Classification to monitor changes in bare sand area. Results suggest that recovery followed a strongly consistent pattern, and is characterised by rapid vegetation cover re-establishment within six to twelve months. Prior to this, some aeolian activity may have occurred but without substantial surface changes. Initial germination and/or resprouting were followed by steady growth up to seven years, where NDVI typically neared pre-fire values. Some variation in early recovery occurred between the west and south coast, possibly owing to relative proportions of reseeding and resprouting plants. A log regression explained 75% of the recovery pattern (79% on the south coast). Precipitation had some ability to explain recovery up to nine months post-fire (r2 = 0.29 to 0.54). No relationships were observed between estimates of burn severity and recovery. After nine months, the biggest cause of spatial variation in recovery was the pre-fire community composition and related seedbank or resprouting density. Image classification did not identify any new blowout features except where fires were not the primary cause. Results suggest that fires are not presently contributing to the destabilisation of coastal dunes in south-west WA.

Development of a grazing monitoring program for Great Sand Dunes National Park, Colorado

USGS Publications Warehouse

Zeigenfuss, Linda C.; Schoenecker, Kathryn A.

2015-08-07

National parks in the United States face the difficult task of managing natural resources within park boundaries that are influenced to a large degree by historical land uses or by forces outside of the park’s protection and mandate. Among the many challenges faced by parks is management of wildlife populations that occupy larger landscapes than individual park units but that concentrate within park lands both seasonally and opportunistically. Great Sand Dunes National Park and Preserve in south-central Colorado is currently developing an Ungulate Management Plan to address management of elk and bison populations within the park. Execution of the Ungulate Management Plan will require monitoring and assessment of habitat conditions in areas that appear sensitive to ungulate use or heavily used by elk and bison. Several sources of information on the various habitats within the park and their use and response to foraging elk and bison exist from recent and on-going research in Great Sand Dunes National Park and Preserve as well as from studies in other regions of the Intermountain West. All of this data can be used to inform the planning process. This report provides background on vegetation types that make up the primary bison and elk ranges in Great Sand Dunes National Park and Preserve and on the potential effects of ungulate grazing and browsing in these specific vegetation communities (both locally and regionally). The report also provides a review of the elements necessary to develop a long-term monitoring program for Great Sand Dunes National Park and Preserve that addresses both the responses to ungulate herbivory seen in important habitats in the park and the amount and patterns of ungulate habitat use.

Responses of three-dimensional flow to variations in the angle of incident wind and profile form of dunes: Greenwich Dunes, Prince Edward Island, Canada

NASA Astrophysics Data System (ADS)

Walker, Ian J.; Hesp, Patrick A.; Davidson-Arnott, Robin G. D.; Bauer, Bernard O.; Namikas, Steven L.; Ollerhead, Jeff

2009-04-01

This study reports the responses of three-dimensional near-surface airflow over a vegetated foredune to variations in the conditions of incident flow during an 8-h experiment. Two parallel measurement transects were established on morphologically different dune profiles: i) a taller, concave-convex West foredune transect with 0.5-m high, densely vegetated (45%), seaward incipient foredune, and ii) a shorter, concave-straight East foredune transect with lower, sparsely vegetated (14%) seaward incipient foredune. Five stations on each transect from the incipient dune to the crest were equipped with ultrasonic anemometers at 0.6 and 1.65 m height and logged at 1 Hz. Incident conditions were recorded from a 4-m tower over a flat beach. Winds increased from 6 m s - 1 to > 20 m s - 1 and were generally obliquely onshore (ENE, 73°). Three sub-events and the population of 10-minute averages of key properties of flow ( U, W, S, CV U) from all sample locations on the East transect ( n = 235) are examined to identify location- and profile-specific responses over 52° of the incident direction of flow (from 11 to 63° onshore). Topographic steering and forcing cause major deviations in the properties and vectors of near-surface flow from the regional wind. Topographic forcing on the concave-straight dune profile increases wind speed and steadiness toward the crest, with speed-up values to 65% in the backshore. Wind speed and steadiness of flow are least responsive to changes in incident angle in the backshore because of stagnation of flow and are most responsive at the lower stoss under pronounced streamline compression. On the steeper concave-convex profile, speed and steadiness decrease toward the crest because of stagnation of flow at the toe and flow expansion at the slope inflection point on the lower stoss. Net downward vertical velocity occurs over both profiles, increases toward the crest, and reflects enhanced turbulent momentum conveyance toward the surface. All of these flow responses are enhanced with faster speeds of incident flow and/or more onshore winds. Significant onshore steering of near-surface vectors of flow (to 37°) occurs and is greatest closer to the surface and during highly oblique winds (~ 15° onshore). Therefore, even subtle effects of streamline compression and amplification of flow under alongshore conditions effectively steer flow and sand transport toward the dune. As topographic forcing and steering cause significant, three-dimensional deviations in near-surface properties of flow, most regional-scale and/or two-dimensional models of dune process-response dynamics are insufficient for characterizing coastal and desert dune sediment budgets and morphodynamics. In particular, deflection of sand transport vectors with greater fetch distances than those derived from regional winds may occur. Coincident flow, transport and morphological response data are required to better quantitatively model these processes.

Defrosting Polar Dunes--'They Look Like Bushes!'

NASA Technical Reports Server (NTRS)

1999-01-01

'They look like bushes!' That's what almost everyone says when they see the dark features found in pictures taken of sand dunes in the polar regions as they are beginning to defrost after a long, cold winter. It is hard to escape the fact that, at first glance, these images acquired by the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) over both polar regions during the spring and summer seasons, do indeed resemble aerial photographs of sand dune fields on Earth--complete with vegetation growing on and around them! Of course, this is not what the features are, as we describe below and in related picture captions. Still, don't they look like vegetation to you? Shown here are two views of the same MGS MOC image. On the left is the full scene, on the right is an expanded view of a portion of the scene on the left. The bright, smooth surfaces that are dotted with occasional, nearly triangular dark spots are sand dunes covered by winter frost.

The MGS MOC has been used over the past several months (April-August 1999) to monitor dark spots as they form and evolve on polar dune surfaces. The dark spots typically appear first along the lower margins of a dune--similar to the position of bushes and tufts of grass that occur in and among some sand dunes on Earth.

Because the martian air pressure is very low--100 times lower than at Sea Level on Earth--ice on Mars does not melt and become liquid when it warms up. Instead, ice sublimes--that is, it changes directly from solid to gas, just as 'dry ice' does on Earth. As polar dunes emerge from the months-long winter night, and first become exposed to sunlight, the bright winter frost and snow begins to sublime. This process is not uniform everywhere on a dune, but begins in small spots and then over several months it spreads until the entire dune is spotted like a leopard.

The early stages of the defrosting process--as in the picture shown here--give the impression that something is 'growing' on the dunes. The sand underneath the frost is dark, just like basalt beach sand in Hawaii. Once it is exposed to sunlight, the dark sand probably absorbs sunlight and helps speed the defrosting of each sand dune.

This picture was taken by MGS MOC on July 21, 1999. The dunes are located in the south polar region and are expected to be completely defrosted by November or December 1999. North is approximately up, and sunlight illuminates the scene from the upper left. The 500 meter scale bar equals 547 yards; the 300 meter scale is also 328 yards.

Malin Space Science Systems and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission. MSSS operates the camera from its facilities in San Diego, CA. The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, CA and Denver, CO.

Holocene geoarchaeology of the Sixteen Mile Beach barrier dunes in the Western Cape, South Africa

NASA Astrophysics Data System (ADS)

Compton, John S.; Franceschini, Giuliana

2005-01-01

Holocene evolution and human occupation of the Sixteen Mile Beach barrier dunes on the southwest coast of South Africa between Yzerfontein and Saldanha Bay are inferred from the radiocarbon ages of calcareous dune sand, limpet shell ( Patella spp.) manuports and gull-dropped white mussel shells ( Donax serra). A series of coast-parallel dunes have prograded seaward in response to an overall marine regression since the mid-Holocene with dated shell from relict foredunes indicating periods of shoreline progradation that correspond to drops in sea level at around 5900, 4500 and 2400 calibrated years before the present (cal yr B.P.). However, the active foredune, extensively covered by a layer of gull-dropped shell, has migrated 500 m inland by the recycling of eroded dune sand in response to an approximate 1 m sea level rise over the last 700 yr. Manuported limpet shells from relict blowouts on landward vegetated dunes indicate human occupation of coastal dune sites at 6200 and 6000 cal yr B.P. and help to fill the mid-Holocene gap in the regional archaeological record. Coastal midden shells associated with small hearth sites exposed in blowouts on the active foredune are contemporaneous (1600-500 cal yr B.P.) with large midden sites on the western margin of Langebaan Lagoon and suggest an increase in marine resource utilisation associated with the arrival of pastoralism in the Western Cape.

Sediment grain-size characteristics and relevant correlations to the aeolian environment in China's eastern desert region.

PubMed

Zhang, Chunlai; Shen, Yaping; Li, Qing; Jia, Wenru; Li, Jiao; Wang, Xuesong

2018-06-15

To identify characteristics of aeolian activity and the aeolian environment in China's eastern desert region, this study collected surface sediment samples from the main desert and sandy lands in this region: the Hobq Desert and the Mu Us, Otindag, Horqin, and Hulunbuir sandy lands. We analyzed the grain-size characteristics and their relationships to three key environmental indicators: drift potential, the dune mobility index, and vegetation cover. The main sediment components are fine to medium sands, with poor (Hulunbuir) to moderate (all other areas) sorting, of unimodal to bimodal distribution. This suggests that improved sorting is accomplished by the loss of both relatively coarser and finer grains. Since 2000, China's eastern desert region has generally experienced low wind energy environmental conditions, resulting in decreased dune activity. In the Hobq Desert, however, the dry climate and sparse vegetation, in conjunction with the most widely distributed mobile dune area in the eastern desert region, have led to frequent and intense aeolian activity, including wind erosion, sand transport, and deposition, resulting in conditions for good sediment sorting. In the Mu Us, Otindag, and Horqin sandy lands, mosaic distribution has resulted from wind erosion-dominated and deposition-dominated aeolian environments. In the Hulunbuir Sandy Land, high precipitation, low temperatures, and steppe vegetation have resulted in well-developed soils; however, strong winds and flat terrain have created an aeolian environment dominated by wind erosion. Copyright © 2018. Published by Elsevier B.V.

Predaceous ants, beach replenishment, and nest placement by sea turtles.

PubMed

Wetterer, James K; Wood, Lawrence D; Johnson, Chris; Krahe, Holly; Fitchett, Stephanie

2007-10-01

Ants known for attacking and killing hatchling birds and reptiles include the red imported fire ant (Solenopsis invicta Buren), tropical fire ant [Solenopsis geminata (Fabr.)], and little fire ant [Wasmannia auropunctata (Roger)]. We tested whether sea turtle nest placement influenced exposure to predaceous ants. In 2000 and 2001, we surveyed ants along a Florida beach where green turtles (Chelonia mydas L.), leatherbacks (Dermochelys coriacea Vandelli), and loggerheads (Caretta caretta L.) nest. Part of the beach was artificially replenished between our two surveys. As a result, mean beach width experienced by nesting turtles differed greatly between the two nesting seasons. We surveyed 1,548 sea turtle nests (2000: 909 nests; 2001: 639 nests) and found 22 ant species. S. invicta was by far the most common species (on 431 nests); S. geminata and W. auropunctata were uncommon (on 3 and 16 nests, respectively). In 2000, 62.5% of nests had ants present (35.9% with S. invicta), but in 2001, only 30.5% of the nests had ants present (16.4% with S. invicta). Turtle nests closer to dune vegetation had significantly greater exposure to ants. Differences in ant presence on turtle nests between years and among turtle species were closely related to differences in nest placement relative to dune vegetation. Beach replenishment significantly lowered exposure of nests to ants because on the wider beaches turtles nested farther from the dune vegetation. Selective pressures on nesting sea turtles are altered both by the presence of predaceous ants and the practice of beach replenishment.

Uavs to Assess the Evolution of Embryo Dunes

NASA Astrophysics Data System (ADS)

Taddia, Y.; Corbau, C.; Zambello, E.; Russo, V.; Simeoni, U.; Russo, P.; Pellegrinelli, A.

2017-08-01

The balance of a coastal environment is particularly complex: the continuous formation of dunes, their destruction as a result of violent storms, the growth of vegetation and the consequent growth of the dunes themselves are phenomena that significantly affect this balance. This work presents an approach to the long-term monitoring of a complex dune system by means of Unmanned Aerial Vehicles (UAVs). Four different surveys were carried out between November 2015 and November 2016. Aerial photogrammetric data were acquired during flights by a DJI Phantom 2 and a DJI Phantom 3 with cameras in a nadiral arrangement. GNSS receivers in Network Real Time Kinematic (NRTK) mode were used to frame models in the European Terrestrial Reference System. Processing of the captured images consisted in reconstruction of a three-dimensional model using the principles of Structure from Motion (SfM). Particular care was necessary due to the vegetation: filtering of the dense cloud, mainly based on slope detection, was performed to minimize this issue. Final products of the SfM approach were represented by Digital Elevation Models (DEMs) of the sandy coastal environment. Each model was validated by comparison through specially surveyed points. Other analyses were also performed, such as cross sections and computing elevation variations over time. The use of digital photogrammetry by UAVs is particularly reliable: fast acquisition of the images, reconstruction of high-density point clouds, high resolution of final elevation models, as well as flexibility, low cost and accuracy comparable with other available techniques.

Late Pleistocene dune activity in the central Great Plains, USA

USGS Publications Warehouse

Mason, J.A.; Swinehart, J.B.; Hanson, P.R.; Loope, D.B.; Goble, R.J.; Miao, X.; Schmeisser, R.L.

2011-01-01

Stabilized dunes of the central Great Plains, especially the megabarchans and large barchanoid ridges of the Nebraska Sand Hills, provide dramatic evidence of late Quaternary environmental change. Episodic Holocene dune activity in this region is now well-documented, but Late Pleistocene dune mobility has remained poorly documented, despite early interpretations of the Sand Hills dunes as Pleistocene relicts. New optically stimulated luminescence (OSL) ages from drill cores and outcrops provide evidence of Late Pleistocene dune activity at sites distributed across the central Great Plains. In addition, Late Pleistocene eolian sands deposited at 20-25 ka are interbedded with loess south of the Sand Hills. Several of the large dunes sampled in the Sand Hills clearly contain a substantial core of Late Pleistocene sand; thus, they had developed by the Late Pleistocene and were fully mobile at that time, although substantial sand deposition and extensive longitudinal dune construction occurred during the Holocene. Many of the Late Pleistocene OSL ages fall between 17 and 14 ka, but it is likely that these ages represent only the later part of a longer period of dune construction and migration. At several sites, significant Late Pleistocene or Holocene large-dune migration also probably occurred after the time represented by the Pleistocene OSL ages. Sedimentary structures in Late Pleistocene eolian sand and the forms of large dunes potentially constructed in the Late Pleistocene both indicate sand transport dominated by northerly to westerly winds, consistent with Late Pleistocene loess transport directions. Numerical modeling of the climate of the Last Glacial Maximum has often yielded mean monthly surface winds southwest of the Laurentide Ice Sheet that are consistent with this geologic evidence, despite strengthened anticyclonic circulation over the ice sheet. Mobility of large dunes during the Late Pleistocene on the central Great Plains may have been the result of cold, short growing seasons with relatively low precipitation and low atmospheric CO2 that increased plant moisture stress, limiting the ability of vegetation to stabilize active dune sand. The apparent coexistence of large mobile dunes with boreal forest taxa suggests a Late Pleistocene environment with few modern analogs. ?? 2011 Elsevier Ltd.

An optical luminescence chronology for late Pleistocene aeolian activity in the Colombian and Venezuelan Llanos

NASA Astrophysics Data System (ADS)

Carr, Andrew S.; Armitage, Simon J.; Berrío, Juan-Carlos; Bilbao, Bibiana A.; Boom, Arnoud

2016-03-01

The lowland savannas (Llanos) of Colombia and Venezuela are covered by extensive aeolian landforms for which little chronological information exists. We present the first optically stimulated luminescence (OSL) age constraints for dunes in the Llanos Orientales of lowland Colombia and new ages for dunes in the Venezuelan Llanos. The sampled dunes are fully vegetated and show evidence of post-depositional erosion. Ages range from 4.5 ± 0.4 to 66 ± 4 ka, with the majority dating to 27-10 ka (Marine Isotope Stage 2). Some dunes accumulated quickly during the last glacial maximum, although most were active 16-10 ka. Accretion largely ceased after 10 ka. All dunes are elongated downwind from rivers, parallel with dry season winds, and are interpreted as source-bordering features. As they are presently isolated from fluvial sediments by gallery forest it is proposed that activity was associated with a more prolonged dry season, which restricted gallery forest, leading to greater sediment availability on river shorelines. Such variability in dry season duration was potentially mediated by the mean latitude of the ITCZ. The cessation of most dune accretion after ca. 10 ka suggests reduced seasonality and a more northerly ITCZ position, consistent with evidence from the Cariaco Basin.

Vegetation conversion to desirable species along Caltrans rights-of-ways.

DOT National Transportation Integrated Search

2008-12-01

This study evaluates several establishment sequences to determine effective ways to convert existing : annual non-native vegetation to native perennial species. Sustained weed control for several years is : shown to be required for vegetation convers...

Post-storm beach and dune recovery: Implications for barrier island resilience

NASA Astrophysics Data System (ADS)

Houser, Chris; Wernette, Phil; Rentschlar, Elizabeth; Jones, Hannah; Hammond, Brianna; Trimble, Sarah

2015-04-01

The ability of beaches and dunes to recover following an extreme storm is a primary control of barrier island response to sea-level rise and changes in the frequency and/or magnitude of storm surges. Whereas erosion of the beach and dune occurs over hours and days, it can be years to decades before the beach and dune are able to recover to their pre-storm state. As a consequence, there are numerous descriptions of near-instantaneous beach and dune erosion due to storms, the immediate onshore transport of sand, and the initial phases of beach and dune recovery following a storm, but a paucity of data on long-term beach and dune recovery. A combination of previously published data from Galveston Island, Texas and new remotely sensed data from Santa Rosa Island, Florida is used in the present study to quantify the rate of dune recovery for dissipative and intermediate beach types, respectively. Recovery of the dune height and volume on Galveston Island was observed within two years following Hurricane Alicia (1983) and was largely complete within six years of the storm, despite extensive washover. In contrast, the dunes on Santa Rosa Island in Northwest Florida began to recover four years after Hurricane Ivan (2004), and only after the profile approached its pre-storm level and the rate of vegetation recovery (regrowth) was at a maximum. Results show that complete recovery of the largest dunes (in height and volume) will take approximately 10 years on Santa Rosa Island, which suggests that these sections of the island are particularly vulnerable to significant change in island morphology if there is also a change in the frequency and magnitude of storm events. In contrast, the areas of the island with the smallest dunes before Hurricane Ivan exhibited a rapid recovery, but no further growth in profile volume and dune height beyond the pre-storm volume and height, despite continued recovery of the largest dunes to their pre-storm height. A change in storm magnitude and/or frequency is a potential threat to barrier island resilience, particularly for those sections of the island where dune recovery has historically taken the longest time. Further study is required to determine how and why dune recovery varies for the dissipative and intermediate beaches of Galveston Island and Santa Rosa Island, respectively.

Aeolian Processes of the Pismo-Oceano Dune Complex, California

NASA Astrophysics Data System (ADS)

Barrineau, C. P.; Tchakerian, V.; Houser, C.

2012-12-01

The Pismo Dunes are located approximately 250 km northwest of Los Angeles and consist of 90 km2 of transverse, parabolic and paleodunes. The Pismo Dunes are one of the largest dune complexes on the west coast and are the largest remaining south of San Francisco Bay, but despite their size, relatively few process morphology studies have focused on their form and history. Specifically, the dune field includes 12 km2 of actively migrating transverse dune ridges advancing onshore in three distinct phases separated by small depressions easily indentified using a LiDAR-generated elevation model. An early field investigation by Tchakerian (1983) revealed a uniform increase in slip face heights and crestline wavelengths inland with no apparent change in grain size. Measurement of recent aerial imagery shows variable migration rates throughout the dunes and wavelengths between 30 and 100 m closest to the beach, in the second ridge between 50 and 140 m, and from 70 to 250 m furthest inland. During El Niño and La Niña periods, westerly winds advance onshore nearly perpendicular to the crestlines, fueling episodic migration of the dune field. It is hypothesized that particularly strong ENSO periods may have led to the development of distinct dune phases with separating depressions and the development of defects along the dune crest. Defects associated with the wakes of incipient vegetation and inter-dune depressions are conspicuous and widespread, though localized and variable through time and space. Aerial imagery taken in September 1994 shows a wider, more even distribution of defects across the dune field than currently visible. The signal is, however, complicated by the closure of the dune field to oversand vehicles in 1982. The closure of much of the complex to vehicular traffic in 1982 may play a role, as Tchakerian's crestline wavelength measurements were far smaller than those obtained for this study while maintaining a likewise increase between phases. At a decadal scale, excessive vehicular traffic may have impeded the transition of emergent, defect-ridden dune forms into mature transverse ridges. Despite the astounding lack to studies focusing on the Pismo Dunes, the complex presents multiple opportunities for inquiry regarding climatic control on dune field evolution, defect law and complex landform pattern development, and long-term anthropogenic alteration of coastal process morphology.

Higher ant diversity in native vegetation than in stands of the invasive arundo, Arundo donax L., along the Rio Grande basin in Texas, U.S.A.

USDA-ARS?s Scientific Manuscript database

Ants collected in pitfall traps were identified and compared between native vegetation and monoculture stands of arundo, Arundo donax L., monthly at 10 locations for a year. A total of 82,752 ants representing 28 genera and 76 species were collected. More ants were collected in the native vegetation...

Australian Pine, Casuarina equisetifolia L. Management Plan for Florida

USDA-ARS?s Scientific Manuscript database

Australian pine (Casuarina equisetifolia) is a fast growing tree native to Australia, Southeast Asia, India, Bangladesh and the Pacific Islands that has been introduced to tropical areas throughout the world as an ornamental; to stabilize sand dunes; to form windbreaks around canals, roads, houses, ...

VEGETATION CHARACTERIZATION OF THREE CONTRASTING RIPARIAN SITES, WILLAMETTE VALLEY, OR

EPA Science Inventory

Much of the native riparian vegetation of the Willamette Valley, Oregon, has been replaced with agricultural crops or invasive non-native plant species. Detailed information about current Willamette Valley riparian vegetation is generally lacking. Plant species composition data...

Promoting Native Vegetation in Medusahead Infestations

USDA-ARS?s Scientific Manuscript database

Restoring medusahead-infested native communities may be most successful if there is enough remnant native vegetation to eliminate the need for revegetation efforts. Prescribed burning followed by imazapic (Plateau®1) application provided the best control of medusahead and resulted in the greatest i...

Invasive non-native species' provision of refugia for endangered native species.

PubMed

Chiba, Satoshi

2010-08-01

The influence of non-native species on native ecosystems is not predicted easily when interspecific interactions are complex. Species removal can result in unexpected and undesired changes to other ecosystem components. I examined whether invasive non-native species may both harm and provide refugia for endangered native species. The invasive non-native plant Casuarina stricta has damaged the native flora and caused decline of the snail fauna on the Ogasawara Islands, Japan. On Anijima in 2006 and 2009, I examined endemic land snails in the genus Ogasawarana. I compared the density of live specimens and frequency of predation scars (from black rats [Rattus rattus]) on empty shells in native vegetation and Casuarina forests. The density of land snails was greater in native vegetation than in Casuarina forests in 2006. Nevertheless, radical declines in the density of land snails occurred in native vegetation since 2006 in association with increasing predation by black rats. In contrast, abundance of Ogasawarana did not decline in the Casuarina forest, where shells with predation scars from rats were rare. As a result, the density of snails was greater in the Casuarina forest than in native vegetation. Removal of Casuarina was associated with an increased proportion of shells with predation scars from rats and a decrease in the density of Ogasawarana. The thick and dense litter of Casuarina appears to provide refugia for native land snails by protecting them from predation by rats; thus, eradication of rats should precede eradication of Casuarina. Adaptive strategies, particularly those that consider the removal order of non-native species, are crucial to minimizing the unintended effects of eradication on native species. In addition, my results suggested that in some cases a given non-native species can be used to mitigate the impacts of other non-native species on native species.

Integration of Multi-sensor Data for Desertification Monitoring

NASA Astrophysics Data System (ADS)

Lin, S.; Kim, J.

2010-12-01

The desert area has been rapidly expanding globally due to reasons such as climate change, uninhibited human activities, etc. The continuous desertification has seriously affected in (and near) desert area all over the world. As sand dune activity has been recognised as an essential indicator of desertification (it is the signature and the consequence of desertification), an accurate monitoring of desert dune movement hence becomes crucial for understanding and modelling the progress of desertification. In order to determine dune’s moving speed and tendency, also to understand the propagation occurring in transition region between desert and soil rich area, a monitoring system applying multi-temporal and multi-sensor remote sensed data are proposed and implemented. Remote sensed data involved in the monitoring scheme include space-borne optical image, Synthetic Aperture Radar (SAR) data, multi- and hyper-spectral image, and terrestrial close range image. In order to determine the movement of dunes, a reference terrain surface is required. To this end, a digital terrain model (DTM) covering the test site is firstly produced using high resolution optical stereo satellite images. Subsequently, ERS-1/2 SAR imagery are employed as another resource for dune field observation. Through the interferometric SAR (InSAR) technique combining with image-based stereo DTM, the surface displacements are obtained. From which the movement and speed of the dunes can be determined. To understand the effect of desertification combating activities, the correlation between dune activities and the landcover change is also an important issue to be covered in the monitoring scheme. The task is accomplished by tracing soil and vegetation canopy variation with the multi and hyper spectral image analysis using Hyperion and Ali imagery derived from Earth Observation Mission 1 (EO-1). As a result, the correlation between the soil restorations, expanding of vegetation canopy and the ceasing of dune activities can be clearly revealed. For the very detailed measurement, a terrestrial system applying close range photogrammetry will be set up in the test sites to acquire sequential images and used to generate 4D model of the dunes in future. Finally, all the outputs from the multi-sensor data will be crossly verified and compiled to model the desertification process and the consequences. A desertification combating activity which is performed by Korea-China NGO alliance has been conducted in Qubuqi desert in Nei Mongol, China. The method and system proposed above will be established and applied to monitor the dune mobility occurring in this area. The results are expected to be of great value to demonstrate the first case of remote sensing monitoring over the combat desertification activities.

Quantifying energy and water fluxes in dry dune ecosystems of the Netherlands

NASA Astrophysics Data System (ADS)

Voortman, B. R.; Bartholomeus, R. P.; van der Zee, S. E. A. T. M.; Bierkens, M. F. P.; Witte, J. P. M.

2015-09-01

Coastal and inland dunes provide various ecosystem services that are related to groundwater, such as drinking water production and biodiversity. To manage groundwater in a sustainable manner, knowledge of actual evapotranspiration (ETa) for the various land covers in dunes is essential. Aiming at improving the parameterization of dune vegetation in hydrometeorological models, this study explores the magnitude of energy and water fluxes in an inland dune ecosystem in the Netherlands. Hydrometeorological measurements were used to parameterize the Penman-Monteith evapotranspiration model for four different surfaces: bare sand, moss, grass and heather. We found that the net longwave radiation (Rnl) was the largest energy flux for most surfaces during daytime. However, modeling this flux by a calibrated FAO-56 Rnl model for each surface and for hourly time steps was unsuccessful. Our Rnl model, with a novel submodel using solar elevation angle and air temperature to describe the diurnal pattern in radiative surface temperature, improved Rnl simulations considerably. Model simulations of evaporation from moss surfaces showed that the modulating effect of mosses on the water balance is species-dependent. We demonstrate that dense moss carpets (Campylopus introflexus) evaporate more (5 %, +14 mm) than bare sand (total of 258 mm in 2013), while more open-structured mosses (Hypnum cupressiforme) evaporate less (-30 %, -76 mm) than bare sand. Additionally, we found that a drought event in the summer of 2013 showed a pronounced delayed signal on lysimeter measurements of ETa for the grass and heather surfaces, respectively. Due to the desiccation of leaves after the drought event, and their feedback on the surface resistance, the potential evapotranspiration in the year 2013 dropped by 9 % (-37 mm) and 10 % (-61 mm) for the grass and heather surfaces, respectively, which subsequently led to lowered ETa of 8 % (-29 mm) and 7 % (-29 mm). These feedbacks are of importance for water resources, especially during a changing climate with an increasing number of drought days. Therefore, such feedbacks need to be integrated into a coupled plant physiological and hydrometeorological model to accurately simulate ETa. In addition, our study showed that groundwater recharge in dunes can be increased considerably by promoting moss vegetation, especially of open-structured moss species.

Seasonal geomorphic processes and rates of sand movement at Mount Baldy dune in Indiana, USA

NASA Astrophysics Data System (ADS)

Kilibarda, Zoran; Kilibarda, Vesna

2016-12-01

Winds are very strong, frequent, and have high energy (annual DP ∼800 VU) along the southern shores of Lake Michigan, allowing the coexistence of fixed and active dunes. Six years (2007-13) of monitoring Mount Baldy in the Indiana Dunes National Lakeshore reveals that this is the most active coastal dune in the Great Lakes region. This paper documents aeolian processes and changes in the dune's morphology that occur temporarily, following storms, or seasonally, due to weather (climate) variations. Most of the sand transport in this area takes place during strong storms with gale force (>17.5 m/s) winds, which occur in the autumn and winter months. A single storm, such as the October 28-31, 2013 event, can contribute 25% of the annual sand transport and dune movement inland. In its most active year (June 1, 2011 through May 31, 2012), Mount Baldy moved inland on average 4.34 m, with a maximum of 6.52 m along the blowout's axis (155° azimuth). During this particularly active season, there were six storms with sustained gale force winds, winter air temperatures were warmer than average, and shelf ice on Lake Michigan lasted only one day. The dune is least active during the summer season, when the winds are weakest. The late fall and winter winds are the strongest. But in a typical year, most of the dune's advance inland takes place during the spring thaw when sand is released from over-steepened and lumpy slip face, allowing it to avalanche to the toe of the slip face. However, with a warming air temperatures, a reduction in the duration of winter shelf ice, and rising Lake Michigan levels, the annual rates of sand transport and dune movement may increase. The recent Mount Baldy management strategy, which includes planting vegetation and installing wind barriers on the dune's stoss side in an effort to fix the dune and stop its further movement inland, may potentially cause the destruction of the mobile sand, open dune habitat, resulting in the extinction of rare plants, insects, lizards, birds, and mammals.

Effects of soil characteristics, allelopathy and frugivory on establishment of the invasive plant Carpobrotus edulis and a co-occurring native, Malcolmia littorea.

PubMed

Novoa, Ana; González, Luís; Moravcová, Lenka; Pyšek, Petr

2012-01-01

The species Carpobrotus edulis, native to South Africa, is one of the major plant invaders of Mediterranean coastal ecosystems around the world. Invasion by C. edulis exerts a great impact on coastal habitats. The low number of native species in invaded communities points to the possible existence of mechanisms suppressing their germination. In this study we assessed whether soil factors, endozoochory, competition and allelopathic effects of the invader affect its own early establishment and that of the native species Malcolmia littorea. We used laboratory solutions representing different chemical composition and moisture of the soil, herbivore feeding assays to simulate seed scarification and rainwater solutions to account for the effect of differently aged C. edulis litter. We show that unlike that of the native species, germination and early growth of C. edulis was not constrained by low moisture. The establishment of C. edulis, in terms of germination and early growth, was increased by scarification of seeds following passage through the European rabbit intestines; the rabbits therefore may have potential implications for plant establishment. There was no competition between C. edulis and M. littorea. The litter of the invasive C. edulis, which remains on the soil surface for several years, releases allelopathic substances that suppress the native plant germination process and early root growth. The invasive species exhibits features that likely make it a better colonizer of sand dunes than the co-occurring native species. Allelopathic effects, ability to establish in drier microsites and efficient scarification by rabbits are among the mechanisms allowing C. edulis to invade. The results help to explain the failure of removal projects that have been carried out in order to restore dunes invaded by C. edulis, and the long-lasting effects of C. edulis litter need to be taken into account in future restoration projects.

Effects of Soil Characteristics, Allelopathy and Frugivory on Establishment of the Invasive Plant Carpobrotus edulis and a Co-Occuring Native, Malcolmia littorea

PubMed Central

Novoa, Ana; González, Luís; Moravcová, Lenka; Pyšek, Petr

2012-01-01

Background The species Carpobrotus edulis, native to South Africa, is one of the major plant invaders of Mediterranean coastal ecosystems around the world. Invasion by C. edulis exerts a great impact on coastal habitats. The low number of native species in invaded communities points to the possible existence of mechanisms suppressing their germination. In this study we assessed whether soil factors, endozoochory, competition and allelopathic effects of the invader affect its own early establishment and that of the native species Malcolmia littorea. We used laboratory solutions representing different chemical composition and moisture of the soil, herbivore feeding assays to simulate seed scarification and rainwater solutions to account for the effect of differently aged C. edulis litter. Principal Findings We show that unlike that of the native species, germination and early growth of C. edulis was not constrained by low moisture. The establishment of C. edulis, in terms of germination and early growth, was increased by scarification of seeds following passage through the European rabbit intestines; the rabbits therefore may have potential implications for plant establishment. There was no competition between C. edulis and M. littorea. The litter of the invasive C. edulis, which remains on the soil surface for several years, releases allelopathic substances that suppress the native plant germination process and early root growth. Conclusions The invasive species exhibits features that likely make it a better colonizer of sand dunes than the co-occurring native species. Allelopathic effects, ability to establish in drier microsites and efficient scarification by rabbits are among the mechanisms allowing C. edulis to invade. The results help to explain the failure of removal projects that have been carried out in order to restore dunes invaded by C. edulis, and the long-lasting effects of C. edulis litter need to be taken into account in future restoration projects. PMID:23300885

Sand dune tracking from satellite laser altimetry

NASA Astrophysics Data System (ADS)

Dabboor, Mohammed

Substantial problems arise from sand movement in arid and semi-arid countries. Sand poses a threat to infrastructure, agricultural and urban areas. These issues are caused by the encroachment of sand on roads and railway tracks, farmland, towns and villages, and airports, to name a few. Sand movement highly depends on geomorphology including vegetation cover, shape and height of the terrain, and grain size of the sand. However, wind direction and speed are the most important factors that affect efficient sand movement. The direction of the movement depends on the main direction of the wind, but it has been shown that a minimum wind speed is required, e.g. wind gusts, to initiate sand transport. This fact prevents a simple calculation of sand transport from conventional wind data as wind records rarely contain sub-minute intervals masking out any wind gusts. An alternative of predicting sand transport is the direct observation of sand advance by in situ measurements or via satellite. Until recently, satellite imagery was the only means to compare dune shape and position for predicting dune migration over several years. In 2003, the NASA laser altimetry mission ICESat became operational and monitors elevations over all surface types including sand dunes with an accuracy of about 10-20 cm. In this study, ICESat observations from repeat tracks (tracks overlapping eachother within 50 m) are used to derive sand dune advance and direction. The method employs a correlation of the elevation profiles over several dunes and was sucessfully validated with synthetic data. The accuracy of this method is 5 meters of dune advance. One of the most active areas exhibiting sand and dune movement is the area of the Arabian Peninsula. Approximately one-third of the Arabian Peninsula is covered by sand dunes. Different wind regimes (Shamal, Kaus) cause sand dune movement in the selected study area in the eastern part of the Arabian Peninsula between 20-25 degrees North and 45-55 degrees East. Two different dune types can be distinguised which exhibit a 6 m and 26 m average dune advance over a 6 months time period. Wind speed/direction data and the observed dune advance agree well and indicate that dune tracking from space is a viable alternative to in situ or model data.

[Nutrient contents and microbial populations of aeolian sandy soil in Sanjiangyuan region of Qinghai Province].

PubMed

Lin, Chao-feng; Chen, Zhan-quan; Xue, Quan-hong; Lai, Hang-xian; Chen, Lai-sheng; Zhang, Deng-shan

2007-01-01

Sanjiangyuan region (the headstream of three rivers) in Qinghai Province of China is the highest and largest inland alpine wetland in the world. The study on the nutrient contents and microbial populations of aeolian sandy soils in this region showed that soil organic matter content increased with the evolution of aeolian sand dunes from un-stabilized to stabilized state, being 5.9 and 3.8 times higher in stabilized sand dune than in mobile and semi-stabilized sand dunes, respectively. Soil nitrogen and phosphorus contents increased in line with the amount of organic matter, while potassium content and pH value varied slightly. The microbial populations changed markedly with the development of vegetation, fixing of mobile sand, and increase of soil nutrients. The quantities of soil bacteria, fungi and actinomycetes were 4.0 and 2.8 times, 19.6 and 6.3 times, and 12.4 and 2.6 times higher in stabilized and semi-stabilized sand dunes than in mobile sand dune, respectively, indicating that soil microbial bio-diversity was increased with the evolution of aeolian sand dunes from mobile to stabilized state. In addition, the quantities of soil microbes were closely correlated with the contents of soil organic matter, total nitrogen, and available nitrogen and phosphorus, but not correlated with soil total phosphorus, total and available potassium, or pH value.

Temporal and spatial patterns of Holocene dune activity on the Great Plains of North America: megadroughts and climate links

NASA Astrophysics Data System (ADS)

Forman, Steven L.; Oglesby, Robert; Webb, Robert S.

2001-05-01

The Holocene record of eolian sand and loess deposition is reviewed for numerous presently stabilized dune fields on the Great Plains of North America. Dune field activity reflects decade-to-century-scale dominance of drought that exceeded historic conditions, with a growing season deficit of precipitation >25%. The largest dune fields, the Nebraska Sand Hills and ergs in eastern Colorado, Kansas and the Southern High Plains showed peak activity sometime between ca. 7 and 5 cal. ka. Loess deposition between ca. 10 and 4 cal. ka also signifies widespread aridity. Most dune fields exhibit evidence for one or more reactivation events sometime in the past 2 cal. ka; a number of localities register two events post 1 cal. ka, the latest potentially after 1400 AD. However, there is not a clear association of the latest dune remobilization events with up to 13 droughts in the past 2 cal. ka identified in dendroclimatic and lacustrine records. Periods of persistent drought are associated with a La Niña-dominated climate state, with cooling of sea surface temperatures in the tropical Pacific Ocean and later of the tropical Atlantic Ocean and the Gulf of Mexico that significantly weakens cyclogenesis over central North America. As drought proceeds, reduced soil moisture and vegetation cover would lessen evaporative cooling and increase surface temperatures. These surface changes strengthen the eastward expansion of a high-pressure ridge aloft and shift the jet stream northward, further enhancing continent-wide drought. Uncertainty persists if dune fields will reactivate in the future at a scale similar to the Holocene because of widespread irrigation, the lack of migratory bison herds, and the suppression of prairie fires, all of which enhance stabilization of dune fields in the Great Plains.

Beyond habitat structure: Landscape heterogeneity explains the monito del monte (Dromiciops gliroides) occurrence and behavior at habitats dominated by exotic trees.

PubMed

Salazar, Daniela A; Fontúrbel, Francisco E

2016-09-01

Habitat structure determines species occurrence and behavior. However, human activities are altering natural habitat structure, potentially hampering native species due to the loss of nesting cavities, shelter or movement pathways. The South American temperate rainforest is experiencing an accelerated loss and degradation, compromising the persistence of many native species, and particularly of the monito del monte (Dromiciops gliroides Thomas, 1894), an arboreal marsupial that plays a key role as seed disperser. Aiming to compare 2 contrasting habitats (a native forest and a transformed habitat composed of abandoned Eucalyptus plantations and native understory vegetation), we assessed D. gliroides' occurrence using camera traps and measured several structural features (e.g. shrub and bamboo cover, deadwood presence, moss abundance) at 100 camera locations. Complementarily, we used radio telemetry to assess its spatial ecology, aiming to depict a more complete scenario. Moss abundance was the only significant variable explaining D. gliroides occurrence between habitats, and no structural variable explained its occurrence at the transformed habitat. There were no differences in home range, core area or inter-individual overlapping. In the transformed habitats, tracked individuals used native and Eucalyptus-associated vegetation types according to their abundance. Diurnal locations (and, hence, nesting sites) were located exclusively in native vegetation. The landscape heterogeneity resulting from the vicinity of native and Eucalyptus-associated vegetation likely explains D. gliroides occurrence better than the habitat structure itself, as it may be use Eucalyptus-associated vegetation for feeding purposes but depend on native vegetation for nesting. © 2016 International Society of Zoological Sciences, Institute of Zoology/Chinese Academy of Sciences and John Wiley & Sons Australia, Ltd.

Environmental Attitudes Semantic Differential.

ERIC Educational Resources Information Center

Mehne, Paul R.; Goulard, Cary J.

This booklet is an evaluation instrument which utilizes semantic differential data to assess environmental attitudes. Twelve concepts are included: regulated access to beaches, urban planning, dune vegetation, wetlands, future cities, reclaiming wetlands for building development, city parks, commercial development of beaches, existing cities,…

Quantifying Fractional Ground Cover on the Climate Sensitive High Plains Using AVIRIS and Landsat TM Data

NASA Technical Reports Server (NTRS)

Warner, Amanda Susan

2002-01-01

The High Plains is an economically important and climatologically sensitive region of the United States and Canada. The High Plains contain 100,000 sq km of Holocene sand dunes and sand sheets that are currently stabilized by natural vegetation. Droughts and the larger threat of global warming are climate phenomena that could cause depletion of natural vegetation and make this region susceptible to sand dune reactivation. This thesis is part of a larger study that is assessing the effect of climate variability on the natural vegetation that covers the High Plains using Landsat 5 and Landsat 7 data. The question this thesis addresses is how can fractional vegetation cover be mapped with the Landsat instruments using linear spectral mixture analysis and to what accuracy. The method discussed in this thesis made use of a high spatial and spectral resolution sensor called AVIRIS (Airborne Visible and Infrared Imaging Spectrometer) and field measurements to test vegetation mapping in three Landsat 7 sub-scenes. Near-simultaneous AVIRIS images near Ft. Morgan, Colorado and near Logan, New Mexico were acquired on July 10, 1999 and September 30, 1999, respectively. The AVIRIS flights preceded Landsat 7 overpasses by approximately one hour. These data provided the opportunity to test spectral mixture algorithms with AVIRIS and to use these data to constrain the multispectral mixed pixels of Landsat 7. The comparisons of mixture analysis between the two instruments showed that AVIRIS endmembers can be used to unmix Landsat 7 data with good estimates of soil cover, and reasonable estimates of non-photosynthetic vegetation and green vegetation. Landsat 7 derived image endmembers correlate with AVIRIS fractions, but the error is relatively large and does not give a precise estimate of cover.

Canyon grassland vegetation changes following fire in northern Idaho

Treesearch

Corey L. Gucker; Stephen C. Bunting

2011-01-01

Native and nonnative vegetation mosaics are common in western rangelands. If land managers could better predict changes in the abundance of native and nonnative species following disturbances, maintenance of native plant cover and diversity may be improved. In August 2000, during suppression of a wildfire near Lewiston, Idaho, a backing fire burned canyon grassland...

Determination of semi-arid landscape endmembers and seasonal trends using convex geometry spectral unmixing techniques

NASA Technical Reports Server (NTRS)

Yuhas, Roberta H.; Boardman, Joseph W.; Goetz, Alexander F. H.

1993-01-01

Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) data were acquired during three consecutive growing seasons (26 September 1989, 22 March 1990, and 7 August 1990) over an area of the High Plains east of Greeley, Colorado (40 deg 20 min N and 104 deg 16 min W). A repeat visit to assess vegetation at its peak growth was flown on 6 June 1993. This region contains extensive eolian deposits in the form of stabilized dune complexes (small scale parabolic dunes superimposed on large scale longitudinal and parabolic dunes). Due to the dunes' large scale (2-10 km) and low relief (1-5 m), the scaling and morphological relationships that contribute to the evolution of this landscape are nearly impossible to understand without the use of remote sensing. Additionally, this area and regions similarly situated could be the first to experience the effects caused by global climate change. During the past 10,000 years there were at least four periods of extensive sand activity due to climate change, followed by periods of landscape stability, as shown in the stratigraphic record of this area.

An invasive wetland grass primes deep soil carbon pools.

PubMed

Bernal, Blanca; Megonigal, J Patrick; Mozdzer, Thomas J

2017-05-01

Understanding the processes that control deep soil carbon (C) dynamics and accumulation is of key importance, given the relevance of soil organic matter (SOM) as a vast C pool and climate change buffer. Methodological constraints of measuring SOM decomposition in the field prevent the addressing of real-time rhizosphere effects that regulate nutrient cycling and SOM decomposition. An invasive lineage of Phragmites australis roots deeper than native vegetation (Schoenoplectus americanus and Spartina patens) in coastal marshes of North America and has potential to dramatically alter C cycling and accumulation in these ecosystems. To evaluate the effect of deep rooting on SOM decomposition we designed a mesocosm experiment that differentiates between plant-derived, surface SOM-derived (0-40 cm, active root zone of native marsh vegetation), and deep SOM-derived mineralization (40-80 cm, below active root zone of native vegetation). We found invasive P. australis allocated the highest proportion of roots in deeper soils, differing significantly from the native vegetation in root : shoot ratio and belowground biomass allocation. About half of the CO 2 produced came from plant tissue mineralization in invasive and native communities; the rest of the CO 2 was produced from SOM mineralization (priming). Under P. australis, 35% of the CO 2 was produced from deep SOM priming and 9% from surface SOM. In the native community, 9% was produced from deep SOM priming and 44% from surface SOM. SOM priming in the native community was proportional to belowground biomass, while P. australis showed much higher priming with less belowground biomass. If P. australis deep rooting favors the decomposition of deep-buried SOM accumulated under native vegetation, P. australis invasion into a wetland could fundamentally change SOM dynamics and lead to the loss of the C pool that was previously sequestered at depth under the native vegetation, thereby altering the function of a wetland as a long-term C sink. © 2016 John Wiley & Sons Ltd.

Nature Photography - Vultures

NASA Image and Video Library

2017-01-30

A vulture watches from a perch on sandy dunes at NASA's Kennedy Space Center in Florida. The center shares a border with the Merritt Island National Wildlife Refuge. The bird is one of more than 330 native and migratory bird species, 25 mammals, 117 fishes and 65 amphibians and reptiles that call Kennedy and the wildlife refuge home.

Mapping areas invaded by Prosopis juliflora in Somaliland on Landsat 8 imagery

NASA Astrophysics Data System (ADS)

Rembold, Felix; Leonardi, Ugo; Ng, Wai-Tim; Gadain, Hussein; Meroni, Michele; Atzberger, Clement

2015-10-01

Prosopis juliflora is a fast growing tree species originating from South and Central America with a high invasion potential in semi-arid areas around the globe. It was introduced to East Africa for the stabilization of dune systems and for providing fuel wood after prolonged droughts and deforestation in the 1970s and 1980s. In many dry lands in East Africa the species has expanded rapidly and has become challenging to control. The species generally starts its colonization on deep soils with high water availability while in later stages or on poorer soils, its thorny thickets expand into drier grasslands and rangelands. Abandoned or low input farmland is also highly susceptible for invasion as P. juliflora has competitive advantages to native species and is extremely drought tolerant. In this work we describe a rapid approach to detect and map P. juliflora invasion at country level for the whole of Somaliland. Field observations were used to delineate training sites for a supervised classification of Landsat 8 imagery collected during the driest period of the year (i.e., from late February to early April). The choice of such a period allowed to maximise the spectral differences between P. juliflora and other species present in the area, as P. juliflora tends to maintain a higher vigour and canopy water content than native vegetation, when exposed to water stress. The results of our classification map the current status of invasion of Prosopis in Somaliland showing where the plant is invading natural vegetation or agricultural areas. These results have been verified for two spatial subsets of the whole study area with very high resolution (VHR) imagery, proving that Landsat 8 imagery is highly adequate to map P. juliflora. The produced map represents a baseline for understanding spatial distribution of P. juliflora across Somaliland but also for change detection and monitoring of long term dynamics in support to P. juliflora management and control activities.

Mid-Holocene stabilization of the Karakum and Kyzylkum sand seas, central Asia - evidence from OSL ages

NASA Astrophysics Data System (ADS)

Maman, Shimrit; Tsoar, Haim; Blumberg, Dan G.; Porat, Naomi

2013-04-01

Sand seas (ergs) are large areas of deserts covered by wind-swept sand with varying degrees of vegetation cover. The Kyzylkum and Karakum ergs have accumulated in the Turan basin, northwest of the Hindu Kush range, and span from south Turkmenistan to the Syrdarya River in Kazakhstan. These ergs are dissected by the Amudarya River; To the north lies the Kyzylkum (red sands) and to the south the Karakum (black sands). This area is understudied, and little information has been published regarding the sands stabilization processes and deposition ages. This research focuses on identifying and mapping the ergs of Central Asia and analyzing the climate factors that set the dunes into motion and that stabilized them. A variety of spaceborne imagery with varying spectral and spatial resolutions was used. These images provide the basis for mapping sand distribution, dune forms, and vegetation cover. Wilson (1973) defined these ergs as active based on precipitation. Our results show that they are mostly stabilized, with an estimated area of ~260,000 sq. Km for Kara-Kum , and ~195,500 sq. Km for the Kyzyl-Kum . Meteorological analysis of wind and precipitation data indicate a low wind energy environment (DP<200) and sufficient rainfall (>100 mm) to which is essential for vegetation cover. We present the first optically stimulated luminescence (OSL) ages from the upper meter of 14 exposed sections from both ergs. The age of the sand samples was determined as ~Mid-Holocene by OSL, which provides an insight into past climate characteristics. These ages indicate extensive sand and dune stabilization during the Mid-Holocene. GIS analysis was performed in parallel with field work to validate and verify the results. The OSL ages, coupled with a compilation of regional palaeoclimatic data, corroborate and reinforce the previously proposed Mid-Holocene Liavliakan phase, known to reflect a warmer, wetter, less windy climate than persists today and that resulted in dune stabilization around Mid-Holocene. This study emphasizes the importance of regional climatic control on aeolian activity and is the first to show when these vast sand seas were stabilized.

Changes in wind erosion over a 25-year restoration chronosequence on the south edge of the Tengger Desert, China: implications for preventing desertification.

PubMed

Ma, Quanlin; Fehmi, Jeffrey S; Zhang, Dekui; Fan, Baoli; Chen, Fang

2017-08-23

Wind erosion is a primary cause of desertification as well as being a serious ecological problem in arid and semi-arid areas across the world. To determine mechanisms for restoring desertified lands, an unrestored shifting sand dune and three formerly shifting sand dunes (desertified lands) that had been enclosed and afforested for 5, 15, and 25 years were selected for evaluation on the south edge of the Tengger Desert, China. Based on sampling heights between 0.2 and 3 m, the critical threshold average wind speed was 6.5 m s -1 at 2 m where the sand transport rate was reduced from 285.9 kg m -2  h -1 on the unrestored dunes to 9.1 and 1.8 kg m -2  h -1 on the sites afforested and enclosed for 5 and 15 years, respectively. The percentage of wind eroded area was reduced from 99.9% on the unrestored dune to 94.5, 9.0, and 0.5% on the sites afforested and enclosed for 5, 15, and 25 years, respectively. Wind erosion was effectively reduced after 15 years. Although there were different driving factors for wind erosion mitigation on the different restoration stages, an increase in the vegetation cover, surface roughness, soil shear strength, soil clay content, organic matter, and reduction in the near-surface wind speed were the primary variables associated with the restoration chronosequence. We conclude that reducing the wind speed and developing a biological crust through vegetation restoration were the critical components for restoration of desertified land.

Responses of soil fungal community to the sandy grassland restoration in Horqin Sandy Land, northern China.

PubMed

Wang, Shao-Kun; Zuo, Xiao-An; Zhao, Xue-Yong; Li, Yu-Qiang; Zhou, Xin; Lv, Peng; Luo, Yong-Qing; Yun, Jian-Ying

2016-01-01

Sandy grassland restoration is a vital process including re-structure of soils, restoration of vegetation, and soil functioning in arid and semi-arid regions. Soil fungal community is a complex and critical component of soil functioning and ecological balance due to its roles in organic matter decomposition and nutrient cycling following sandy grassland restoration. In this study, soil fungal community and its relationship with environmental factors were examined along a habitat gradient of sandy grassland restoration: mobile dunes (MD), semi-fixed dunes (SFD), fixed dunes (FD), and grassland (G). It was found that species abundance, richness, and diversity of fungal community increased along with the sandy grassland restoration. The sequences analysis suggested that most of the fungal species (68.4 %) belonged to the phylum of Ascomycota. The three predominant fungal species were Pleospora herbarum, Wickerhamomyces anomalus, and Deconica Montana, accounting for more than one fourth of all the 38 species. Geranomyces variabilis was the subdominant species in MD, Pseudogymnoascus destructans and Mortierella alpine were the subdominant species in SFD, and P. destructans and Fungi incertae sedis were the dominant species in FD and G. The result from redundancy analysis (RDA) and stepwise regression analysis indicated that the vegetation characteristics and soil properties explain a significant proportion of the variation in the fungal community, and aboveground biomass and C:N ratio are the key factors to determine soil fungal community composition during sandy grassland restoration. It was suggested that the restoration of sandy grassland combined with vegetation and soil properties improved the soil fungal diversity. Also, the dominant species was found to be alternative following the restoration of sandy grassland ecosystems.

Vegetation response after post-fire mulching and native grass seeding

Treesearch

Penelope Morgan; Marshell Moy; Christine A. Droske; Leigh B. Lentile; Sarah A. Lewis; Peter R. Robichaud; Andrew T. Hudak

2014-01-01

Post-fire mulch and seeding treatments, often applied on steep, severely burned slopes immediately after large wildfires, are meant to reduce the potential of erosion and establishment of invasive plants, especially non-native plants, that could threaten values at risk. However, the effects of these treatments on native vegetation response post fire are little studied...

Earth Observations taken by Expedition 30 crewmember

NASA Image and Video Library

2012-01-19

ISS030-E-059398 (19 Jan. 2012) --- Lake Fitri, Chad is featured in this image photographed by an Expedition 30 crew member on the International Space Station. Lake Fitri is an endorheic, or terminal lake in a desert basin in the southern Sahara Desert. Muddy yellow-brown water marks the center of the depression (center), with a ring of dark brown muds and burnt vegetation on the exposed lake floor to the north. The lake shoreline supports a thin line of reed and floating grass vegetation which appears as dark green in the image. Deserts have so little rainfall that many rivers cannot reach the sea, but end at local low points where they form lakes. Here the usually dry Wadi Batha empties into Lake Fitri. Over time, water flow in Wadi Batha has created a large delta, which occupies the entire top left third of the image—a sense of scale is given by the 23–kilometer length of the lake. The lake has been designated under the Ramsar Convention as a wetland of international importance. Other features visible in the image reveal evidence of significant climate change. The dry part of the present lake shows that the lake has been larger in the last several decades. But, as NASA scientists point out, the lake was once many times larger than its present surface area, as shown by numerous sweeping curves of ancient beaches which are now situated many kilometers from the present shoreline, at higher altitudes (upper right). Inland lakes are highly sensitive to the exact equilibrium between the amount of inflow from contributing rivers like Wadi Batha and evaporation. Each beach ridge therefore shows a different lake level and thus a different balance in the lake-river-climate system. A smaller river enters from the south (top right) and cuts through the beach reaches on its way to the lake. The irregular, elongated, tan patches to the west of the lake are linear dunes aligned parallel to the dominant winds which blow from the northeast. The dunes have all formed on the downwind side (southwest) side of the lake since the lake bed and delta provide the sands which have built the dunes. The dunes indicate that during past climatic phases the lake has been almost or completely dry on repeated occasions—often enough for these great dunes, many kilometers long and several meters high, to form even in the lowest parts of the lake. The islands visible in the center of the lake are likewise remnants of dunes. These dunes are smaller than those on the lake margin, presumably because waves from the lake have eroded them. Villages occupy the points of some major dunes, and some islands, where fishermen can gain easy access to the lake.

Recent seasonal variations in arid landscape cover and aeolian sand mobility, Navajo Nation, southwestern U.S.

USGS Publications Warehouse

Draut, Amy E.; Redsteer, Margaret Hiza; Amoroso, Lee; Giosan, Liviu; Fuller, Dorian Q.; Nicoll, Kathleen; Flad, Rowan K.; Clift, Peter D.

2013-01-01

The socioeconomic impacts of climate change pose problems not only in devel- oping countries but also to residents of arid lands in the United States among marginalized societies with limited economic means. In the Navajo Nation, warming temperatures and recent drought have increased aeolian sediment mobility such that large, migrating sand dunes affect grazing lands, housing, and road access. Dust derived from this region also affects albedo and longevity of the Rocky Mountains snowpack, located downwind. We present initial results from a study that monitors sand transport and vegetation within a 0.2 km2 site in the Navajo lands, measuring the effects of drought on landscape stability since 2009. Sand mobility decreased substantially as 1 year with near-normal monsoon rainfall (2010) somewhat abated a decade-long drought, temporarily doubling vegetation cover. Vegetation that grew during 2010, with adequate rain, died off rapidly during dry conditions in 2011. Short-term increases in rainfall that promote annual, but not perennial, plant growth will not improve landscape stability in the long term. Climate projections suggest that a warmer, drier climate and potentially enhanced sediment supply from ephem- eral washes will further increase aeolian sand transport and dune activity, worsening the present challenges to people living in this region. Connections among climate, vegetation, and aeolian sediment erodibility in this region are highly relevant to other areas of the world with similar environmental problems.

Effects of reconstruction of a pre-European vertebrate assemblage on ground-dwelling arachnids in arid Australia.

PubMed

Silvey, Colin J; Hayward, Matthew W; Gibb, Heloise

2015-06-01

Species loss can result in changes in assemblage structure and ecosystem function through ecological cascades. Australian vertebrate assemblages changed significantly following European colonisation, which resulted in the establishment of invasive vertebrates and the loss of native marsupials, many of which consume invertebrates. Conservation focusses on the removal of invasive carnivores and the reintroduction of regionally extinct species to fenced sites, resulting in what could be considered a reconstruction of pre-European vertebrate assemblages. In semi-arid Australian spinifex mallee ecosystems, we asked: (1) what is the effect of reconstructed pre-European vertebrate assemblages on native arachnid assemblages? and (2) what direct or indirect mechanisms (predation, disturbance and/or competition) could plausibly be responsible for these effects? We compared sites with reconstructed vertebrate assemblages with paired control sites. Arachnids were sampled using pitfall trapping and direct searching. Hypotheses regarding mechanisms were tested using scat analysis (predation) and by comparing burrow depth (disturbance) and scorpion mass (competition) between control and reconstructed sites. The dominant dune scorpion, Urodacus yaschenkoi, was less abundant and a wolf spider (Lycosa gibsoni species group) more abundant in reconstructed sites. Differences in spider assemblage composition were marginally non-significant. Scat analysis confirmed native vertebrate predation on scorpions and we found no evidence that competition or disturbance affected scorpions. We, thus, suggest that changes in spider assemblages may have resulted from ecological cascades via decreases in dune scorpions. The loss of omnivorous mammals and other changes associated with the invasion of carnivores may, therefore, have had broad-reaching consequences for native arachnid assemblages in Australian ecosystems.

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

NASA Technical Reports Server (NTRS)

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

1974-01-01

The author has identified the following significant results. It is possible to determine, from ERTS imagery, native arid plant distribution. Using techniques of multispectral masking and extensive fieldwork, three native vegetation communities were defined and mapped in the Avra Valley study area. A map was made of the Yuma area with the aid of ground truth correlations between areas of desert pavement visible on ERTS images and unique vegetation types. With the exception of the Yuma soil-vegetation correlation phenomena, only very gross differentiations of desert vegetation communities can be made from ERTS data. Vegetation communities with obvious vegetation density differences such as saguaro-paloverde, creosote bush, and riparian vegetation can be separated on the Avra Valley imagery while more similar communities such as creosote bush and saltbush could not be differentiated. It is suggested that large differences in vegetation density are needed before the signatures of two different vegetation types can be differentiated on ERTS imagery. This is due to the relatively insignificant contribution of vegetation to the total radiometric signature of a given desert scene. Where more detailed information concerning the vegetation of arid regions is required, large scale imagery is appropriate.

The spectral changes of deforestation in the Brazilian tropical savanna.

PubMed

Trancoso, Ralph; Sano, Edson E; Meneses, Paulo R

2015-01-01

The Cerrado is a biome in Brazil that is experiencing the most rapid loss in natural vegetation. The objective of this study was to analyze the changes in the spectral response in the red, near infrared (NIR), middle infrared (MIR), and normalized difference vegetation index (NDVI) when native vegetation in the Cerrado is deforested. The test sites were regions of the Cerrado located in the states of Bahia, Minas Gerais, and Mato Grosso. For each region, a pair of Landsat Thematic Mapper (TM) scenes from 2008 (before deforestation) and 2009 (after deforestation) was compared. A set of 1,380 samples of deforested polygons and an equal number of samples of native vegetation have their spectral properties statistically analyzed. The accuracy of deforestation detections was also evaluated using high spatial resolution imagery. Results showed that the spectral data of deforested areas and their corresponding native vegetation were statistically different. The red band showed the highest difference between the reflectance data from deforested areas and native vegetation, while the NIR band showed the lowest difference. A consistent pattern of spectral change when native vegetation in the Cerrado is deforested was identified regardless of the location in the biome. The overall accuracy of deforestation detections was 97.75%. Considering both the marked pattern of spectral changes and the high deforestation detection accuracy, this study suggests that deforestation in Cerrado can be accurately monitored, but a strong seasonal and spatial variability of spectral changes might be expected.

Quantifying energy and water fluxes in dry dune ecosystems of the Netherlands

NASA Astrophysics Data System (ADS)

Voortman, B. R.; Bartholomeus, R. P.; van der Zee, S. E. A. T. M.; Bierkens, M. F. P.; Witte, J. P. M.

2015-04-01

Coastal and inland dunes provide various ecosystem services that are related to groundwater, such as drinking water production and biodiversity. To manage groundwater in a sustainable manner, knowledge of actual evapotranspiration (ETa) for the various land covers in dunes is essential. Aiming at improving the parameterization of dune vegetation in hydro-meteorological models, this study explores the magnitude of energy and water fluxes in an inland dune ecosystem in the Netherlands. Hydro-meteorological measurements were used to parameterize the Penman-Monteith evapotranspiration model for four different surfaces: bare sand, moss, grass and heather. We found that the net longwave radiation (Rnl) was the largest energy flux for most surfaces during daytime. However, modelling this flux by a calibrated FAO-56 Rnl model for each surface and for hourly time steps was unsuccessful. Our Rnl model, with a novel sub-model using solar elevation angle and air temperature to describe the diurnal pattern in radiative surface temperature, improved Rnl simulations considerably. Model simulations of evaporation from moss surfaces showed that the modulating effect of mosses on the water balance is species dependent. We demonstrate that dense moss carpets (Campylopus introflexus) evaporate more (5%, +14 mm) than bare sand (total of 258 mm in 2013), while more open structured mosses (Hypnum cupressiforme) evaporate less (-30%, -76 mm) than bare sand. Additionally, we found that a drought event in the summer of 2013 showed a pronounced delayed signal on lysimeter measurements of ETa for the grass and heather surfaces respectively. Due to the desiccation of leaves after the drought event, and their feedback on the parameters of the Penman-Monteith equation, the potential evapotranspiration in the year 2013 dropped with 9% (-37mm) and 10% (-61 mm) for the grass and heather surfaces respectively, which subsequently led to lowered ETa of 8% (-29 mm) and 7% (-29 mm). These feedbacks are of importance to water resources, especially during a changing climate with increasing number of drought days. Therefore, such feedbacks need to be integrated into a coupled plant physiological and hydro-meteorological model to accurately simulate ETa. In addition, our study showed that groundwater recharge in dunes can be increased considerably by promoting moss vegetation, especially of open structured moss species.

Impacts of deer herbivory on vegetation in Rock Creek Park, 2001-2009

USGS Publications Warehouse

Kraft, Cairn C.; Hatfield, Jeff S.

2011-01-01

Starting in 2001, vegetation data have been collected annually in 16 study modules consisting of paired (1x4 m) fenced plots and unfenced control plots located in the upland forests of Rock Creek Park, Washington, D.C. Vegetation data collected from 2001-2009 have been analyzed to determine impacts of deer herbivory on vegetation in the park. Differences between fenced plots and unfenced control plots were analyzed for the following variables: cover provided by various groups of species (woody, herbaceous, native, non-native, trees, shrubs, and woody vines), as well as by individual dominant species, vegetation thickness (a measure of percent cover projected horizontally that provides information on the vertical distribution of vegetation), and species richness overall and for groups of species (woody, herbaceous, native, non-native, trees, shrubs, and woody vines). The analyses were performed using repeated measures analysis of variance (ANOVA) and associated tests. Vegetation in plots protected from deer herbivory for 9 years showed significantly greater vegetative cover compared to plots not protected from deer herbivory. This effect was most pronounced for woody and shrub cover. Cover by the dominant species was not significantly greater in the fenced plots compared to the unfenced control plots, indicating that the significant differences observed for groups were not driven by single species within those groups. With respect to vegetation thickness, results indicate that protection from deer herbivory produced significantly higher levels of vegetation in the fenced plots compared to the unfenced control plots for both the Low (0-30 cm) and Middle (30-110 cm) height classes. Protection from deer herbivory has led to higher overall species richness and higher species richness for woody species, natives, and shrubs compared to plots not receiving protection. There is also evidence that plots protected from deer herbivory and those not receiving this protection are diverging over time with respect to a number of variables such as cover by woody and shrub species, cover in the lowest height class, and species richness of woody and native species. Recommendations were made regarding future sampling.

A review of the chronologies and geomorphology of the aeolian landforms in the northwestern Negev dunefield (Israel)

NASA Astrophysics Data System (ADS)

Roskin, Joel

2015-04-01

The northwestern (NW) Negev Desert dunefield covering an area of only 1,300 km2, comprises the eastern end of the northern Sinai Peninsula - NW Negev erg and is probably the most densely dated dune body in the INQUA Dunes Atlas chronologic database. Over 230 luminescence ages (TL, IRSL, and mainly OSL) and radiocarbon dates have been retrieved over the past course of 20 years from calcic and sandy palaeosols serving as dune substrates, sand sheets, vegetated linear dunes (VLDs), fluvial deposits, and archaeological sites. Despite being from different deposit types and aeolian morphologies, and based on different methodologies, the chronologies usually show good compatibility. By reviewing and reassessing the significance of the Eastern Mediterranean INQUA Dunes Atlas chronologies, along with detailed stratigraphic, structural and geomorphologic data and understandings, the major, and possibly extreme, episodes of aeolian activity and stability are outlined. Repetitive chronostratigraphic sequences in VLDs indicate that this dune type, at least in the Negev, comprises a reliable recorder of main dune mobilization periods. This presentation demonstrates that certain combinations of research finds, using different OSL dating strategies and other regional and local late Quaternary records and in particular aeolian ones, are required assets for providing for acceptable local and regional palaeoclimatic interpretations. The distribution of the VLD chronologies points to rapid mobilization during the Heinrich 1 and Younger Dryas, characterized by powerful winds, though VLDs also form in late Holocene palaeoenvironments. Time slices illustrate the different sensitivities of the studied aeolian landforms to the source, availability, and supply of sediment; long- and short-term climate change, local human-induced environmental changes and also their joint effects, that enable evaluation of aeolian responses to future environmental and climate changes.

Long-Term Effects of Xerophytic Shrub Haloxylon ammodendron Plantations on Soil Properties and Vegetation Dynamics in Northwest China

PubMed Central

Fan, Baoli; Zhang, Aiping; Yang, Yi; Ma, Quanlin; Li, Xuemin; Zhao, Changming

2016-01-01

The xerophytic desert shrub Haloxylon ammodendron (C. A. Mey.) Bunge. is distributed naturally in Asian and African deserts, and is widely used for vegetation restoration in the desert regions of Northern China. However, there are limited long-term chrono-sequence studies on the impact of changed soil properties and vegetation dynamics following establishment of this shrub on mobile sand dunes. In Minqin County, Gansu Province, we investigated soil properties and herbaceous vegetation development of 10, 20, 30, 40, 50-year-old H. ammodendron plantations on mobile sand dunes. Soil sampling at two depths (0–5 and 5–20 cm) under the shrubs determined SOC, nutrition and soil physical characteristics. The results showed that: establishment of H. ammodendron had improved soil physio-chemical properties, increased thickness of soil crusts and coverage of biological soil crusts (BSCs), and promoted development of topsoil over an extended period of 5 decades. Soil texture and soil nutrition improved along the chrono-sequence according to three distinct phases: i) an initial fast development from 0 to 10 years, ii) a stabilizing phase from 10 to 30 years followed by iii) a relatively marked restoration development in 40 and 50-year-old plantations. Meanwhile, herbaceous community coverage also markedly increased in 30-year-old plantations. However, both soil and vegetation restoration were very slow due to low annual precipitation in Minqin county compared to other Northern China sand afforestation sites. Canonical Correspondence Analysis results demonstrated that herbaceous plant development was closely associated with changes in soil texture (increased clay and silt percentage) and availability of soil nutrients. Thus our results indicated that selection of the long-lived shrub H. ammodendron is an essential and effective tool in arid desert re-vegetation. PMID:27992458

Livestock grazing supports native plants and songbirds in a California annual grassland.

PubMed

Gennet, Sasha; Spotswood, Erica; Hammond, Michele; Bartolome, James W

2017-01-01

Over eight years we measured the effects of plant community composition, vegetation structure, and livestock grazing on occurrence of three grassland bird species-Western Meadowlark (Sturnella neglecta), Horned Lark (Eremophila alpestris), and Grasshopper Sparrow (Ammodramus savannarum)-at sites in central California during breeding season. In California's Mediterranean-type climatic region, coastal and inland grassland vegetation is dominated by exotic annual grasses with occasional patches of native bunchgrass and forbs. Livestock grazing, primarily with beef cattle, is the most widely used management tool. Compared with ungrazed plots, grazed plots had higher bare ground, native plant cover, and vertically heterogeneous vegetation. Grazed plots also had less plant litter and shorter vegetation. Higher native plant cover, which is predominantly composed of bunchgrasses in our study area, was associated with livestock grazing and north-facing aspects. Using an information theoretic approach, we found that all three bird species had positive associations with native plant abundance and neutral (Western Meadowlark, Grasshopper Sparrow) or positive (Horned Lark) association with livestock grazing. All species favored flatter areas. Horned Larks and Western Meadowlark occurred more often where there were patches of bare ground. Western Meadowlarks and Grasshopper Sparrows were most common on north-facing slopes, suggesting that these species may be at risk from projected climate change. These findings demonstrate that livestock grazing is compatible with or supports grassland bird conservation in Mediterranean-type grasslands, including areas with high levels of exotic annual grass invasion, in part because grazing supports the persistence of native plants and heterogeneity in vegetation structure. However, conservation of low-lying grasslands with high native species presence, and active management to increase the abundance of native plant species are also likely to be important for sustaining grassland birds long-term.

Invasive plant architecture alters trophic interactions by changing predator abundance and behavior.

PubMed

Pearson, Dean E

2009-03-01

As primary producers, plants are known to influence higher trophic interactions by initiating food chains. However, as architects, plants may bypass consumers to directly affect predators with important but underappreciated trophic ramifications. Invasion of western North American grasslands by the perennial forb, spotted knapweed (Centaurea maculosa), has fundamentally altered the architecture of native grassland vegetation. Here, I use long-term monitoring, observational studies, and field experiments to document how changes in vegetation architecture have affected native web spider populations and predation rates. Native spiders that use vegetation as web substrates were collectively 38 times more abundant in C. maculosa-invaded grasslands than in uninvaded grasslands. This increase in spider abundance was accompanied by a large shift in web spider community structure, driven primarily by the strong response of Dictyna spiders to C. maculosa invasion. Dictyna densities were 46-74 times higher in C. maculosa-invaded than native grasslands, a pattern that persisted over 6 years of monitoring. C. maculosa also altered Dictyna web building behavior and foraging success. Dictyna webs on C. maculosa were 2.9-4.0 times larger and generated 2.0-2.3 times higher total prey captures than webs on Achillea millefolium, their primary native substrate. Dictyna webs on C. maculosa also captured 4.2 times more large prey items, which are crucial for reproduction. As a result, Dictyna were nearly twice as likely to reproduce on C. maculosa substrates compared to native substrates. The overall outcome of C. maculosa invasion and its transformative effects on vegetation architecture on Dictyna density and web building behavior were to increase Dictyna predation on invertebrate prey >/=89 fold. These results indicate that invasive plants that change the architecture of native vegetation can substantially impact native food webs via nontraditional plant --> predator --> consumer linkages.

Native vegetation establishment for IDOT erosion control best management practices.

DOT National Transportation Integrated Search

2014-05-01

The objective of this report was to develop native roadside vegetation best management practices for : the Illinois Department of Transportation. A review of current practices was undertaken, along with a : review of those of other state departments ...

Compositional Signatures in Acoustic Backscatter Over Vegetated and Unvegetated Mixed Sand-Gravel Riverbeds

NASA Astrophysics Data System (ADS)

Buscombe, D.; Grams, P. E.; Kaplinski, M. A.

2017-10-01

Multibeam acoustic backscatter has considerable utility for remote characterization of spatially heterogeneous bed sediment composition over vegetated and unvegetated riverbeds of mixed sand and gravel. However, the use of high-frequency, decimeter-resolution acoustic backscatter for sediment classification in shallow water is hampered by significant topographic contamination of the signal. In mixed sand-gravel riverbeds, changes in the abiotic composition of sediment (such as homogeneous sand to homogeneous gravel) tend to occur over larger spatial scales than is characteristic of small-scale bedform topography (ripples, dunes, and bars) or biota (such as vascular plants and periphyton). A two-stage method is proposed to filter out the morphological contributions to acoustic backscatter. First, the residual supragrain-scale topographic effects in acoustic backscatter with small instantaneous insonified areas, caused by ambiguity in the local (beam-to-beam) bed-sonar geometry, are removed. Then, coherent scales between high-resolution topography and backscatter are identified using cospectra, which are used to design a frequency domain filter that decomposes backscatter into the (unwanted) high-pass component associated with bedform topography (ripples, dunes, and sand waves) and vegetation, and the (desired) low-frequency component associated with the composition of sediment patches superimposed on the topography. This process strengthens relationships between backscatter and sediment composition. A probabilistic framework is presented for classifying vegetated and unvegetated substrates based on acoustic backscatter at decimeter resolution. This capability is demonstrated using data collected from diverse settings within a 386 km reach of a canyon river whose bed varies among sand, gravel, cobbles, boulders, and submerged vegetation.

Vegetation, substrate, and eolian sediment transport at Teesto Wash, Navajo Nation, 2009-2012

USGS Publications Warehouse

Draut, Amy E.; Redsteer, Margaret Hiza; Amoroso, Lee

2012-01-01

On the Navajo Nation, southwestern United States, warming temperatures and recent drought have increased eolian (windblown) sediment mobility such that large, migrating sand dunes affect grazing lands, housing, and road access. We present an assessment of seasonal variations in sand transport, mobility, and ground cover (vegetation and substrate) within a 0.2-km2 study area near Teesto Wash, southern Navajo Nation, as part of a multiyear study measuring the effects of drought on landscape stability. Sand mobility in the study area decreased substantially as one year (2010) with near-normal monsoon rainfall somewhat abated a decade-long drought, temporarily doubling vegetation cover. The invasive annual plant Russian thistle (Salsola sp.), in particular, thrived after the monsoon rains of 2010. Vegetation that grew during that year with adequate rain died off rapidly during drier conditions in 2011 and 2012, and the proportion of bare, open sand area increased steadily after summer 2010. We infer that isolated seasonal increases in rainfall will not improve landscape stability in the long term because sustained increase in perennial plants, which are more effective than annual plants at stabilizing sand against wind erosion, requires multiple consecutive seasons of adequate rain. On the basis of climate projections, a warmer, drier climate and potentially enhanced sediment supply from ephemeral washes may further increase eolian sediment transport and dune activity, worsening the present challenges to people living in this region. Connections between climate, vegetation cover, and eolian sediment erodibility in this region also are highly relevant for studies in other regions worldwide with similar environmental characteristics.

Compositional signatures in acoustic backscatter over vegetated and unvegetated mixed sand-gravel riverbeds

USGS Publications Warehouse

Buscombe, Daniel; Grams, Paul E.; Kaplinski, Matt A.

2017-01-01

Multibeam acoustic backscatter has considerable utility for remote characterization of spatially heterogeneous bed sediment composition over vegetated and unvegetated riverbeds of mixed sand and gravel. However, the use of high-frequency, decimeter-resolution acoustic backscatter for sediment classification in shallow water is hampered by significant topographic contamination of the signal. In mixed sand-gravel riverbeds, changes in the abiotic composition of sediment (such as homogeneous sand to homogeneous gravel) tend to occur over larger spatial scales than is characteristic of small-scale bedform topography (ripples, dunes, and bars) or biota (such as vascular plants and periphyton). A two-stage method is proposed to filter out the morphological contributions to acoustic backscatter. First, the residual supragrain-scale topographic effects in acoustic backscatter with small instantaneous insonified areas, caused by ambiguity in the local (beam-to-beam) bed-sonar geometry, are removed. Then, coherent scales between high-resolution topography and backscatter are identified using cospectra, which are used to design a frequency domain filter that decomposes backscatter into the (unwanted) high-pass component associated with bedform topography (ripples, dunes, and sand waves) and vegetation, and the (desired) low-frequency component associated with the composition of sediment patches superimposed on the topography. This process strengthens relationships between backscatter and sediment composition. A probabilistic framework is presented for classifying vegetated and unvegetated substrates based on acoustic backscatter at decimeter resolution. This capability is demonstrated using data collected from diverse settings within a 386 km reach of a canyon river whose bed varies among sand, gravel, cobbles, boulders, and submerged vegetation.

Impacts of erosion control treatments on native vegetation recovery after severe wildfire in the Eastern Cascades, USA

Treesearch

Erich Kyle Dodson; David W. Peterson; Richy J. Harrod

2010-01-01

Slope stabilization treatments like mulching and seeding are used to increase soil cover and reduce runoff and erosion following severe wildfires, but may also retard native vegetation recovery. We evaluated the effects of seeding and fertilization on the cover and richness of native and exotic plants and on individual plant species following the 2004 Pot Peak wildfire...

A preliminary study of effects of feral pig density on native Hawaiian montane rainforest vegetation

USGS Publications Warehouse

Scheffler, Pamela Y.; Pratt, Linda; Foote, David; Magnacca, Karl

2012-01-01

This study aimed to examine the effects of different levels of pig density on native Hawaiian forest vegetation. Pig sign was measured across four pig management units in the 'Öla'a Forest from 1998 through 2004 and pig density estimated based upon pig activity. Six paired vegetation monitoring plots were established in the units, each pair straddling a pig fence. Percent cover and species richness of understory vegetation, ground cover, alien species, and preferred pig forage plants were measured in 1997 and 2003 and compared with pig density estimates. Rainfall and hunting effort and success by management personnel were also tracked over the study period. Vegetation monitoring found a higher percentage of native plants in pig-free or low-pig areas compared to those with medium or high pig densities, with no significant change in the percent native plant species between the first and second monitoring periods. Differences between plots were strongly affected by location, with a higher percentage of native plants in western plots, where pig damage has historically been lower. Expansion of this survey with more plots would help improve the statistical power to detect differences in vegetation caused by pigs. Because of the limited vegetation sampling in this study, the results must be viewed as descriptive. We compare the vegetation within 30 x 30 m plots across three thresholds of historical pig density and show how pig densities can change in unanticipated directions within management units. While these results cannot be extrapolated to area-wide effects of pig activity, these data do contribute to a growing body of information on the impacts of feral pigs on Hawaiian plant communities.

Changes in plant species composition of coastal dune habitats over a 20-year period

PubMed Central

Del Vecchio, Silvia; Prisco, Irene; Acosta, Alicia T. R.; Stanisci, Angela

2015-01-01

Coastal sandy ecosystems are increasingly being threatened by human pressure, causing loss of biodiversity, habitat degradation and landscape modifications. However, there are still very few detailed studies focussing on compositional changes in coastal dune plant communities over time. In this work, we investigated how coastal dune European Union (EU) habitats (from pioneer annual beach communities to Mediterranean scrubs on the landward fixed dunes) have changed during the last 20 years. Using phytosociological relevés conducted in 1989–90 and in 2010–12, we investigated changes in floristic composition over time. We then compared plant cover and the proportion of ruderal, alien and habitat diagnostic species (‘focal species’) in the two periods. Finally, we used Ellenberg indicator values to define the ‘preferences’ of the plant species for temperature and moisture. We found that only fore dune habitats showed significant differences in species cover between the two time periods, with higher plant cover in the more recent relevés and a significant increase in thermophilic species. Although previous studies have demonstrated consistent habitat loss in this area, we observed that all coastal dune plant communities remain well represented, after a 20-year period. However, fore dunes have been experiencing significant compositional changes. Although we cannot confirm whether the observed changes are strictly related to climatic changes, to human pressure or to both, we hypothesize that a moderate increment in average yearly temperature may have promoted the increase in plant cover and the spread of thermophilic species. Thus, even though human activities are major driving forces of change in coastal dune vegetation, at the community scale climatic factors may also play important roles. Our study draws on re-visitation studies which appear to constitute a powerful tool for the assessment of the conservation status of EU habitats. PMID:25750408

High-Resolution Monitoring of Coastal Dune Erosion and Growth Using an Unmanned Aerial Vehicle

NASA Astrophysics Data System (ADS)

Ruessink, G.; Markies, H.; Van Maarseveen, M.

2014-12-01

Coastal foredunes lose and gain sand through marine and aeolian processes, but coastal-evolution models that can accurately predict both wave-driven dune erosion and wind-blown dune growth are non-existing. This is, together with a limited understanding of coastal aeolian process dynamics, due to the lack of adequate field data sets from which erosion and supply volumes can be studied simultaneously. Here, we quantify coastal foredune dynamics using nine topographic surveys performed near Egmond aan Zee, The Netherlands, between September 2011 and March 2014 using an unmanned aerial vehicle (UAV). The approximately 0.75-km long study site comprises a 30-100 m wide sandy beach and a 20-25 m high foredune, of which the higher parts are densely vegetated with European marram grass. Using a structure-from-motion workflow, the 200-500 photographs taken during each UAV flight were processed into a point cloud, from which a geo-referenced digital surface model with a 0.25 x 0.25 m resolution was subsequently computed. Our data set contains two dune-erosion events, including that due to storm Xaver (December 2013), which caused one of the highest surge levels in the southern North Sea region for the last decades. Dune erosion during both events varied alongshore from the destruction of embryonic dunes on the upper beach to the slumping of the entire dune face. During the first storm (January 2012), erosion volumes ranged from 5 m3/m in the (former) embryonic dune field to over 40 m3/m elsewhere. During the subsequent 11 (spring - autumn) months, the foredune accreted by (on average) 8 m3/m, again with substantial alongshore variability (0 - 20 m3/m). Intriguingly, volume changes during the 2012-2013 winter were minimal. We will compare the observed aeolian supply rates with model predictions and discuss reasons for their temporal variability. Funded by the Dutch Organisation for Scientific Research NWO.

Eolian sand transport pathways in the southwestern United States: Importance of the Colorado River and local sources

USGS Publications Warehouse

Muhs, D.R.; Reynolds, R.L.; Been, J.; Skipp, G.

2003-01-01

Geomorphologists have long recognized that eolian sand transport pathways extend over long distances in desert regions. Along such pathways, sediment transport by wind can surmount topographic obstacles and cross major drainages. Recent studies have suggested that three distinct eolian sand transport pathways exist (or once existed) in the Mojave and Sonoran Desert regions of the southwestern United States. One hypothesized pathway is colian sand transport from the eastern Mojave Desert of California into western Arizona, near Parker, and would require sand movement across what must have been at least a seasonally dry Colorado River valley. We tested this hypothesis by mineralogical, geochemical and magnetic analyses of eolian sands on both sides of the Colorado River, as well as sediment from the river itself. Results indicate that dunes on opposite sides of the Colorado River are mineralogically distinct: eastern California dunes are feldspar-rich whereas western Arizona dunes are quartz-rich, derived from quartz-rich Colorado River sediments. Because of historic vegetation changes, little new sediment from the Colorado River is presently available to supply the Parker dunes. Based on this study and previous work, the Colorado River is now known to be the source of sand for at least three of the major dune fields of the Sonoran Desert of western Arizona and northern Mexico. On the other hand, locally derived alluvium appears to be a more important source of dune fields in the Mojave Desert of California. Although many geomorphologists have stressed the importance of large fluvial systems in the origin of desert dune fields, few empirical data actually exist to support this theory. The results presented here demonstrate that a major river system in the southwestern United States is a barrier to the migration of some dune fields, but essential to the origin of others. Published by Elsevier Science Ltd.

Sand-grain micromorphology used as a sediment-source indicator for Kharga Depression dunes (Western Desert, S Egypt)

NASA Astrophysics Data System (ADS)

Woronko, B.; Dłużewski, M.; Woronko, D.

2017-12-01

Roundness and surface-feature characteristics of sand grains collected from two dune ridges in Kharga Depression (southern Egypt) were tested for potential use as source-to-sink indicators of dunes movement. Grain examination was accommodated through Scanning Electron Microscope (SEM) analysis. Five grain types were distinguished: A) fresh; B) sheet precipitated with ;raindrop; structures; C) platy precipitated; D) broken; and E) with chemically etched surfaces-each type diagnostic of a specific geomorphic inheritance. Regarding the level of sphericity, these grains were subdivided into nine roundness classes (0.1-0.9), where angular grains are marked by 0.1 and very well-rounded grains by 0.9. Significant roundness and grain-type surface variations are observed both along dune ridges and between them. Poorly and medium-rounded grain populations dominate, along with sheet-precipitated grains. The contribution of well- and very well-rounded grains is low. The northern part of both eastern and western dune ridges is characterized by grains that represent high-energy aqueous environments with well-rounded grains, whereas platy precipitated grains with a lower level of roundness are concentrated in the middle part of the dune ridges. The southern part of the Kharga Depression is again characterized by sheet-precipitated grains. Our results indicate that the northern part of dune ridges in the Kharga Depression is mainly built of sands that originate from beyond the depression (e.g., Ghard Abu-Maharik) and the weathered deposits of the Nubian and Moghra Sandstones. The dunes in central and southern part of the Kharga Depression also derive sand from a local depression bottom comprised of playa and fluvial deposits. The growing importance of the local sand source may be explained by the lowering of the local groundwater table, which resulted in playa drying. This groundwater loss resulted in the degradation of the vegetation cover, facilitating an increase in wind entrainment of playa sediments.

Xylocopa bees in tropical coastal sand dunes: use of resources and their floral syndromes.

PubMed

Figueiredo, N; Gimenes, M; de Miranda, M D; Oliveira-Rebouças, P

2013-06-01

Large bees such as species from Xylocopa Latreille are usually associated with pollination in tropical sand dune areas, which frequently present shrubby herbaceous vegetation adapted to conditions of high salinity, high solar radiation and strong winds. We report on the diversity of Xylocopa and the plants they visited to collect nectar and pollen, focusing on the floral syndromes they present in these plants and on the breadth of the trophic niche in a tropical sand dune fragment over the year. The field work was carried out monthly in Baixio (Bahia, Brazil; Northern Coast Environmental Protection Area) from April 2008 to March 2009, over two consecutive days, from 06:30 AM to 05:00 PM. The medium-large body sized Xylocopa (Neoxylocopa) cearensis Ducke and Xylocopa (Schonnherria) subcyanea Pérez were noticeable for their frequency, constancy on the flowers and sharing of plant species. Xylocopa spp. visited plants with flowers of different shapes, colors, inflorescence arrangement and syndromes. However, their resource collections were mainly concentrated on Cuphea brachiata, Waltheria cinerascens, Croton sellowii and Chamaecrista ramosa, which may be considered key species for Xylocopa spp. maintenance in coastal sand dune and restinga environments in Northeast Brazil.

Modeling invasive alien plant species in river systems: Interaction with native ecosystem engineers and effects on hydro-morphodynamic processes

NASA Astrophysics Data System (ADS)

van Oorschot, M.; Kleinhans, M. G.; Geerling, G. W.; Egger, G.; Leuven, R. S. E. W.; Middelkoop, H.

2017-08-01

Invasive alien plant species negatively impact native plant communities by out-competing species or changing abiotic and biotic conditions in their introduced range. River systems are especially vulnerable to biological invasions, because waterways can function as invasion corridors. Understanding interactions of invasive and native species and their combined effects on river dynamics is essential for developing cost-effective management strategies. However, numerical models for simulating long-term effects of these processes are lacking. This paper investigates how an invasive alien plant species affects native riparian vegetation and hydro-morphodynamics. A morphodynamic model has been coupled to a dynamic vegetation model that predicts establishment, growth and mortality of riparian trees. We introduced an invasive alien species with life-history traits based on Japanese Knotweed (Fallopia japonica), and investigated effects of low- and high propagule pressure on invasion speed, native vegetation and hydro-morphodynamic processes. Results show that high propagule pressure leads to a decline in native species cover due to competition and the creation of unfavorable native colonization sites. With low propagule pressure the invader facilitates native seedling survival by creating favorable hydro-morphodynamic conditions at colonization sites. With high invader abundance, water levels are raised and sediment transport is reduced during the growing season. In winter, when the above-ground invader biomass is gone, results are reversed and the floodplain is more prone to erosion. Invasion effects thus depend on seasonal above- and below ground dynamic vegetation properties and persistence of the invader, on the characteristics of native species it replaces, and the combined interactions with hydro-morphodynamics.

Dust from southern Africa: rate of emission and biogeochemical properties

USDA-ARS?s Scientific Manuscript database

The stabilized linear dunefields in the southern Kalahari show signs of reactivation due to reduced vegetation cover owing to drought and/or overgrazing. It has been demonstrated with a laboratory dust generator that the southern Kalahari soils are good emitters of dust and that large-scale dune rea...

Role of invasive Melilotus officinalis in two native plant communities

USGS Publications Warehouse

Van Riper, Laura C.; Larson, Diane L.

2009-01-01

This study examines the impact of the exotic nitrogen-fixing legume Melilotus officinalis (L.) Lam. on native and exotic species cover in two Great Plains ecosystems in Badlands National Park, South Dakota. Melilotus is still widely planted and its effects on native ecosystems are not well studied. Melilotus could have direct effects on native plants, such as through competition or facilitation. Alternatively, Melilotus may have indirect effects on natives, e.g., by favoring exotic species which in turn have a negative effect on native species. This study examined these interactions across a 4-year period in two contrasting vegetation types: Badlands sparse vegetation and western wheatgrass (Pascopyrum smithii) mixed-grass prairie. Structural equation models were used to analyze the pathways through which Melilotus, native species, and other exotic species interact over a series of 2-year time steps. Melilotus can affect native and exotic species both in the current year and in the years after its death (a lag effect). A lag effect is possible because the death of a Melilotus plant can leave an open, potentially nitrogen-enriched site on the landscape. The results showed that the relationship between Melilotus and native and exotic species varied depending on the habitat and the year. In Badlands sparse vegetation, there was a consistent, strong, and positive relationship between Melilotus cover and native and exotic species cover suggesting that Melilotus is acting as a nurse plant and facilitating the growth of other species. In contrast, in western wheatgrass prairie, Melilotus was acting as a weak competitor and had no consistent effect on other species. In both habitats, there was little evidence for a direct lag effect of Melilotus on other species. Together, these results suggest both facilitative and competitive roles for Melilotus, depending on the vegetation type it invades.

The role of sexual vs. asexual recruitment of Artemisia wudanica in transition zone habitats between inter-dune lowlands and active dunes in Inner Mongolia, China

NASA Astrophysics Data System (ADS)

Wang, Yongcui; Alberto, Busso Carlos; Jiang, Deming; Ala, Musa; Li, Xuehua; Zhou, Quanlai; Lin, Jixiang; Ren, Guohua; Jia, Lian

2016-04-01

Artemisia wudanica is an endemic, perennial, pioneering psammophyte species in the sand dune ecosystems of western Horqin Sand Land in northern China. However, no studies have addressed how sexual and asexual reproduction modes of A. wudanica perform at the transitional zones between active dune inter-dune lowlands and active dunes. In early spring, quadrats were randomly set up in the study area to monitor surviving seedling and/or ramet density and frequency coming from sexual/asexual reproduction of A. wudanica. Iron sticks were inserted near each quadrat to determine wind erosion intensity (WE). Additionally, soil samples were collected nearby each quadrat to test for soil moisture (SM), organic matter (OM) and pH. Surviving seedlings of A. wudanica showed an inverse response in comparison with ramets to SM, OM and WE. Soil moisture showed the most positive effect, and WE the negative effect, on surviving, sexual reproduction seedlings. Contrarily, WE had the most positive effect, and SM the negative effect, on asexual reproduction ramets. This suggests that increases in SM and decreases in WE should benefit recruitment of A. wudanica seedlings. On the contrary, ramets coming from asexual reproduction showed a different response to environmental factors in transition zone habitats. While SM was not a key constraint for the survival of seedlings, they showed a better, positive response to wind erosion environments. Overall, various study environmental parameters could be improved to foster A. wudanica invasion and settlement in the plant community through different reproductive modes, thereby promoting vegetation restoration and rehabilitation.

Differences in Fruit and Vegetable Intake by Race/Ethnicity and by Hispanic Origin and Nativity Among Women in the Special Supplemental Nutrition Program for Women, Infants, and Children, 2015.

PubMed

Di Noia, Jennifer; Monica, Dorothy; Cullen, Karen Weber; Pérez-Escamilla, Rafael; Gray, Heewon Lee; Sikorskii, Alla

2016-08-25

The objective of this exploratory study was to determine whether fruit and vegetable consumption differed by race/ethnicity, by origin and nativity among Hispanics, and by language preference (as an indicator of acculturation) among foreign-born Hispanics. We recruited 723 women enrolled in the Special Supplemental Nutrition Program for Women, Infants and Children (WIC) and orally administered a questionnaire containing demographic items, validated measures of food security status and social desirability trait, and the Behavioral Risk Factor Surveillance System fruit and vegetable module. Differences in intakes of 100% fruit juice, fruit, cooked or canned beans, and dark green, orange-colored, and other vegetables were assessed by using analysis of covariance with Bonferroni post hoc tests. Analyses were controlled for age, pregnancy status, breastfeeding status, food security status, educational attainment, and social desirability trait. The frequency of vegetable intake differed by race/ethnicity (cooked or canned beans were consumed more often among Hispanic than non-Hispanic black and non-Hispanic white or other participants, orange-colored vegetables were consumed more often among Hispanics than non-Hispanic black participants, and other vegetables were consumed more often among non-Hispanic white or other than among non-Hispanic black and Hispanic participants), origin (other vegetables were consumed more often among Columbian and other Hispanics than Dominican participants) and nativity (orange-colored vegetables were consumed more often among foreign-born than US-born Hispanics). Fruit and vegetable intake did not differ by language preference among foreign-born Hispanics. Differences in fruit and vegetable consumption among WIC participants by race/ethnicity and by Hispanic origin and nativity may have implications for WIC nutrition policies and nutrition education efforts.

Differences in Fruit and Vegetable Intake by Race/Ethnicity and by Hispanic Origin and Nativity Among Women in the Special Supplemental Nutrition Program for Women, Infants, and Children, 2015

PubMed Central

Monica, Dorothy; Cullen, Karen Weber; Pérez-Escamilla, Rafael; Gray, Heewon Lee; Sikorskii, Alla

2016-01-01

Introduction The objective of this exploratory study was to determine whether fruit and vegetable consumption differed by race/ethnicity, by origin and nativity among Hispanics, and by language preference (as an indicator of acculturation) among foreign-born Hispanics. Methods We recruited 723 women enrolled in the Special Supplemental Nutrition Program for Women, Infants and Children (WIC) and orally administered a questionnaire containing demographic items, validated measures of food security status and social desirability trait, and the Behavioral Risk Factor Surveillance System fruit and vegetable module. Differences in intakes of 100% fruit juice, fruit, cooked or canned beans, and dark green, orange-colored, and other vegetables were assessed by using analysis of covariance with Bonferroni post hoc tests. Analyses were controlled for age, pregnancy status, breastfeeding status, food security status, educational attainment, and social desirability trait. Results The frequency of vegetable intake differed by race/ethnicity (cooked or canned beans were consumed more often among Hispanic than non-Hispanic black and non-Hispanic white or other participants, orange-colored vegetables were consumed more often among Hispanics than non-Hispanic black participants, and other vegetables were consumed more often among non-Hispanic white or other than among non-Hispanic black and Hispanic participants), origin (other vegetables were consumed more often among Columbian and other Hispanics than Dominican participants) and nativity (orange-colored vegetables were consumed more often among foreign-born than US-born Hispanics). Fruit and vegetable intake did not differ by language preference among foreign-born Hispanics. Conclusion Differences in fruit and vegetable consumption among WIC participants by race/ethnicity and by Hispanic origin and nativity may have implications for WIC nutrition policies and nutrition education efforts. PMID:27560723

Assessing vulnerability to invasion by nonnative plant species at multiple spatial scales

USGS Publications Warehouse

Stohlgren, T.J.; Chong, G.W.; Schell, L.D.; Rimar, K.A.; Otsuki, Yuka; Lee, M.; Kalkhan, M.A.; Villa, C.A.

2002-01-01

Basic information on where nonnative plant species have successfully invaded is lacking. We assessed the vulnerability of 22 vegetation types (25 sets of four plots in nine study areas) to nonnative plant invasions in the north–central United States. In general, habitats with high native species richness were more heavily invaded than species-poor habitats, low-elevation areas were more invaded than high-elevation areas, and riparian zones were more invaded than nearby upland sites. For the 100 1000-m2 plots (across all vegetation types), 50% of the variation in nonnative species richness was explained by longitude, latitude, native plant species richness, soil total percentage nitrogen, and mean maximum July temperature (n = 100 plots; P < 0.001). At the vegetation-type scale (n = 25 sets of four 1000-m2 plots/type), 64% of the variation in nonnative species richness was explained by native plant species richness, elevation, and October to June precipitation (P < 0.001). The foliar cover of nonnative species (log) was strongly positively correlated with the nonnative species richness at the plot scale (r = 0.77, P < 0.001) and vegetation-type scale (r = 0.83, P < 0.001). We concluded that, at the vegetation-type and regional scales in the north–central United States, (1) vegetation types rich in native species are often highly vulnerable to invasion by nonnative plant species; (2) where several nonnative species become established, nonnative species cover can substantially increase; (3) the attributes that maintain high native plant species richness (high light, water, nitrogen, and temperatures) also help maintain nonnative plant species richness; and (4) more care must be taken to preserve native species diversity in highly vulnerable habitats.

Potential impacts of sea level rise on native plant communities and associated cultural sites in coastal areas of the main Hawaiian Islands

USGS Publications Warehouse

Jacobi, James D.; Warshauer, Frederick R.

2017-01-01

Hawaiian coastal vegetation is comprised of plant species that are adapted to growing in extremely harsh conditions (salt spray, wave wash, wind, and substrates with limited nutrients) found in this habitat zone. Prior to human colonization of Hawai‘i coastal vegetation extended as a continuous ring around each of the islands, broken only by stretches of recent lava flows or unstable cliff faces. However, since humans arrived in Hawai‘i many areas that originally supported native coastal plant communities have been highly altered or the native vegetation totally removed for agriculture, housing, or resort development, destroyed by fire, displaced by invasive plants, eaten by introduced mammals, or damaged by recreational use. This study was focused on identifying sites that still retain relatively intact and highly diverse native coastal plant communities throughout the main Hawaiian Islands that may be further impacted by projected sea level rise. Approximately 40 percent of Hawai‘i’s coastlines were found to still contain high quality native coastal plant communities. Most of these sites were located in areas where the coastal vegetation can still migrate inshore in response to rising sea level and associated inundation by waves. However, six sites with high-quality native coastal vegetation were found on low-lying offshore islets that will be totally inundated with a one meter increase in sea level and thirty sites were found to have some type of fixed barrier, such as a paved road or structure, which would restrict the plants from colonizing the adjacent inland areas. Many of these sites also have other cultural resources that are fixed in place and will definitely be impacted by rising sea level. The results of this study can help refine our understanding of Hawai‘i’s remaining native coastal vegetation and aid with the development of management and restoration strategies to ensure the long-term survival of these unique plant communities.

Last Glacial Maximum Development of Parna Dunes in Panhandle Oklahoma, USA

NASA Astrophysics Data System (ADS)

Johnson, W. C.; Halfen, A. F.; McGowen, S.; Carter, B.; Fine, S.; Bement, L. C.; Simms, A. R.

2012-12-01

Though dunefields are a ubiquitous feature of the North American Great Plains, those studied to date have consisted primarily of sand grains. In Beaver County of the Oklahoma panhandle, however, upland dune forms consist of sand-sized aggregates of silt and clay. These aptly named parna dunes occur in two swarms, range in height from 10-15 m, and have asymmetrical dome morphologies with approximate north-south dune orientations. Despite their morphological similarities to sand dunes of the region, their origin and evolution is unknown. Documenting parna dune formation in the Oklahoma panhandle will help improve our understanding of prehistoric landscape instability and climate change, particularly in the central Great Plains where such records are limited. Panhandle parna dunes are typified by Blue Mound, our best documented parna dune thus far. Coring has documented a basal paleosol buried at a depth equivalent to the surrounding landscape—14C ages from this soil indicate its formation about 25-21 ka. The paleosol is a hydric Mollisol with a pronounced C3 isotopic signature reflecting hydric plant communities, rather than the regionally dominated C4 prairie vegetation. Hydric soils are associated with many of the playas on the surrounding landscape today, which suggests that they may have been more prevalent during the LGM. The overlying 8-10 m of parna is low in organic C and high in calcite, with indications of up to ten major episodes of sediment flux, which are documented with magnetic, isotope, soil-stratigraphic, particle-size, and color data. Near-surface luminescence (OSL) ages from Blue Mound are similar to the 14C ages from the basal paleosol, indicating rapid dune construction, with little or no Holocene accumulation of sediment. Marine isotope stage (MIS) 3 loess records indicate that upland areas of the region were relatively stable with attendant widespread pedogenesis prior to development of the parna dunes. At the onset of the LGM, however, the landscape destabilized, and aeolian processes dominated. Peoria Loess began accumulating throughout parts of Oklahoma and much of Kansas, Nebraska, and beyond, until landscape stabilization was re-attained about 14-13 ka. Our chronological and geomorphic data suggest that parna dune construction in the Oklahoma panhandle was the result of strong, northerly winds, which precipitated aeolian activity at the beginning of MIS 2. Furthermore, these features appear to be more analogous to the regional loess record than the sand dune activation record, and, with more research, may prove to be a reliable record of late-Quaternary landscape change in the central Great Plains.

Possible Impacts of the Invasive Plant Rubus niveus on the Native Vegetation of the Scalesia Forest in the Galapagos Islands

PubMed Central

Rentería, Jorge Luis; Gardener, Mark R.; Panetta, F. Dane; Atkinson, Rachel; Crawley, Mick J.

2012-01-01

Originally from Asia, Rubus niveus has become one of the most widespread invasive plant species in the Galapagos Islands. It has invaded open vegetation, shrubland and forest alike. It forms dense thickets up to 4 m high, appearing to displace native vegetation, and threaten the integrity of several native communities. This study used correlation analysis between a R. niveus cover gradient and a number of biotic (vascular plant species richness, cover and vegetation structure) and abiotic (light and soil properties) parameters to help understand possible impacts in one of the last remaining fragments of the Scalesia forest in Santa Cruz Island, Galapagos. Higher cover of R. niveus was associated with significantly lower native species richness and cover, and a different forest structure. Results illustrated that 60% R. niveus cover could be considered a threshold for these impacts. We suggest that a maximum of 40% R. niveus cover could be a suitable management target. PMID:23118934

Picking up the pieces: conserving remnant natural areas in the post-industrial landscape of the Calumet Region

USGS Publications Warehouse

Labus, Paul; Whitman, Richard L.; Nevers, Meredith Becker

1999-01-01

The Calumet Region was shaped by geologic forces, succession, and interacting biomes converging on a unique natural landscape. Over the past 4500 years, a strand plain has formed to the north of a geologic area called Toleston Beach. Sequential and differential primary succession of dune and swale communities in this region allowed species from different biomes to interact freely. In the mid-nineteenth century, commerce and settlement drastically changed the area, and natural areas were fragmented, manipulated, and degraded by cultural intrusions and industrialization. Despite the near obliteration of dune and swale habitat, small fragments of natural land escaped destruction. These native fragments maintained some semblance of the landscape that once covered the region. Currently, these native fragments are threatened by the lingering intrusion of historic contamination and the continuing presence of industry and commerce. Restoration and conservation of these remnants will need to be a process of integrating biological diversity goals into the landscape of the industrialized region through planning and design. We outline here the natural history of the region, the philosophical rationale for conservation, and possible approaches for integrating and maintaining these valuable remnant resources and processes.

Mediterranean coastal sand dune vegetation: influence of natural and anthropogenic factors.

PubMed

Ciccarelli, Daniela

2014-08-01

The aim of the present work was to assess the conservation status of coastal dune systems in Tuscany (Italy). Emphasis was given to the presence and abundance of plant communities identified as habitat in accordance with the Directive 92/43/EEC. Twenty transects perpendicular to the shoreline were randomly positioned on the whole coastal area (30 km in length) in order to sample the full spectrum of plant communities. Vegetation zonation and relationships with the most frequent disturbance factors in the study area-beach cleaning, coastline erosion, presence of paths and roads, bathing settlements and trampling-were investigated through principal coordinate analysis and canonical correspondence analysis. Natural factors, such as distance from the sea and total length, were also considered. Differences in the conservation status of the sites were found, ranging from the total disappearance of the foredune habitats to the presence of the complete psammophilous (sand-loving) plant communities. Erosion, trampling, and paths were found to be closely correlated with degradation and habitat loss. Furthermore, the overall plant species diversity of dunes was measured with NHDune, a modified version of the Shannon index; while the incidence of invasive taxa was calculated using N, a naturalness index. However, these diversity indices proved to be a weaker bioindicator of ecosystem integrity than habitat composition along transects. A possible strategy for the conservation and management of these coastal areas could be to protect the foredunes from erosion and limit trampling through the installation of footbridges or the use of appropriate fences.

Offsetting the impacts of mining to achieve no net loss of native vegetation.

PubMed

Sonter, L J; Barrett, D J; Soares-Filho, B S

2014-08-01

Offsets are a novel conservation tool, yet using them to achieve no net loss of biodiversity is challenging. This is especially true when using conservation offsets (i.e., protected areas) because achieving no net loss requires avoiding equivalent loss. Our objective was to determine if offsetting the impacts of mining achieves no net loss of native vegetation in Brazil's largest iron mining region. We used a land-use change model to simulate deforestation by mining to 2020; developed a model to allocate conservation offsets to the landscape under 3 scenarios (baseline, no new offsets; current practice, like-for-like [by vegetation type] conservation offsetting near the impact site; and threat scenario, like-for-like conservation offsetting of highly threatened vegetation); and simulated nonmining deforestation to 2020 for each scenario to quantify avoided deforestation achieved with offsets. Mines cleared 3570 ha of native vegetation by 2020. Under a 1:4 offset ratio, mining companies would be required to conserve >14,200 ha of native vegetation, doubling the current extent of protected areas in the region. Allocating offsets under current practice avoided deforestation equivalent to 3% of that caused by mining, whereas allocating under the threat scenario avoided 9%. Current practice failed to achieve no net loss because offsets did not conserve threatened vegetation. Explicit allocation of offsets to threatened vegetation also failed because the most threatened vegetation was widely dispersed across the landscape, making conservation logistically difficult. To achieve no net loss with conservation offsets requires information on regional deforestation trajectories and the distribution of threatened vegetation. However, in some regions achieving no net loss through conservation may be impossible. In these cases, other offsetting activities, such as revegetation, will be required. © 2014 Society for Conservation Biology.

Ecological niche modeling of coastal dune plants and future potential distribution in response to climate change and sea level rise.

PubMed

Mendoza-González, Gabriela; Martínez, M Luisa; Rojas-Soto, Octavio R; Vázquez, Gabriela; Gallego-Fernández, Juan B

2013-08-01

Climate change (CC) and sea level rise (SLR) are phenomena that could have severe impacts on the distribution of coastal dune vegetation. To explore this we modeled the climatic niches of six coastal dunes plant species that grow along the shoreline of the Gulf of Mexico and the Yucatan Peninsula, and projected climatic niches to future potential distributions based on two CC scenarios and SLR projections. Our analyses suggest that distribution of coastal plants will be severely limited, and more so in the case of local endemics (Chamaecrista chamaecristoides, Palafoxia lindenii, Cakile edentula). The possibilities of inland migration to the potential 'new shoreline' will be limited by human infrastructure and ecosystem alteration that will lead to a 'coastal squeeze' of the coastal habitats. Finally, we identified areas as future potential refuges for the six species in central Gulf of Mexico, and northern Yucatán Peninsula especially under CC and SLR scenarios. © 2013 John Wiley & Sons Ltd.

Environmental processes and spectral reflectance characteristics associated with soil erosion in desert fringe regions

NASA Technical Reports Server (NTRS)

Jacobberger, P. A.

1986-01-01

Two Thematic Mapper (TM) scenes were acquired. A scene was acquired for the Bahariya, Egypt field area, and one was acquired covering the Okavango Delta site. Investigations at the northwest Botswana study sites have concentrated upon a system of large linear (alab) dunes possessing an average wavelength of 2 kilometers and an east-west orientation. These dunes exist to the north and west of the Okavango Swamp, the pseudodeltaic end-sink of the internal Okavango-Cubango-Cuito drainage network. One archival scene and two TM acquisitions are on order, but at present no TM data were acquired for the Tombouctou/Azaouad Dunes, Mali. The three areas taken together comprise an environmental series ranging from hyperarid to semi-arid, with desertization processes operational or incipient in each. The long range goal is to predict normal seasonal variations, so that aperiodic spectral changes resulting from soil erosion, vegetation damage, and associated surface processes would be distinguishable as departures from the norm.

Native plant recovery in study plots after fennel (Foeniculum vulgare) control on Santa Cruz Island

USGS Publications Warehouse

Power, Paula; Stanley, Thomas R.; Cowan, Clark; Robertson, James R.

2014-01-01

Santa Cruz Island is the largest of the California Channel Islands and supports a diverse and unique flora which includes 9 federally listed species. Sheep, cattle, and pigs, introduced to the island in the mid-1800s, disturbed the soil, browsed native vegetation, and facilitated the spread of exotic invasive plants. Recent removal of introduced herbivores on the island led to the release of invasive fennel (Foeniculum vulgare), which expanded to become the dominant vegetation in some areas and has impeded the recovery of some native plant communities. In 2007, Channel Islands National Park initiated a program to control fennel using triclopyr on the eastern 10% of the island. We established replicate paired plots (seeded and nonseeded) at Scorpion Anchorage and Smugglers Cove, where notably dense fennel infestations (>10% cover) occurred, to evaluate the effectiveness of native seed augmentation following fennel removal. Five years after fennel removal, vegetative cover increased as litter and bare ground cover decreased significantly (P < 0.0001) on both plot types. Vegetation cover of both native and other (nonfennel) exotic species increased at Scorpion Anchorage in both seeded and nonseeded plots. At Smugglers Cove, exotic cover decreased significantly (P = 0.0001) as native cover comprised of Eriogonum arborescensand Leptosyne gigantea increased significantly (P < 0.0001) in seeded plots only. Nonseeded plots at Smugglers Cove were dominated by exotic annual grasses, primarily Avena barbata. The data indicate that seeding with appropriate native seed is a critical step in restoration following fennel control in areas where the native seed bank is depauperate.

Advanced Interferometric Synthetic Aperture Imaging Radar (InSAR) for Dune Mapping

NASA Astrophysics Data System (ADS)

Havivi, Shiran; Amir, Doron; Schvartzman, Ilan; August, Yitzhak; Mamman, Shimrit; Rotman, Stanely R.; Blumberg, Dan G.

2016-04-01

Aeolian morphologies are formed in the presence of sufficient wind energy and available lose particles. These processes occur naturally or are further enhanced or reduced by human intervention. The dimensions of change are dependent primarily on the wind energy and surface properties. Since the 1970s, remote sensing imagery, both optical and radar, have been used for documentation and interpretation of the geomorphologic changes of sand dunes. Remote sensing studies of aeolian morphologies is mostly useful to document major changes, yet, subtle changes, occurring in a period of days or months in scales of centimeters, are very difficult to detect in imagery. Interferometric Synthetic Aperture Radar (InSAR) is an imaging technique for measuring Earth's surface topography and deformation. InSAR images are produced by measuring the radar phase difference between two separated antennas that view the same surface area. Classical InSAR is based on high coherence between two or more images. The output (interferogram) can show subtle changes with an accuracy of several millimeters to centimeters. Very little work has been done on measuring or identifying the changes in dunes using InSAR methods. The reason is that dunes tend to be less coherent than firm, stable, surfaces. This work aims to demonstrate how interferometric decorrelation can be used for identifying dune instability. We hypothesize and demonstrate that the loss of radar coherence over time on dunes can be used as an indication of the dune's instability. When SAR images are acquired at sufficiently close intervals one can measure the time it takes to lose coherence and associate this time with geomorphic stability. To achieve our goals, the coherence change detection method was used, in order to identify dune stability or instability and the dune activity level. The Nitzanim-Ashdod coastal dunes along the Mediterranean, 40 km south of Tel-Aviv, Israel, were chosen as a case study. The dunes in this area are of varying levels of stability and vegetation cover and have been monitored meteorologically, geomorphologically, and studied extensively in the field. High resolution TerraSAR-X (TSX) images covering the entire research area were acquired for the period of 2011 to 2012. Analysis was performed in imaging processing and GIS software. The coherence results display minor changes on the dune crest (0.42-0.49), compared to bigger changes in windward slope (0.31-0.37). The level of change depends on the dune location relative to its distance from the sea. Furthermore, the coherence results show decreasing over time. Field results indicate erosion/deposition of sand ranging from -99 to 137 mm/year. The results of this study confirm that it is possible to monitor subtle changes in sand dunes and to identify dune stability or instability, only by the use of SAR images, even in areas characterized by low coherence.

Advanced InSAR imaging for dune mapping

NASA Astrophysics Data System (ADS)

Havivi, Shiran; August, Yitzhak; Blumberg, Dan G.; Rotman, Stanley R.

2015-04-01

Aeolian morphologies are formed in the presence of sufficient wind energy and available particles. These processes occur naturally or are further enhanced or reduced by human intervention. The dimensions of change are dependent primarily on the wind energy and surface properties. Since the 1970's, remote sensing imagery both optical and radar, are used for documentation and interpretation of the geomorphologic changes of sand dunes. Remote sensing studies of Aeolian morphologies is mostly useful to document major changes, yet, subtle changes, occurring in a period of days or months in scales of centimeters, are very difficult to detect in imagery. Interferometric Synthetic Aperture Radar (InSAR) is an imaging technique for measuring Earth's surface topography and deformation. InSAR images are produced by measuring the radar phase difference between two separated antennas that view the same surface area. Classical InSAR is based on high coherence between two images or more. The output (interferogram) can show subtle changes with an accuracy of several millimeters to centimeters. Very little work has been done on measuring or identifying the changes in dunes using InSAR. The reason is that dunes tend to be less coherent than firm, stable, surfaces. This research aims to demonstrate how interferometric decorrelation, or, coherence change detection, can be used for identifying dune instability. We hypothesize and demonstrate that the loss of radar coherence over time on dunes can be used as an indication of the dune's instability. When SAR images are acquired at sufficiently close intervals one can measure the time it takes to lose coherence and associate this time with geomorphic stability. To achieve our goals, the Nitzanim coastal dunes along the Mediterranean, 40 km south of Tel-Aviv, Israel, were chosen as a case study. The dunes in this area are of varying levels of stability and vegetation cover and have been monitored meteorologically, geomorphologically and extensively in the field. High resolution TerraSAR-X (TSX) images, covering the entire research area were acquired for the period of October 2011 to July 2012 (15 images in total). All images were co-registreted, the first image was used as the master image. A coherence index was calculated for all the images. Analysis was performed in GIS software. The results display minor changes (coherence index in range of 0.4-0.65) on dune crests depending on the dune location relative to its distance from the sea and distance from the city. In addition, field results indicate erosion / deposition of sand in a cumulatively amount of approximately 30mm annually. The results of this study confirm that it is possible to monitor subtle changes in dunes and to identify dune stability or instability, only by the use of SAR images.

SEASONAL AND DIURNAL ACTIVITY PATTERNS IN ANT (HYMENOPTERA: FORMICIDAE) COMMUNITIES IN A VEGETATION TRANSITION REGION OF SOUTHEASTERN NEW MEXICO

EPA Science Inventory

The densities of active ant colonies were estimated in three habitats: creosotebush shrubland, grassland, and shinnery-oak mesquite dunes. Diurnal foraging patterns were studied at bait boards. Species richness of ant communities in this transitional region (8-12 species) was co...

Microbial Communities in Cerrado Soils under Native Vegetation Subjected to Prescribed Fires and Under Pasture

EPA Science Inventory

The objective of this work was to evaluate the effects of fire regimes and vegetation cover on the structure and dynamics of soil microbial communities, through phospholipid fatty acid (PLFA) analysis. Comparisons were made between native areas with different woody covers ("cerra...

Invasive species compendium: Salvinia molesta D.S. Mitchell

USDA-ARS?s Scientific Manuscript database

Salvinia molesta D.S. Mitchell is an invasive aquatic fern native to a small area of south-eastern Brazil. It has spread throughout the world, forming thick mats of vegetation that decrease dissolved oxygen and pH while outcompeting native vegetation. It has been introduced and established into many...

Status of biological control in vegetation management in forestry

Treesearch

George P. Markin; Donald E. Gardner

1993-01-01

Biological control traditionally depends upon importing the natural enemies of introduced weeds. Since vegetation management in forestry has primarily been aimed at protecting economic species of trees from competition from other native plants, biological control has been of little use in forestry. An alternative approach to controlling unwanted native plants,...

Phenology of perennial native grass below-ground axillary buds in the northern mixed-grass prairie

USDA-ARS?s Scientific Manuscript database

Vegetative reproduction from belowground bud banks is the primary driver of grassland systems. Despite the importance of vegetative reproduction, the timing of belowground bud recruitment is unknown for most dominant, perennial native grasses as is the relationship between bud development and envir...

Soil, vegetation, and seed bank of a Sonoran Desert ecosystem along an exotic plant (Pennisetum ciliare) treatment gradient.

PubMed

Abella, Scott R; Chiquoine, Lindsay P; Backer, Dana M

2013-10-01

Ecological conditions following removal of exotic plants are a key part of comprehensive environmental management strategies to combat exotic plant invasions. We examined ecological conditions following removal of the management-priority buffelgrass (Pennisetum ciliare) in Saguaro National Park of the North American Sonoran Desert. We assessed soil, vegetation, and soil seed banks on seven buffelgrass site types: five different frequencies of buffelgrass herbicide plus hand removal treatments (ranging from 5 years of annual treatment to a single year of treatment), untreated sites, and non-invaded sites, with three replicates for each of the seven site types. The 22 measured soil properties (e.g., pH) differed little among sites. Regarding vegetation, buffelgrass cover was low (≤1% median cover), or absent, across all treated sites but was high (10-70%) in untreated sites. Native vegetation cover, diversity, and composition were indistinguishable across site types. Species composition was dominated by native species (>93% relative cover) across all sites except untreated buffelgrass sites. Most (38 species, 93%) of the 41 species detected in soil seed banks were native, and native seed density did not differ significantly across sites. Results suggest that: (1) buffelgrass cover was minimal across treated sites; (2) aside from high buffelgrass cover in untreated sites, ecological conditions were largely indistinguishable across sites; (3) soil seed banks harbored ≥12 species that were frequent in the aboveground vegetation; and (4) native species dominated post-treatment vegetation composition, and removing buffelgrass did not result in replacement by other exotic species.

Soil, Vegetation, and Seed Bank of a Sonoran Desert Ecosystem Along an Exotic Plant ( Pennisetum ciliare) Treatment Gradient

NASA Astrophysics Data System (ADS)

Abella, Scott R.; Chiquoine, Lindsay P.; Backer, Dana M.

2013-10-01

Ecological conditions following removal of exotic plants are a key part of comprehensive environmental management strategies to combat exotic plant invasions. We examined ecological conditions following removal of the management-priority buffelgrass ( Pennisetum ciliare) in Saguaro National Park of the North American Sonoran Desert. We assessed soil, vegetation, and soil seed banks on seven buffelgrass site types: five different frequencies of buffelgrass herbicide plus hand removal treatments (ranging from 5 years of annual treatment to a single year of treatment), untreated sites, and non-invaded sites, with three replicates for each of the seven site types. The 22 measured soil properties (e.g., pH) differed little among sites. Regarding vegetation, buffelgrass cover was low (≤1 % median cover), or absent, across all treated sites but was high (10-70 %) in untreated sites. Native vegetation cover, diversity, and composition were indistinguishable across site types. Species composition was dominated by native species (>93 % relative cover) across all sites except untreated buffelgrass sites. Most (38 species, 93 %) of the 41 species detected in soil seed banks were native, and native seed density did not differ significantly across sites. Results suggest that: (1) buffelgrass cover was minimal across treated sites; (2) aside from high buffelgrass cover in untreated sites, ecological conditions were largely indistinguishable across sites; (3) soil seed banks harbored ≥12 species that were frequent in the aboveground vegetation; and (4) native species dominated post-treatment vegetation composition, and removing buffelgrass did not result in replacement by other exotic species.

Resilience of Invaded Riparian Landscapes: The Potential Role of Soil-Stored Seed Banks

NASA Astrophysics Data System (ADS)

Tererai, Farai; Gaertner, Mirijam; Jacobs, Shayne M.; Richardson, David M.

2015-01-01

We investigated the potential role of soil-stored seed banks in driving vegetation recovery under varying intensities of invasion by the alien tree Eucalyptus camaldulensis along the Berg River in South Africa's Western Cape Province. We asked: How do richness, diversity, and composition of soil-stored seed banks vary with invasion intensity? What is the difference between the seed banks and above-ground vegetation with respect to species richness, diversity, composition, and structure? To what extent do soil-stored seed banks provide reliable sources for restoring native plant communities? Through a seedling-emergence approach, we compared seedling density, richness, and diversity in plots under varying Eucalyptus cover. Seed bank characteristics were also compared with those of the above-ground vegetation. Except in terms of diversity and density, the richness and composition of native species varied significantly among invasion conditions. Despite the paucity of native tree and shrub species in the seed bank, it was more diverse than extant vegetation. Some species occurred exclusively either in the seed bank or in the above-ground vegetation. Although this ecosystem has been degraded by several agents, including Eucalyptus invasion, soil-stored seed banks still offer modest potential for driving regeneration of native plant communities, but secondary invasions need to be managed carefully. Remnant populations of native plants in the above-ground vegetation remaining after E. camaldulensis clearing provide a more promising propagule source for rapid regeneration. Further work is needed to elucidate possible effects of invasion on successional pathways following E. camaldulensis removal and the effects of hydrochory on seed bank dynamics.

Food availability in exotic grasslands: a potential mechanism for depauperate breeding assemblages

USGS Publications Warehouse

George, Andrew D.; O'Connell, Timothy J.; Hickman, Karen R.; Leslie, David M.

2013-01-01

We investigated the influence of Old World bluestem (Bothriochloa ischaemum; OWB) monocultures on grassland bird abundance through analysis of vegetation structure and food availability. We compared breeding bird density, vegetation structure and composition, and arthropod biomass between six native grass and six OWB fields in the southern Great Plains. The OWB fields supported 1.70 ± 0.27 (mean ± SE) Grasshopper Sparrows (Ammodramus savannarum) per ha compared to 0.95 ± 0.25 in native grass fields, but total species richness was greater in native grass fields (40 versus 28 species). Density of some bird species was correlated with vegetation structure regardless of field type, suggesting that management practices may be more influential than plant species composition. Mean arthropod biomass was 3.39× greater in native grass fields than in OWB monocultures. Native grass fields provided habitat for a larger complement of birds than did OWB monocultures, and reduced food availability in OWB fields suggests a mechanism for that difference.

Spatial Heterogeneity of Soil Nutrients after the Establishment of Caragana intermedia Plantation on Sand Dunes in Alpine Sandy Land of the Tibet Plateau

PubMed Central

Li, Qingxue; Jia, Zhiqing; Zhu, Yajuan; Wang, Yongsheng; Li, Hong; Yang, Defu; Zhao, Xuebin

2015-01-01

The Gonghe Basin region of the Tibet Plateau is severely affected by desertification. Compared with other desertified land, the main features of this region is windy, cold and short growing season, resulting in relatively difficult for vegetation restoration. In this harsh environment, identification the spatial distribution of soil nutrients and analysis its impact factors after vegetation establishment will be helpful for understanding the ecological relationship between soil and environment. Therefore, in this study, the 12-year-old C. intermedia plantation on sand dunes was selected as the experimental site. Soil samples were collected under and between shrubs on the windward slopes, dune tops and leeward slopes with different soil depth. Then analyzed soil organic matter (SOM), total nitrogen (TN), total phosphorus (TP), total potassium (TK), available nitrogen (AN), available phosphorus (AP) and available potassium (AK). The results showed that the spatial heterogeneity of soil nutrients was existed in C. intermedia plantation on sand dunes. (1) Depth was the most important impact factor, soil nutrients were decreased with greater soil depth. One of the possible reasons is that windblown fine materials and litters were accumulated on surface soil, when they were decomposed, more nutrients were aggregated on surface soil. (2) Topography also affected the distribution of soil nutrients, more soil nutrients distributed on windward slopes. The herbaceous coverage were higher and C. intermedia ground diameter were larger on windward slopes, both of them probably related to the high soil nutrients level for windward slopes. (3) Soil “fertile islands” were formed, and the “fertile islands” were more marked on lower soil nutrients level topography positions, while it decreased towards higher soil nutrients level topography positions. The enrichment ratio (E) for TN and AN were higher than other nutrients, most likely because C. intermedia is a leguminous shrub. PMID:25946170

Spatial Heterogeneity of Soil Nutrients after the Establishment of Caragana intermedia Plantation on Sand Dunes in Alpine Sandy Land of the Tibet Plateau.

PubMed

Li, Qingxue; Jia, Zhiqing; Zhu, Yajuan; Wang, Yongsheng; Li, Hong; Yang, Defu; Zhao, Xuebin

2015-01-01

The Gonghe Basin region of the Tibet Plateau is severely affected by desertification. Compared with other desertified land, the main features of this region is windy, cold and short growing season, resulting in relatively difficult for vegetation restoration. In this harsh environment, identification the spatial distribution of soil nutrients and analysis its impact factors after vegetation establishment will be helpful for understanding the ecological relationship between soil and environment. Therefore, in this study, the 12-year-old C. intermedia plantation on sand dunes was selected as the experimental site. Soil samples were collected under and between shrubs on the windward slopes, dune tops and leeward slopes with different soil depth. Then analyzed soil organic matter (SOM), total nitrogen (TN), total phosphorus (TP), total potassium (TK), available nitrogen (AN), available phosphorus (AP) and available potassium (AK). The results showed that the spatial heterogeneity of soil nutrients was existed in C. intermedia plantation on sand dunes. (1) Depth was the most important impact factor, soil nutrients were decreased with greater soil depth. One of the possible reasons is that windblown fine materials and litters were accumulated on surface soil, when they were decomposed, more nutrients were aggregated on surface soil. (2) Topography also affected the distribution of soil nutrients, more soil nutrients distributed on windward slopes. The herbaceous coverage were higher and C. intermedia ground diameter were larger on windward slopes, both of them probably related to the high soil nutrients level for windward slopes. (3) Soil "fertile islands" were formed, and the "fertile islands" were more marked on lower soil nutrients level topography positions, while it decreased towards higher soil nutrients level topography positions. The enrichment ratio (E) for TN and AN were higher than other nutrients, most likely because C. intermedia is a leguminous shrub.

Impact analysis of off-road-vehicle use on vegetation in the Grand Mere dune environment. [Lake Michigan

NASA Technical Reports Server (NTRS)

Schultink, G. (Principal Investigator)

1977-01-01

The author has identified the following significant results. A linear regression between percent nonvegetative land and the time variable was completed for the two sample areas. Sample area no. 1 showed an average vegetation loss of 1.901% per year, while the loss for sample area no. 2 amounted to 5.889% per year. Two basic reasons for the difference were assumed to play a role: the difference in access potential and the amount of already fragmented vegetation complexes in existence during the first year of the comparative analysis - 1970. Sample area no. 2 was located closer to potential access points and was more fragmented initially.

Natural and human controls of the Holocene evolution of the beach, aeolian sand and dunes of Caesarea (Israel)

NASA Astrophysics Data System (ADS)

Roskin, J.; Sivan, D.; Shtienberg, G.; Roskin, E.; Porat, N.; Bookman, R.

2015-12-01

The study focuses on the Holocene appearance, chronology and drivers of beach sand deposition and inland aeolian sand transport around the Roman-Byzantine ruins of Caesarea, Israel. Beach sand, sand sheets, nebkha, linear and transverse dunes as well as parabolic and transverse interdunes along two transects were sampled in the current study down to their substrate. Sixteen new optically stimulated luminescence ages cluster at ∼5.9-3.3 ka, ∼1.2-1.1 ka (800-900 AD) and ∼190-120 years ago (1825-1895 AD) indicating times of middle and late Holocene sand sheet depositions and historical dune stabilization. The first age cluster indicates that beach sand accumulated when rates of global sea level rise declined around 6-5 ka. Until ∼4 ka sand sheets encroached up to 2.5 km inland. Historical and archaeological evidence points to sand mobilization since the first century AD. Sand sheets dating to 1.2-1.1 ka, coevally found throughout the dunefield represent sand stabilization due to vegetation reestablishment attributed to gradual and fluctuating decline in human activity from the middle Early Islamic period until the 10th century. Historical and chronological evidence of the existence of transverse and coppice dunes from the 19th century suggest that dunes only formed in the last few centuries. The study illustrates the initial role of natural processes, in this case decline in global sea level rise and the primary and later role of fluctuating human activity upon coastal sand mobility. The study distinguishes between sand sheets and dunes and portrays them as sensors of environmental changes.

Biological Soil Crusts from Coastal Dunes at the Baltic Sea: Cyanobacterial and Algal Biodiversity and Related Soil Properties.

PubMed

Schulz, Karoline; Mikhailyuk, Tatiana; Dreßler, Mirko; Leinweber, Peter; Karsten, Ulf

2016-01-01

Biological soil crusts (BSCs) are known as "ecosystem-engineers" that have important, multifunctional ecological roles in primary production, in nutrient and hydrological cycles, and in stabilization of soils. These communities, however, are almost unstudied in coastal dunes of the temperate zone. Hence, for the first time, the biodiversity of cyanobacterial and algal dominated BSCs collected in five dunes from the southern Baltic Sea coast on the islands Rügen and Usedom (Germany) was investigated in connection with physicochemical soil parameters. The species composition of cyanobacteria and algae was identified with direct determination of crust subsamples, cultural methods, and diatom slides. To investigate the influence of soil properties on species composition, the texture, pH, electrical conductivity, carbonate content, total contents of carbon, nitrogen, phosphorus, and the bioavailable phosphorus-fraction (PO4 (3-)) were analyzed in adjacent BSC-free surface soils at each study site. The data indicate that BSCs in coastal dunes of the southern Baltic Sea represent an ecologically important vegetation form with a surprisingly high site-specific diversity of 19 cyanobacteria, 51 non-diatom algae, and 55 diatoms. All dominant species of the genera Coleofasciculus, Lyngbya, Microcoleus, Nostoc, Hydrocoryne, Leptolyngbya, Klebsormidium, and Lobochlamys are typical aero-terrestrial cyanobacteria and algae, respectively. This first study of coastal sand dunes in the Baltic region provides compelling evidence that here the BSCs were dominated by cyanobacteria, algae, or a mixture of both. Among the physicochemical soil properties, the total phosphorus content of the BSC-free sand was the only factor that significantly influenced the cyanobacterial and algal community structure of BSCs in coastal dunes.

Native Grasses as a Management Alternative on Vegetated Closure Caps

NASA Astrophysics Data System (ADS)

Kwit, Charles; Collins, Beverly

2008-06-01

Capped waste sites often are vegetated with commercial turf grasses to increase evapotranspiration and prevent erosion and possible exposure of the barrier. Fertilizer, frequent watering, and mowing may be required to establish the turf grass and prevent invasion by trees and shrubs. Oldfield vegetation of grasses and forbs is a possible sustainable alternative to turf grass communities. To determine if oldfield vegetation can establish on caps, we (1) compared establishment of a dominant oldfield grass and a commercial turf grass under different combinations of new closure cap management: spring or summer planting and presence or absence of amendments to alleviate drought (watering, mulch) or increase soil fertility (fertilizer, lime, a nitrogen-fixing legume); (2) surveyed existing caps to determine if oldfield species establish naturally; and (3) performed a greenhouse experiment to compare growth of two native grasses under low and amended (added water, soil nutrients) conditions. Both the commercial grass and oldfield species established under new cap conditions; fertilizer, water, and mulch improved vegetation establishment in spring or summer, but legumes decreased grass cover. In the greenhouse, both native grasses grew best with amendments; however, substantial stem and root length were obtained with no fertilizer and only once-weekly watering. Existing vegetated caps supported planted grasses and naturally established oldfield species. Overall, the results indicate native grasses can establish on new caps and oldfields can serve as a management model; further work is needed to determine the management strategy to maintain herbaceous vegetation and slow woody species invasion.

Human disturbance and stage-specific habitat requirements influence snowy plover site occupancy during the breeding season

PubMed Central

Webber, Alyson F; Heath, Julie A; Fischer, Richard A

2013-01-01

Habitat use has important consequences for avian reproductive success and survival. In coastal areas with recreational activity, human disturbance may limit use of otherwise suitable habitat. Snowy plovers Charadrius nivosus have a patchy breeding distribution along the coastal areas on the Florida Panhandle, USA. Our goal was to determine the relative effects of seasonal human disturbance and habitat requirements on snowy plover habitat use. We surveyed 303 sites for snowy plovers, human disturbance, and habitat features between January and July 2009 and 2010. We made multiple visits during three different sampling periods that corresponded to snowy plover breeding: pre-breeding, incubation, and brood-rearing and used multi-season occupancy models to examine whether human disturbance, habitat features, or both influenced site occupancy, colonization (probability of transition from an unoccupied site to an occupied site), and extinction (probability of transition from an occupied site to an unoccupied site). Snowy plover site occupancy and colonization was negatively associated with human disturbance and site extinction was positively associated with human disturbance. Interdune vegetation had a negative effect on occupancy and colonization, indicating that plovers were less likely to use areas with uniform, dense vegetation among dunes. Also, dune shape, beach debris, and access to low-energy foraging areas influenced site occupancy, colonization, and extinction. Plovers used habitat based on beach characteristics that provided stage-specific resource needs; however, human disturbance was the strongest predictor of site occupancy. In addition, vegetation plantings used to enhance dune rehabilitation may negatively impact plover site occupancy. Management actions that decrease human disturbance, such as symbolic fencing and signage, may increase the amount of breeding habitat available to snowy plovers on the Florida Panhandle and in other areas with high human activity. The specific areas that require this protection may vary across snowy plover life history stages. PMID:23610630

Biological-Physical Feedbacks Determine Coastal Environmental Response to Climate Change

NASA Astrophysics Data System (ADS)

Moore, L. J.; Duran Vinent, O.; Walters, D.; Fagherazzi, S.; Mariotti, G.; Young, D.; Wolner, C. V.

2012-12-01

As low-lying coastal landforms, transitional between marine and terrestrial realms, barrier islands are especially sensitive to changing environmental conditions. Interactions among biological and physical processes appear to play a critical role in determining how these landscapes will evolve in the future as sea level rises, storm intensity increases and plant species composition changes. Within a new conceptual framework, barrier islands tend to exist in one of two primary states. "Low" islands have little relief above sea level and are dominated by external processes, responding quickly on short time scales to changes in forcing (e.g., storms, sea level rise, etc.), migrating rapidly and generally being low in ecological diversity and productivity. In contrast, "high" islands are less vulnerable to storms, tend to be dominated by internal processes (e.g., sand trapping by vegetation), require long time periods to respond to changes in forcing, migrate slowly (if at all) and host a range of plant species and morphological environments including shrubs, small trees and vegetated secondary and tertiary dunes with intervening swales. The continued existence of barrier island landforms will depend on the degree to which islands can maintain elevation above sea level while also responding to changes in forcing by migrating landward. A long-term morphological-behavior model exploring coupled barrier-marsh evolution and a new ecomorphodynamic model representing the formation/recovery of dunes as a function of storms, shed light on the role of interactions among biological and physical processes on barrier island response to climate change. Results suggest that connections between the marsh and barrier realms, which are mediated by biological processes in the marsh environment, are highly sensitive to factors such as sea level rise rate, antecedent morphology and marsh composition. Results also suggest that feedbacks between sediment transport and vegetation involved in dune building may allow small, gradual changes in storms to cause abrupt, nonlinear transitions from the high to low island state.

Inland aeolian deposits of the Iberian Peninsula: Sand dunes and clay dunes of the Duero Basin and the Manchega Plain. Palaeoclimatic considerations

NASA Astrophysics Data System (ADS)

Bernat Rebollal, M.; Pérez-González, A.

2008-12-01

This paper describes the latest research on the geomorphological characteristics, formation environment and chronology of the main inland aeolian deposits from the south-eastern Duero Basin (DB) and the Manchega Plain (MP) of the Iberian Peninsula. Similarities and differences between the aeolian deposits of these two locations are summarised. Wind deflation from the Guadiana and Júcar alluvial systems created the aeolian deposits of the MP. These deposits are mainly composed of quartz sands. However, in the San Juan alluvial plain (MP) there is a large extent of clay dunes formed by exposure to prevalent winds of seasonal playa-lakes with salt and clay sediments. In the DB, wind remobilisation of the small particles from Quaternary terraces and Tertiary arkosic sediments left aeolian deposits of quartz-feldspar sands. Textural parameters of the aeolian deposits show large variations depending on the location and the original deposit. Thus, in the DB the aeolian sands derived from the deflation of fluvial sediments are better sorted and smaller in grain size than those created by the deflation of arkosic sediments. Morphologically, simple and compound parabolic dunes (U-V forms, hemicyclic, lobate and elongate), crescentic and linear dunes, climbing dunes and blowout dunes have been recognized at both sites. Barchan and dome dunes are present only in the DB while "lunette lunette-clay dunes" are found only in the MP. In both locations, the large extent of aeolian sand sheets and the predominance of simple and compound parabolic dunes indicates the active role of sparse vegetation cover in the formation of this aeolian system. In the DB, dunes were formed by southwest and west winds, while in the MP the aeolian morphologies indicate that the prevalent winds were west and northwest. The chronology of the dune deposits is being determined with luminescence (TL-OSL) dating and Mass Spectrometry Analysis ( 14C-AMS). In this way, the aeolian activity and stabilisation stages can be established, the latter well marked in the DB through soil A horizon development. Thus, the main sand dune formation in the DB and the eastern regions of the MP occurred between 13.5 and 7 ka BP, during the cold and arid Younger Dryas episode and the Early Holocene. The clay dunes of the MP accumulated mainly from 29 to 19 ka BP that corresponds with Heinrich events HE-3 and HE-2 and the Last Glacial Maximum. However, clay dunes were also formed between 13.5 and 7 ka BP. In both locations, there have been reactivations of some sand deposits in the recent Holocene, with maximum activity around 5-2 ka BP and 0.5-0.2 ka BP. On the other hand, three marked stages of stabilisation of the DB aeolian system have been established with 14C-AMS, around 10.2, 6.2 and 1.2 ka BP. Finally, the main winds contributing to dune construction were also responsible for the deflation processes with the formation of erosional depressions.

Non-native plants and wildlife in the Intermountain West

Treesearch

Andrea R. Litt; Dean E. Pearson

2013-01-01

Non-native plant invasions can change communities and ecosystems by altering the structure and composition of native vegetation. Changes in native plant communities caused by non-native plants can influence native wildlife species in diverse ways, but the outcomes and underlying mechanisms are poorly understood. Here, we review and synthesize current information for...

Automated Feature Extraction of Foredune Morphology from Terrestrial Lidar Data

NASA Astrophysics Data System (ADS)

Spore, N.; Brodie, K. L.; Swann, C.

2014-12-01

Foredune morphology is often described in storm impact prediction models using the elevation of the dune crest and dune toe and compared with maximum runup elevations to categorize the storm impact and predicted responses. However, these parameters do not account for other foredune features that may make them more or less erodible, such as alongshore variations in morphology, vegetation coverage, or compaction. The goal of this work is to identify other descriptive features that can be extracted from terrestrial lidar data that may affect the rate of dune erosion under wave attack. Daily, mobile-terrestrial lidar surveys were conducted during a 6-day nor'easter (Hs = 4 m in 6 m water depth) along 20km of coastline near Duck, North Carolina which encompassed a variety of foredune forms in close proximity to each other. This abstract will focus on the tools developed for the automated extraction of the morphological features from terrestrial lidar data, while the response of the dune will be presented by Brodie and Spore as an accompanying abstract. Raw point cloud data can be dense and is often under-utilized due to time and personnel constraints required for analysis, since many algorithms are not fully automated. In our approach, the point cloud is first projected into a local coordinate system aligned with the coastline, and then bare earth points are interpolated onto a rectilinear 0.5 m grid creating a high resolution digital elevation model. The surface is analyzed by identifying features along each cross-shore transect. Surface curvature is used to identify the position of the dune toe, and then beach and berm morphology is extracted shoreward of the dune toe, and foredune morphology is extracted landward of the dune toe. Changes in, and magnitudes of, cross-shore slope, curvature, and surface roughness are used to describe the foredune face and each cross-shore transect is then classified using its pre-storm morphology for storm-response analysis.

Terraforming planet Dune: Climate-vegetation interactions on a sandy planet

NASA Astrophysics Data System (ADS)

Cresto Aleina, F.; Baudena, M.; D'Andrea, F.; Provenzale, A.

2012-04-01

The climate and the biosphere of planet Earth interact in multiple, complicated ways and on many spatial and temporal scales. Some of these processes can be studied with the help of simple mathematical models, as done for the effects of vegetation on albedo in desert areas and for the mechanisms by which terrestrial vegetation affects water fluxes in arid environments. Conceptual models of this kind do not attempt at providing quantitative descriptions of the climate-biosphere interaction, but rather to explore avenues and mechanisms which can play a role in the real system, providing inspiration for further research. In this work, we develop a simple conceptual box model in the spirit illustrated above, to explore whether and how vegetation affects the planetary hydrologic cycle. We imagine a planet with no oceans and whose surface is entirely covered with sand, quite similar to planet Dune of the science-fiction series by Frank Herbert (1965). We suppose that water is entirely in the sand, below the surface. Without vegetation, only evaporation takes place, affecting the upper sand layer for a maximum depth of a few cm. The amount of water that is evaporated in the atmosphere is relatively small, and not sufficient to trigger a full hydrologic cycle. The question is what happens to this planet when vegetation is introduced: the root depth can reach a meter or more, and plant transpiration can then transfer a much larger amount of water to the atmosphere. One may wonder whether the presence of vegetation is sufficient to trigger a hydrologic cycle with enough precipitation to sustain the vegetation itself and, if the answer is positive, what is the minimum vegetation cover that is required to maintain the cycle active. In more precise terms, we want to know whether the introduction of vegetation and of the evapotranspiration feedback allows for the existence of multiple equilibria (or solutions) in the soil-vegetation-atmosphere system. Although the box model introduced here is best formulated in terms of a hypothetical sandy planet, the results can be used to study the hydrologic cycle on wide continental regions of the Earth. On the other hand, our findings show how the definition of a habitable climate may also depend on surface characteristics, and in particular on biosphere and climate interactions.

EFFECTS OF CLIMATE CHANGE ON VEGETATION AND ECOSYSTEM SERVICES IN THE COLORADO FRONT RANGE

EPA Science Inventory

If climate change leads to an extended growing season and somewhat wetter winters in the Front Range of Colorado, then a new time period of resource availability will be created. Non-native vegetation whose native lands possessed climates similar to the “new conditions” may be...

Native herbivore exerts contrasting effects on fire regime and vegetation structure

Treesearch

Jose L. Hierro; Kenneth L. Clark; Lyn C. Branch; Diego Villarreal

2011-01-01

Although native herbivores can alter fire regimes by consuming herbaceous vegetation that serves as fine fuel and, less commonly, accumulating fuel as nest material and other structures, simultaneous considerations of contrasting effects of herbivores on fire have scarcely been addressed. We proposed that a colonial rodent, vizcacha (Lagostomus maximus...

Evaluation of minerals, phytochemical compounds and antioxidant activity of Mexican, Central American, and African green leafy vegetables

USDA-ARS?s Scientific Manuscript database

The green leafy vegetables Cnidoscolus aconitifolius and Crotalaria longirostrata are native to Mexico and Central America, while Solanum scabrum and Gynandropsis gynandra are native to Africa. They are consumed in both rural and urban areas in those places as a main food, food ingredient or traditi...

Scale and plant invasions: A theory of biotic acceptance

USGS Publications Warehouse

Stohlgren, T.J.; Jarnevich, C.; Chong, G.W.; Evangelista, P.H.

2006-01-01

We examined the relationship between native and alien plant species richness, cover, and estimated biomass at multiple spatial scales. The large dataset included 70511-m2 subplots, 1443 10-m2 subplots, and 727100-m2 subplots, nested in 727 1000-m2 plots in 37 natural vegetation types in seven states in the central United States. We found that native and alien species richness (averaged across the vegetation types) increased significantly with plot area. Furthermore, the relationship between native and alien species richness became increasingly positive and significant from the plant neighbourhood scale (1-m2) to the 10-m2, 100-m2, and the 1000-m2 scale where over 80% of the vegetation types had positive slopes between native and alien species richness. Both native and alien plant species may be responding to increased resource availability and/or habitat heterogeneity with increased area. We found significant positive relationships between the coefficient of variation of native cover in 1-m2 subplots in a vegetation type (i.e. a measure of habitat heterogeneity), and both the relative cover and relative biomass of alien plant species. At the 1000-m2 scale, we did find weak negative relationships between native species richness and the cover, biomass, and relative cover of alien plant species. However, we found very strong positive relationships between alien species richness and the cover, relative cover, and relative biomass of alien species at regional scales. These results, along with many other field studies in natural ecosystems, show that the dominant genera pattern in invasion ecology at multiple spatial scales is one of "biotic acceptance" where natural ecosystems tend to accommodate the establishment and coexistence of introduced species despite the presence and abundance of native species.

One fledgling or two in the endangered Carnaby's Cockatoo (Calyptorhynchus latirostris): a strategy for survival or legacy from a bygone era?

PubMed

Saunders, Denis A; Mawson, Peter R; Dawson, Rick

2014-01-01

Of the five species of black cockatoo in the genus Calyptorhynchus, those species with red tail bands (Red-tailed Black Cockatoo and Glossy Black Cockatoo) lay clutches of only one egg and those with white or yellow tail bands (Carnaby's Cockatoo, Baudin's Cockatoo and Yellow-tailed Black Cockatoo) usually lay clutches of two. The breeding of the endangered Carnaby's Cockatoo has been studied from 1969 to 2012 at a number of localities throughout its range in south-western Australia within a region largely cleared for agriculture. When raising nestlings the species feeds on seeds of native vegetation, and there was a strong but not significant negative relationship between nesting success and percentage loss of native vegetation within 6 and 12 km of nest hollows. There was a significant negative relationship between the health of nestlings and percentage loss of native vegetation around nest hollows. While the usual clutch size is two, average clutch size tended to be lower in areas where much native vegetation has been cleared. While both eggs hatch in 77% of two-egg clutches, the species normally fledges only one young. However, the species is capable of fledging both nestlings from a breeding attempt. Sets of siblings are usually the product of older, more experienced females nesting in areas where more native vegetation has been retained. The conservation implications of these findings are discussed in the light of predicted changes to the climate of south-western Australia.

Coastal dune dynamics in response to excavated foredune notches

NASA Astrophysics Data System (ADS)

Ruessink, B. G.; Arens, S. M.; Kuipers, M.; Donker, J. J. A.

2018-04-01

Dune management along developed coasts has traditionally focussed on the suppression of the geomorphic dynamics of the foredune to improve its role in sea defence. Because a stabilized foredune acts as an almost total barrier to aeolian transport from the beach, the habitat diversity in the more landward dunes has degraded. With the overarching objective to mitigate this undesirable loss in biodiversity, dune management projects nowadays increasingly intend to restore aeolian dynamics by reconnecting the beach-dune system with notches excavated through the foredune. Here, we use repeat topographic survey data to examine the geomorphic response of a coastal dune system in the Dutch National Park Zuid-Kennemerland to five notches excavated in 2012-2013 within an 850-m stretch of the 20-m high established foredune. The notches were dug in a V-shape (viewed onshore), with a width between approximately 50 and 100 m at the top, a (cross-dune) length between 100 and 200 m, and excavation depths between 9 and 12.5 m. The 1 × 1 m digital terrain models, acquired with airborne Lidar and UAV photogrammetry, illustrate that during the 3-year survey period the notches developed into a U-shape because of wall deflation, and that up to 8-m thick and 150-m long depositional lobes formed landward of the notches. Sand budget computations showed that the sand volume of the entire study area increased by about 22,750 m3/year, which, given the 850-m width of the study area, corresponds to an aeolian input from the beach of approximately 26.5 m3/m/year. Between 2006 and 2012 all wind-blown beach sand deposited on the seaward side of the foredune; since 2013, the notches have caused 75% of the sand to be deposited landward of the foredune. This highlights that the notches are highly effective conduits for aeolian transport into the back dunes. Future monitoring is required to determine for how long the notches will stimulate aeolian dynamics and if (and when) vegetation eventually starts to regrow and enforces the degeneration of the notches.

[Effects of alien species Robinia pseudoacacia on plant community functional structure in hilly-gully region of Loess Plateau, China.

PubMed

Zhu, Duo Ju; Wen, Zhong Ming; Zhang, Jing; Tao, Yu; Zeng, Hong Wen; Tang, Yang

2018-02-01

To investigate the effects of the introduction of Robinia pseudoacacia on the functional structure of plant communities, we selected paired-plots of R. pseudoacacia communities and native plant communities across different vegetation zones, i.e., steppe zone, forest-steppe zone, forest zone in hilly-gully region of Loess Plateau, China. We measured several functional characteristics and then compared the functional structures of R. pseudoacacia and native plant communities in different vegetation zones. The results showed that the variation of the functional traits across different vegetation zones were consistent in R. pseudoacacia community and native plant community, including leaf carbon concentration, leaf nitrogen concentration, leaf phosphorus concentration, specific leaf area, and leaf tissue density. The leaf carbon concentration, leaf nitrogen concentration, and specific leaf area of the R. pseudoacacia community were significantly higher than those of the native plant community. The trend of change that the functional diversity indices, i.e., FR ic , FE ve , FD iv , FD is , Rao of the R. pseudoacacia community and the native plant community with vegetation zones were different. The introduction of R. pseudoacacia enhanced the plant community functional diversity in the forest zone but reduced community functional diversity in the steppe zone.

The introduced tree Prosopis juliflora is a serious threat to native species of the Brazilian Caatinga vegetation.

PubMed

de Souza Nascimento, Clóvis Eduardo; Tabarelli, Marcelo; da Silva, Carlos Alberto Domingues; Leal, Inara Roberta; de Souza Tavares, Wagner; Serrão, José Eduardo; Zanuncio, José Cola

2014-05-15

Despite its economic importance in the rural context, the Prosopis juliflora tree species has already invaded millions of hectares globally (particularly rangelands), threatening native biodiversity and rural sustainability. Here we examine seedling growth (leaf area, stem diameter, plant height) and seedling mortality across five native plant species of the Caatinga vegetation in response to competition with P. juliflora. Two sowing treatments with 10 replications were adopted within a factorial 2 × 5 randomized block design. Treatments consisted of P. juliflora seeds sowed with seeds of Caesalpinia ferrea, Caesalpinia microphylla, Erythrina velutina, Mimosa bimucronata and Mimosa tenuiflora (one single native species per treatment), while seeds of native species sowed without P. juliflora were adopted as controls. Overall, our results suggest that P. juliflora can reduce seedling growth by half and cause increased seedling mortality among woody plant species. Moreover, native species exhibit different levels of susceptibility to competition with P. juliflora, particularly in terms of plant growth. Such a superior competitive ability apparently permits P. juliflora to establish monospecific stands of adult trees, locally displacing native species or limiting their recruitment. The use of less sensitive species, such as C. ferrea and M. tenuiflora, to restore native vegetation before intensive colonization by P. juliflora should be investigated as an effective approach for avoiding its continuous spread across the Caatinga region. Copyright © 2014 Elsevier B.V. All rights reserved.

The Contribution of DNA Metabarcoding to Fungal Conservation: Diversity Assessment, Habitat Partitioning and Mapping Red-Listed Fungi in Protected Coastal Salix repens Communities in the Netherlands

PubMed Central

Geml, József; Gravendeel, Barbara; van der Gaag, Kristiaan J.; Neilen, Manon; Lammers, Youri; Raes, Niels; Semenova, Tatiana A.; de Knijff, Peter; Noordeloos, Machiel E.

2014-01-01

Western European coastal sand dunes are highly important for nature conservation. Communities of the creeping willow (Salix repens) represent one of the most characteristic and diverse vegetation types in the dunes. We report here the results of the first kingdom-wide fungal diversity assessment in S. repens coastal dune vegetation. We carried out massively parallel pyrosequencing of ITS rDNA from soil samples taken at ten sites in an extended area of joined nature reserves located along the North Sea coast of the Netherlands, representing habitats with varying soil pH and moisture levels. Fungal communities in Salix repens beds are highly diverse and we detected 1211 non-singleton fungal 97% sequence similarity OTUs after analyzing 688,434 ITS2 rDNA sequences. Our comparison along a north-south transect indicated strong correlation between soil pH and fungal community composition. The total fungal richness and the number OTUs of most fungal taxonomic groups negatively correlated with higher soil pH, with some exceptions. With regard to ecological groups, dark-septate endophytic fungi were more diverse in acidic soils, ectomycorrhizal fungi were represented by more OTUs in calcareous sites, while detected arbuscular mycorrhizal genera fungi showed opposing trends regarding pH. Furthermore, we detected numerous red listed species in our samples often from previously unknown locations, indicating that some of the fungal species currently considered rare may be more abundant in Dutch S. repens communities than previously thought. PMID:24937200

78 FR 64327 - Endangered and Threatened Wildlife and Plants; Designation of Critical Habitat for the Bi-State...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-10-28

... 2001 (Pub. L. 106-554; H.R. 5658)), and our associated Information Quality Guidelines, provide criteria..., agricultural lands, and steppe dominated by native grasses and forbs. However, the Bi-State DPS of greater sage... sagebrush vegetation as well as a vegetative understory composed of native grasses and forbs are essential...

Soil development in OSL dated sandy dune substrates under Quercus robur Forest (Netherlands)

NASA Astrophysics Data System (ADS)

van Mourik, J. M.; Nierop, Ir. K.; Verstraten, J. M.

2009-04-01

Coastal dune landscapes are very dynamic. The present distribution of vegetation and soil is the result of over 2000 years of natural processes and human management. The initial soil development was controlled by an increase of the organic matter content, which consisted mainly of decomposed roots of grasses (rhizomull), and a decrease of the soil pH to 3-4 by decalcification. This stage was followed by the development of a deciduous forest, which was dominated by Quercus robur. Since 1600 AD, a large part of the deciduous forest that dominated the east side of the coastal dune landscape transferred in expensive residential areas and urbanizations. Nevertheless some parts of the oak forest belt remained. The present forest soils are acid and the controlling soil processes are leaching of sesquioxides and storage of organic matter in mormoder humus forms. The sustainability of ecosystems is closely related to the quality of the humus form, controlling nutrient cycling and water supply. Therefore, improve of knowledge of humus form development and properties is important. We applied soil micromorphology and pyrolysis-gas chromatography/mass spectrometry (GC/MS) to investigate more details of humus form development at two locations (Duivendrift and Hoek van Klaas) in the coastal dune area of the Amsterdamse Waterleidingduinen (near Haarlem, the Netherlands). However, to understand forest soil development, including the organic matter composition in the humus form, the age of the substrate and the forest is required. Therefore, we used tradition techniques as pollen analysis and radiocarbon dating but also the recently introduced optical stimulated luminescence (OSL) dating technique. OSL dating works excellent for aeolian sandy deposits with a high percentage of quartz grains. The OSL age is defined as the time after the last bleaching by solar radiation of mineral grains. Or in other words, the start of a stable period without sand drifting. In the Ah horizons we observed palynological traces of a former dune landscape with grasses and typical dune land shrubs. The F and H horizons were dominated by Quercus pollen. In thin sections we found that in the upper part of the F horizons the soil skeleton was formed by leaf litter fragments that were fragmented and decomposed by fungi and micro arthropods. The soil skeleton of the lower part of the F horizons consisted of a mixture of leaf litter fragments and (dead) root fragments. In this part of the profile, fungi and micro arthropods were also responsible for the physical and chemical organic matter decomposition. The soil skeleton of the Ah horizons was formed by mineral grains in which small sized organic aggregates occurred. These aggregates may have four possible sources: (1) sinsedimentary aggregates, involved in sand drifting, (2) fecal relicts from decomposed (older) roots of a former dune land vegetation, (2) fecal relicts from decomposed (younger) roots of the forest and its understory, and (3) infiltrated parts of fecal pallets from the overlying F horizons. The calibrated radiocarbon dates of organic matter from the upper 5 cm of the Ah horizons go back to around 1960 AD. This points to a 45 year period for the development of the ectorganic horizons, assuming that fresh organic matter did not ‘contaminate' the radiocarbon dating. The OSL the ages of quartz grains from the upper 5 cm of the Ah horizons indicate landscape stabilization around 1800AD implying that two centuries were available for vegetation and soil development. There seems to be a significant difference between the OSL and 14C ages of the top of the Ah horizon. The OSL dates are very reliable. They indicate the correct time of the transformation of drift sand into stable, vegetated landscape. The pollen spectra of the Ah horizon show traces of dune grass and shrub landscape, but probably these pollen grains originate from sinsedimentary organic aggregates. And during the juvenile phase of a quercus forest, the quercus pollen production is very low and other wind pollinated grains from dune grasses and shrubs can dominate the pollen spectra. Based upon OSL dates, a period of 200 year forest soil development is more reliable than the 14C based 45 year. We must reject the 14C ages, due to complexity of sources of soil organic matter in the Ah horizon The organic matter as investigated by analytical pyrolysis and thermally assisted hydrolysis and methylation and subsequent analysis by GC/MS revealed a major oak-derived picture. The L+F1 horizons reflected relatively undecomposed organic matter mainly derived from leaves. By contrast, in both F2+H and the Ah horizons leaf material was accompanied by root-derived components, particularly suberin. The latter may originate from barks as well, but in the Ah horizons the contribution of roots was most probably much greater. Apart from a common transformation pattern (decrease of polysaccharides, degradation of lignin and accumulation of lipids), a very small contribution of C26 alkanol indicated a chemical fingerprint of the previous grass vegetation. In conclusion: chemical analysis confirmed the soil micromorphological data, and the application of OSL dating improves our knowledge about geochronology of the system.

A 45-year time series of Saharan dune mobility from remote sensing

NASA Astrophysics Data System (ADS)

Vermeesch, P.

2012-04-01

Decadal trends in the aeolian dust record of the Sahara affect the global climate system and the nutrient budget of the Atlantic Ocean. One proposed cause of these trends are changes in the frequency and intensity of dust storms, which have hitherto been hard to quantify. Because sand flux scales with the cube of wind speed, dune migration rates can be used as a proxy for storminess. Relative changes in the storminess of the Sahara can thus be monitored by tracking the migration rates of individual sand dunes over time. The Bodélé Depression of northern Chad was selected as a target area for this method, because it is the most important point-source of aeolian dust on the planet and features the largest and fastest dunes on Earth. A collection of co-registered Landsat, SPOT, and ASTER scenes, combined with declassified American spy satellite images was used to construct a 45 year record of dune migration in the Bodélé Depression. One unexpected outcome of the study was the observation of binary dune interactions in the imagery sequence, which reveals that when two barchan dunes collide, a transfer of mass occurs so that one dune appears to travel through the other unscathed, like a solitary wave. This confirms a controversial numerical model prediction and settles a decade-old debate in aeolian geomorphology. The COSI-Corr change detection method was used to measure the dune migration rates from 1984 until 1987, 1990, 1996, 2000, 2003, 2005, 2007, 2008, 2009, and 2010. An algorithm was developed to automatically warp the resulting displacement fields back to a common point in time. Thus, individual image pixels of a dune field were tracked over time, allowing the extraction of a time series from the co-registered satellite images without further human intervention. The automated analysis was extended further back into the past by comparison of the 1984 image with declassified American spy satellite (Corona) images from 1965 and 1970. Due to the presence of specks of dust as well as image distortions caused by shrinking of the photographic film, it was not possible to automatically measure the dune displacements of these scenes with COSI-Corr. Instead, the image was georeferenced and coregistered to the 1984 Landsat imagery by third order polynomial fits to 531 tie points, and the displacements of ten large barchan dunes were measured by hand. Thanks to the 19-year time lapse between the two images used for these 'analog' measurements, their precision is better than 5%, which is comparable with that of the automated COSI-Corr analysis. The resulting dune celerities are identical to the automated measurements, which themselves show little or no temporal variability over the subsequent 26 years. The lack of any trend in the time series of dune celerity paints a picture of remarkably stable dune mobility over the past 45 years. None of the distributions fall outside the overall average of 25m/yr. The constant dune migration rates resulting from our study indicate that there has been no change in the storminess of the Sahara over the past 45 years. The observed dust trends are therefore caused by changes in vegetation cover, which in turn reflect changes in precipitation and land usage. This work highlights the importance of the hyper-arid Bodélé Depression, which provides a steady but finite supply of aeolian dust to the atmosphere without which nutrient fluxes and terrestrial albedo would be more variable than they are today.

Plant communities of Santa Rosa Island, Channel Islands National Park

USGS Publications Warehouse

Clark, Ronilee A.; Halvorson, William L.; Sawdo, Andell A.; Danielsen, Karen C.

1990-01-01

A survey of the plant communities on Santa Rosa Island, Channel Islands National Park, was conducted from January through July 1988.  Vegetation data were collected at 296 sites using a releve technique.  The plant communities described include: grassland, coastal marsh, caliche scrub, coastal sage scrub, lupine scrub, baccharis scrub, coastal bluff scrub, coastal dune scrub, mixed chaparral, mixed woodland, torrey pine woodland, closed-cone pine woodland, island oak woodland, riparian woodland, and riparian herbaceous vegetation. The areal extent of each community was mapper on USGS 7.5' topographic maps, and digitized for GIS manipulation.

Effects of white-tailed deer and invasive plants on the herb layer of suburban forests.

PubMed

Morrison, Janet A

2017-11-01

Lack of hunting and predators and proximity to human communities make suburban forests prone to high deer abundance and non-native plant invasions. I investigated these likely drivers of community structure in the herb layers of six suburban forests in one region of New Jersey, USA. In 223 plots I assessed the herb layer response to 2.5 years with or without deer fencing and the early stage of invasion from seed additions of Microstegium vimineum , an invasive, annual grass. Non-native plants and herbaceous native plants were affected very little by fencing or M. vimineum invasion. In contrast, across all forests the combination of deer access and M. vimineum addition had a strongly negative effect on woody native percent cover. Forests differed in overall fencing effects on woody natives; their cover was greater in fenced plots in just three forests, suggesting greater deer pressure in those forests during the experiment. The early invasion by M. vimineum was greatest in two of these same forests, but was not influenced by fencing. Multi-group structural equation modelling compared two groups of forests that differed in vegetation abundance and other characteristics. It paralleled the results above and also showed no negative influence of non-native cover on native cover, even in the forests where non-native cover was greater. It identified a positive effect of light level on herb layer plants in the forests with less vegetation, and also revealed a positive effect of soil water potential (SWP) on non-native plants in the forests with more vegetation, which had higher SWP. These suburban forests within a common region varied widely in native and non-native herb layer abundance, the early success of M. vimineum invasion and the herb layer's response to early invasion and protection from deer.

Impact of native plants on bird and butterfly biodiversity in suburban landscapes.

PubMed

Burghardt, Karin T; Tallamy, Douglas W; Gregory Shriver, W

2009-02-01

Managed landscapes in which non-native ornamental plants are favored over native vegetation now dominate the United States, particularly east of the Mississippi River. We measured how landscaping with native plants affects the avian and lepidopteran communities on 6 pairs of suburban properties in southeastern Pennsylvania. One property in each pair was landscaped entirely with native plants and the other exhibited a more conventional suburban mixture of plants--a native canopy with non-native groundcover and shrubs. Vegetation sampling confirmed that total plant cover and plant diversity did not differ between treatments, but non-native plant cover was greater on the conventional sites and native plant cover was greater on the native sites. Several avian (abundance, species richness, biomass, and breeding-bird abundance) and larval lepidopteran (abundance and species richness) community parameters were measured from June 2006 to August 2006. Native properties supported significantly more caterpillars and caterpillar species and significantly greater bird abundance, diversity, species richness, biomass, and breeding pairs of native species. Of particular importance is that bird species of regional conservation concern were 8 times more abundant and significantly more diverse on native properties. In our study area, native landscaping positively influenced the avian and lepidopteran carrying capacity of suburbia and provided a mechanism for reducing biodiversity losses in human-dominated landscapes.

Potential for water salvage by removal of non-native woody vegetation from dryland river systems

USGS Publications Warehouse

Doody, T.M.; Nagler, P.L.; Glenn, E.P.; Moore, G.W.; Morino, K.; Hultine, K.R.; Benyon, R.G.

2011-01-01

Globally, expansion of non-native woody vegetation across floodplains has raised concern of increased evapotranspiration (ET) water loss with consequent reduced river flows and groundwater supplies. Water salvage programs, established to meet water supply demands by removing introduced species, show little documented evidence of program effectiveness. We use two case studies in the USA and Australia to illustrate factors that contribute to water salvage feasibility for a given ecological setting. In the USA, saltcedar (Tamarix spp.) has become widespread on western rivers, with water salvage programs attempted over a 50-year period. Some studies document riparian transpiration or ET reduction after saltcedar removal, but detectable increases in river base flow are not conclusively shown. Furthermore, measurements of riparian vegetation ET in natural settings show saltcedar ET overlaps the range measured for native riparian species, thereby constraining the possibility of water salvage by replacing saltcedar with native vegetation. In Australia, introduced willows (Salix spp.) have become widespread in riparian systems in the Murray-Darling Basin. Although large-scale removal projects have been undertaken, no attempts have been made to quantify increases in base flows. Recent studies of ET indicate that willows growing in permanently inundated stream beds have high transpiration rates, indicating water savings could be achieved from removal. In contrast, native Eucalyptus trees and willows growing on stream banks show similar ET rates with no net water salvage from replacing willows with native trees. We conclude that water salvage feasibility is highly dependent on the ecohydrological setting in which the non-native trees occur. We provide an overview of conditions favorable to water salvage. Copyright ?? 2011 John Wiley & Sons, Ltd.

Does habitat fragmentation influence nest predation in the shortgrass prairie?

USGS Publications Warehouse

Howard, M.N.; Skagen, S.K.; Kennedy, P.L.

2001-01-01

We examined the effects of habitat fragmentation and vegetation structure of shortgrass prairie and Conservation Reserve Program (CRP) lands on predation rates of artificial and natural nests in northeastern Colorado. The CRP provides federal payments to landowners to take highly erodible cropland out of agricultural production. In our study area, CRP lands have been reseeded primarily with non-native grasses, and this vegetation is taller than native shortgrass prairie. We measured three indices of habitat fragmentation (patch size, degree of matrix fragmentation, and distance from edge), none of which influenced mortality rates of artificial or natural nests. Vegetation structure did influence predation rates of artificial nests; daily mortality decreased significantly with increasing vegetation height. Vegetation structure did not influence predation rates of natural nests. CRP lands and shortgrass sites did not differ with respect to mortality rates of artificial nests. Our study area is only moderately fragmented; 62% of the study area is occupied by native grassland. We conclude that the extent of habitat fragmentation in our study area does not result in increased predation in remaining patches of shortgrass prairie habitat.

Effects of native perennial vegetation buffer strips on dissolved organic carbon in surface runoff from an agricultural landscape

Treesearch

Tomorra E. Smith; Randall K. Kolka; Xiaobo Zhou; Matthew J. Helmers; Richard M. Cruse; Mark D. Tomer

2014-01-01

Dissolved organic carbon (DOC) constitutes a small yet important part of a watershed's carbon budget because it is mobile and biologically active. Agricultural conservation practices such as native perennial vegetation (NPV) strips will influence carbon cycling of an upland agroecosystem, and could affect how much DOC enters streams in runoff, potentially...

Arthropods of native and exotic vegetation and their association with willow flycatchers and Wilson's warblers

Treesearch

Linda S. DeLay; Deborah M. Finch; Sandra Brantley; Richard Fagerlund; Michael D. Means; Jeffrey F. Kelly

1999-01-01

We compared abundance of migrating Willow Flycatchers and Wilson's Warblers to the abundance of arthropods in exotic and native vegetation at Bosque del Apache National Wildlife Refuge. We trapped arthropods using glue-boards in 1996 and 1997 in the same cottonwood, saltcedar, and willow habitats where we mist-netted birds during spring and fall migration. There...

Changes in habitat use and distribution of mouflon in the Kahuku Unit of Hawai‘i Volcanoes National Park

USGS Publications Warehouse

Palupe, Bronson; Leopold, Christina R.; Hess, Steven C.; Faford, Jonathan K.; Pacheco, Dexter; Judge, Seth W.

2016-01-01

European mouflon sheep (Ovis gmelini musimon) were introduced to Kahuku Ranch on Hawai‘i Island in 1968 and 1974 for trophy hunting and have been detrimental to the native ecosystem by trampling, bark stripping, and browsing vegetation. In 2003, Hawai‘i Volcanoes National Park acquired Kahuku Ranch and managers began removing mouflon. The objective of this project was to determine whether hunting has changed the distribution of mouflon in Kahuku, to better understand mouflon behaviour and to expedite eradication efforts. Locations from hunting and GPS telemetry data during 2007–14 were used to determine the effect of hunting on mouflon distribution by examining distance to roads and habitat use. Mouflon seemed to avoid roads after hunting pressure increased and their distribution within vegetation types changed over time. Mouflon without hunting pressure were detected in native shrub habitat in 68% of all observations. Hunted mouflon were encountered less in native shrub habitat and more in other habitats including open forest, closed forest, and areas with no vegetation. These changes suggest that hunting has influenced the distribution of mouflon over time away from native shrub and into other vegetation types where they may be more difficult to control.

Native plants for roadside revegetation : field evaluations and best practices identification.

DOT National Transportation Integrated Search

2014-02-01

Establishing native vegetation communities on roadsides can be a proactive approach to sustainable roadways. Revegetation : with native species is the preferred management practice on Idaho roadways. : The environmental and economic benefits of : inc...

Humboldt Bay Wetlands Review and Baylands Analysis. Volume III. Habitat Classification and Mapping and Appendices.

DTIC Science & Technology

1980-08-01

also a mobile substrate habitat type, but not the massive dunes described previously; some vegetation is established. Most foredunes along the coastal...wvith the Fish and Wildlife Co~ordiinatioin ccnii h’ should be cdirected toe ard tin’, still Sit i~l~( ie . apliC ii n lilt Act IS 320.3ft Obovei

Recolonization after habitat restoration leads to decreased genetic variation in populations of a terrestrial orchid.

PubMed

Vandepitte, K; Gristina, A S; De Hert, K; Meekers, T; Roldán-Ruiz, I; Honnay, O

2012-09-01

Colonization is crucial to habitat restoration projects that rely on the spontaneous regeneration of the original vegetation. However, as a previously declining plant species spreads again, the likelihood of founder effects increases through recurrent population founding and associated serial bottlenecks. We related Amplified Fragment Length Polymorphism markers genetic variation and fitness to colonization history for all extant populations of the outcrossing terrestrial orchid Dactylorhiza incarnata in an isolated coastal dune complex. Around 1970, D. incarnata suffered a severe bottleneck yet ultimately persisted and gradually spread throughout the spatially segregated dune slacks, aided by the restoration of an open vegetation. Genetic assignment demonstrated dispersal to vacant sites from few nearby extant populations and very limited inflow from outside the spatially isolated reserve. Results further indicated that recurrent founding from few local sources resulted in the loss of genetic diversity and promoted genetic divergence (F(ST) = 0.35) among populations, but did not influence population fitness. The few source populations initially available and the limited inflow of genes from outside the study reserve, as a consequence of habitat degradation and spatial isolation, may have magnified the genetic effects of recurrent population founding. © 2012 Blackwell Publishing Ltd.

An annotated list of the mayflies, stoneflies, and caddisflies of the Sand Creek basin, Great Sand Dunes National Park and Preserve, Colorado, 2004 and 2005

USGS Publications Warehouse

Zuellig, Robert E.; Kondratieff, Boris C.; Ruiter, David E.; Thorp, Richard A.

2006-01-01

The U.S. Geological Survey, in conjunction with the Great Sand Dunes National Park and Preserve and its cooperators, did an extensive inventory of certain targeted aquatic-insect groups in the Sand Creek Basin, Great Sand Dunes National Park and Preserve, to establish a species list for future monitoring efforts. Study sites were established to monitor these groups following disturbance events. Such potential disturbances may include, but are not limited to, chemical treatment of perennial stream reaches to remove nonnative fishes and the subsequent reintroduction of native fish species, increased public use of backcountry habitat (such as hiking and fishing), and natural disturbances such as fire. This report is an annotated list of the mayflies, stoneflies, and caddisflies found in the Sand Creek Basin, Great Sand Dunes National Park and Preserve, 2004 and 2005. The primary objective of the study was to qualitatively inventory target aquatic-insect groups in perennial streams, and selected unique standing-water habitats, such as springs, and wetlands associated with the Sand Creek Basin. Efforts focused on documenting the presence of aquatic-insect species within the following taxonomic groups: Ephemeroptera (mayflies), Plecoptera (stoneflies), and Trichoptera (caddisflies). These insect orders were chosen because published species accounts, geographic distribution, and identification keys exist for many Colorado species. Given the extent of available information for these groups, there existed a potential for identifying new species and documenting range extensions of known species.

Coupled hydrogeomorphic and woody-seedling responses to controlled flood releases in a dryland river

USGS Publications Warehouse

Wilcox, Andrew C.; Shafroth, Patrick B.

2013-01-01

Interactions among flow, geomorphic processes, and riparian vegetation can strongly influence both channel form and vegetation communities. To investigate such interactions, we took advantage of a series of dam-managed flood releases that were designed in part to maintain a native riparian woodland system on a sand-bed, dryland river, the Bill Williams River, Arizona, USA. Our resulting multiyear flow experiment examined differential mortality among native and nonnative riparian seedlings, associated flood hydraulics and geomorphic changes, and the temporal evolution of feedbacks among vegetation, channel form, and hydraulics. We found that floods produced geomorphic and vegetation responses that varied with distance downstream of a dam, with scour and associated seedling mortality closer to the dam and aggradation and burial-induced mortality in a downstream reach. We also observed significantly greater mortality among nonnative tamarisk (Tamarix) seedlings than among native willow (Salix gooddingii) seedlings, reflecting the greater first-year growth of willow relative to tamarisk. When vegetation was small early in our study period, the effects of vegetation on flood hydraulics and on mediating flood-induced channel change were minimal. Vegetation growth in subsequent years resulted in stronger feedbacks, such that vegetation's stabilizing effect on bars and its drag effect on flow progressively increased, muting the geomorphic effects of a larger flood release. These observations suggest that the effectiveness of floods in producing geomorphic and ecological changes varies not only as a function of flood magnitude and duration, but also of antecedent vegetation density and size.

Remediation of blowouts by clonal plants in Maqu degraded alpine grasslands of northwest China.

PubMed

Kang, JianJun; Zhao, WenZhi; Zhao, Ming

2017-03-01

The sand-fixation of plants is considered to be the most effective and fundamental measure in desertification control in many arid and semi-arid regions. Carex brunnescens (Carex spp) and Leymus secalinus (Leymus), two perennial clonal herbs native to the Maqu degraded alpine areas of northwest China, are dominant and constructive species in active sand dunes that have excellent adaptability to fix sand dunes found to date. In order to study the ability and mechanism of sandland blowout remediation by two clone plants C. brunnescens and L. secalinus, the artificially emulated blowouts were set up in the populations of two clonal plants in the field. The results showed that both C. brunnescens and L. secalinus produced more new ramets in the artificially emulated blowouts than in the natural conditions, suggesting that the two clonal plants had strong ability in blowouts remediation; while the biomass, number of leaves and height of new ramets in the artificially emulated blowouts were less than in the natural conditions due to the restriction of poor nutrients in the artificially emulated blowouts. The ability of blowouts remediation by C. brunnescens was stronger than L. secalinus, as it generated more new ramets than L. secalinus in the process of blowouts remediation. The new ramets of L. secalinus in the blowouts remediation were mainly generated by the buds in the rhizomes which spread from outside of the blowouts; while those of C. brunnescens were generated both by the buds in the rhizomes which spread from outside, and by the buds in the rhizomes inside which were freed from dormancy in the deeper soil under wind erosion conditions. These findings suggest that through rapid clonal expansion capability, C. brunnescens and L. secalinus exhibited strong ability in blowouts remediation which can be one of the most effective strategies to restore and reconstruct degraded vegetations in Maqu alpine areas of northwest China.

M-X Environmental Technical Report. Environmental Characteristics of Alternative Designated Deployment Areas, Native Vegetation.

DTIC Science & Technology

1980-12-22

lotyabe MOunts’ns Area, evada, Wasmnn Journal of biology . Vol. 10. 02. 26 t 6 Table 3. Area in national forests in Utah - 1978. FOREST NUMBER OF ACRES...sulohee to reduce olnd a4d waner o.non . Chines tn downslop. atar spply. Plant suitable vegetation for wildlife habitat, erosion C0to.t o of .011...intrinsic value or intrinsic value or intrinsic value Native vegetation forms the basis of the food chain--all animal life, including human , is ultimately

Effects of river regulation on aeolian landscapes, Colorado River, southwestern USA

USGS Publications Warehouse

Draut, Amy E.

2012-01-01

Connectivity between fluvial and aeolian sedimentary systems plays an important role in the physical and biological environment of dryland regions. This study examines the coupling between fluvial sand deposits and aeolian dune fields in bedrock canyons of the arid to semiarid Colorado River corridor, southwestern USA. By quantifying significant differences between aeolian landscapes with and without modern fluvial sediment sources, this work demonstrates for the first time that the flow- and sediment-limiting effects of dam operations affect sedimentary processes and ecosystems in aeolian landscapes above the fluvial high water line. Dune fields decoupled from fluvial sand supply have more ground cover (biologic crust and vegetation) and less aeolian sand transport than do dune fields that remain coupled to modern fluvial sand supply. The proportion of active aeolian sand area also is substantially lower in a heavily regulated river reach (Marble–Grand Canyon, Arizona) than in a much less regulated reach with otherwise similar environmental conditions (Cataract Canyon, Utah). The interconnections shown here among river flow and sediment, aeolian sand transport, and biologic communities in aeolian dunes demonstrate a newly recognized means by which anthropogenic influence alters dryland environments. Because fluvial–aeolian coupling is common globally, it is likely that similar sediment-transport connectivity and interaction with upland ecosystems are important in other dryland regions to a greater degree than has been recognized previously.

Use of seeded exotic grasslands by wintering birds

USGS Publications Warehouse

George, Andrew D.; O'Connell, Timothy J.; Hickman, Karen R.; Leslie,, David M.

2013-01-01

Despite widespread population declines of North American grassland birds, effects of anthropogenic disturbance of wintering habitat of this guild remain poorly understood. We compared avian abundance and habitat structure in fields planted by the exotic grass Old World bluestem (Bothriochloa ischaemum; OWB) to that in native mixed-grass prairie. During winters of 2007-2008 and 2008-2009, we conducted bird and vegetation surveys in six native grass and six OWB fields in Garfield, Grant, and Alfalfa counties, Oklahoma. We recorded 24 species of wintering birds in native fields and 14 species in OWB monocultures. While vegetation structure was similar between field types, abundance of short-eared owls (Asio flammeus), northern harriers (Circus cyaneus) and Smith's longspurs (Calcarius pictus) was higher in OWB fields during at least one year. The use of OWB fields by multiple species occupying different trophic positions suggested that vegetation structure of OWB can meet habitat requirements of some wintering birds, but there is insufficient evidence to determine if it provides superior conditions to native grasses.

Assessing the potential to restore historic grazing ecosystems with tortoise ecological replacements.

PubMed

Griffiths, Christine J; Zuël, Nicolas; Jones, Carl G; Ahamud, Zairabee; Harris, Stephen

2013-08-01

The extinction of large herbivores, often keystone species, can dramatically modify plant communities and impose key biotic thresholds that may prevent an ecosystem returning to its previous state and threaten native biodiversity. A potentially innovative, yet controversial, landscape-based long-term restoration approach is to replace missing plant-herbivore interactions with non-native herbivores. Aldabran giant (Aldabrachelys gigantea) and Madagascan radiated (Astrochelys radiata) tortoises, taxonomically and functionally similar to the extinct Mauritian giant tortoises (Cylindraspis spp.), were introduced to Round Island, Mauritius, in 2007 to control the non-native plants that were threatening persistence of native species. We monitored the response of the plant community to tortoise grazing for 11 months in enclosures before the tortoises were released and, compared the cost of using tortoises as weeders with the cost of using manual labor. At the end of this period, plant biomass; vegetation height and cover; and adult, seedling, flower, and seed abundance were 3-136 times greater in adjacent control plots than in the tortoise enclosures. After their release, the free-roaming tortoises grazed on most non-native plants and significantly reduced vegetation cover, height, and seed production, reflecting findings from the enclosure study. The tortoises generally did not eat native species, although they consumed those native species that increased in abundance following the eradication of mammalian herbivores. Our results suggest that introduced non-native tortoises are a more cost-effective approach to control non-native vegetation than manual weeding. Numerous long-term outcomes (e.g., change in species composition and soil seed bank) are possible following tortoise releases. Monitoring and adaptive management are needed to ensure that the replacement herbivores promote the recovery of native plants. © 2013 Society for Conservation Biology.

Establishing native warm season grasses on Eastern Kentucky strip mines

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

Barnes, T.G.; Larkin, J.L.; Arnett, M.B.

1998-12-31

The authors evaluated various methods of establishing native warm season grasses on two reclaimed Eastern Kentucky mines from 1994--1997. Most current reclamation practices incorporate the use of tall fescue (Festuca arundinacea) and other cool-season grasses/legumes that provide little wildlife habitats. The use of native warm season grasses will likely improve wildlife habitat on reclaimed strip mines. Objectives of this study were to compare the feasibility of establishing these grasses during fall, winter, or spring using a native rangeland seeder or hydroseeding; a fertilizer application at planting; or cold-moist stratification prior to hydroseeding. Vegetative cover, bare ground, species richness, and biomassmore » samples were collected at the end of each growing season. Native warm season grass plantings had higher plant species richness compared to cool-season reclamation mixtures. There was no difference in establishment of native warm season grasses as a result of fertilization or seeding technique. Winter native warm season grass plantings were failures and cold-moist stratification did not increase plant establishment during any season. As a result of a drought during 1997, both cool-season and warm season plantings were failures. Cool-season reclamation mixtures had significantly more vegetative cover and biomass compared to native warm season grass mixtures and the native warm season grass plantings did not meet vegetative cover requirements for bond release. Forbs and legumes that established well included pale purple coneflower (Echinacea pallida), lance-leaf coreopsis (Coreopsis lanceolata), round-headed lespedeza (Lespedeza capitata), partridge pea (Cassia fasiculata), black-eyed susan (Rudbeckia hirta), butterfly milkweed (Asclepias tuberosa), and bergamot (Monarda fistulosa). Results from two demonstration plots next to research plots indicate it is possible to establish native warm season grasses on Eastern Kentucky strip mines for wildlife habitat.« less

Synthesis and study of the roadside vegetation establishment process.

DOT National Transportation Integrated Search

2011-05-01

The Texas Pollutant Discharge Elimination System (TPDES), which is administered and enforced by the : Texas Commission on Environmental Quality (TCEQ), requires perennial vegetation to 70 percent of native : or adjacent background vegetation before a...

Differences in fruit and vegetable intake by race/ethnicity and by Hispanic origin and nativity among women in the Special Supplemental Nutrition Program for Women, Infants, and Children, 2015

USDA-ARS?s Scientific Manuscript database

The objective of this exploratory study was to determine whether fruit and vegetable consumption differed by race/ethnicity, by origin and nativity among Hispanics, and by language preference (as an indicator of acculturation) among foreign-born Hispanics. We recruited 723 women enrolled in the Spec...

Long-term Effects of Nutrient Addition and Phytoremediation on Diesel and Crude Oil Contaminated Soils in subarctic Alaska

PubMed Central

Leewis, Mary-Cathrine; Reynolds, Charles M.; Leigh, Mary Beth

2014-01-01

Phytoremediation is a potentially inexpensive method of detoxifying contaminated soils using plants and associated soil microorganisms. The remote locations and cold climate of Alaska provide unique challenges associated with phytoremediation such as finding effective plant species that can achieve successful site clean-up despite the extreme environmental conditions and with minimal site management. A long-term assessment of phytoremediation was performed which capitalized on a study established in Fairbanks in 1995. The original study sought to determine how the introduction of plants (Festuca rubra, Lolium multiflorum), nutrients (fertilizer), or their combination would affect degradation of petroleum hydrocarbon (TPH) contaminated soils (crude oil or diesel) over time. Within the year following initial treatments, the plots subjected to both planting and/or fertilization showed greater overall decreases in TPH concentrations in both the diesel and crude oil contaminated soils relative to untreated plots. We re-examined this field site after 15 years with no active site management to assess the long-term effects of phytoremediation on colonization by native and non-native plants, their rhizosphere microbial communities and on petroleum removal from soil. Native and non-native vegetation had extensively colonized the site, with more abundant vegetation found on the diesel contaminated soils than the more nutrient-poor, more coarse, and acidic crude oil contaminated soils. TPH concentrations achieved regulatory clean up levels in all treatment groups, with lower TPH concentrations correlating with higher amounts of woody vegetation (trees & shrubs). In addition, original treatment type has affected vegetation recruitment to each plot with woody vegetation and more native plants in unfertilized plots. Bacterial community structure also varies according to the originally applied treatments. This study suggests that initial treatment with native tree species in combination with grasses could be an effective means for phytoremediating petroleum contaminated soils and promoting ecological recovery in cold regions. PMID:24501438

Vegetation recovery in an oil-impacted and burned Phragmites australis tidal freshwater marsh.

PubMed

Zengel, Scott; Weaver, Jennifer; Wilder, Susan L; Dauzat, Jeff; Sanfilippo, Chris; Miles, Martin S; Jellison, Kyle; Doelling, Paige; Davis, Adam; Fortier, Barret K; Harris, James; Panaccione, James; Wall, Steven; Nixon, Zachary

2018-01-15

In-situ burning of oiled marshes is a cleanup method that can be more effective and less damaging than intrusive manual and mechanical methods. In-situ burning of oil spills has been examined for several coastal marsh types; however, few published data are available for Phragmites australis marshes. Following an estimated 4200gallon crude oil spill and in-situ burn in a Phragmites tidal freshwater marsh at Delta National Wildlife Refuge (Mississippi River Delta, Louisiana), we examined vegetation impacts and recovery across 3years. Oil concentrations in marsh soils were initially elevated in the oiled-and-burned sites, but were below background levels within three months. Oiling and burning drastically affected the marsh vegetation; the formerly dominant Phragmites, a non-native variety in our study sites, had not fully recovered by the end of our study. However, overall vegetation recovery was rapid and local habitat quality in terms of native plants, particularly Sagittaria species, and wildlife value was enhanced by burning. In-situ burning appears to be a viable response option to consider for future spills in marshes with similar plant species composition, hydrogeomorphic settings, and oiling conditions. In addition, likely Phragmites stress from high water levels and/or non-native scale insect damage was also observed during our study and has recently been reported as causing widespread declines or loss of Phragmites stands in the Delta region. It remains an open question if these stressors could lead to a shift to more native vegetation, similar to what we observed following the oil spill and burn. Increased dominance by native plants may be desirable as local patches, but widespread loss of Phragmites, even if replaced by native species, could further acerbate coastal erosion and wetland loss, a major concern in the region. Copyright © 2017 Elsevier B.V. All rights reserved.

Immunotoxicological and neurotoxicological profile of health effects following subacute exposure to geogenic dust from sand dunes at the Nellis Dunes Recreation Area, Las Vegas, NV

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

Keil, Deborah, E-mail: Deborah.Keil@montana.edu; Buck, Brenda; Goossens, Dirk

Exposure to geogenic particulate matter (PM) comprised of mineral particles has been linked to human health effects. However, very little data exist on health effects associated with geogenic dust exposure in natural settings. Therefore, we characterized particulate matter size, metal chemistry, and health effects of dust collected from the Nellis Dunes Recreation Area (NDRA), a popular off-road vehicle area located near Las Vegas, NV. Adult female B6C3F1 mice were exposed to several concentrations of mineral dust collected from active and vegetated sand dunes in NDRA. Dust samples (median diameter: 4.4 μm) were suspended in phosphate-buffered saline and delivered at concentrationsmore » ranging from 0.01 to 100 mg dust/kg body weight by oropharyngeal aspiration. ICP-MS analyses of total dissolution of the dust resulted in aluminum (55,090 μg/g), vanadium (70 μg/g), chromium (33 μg/g), manganese (511 μg/g), iron (21,600 μg/g), cobalt (9.4 μg/g), copper (69 μg/g), zinc (79 μg/g), arsenic (62 μg/g), strontium (620 μg/g), cesium (13 μg/g), lead 25 μg/g) and uranium (4.7 μg/g). Arsenic was present only as As(V). Mice received four exposures, once/week over 28-days to mimic a month of weekend exposures. Descriptive and functional assays to assess immunotoxicity and neurotoxicity were performed 24 h after the final exposure. The primary observation was that 0.1 to 100 mg/kg of this sand dune derived dust dose-responsively reduced antigen-specific IgM antibody responses, suggesting that dust from this area of NDRA may present a potential health risk. - Graphical abstract: During periods of heavy wind erosion, dense dust clouds of locally emitted geogenic dust enrobe the central Nellis Dune Recreation Area dunes. - Highlights: • Toxicological effects were characterized specific to geogenic dust exposure from a recreational sand dune site in Nevada. • The geogenic dust is a mixture of many metals and crystalline silica. • Exposure to geogenic dust dose-responsively decreased IgM antibody responses in a mouse model.« less

Vegetation cover and relationships of habitat-type with elevation on the Mississippi-Alabama Barrier Islands in the initial six years after Hurricane Katrina

NASA Astrophysics Data System (ADS)

Funderburk, W.; Carter, G. A.; Anderson, C. P.; Jeter, G. W., Jr.; Otvos, E. G.; Lucas, K. L.; Hopper, N. L.

2015-12-01

Quantifying change in vegetation and geomorphic features which occur during and after storm impact is necessary toward understanding barrier island habitat resiliency under continued climate warming and sea level rise. In August, 2005, the Mississippi-Alabama barrier islands, including, from west-to-east, Cat, West Ship, East Ship, Horn, Petit Bois and Dauphin islands, were completely inundated by the tidal surge of Hurricane Katrina. Overwash, scouring, burial under sand, and mechanical damage combined with saltwater flooding and post-storm drought resulted in immediate and long-term vegetation loss. Remotely-sensed data acquired before (2004-2005) and after (2005-2011) Katrina were compared via image classification to determine immediate storm impacts and assess natural re-growth of land area and vegetation. By 2008, merely three years after the storm, total land area of Cat, West Ship, East Ship, Horn, Petit Bois and West Dauphin had recovered to 92, 90, 33, 99, 93 and 91 percent, and total vegetated land area to 85, 101, 85, 94, 83 and 102 percent of pre-Katrina values, respectively. Habitat-type maps developed from field survey, SPOT-5 and radar data were compared with LIDAR-derived elevation models to assess 2010 habitat-type distribution with respect to ground elevation. Although median MSL elevations associated with habitat classes ranged only from 0.5 m to 1.4 m, habitat-type changed distinctively with decimeter-scale changes in elevation. Low marsh, high marsh, estuarine shrubland, slash pine woodland, beach dune, bare sand and beach dune herbland were associated with median elevations of 0.5, 0.9, 1.0, 1.1, 1.2, 1.3 and 1.4 m ± 0.1 m, respectively. The anticipated increases in sea level and tropical storm energy under a continually warming climate will likely inhibit the reformation of higher-elevation habitat-types, such as shrublands and woodlands, in the 21st century.

Seedling establishment in a dynamic sedimentary environment: a conceptual framework using mangroves

PubMed Central

Balke, Thorsten; Webb, Edward L; van den Elzen, Eva; Galli, Demis; Herman, Peter M J; Bouma, Tjeerd J

2013-01-01

1. Vegetated biogeomorphic systems (e.g. mangroves, salt marshes, dunes, riparian vegetation) have been intensively studied for the impact of the biota on sediment transport processes and the resulting self-organization of such landscapes. However, there is a lack of understanding of physical disturbance mechanisms that limit primary colonization in active sedimentary environments. 2. This study elucidates the effect of sediment disturbance during the seedling stage of pioneer vegetation, using mangroves as a model system. We performed mesocosm experiments that mimicked sediment disturbance as (i) accretion/burial of plants and (ii) erosion/excavation of plants of different magnitudes and temporal distribution in combination with water movement and inundation stress. 3. Cumulative sediment disturbance reduced seedling survival, with the faster-growing Avicennia alba showing less mortality than the slower-growing Sonneratia alba. The presence of the additional stressors (inundation and water movement) predominantly reduced the survival of S. alba. 4. Non-lethal accretion treatments increased shoot biomass of the seedlings, whereas non-lethal erosion treatments increased root biomass allocation. This morphological plasticity in combination with the abiotic disturbance history determined how much maximum erosion the seedlings were able to withstand. 5. Synthesis and applications. Seedling survival in dynamic sedimentary environments is determined by the frequency and magnitude of sediment accretion or erosion events, with non-lethal events causing feedbacks to seedling stability. Managers attempting restoration of mangroves, salt marshes, dunes and riparian vegetation should recognize sediment dynamics as a main bottleneck to primary colonization. The temporal distribution of erosion and accretion events has to be evaluated against the ability of the seedlings to outgrow or adjust to disturbances. Our results suggest that selecting fast-growing pioneer species and measures to enhance seedling growth or temporary reduction in sediment dynamics at the restoration site can aid restoration success for vegetated biogeomorphic ecosystems. PMID:23894211

Using Species Distribution Models to Predict Potential Landscape Restoration Effects on Puma Conservation.

PubMed

Angelieri, Cintia Camila Silva; Adams-Hosking, Christine; Ferraz, Katia Maria Paschoaletto Micchi de Barros; de Souza, Marcelo Pereira; McAlpine, Clive Alexander

2016-01-01

A mosaic of intact native and human-modified vegetation use can provide important habitat for top predators such as the puma (Puma concolor), avoiding negative effects on other species and ecological processes due to cascade trophic interactions. This study investigates the effects of restoration scenarios on the puma's habitat suitability in the most developed Brazilian region (São Paulo State). Species Distribution Models incorporating restoration scenarios were developed using the species' occurrence information to (1) map habitat suitability of pumas in São Paulo State, Southeast, Brazil; (2) test the relative contribution of environmental variables ecologically relevant to the species habitat suitability and (3) project the predicted habitat suitability to future native vegetation restoration scenarios. The Maximum Entropy algorithm was used (Test AUC of 0.84 ± 0.0228) based on seven environmental non-correlated variables and non-autocorrelated presence-only records (n = 342). The percentage of native vegetation (positive influence), elevation (positive influence) and density of roads (negative influence) were considered the most important environmental variables to the model. Model projections to restoration scenarios reflected the high positive relationship between pumas and native vegetation. These projections identified new high suitability areas for pumas (probability of presence >0.5) in highly deforested regions. High suitability areas were increased from 5.3% to 8.5% of the total State extension when the landscapes were restored for ≥ the minimum native vegetation cover rule (20%) established by the Brazilian Forest Code in private lands. This study highlights the importance of a landscape planning approach to improve the conservation outlook for pumas and other species, including not only the establishment and management of protected areas, but also the habitat restoration on private lands. Importantly, the results may inform environmental policies and land use planning in São Paulo State, Brazil.

Controls of vegetation structure and net primary production in restored grasslands

USGS Publications Warehouse

Munson, Seth M.; Lauenroth, William K.

2014-01-01

1. Vegetation structure and net primary production (NPP) are fundamental properties of ecosystems. Understanding how restoration practices following disturbance interact with environmental factors to control these properties can provide insight on how ecosystems recover and guide management efforts. 2. We assessed the relative contribution of environmental and restoration factors in controlling vegetation structure, above- and below-ground investment in production across a chronosequence of semiarid Conservation Reserve Program (CRP) fields recovering from dryland wheat cropping relative to undisturbed grassland. Importantly, we determined the role of plant diversity and how seeding either native or introduced perennial grasses influenced the recovery of vegetation properties. 3. Plant basal cover increased with field age and was highest in CRP fields seeded with native perennial grasses. In contrast, fields seeded with introduced perennial grasses had tall-growing plants with relatively low basal cover. These vegetation structural characteristics interacted with precipitation, but not soil characteristics, to influence above-ground NPP (ANPP). Fields enrolled in the CRP program for >7 years supported twice as much ANPP as undisturbed shortgrass steppe in the first wet year of the study, but all CRP fields converged on a common low amount of ANPP in the following dry year and invested less than half as much as the shortgrass steppe in below-ground biomass. 4. ANPP in CRP fields seeded with native perennial grasses for more than 7 years was positively related to species richness, whereas ANPP in CRP fields seeded with introduced perennial grasses were controlled more by dominant species. 5. Synthesis and applications. Seeding with introduced, instead of native, perennial grasses had a strong direct influence on vegetation structure, including species richness, which indirectly affected NPP through time. However, the effects of restoring either native or introduced grasses on NPP were secondary to low water availability. Therefore, restoration strategies that maximize basal cover and below-ground biomass, which promote water acquisition, may lead to high resilience in semiarid and arid regions.

Origin of the Sinai-Negev erg, Egypt and Israel: mineralogical and geochemical evidence for the importance of the Nile and sea level history

USGS Publications Warehouse

Muhs, Daniel R.; Roskin, Joel; Tsoar, Haim; Skipp, Gary; Budahn, James R.; Sneh, Amihai; Porat, Naomi; Stanley, Jean-Daniel; Katra, Itzhak; Blumberg, Dan G.

2013-01-01

The Sinai–Negev erg occupies an area of 13,000 km2 in the deserts of Egypt and Israel. Aeolian sand of this erg has been proposed to be derived from the Nile Delta, but empirical data supporting this view are lacking. An alternative source sediment is sand from the large Wadi El Arish drainage system in central and northern Sinai. Mineralogy of the Negev and Sinai dunes shows that they are high in quartz, with much smaller amounts of K-feldspar and plagioclase. Both Nile Delta sands and Sinai wadi sands, upstream of the dunes, also have high amounts of quartz relative to K-feldspar and plagioclase. However, Sinai wadi sands have abundant calcite, whereas Nile Delta sands have little or no calcite. Overall, the mineralogical data suggest that the dunes are derived dominantly from the Nile Delta, with Sinai wadi sands being a minor contributor. Geochemical data that proxy for both the light mineral fraction (SiO2/10–Al2O3 + Na2O + K2O–CaO) and heavy mineral fraction (Fe2O3–MgO–TiO2) also indicate a dominant Nile Delta source for the dunes. Thus, we report here the first empirical evidence that the Sinai–Negev dunes are derived dominantly from the Nile Delta. Linkage of the Sinai–Negev erg to the Nile Delta as a source is consistent with the distribution of OSL ages of Negev dunes in recent studies. Stratigraphic studies show that during the Last Glacial period, when dune incursions in the Sinai–Negev erg began, what is now the Nile Delta area was characterized by a broad, sandy, minimally vegetated plain, with seasonally dry anastomosing channels. Such conditions were ideal for providing a ready source of sand for aeolian transport under what were probably much stronger glacial-age winds. With the post-glacial rise in sea level, the Nile River began to aggrade. Post-glacial sedimentation has been dominated by fine-grained silts and clays. Thus, sea level, along with favorable climatic conditions, emerges as a major influence on the timing of dune activity in the Sinai–Negev erg, through its control on the supply of sand from the Nile Delta. The mineralogy of the Sinai–Negev dunes is also consistent with a proposed hypothesis that these sediments are an important source of loess in Israel.

Shifts in vegetation affect organic carbon quality in a coastal marsh along the Hudson River Estuary

NASA Astrophysics Data System (ADS)

Zhang, A. H.; Corbett, J. E.; Tfaily, M. M.; Martin, I.; Ho, L.; Sun, E.; Sevilla, L.; Vincent, S.; Newton, R.; Peteet, D. M.

2015-12-01

To better understand carbon storage in coastal salt marshes, samples were collected from Piermont Marsh, NY (40 ̊00' N, 73 ̊55'W) located within the Hudson River Estuary. Porewater from three different vegetation sites was analyzed to compare the quality of the dissolved organic carbon. Sites contained either native or invasive vegetation with variations in live plant root depth. Porewater was taken from 0-3m in 50cm intervals, and sites were dominated either by invasive Phragmites australis, native Eleocharis , or native mixed vegetation (Spartina patens, Scirpus, and Typha angustifolia). Sites dominated by invasive Phragmites australis were found to have lower dissolved organic carbon (DOC) concentrations, lower cDOM absorption values, and more labile organic carbon compounds. The molecular composition of the DOC was determined with Fourier Transform Ion Cyclotron Mass Spectrometry (FT-ICR-MS). Labile DOC components were defined as proteins, carbohydrates, and amino sugars while recalcitrant DOC components were defined as lipids, unsaturated hydrocarbons, lignins, tannins, and condensed hydrocarbons. For the Phragmites, Eleocharis, and mixed vegetation sites, average DOC concentrations with depth were found to be 1.71 ± 1.06, 4.64 ± 1.73, and 4.62 ± 3.5 (mM), respectively and cDOM absorption values with depth were found to be 13.22 ± 4.81, 49.42 ± 10.8, and 35.74 ± 17.49 (m-1). Additionally, DOC concentrations increased with depth in the mixed vegetation and Eleocharis sites, but remained relatively constant in the Phragmites site. The percent of labile compounds in the surface samples were found to be 19.02, 14.64, and 14.07% for the Phragmites, Eleocharis, and mixed vegetation sites, respectively. These findings suggest that sites dominated by Phragmites may have more reactive DOC substrates than sites dominated by native vegetation. These results indicate that the carbon storage in marshes invaded by Phragmites would be expected to decrease over time.

Geologic and paleoecologic studies of the Nebraska Sand Hills

USGS Publications Warehouse

Ahlbrandt, Thomas S.; Fryberger, S.G.; Hanley, John H.; Bradbury, J. Platt

1980-01-01

PART A: The Nebraska Sand Hills are an inactive, late Quaternary, most probably Holocene, dune field (covering 57,000 km 2 ) that have been eroded along streams and in blowouts, resulting in excellent lateral and vertical exposures of the stratification of dune and interdune sediments. This paper presents new data on the geometry, primary sedimentary structures, modification of sedimentary structures, direction of sand movement, and petrography of these eolian deposits. Eolian deposits of the Sand Hills occur as relatively thin (9-24 m) 'blanket' sands, composed of a complex of dune and discontinuous, diachronous interdune deposits unconformably overlying fluviolacustrine sediments. The internal stratification of large dunes in the Sand Hills (as high as 100 m), is similar to the internal stratification of smaller dunes of the same type in the Sand Hills, differing only in scale. Studies of laminae orientation in the Sand Hills indicate that transverse, barchan, and blowout dunes can be differentiated in rocks of eolian origin using both the mean dip angle of laminae and the mean angular deviation of dip direction. A variety of secondary structures modify or replace primary eolian stratification in the Sand Hills, the more common of which are dissipation structures and bioturbation. Dissipation structures in the Sand Hills may develop when infiltrating water deposits clay adjacent to less permeable layers in the sand, or along the upper margins of frozen layers that form in the sands during winter. Cross-bed measurements from dunes of the Nebraska Sand Hills necessitate a new interpretation of the past sand transport directions. The data from these measurements indicate a general northwest-to-southeast drift of sand, with a more southerly drift in the southeast part of the Sand Hills. A large area of small dunes < 100 m high) described by Smith (1965) as linear or seif in the central part of the Sand Hills was interpreted by him on the basis of morphology only. We interpret these as transverse-ridge dunes that were generally moving to the south. Further, our measurements indicate that dunes in the western part of the Sand Hills did not develop in response to present-day effective wind regimes. The presence of 'transverse' and en echelon barchan dunes in the Sand Hills corresponds to a developmental sequence of barchan to linear dunes proposed by Tsoar (1978). Dune and interdune deposits of the Sand Hills are subfeldsarenites to feldsarenites. Sand grains are commonly coated with montmorillonitic clay, which may be the local source of the clay concentrated in the dissipation structures. Textures of sand samples taken from adjacent layers within a dune were as dissimilar as textures of samples taken from widely separated dunes. This common occurrence indicates that textural data must be used carefully and in combination with other data to recognize ancient rocks of eolian origin. Organic material derived from a variety of flora and fauna that inhabit the interdunes (chapters B and C) generated both oil and gas upon heating. Thus, interdune sediments may be an indigenous hydrocarbon source if buried in eolianites. The twofold stratigraphy of loess and correlative dune deposits in the Sand Hills proposed by Reed and Dreeszen (1965) could not be confirmed by the present study. Rather, available data indicate that the dunes represent a single formation as suggested by Lugn (1935). PART B: Three assemblages of nonmarine Mollusca from paleointerdune deposits in the Nebraska Sand Hills inhabited shallow, quiet, vegetated, subpermanent or temporary, freshwater interdune ponds and adjacent terrestrial habitats. Analysis of factors affecting the taxonomic composition, diversity, and abundance of species in living assemblages of mollusks support this interpretation. The mollusks have long biostratigraphic ranges and broad biogeographic distributions. They fail to establish precise age relations of the faunas othe

Ganges River Delta, Bangladesh, India

NASA Image and Video Library

1994-11-14

The Ganges River Delta is the largest inter-tidal delta in the world. With its extensive mangrove mud flats, swamp vegetation and sand dunes, it is characteristic of many tropical and subtropical coasts. As seen in this photograph, the tributaries and distributaries of the Ganges and Brahmaputra Rivers deposit huge amounts of silt and clay that create a shifting maze of waterways and islands in the Bay of Bengal.

A guide to bumblebees of the Interior

USDA-ARS?s Scientific Manuscript database

Imports of pollinators are becoming problematic with high transportation and packaging costs, disease, and concerns regarding non-native species affecting native beneficial insects and habitat. Native bees, such as bumble bees, may be responsible for almost $3.07 billion of fruits and vegetables pro...

45 CFR 670.3 - Definitions.

Code of Federal Regulations, 2014 CFR

2014-10-01

... any part, product, egg, or offspring of or the dead body or parts thereof excluding fossils. Native... indigenous to Antarctica. It includes any part thereof, but excludes fossils. Native mammal means any member... fossils. Native plant means any terrestrial or freshwater vegetation, including bryophytes, lichens, fungi...

45 CFR 670.3 - Definitions.

Code of Federal Regulations, 2012 CFR

2012-10-01

... any part, product, egg, or offspring of or the dead body or parts thereof excluding fossils. Native... indigenous to Antarctica. It includes any part thereof, but excludes fossils. Native mammal means any member... fossils. Native plant means any terrestrial or freshwater vegetation, including bryophytes, lichens, fungi...

45 CFR 670.3 - Definitions.

Code of Federal Regulations, 2011 CFR

2011-10-01

... any part, product, egg, or offspring of or the dead body or parts thereof excluding fossils. Native... indigenous to Antarctica. It includes any part thereof, but excludes fossils. Native mammal means any member... fossils. Native plant means any terrestrial or freshwater vegetation, including bryophytes, lichens, fungi...

45 CFR 670.3 - Definitions.

Code of Federal Regulations, 2013 CFR

2013-10-01

... any part, product, egg, or offspring of or the dead body or parts thereof excluding fossils. Native... indigenous to Antarctica. It includes any part thereof, but excludes fossils. Native mammal means any member... fossils. Native plant means any terrestrial or freshwater vegetation, including bryophytes, lichens, fungi...

Earth Observations

NASA Image and Video Library

2011-06-02

ISS028-E-006830 (2 June 2011) --- Okavango Swamp in Botswana is featured in this image photographed by an Expedition 28 crew member on the International Space Station. This short focal-length photograph shows the entire Okavango ?delta,? a swampland known in Southern Africa as the ?Jewel of the Kalahari Desert?. This enormous pristine wetland of forest, wildlife, and freshwater almost miraculously appears in a desert where surface water is typically non-existent. The water comes from the Okavango River which rises in the high-rainfall zone of southern Angola, hundreds of kilometers to the northwest. The dark green forested floodplain is approximately 10 kilometers wide where it enters the view (left). The Okavango then enters a rift basin which allows the river to spread out, forming the wetland. The width of the rift determines the dimensions of the delta?150 kilometers from apex to the linear downstream margin (right). The apex fault is more difficult to discern, but two fault lines actually define the downstream margin; the fault traces are indicated by linear stream channels and vegetation patterns oriented at nearly right angles to the southeast-trending distributary channels at center. The distributary channels carry sediment from the Okavango River that is deposited within the rift basin. Over time, a fan-shaped morphology of the deposits has developed, leading to characterization of the wetland as the Okavango ?delta?. The drying trend from higher rainfall in the north (left) to less rainfall in central Botswana (right) is shown by the change from the greens of denser savanna vegetation to browns of an open ?thornscrub? savanna. More subtle distinctions appear: the distributary arms of the delta include tall, permanent riverine and seasonal forest (dark green), with grasses and other savanna vegetation (light green) on floodplains?which appear well watered in this image. Linear dunes, emplaced by constant winds from the east during drier climates, appear as straight lines at left. The dunes are 10 meters high and their sands hold enough moisture for some trees to grow on them. Counter-intuitively, the low ?streets? between the dunes are treeless because they are dominated by dense dry white soils known as calcretes.

The use of plant community attributes to detect habitat quality in coastal environments

PubMed Central

Del Vecchio, Silvia; Slaviero, Antonio; Fantinato, Edy; Buffa, Gabriella

2016-01-01

The monitoring of biodiversity has mainly focused on the species level. However, researchers and land managers are making increasing use of complementary assessment tools that address higher levels of biological organization, i.e. communities, habitats and ecosystems. Recently, a variety of frameworks have been proposed for assessing the conservation status of communities or ecosystems. Among the various criteria proposed, all the protocols suggest considering (i) spatial aspects (range and area), and (ii) qualitative aspects of specific structures and functions. However, changes to ecological function are difficult to quantify and many protocols end up by using qualitative criteria. The aim of this work was to test the efficacy of some plant community attributes for the detection of vegetation quality in sand dune plant communities. We chose plant community attributes that either help to distinguish a habitat from others (diagnostic components) or play a significant role in habitat function and persistence over time. We used a diachronic approach by contrasting up-to-date vegetation data with data from previous studies carried out within the same areas. Changes in species composition were detected through detrended correspondence analyses (detrended correspondence analyses), Multi-Response Permutation Procedures and Indicator Species Analysis, while structural changes were analyzed by comparing species richness, total species cover, ecological groups of species and growth forms through null models. Ecological groups such as native focal species and aliens, and growth forms proved their efficacy in discriminating between habitat types and in describing their changes over time. The approach used in this study may provide an instrument for the assessment of plant community quality that can be applied to other coastal ecosystems. PMID:27255516

Use of vegetation sampling and analysis to detect a problem within a portion of a prairie restoration project.

PubMed

Franson, Raymond; Scholes, Chad; Krabbe, Stephen

2017-01-02

In June 2005, the Department of Energy (DOE) began establishing the 60-ha Howell Prairie around the disposal cell at the DOE Weldon Spring Site (WSS). Prairies were historically present in the area of the site. Quantitative Cover sampling was used to quantify Total Cover, Native Grass Cover, Non-Native Grass Cover, Native Forb Cover, Non-Native Forb Cover, Warm Season (C 4 Grass), Cool Season (C 3 Grass), Perennial Cover and Annual Cover, Litter, and Bare Ground. Four permanent vegetation sampling plots were established. The first 4 years of vegetation measurements at Howell Prairie were made during above-average rainfall years on burned and unburned plots. The fifth-year (2012) vegetation measurements were made after below-average rainfall. Five years of results not only document the consistency of the restoration effort in three areas, but also demonstrate deficiencies in Grass Cover in a fourth area. The results are not only useful for Howell Prairie, but will be useful for restoration work throughout the region. Restoration work suffers from a lack of success monitoring and in this case from a lack of available reference areas. Floristic Quality Indices are used to make qualitative comparisons of the site to Konza Prairie sites.

An invasive plant alters phenotypic selection on the vegetative growth of a native congener.

PubMed

Beans, Carolyn M; Roach, Deborah A

2015-02-01

The ecological consequences of plant competition have frequently been tested, but the evolutionary outcomes of these interactions have gone largely unexplored. The study of species invasions can make an important contribution to this field of research by allowing us to watch ecological and evolutionary processes unfold as a novel species is integrated into a plant community. We explored the ecological and evolutionary impact of an invasive jewelweed, Impatiens glandulifera, on a closely related native congener, I. capensis and asked: (1) Does the presence of the invasive jewelweed alter the fitness of native jewelweed populations? (2) Does the invasive jewelweed affect the vegetative growth of the native congener? and (3) Does the invasive jewelweed alter phenotypic selection on the vegetative traits of the native congener? We used a greenhouse competition experiment, an invasive species removal field experiment, and a survey of natural populations. We show that when the invasive jewelweed is present, phenotypic selection favors native jewelweed individuals investing less in rapid upward growth and more in branching and fruiting potential through the production of nodes. This research demonstrates that invasive plants have the potential to greatly alter natural selection on native competitors. Studies investigating altered selection in invaded communities can reveal the potential evolutionary impact of invasive competitors, while deepening our understanding of the more general role of competition in driving plant evolution and permitting species coexistence. © 2015 Botanical Society of America, Inc.

Multi-index time series monitoring of drought and fire effects on desert grasslands

USGS Publications Warehouse

Villarreal, Miguel; Norman, Laura M.; Buckley, Steven; Wallace, Cynthia S.A.; Coe, Michelle A.

2016-01-01

The Western United States is expected to undergo both extended periods of drought and longer wildfire seasons under forecasted global climate change and it is important to understand how these disturbances will interact and affect recovery and composition of plant communities in the future. In this research paper we describe the temporal response of grassland communities to drought and fire in southern Arizona, where land managers are using repeated, prescribed fire as a habitat restoration tool. Using a 25-year atlas of fire locations, we paired sites with multiple fires to unburned control areas and compare satellite and field-based estimates of vegetation cover over time. Two hundred and fifty Landsat TM images, dating from 1985–2011, were used to derive estimates of Total Vegetation Fractional Cover (TVFC) of live and senescent grass using the Soil-Adjusted Total Vegetation Index (SATVI) and post-fire vegetation greenness using the Normalized Difference Vegetation Index (NDVI). We also implemented a Greenness to Cover Index that is the difference of time-standardized SATVI-TVFC and NDVI values at a given time and location to identify post-fire shifts in native, non-native, and annual plant cover. The results highlight anomalous greening and browning during drought periods related to amounts of annual and non-native plant cover present. Results suggest that aggressive application of prescribed fire may encourage spread of non-native perennial grasses and annual plants, particularly during droughts.

Ecosystem implications of conserving endemic versus eradicating introduced large herbivores in the Galapagos Archipelago

USGS Publications Warehouse

Bastille-Rousseau, Guillaume; Gibbs, James P.; Campbell, Karl; Yackulic, Charles B.; Blake, Stephen

2017-01-01

Restoration of damaged ecosystems through invasive species removal and native species conservation is an increasingly common practice in biodiversity conservation. Estimating the degree of ecosystem response attributable specifically to eradication of exotic herbivores versus restoration of native herbivores is often difficult and is complicated by concurrent temporal changes in other factors, especially climate. We investigated the interactive impacts of native mega-herbivores (giant tortoises) and the eradication of large alien herbivores (goats) on vegetation productivity across the Galapagos Archipelago. We examined archipelago-wide patterns of Normalized Difference Vegetation Index (NDVI) as a proxy for vegetation productivity between 2001 and 2015 and evaluated how goat and historical and current tortoise occurrence influenced productivity. We used a breakpoint analysis to detect change in trends in productivity from five targeted areas following goat eradication. We found a positive association between tortoise occurrence and vegetation productivity and a negative association with goat occurrence. We also documented an increase in plant productivity following goat removal with recovery higher in moister regions than in arid region, potentially indicating an alternate stable state has been created in the latter. Climate variation also contributed to the detected improvement in productivity following goat eradication, sometimes obscuring the effect of eradication but more usually magnifying it by up to 300%. Our work offers perspectives regarding the effectiveness and outcomes of eradicating introduced herbivores and re-introducing native herbivores, and the merits of staging them simultaneously in order to restore critical ecosystem processes such as vegetation productivity.

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

Treesearch

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

2015-01-01

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

Native and Non-Native Plants Provide Similar Refuge to Invertebrate Prey, but Less than Artificial Plants

PubMed Central

Grutters, Bart M. C.; Pollux, Bart J. A.; Verberk, Wilco C. E. P.; Bakker, Elisabeth S.

2015-01-01

Non-native species introductions are widespread and can affect ecosystem functioning by altering the structure of food webs. Invading plants often modify habitat structure, which may affect the suitability of vegetation as refuge and could thus impact predator-prey dynamics. Yet little is known about how the replacement of native by non-native vegetation affects predator-prey dynamics. We hypothesize that plant refuge provisioning depends on (1) the plant’s native status, (2) plant structural complexity and morphology, (3) predator identity, and (4) prey identity, as well as that (5) structurally similar living and artificial plants provide similar refuge. We used aquatic communities as a model system and compared the refuge provided by plants to macroinvertebrates (Daphnia pulex, Gammarus pulex and damselfly larvae) in three short-term laboratory predation experiments. Plant refuge provisioning differed between plant species, but was generally similar for native (Myriophyllum spicatum, Ceratophyllum demersum, Potamogeton perfoliatus) and non-native plants (Vallisneria spiralis, Myriophyllum heterophyllum, Cabomba caroliniana). However, plant refuge provisioning to macroinvertebrate prey depended primarily on predator (mirror carp: Cyprinus carpio carpio and dragonfly larvae: Anax imperator) and prey identity, while the effects of plant structural complexity were only minor. Contrary to living plants, artificial plant analogues did improve prey survival, particularly with increasing structural complexity and shoot density. As such, plant rigidity, which was high for artificial plants and one of the living plant species evaluated in this study (Ceratophyllum demersum), may interact with structural complexity to play a key role in refuge provisioning to specific prey (Gammarus pulex). Our results demonstrate that replacement of native by structurally similar non-native vegetation is unlikely to greatly affect predator-prey dynamics. We propose that modification of predator-prey interactions through plant invasions only occurs when invading plants radically differ in growth form, density and rigidity compared to native plants. PMID:25885967

Effects of white-tailed deer and invasive plants on the herb layer of suburban forests

PubMed Central

2017-01-01

Abstract Lack of hunting and predators and proximity to human communities make suburban forests prone to high deer abundance and non-native plant invasions. I investigated these likely drivers of community structure in the herb layers of six suburban forests in one region of New Jersey, USA. In 223 plots I assessed the herb layer response to 2.5 years with or without deer fencing and the early stage of invasion from seed additions of Microstegium vimineum, an invasive, annual grass. Non-native plants and herbaceous native plants were affected very little by fencing or M. vimineum invasion. In contrast, across all forests the combination of deer access and M. vimineum addition had a strongly negative effect on woody native percent cover. Forests differed in overall fencing effects on woody natives; their cover was greater in fenced plots in just three forests, suggesting greater deer pressure in those forests during the experiment. The early invasion by M. vimineum was greatest in two of these same forests, but was not influenced by fencing. Multi-group structural equation modelling compared two groups of forests that differed in vegetation abundance and other characteristics. It paralleled the results above and also showed no negative influence of non-native cover on native cover, even in the forests where non-native cover was greater. It identified a positive effect of light level on herb layer plants in the forests with less vegetation, and also revealed a positive effect of soil water potential (SWP) on non-native plants in the forests with more vegetation, which had higher SWP. These suburban forests within a common region varied widely in native and non-native herb layer abundance, the early success of M. vimineum invasion and the herb layer’s response to early invasion and protection from deer. PMID:29218140

Impacts of Carpobrotus edulis (L.) N.E.Br. on the Germination, Establishment and Survival of Native Plants: A Clue for Assessing Its Competitive Strength

PubMed Central

Novoa, Ana; González, Luís

2014-01-01

Does Carpobrotus edulis have an impact on native plants? How do C. edulis’ soil residual effects affect the maintenance of native populations? What is the extent of interspecific competition in its invasion process? In order to answer those questions, we established pure and mixed cultures of native species and C. edulis on soil collected from invaded and native areas of Mediterranean coastal dunes in the Iberian Peninsula. We examined the impact of the invader on the germination, growth and survival of seeds and adult plants of two native plant species (Malcolmia littorea (L.) R.Br, and Scabiosa atropurpurea L.) growing with ramets or seeds of C. edulis. Residual effects of C. edulis on soils affected the germination process and early growth of native plants in different ways, depending on plant species and density. Interspecific competition significantly reduced the germination and early growth of native plants but this result was soil, density, timing and plant species dependent. Also, at any density of adult individuals of C. edulis, established native adult plants were not competitive. Moreover, ramets of C. edulis had a lethal effect on native plants, which died in a short period of time. Even the presence of C. edulis seedlings prevents the recruitment of native species. In conclusion, C. edulis have strong negative impacts on the germination, growth and survival of the native species M. littorea and S. atropurpurea. These impacts were highly depended on the development stages of native and invasive plants. Our findings are crucial for new strategies of biodiversity conservation in coastal habitats. PMID:25210924

Impacts of Carpobrotus edulis (L.) N.E.Br. on the germination, establishment and survival of native plants: a clue for assessing its competitive strength.

PubMed

Novoa, Ana; González, Luís

2014-01-01

Does Carpobrotus edulis have an impact on native plants? How do C. edulis' soil residual effects affect the maintenance of native populations? What is the extent of interspecific competition in its invasion process? In order to answer those questions, we established pure and mixed cultures of native species and C. edulis on soil collected from invaded and native areas of Mediterranean coastal dunes in the Iberian Peninsula. We examined the impact of the invader on the germination, growth and survival of seeds and adult plants of two native plant species (Malcolmia littorea (L.) R.Br, and Scabiosa atropurpurea L.) growing with ramets or seeds of C. edulis. Residual effects of C. edulis on soils affected the germination process and early growth of native plants in different ways, depending on plant species and density. Interspecific competition significantly reduced the germination and early growth of native plants but this result was soil, density, timing and plant species dependent. Also, at any density of adult individuals of C. edulis, established native adult plants were not competitive. Moreover, ramets of C. edulis had a lethal effect on native plants, which died in a short period of time. Even the presence of C. edulis seedlings prevents the recruitment of native species. In conclusion, C. edulis have strong negative impacts on the germination, growth and survival of the native species M. littorea and S. atropurpurea. These impacts were highly depended on the development stages of native and invasive plants. Our findings are crucial for new strategies of biodiversity conservation in coastal habitats.

Adventitious root production and plastic resource allocation to biomass determine burial tolerance in woody plants from central Canadian coastal dunes.

PubMed

Dech, Jeffery P; Maun, M Anwar

2006-11-01

Burial is a recurrent stress imposed upon plants of coastal dunes. Woody plants are buried on open coastal dunes and in forested areas behind active blowouts; however, little is known about the burial responses and adaptive traits of these species. The objectives of this study were: (a) to determine the growth and morphological responses to burial in sand of seven woody plant species native to central Canadian coastal dunes; and (b) to identify traits that determine burial tolerance in these species. Field experiments were conducted to determine the responses of each species to burial. Saplings were exposed to burial treatments of 0, 10, 25, 50 and 75 % of their height. Burial responses were evaluated based on regressions of total biomass, height, adventitious root production and percentage allocation to shoot, root and adventitious root biomass on percentage burial. Pinus strobus and Picea glauca lacked burial tolerance. In response to the burial gradient, these species showed a strong linear decline in total biomass, minimal adventitious root production that peaked at moderate levels (25-50 % burial) and no change in allocation to shoots vs. roots. The tolerant species Juniperus virginiana, Thuja occidentalis and Picea mariana showed a quadratic response to burial, with little change in biomass up to 50 % burial, but a large decline at 75 %. These species produced abundant adventitious roots up to 50 % burial, but did not alter allocation patterns over the range of burial levels. Populus balsamifera and Salix cordata were stimulated by burial. These species showed linear increases in biomass with increasing burial, produced copious adventitious roots across the gradient and showed a clear shift in allocation to vertical shoot growth and adventitious root production at the expense of the original roots under high burial conditions. Adventitious root production and plastic resource allocation to biomass are adaptive traits of coastal dune woody plants in central Canada, and provide a basis for assessing burial tolerance in woody plants on coastal dunes throughout the world.

Influence of nonnative and native ungulate biomass and seasonal precipitation on vegetation production in a Great Basin ecosystem

USGS Publications Warehouse

Zeigenfuss, Linda C.; Schoenecker, Kathryn A.; Ransom, Jason I.; Ignizio, Drew A.; Mask, Tracy

2014-01-01

The negative effects of equid grazers in semiarid ecosystems of the American West have been considered disproportionate to the influence of native ungulates in these systems because of equids' large body size, hoof shape, and short history on the landscape relative to native ungulates. Tools that can analyze the degree of influence of various ungulate herbivores in an ecosystem and separate effects of ungulates from effects of other variables (climate, anthropomorphic disturbances) can be useful to managers in determining the location of nonnative herbivore impacts and assessing the effect of management actions targeted at different ungulate populations. We used remotely sensed data to determine the influence of native and nonnative ungulates and climate on vegetation productivity at wildlife refuges in Oregon and Nevada. Our findings indicate that ungulate biomass density, particularly equid biomass density, and precipitation in winter and spring had the greatest influence on normalized difference vegetation index (NDVI) values. Our results concur with those of other researchers, who found that drought exacerbated the impacts of ungulate herbivores in arid systems.

Fuel dynamics and fire behaviour in Australian mallee and heath vegetation

Treesearch

Juanita Myers; Jim Gould; Miguel Cruz; Meredith Henderson

2007-01-01

In southern Australia, shrubby heath vegetation together with woodlands dominated by multistemmed eucalypts (mallee) comprise areas of native vegetation with important biodiversity values. These vegetation types occur in semiarid and mediterranean climates and can experience large frequent fires. This study is investigating changes in the fuel complex with time, fuel...

A global synthesis of plant extinction rates in urban areas.

PubMed

Hahs, Amy K; McDonnell, Mark J; McCarthy, Michael A; Vesk, Peter A; Corlett, Richard T; Norton, Briony A; Clemants, Steven E; Duncan, Richard P; Thompson, Ken; Schwartz, Mark W; Williams, Nicholas S G

2009-11-01

Plant extinctions from urban areas are a growing threat to biodiversity worldwide. To minimize this threat, it is critical to understand what factors are influencing plant extinction rates. We compiled plant extinction rate data for 22 cities around the world. Two-thirds of the variation in plant extinction rates was explained by a combination of the city's historical development and the current proportion of native vegetation, with the former explaining the greatest variability. As a single variable, the amount of native vegetation remaining also influenced extinction rates, particularly in cities > 200 years old. Our study demonstrates that the legacies of landscape transformations by agrarian and urban development last for hundreds of years, and modern cities potentially carry a large extinction debt. This finding highlights the importance of preserving native vegetation in urban areas and the need for mitigation to minimize potential plant extinctions in the future.

Aeolian sand as a tool for understanding Mars: Thermal infrared remote sensing of volcaniclastic Mars-analog sand dunes in Christmas Lake Valley, Oregon, U.S.A.

NASA Astrophysics Data System (ADS)

Edgett, Kenneth S.

1996-10-01

INTRODUCTION: On Earth, aeolian sand dunes are used as tools of scientific inquiry. Holocene and Pleistocene dunes preserve clues about Quaternary climate variations and human activities ranging from Ice Age hunting practices to Twentieth Century warfare. Modern dunes contain the sedimentary textures and structures necessary for interpreting ancient sandstones, and they provide natural laboratories for investigation of aeolian physics and desertification processes. The dunes of Mars can likewise be used as scientific tools. Dunes provide relatively dust-free surfaces. From a remote sensing perspective, martian dunes have much potential for providing clues about surface mineralogy and the interaction between the surface and atmosphere. Such information can in turn provide insights regarding crust composition, volcanic evolution, present and past climate events, and perhaps weathering rates. The Mars Global Surveyor Thermal Emission Spectrometer (TES) is expected to reach the planet in September 1997. TES will provide 6 to 50 micrometer spectra of the martian surface at ground resolutions of 3 to 9 km. Sandy aeolian environments on Mars might provide key information about bedrock composition. To prepare for the TES investigation, I have been examining a thermal infrared image of a Mars-composition analog dune field in Christmas Lake Valley, Oregon. COMPOSITION AND GEOLOGIC SETTING: The "Shifting Sand Dunes" dune field is located at the eastern end of Christmas Lake Valley, in what was once the Pleistocene Fort Rock Lake [1]. Much of the sand that makes up the Shifting Sand Dunes dune field is reworked Mt. Mazama airfall from its terminal eruption 6,800 years ago, plus material deflated from the lake bed [1, 2]. The main constituents of the dunes are volcanic glass and devitrified glass fragments, plagioclase crystals, basalt lithic fragments, aggregates of silt and clay-size volcanic ash, pyroxenes, opaque oxide minerals (mostly magnetite), and trace occurrences of fossil fragments and other minerals [3]. THERMAL INFRARED IMAGE: The thermal infrared images used in this study was obtained by the NASA Ames Research Center C-130 Earth Resources airborne Thermal Infrared Multispectral Scanner (TIMS) on 21 September 1991. The image has 6 spectral bands between 8 and 12 micrometers and a ground resolution of 9 m/pixel. The raw image was converted to calibrated radiance, from which normalized emittance was computed for each of the six bands, following the method of Realmutto [4]. Atmospheric effects were corrected using an empirical method described by Edgett and Anderson [5]. The resulting 6-band image provides quantitative determination of the surface emissivity. Dune spectra in the image match spectra obtained in our laboratory using samples collected from the field area [3, 5]. ACTIVE DUNES, INACTIVE DUNES, AND INTERDUNE AREAS FROM EMISSIVITY VARIATION: This study shows that in a modern dune field, the location of active dunes, interdune surfaces, and inactive dunes can be mapped using emissivity in the thermal infrared band that shows the most spectral variation [6]. In this case, TIMS band 3 (9.2 micrometers) had the most variation, although the entire emissivity range was only from 0.89 to 1.0. Active dunes had the lowest emissivities (0.89 to 0.91), inactive dunes were distinguished by higher emissivities (.094 to 1.0), and interdune surfaces had intermediate values (0.90 to 0.95). These emissivity variations result from differences in particle size, as inactive dunes tend to have finer-grained silt and dust on them. LINEAR UNMIXING USING IMAGE ENDMEMBERS: Quantitative estimates of thermal infrared spectral emissivity are ideally suited to unmixing analysis. For grains larger than the wavelength (e.g., dune sand), a linear unmixing approach provides geologically useful results [7]. In the present study, image endmembers were selected for a preliminary unmixing study: (1) "regular sand," which contains nearly 50% plagioclase and nearly 20% volcanic glass; (2) "dark sand, which consists mainly of basalt clasts (> 25%) and glass (> 30%); (3) "mud chips," which are volcanic ash aggregates broken into sand-sized pieces, (4) sagebrush and grass; and (5) thick vegetation, such as an alfalfa farm near the dunes. The most important result of this preliminary unmixing work is an image that shows the distribution of ash aggregates and "dark sand," both of which vary throughout the dune field as a function of proximity to the source. The volcanic ash aggregates, in particular, are locally eroded from a layer that caps the Pleistocene lake beds that underlie the dunes [3]. SUMMARY: This study highlights the use of thermal infrared spectra to map local contributions of sand to a dune field, and to distinguish active versus inactive dune fields. Mapping of local contributions to active dune fields on Mars using TES or other multispectral images has potential to provide indications of local bedrock composition. REFERENCES: [1] Allison, I. S. (1979) Oregon Dept. Geol. Minl. Res. Spec. Pap. 7. [2] Dole, H. M. (1942) M.S. Thesis, Oregon State, Corvallis, Or. [3] Edgett, K. S. (1994) in Ph.D. Diss., pp. 145-201, Arizona State, Tempe, AZ. [4] Realmutto, V. J. (1990) in JPL Publ. 90-55, pp. 31-35. [5] Edgett, K. S., and D. L. Anderson (1995) in JPL Publ. 95-1, v. 2, pp. 9-12. [6] Edgett, K. S. et al. (1995) in JPL Publ. 95-1, v. 2, pp. 13-16. [7] Ramsey, M. S. (1996) Ph.D. Diss, Arizona State, Tempe, AZ.

Vegetation component of geothermal EIS studies: Introduced plants, ecosystem stability, and geothermal development

NASA Astrophysics Data System (ADS)

1994-10-01

This paper contributes new information about the impacts from introduced plant invasions on the native Hawaiian vegetation as consequences of land disturbance and geothermal development activities. In this regard, most geothermal development is expected to act as another recurring source of physical disturbance which favors the spread and maintenance of introduced organisms throughout the region. Where geothermal exploration and development activities extend beyond existing agricultural and residential development, they will become the initial or sole source of disturbance to the naturalized vegetation of the area. Kilauea has a unique ecosystem adapted to the dynamics of a volcanically active landscape. The characteristics of this ecosystem need to be realized in order to understand the major threats to the ecosystem and to evaluate the effects of and mitigation for geothermal development in Puna. The native Puna vegetation is well adapted to disturbances associated with volcanic eruption, but it is ill-adapted to compete with alien plant species in secondary disturbances produced by human activities. Introduced plant and animal species have become a major threat to the continued presence of the native biota in the Puna region.

Selective herbicide applications for low impact vegetation management of exotic species and enhancement of native plant communities

Treesearch

Max Williamson

1998-01-01

Selective and specific management for the control of exotic (non-native) plants is necessary for preservation of native plant communities. Managers of federal, state, or county land holdings and parks, wildlife areas, recreation areas, and historic sites are frequently charged with selectively managing the enhancement of desirable or native plant communities. In...

Vegetation response of a dry shrubland community to feral goat management on the island of Moloka‘i, Hawai‘i

USGS Publications Warehouse

Jacobi, James D.; Stock, Jonathan

2017-12-14

The Hawaiian Islands are well known for their unique ecosystem assemblages that have a high proportion of endemic flora and fauna. However, since human colonization of this archipelago—starting with the arrival of Polynesian sailors approximately 1,200 years ago, and particularly following western contact in 1778—thousands of non-native species have been introduced to the Islands and many of these alien species have had severe impacts on the native ecosystems. Particularly damaging to these ecosystems are large mammals, including goats (Capra hircus), pigs (Sus scrofa), cattle (Bos taurus), deer (Axis axis and Odocoileus hemionus), and sheep (Ovis spp.), which are collectively referred to here as ungulates; they cause extensive damage to the native vegetation by their browsing, grazing, and trampling. Similar impacts have been documented elsewhere, including New Zealand and many other island ecosystems.Previous studies in Hawai‘i have utilized fenced exclosures to assess the impacts of feral or wild ungulates on vegetation and the recovery potential for the native plant communities by comparing plant community composition, structure, and cover inside the fenced area (without ungulates) over time to the vegetation condition outside of the protection of the fence. In some cases, the native vegetation recovered once the animals were removed. However, in other situations alien plants were more competitive and dominated the revegetation process after the impacts of ungulates had been reduced or eliminated.This report describes the response of a highly degraded lowland dry habitat plant community located on the south slope of east Moloka‘i, Hawai‘i, to reduction of browsing and grazing impacts caused by feral goats. For this study, vegetation response inside a fenced exclosure was compared to vegetation change in the area outside of the fence that was still accessible to goats. This study is part of the larger U.S. Geological Survey Ridge-to-Reef (USGS-R2R) research project conducted between 2008 and 2014 to better understand the magnitude of, and factors responsible for, increased erosion on Moloka‘i. The upslope erosion has resulted in heavy sedimentation of the near-shore coral reef ecosystem on the leeward side of the island. The project area and adjacent lands are managed by the East Moloka‘i Watershed Partnership (EMoWP) to restore the vegetation and reduce erosion on the leeward side of the island.Specific questions addressed in this vegetation change study include:How does the vegetation composition, structure, and cover respond to different population levels of feral goats in this area?Are there plant species that can be used as indicators of different population levels of goats?Can native plants recover and become dominant again with the reduction or elimination of goats from this area?Are there invasive plant species that respond favorably to reduction of goat populations and could result in additional management threats to this area over time?How does the succession of vegetation following goat control relate to the original composition and structure of the plant communities that were formerly found in this area?

The Karakum and Kyzylkum sand seas dynamics; mapping and palaeoclimatic interpretations

NASA Astrophysics Data System (ADS)

Maman, Shimrit; Blumberg, Dan G.; Tsoar, Haim; Porat, Naomi

2015-04-01

Sand seas are large basins in deserts that are mantled by wind-swept sand and that exhibit varying degrees of vegetation cover. Wilson (1973) was the first to globally map and classify sand seas. Beyond Wilson's maps, however, little research has been published regarding the Karakum and Kyzylkum sand seas of Central Asia. Wilson's maps delineate active ergs from inactive ergs based solely on precipitation. His assumption of annual average rainfall as a factor determining mobility vs. stability of sand seas is too simplistic and does not take into consideration other factors such as biogenic soil crusts and wind power, both of which are known to have major effects on the dynamics of sand dunes. Literature related to mapping and classifying the Central Asian ergs by remote sensing or sand sea classification state (stable/active) is lacking. Moreover, the palaeoclimatic significance of dunes in Central Asia is difficult to assess, as there has been few studies of dune stratigraphy and numerical ages are lacking. Optically stimulated luminescence (OSL) is a firm optical dating method that is used to determine the elapsed time since quartz grains were last exposed to sunlight, thus, their burial. Yet, absolute ages indicating mobilization and stabilization of these sands, are still inadequately known and are here under discussion. The broad concern of this research was to determine the dynamics of the Central Asian sand seas and study the palaeoclimatic changes that brought to their stabilization. As there are no reliable maps or aeolian discussion of these sands, establishment of a digital data base was initially conducted, focusing on identifying and mapping these sand seas. The vast area and inaccessibility make traditional mapping methods virtually impossible. A variety of space-borne imagery both optical and radar, with varying spectral and spatial resolutions was used. These images provided the basis for mapping sand distribution, dune forms, and vegetation cover. GIS analysis was performed in parallel with field work to obtain validation and verification. The remote sensing and GIS results show that these ergs are mostly stabilized, with the estimated sand mantled area for the Karakum desert ~260,000 km2, and for the Kyzylkum it is ~195,500 km2. Meteorological analysis of wind and precipitation data indicate a low wind power environment (DP< 200) and sufficient rainfall (>100 mm) to support vegetation. Thus, these sands are indicative of past periods during which the climate in this region was different than today, enabling aeolian sand activity. Optically stimulated luminescence ages derived from the upper meter of the interdune of 14 exposed sections from both ergs, indicate sand stabilization during the mid-Holocene. This stabilization is understood to reflect a transition to a warmer, wetter, and less windy climate that generally persisted until today. The OSL ages, coupled with a compilation of regional palaeoclimatic data, corroborate and reinforce the previously proposed Mid-Holocene Liavliakan phase, known to reflect a warmer, wetter, and less windy climate that persists until today and resulted in dune stabilization around the Mid-Holocene.

Bidirectional recovery patterns of Mojave Desert vegetation in an aqueduct pipeline corridor after 36 years: II. Annual plants

USGS Publications Warehouse

Berry, Kristin H.; Mack, Jeremy S.; Weigand, James F.; Gowan, Timothy A.; LaBerteaux, Denise

2015-01-01

We studied recovery of winter annual plants in a 97-m wide disturbed aqueduct corridor in the Mojave Desert 36 years after construction. We established plots at 0, 20, and 40 m from the road verge at the corridor center and at 100 m in undisturbed vegetation. We recorded 47 annual species, of which 41 were native and six were exotic. Exotic species composed from 64 to 91% of total biomass. We describe a bilateral process of recovery: from the road verge to the outward edge of the corridor and from undisturbed habitat into the corridor. Native annual plants significantly increased in richness from road verge to undisturbed vegetation, but not in density, biomass, or cover. In contrast, exotic annual plants increased in density, biomass, cover and richness with increasing distance from the road verge. The species of colonizing shrubs and type of canopy cover affected density, biomass, and richness of annuals. Species composition of native annuals differed significantly by distance, suggesting secondary succession. In general, native annuals were closer to achieving recovery on the 40-m plots than at the road verge. Recovery estimates were in centuries and dependent on location, canopy type, and whether considering all annuals or natives only.

Computer-aided analysis of LANDSAT data for surveying Texas coastal zone environments. [Pass Cavallo and Port O'Conner

NASA Technical Reports Server (NTRS)

Kristof, S. J. (Principal Investigator); Weismiller, R. A.

1977-01-01

The author has identified the following significant results. The study areas were Pass Cavallo and Port O'Connor. The following terrestrial and aquatic environments were discriminated: alternating beach ridges, swales, sand dunes, beach birms, deflation surfaces, land-water interface, urban, spoil areas, fresh and salt water marshes, grass and woodland, recently burned or grazed areas, submerged vegetation, and waterways.

Long-term effects of burn severity on non-native plant cover

USDA-ARS?s Scientific Manuscript database

Effects of burn severity on non-native plant invasion post-fire is of great concern to managers and researchers, especially given predicted increases in large, high severity fires. However, little else is known about long-term (>10 year) vegetation recovery and non-native plant persistence. We anal...

Spatial differences of aeolian desertification responses to climate in arid Asia

NASA Astrophysics Data System (ADS)

Wang, Xunming; Hua, Ting; Lang, Lili; Ma, Wenyong

2017-01-01

Most areas of arid Asia are covered by aeolian dunes, sand sheets, gravels, and desert steppes, and may jeopardize nearly 350 million people if climate change increases aeolian desertification. Although the aeolian desertification is mainly triggered by climate changes are extensively acknowledged, the responses of aeolian desertification to various climate scenarios are poorly understood. Based on the tight combinations of dune activity index (DAI) trends and of aeolian desertification, here the spatial differences of aeolian desertification responses on various climate scenarios were reported. The analyzed results show that the variations in temperature, precipitation and wind regime have no significant contributions on aeolian desertification in the extremely arid Asia. From the early to blooming periods of vegetation growth, although temperature rise may benefit vegetation growths in some high latitudes and altitudes, the temperature rise may increase aeolian desertification in most arid Asia regions such as Mongolia, West and Central Asia. In arid Asia, although precipitation increases may benefit the rehabilitation, decreases in precipitation is not the key role on aeolian desertification occurrences in extremely arid regions. From the early to blooming periods of vegetation growths, spatial trends of the sensitivity of aeolian desertification to wind regime varied. Generally, at the regional scales there are relative high sensitivities for aeolian desertification to climate changes in the eastern and western regions of arid Asia, and the climate changes may not play important roles on aeolian desertification occurrence in the central regions. The spatial differences of aeolian desertification responses to climate changes indicate various strategies for aeolian desertification combating are needed in different regions of arid Asia.

Impacts of Vegetation Change on the Water Balance of Superficial, Coastal Aquifers: a Comparative Study of Pre-clearing and Post-clearing Recharge Under Native Vegetation, and Pine Plantations

NASA Astrophysics Data System (ADS)

Bekele, E. B.; Salama, R. B.

2003-12-01

Replacing native vegetation with pasture across the northern Perth Basin in Western Australia has profoundly altered the water balance and led to dramatic increases in recharge and groundwater levels from about the mid-1960's, whereas replacing native vegetation with pine plantations and market gardens further south in the Gnangara groundwater Mound together with declining rainfall has caused continuous declines in recharge and water levels. Long-term monitoring of water levels in the Parmelia Formation, a superficial, semi-confined aquifer of predominantly weathered sand in the northern Perth Basin, indicates maximum rates of water level rise on the order of 40 to 55 cm/yr within the past decade. In the Gnangara Mound, water levels are falling by 10 to 20 cm/yr in the unconfined aquifer. Quantifying groundwater capture due to the removal of native vegetation is crucial for predicting the extent of groundwater development in the northern Perth Basin, whereas in the Gnangara Mound, it is necessary to limit the total water use to the declining resource to arrest the trend in falling water levels. Estimates of groundwater recharge before the removal of native vegetation in the northern Perth Basin determined from chloride tracer measurements in the soil water beneath native bushland and from groundwater samples ranged from 12 to 16 mm/yr, while estimates from soil water flux at the water table are approximately 5 mm/yr. In contrast, recharge estimates under cleared conditions since 1970 are between 24 and 50 mm/yr, based on hydrograph analyses of different bores. CFC and chloride analyses of water sampled from piezometers screened at the water table gave recharge estimates of 20 to 30 mm/yr and less than 10 mm/yr, respectively. In the Gnangara Mound recharge varies between 70 to 200 mm/year; the lowest recharge values were under the pines and the highest in the urban areas. Due to increasing demand on the groundwater resources and the declining water levels, additional resources can be provided only by removing the pine plantations, proper management of the Banksia woodland areas and capture of fresh groundwater discharging to the sea.

Variations of deep soil moisture under different vegetation types and influencing factors in a watershed of the Loess Plateau, China

NASA Astrophysics Data System (ADS)

Fang, Xuening; Zhao, Wenwu; Wang, Lixin; Feng, Qiang; Ding, Jingyi; Liu, Yuanxin; Zhang, Xiao

2016-08-01

Soil moisture in deep soil layers is a relatively stable water resource for vegetation growth in the semi-arid Loess Plateau of China. Characterizing the variations in deep soil moisture and its influencing factors at a moderate watershed scale is important to ensure the sustainability of vegetation restoration efforts. In this study, we focus on analyzing the variations and factors that influence the deep soil moisture (DSM) in 80-500 cm soil layers based on a soil moisture survey of the Ansai watershed in Yan'an in Shanxi Province. Our results can be divided into four main findings. (1) At the watershed scale, higher variations in the DSM occurred at 120-140 and 480-500 cm in the vertical direction. At the comparable depths, the variation in the DSM under native vegetation was much lower than that in human-managed vegetation and introduced vegetation. (2) The DSM in native vegetation and human-managed vegetation was significantly higher than that in introduced vegetation, and different degrees of soil desiccation occurred under all the introduced vegetation types. Caragana korshinskii and black locust caused the most serious desiccation. (3) Taking the DSM conditions of native vegetation as a reference, the DSM in this watershed could be divided into three layers: (i) a rainfall transpiration layer (80-220 cm); (ii) a transition layer (220-400 cm); and (iii) a stable layer (400-500 cm). (4) The factors influencing DSM at the watershed scale varied with vegetation types. The main local controls of the DSM variations were the soil particle composition and mean annual rainfall; human agricultural management measures can alter the soil bulk density, which contributes to higher DSM in farmland and apple orchards. The plant growth conditions, planting density, and litter water holding capacity of introduced vegetation showed significant relationships with the DSM. The results of this study are of practical significance for vegetation restoration strategies, especially for the choice of vegetation types, planting zones, and proper human management measures.

Effects of eradication and restoration treatments on Italian thistle (Carduus pycnocephalus)

USGS Publications Warehouse

McGinnis, Thomas; Keeley, Jon

2011-01-01

Low elevation grasslands in California long have been dominated by Mediterranean grasses, but many areas still have large native forb populations. Alien forbs invade these grasslands, displacing both native and other alien species. Italian thistle is a noxious alien herb that has recently invaded these grasslands, including ungrazed blue oak (Quercus douglassii) and interior live oak (Quercus wislizenii) stands in Sequoia National Park. Here, Italian thistle tends to dominate under oaks and has the potential to substantially alter the foothill ecosystem by displacing native plants and acting as a ladder fuel that can carry fires into the oak canopy. We tested the effects of selectively reducing Italian thistle populations alone and in combination with restoration of native species. Two thistle eradication techniques (clipping and the application of clopyralid herbicide) and two restoration techniques (addition of native forb seeds or planting native grass plugs) were used. After two consecutive years of treatment we found: a) clipping was not effective at reducing Italian thistle populations (clipping reduced Italian thistle density in some areas, but not vegetative cover), b) herbicide reduced both Italian thistle density and vegetative cover for the first two growing seasons after application, but cover rebounded in the third growing season, c) native forb cover and species richness were not significantly affected by clipping or spot-treating with herbicide, d) the grass and forb addition treatments by themselves were not effective at reducing Italian thistle during the course of this study and e) sowing annual forb seeds after clipping resulted in greater forb cover and moderately reduced Italian thistle vegetative cover in the short term.

Identification and mapping of natural vegetation on a coastal site using a Worldview-2 satellite image.

PubMed

Rapinel, Sébastien; Clément, Bernard; Magnanon, Sylvie; Sellin, Vanessa; Hubert-Moy, Laurence

2014-11-01

Identification and mapping of natural vegetation are major issues for biodiversity management and conservation. Remotely sensed data with very high spatial resolution are currently used to study vegetation, but most satellite sensors are limited to four spectral bands, which is insufficient to identify some natural vegetation formations. The study objectives are to discriminate natural vegetation and identify natural vegetation formations using a Worldview-2 satellite image. The classification of the Worldview-2 image and ancillary thematic data was performed using a hybrid pixel-based and object-oriented approach. A hierarchical scheme using three levels was implemented, from land cover at a field scale to vegetation formation. This method was applied on a 48 km² site located on the French Atlantic coast which includes a classified NATURA 2000 dune and marsh system. The classification accuracy was very high, the Kappa index varying between 0.90 and 0.74 at land cover and vegetation formation levels respectively. These results show that Wordlview-2 images are suitable to identify natural vegetation. Vegetation maps derived from Worldview-2 images are more detailed than existing ones. They provide a useful medium for environmental management of vulnerable areas. The approach used to map natural vegetation is reproducible for a wider application by environmental managers. Copyright © 2014 Elsevier Ltd. All rights reserved.

Investing in rangeland restoration in the Arid West, USA: countering the effects of an invasive weed on the long-term fire cycle.

PubMed

Epanchin-Niell, Rebecca; Englin, Jeffrey; Nalle, Darek

2009-01-01

In large areas of the arid western United States, much of which are federally managed, fire frequencies and associated management costs are escalating as flammable, invasive cheatgrass (Bromus tectorum) increases its stronghold. Cheatgrass invasion and the subsequent increase in fire frequency result in the loss of native vegetation, less predictable forage availability for livestock and wildlife, and increased costs and risk associated with firefighting. Revegetation following fire on land that is partially invaded by cheatgrass can reduce both the dominance of cheatgrass and its associated high fire rate. Thus restoration can be viewed as an investment in fire-prevention and, if native seed is used, an investment in maintaining native vegetation on the landscape. Here we develop and employ a Markov model of vegetation dynamics for the sagebrush steppe ecosystem to predict vegetation change and management costs under different intensities and types of post-fire revegetation. We use the results to estimate the minimum total cost curves for maintaining native vegetation on the landscape and for preventing cheatgrass dominance. Our results show that across a variety of model parameter possibilities, increased investment in post-fire revegetation reduces long-term fire management costs by more than enough to offset the costs of revegetation. These results support that a policy of intensive post-fire revegetation will reduce long-term management costs for this ecosystem, in addition to providing environmental benefits. This information may help justify costs associated with revegetation and raise the priority of restoration in federal land budgets.

Effects of ungulate management on vegetation at Hakalau Forest National Wildlife Refuge, Hawai'i Island

USGS Publications Warehouse

Hess, S.C.; Jeffrey, J.J.; Pratt, L.W.; Ball, D.L.

2010-01-01

We compiled and analysed data from 1987-2004 on vegetation monitoring during feral ungulate management at Hakalau Forest National Wildlife Refuge, a tropical montane rainforest on the island of Hawai'i All areas in the study had previously been used by ungulates, but cattle (Bos taurus) were removed and feral pig (Sus scrofa) populations were reduced during the study period. We monitored six line-intercept transects, three in previously high ungulate use areas and three in previously low ungulate use areas. We measured nine cover categories with the line-intercept method: native ferns; native woody plants; bryophytes; lichens; alien grasses; alien herbs; litter; exposed soil; and coarse woody debris. Vegetation surveys were repeated four times over a 16-year period. Vegetation monitoring revealed a strong increase in native fern cover and slight decreases in cover of bryophytes and exposed soil. Mean cover of native plants was generally higher in locations that were formerly lightly grazed, while alien grass and herb cover was generally higher in areas that were heavily grazed, although these effects were not statistically significant. These responses may represent early serai processes in forest regeneration following the reduction of feral ungulate populations. In contrast to many other Hawaiian forests which have become invaded by alien grasses and herbs after ungulate removal, HFNWR has not experienced this effect.

Understanding smallholders’ intended deforestation behavior in the Brazilian Cerrado following environmental registry

NASA Astrophysics Data System (ADS)

Vang Rasmussen, Laura; Jung, Suhyun; Dantas Brites, Alice; Watkins, Cristy; Agrawal, Arun

2016-09-01

Brazil’s Rural Environmental Registry (CAR) is a potentially promising avenue to slow deforestation on private properties as it facilitates the monitoring of land use. Yet limited empirical evidence exists on how the CAR affects smallholders’ behavior and recent scholarly efforts have in fact indicated that it may be doing less to protect forests than previously assumed. Based on 1177 smallholder surveys conducted in the Cerrado, we assess 1) whether the CAR might incentivize smallholders to pursue deforestation and 2) which factors are associated with smallholders’ intended deforestation behavior. We find that upon CAR registration, factors significantly associated with smallholders’ intention to deforest are: the existing percentage of native vegetation on the property, the use of agricultural loans, property owner’s age, and livestock production experience. To curb deforestation that may follow expressed intentions of smallholders, the CAR, and environmental registration programs alike, should account for existing land use by, for example, improving the system already in place for trading areas of native vegetation as this system is not widely adopted by those smallholders with more native vegetation than the legal cut-off. Also, such programs should assess the role of whether conditions related to land cover maintenance may protect against deforestation if credit access is supported especially to younger smallholders and/or livestock producers with a high percentage of native vegetation in their properties.

Application of remote sensing in the study of vegetation and soils in Idaho

NASA Technical Reports Server (NTRS)

Tisdale, E. W. (Principal Investigator)

1973-01-01

The author has identified the following significant results. Comparison of ERTS-1 imagery and USGS 1:250,000 scale maps of study areas with known ground points revealed significant map errors. These errors were sufficient to render impractical the projection of ERTS-1 imagery directly onto maps of the area. Marked differences were found in the delineation of ground features by different MSS bands. Generally, Band 4 was least useful, while Band 5 proved valuable for indicating patterns of native vegetation, cultivated areas - both dry and irrigated, lava fields, drainage basins, and deep bodies of water. Band 6 was better for landforms and drainages and for shallow bodies of water than Band 5 but inferior for indicating patterns in native vegetation and most types of cultivated land. Band 7 was best of all for indicating lava flows, water bodies, and landform features. Use of a additive color viewer-projector aided greatly in separation of images. A combination of Bands 5 and 7 with appropriate color filters proved best for separating most types of native vegetation and cultivated crops. Landform features and water bodies also showed well with this combination. The addition of Band 4 imagery to these further enhanced the identification of semi-dormant vegetation.

Native American impacts on fire regimes of the California coastal ranges

USGS Publications Warehouse

Keeley, Jon E.

2002-01-01

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

A methodological approach to assess beach-dune system susceptibility to erosion. Cases studies from Valdelagrana spit (Spain) and Campomarino beach (Italy).

NASA Astrophysics Data System (ADS)

Rizzo, Angela; Aucelli, Pietro P. C.; Gracia, Javier F.; Anfuso, Giorgio; Rosskopf, Carmen M.

2016-04-01

Dunes provide many important services to coastal areas, such as coastal erosion mitigation, coastal flooding protection and biological diversity. Their dynamic equilibrium and geomorphological evolution are the result of the interaction between marine and aeolian processes. Moreover, coastal dunes are characterized by a high ecological value, being a narrow strip between marine and terrestrial ecosystems and are habitats considered of community interest by the Habitats Directive 92/43/EEC. In the meantime, the significant increase of human pressure on coastal environments during the last decades has caused a strong alteration and an increase of the fragility and fragmentation of these habitats. This paper presents a methodological approach for the assessment of the beach-dune system susceptibility to erosion. The aim is to identify, at the local scale, the degree of susceptibility of coastal stretches in order to evaluate the degree of exposure of human settlements and natural environments located behind the dune system and to support actuations to appropriately improve dune management and conservation. A coastal susceptibility matrix and a corresponding Coastal Susceptibility Index (CSI) are proposed. Following the assumption that a good index should be based on a minimum amount of essential information (Cooper and McLaughlin, 1998), possibly already available or easy to be obtained (Villa and McLeod, 2002), the proposed index consisted into eight variables concerning existing beach and dune conditions, covering geomorphological, physical and anthropogenic aspects. Each variable was inserted into a GIS system and overlapped with the others through a logical overlay operation. The resulting layer was reclassified according to the formula proposed by Rangel and Anfuso (2015) allowing to calculate the CSI, which ranged from 1 (null/very low susceptibility) to 5 (very high susceptibility). In a further step, the predominant processes occurred in the last decades were considered by taking into account the medium term evolution (approx. 30 years) of the dune toe and dune vegetation cover. The proposed methodology was tested for two coastal sectors with different physiographic and marine conditions and different land use characteristics: the Valdelagrana beach and the Campomarino beach that are respectively located in the eastern part of the Gulf of Cadiz (Spain) and in the southern part of the Molise coastal stretch (Italy). Preliminary results show that the methodology allows identifying within the studied coastal sectors coast stretches with different degree of susceptibility. It is furthermore very advantageous as it requires parameters mostly already available through photo-interpretation, therefore it is easy to apply without requiring field surveys as do many other index-based methods.

Earth Observations taken during Expedition 16 / STS-120 Joint Operations

NASA Image and Video Library

2007-10-26

ISS016-E-006986 (26 Oct. 2007) --- Great Sand Dunes National Park and Preserve, Colorado is featured in this image photographed by an Expedition 16 crewmember on the International Space Station. The Sangre de Cristo Mountains of south-central Colorado stretch dramatically from top left to lower right of this image, generally outlined by the dark green of forests with white snow-capped peaks on the highest elevations. Dun-colored dunes, covering an area of 80 square kilometers, are banked up on the west side of the mountains and comprise the Great Sand Dunes National Park and Preserve. Originally established in 1932 as a National Monument, it was reauthorized as a National Park in 2004. The park contains dunes over 750 feet (227 meters) high -- among the highest in North America. Sand grains that make up the dunes are small enough to be moved along by the wind (a process known as saltation), although much of the dunefield is now anchored by vegetation. Predominant winds blow broadly to the east, so that sand in the San Luis valley (part of which appears at lower left) is driven towards and piled against the Sangre de Cristo Mts. The sand of the dunes is mostly derived from ancient exposed lakebed sediments - now the floor of the San Luis valley - formed by erosion of rocks in the Sangre de Cristo and San Juan Mountains (located to the west). The action of streams and occasional storms today returns some of the impounded sand back to the valley, where the prevailing winds begin the sand's migration to the dunefield anew. Interestingly, the specific location of the sand field appears to be related to a locally lower altitude sector of the Sangre de Cristo Mts. Altitudes can be inferred from the distribution of snow cover on the day this image was taken. Areas to the north (Cleveland Peak and northward) of the dunefield, and to the south around Blanca Peak, are higher than the ridgeline next to the dune field where almost no snow is visible. Since winds are preferentially channeled over the lower parts of any range (hundreds of meters lower here than ridgelines to north and south), sand grains are carried up to (but not over) the low point of the range.

Using Species Distribution Models to Predict Potential Landscape Restoration Effects on Puma Conservation

PubMed Central

Angelieri, Cintia Camila Silva; Adams-Hosking, Christine; Ferraz, Katia Maria Paschoaletto Micchi de Barros

2016-01-01

A mosaic of intact native and human-modified vegetation use can provide important habitat for top predators such as the puma (Puma concolor), avoiding negative effects on other species and ecological processes due to cascade trophic interactions. This study investigates the effects of restoration scenarios on the puma’s habitat suitability in the most developed Brazilian region (São Paulo State). Species Distribution Models incorporating restoration scenarios were developed using the species’ occurrence information to (1) map habitat suitability of pumas in São Paulo State, Southeast, Brazil; (2) test the relative contribution of environmental variables ecologically relevant to the species habitat suitability and (3) project the predicted habitat suitability to future native vegetation restoration scenarios. The Maximum Entropy algorithm was used (Test AUC of 0.84 ± 0.0228) based on seven environmental non-correlated variables and non-autocorrelated presence-only records (n = 342). The percentage of native vegetation (positive influence), elevation (positive influence) and density of roads (negative influence) were considered the most important environmental variables to the model. Model projections to restoration scenarios reflected the high positive relationship between pumas and native vegetation. These projections identified new high suitability areas for pumas (probability of presence >0.5) in highly deforested regions. High suitability areas were increased from 5.3% to 8.5% of the total State extension when the landscapes were restored for ≥ the minimum native vegetation cover rule (20%) established by the Brazilian Forest Code in private lands. This study highlights the importance of a landscape planning approach to improve the conservation outlook for pumas and other species, including not only the establishment and management of protected areas, but also the habitat restoration on private lands. Importantly, the results may inform environmental policies and land use planning in São Paulo State, Brazil. PMID:26735128

The effect of vegetation and soil texture on the nature of organics in runoff from a catchment supplying water for domestic consumption.

PubMed

Awad, John; van Leeuwen, John; Abate, Dawit; Pichler, Markus; Bestland, Erick; Chittleborough, David J; Fleming, Nigel; Cohen, Jonathan; Liffner, Joel; Drikas, Mary

2015-10-01

The influence of vegetation and soil texture on the concentration and character of dissolved organic matter (DOM) present in runoff from the surface and sub-surface of zero order catchments of the Myponga Reservoir-catchment (South Australia) was investigated to determine the impacts of catchment characteristics and land management practices on the quality of waters used for domestic supply. Catchments selected have distinct vegetative cover (grass, native vegetation or pine) and contrasting texture of the surface soil horizon (sand or clay loam/clay). Water samples were collected from three slope positions (upper, middle, and lower) at soil depths of ~30 cm and ~60 cm in addition to overland flows. Filtered (0.45 μm) water samples were analyzed for dissolved organic carbon (DOC) and UV-visible absorbance and by F-EEM and HPSEC with UV and fluorescence detection to characterize the DOM. Surface and sub-surface runoff from catchments with clay soils and native vegetation or grass had lower DOC concentrations and lower relative abundances of aromatic, humic-like and high molecular weight organics than runoff from sandy soils with these vegetative types. Sub-surface flows from two catchments with Pinus radiata had similar DOC concentrations and DOM character, regardless of marked variation in surface soil texture. Runoff from catchments under native vegetation and grass on clay soils resulted in lower DOC concentrations and hence would be expected to have lower coagulant demand in conventional treatment for potable water supply than runoff from corresponding sandy soil catchments. However, organics in runoff from clay catchments would be more difficult to remove by coagulation. Surface waters from the native vegetation and grass catchments were generally found to have higher relative abundance of organic compounds amenable to removal by coagulation compared with sub-surface waters. Biophysical and land management practices combine to have a marked influence on the quality of source water used for domestic supply. Copyright © 2015 Elsevier B.V. All rights reserved.

Remotely Monitoring Change in Vegetation Cover on the Montebello Islands, Western Australia, in Response to Introduced Rodent Eradication

PubMed Central

Lohr, Cheryl; Van Dongen, Ricky; Huntley, Bart; Gibson, Lesley; Morris, Keith

2014-01-01

The Montebello archipelago consists of 218 islands; 80 km from the north-west coast of Western Australia. Before 1912 the islands had a diverse terrestrial fauna. By 1952 several species were locally extinct. Between 1996 and 2011 rodents and cats were eradicated, and 5 mammal and 2 bird species were translocated to the islands. Monitoring of the broader terrestrial ecosystem over time has been limited. We used 20 dry-season Landsat images from 1988 to 2013 and estimation of green fraction cover in nadir photographs taken at 27 sites within the Montebello islands and six sites on Thevenard Island to assess change in vegetation density over time. Analysis of data averaged across the 26-year period suggests that 719 ha out of 2169 ha have increased in vegetation cover by up to 32%, 955 ha have remained stable and 0.6 ha have declined in vegetation cover. Over 492 ha (22%) had no vegetation cover at any time during the period analysed. Chronological clustering analysis identified two breakpoints in the average vegetation cover data occurring in 1997 and 2003, near the beginning and end of the rodent eradication activities. On many islands vegetation cover was declining prior to 1996 but increased after rodents were eradicated from the islands. Data for North West and Trimouille islands were analysed independently because of the potential confounding effect of native fauna being introduced to these islands. Mala (Lagorchestes hirsutus) and Shark Bay mice (Pseudomys fieldi) both appear to suppress native plant recruitment but not to the same degree as introduced rodents. Future research should assess whether the increase in vegetation cover on the Montebello islands is due to an increase in native or introduced plants. PMID:25436454

Evapotranspiration from areas of native vegetation in west-central Florida

USGS Publications Warehouse

Bidlake, W.R.; Woodham, W.M.; Lopez, Miguel Angel

1996-01-01

The micrometeorological methods of energy-balance Bowen ratio and eddy correlation probably are suitable for determining evapotranspiration from unforested sites, but the aerodynamic effects of tall tree canopies need to be considered when the methods are used for forested sites. Potential evapotranspiration methods might not yield reliable estimates of evapotranspiration for all areas of native vegetation. Estimates of annual evapotranspiration ranged from 970 millimeters for a cypress swamp site to 1,060 millimeters for a pine flatwood site.

The development of novel and non-invasive germplasm selections native to Arkansas for highway re-vegetation projects.

DOT National Transportation Integrated Search

2012-03-01

"Re-vegetation strategies and programs for highway rights of way in both rural and urban areas are an importatn component of any : highway construction project. Vegetation is ued to stabilize soils to prevent sheet and gully erosion and to help in so...

On modelling the relationship between vegetation greenness and water balance and land use change.

PubMed

Berry, Sandra L; Mackey, Brendan

2018-06-13

Here we sought a biologically meaningful, climate variable that captures water-energy availability and is suitable for high resolution (250 m × 250 m) modelling of the fraction of photosynthetically active radiation intercepted by the sunlit canopy (F V ) derived from a 10-year (July 2000 - June 2010) time series of Moderate Resolution Imaging Spectroradiometer (MODIS) Normalized difference vegetation index (NDVI) satellite imagery for Australia. The long-term mean annual evaporation deficit, and mean annual water availability indices all yielded strong linear relationships with mean F V ([Formula: see text], %). We hypothesised whether some of the scatter about the relationships was related to land-use changes that have disrupted the vegetation-climate-soil equilibrium. Using continental-scale spatial data layers of protected area status and vegetation condition classes we repeated our analyses with restricted datasets. [Formula: see text] of intact native vegetation within protected areas was greater than all modified vegetation classes. There was a consistent decline in the slopes of the regression relationships with increasing intensity of woody vegetation clearing and livestock grazing. Where native vegetation has been transformed by land use there was a 25% reduction in predicted [Formula: see text].

The behavioural ecology of two sympatric talitrid species, Talitrus saltator (Montagu) and Orchestia gammarellus (Pallas) on a Tyrrhenian sandy beach dune system

NASA Astrophysics Data System (ADS)

Colombini, Isabella; Fallaci, Mario; Gagnarli, Elena; Rossano, Claudia; Scapini, Felicita; Chelazzi, Lorenzo

2013-01-01

The behavioural ecology of a sub-population of Talitrus saltator living on the sandy shore of the Maremma Regional Park (Italy) was compared with that of Orchestia gammarellus inhabiting the retrodunal dune slack area. Monthly monitoring over a year determined the mean distribution patterns, their changes and whether these overlapped. Standard pitfall traps were placed along transects across the beach-dune-dune slack area. Experiments analysed the diel activity rhythms during spring and the activity patterns of the different age classes and the two sexes were compared within and between species. Local environmental conditions were registered with a microclimatic station. During May and September, plant hummocks were monitored to see whether surface movements of O. gammarellus could be restricted to certain periods of the year and to estimate densities within the vegetation. The plant biomass and moisture conditions within the hummocks were also recorded and substratum samples were collected at the base of the shrubs for laboratory analysis. To test for visual cues, orientation experiments with and without landscape view were carried out on the beach during morning and afternoon hours and contemporaneously for each species. Experiments to test the diel variation of scototaxis to a black shape were also performed over a 24 h period of time under controlled conditions. There was a spatial partitioning of the two species, with T. saltator moving along a sea-land axis according to diel and seasonal changes and with some individuals reaching the back of the dune in particular environmental conditions. No spatial overlap with the zonation patterns of O. gammarellus was observed, which was restricted to the dune slack area. Nocturnal surface activity was observed for both species with juveniles peaking at dawn and with O. gammarellus being strictly more nocturnal than T. saltator. Orientation experiments showed a higher ability of T. saltator to orient towards the shoreline using solar and local cues, whereas O. gammarellus seemed to have a stronger scototaxis. Differences in the behavioural responses are discussed in terms of the species ecological adaptations to their particular habitats.

Vegetation response to fire and postburn seeding treatments in juniper woodlands of the Grand Staircase-Escalante National Monument, Utah

USGS Publications Warehouse

Evangelista, P.; Stohlgren, T.J.; Guenther, D.; Stewart, S.

2004-01-01

We compared 3 naturally ignited burns with unburned sites in the Grand Staircase-Escalante National Monument. Each burn site was restored with native and nonnative seed mixes, restored with native seeds only, or regenerated naturally. In general, burned sites had significantly lower native species richness (1.8 vs. 2.9 species), native species cover (11% vs. 22.5%), and soil crust cover (4.1% vs. 15%) than unburned sites. Most burned plots, seeded or not, had significantly higher average nonnative species richness and cover and lower average native species richness and cover than unburned sites. Regression tree analyses suggest site variation was equally important to rehabilitation results as seeding treatments. Low native species richness and cover, high soil C, and low cover of biological soil crusts may facilitate increased nonnative species richness and cover. Our study also found that unburned sites in the region had equally high cover of nonnative species compared with the rest of the Monument. Cheatgrass (Bromus tectorum) dominated both burned and unburned sites. Despite the invasion of cheatgrass, unburned sites still maintain higher native species richness; however, the high cover of cheatgrass may increase fire frequency, further reduce native species richness and cover, and ultimately change vegetation composition in juniper woodlands.

Plant functional traits of dominant native and invasive species in mediterranean-climate ecosystems.

PubMed

Funk, Jennifer L; Standish, Rachel J; Stock, William D; Valladares, Fernando

2016-01-01

The idea that dominant invasive plant species outperform neighboring native species through higher rates of carbon assimilation and growth is supported by several analyses of global data sets. However, theory suggests that native and invasive species occurring in low-resource environments will be functionally similar, as environmental factors restrict the range of observed physiological and morphological trait values. We measured resource-use traits in native and invasive plant species across eight diverse vegetation communities distributed throughout the five mediterranean-climate regions, which are drought prone and increasingly threatened by human activities, including the introduction of exotic species. Traits differed strongly across the five regions. In regions with functional differences between native and invasive species groups, invasive species displayed traits consistent with high resource acquisition; however, these patterns were largely attributable to differences in life form. We found that species invading mediterranean-climate regions were more likely to be annual than perennial: three of the five regions were dominated by native woody species and invasive annuals. These results suggest that trait differences between native and invasive species are context dependent and will vary across vegetation communities. Native and invasive species within annual and perennial groups had similar patterns of carbon assimilation and resource use, which contradicts the widespread idea that invasive species optimize resource acquisition rather than resource conservation. .

Details of Layers in Victoria Crater's Cape St. Vincent

NASA Technical Reports Server (NTRS)

2007-01-01

NASA's Mars Exploration Rover Opportunity rover spent about 300 sols (Martian days) during 2006 and 2007 traversing the rim of Victoria Crater. Besides looking for a good place to enter the crater, the rover obtained images of rock outcrops exposed at several cliffs along the way.

The cliff in this image from Opportunity's panoramic camera (Pancam) is informally named Cape St. Vincent. It is a promontory approximately 12 meters (39 feet) tall on the northern rim of Victoria crater, near the farthest point along the rover's traverse around the rim. Layers seen in Cape St. Vincent have proven to be among the best examples of meter scale cross-bedding observed on Mars to date. Cross-bedding is a geologic term for rock layers which are inclined relative to the horizontal and which are indicative of ancient sand dune deposits. In order to get a better look at these outcrops, Pancam 'super-resolution' imaging techniques were utilized. Super-resolution is a type of imaging mode which acquires many pictures of the same target to reconstruct a digital image at a higher resolution than is native to the camera. These super-resolution images have allowed scientists to discern that the rocks at Victoria Crater once represented a large dune field, not unlike the Sahara desert on Earth, and that this dune field migrated with an ancient wind flowing from the north to the south across the region. Other rover chemical and mineral measurements have shown that many of the ancient sand dunes studied in Meridiani Planum were modified by surface and subsurface liquid water long ago.

This is a Mars Exploration Rover Opportunity Panoramic Camera image acquired on sol 1167 (May 7, 2007), and was constructed from a mathematical combination of 16 different blue filter (480 nm) images.

At the Crossroads: Does the Configuration of Roadside Vegetation Affect Woodland Bird Communities in Rural Landscapes?

PubMed Central

Hall, Mark; Nimmo, Dale; Bennett, Andrew F.

2016-01-01

In agricultural regions worldwide, linear networks of vegetation such as hedges, fencerows and live fences provide habitat for plant and animal species in heavily modified landscapes. In Australia, networks of remnant native vegetation along roadsides are a distinctive feature of many rural landscapes. Here, we investigated the richness and composition of woodland-dependent bird communities in networks of eucalypt woodland vegetation along roadsides, in an agricultural region in which >80% of native woodland and forest vegetation has been cleared. We stratified sites in a) cross sections and b) linear strips of roadside vegetation, to test the influence on woodland birds of site location and configuration in the linear network (the ‘intersection effect’). We also examined the influence of tree size at the site, the amount of wooded vegetation surrounding the site, and the abundance of an aggressive native species, the noisy miner Manorina melanocephala. Birds were surveyed at 26 pairs of sites (cross section or linear strip) on four occasions. A total of 66 species was recorded, including 35 woodland species. The richness of woodland bird species was influenced by site configuration, with more species present at cross sections, particularly those with larger trees (>30 cm diameter). However, the strongest influence on species richness was the relative abundance of the noisy miner. The richness of woodland birds at sites where noisy miners were abundant was ~20% of that where miners were absent. These results recognise the value of networks of roadside vegetation as habitat for woodland birds in depleted agricultural landscapes; but highlight that this value is not realised for much of this vast vegetation network because of the dominance of the noisy miner. Nevertheless, roadside vegetation is particularly important where the configuration of networks create nodes that facilitate movement. Globally, the protection, conservation and restoration of such linear networks has an important influence on the persistence of biota within human-dominated landscapes. PMID:27183227

At the Crossroads: Does the Configuration of Roadside Vegetation Affect Woodland Bird Communities in Rural Landscapes?

PubMed

Hall, Mark; Nimmo, Dale; Bennett, Andrew F

2016-01-01

In agricultural regions worldwide, linear networks of vegetation such as hedges, fencerows and live fences provide habitat for plant and animal species in heavily modified landscapes. In Australia, networks of remnant native vegetation along roadsides are a distinctive feature of many rural landscapes. Here, we investigated the richness and composition of woodland-dependent bird communities in networks of eucalypt woodland vegetation along roadsides, in an agricultural region in which >80% of native woodland and forest vegetation has been cleared. We stratified sites in a) cross sections and b) linear strips of roadside vegetation, to test the influence on woodland birds of site location and configuration in the linear network (the 'intersection effect'). We also examined the influence of tree size at the site, the amount of wooded vegetation surrounding the site, and the abundance of an aggressive native species, the noisy miner Manorina melanocephala. Birds were surveyed at 26 pairs of sites (cross section or linear strip) on four occasions. A total of 66 species was recorded, including 35 woodland species. The richness of woodland bird species was influenced by site configuration, with more species present at cross sections, particularly those with larger trees (>30 cm diameter). However, the strongest influence on species richness was the relative abundance of the noisy miner. The richness of woodland birds at sites where noisy miners were abundant was ~20% of that where miners were absent. These results recognise the value of networks of roadside vegetation as habitat for woodland birds in depleted agricultural landscapes; but highlight that this value is not realised for much of this vast vegetation network because of the dominance of the noisy miner. Nevertheless, roadside vegetation is particularly important where the configuration of networks create nodes that facilitate movement. Globally, the protection, conservation and restoration of such linear networks has an important influence on the persistence of biota within human-dominated landscapes.

Effects of coal-bed methane discharge waters on the vegetation and soil ecosystem in Powder River Basin, Wyoming

USGS Publications Warehouse

Stearns, M.; Tindall, J.A.; Cronin, G.; Friedel, M.J.; Bergquist, E.

2005-01-01

Coal-bed methane (CBM) co-produced discharge waters in the Powder River Basin of Wyoming, resulting from extraction of methane from coal seams, have become a priority for chemical, hydrological and biological research during the last few years. Soil and vegetation samples were taken from affected and reference sites (upland elevations and wetted gully) in Juniper Draw to investigate the effects of CBM discharge waters on soil physical and chemical properties and on native and introduced vegetation density and diversity. Results indicate an increase of salinity and sodicity within local soil ecosystems at sites directly exposed to CBM discharge waters. Elevated concentrations of sodium in the soil are correlated with consistent exposure to CBM waters. Clay-loam soils in the study area have a much larger specific surface area than the sandy soils and facilitate a greater sodium adsorption. However, there was no significant relation between increasing water sodium adsorption ratio (SAR) values and increasing sediment SAR values downstream; however, soils exposed to the CBM water ranged from the moderate to severe SAR hazard index. Native vegetation species density was highest at the reference (upland and gully) and CBM affected upland sites. The affected gully had the greatest percent composition of introduced vegetation species. Salt-tolerant species had the greatest richness at the affected gully, implying a potential threat of invasion and competition to established native vegetation. These findings suggest that CBM waters could affect agricultural production operations and long-term water quality. ?? Springer 2005.

Soil characteristics and plant exotic species invasions in the Grand Staircase-Escalante National Monument, Utah, USA

USGS Publications Warehouse

Bashkin, Michael A.; Stohlgren, Thomas J.; Otsuki, Yuka; Lee, Michelle; Evangelista, Paul H; Belnap, Jayne

2003-01-01

The Grand Staircase - Escalante National Monument (GSENM) contains a rich diversity of native plant communities. However, many exotic plant species have become established, potentially threatening native plant diversity. We sought to quantify patterns of native and exotic plant species and cryptobiotic crusts (mats of lichens, algae, and mosses on the soil surface), and to examine soil characteristics that may indicate or predict exotic species establishment and success. We established 97 modified-Whittaker vegetation plots in 11 vegetation types over a 29,000 ha area in the Monument. Canonical correspondence analysis (CCA) and multiple linear regressions were used to quantify relationships between soil characteristics and associated native and exotic plant species richness and cover. CCA showed that exotic species richness was significantly (P<0.05) associated with soil P (r=0.84), percentage bare ground (r=0.71), and elevation (r=0.67). Soil characteristics alone were able to predict 41 and 46% of the variation in exotic species richness and cover, respectively. In general, exotic species invasions tend to occur in fertile soils relatively high in C, N and P. These areas are represented by rare mesic high-elevation habitats that are rich in native plant diversity. This suggests that management should focus on the protection of the rare but important vegetation types with fertile soils.

Consequences of buffelgrass pasture development for primary productivity, perennial plant richness, and vegetation structure in the drylands of Sonora, Mexico.

PubMed

Franklin, Kimberly; Molina-Freaner, Francisco

2010-12-01

In large parts of northern Mexico native plant communities are being converted to non-native buffelgrass (Pennisetum ciliare) pastures, and this conversion could fundamentally alter primary productivity and species richness. In Sonora, Mexico land conversion is occurring at a regional scale along a rainfall-driven gradient of primary productivity, across which native plant communities transition from desert scrub to thorn scrub. We used a paired sampling design to compare a satellite-derived index of primary productivity, richness of perennial plant species, and canopy-height profiles of native plant communities with buffelgrass pastures. We sampled species richness across a gradient of primary productivity in desert scrub and thorn scrub vegetation to examine the influence of site productivity on the outcomes of land conversion. We also examined the influence of pasture age on species richness of perennial plants. Index values of primary productivity were lower in buffelgrass pastures than in native vegetation, which suggests a reduction in primary productivity. Land conversion reduced species richness by approximately 50% at local and regional scales, reduced tree and shrub cover by 78%, and reduced canopy height. Land conversion disproportionately reduced shrub species richness, which reflects the common practice among Sonoran ranchers of conserving certain tree and cactus species. Site productivity did not affect the outcomes of land conversion. The age of a buffelgrass pasture was unrelated to species richness within the pasture, which suggests that passive recovery of species richness to preconversion levels is unlikely. Our findings demonstrate that land conversion can result in large losses of plant species richness at local and regional scales and in substantial changes to primary productivity and vegetation structure, which casts doubt on the feasibility of restoring native plant communities without active intervention on the part of land managers. © 2010 Society for Conservation Biology.

Vegetation component of geothermal EIS studies: Introduced plants, ecosystem stability, and geothermal development

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

NONE

This paper contributes new information about the impacts from introduced plant invasions on the native Hawaiian vegetation as consequences of land disturbance and geothermal development activities. In this regard, most geothermal development is expected to act as another recurring source of physical disturbance which favors the spread and maintenance of introduced organisms throughout the region. Where geothermal exploration and development activities extend beyond existing agricultural and residential development, they will become the initial or sole source of disturbance to the naturalized vegetation of the area. Kilauea has a unique ecosystem adapted to the dynamics of a volcanically active landscape. Themore » characteristics of this ecosystem need to be realized in order to understand the major threats to the ecosystem and to evaluate the effects of and mitigation for geothermal development in Puna. The native Puna vegetation is well adapted to disturbances associated with volcanic eruption, but it is ill-adapted to compete with alien plant species in secondary disturbances produced by human activities. Introduced plant and animal species have become a major threat to the continued presence of the native biota in the Puna region of reference.« less

Disaster risk assessment case study: Recent drought on the Navajo Nation, USA

USGS Publications Warehouse

Hiza, Margaret; Kelley, Klara B.; Francis, Harris; Block, Debra

2011-01-01

The Navajo Nation is an ecologically sensitive semi-arid to arid section of the southern Colorado Plateau. In this remote part of the United States, located at the Four Corners (Arizona, New Mexico, Colorado, and Utah), traditional people live a subsistence lifestyle that is inextricably tied to, and dependent upon, landscape conditions and water supplies. Soft bedrock lithologies and sand dunes dominate the region, making it highly sensitive to fluctuations in precipitation intensity, percent vegetation cover, and local land use practices. However, this region has sparse and discontinuous meteorological monitoring records. As a complement to the scant long-term meteorological records and historical documentation, we conducted interviews with 50 Native American elders from the Navajo Nation and compiled their lifetime observations on the changes in water availability, weather, and sand or dust storms. We then used these observations to further refine our understanding of the historical trends and impacts of climate change and drought for the region. In addition to altered landscape conditions due to climatic change, drought, and varying land use practices over the last 130 years, the Navajo people have been affected by federal policies and harsh economic conditions which weaken their cultural fabric. We conclude that a long-term drying trend and decreasing snowpack, superimposed on regional drought cycles, will magnify drought impacts on the Navajo Nation and leave its people increasingly vulnerable.

Preliminary Analysis of AIS Spectral Data Acquired from Semi-arid Shrub Communities in the Owens Valley, California

NASA Technical Reports Server (NTRS)

Ustin, S. L.; Rock, B. N.

1985-01-01

Spectral characteristics of semic-arid plant communities using 128 channel airborne imaging spectrometer (AIS) data acquired on October 30, 1984. Both field and AIS spectra of vegetation were relatively featureless and differed from substrate spectra primarily in albedo. Unvegetated sand dunes were examined to assess spectral variation resulting from topographic irregularity. Although shrub cover as low as 10% could be detected on relatively flat surfaces, such differences were obscured in more heterogeneous terrain. Sagebrush-covered fans which had been scarred by fire were studied to determine the effect of changes in plant density on reflectance. Despite noise in the atmospherically corrected spectra, these provide better resolution of differences in plant density than spectra which are solar-corrected only. A high negative correlation was found between reflectance and plant cover in areas which had uniform substrates and vegetation types. A lower correlation was found where vegetation and substrates were more diverse.

The applicability of ERTS-1 data covering the major landforms of Kenya. [landforms, vegetation, soils, forests

NASA Technical Reports Server (NTRS)

Omino, J. H. O. (Principal Investigator)

1973-01-01

The author has identified the following significant results. Five investigators report on the applicability of ERTS-1 data covering the major landforms of Kenya. Deficiencies due to lack of equipment, repetitive coverage and interpretation know-how are also reported on. Revision of lake shorelines is an immediate benefit. Basement system metasediments are rapidly differentiated, but dune areas are not readily distinguishable from sandy soils. Forest, moorland, high altitude grass, tea, and conifer plantations are readily distinguished, with podocarpus forest especially distinguishable from podocarpus/juniperus forest. In the arid areas physiographic features, indicating the major soil types, are readily identified and mapped. Preliminary vegetation type analysis in the Mara Game Reserve indicates that in a typical savannah area about 36% of the vegetation types are distinguishable at a scale of 1:1 million as well as drainage patterns and terrain features.

Long-term analysis of the role of Traganum moquinii plants in the foredune formation of an arid dunefield (Maspalomas, Gran Canaria, Canary Islands).

NASA Astrophysics Data System (ADS)

García-Romero, Leví; Hernández-Cordero, Antonio; Hernández-Calvento, Luis; Hesp, Patrick A.

2017-04-01

In recent decades, important environmental changes have been detected in dune systems around the world. Vegetation on the foredune provides stability to the coastal dunefields, capturing and accumulating sediments, which is an important function among other ecosystem services. For this reason, vegetation has been used as an indicator when studying anthropogenic and natural processes in the foredunes, especially when an increase of the vulnerability has been detected. Foredunes of arid dunefields have been little studied. They present significant differences with respect to the foredune of other climatic zones. Traganum moquinii is the predominant plant species in the foredune of arid dunefields around the Canary Islands (including South Morocco, Mauritania and other close archipelagos, like Cape Verde). This bush species plays an important geomorphological role: its interaction with the aeolian sedimentary processes generates nebkhas, shadow dunes and arid parabolic shaped dunes. The objective of this work is to show the morphometric evolution of the foredune of an arid dunefield of the Canary Islands, Maspalomas (Gran Canaria), as well as explaining the function of Traganum moquinii on it. One morphometric variable (number of nebkhas) and six morphologic variables of Traganum moquinii species (density, mean distance between Traganum moquinii individuals, number of Traganum moquinii individuals in line one, mean diameter of Traganum moquinii individuals in line one, mean distance between Traganum moquinii individuals in line one, density Traganum moquinii individuals in line one) have been measured in ten observation plots, from the 1960s to the present, through detailed historical aerial photographs and orthophotos, using GIS. The morphometric changes have been identified, and the variables have been related from statistical analysis to detect the function exerted by Traganum moquinii species in the foredune. The change in the number of nebkhas enables the characterization of three types of foredune environments, which lie N-S. Measured variables in the first line of the foredune present significant relations with the number of nebkhas. The changes detected and the relationships observed between variables are related with natural processes and antrophogenic impacts. This information can be useful for arid coastal dune systems management, as well as restoration tasks in arid foredunes.

Contribution to the study of thermal properties of clay bricks reinforced by date palm fiber

NASA Astrophysics Data System (ADS)

Mekhermeche, A.; Kriker, A.; Dahmani, S.

2016-07-01

The Saharan regions of Algeria are characterized by a hot and dry climate. The most used cement materials such as theconcrete or the mortar blocks have bad thermal characteristic. However, these regions have several local materials: clay, dune sand and some natural fibers, which are formerly proved their thermal efficiency. The price of construction material used therefore depends on the international market constantly destabilized by theeconomic crisis coupled with the energy crisis in recent times. To produce a framework of life at a lower cost, it is important, therefore, to circumvent the influence of the cost of energy by upgrading the local materials of construction. In order to improve thermal performances in Saharan building materials this study was lanced. The aim of this research isthen to fabricate some bricks using three local materials: namely the clay, sand dune and the fibers of date palm. The percentage of sand and fibers varies from 0% to 40% and 0% to 3% by mass respectively. A sand dune of Ain El Beida of Ouargla of Algeria was used. Clay was extracted from Beldet Amer of Touggourt Ouargla Algérie. The fibers used in this study were vegetable fibers from date palm of Ouargla Algeria. The results showed that increasing in the mass fraction of sand and of fiber were beneficial for improving thermal properties. As function of increasing the percentage of sand dune and fibers there were: A decrease in: thermal conductivity, specific heat, heat capacity, thermal effusivity and thermal diffusivity and there were an increase in the thermal resistance.

Plant Succession on the Mount St. Helen's Debris-Avalanche Deposit and the Role of Non-native Species

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

Denton, Elsie M.; Dale, Virginia H.

The abstract is published online only. If you did not include a short abstract for the online version when you submitted the manuscript, the first paragraph or the first 10 lines of the chapter will be displayed here. If possible, please provide us with an informative abstract. The debris-avalanche deposit is one of the most disturbed areas created by the 1980 eruption of Mount St. Helens, with little survival of a few plant fragments and primary succession mostly being initiated by the seeds dispersed onto the newly emplaced material. Vegetation changes on the debris-avalanche deposit during the first 30 yearsmore » post eruption are analyzed considering the role of non-native species and potential future vegetation patterns on the deposit. We found that the aerial distribution of largely non-native seeds on a subset of plots at Mount St. Helens in 1980 has had a pronounced and enduring effect on subsequent vegetation communities.« less

MANAGEMENT OF SMALL MAMMALS IN A RELICT GRASSLAND IN CALIFORNIA'S CENTRAL VALLEY

Treesearch

ANNE POOPATANAPONG; DOUGLAS A. KELT

1999-01-01

land-use patterns over the past century. In California's Central Valley these changes have resulted in replacement of native grassland vegetation by non-native annual grasses. Jepson Prairie is a natural reserve that has been set aside to preserve native vernal pool and bunchgrass habitats. Jepson Prairie also provides habitat for several state and federally...

Ecological integrity of remnant montane forests along an urban gradient in the Sierra Nevada

Treesearch

K. E. Heckmann; P.N. Manley; M.D. Schlesinger

2008-01-01

Urban development typically has extensive and intensive effects on native ecosystems, including vegetation communities and their associated biota. Increasingly, urban planning strives to retain elements of native ecosystems to meet multiple social and ecological objectives. The ecological integrity of native forests in an urbanizing landscape is challenged by a myriad...

The Carolina Sandhills: Quaternary eolian sand sheets and dunes along the updip margin of the Atlantic Coastal Plain province, southeastern United States

USGS Publications Warehouse

Swezey, Christopher; Fitzwater, Bradley A.; Whittecar, G. Richard; Mahan, Shannon; Garrity, Christopher P.; Aleman Gonzalez, Wilma B.; Dobbs, Kerby M.

2016-01-01

The Carolina Sandhills is a physiographic region of the Atlantic Coastal Plain province in the southeastern United States. In Chesterfield County (South Carolina), the surficial sand of this region is the Pinehurst Formation, which is interpreted as eolian sand derived from the underlying Cretaceous Middendorf Formation. This sand has yielded three clusters of optically stimulated luminescence ages: (1) 75 to 37 thousand years ago (ka), coincident with growth of the Laurentide Ice Sheet; (2) 28 to 18 ka, coincident with the last glacial maximum (LGM); and (3) 12 to 6 ka, mostly coincident with the Younger Dryas through final collapse of the Laurentide Ice Sheet. Relict dune morphologies are consistent with winds from the west or northwest, coincident with modern and inferred LGM January wind directions. Sand sheets are more common than dunes because of effects of coarse grain size (mean range: 0.35–0.59 mm) and vegetation. The coarse grain size would have required LGM wind velocities of at least 4–6 m/sec, accounting for effects of colder air temperatures on eolian sand transport. The eolian interpretation of the Carolina Sandhills is consistent with other evidence for eolian activity in the southeastern United States during the last glaciation.

Mapping gullies, dunes, lava fields, and landslides via surface roughness

NASA Astrophysics Data System (ADS)

Korzeniowska, Karolina; Pfeifer, Norbert; Landtwing, Stephan

2018-01-01

Gully erosion is a widespread and significant process involved in soil and land degradation. Mapping gullies helps to quantify past, and anticipate future, soil losses. Digital terrain models offer promising data for automatically detecting and mapping gullies especially in vegetated areas, although methods vary widely measures of local terrain roughness are the most varied and debated among these methods. Rarely do studies test the performance of roughness metrics for mapping gullies, limiting their applicability to small training areas. To this end, we systematically explored how local terrain roughness derived from high-resolution Light Detection And Ranging (LiDAR) data can aid in the unsupervised detection of gullies over a large area. We also tested expanding this method for other landforms diagnostic of similarly abrupt land-surface changes, including lava fields, dunes, and landslides, as well as investigating the influence of different roughness thresholds, resolutions of kernels, and input data resolution, and comparing our method with previously published roughness algorithms. Our results show that total curvature is a suitable metric for recognising analysed gullies and lava fields from LiDAR data, with comparable success to that of more sophisticated roughness metrics. Tested dunes or landslides remain difficult to distinguish from the surrounding landscape, partly because they are not easily defined in terms of their topographic signature.

Assessing the geomorphological vulnerability of arid beach-dune systems.

PubMed

Peña-Alonso, Carolina; Gallego-Fernández, Juan B; Hernández-Calvento, Luis; Hernández-Cordero, Antonio I; Ariza, Eduard

2018-09-01

In this study, an arid dune vulnerability index (ADVI) is developed using a system of indicators to evaluate the geomorphological vulnerability of beach-dune systems of arid regions. The indicators are comprised of three analytical dimensions (susceptibility, exposure and resilience) and their corresponding sub-indices and variables and were assessed for eleven sites located in four aeolian sedimentary systems of the Canary archipelago (Spain). The selected sites have varying geomorphological characteristics, vegetation types, marine and wind conditions and human pressure degrees, and have seen different trends in their geomorphological evolution since 1960. The eleven sites were separated into three groups according to their different conservation status and different management needs, and the results of the ADVI dimensions and variables were compared and analyzed for these three groups. In general, the results obtained in the analyzed sites reveal that susceptibility and exposure dimensions are related to low-moderate values, while resilience was high. Only one site presented a state of critical vulnerability, due to the loss of its capacity to maintain its geomorphological function in recent decades. Given the lack of knowledge about geomorphological vulnerability processes in foredunes of arid regions, ADVI is the first approximation to geomorphological diagnostic in these environments and can be useful for managers. Copyright © 2018 Elsevier B.V. All rights reserved.

Home Range Use and Movement Patterns of Non-Native Feral Goats in a Tropical Island Montane Dry Landscape

PubMed Central

Chynoweth, Mark W.; Lepczyk, Christopher A.; Litton, Creighton M.; Hess, Steven C.; Kellner, James R.; Cordell, Susan

2015-01-01

Advances in wildlife telemetry and remote sensing technology facilitate studies of broad-scale movements of ungulates in relation to phenological shifts in vegetation. In tropical island dry landscapes, home range use and movements of non-native feral goats (Capra hircus) are largely unknown, yet this information is important to help guide the conservation and restoration of some of the world’s most critically endangered ecosystems. We hypothesized that feral goats would respond to resource pulses in vegetation by traveling to areas of recent green-up. To address this hypothesis, we fitted six male and seven female feral goats with Global Positioning System (GPS) collars equipped with an Argos satellite upload link to examine goat movements in relation to the plant phenology using the Normalized Difference Vegetation Index (NDVI). Movement patterns of 50% of males and 40% of females suggested conditional movement between non-overlapping home ranges throughout the year. A shift in NDVI values corresponded with movement between primary and secondary ranges of goats that exhibited long-distance movement, suggesting that vegetation phenology as captured by NDVI is a good indicator of the habitat and movement patterns of feral goats in tropical island dry landscapes. In the context of conservation and restoration of tropical island landscapes, the results of our study identify how non-native feral goats use resources across a broad landscape to sustain their populations and facilitate invasion of native plant communities. PMID:25807275

Home range use and movement patterns of non-native feral goats in a tropical island montane dry landscape.

PubMed

Chynoweth, Mark W; Lepczyk, Christopher A; Litton, Creighton M; Hess, Steven C; Kellner, James R; Cordell, Susan

2015-01-01

Advances in wildlife telemetry and remote sensing technology facilitate studies of broad-scale movements of ungulates in relation to phenological shifts in vegetation. In tropical island dry landscapes, home range use and movements of non-native feral goats (Capra hircus) are largely unknown, yet this information is important to help guide the conservation and restoration of some of the world's most critically endangered ecosystems. We hypothesized that feral goats would respond to resource pulses in vegetation by traveling to areas of recent green-up. To address this hypothesis, we fitted six male and seven female feral goats with Global Positioning System (GPS) collars equipped with an Argos satellite upload link to examine goat movements in relation to the plant phenology using the Normalized Difference Vegetation Index (NDVI). Movement patterns of 50% of males and 40% of females suggested conditional movement between non-overlapping home ranges throughout the year. A shift in NDVI values corresponded with movement between primary and secondary ranges of goats that exhibited long-distance movement, suggesting that vegetation phenology as captured by NDVI is a good indicator of the habitat and movement patterns of feral goats in tropical island dry landscapes. In the context of conservation and restoration of tropical island landscapes, the results of our study identify how non-native feral goats use resources across a broad landscape to sustain their populations and facilitate invasion of native plant communities.

Diets of insectivorous birds along the Colorado River in Grand Canyon, Arizona

USGS Publications Warehouse

Yard, H.K.; van Riper, Charles; Brown, B.T.; Kearsley, M.J.

2004-01-01

We examined diets of six insectivorous bird species (n = 202 individuals) from two vegetation zones along the Colorado River in Grand Canyon National Park, Arizona, 1994. All bird species consumed similar quantities of caterpillars and beetles, but use of other prey taxa varied. Non-native leafhoppers (Opsius stactagolus) specific to non-native tamarisk (Tamarix chinensis) substantially augmented Lucy's Warbler (Vermivora luciae) diets (49%), while ants comprised 82% of Yellow-breasted Chat (Icteria virens) diets. Yellow Warbler (Dendroica petechia) diets were composed of 45% aquatic midges. All bird species consumed the non-native leafhopper specific to tamarisk. Comparison of bird diets with availability of arthropod prey from aquatic and terrestrial origins showed terrestrial insects comprised 91% of all avian diets compared to 9% of prey from aquatic origin. Seasonal shifts in arthropod prey occurred in diets of three bird species, although no seasonal shifts were detected in arthropods sampled in vegetation indicating that at least three bird species were not selecting prey in proportion to its abundance. All bird species had higher prey overlap with arthropods collected in the native, mesquite-acacia vegetation zone which contained higher arthropod diversity and better prey items (i.e., Lepidoptera). Lucy's Warbler and Yellow Warbler consumed high proportions of prey items found in greatest abundance in the tamarisk-dominated vegetation zone that has been established since the construction of Glen Canyon Dam. These species appeared to exhibit ecological plasticity in response to an anthropogenic increase in prey resources.

Home range use and movement patterns of non-native feral goats in a tropical island montane dry landscape

USGS Publications Warehouse

Chynoweth, Mark W.; Lepczyk, Christopher A.; Litton, Creighton M.; Hess, Steve; Kellner, James; Cordell, Susan

2015-01-01

Advances in wildlife telemetry and remote sensing technology facilitate studies of broad-scale movements of ungulates in relation to phenological shifts in vegetation. In tropical island dry landscapes, home range use and movements of non-native feral goats (Capra hircus) are largely unknown, yet this information is important to help guide the conservation and restoration of some of the world’s most critically endangered ecosystems. We hypothesized that feral goats would respond to resource pulses in vegetation by traveling to areas of recent green-up. To address this hypothesis, we fitted six male and seven female feral goats with Global Positioning System (GPS) collars equipped with an Argos satellite upload link to examine goat movements in relation to the plant phenology using the Normalized Difference Vegetation Index (NDVI). Movement patterns of 50% of males and 40% of females suggested conditional movement between non-overlapping home ranges throughout the year. A shift in NDVI values corresponded with movement between primary and secondary ranges of goats that exhibited long-distance movement, suggesting that vegetation phenology as captured by NDVI is a good indicator of the habitat and movement patterns of feral goats in tropical island dry landscapes. In the context of conservation and restoration of tropical island landscapes, the results of our study identify how non-native feral goats use resources across a broad landscape to sustain their populations and facilitate invasion of native plant communities.

Direct and Indirect Influence of Non-Native Neighbours on Pollination and Fruit Production of a Native Plant.

PubMed

Montero-Castaño, Ana; Vilà, Montserrat

2015-01-01

Entomophilous non-native plants can directly affect the pollination and reproductive success of native plant species and also indirectly, by altering the composition and abundance of floral resources in the invaded community. Separating direct from indirect effects is critical for understanding the mechanisms underlying the impacts of non-native species on recipient communities. Our aims are: (a) to explore both the direct effect of the non-native Hedysarum coronarium and its indirect effect, mediated by the alteration of floral diversity, on the pollinator visitation rate and fructification of the native Leopoldia comosa and (b) to distinguish whether the effects of the non-native species were due to its floral display or to its vegetative interactions. We conducted field observations within a flower removal experimental setup (i.e. non-native species present, absent and with its inflorescences removed) at the neighbourhood scale. Our study illustrates the complexity of mechanisms involved in the impacts of non-native species on native species. Overall, Hedysarum increased pollinator visitation rates to Leopoldia target plants as a result of direct and indirect effects acting in the same direction. Due to its floral display, Hedysarum exerted a direct magnet effect attracting visits to native target plants, especially those made by the honeybee. Indirectly, Hedysarum also increased the visitation rate of native target plants. Due to the competition for resources mediated by its vegetative parts, it decreased floral diversity in the neighbourhoods, which was negatively related to the visitation rate to native target plants. Hedysarum overall also increased the fructification of Leopoldia target plants, even though such an increase was the result of other indirect effects compensating for the observed negative indirect effect mediated by the decrease of floral diversity.

Direct and Indirect Influence of Non-Native Neighbours on Pollination and Fruit Production of a Native Plant

PubMed Central

Montero-Castaño, Ana; Vilà, Montserrat

2015-01-01

Background Entomophilous non-native plants can directly affect the pollination and reproductive success of native plant species and also indirectly, by altering the composition and abundance of floral resources in the invaded community. Separating direct from indirect effects is critical for understanding the mechanisms underlying the impacts of non-native species on recipient communities. Objectives Our aims are: (a) to explore both the direct effect of the non-native Hedysarum coronarium and its indirect effect, mediated by the alteration of floral diversity, on the pollinator visitation rate and fructification of the native Leopoldia comosa and (b) to distinguish whether the effects of the non-native species were due to its floral display or to its vegetative interactions. Methods We conducted field observations within a flower removal experimental setup (i.e. non-native species present, absent and with its inflorescences removed) at the neighbourhood scale. Results Our study illustrates the complexity of mechanisms involved in the impacts of non-native species on native species. Overall, Hedysarum increased pollinator visitation rates to Leopoldia target plants as a result of direct and indirect effects acting in the same direction. Due to its floral display, Hedysarum exerted a direct magnet effect attracting visits to native target plants, especially those made by the honeybee. Indirectly, Hedysarum also increased the visitation rate of native target plants. Due to the competition for resources mediated by its vegetative parts, it decreased floral diversity in the neighbourhoods, which was negatively related to the visitation rate to native target plants. Hedysarum overall also increased the fructification of Leopoldia target plants, even though such an increase was the result of other indirect effects compensating for the observed negative indirect effect mediated by the decrease of floral diversity. PMID:26110630

Determination of erosion thresholds and aeolian dune stabilization mechanisms via robotic shear strength measurements

NASA Astrophysics Data System (ADS)

Qian, F.; Lee, D. B.; Bodek, S.; Roberts, S.; Topping, T. T.; Robele, Y.; Koditschek, D. E.; Jerolmack, D. J.

2017-12-01

Understanding the parameters that control the spatial variation in aeolian soil erodibility is crucial to the development of sediment transport models. Currently, in-situ measurements of erodibility are time consuming and lack robustness. In an attempt to remedy this issue, we perform field and laboratory tests to determine the suitability of a novel mechanical shear strength method to assess soil erodibility. These tests can be performed quickly ( 1 minute) by a semi-autonomous robot using its direct-drive leg, while environmental controls such as soil moisture and grain size are simultaneously characterized. The robot was deployed at White Sands National Monument to delineate and understand erodibility gradients at two different scales: (1) from dry dune crest to moist interdune (distance 10s m), where we determined that shear strength increases by a factor of three with increasing soil moisture; and (2) from barren barchan dunes to vegetated and crusted parabolics downwind (distance 5 km), where we found that shear strength was enhanced by a factor of two relative to loose sand. Interestingly, shear strength varied little from carbonate-crusted dune surfaces to bio-crust covered interdunes in the downwind parabolic region, indicating that varied surface crusts contribute similarly to erosion resistance. To isolate the control of soil moisture on erodibility, we performed laboratory experiments in a sandbox. These results verify that the observed increase in soil erodibility from barchan crest to interdune at White Sands is dominated by soil moisture, and the variation in parabolic dune and barchan interdune areas results from a combination of soil moisture, bio-activity, and crust development. This study highlights that spatial variation of soil erodibility in arid environments is large enough to significantly affect sediment transport, and that probing soil erodibility with a robot has the potential to improve our understanding of this multifaceted problem.

Analysis of beachgrass ecomorphodynamics and foredune morphology along US Pacific Northwest coastal sand dunes using a Bayesian network

NASA Astrophysics Data System (ADS)

Biel, R.; Hacker, S.; Ruggiero, P.

2016-12-01

Coastal dunes provide valuable infrastructure for mitigating flooding and erosion hazard exposure by dissipating wave energy. Although vegetation is essential for foredune establishment and growth by facilitating sand deposition and stabilization, few have examined how plant distribution and abundance relates to foredune morphology in the field. The US Pacific Northwest coastal dune system presents an excellent case study for examining ecomorphodynamic processes on sand dunes. It exhibits a diverse array of geomorphological conditions, including a range of dissipative to reflective beaches and highly varied foredune morphology. Ecologically, the region contains two invasive, dune-building beachgrasses of the same genus (Ammophila arenaria and A. breviligulata). To explore how geomorphological and ecological drivers alter foredune morphology, we used a Bayesian network to assess the role of nearshore bathymetry, sand supply (measured as shoreline change rate), and beachgrass species identity and density in determining foredune morphology. At a finer scale, we also examined whether beachgrass density and species identity altered sand accretion between 2012 and 2014 at multiple points across the foredune using a mixed model. Our Bayesian network analysis indicates that nearshore slope, shoreline change rate, beach width, and beachgrass density directly or indirectly affect foredune width, slope, and height. However, we observed no relationships between species identity and foredune morphology. When examining the finer-scale relationship between beachgrass density and sand accretion at points along the foredune, we found that sand accretion was correlated with beachgrass stem density in 2012, new stem growth between 2012 and 2014, beach width, and elevation. Moreover, A. arenaria accreted more sand than A. breviligulata on the foredune face, suggesting that subtle differences in beachgrass morphology or growth patterns may produce differing accretion patterns across the foredune. Both analyses indicate that beachgrass density alters foredune morphology. Although A. arenaria and A. breviligulata exhibit differing sand accretion patterns at points across the foredune face, it is unclear whether these fine-scale differences produce coarse-scale changes in foredune morphology.

Forest road sideslopes and soil conservation techniques

Treesearch

Johnny M. Grace

2000-01-01

Forest road sideslopes have been identified as one of the major sources of erosion losses from managed forest systems. Stabilization by vegetation has shown the greatest potential for mitigation of soil erosion on forest road sideslopes. Sediment and runoff production from a wood excelsior erosion mat, native species vegetative mix, and exotic species vegetative mix...

The Impact of Rainfall on Soil Moisture Dynamics in a Foggy Desert.

PubMed

Li, Bonan; Wang, Lixin; Kaseke, Kudzai F; Li, Lin; Seely, Mary K

2016-01-01

Soil moisture is a key variable in dryland ecosystems since it determines the occurrence and duration of vegetation water stress and affects the development of weather patterns including rainfall. However, the lack of ground observations of soil moisture and rainfall dynamics in many drylands has long been a major obstacle in understanding ecohydrological processes in these ecosystems. It is also uncertain to what extent rainfall controls soil moisture dynamics in fog dominated dryland systems. To this end, in this study, twelve to nineteen months' continuous daily records of rainfall and soil moisture (from January 2014 to August 2015) obtained from three sites (one sand dune site and two gravel plain sites) in the Namib Desert are reported. A process-based model simulating the stochastic soil moisture dynamics in water-limited systems was used to study the relationships between soil moisture and rainfall dynamics. Model sensitivity in response to different soil and vegetation parameters under diverse soil textures was also investigated. Our field observations showed that surface soil moisture dynamics generally follow rainfall patterns at the two gravel plain sites, whereas soil moisture dynamics in the sand dune site did not show a significant relationship with rainfall pattern. The modeling results suggested that most of the soil moisture dynamics can be simulated except the daily fluctuations, which may require a modification of the model structure to include non-rainfall components. Sensitivity analyses suggested that soil hygroscopic point (sh) and field capacity (sfc) were two main parameters controlling soil moisture output, though permanent wilting point (sw) was also very sensitive under the parameter setting of sand dune (Gobabeb) and gravel plain (Kleinberg). Overall, the modeling results were not sensitive to the parameters in non-bounded group (e.g., soil hydraulic conductivity (Ks) and soil porosity (n)). Field observations, stochastic modeling results as well as sensitivity analyses provide soil moisture baseline information for future monitoring and the prediction of soil moisture patterns in the Namib Desert.

The Impact of Rainfall on Soil Moisture Dynamics in a Foggy Desert

PubMed Central

Li, Bonan; Wang, Lixin; Kaseke, Kudzai F.; Li, Lin; Seely, Mary K.

2016-01-01

Soil moisture is a key variable in dryland ecosystems since it determines the occurrence and duration of vegetation water stress and affects the development of weather patterns including rainfall. However, the lack of ground observations of soil moisture and rainfall dynamics in many drylands has long been a major obstacle in understanding ecohydrological processes in these ecosystems. It is also uncertain to what extent rainfall controls soil moisture dynamics in fog dominated dryland systems. To this end, in this study, twelve to nineteen months’ continuous daily records of rainfall and soil moisture (from January 2014 to August 2015) obtained from three sites (one sand dune site and two gravel plain sites) in the Namib Desert are reported. A process-based model simulating the stochastic soil moisture dynamics in water-limited systems was used to study the relationships between soil moisture and rainfall dynamics. Model sensitivity in response to different soil and vegetation parameters under diverse soil textures was also investigated. Our field observations showed that surface soil moisture dynamics generally follow rainfall patterns at the two gravel plain sites, whereas soil moisture dynamics in the sand dune site did not show a significant relationship with rainfall pattern. The modeling results suggested that most of the soil moisture dynamics can be simulated except the daily fluctuations, which may require a modification of the model structure to include non-rainfall components. Sensitivity analyses suggested that soil hygroscopic point (sh) and field capacity (sfc) were two main parameters controlling soil moisture output, though permanent wilting point (sw) was also very sensitive under the parameter setting of sand dune (Gobabeb) and gravel plain (Kleinberg). Overall, the modeling results were not sensitive to the parameters in non-bounded group (e.g., soil hydraulic conductivity (Ks) and soil porosity (n)). Field observations, stochastic modeling results as well as sensitivity analyses provide soil moisture baseline information for future monitoring and the prediction of soil moisture patterns in the Namib Desert. PMID:27764203

Long-term effects of seeding after wildfire on vegetation in Great Basin shrubland ecosystems

USGS Publications Warehouse

Knutson, Kevin C.; Pyke, David A.; Wirth, Troy A.; Arkle, Robert S.; Pilliod, David S.; Brooks, Matthew L.; Chambers, Jeanne C.; Grace, James B.

2014-01-01

1. Invasive annual grasses alter fire regimes in shrubland ecosystems of the western USA, threatening ecosystem function and fragmenting habitats necessary for shrub-obligate species such as greater sage-grouse. Post-fire stabilization and rehabilitation treatments have been administered to stabilize soils, reduce invasive species spread and restore or establish sustainable ecosystems in which native species are well represented. Long-term effectiveness of these treatments has rarely been evaluated. 2. We studied vegetation at 88 sites where aerial or drill seeding was implemented following fires between 1990 and 2003 in Great Basin (USA) shrublands. We examined sites on loamy soils that burned only once since 1970 to eliminate confounding effects of recurrent fire and to assess soils most conducive to establishment of seeded species. We evaluated whether seeding provided greater cover of perennial seeded species than burned–unseeded and unburned–unseeded sites, while also accounting for environmental variation. 3. Post-fire seeding of native perennial grasses generally did not increase cover relative to burned–unseeded areas. Native perennial grass cover did, however, increase after drill seeding when competitive non-natives were not included in mixes. Seeding non-native perennial grasses and the shrub Bassia prostrata resulted in more vegetative cover in aerial and drill seeding, with non-native perennial grass cover increasing with annual precipitation. Seeding native shrubs, particularly Artemisia tridentata, did not increase shrub cover or density in burned areas. Cover of undesirable, non-native annual grasses was lower in drill seeded relative to unseeded areas, but only at higher elevations. 4. Synthesis and applications. Management objectives are more likely to be met in high-elevation or precipitation locations where establishment of perennial grasses occurred. On lower and drier sites, management objectives are unlikely to be met with seeding alone. Intensive restoration methods such as invasive plant control and/or repeated sowings after establishment failures due to weather may be required in subsequent years. Managers might consider using native-only seed mixtures when establishment of native perennial grasses is the goal. Post-fire rehabilitation provides a land treatment example where long-term monitoring can inform adaptive management decisions to meet future objectives, particularly in arid landscapes where recovery is slow.

Non-native species impacts on pond occupancy by an anuran

USGS Publications Warehouse

Adams, Michael J.; Pearl, Christopher A.; Galvan, Stephanie; McCreary, Brome

2011-01-01

Non-native fish and bullfrogs (Lithobates catesbeianus; Rana catesbeiana) are frequently cited as factors contributing to the decline of ranid frogs in the western United States (Bradford 2005). This hypothesis is supported by studies showing competition with or predation by these introduced species (Kupferberg 1997, Kiesecker and Blaustein 1998, Lawler et al. 1999, Knapp et al. 2001) and studies suggesting a deficit of native frogs at sites occupied by bullfrogs or game fish (Hammerson 1982, Schwalbe and Rosen 1988, Fisher and Shaffer 1996, Adams 1999). Conversely, other studies failed to find a negative association between native ranids and bullfrogs and point out that presence of non-native species correlates with habitat alterations that could also contribute to declines of native species (Hayes and Jennings 1986; Adams 1999, 2000; Pearl et al. 2005). A criticism of these studies is that they may not detect an effect of non-native species if the process of displacement is at an early stage. We are not aware of any studies that have monitored a set of native frog populations to determine if non-native species predict population losses. Our objective was to study site occupancy trends in relation to non-native species for northern red-legged frogs (Rana aurora) on federal lands in the southern Willamette Valley, Oregon. We conducted a 5-yr monitoring study to answer the following questions about the status and trends of the northern red-legged frog: 1) What is the rate of local extinction (how often is a site that is occupied in year t unoccupied in year t+1) and what factors predict variation in local extinction? and 2) What is the rate of colonization (how often is a site that is unoccupied in year t occupied in year t+1) and what factors predict variation in colonization? The factors we hypothesized for local extinction were: 1) bullfrog presence, 2) bullfrogs mediated by wetland vegetation, 3) non-native fish (Centrarchidae), 4) non-native fish mediated by wetland vegetation, 5) extent of emergent vegetation, 6) extent of riparian forest, and 7) a combined effect of bullfrogs and fish. The factors that we hypothesized for colonization were: 1) the extent of human influence in the surrounding landscape, 2) riparian forest, and 3) wetland size.

Attacking invasive grasses

USGS Publications Warehouse

Keeley, Jon E.

2015-01-01

In grasslands fire may play a role in the plant invasion process, both by creating disturbances that potentially favour non-native invasions and as a possible tool for controlling alien invasions. Havill et al. (Applied Vegetation Science, 18, 2015, this issue) determine how native and non-native species respond to different fire regimes as a first step in understanding the potential control of invasive grasses.

Factors influencing non-native tree species distribution in urban landscapes

Treesearch

Wayne C. Zipperer

2010-01-01

Non-native species are presumed to be pervasive across the urban landscape. Yet, we actually know very little about their actual distribution. For this study, vegetation plot data from Syracuse, NY and Baltimore, MD were used to examine non-native tree species distribution in urban landscapes. Data were collected from remnant and emergent forest patches on upland sites...

Vegetation assessment of forests of Pagan Island, Commonwealth of the Northern Mariana Islands

USGS Publications Warehouse

Pratt, Linda W.

2011-01-01

During vegetation surveys in June–July 2010, 215 vascular plant species were observed on Pagan; 21 new island records of alien plants and 12 new island records of native plants were documented. Many of the new and recently sighted alien plants of the northern section of the island appeared to be in the incipient stage of invasion. Most of the new native plant sightings and a number of other rare tree and shrub species of Pagan were limited to forests of the rugged southern half of the island.

Establishing native vegetation and improved invasive species control on North Carolina roadsides.

DOT National Transportation Integrated Search

2011-10-20

"Field, greenhouse, and laboratory studies were conducted to evaluate the feasibility for the use of native warm season grasses (NWSGs) on North Carolina roadsides. Location, equipment, and multiple grass species were assessed to determine the ideal ...

Volunteer revegetation of waste rock surfaces at the Bingham Canyon Mine, Utah.

PubMed

Borden, Richard K; Black, Rick

2005-01-01

Voluntary recolonization of sulfide-bearing waste rock dumps by native vegetation is inhibited by the harsh chemical and physical conditions. The success of volunteer vegetation on the waste rock surfaces at the Bingham Canyon (Utah) porphyry copper deposit is most strongly dependent on the soil pH and salinity, and to a lesser extent on physical characteristics such as compaction and distance from seed source. Vegetation cover and richness both decline below a paste pH of about 6 and above a paste conductivity of about 0.7 dS/m (for a 1:1 soil to water mixture). No significant vegetation establishment occurs below a soil pH of about 4.5. Young sulfide-bearing waste rock surfaces at Bingham Canyon have high salinity, but as reactive pyrite is depleted and salts are flushed from the soil, the salinity eventually declines, allowing volunteer native vegetation to become established on surfaces with a circumneutral pH. Under natural conditions, the pH of older acidic weathered surfaces will recover very slowly, but it can be rapidly raised by adding relatively small amounts of limestone because there are few intact reactive sulfides. For uncompacted waste rock surfaces with favorable chemical conditions, less than 90% gravel content, and that are located near a native seed source, the arithmetic mean volunteer vegetation cover was 56 +/- 24% and the mean species richness was 17 +/- 5. These data indicate that with adequate surface preparation and limestone addition, direct planting of older, acidic, but low salinity waste rock surfaces can greatly accelerate natural revegetation.

Exotic plant species invade hot spots of native plant diversity

USGS Publications Warehouse

Stohlgren, T.J.; Binkley, Dan; Chong, G.W.; Kalkhan, M.A.; Schell, L.D.; Bull, K.A.; Otsuki, Yuka; Newman, G.; Bashkin, Michael A.; Son, Y.

1999-01-01

Some theories and experimental studies suggest that areas of low plant species richness may be invaded more easily than areas of high plant species richness. We gathered nested-scale vegetation data on plant species richness, foliar cover, and frequency from 200 1-m2 subplots (20 1000-m2 modified-Whittaker plots) in the Colorado Rockies (USA), and 160 1-m2 subplots (16 1000-m2 plots) in the Central Grasslands in Colorado, Wyoming, South Dakota, and Minnesota (USA) to test the generality of this paradigm.At the 1-m2 scale, the paradigm was supported in four prairie types in the Central Grasslands, where exotic species richness declined with increasing plant species richness and cover. At the 1-m2 scale, five forest and meadow vegetation types in the Colorado Rockies contradicted the paradigm; exotic species richness increased with native-plant species richness and foliar cover. At the 1000-m2 plot scale (among vegetation types), 83% of the variance in exotic species richness in the Central Grasslands was explained by the total percentage of nitrogen in the soil and the cover of native plant species. In the Colorado Rockies, 69% of the variance in exotic species richness in 1000-m2 plots was explained by the number of native plant species and the total percentage of soil carbon.At landscape and biome scales, exotic species primarily invaded areas of high species richness in the four Central Grasslands sites and in the five Colorado Rockies vegetation types. For the nine vegetation types in both biomes, exotic species cover was positively correlated with mean foliar cover, mean soil percentage N, and the total number of exotic species. These patterns of invasibility depend on spatial scale, biome and vegetation type, spatial autocorrelation effects, availability of resources, and species-specific responses to grazing and other disturbances. We conclude that: (1) sites high in herbaceous foliar cover and soil fertility, and hot spots of plant diversity (and biodiversity), are invasible in many landscapes; and (2) this pattern may be more closely related to the degree resources are available in native plant communities, independent of species richness. Exotic plant invasions in rare habitats and distinctive plant communities pose a significant challenge to land managers and conservation biologists.

The effects of black-tailed prairie dogs on plant communities within a complex urban landscape: an ecological surprise?

PubMed

Beals, Stower C; Hartley, Laurel M; Prevéy, Janet S; Seastedt, Timothy R

2014-05-01

Historically, prairie dogs (Cynomys spp.) have been considered essential keystone species of western United States grassland ecosystems because they provide unique services and increase vegetation community richness, evenness, and diversity. However, the effects of black-tailed prairie dogs (Cynomys ludovicianus) on lands adjacent to or surrounded by urban areas may not result in the same ecosystem benefits historically associated with their presence. An urban landscape presents prairie dogs with movement challenges unparalleled in natural landscapes, as well as suites of nonnative plant species that are more common in disturbed areas. This study examined a complex ecosystem where vegetation communities are being influenced by directional environmental change, and quantified the synergistic effects resulting from the protective management of a native keystone species. The data set for this analysis was comprised of 71 paired (occupied by prairie dogs vs. unoccupied) vegetation surveys and 156 additional unpaired surveys collected from around the city of Boulder, Colorado, USA for 14 yr. Linear mixed models were used to compare data from transects occupied and unoccupied by prairie dogs, as well as to evaluate the effect of prairie dog occupation duration. In the absence of prairie dogs, vegetation in this region exhibited declines in native grasses, no changes in introduced grasses, and increases in native and nonnative forbs and bare soil over the study interval. In the presence of prairie dogs, these observed directional changes were nearly all amplified at rates four to 10 times greater than when prairie dogs were absent. Areas in Boulder occupied by prairie dogs also had significantly lower richness, evenness, and diversity of plant species, compared to unoccupied areas. Analysis of plant functional groups revealed the significant reduction of perennial native grasses, as well as a significantly higher cover of introduced forbs in occupied areas. Prairie dogs amplified the effects of low-impact environmental directional changes, creating more novel vegetation communities than the environmental factors alone. Results from this research provide insight regarding the synergistic effects of a native keystone species within a complex human-impacted 21st century landscape.

Restoration Effects of the Riparian Forest on the Intertidal Fish Fauna in an Urban Area of the Amazon River

PubMed Central

Ferrari, Stephen F.; Vasconcelos, Huann C. G.; Mendes-Junior, Raimundo N. G.; Araújo, Andrea S.; Costa-Campos, Carlos Eduardo; Nascimento, Walace S.; Isaac, Victoria J.

2016-01-01

Urbanization causes environmental impacts that threaten the health of aquatic communities and alter their recovery patterns. In this study, we evaluated the diversity of intertidal fish in six areas affected by urbanization (areas with native vegetation, deforested areas, and areas in process of restoration of vegetation) along an urban waterfront in the Amazon River. 20 species were identified, representing 17 genera, 14 families, and 8 orders. The different degrees of habitat degradation had a major effect on the composition of the fish fauna; the two least affected sectors were the only ones in that all 20 species were found. Eight species were recorded in the most degraded areas. The analysis revealed two well-defined groups, coinciding with the sectors in better ecological quality and degraded areas, respectively. The native vegetation has been identified as the crucial factor to the recovery and homeostasis of the studied ecosystem, justifying its legal protection and its use in the restoration and conservation of altered and threatened environments. These results reinforce the importance of maintaining the native vegetation as well as its restoration in order to benefit of the fish populations in intertidal zones impacted by alterations resulting from inadequate urbanization. PMID:27699201

The effect of leaf beetle herbivory on the fire behaviour of tamarisk (Tamarix ramosissima Lebed.)

USGS Publications Warehouse

Drus, Gail M.; Dudley, Tom L.; Brooks, Matthew L.; Matchett, John R.

2012-01-01

The non-native tree, Tamarix spp. has invaded desert riparian ecosystems in the south-western United States. Fire hazard has increased, as typically fire-resistant native vegetation is replaced by Tamarix. The tamarisk leaf beetle, Diorhabda carinulata Desbrochers, introduced for biological control, may affect fire behaviour by converting hydrated live Tamarix leaves and twigs into desiccated and dead fuels. This potentially increases fire hazard in the short term before native vegetation can be re-established. This study investigates how fire behaviour is altered in Tamarix fuels desiccated by Diorhabda herbivory at a Great Basin site, and by herbivory simulated by foliar herbicide at a Mojave Desert site. It also evaluates the influence of litter depth on fire intensity. Fire behaviour was measured with a fire intensity index that integrates temperature and duration (degree-minutes above 70°C), and with maximum temperature, duration, flame lengths, rates of spread and vegetation removal. Maximum temperature, flame length and rate of spread were enhanced by foliar desiccation of Tamarix at both sites. At only the Mojave site, there was a trend for desiccated trees to burn with greater fire intensity. At both sites, fire behaviour parameters were influenced to a greater degree by litter depth, vegetation density and drier and windier conditions than by foliar desiccation.

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

PubMed

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

2009-05-01

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

Vegetation study in support of the design and optimization of vegetative soil covers, Sandia National Laboratories, Albuquerque, New Mexico.

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

Peace, Gerald; Goering, Timothy James; Knight, Paul J.

A vegetation study was conducted in Technical Area 3 at Sandia National Laboratories, Albuquerque, New Mexico in 2003 to assist in the design and optimization of vegetative soil covers for hazardous, radioactive, and mixed waste landfills at Sandia National Laboratories/New Mexico and Kirtland Air Force Base. The objective of the study was to obtain site-specific, vegetative input parameters for the one-dimensional code UNSAT-H and to identify suitable, diverse native plant species for use on vegetative soil covers that will persist indefinitely as a climax ecological community with little or no maintenance. The identification and selection of appropriate native plant speciesmore » is critical to the proper design and long-term performance of vegetative soil covers. Major emphasis was placed on the acquisition of representative, site-specific vegetation data. Vegetative input parameters measured in the field during this study include root depth, root length density, and percent bare area. Site-specific leaf area index was not obtained in the area because there was no suitable platform to measure leaf area during the 2003 growing season due to severe drought that has persisted in New Mexico since 1999. Regional LAI data was obtained from two unique desert biomes in New Mexico, Sevilletta Wildlife Refuge and Jornada Research Station.« less

Effects of an invasive plant on a desert sand dune landscape

USGS Publications Warehouse

Barrows, C.W.; Allen, E.B.; Brooks, M.L.; Allen, M.F.

2009-01-01

Given the abundance of non-native species invading wildland habitats, managers need to employ informed triage to focus control efforts on weeds with the greatest potential for negative impacts. Our objective here was to determine the level of threat Sahara mustard, Brassica tournefortii, represents to meeting regional goals for protecting biodiversity. Sahara mustard has spread throughout much of the Mojave and lower Sonoran Deserts. It has occurred in southern California's Coachella Valley for nearly 80 years, punctuated by years of extremely high abundance following high rainfall. In those years the mustard has clear negative impacts on the native flora. Using mustard removal experiments we identified reductions in native plant reproduction, shifting composition increasingly toward Sahara mustard while decreasing the fraction of native species. High between-year variance in precipitation may be a key to maintaining biodiversity as the mustard is less abundant in drier years. Sahara mustard impacts to the native fauna were much less evident. Of the animal species evaluated, only the Coachella Valley fringe-toed lizard, Uma inornata, demonstrated a negative response to mustard abundance; however the impacts were short-lived, lasting no more than a year after the mustard's dominance waned. Without control measures the long-term impacts to desert biodiversity may rest on the changing climate. Wetter conditions or increased periodicity of high rainfall years will favor Sahara mustard and result in reduced biodiversity, especially of native annual plants. Drier conditions will keep the mustard from becoming dominant but may have other negative consequences on the native flora and fauna. ?? 2008 Springer Science+Business Media B.V.

Effects of space shuttle launches STS-1 through STS-9 on terrestrial vegetation of John F. Kennedy Space Center, Florida

NASA Technical Reports Server (NTRS)

Schmalzer, P. A.; Hinkle, C. R.; Breininger, D.; Knott, W. M., III (Editor); Koller, A. M., Jr. (Editor)

1985-01-01

Space Shuttle launches produce a cloud containing hydrochloric acid (HCl), aluminum oxide (Al203), and other substances. Acidities of less than 0.5 pH have been measured routinely in association with the launch cloud. In an area of about 22 ha regularly exposed to the exhaust cloud during most Shuttle launches, acute vegetation damage has resulted from the first nine Shuttle launches. Changes include loss of sensitive species, loss of plant community structure, reduction in total cover, and replacement of some species by weedy invaders. Community level changes define a retrogressive sequence. One-time impacts to strand and dune vegetation occurred after launches of STS-8 and STS-9. Acute vegetation damage occurred especially to sensitive species. Within six months, however, recovery was nearly complete. Sensitivity of species to the launch cloud was partially predicted by previous laboratory studies. Far-field acidic and dry fallout from the cloud as it rises to stabilization and moves with the prevailing winds causes vegetation spotting. Damage from this deposition is minor; typically at most 1% to 5% of leaf surface area is affected. No plant mortality or community changes have occurred from far-field deposition.

Ecological restoration and recovery in the wind-blown sand hazard areas of northern China: relationship between soil water and carrying capacity for vegetation in the Tengger Desert.

PubMed

Li, XingRong; Zhang, ZhiShan; Tan, HuiJuan; Gao, YanHong; Liu, LiChao; Wang, XingPing

2014-05-01

The main prevention and control area for wind-blown sand hazards in northern China is about 320000 km(2) in size and includes sandlands to the east of the Helan Mountain and sandy deserts and desert-steppe transitional regions to the west of the Helan Mountain. Vegetation recovery and restoration is an important and effective approach for constraining wind-blown sand hazards in these areas. After more than 50 years of long-term ecological studies in the Shapotou region of the Tengger Desert, we found that revegetation changed the hydrological processes of the original sand dune system through the utilization and space-time redistribution of soil water. The spatiotemporal dynamics of soil water was significantly related to the dynamics of the replanted vegetation for a given regional precipitation condition. The long-term changes in hydrological processes in desert areas also drive replanted vegetation succession. The soil water carrying capacity of vegetation and the model for sand fixation by revegetation in aeolian desert areas where precipitation levels are less than 200 mm are also discussed.

Do traits of invasive species influence decomposition and soil respiration of disturbed ecosystems?

NASA Astrophysics Data System (ADS)

Wells, A. J.; Balster, N. J.

2009-12-01

Large-scale landscape disturbances typically alter the terrestrial carbon cycle leading to shifts in pools of soil carbon. Restoration of disturbed landscapes with prairie vegetation has thus been practiced with the intent of increasing carbon accrual in soils. However, since disturbed soils are prone to invasion by non-native invasive species, many ecological restorations have resulted in unexpected outcomes, which may be explained by differences in plant traits such as tissue quality and biomass allocation. Typically, the tissue of invasive species has lower C:N ratios relative to native species, and consequently, faster decomposition rates, which potentially can alter the balance in soil carbon. The primary objective of this research was to compare the effects of native prairie species versus non-native invasive species on the carbon cycling within a novel environment: a recently dewatered basin in southwestern Wisconsin following dam removal. We hypothesized that a higher invasive to native species ratio would result in faster litter decomposition and a higher rate of soil respiration. To test this hypothesis, we seeded newly exposed sediments with native prairie seeds in 2005, annually collected aboveground plant biomass (by species per plot), calculated decomposition rate of native and invasive litter (underneath both canopy types), and measured soil respiration during the growing season of 2009. After four years of seeding, the aboveground biomass of the native vegetation has increased significantly (p < 0.01) from 14.4 to 351 g m-2 while invasive species biomass has decreased from 459 to 296 g m-2. Senesced tissue from mixed native species had a higher C:N ratio, 27:1 (43% C: 1.6% N), than tissue from mixed invasive species, 24:1 (35% C: 1.5% N). However, after 7 months, we found that the rate of decomposition depended on both litter type and plant canopy type (p < 0.01); invasive plant tissue had a slightly faster decomposition rate than the native litter and this rate was elevated under invasive species. Mean soil respiration rates ranged from 4.1 to 7.7 µmol C m-2 s-1. Our preliminary results suggest that respiration increases exponentially with soil temperature, as soil temperature explained 20% of the variation in soil respiration. However, the vegetation type did not have a significant effect on the respiration rate. Our results suggest that vegetation traits may be influencing the cycling of carbon at this site, but that spatial variation in abiotic conditions above and belowground appear to control decomposition and soil respiration at a local scale. Moreover, the ecophysiological interactions measured here may have practical implications on the restoration of disturbed ecosystems and the manner in which invasive species are viewed relative to the accrual soil carbon.

Shade treatment affects structure and recovery of invasive C4 African grass Echinochloa pyramidalis.

PubMed

López Rosas, Hugo; Moreno-Casasola, Patricia; Espejel González, Verónica E

2015-03-01

Echinochloa pyramidalis (Lam.) Hitchc. & Chase is an African grass with C4 photosynthesis, high biomass production, and high vegetative propagation that is tolerant to grazing and able to grow in flooded and dry conditions. Thus, it is highly invasive in tropical freshwater marshes where it is intentionally planted by ranchers to increase cattle production. This invasion is reducing plant biodiversity by increasing the invader's aerial coverage, changing wetland hydrology and causing soil physicochemical changes such as vertical accretion. Reducing the dominance of this species and increasing the density of native wetland species is a difficult, expensive, and time-consuming process. We applied a series of disturbance treatments aimed at eliminating E. pyramidalis and recovering the native vegetation of a partially invaded freshwater marsh. Treatments included physical (cutting, soil disking, transplanting individuals of the key native species Sagittaria lancifolia subsp. media (Micheli) Bogin, and/or reducing light with shade mesh) and/or chemical (spraying Round-Up™ herbicide) disturbances. At the end of the experiment, four of the five treatments used were effective in increasing the cover and biomass of native species and reducing that of E. pyramidalis. The combination of these treatments should be used to generate a proposal for the restoration of tropical wetlands invaded by non-native grasses. A promising treatment is using soil disked to soften the soil and destroy belowground structures such as roots and rhizomes. This treatment would be more promising if combined with the use of shade cloth. If it is desirable not to impact the soil or if there is not enough budget to make an effort to include active restoration disking soil, the use of shade cloth will suffice, although the recovery of native vegetation will be slower.

Shade treatment affects structure and recovery of invasive C4 African grass Echinochloa pyramidalis

PubMed Central

López Rosas, Hugo; Moreno-Casasola, Patricia; Espejel González, Verónica E

2015-01-01

Echinochloa pyramidalis (Lam.) Hitchc. & Chase is an African grass with C4 photosynthesis, high biomass production, and high vegetative propagation that is tolerant to grazing and able to grow in flooded and dry conditions. Thus, it is highly invasive in tropical freshwater marshes where it is intentionally planted by ranchers to increase cattle production. This invasion is reducing plant biodiversity by increasing the invader's aerial coverage, changing wetland hydrology and causing soil physicochemical changes such as vertical accretion. Reducing the dominance of this species and increasing the density of native wetland species is a difficult, expensive, and time-consuming process. We applied a series of disturbance treatments aimed at eliminating E. pyramidalis and recovering the native vegetation of a partially invaded freshwater marsh. Treatments included physical (cutting, soil disking, transplanting individuals of the key native species Sagittaria lancifolia subsp. media (Micheli) Bogin, and/or reducing light with shade mesh) and/or chemical (spraying Round-Up™ herbicide) disturbances. At the end of the experiment, four of the five treatments used were effective in increasing the cover and biomass of native species and reducing that of E. pyramidalis. The combination of these treatments should be used to generate a proposal for the restoration of tropical wetlands invaded by non-native grasses. A promising treatment is using soil disked to soften the soil and destroy belowground structures such as roots and rhizomes. This treatment would be more promising if combined with the use of shade cloth. If it is desirable not to impact the soil or if there is not enough budget to make an effort to include active restoration disking soil, the use of shade cloth will suffice, although the recovery of native vegetation will be slower. PMID:25859337

Reclamation of skid roads with fiber mats and native vegetation: effects on erosion

Treesearch

shawn T. Grushecky; David w. McGill; William Grafton; John Edwards; Lisa Tager

2007-01-01

A research study was established to test the effectiveness of fiber mats and native seed mixtures in reducing soil erosion from newly-constructed skid roads in the Elk River Watershed in central West Virginia. Twelve road sections of equal grade were paired with a randomly-selected section receiving a fiber mat and native grass seed while the other road section was not...

Can thinning of overstory trees and planting of native tree saplings increase the establishment of native trees in exotic acacia plantations in south china?

Treesearch

SF Yuan; H Ren; N Liu; J Wang; QF Guo

2013-01-01

Assessing the effect of thinning of overstorey trees and planting of native trees will be helpful to better understand the vegetation restoration. A stand conversion experiment was conducted in a 12-year-old Acacia auriculiformis plantation in 1996. Treatments were thinning and underplanting, underplanting, thinning, and control. Results showed that...

Mystery #17 Answer

Atmospheric Science Data Center

2013-04-22

... and the region was dry until after mid-summer. 3.   Agriculture in this region is devoted primarily to vegetable and fruit ... native vegetation of the Pampas has been replaced by modern agriculture and cattle ranching, there were no forests in the Pampas 500 years ...

Bioindicator beetles and plants in desertified and eroded lands in Turkey

USDA-ARS?s Scientific Manuscript database

Xerophilous vegetation with characteristic insect assemblages is described in main agricultural regions and native landscapes of Turkey. Long term, intensive investigations documented vast biotic degradation of soil and vegetation (commonly referred to as desertification) by an overgrazing, construc...

Earth Observations taken by the Expedition 17 Crew

NASA Image and Video Library

2008-08-19

ISS017-E-013789 (19 Aug. 2008) --- Desert erosion in Libya is featured in this image photographed by an Expedition 17 crewmember on the International Space Station. This detailed view (covering 13 kilometers) shows the classic patterns of an erosional desert landscape located 300 kilometers south of Libya's Mediterranean coast. Widespread indented patterns are low escarpments and stream terraces generated by stream erosion -- on those few occasions in any decade when enough rain falls for streams to flow. The only areas with active sediment deposition are the stream beds which appear in this image as sinuous zones with a distinct component of black minerals, resulting in a darker coloration than adjacent low escarpments. Sediment is transported into the area from a volcanic landscape immediately upstream to the west. Other stream-generated features are several relict stream banks, one of which even shows both of the original parallel banks. According to scientists, the ancient stream banks are preserved from erosion by various hardening cements (mainly calcium carbonate and gypsum) introduced by the streams when they were active, probably during wetter climates in the past two million years. Relict stream courses show prior positions of streams, and also provide Earth analogs for similar features on Mars. The lack of vegetation is the first indication of the great aridity of the region, but sand dunes also appear as sinuous lines oriented perpendicular to the dominant northeasterly wind direction (transverse dunes). Assuming the dominant wind direction remains the same, these transverse dunes are expected to move further to the southwest over time. Some of the dunes cross the river courses, showing how seldom the river flows.

Genetic differentiation in life history traits and thermal stress performance across a heterogeneous dune landscape in Arabidopsis lyrata.

PubMed

Wos, Guillaume; Willi, Yvonne

2018-05-26

Over very short spatial scales, the habitat of a species can differ in multiple abiotic and biotic factors. These factors may impose natural selection on several traits and can cause genetic differentiation within a population. We studied multivariate genetic differentiation in a plant species of a sand dune landscape by linking environmental variation with differences in genotypic trait values and gene expression levels to find traits and candidate genes of microgeographical adaptation. Maternal seed families of Arabidopsis lyrata were collected in Saugatuck Dunes State Park, Michigan, USA, and environmental parameters were recorded at each collection site. Offspring plants were raised in climate chambers and exposed to one of three temperature treatments: regular occurrence of frost, heat, or constant control conditions. Several traits were assessed: plant growth, time to flowering, and frost and heat resistance. The strongest trait-environment association was between a fast switch to sexual reproduction and weaker growth under frost, and growing in the open, away from trees. The second strongest association was between the trait combination of small plant size and early flowering under control conditions combined with large size under frost, and the combination of environmental conditions of growing close to trees, at low vegetation cover, on dune bottoms. Gene expression analysis by RNA-seq revealed candidate genes involved in multivariate trait differentiation. The results support the hypothesis that in natural populations, many environmental factors impose selection, and that they affect multiple traits, with the relative direction of trait change being complex. The results highlight that heterogeneity in the selection environment over small spatial scales is a main driver of the maintenance of adaptive genetic variation within populations.

Erosion Control and Environment Restoration Plan Development, Matagorda County, Texas. Phase 1: Preliminary Investigation

DTIC Science & Technology

2012-07-01

Matagorda Peninsula east of MCR where a thicker cover of sand with vegetated dunes can be observed. 2.8 Typical beach profile Beach profile shape is a...clay bluffs on the beach face o Small tidal range, defined in Chapter 2, tends to focus wave action on the bluff toe o Breaking waves propel shell...toward the bluff, abrading the bluff toe o Abrasion undercuts the bluff, causing large sections to fail  Slope failure o Cyclical wave loading on

Alien plant invasion in mixed-grass prairie: Effects of vegetation type and anthropogenic disturbance

USGS Publications Warehouse

Larson, D.L.; Anderson, P.J.; Newton, W.

2001-01-01

The ability of alien plant species to invade a region depends not only on attributes of the plant, but on characteristics of the habitat being invaded. Here, we examine characteristics that may influence the success of alien plant invasion in mixed-grass prairie at Theodore Roosevelt National Park, in western North Dakota, USA. The park consists of two geographically separate units with similar vegetation types and management history, which allowed us to examine the effects of native vegetation type, anthropogenic disturbance, and the separate park units on the invasion of native plant communities by alien plant species common to counties surrounding both park units. If matters of chance related to availability of propagules and transient establishment opportunities determine the success of invasion, park unit and anthropogenic disturbance should better explain the variation in alien plant frequency. If invasibility is more strongly related to biotic or physical characteristics of the native plant communities, models of alien plant occurrence should include vegetation type as an explanatory variable. We examined >1300 transects across all vegetation types in both units of the park. Akaike's Information Criterion (AIC) indicated that the fully parameterized model, including the interaction among vegetation type, disturbance, and park unit, best described the distribution of both total number of alien plants per transect and frequency of alien plants on transects where they occurred. Although all vegetation types were invaded by alien plants, mesic communities had both greater numbers and higher frequencies of alien plants than did drier communities. A strong element of stochasticity, reflected in differences in frequencies of individual species between the two park units, suggests that prediction of risk of invasion will always involve uncertainty. In addition, despite well-documented associations between anthropogenic disturbance and alien plant invasion, five of the six most abundant alien species at Theodore Roosevelt National Park had distributions unrelated to disturbance. We recommend that vegetation type be explicitly taken into account when designing monitoring plans for alien species in natural areas.

Grassland vegetation and bird communities in the southern Great Plains of North America

USGS Publications Warehouse

Chapman, R.N.; Engle, David M.; Masters, R.E.; Leslie, David M.

2004-01-01

Structure and composition of vegetation and abundance of breeding birds in grasslands seeded to Old World bluestem (Bothriochloa ischmaeum) were compared to native mixed prairie in the southern Great Plains of North America. Abundance of birds was determined using fixed-radius point counts. Detrended correspondence analysis was used to compare plant community composition and canonical correspondence analysis was used to examine the relationships between plant species composition and vegetation structure with the bird community. Plant species composition differed distinctly between seeded grassland and native mixed prairie, but the differences were not reflected in habitat structure, bird community composition, or abundance of bird species. Seeded grassland was inferior to native mixed prairie in terms of diversity of plant species, but that difference did not translate into meaningful differences in structure that drove habitat selection by breeding birds. Conservation programs that promote establishment of seeded grassland and do not allow for suitable disturbance regimes will selectively benefit a narrow suite of birds regardless of plant species composition. ?? 2004 Elsevier B.V. All rights reserved.

Impacts of feral horses on a desert environment

PubMed Central

2009-01-01

Background Free-ranging horses (Equus caballus) in North America are considered to be feral animals since they are descendents of non-native domestic horses introduced to the continent. We conducted a study in a southern California desert to understand how feral horse movements and horse feces impacted this arid ecosystem. We evaluated five parameters susceptible to horse trampling: soil strength, vegetation cover, percent of nonnative vegetation, plant species diversity, and macroinvertebrate abundance. We also tested whether or not plant cover and species diversity were affected by the presence of horse feces. Results Horse trailing resulted in reduced vegetation cover, compacted soils, and in cases of intermediate intensity disturbance, increased plant species diversity. The presence of horse feces did not affect plant cover, but it did increase native plant diversity. Conclusion Adverse impacts, such as soil compaction and increased erosion potential, were limited to established horse trails. In contrast, increased native plant diversity near trails and feces could be viewed as positive outcomes. Extensive trailing can result in a surprisingly large impact area: we estimate that < 30 horses used > 25 km2 of trails in our study area. PMID:19903355

Impacts of feral horses on a desert environment.

PubMed

Ostermann-Kelm, Stacey D; Atwill, Edward A; Rubin, Esther S; Hendrickson, Larry E; Boyce, Walter M

2009-11-10

Free-ranging horses (Equus caballus) in North America are considered to be feral animals since they are descendents of non-native domestic horses introduced to the continent. We conducted a study in a southern California desert to understand how feral horse movements and horse feces impacted this arid ecosystem. We evaluated five parameters susceptible to horse trampling: soil strength, vegetation cover, percent of nonnative vegetation, plant species diversity, and macroinvertebrate abundance. We also tested whether or not plant cover and species diversity were affected by the presence of horse feces. Horse trailing resulted in reduced vegetation cover, compacted soils, and in cases of intermediate intensity disturbance, increased plant species diversity. The presence of horse feces did not affect plant cover, but it did increase native plant diversity. Adverse impacts, such as soil compaction and increased erosion potential, were limited to established horse trails. In contrast, increased native plant diversity near trails and feces could be viewed as positive outcomes. Extensive trailing can result in a surprisingly large impact area: we estimate that < 30 horses used > 25 km2 of trails in our study area.

A practical scientific approach to riparian vegetation rehabilitation in Australia.

PubMed

Webb, Ashley A; Erskine, Wayne D

2003-08-01

The clearance of indigenous riparian vegetation and removal of large woody debris (LWD) from streams combined with the planting of exotic plant species has resulted in widespread detrimental impacts on the fluvial geomorphology and aquatic ecology of Australian rivers. Vegetation exerts a significant influence on fluvial geomorphology by affecting resistance to flow, bank strength, sediment storage, bed stability and stream morphology and is important for aquatic ecosystem function. As the values of indigenous riparian vegetation are becoming better recognised by Australian river managers, large amounts of money and resources are being invested in the planting of indigenous riparian vegetation as part of river rehabilitation programs. This paper summarises the results of an investigation into the survival, growth and regeneration rates of a series of trial native riparian vegetation plantings on in-channel benches in the Hunter Valley of southeastern Australia. The trials were poorly designed for statistical analysis and the paper highlights a number of shortcomings in the methods used. As a result, a new approach to riparian vegetation rehabilitation is outlined that promotes the use of scientific principles and understanding. Appropriate species should be selected using a combination of remnant vegetation surveys, historical records, palynology and field trials. A number of important factors should be considered in the rehabilitation of riparian vegetation to achieve worthwhile results. These include flood disturbance, vegetation zonation, vegetation succession, substrate composition, corridor planting width, planting techniques, native plant regeneration, LWD recruitment and adaptive ecosystem management. This approach, if adopted, revised and improved by river managers, should result in greater success than has been achieved by previous riparian vegetation rehabilitation efforts in Australia.

Use of saltcedar vegetation by landbirds migrating through the Bosque Del Apache National Wildlife Refuge

Treesearch

Jeffrey F. Kelly; Deborah M. Finch

1999-01-01

We compared diversity, abundance and energetic condition of migrant landbirds captured in four different vegetation types in the Bosque del Apache National Wildlife Refuge. We found lower species diversity among migrants caught in exotic saltcedar vegetation than in native willow or cottonwood. In general, Migrants were most abundant in agricultural edge and least...

Grassland plant composition alters vehicular disturbance effects in Kansas, USA.

PubMed

Dickson, Timothy L; Wilsey, Brian J; Busby, Ryan R; Gebhart, Dick L

2008-05-01

Many "natural" areas are exposed to military or recreational off-road vehicles. The interactive effects of different types of vehicular disturbance on vegetation have rarely been examined, and it has been proposed that some vegetation types are less susceptible to vehicular disturbance than others. At Fort Riley, Kansas, we experimentally tested how different plant community types changed after disturbance from an M1A1 Abrams tank driven at different speeds and turning angles during different seasons. The greatest vegetation change was observed because of driving in the spring in wet soils and the interaction of turning while driving fast (vegetation change was measured with Bray-Curtis dissimilarity). We found that less vegetation change occurred in communities with high amounts of native prairie vegetation than in communities with high amounts of introduced C(3) grasses, which is the first experimental evidence we are aware of that suggests plant communities dominated by introduced C(3) grasses changed more because of vehicular disturbance than communities dominated by native prairie grasses. We also found that vegetation changed linearly with vehicular disturbance intensity, suggesting that at least initially there was no catastrophic shift in vegetation beyond a certain disturbance intensity threshold. Overall, the intensity of vehicular disturbance appeared to play the greatest role in vegetation change, but the plant community type also played a strong role and this should be considered in land use planning. The reasons for greater vegetation change in introduced C(3) grass dominated areas deserve further study.

Groundwater studies in arid areas in Egypt using LANDSAT satellite images

NASA Technical Reports Server (NTRS)

Elshazly, E. M.; Abdelhady, M. A.; Elshazly, M. M.

1977-01-01

Various features are interpreted which have strong bearing on groundwater in the arid environment. These include the nature of geological and lithologic units, structural lineaments, present and old drainage systems, distribution and form of water pools, geomorphologic units, weathering surfaces and other weathering phenomena, desert soils, sand dunes and dune sand accumulations, growths of natural vegetation and agriculture, and salt crusts and other expressions of salinization. There are many impressive examples which illustrate the significance of satellite image interpretation on the regional conditions of groundwater which could be traced and interconnected over several tens or even several hundreds of kilometers. This is especially true in the northern Western Desert of Egypt where ground water issuing from deep strata comes to the surface along ENE-WSW and ESE-WNW fault lines and fracture systems. Another striking example is illustrated by the occurrence of fresh to brackish groundwater on the Mediterranean Sea Coastal Zone of the Western Desert where the groundwater is found in the form of lenses floating on the saline sea water.

Dune mobility and aridity at the desert margin of northern China at a time of peak monsoon strength

USGS Publications Warehouse

Mason, J.A.; Lu, H.; Zhou, Y.; Miao, X.; Swinehart, J.B.; Liu, Z.; Goble, R.J.; Yi, S.

2009-01-01

Wind-blown sands were mobile at many sites along the desert margin in northern China during the early Holocene (11.5-8 ka ago), based on extensive new numerical dating. This mobility implies low effective moisture at the desert margin, in contrast to growing evidence for greater than modern monsoon precipitation at the same time in central and southern China. Dry conditions in the early Holocene at the desert margin can be explained through a dynamic link between enhanced diabatic heating in the core region of the strengthened monsoon and increased subsidence in drylands to the north, combined with high evapotranspiration rates due to high summer temperatures. After 8 ka ago, as the monsoon weakened and lower temperatures reduced evapotranspiration, eolian sands were stabilized by vegetation. Aridity and dune mobility at the desert margin and a strengthened monsoon can both be explained as responses to high summer insolation in the early Holocene. ?? 2009 Geological Society of America.

Discrimination of active and inactive sand from remote sensing - Kelso dunes, Mojave Desert, California

NASA Technical Reports Server (NTRS)

Paisley, Elizabeth C. I.; Lancaster, Nicholas; Gaddis, Lisa R.; Greeley, Ronald

1991-01-01

Landsat TM images, field data, and laboratoray reflectance spectra were examined for the Kelso dunes, Mojave Desert, California to assess the use of visible and near-infrared (VNIR) remote sensing data to discriminate aeolian sand populations on the basis of spectral brightness. Results show that areas of inactive sand have a larger percentage of dark, fine-grained materials compared to those composed of active sand, which contain less dark fines and a higher percentage of quartz sand-size grains. Both areas are spectrally distinct in the VNIR, suggesting that VNIR spectral data can be used to discriminate active and inactive sand populations in the Mojave Desert. Analysis of laboratory spectra was complicated by the presence of magnetite in the active sands, which decreases their laboratory reflectance values to those of inactive sands. For this application, comparison of TM and laboratory spectra suggests that less than 35 percent vegetation cover does not influence the TM spectra.

Restoring coastal wetlands that were ditched for mosquito control: a preliminary assessment of hydro-leveling as a restoration technique

USGS Publications Warehouse

Smith, Thomas J.; Tiling, Ginger; Leasure, Pamela S.

2007-01-01

The wetlands surrounding Tampa Bay, Florida were extensively ditched for mosquito control in the 1950s. Spoil from ditch construction was placed adjacent to the wetlands ditches creating mound-like features (spoil-mounds). These mounds represent a loss of 14% of the wetland area in Tampa Bay. Spoil mounds interfere with tidal flow and are locations for non-native plants to colonize (e.g., Schinus terebinthifolius). Removal of the spoil mounds to eliminate exotic plants, restore native vegetation, and re-establish natural hydrology is a restoration priority for environmental managers. Hydro-leveling, a new technique, was tested in a mangrove forest restoration project in 2004. Hydro-leveling uses a high pressure stream of water to wash sediment from the spoil mound into the adjacent wetland and ditch. To assess the effectiveness of this technique, we conducted vegetation surveys in areas that were hydro-leveled and in non-hydro-leveled areas 3 years post-project. Adult Schinus were reduced but not eliminated from hydro-leveled mounds. Schinus seedlings however were absent from hydro-leveled sites. Colonization by native species was sparse. Mangrove seedlings were essentially absent (≈2 m−2) from the centers of hydro-leveled mounds and were in low density on their edges (17 m−2) in comparison to surrounding mangrove forests (105 m−2). Hydro-leveling resulted in mortality of mangroves adjacent to the mounds being leveled. This was probably caused by burial of pneumatophores during the hydro-leveling process. For hydro-leveling to be a useful and successful restoration technique several requirements must be met. Spoil mounds must be lowered to the level of the surrounding wetlands. Spoil must be distributed further into the adjacent wetland to prevent burial of nearby native vegetation. Finally, native species may need to be planted on hydro-leveled areas to speed up the re-vegetation process.

Early recovery of a Hawaiian lowland rainforest following clearcutting at Kalapana on the Island of Hawaii

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

Grossman, D.H.

The recovery of lowland rainforest vegetation on the Island of Hawaii was evaluated 2 years after clearcutting. Rainforest quality was assessed with regeneration success associated with the environmental changes. Sixty-three percent of the 57 vascular species in the forest were native to the Hawaiian rainforest. Phanerophytes were the most important life form. The presence of Psidium cattleianum and other alien species demonstrated disturbances had occurred in selected areas prior to the clearcutting. Two years after clearcutting (1987), only 24% of the 101 species coming into the clearcut area were native. The shrubs, micro- and nano-phanerophyte, were the dominant life forms,more » represented by Pipturus albidus, a native rainforest shrub or tree, and four non-native shrub species. Metrosideros polymorpha, the dominant tree in the native forest, was successfully regenerating from seed across the clear-cut area. The forest seedbank analysis also demonstrated that Metrosideros, along with the seeds of important exotic species colonizing the clearcut area were presented in the forest soils. The forest and clearcut species had a high rate of correlation with the elevation gradient. The underlying lava flows strong influenced past and present vegetation associations. In the clearcut area, the degree of compaction and distance from the forest were critical factors determining the composition of recovering vegetation. The microclimate variables of soils, significantly altered due to the effects of clearcutting, and competition from weeds probably lead to poor germination and growth of native rainforest species. This native forest is not pristine, but unique in stature, in complex of cohort stands, and in position on the landscape. It is extremely prone to species composition shift following perturbation, due to the presence of the weed seedbank in the forest seedbank as demonstrated in the dominance of these species across the clearcut area.« less

Effects of Introduced and Indigenous Viruses on Native Plants: Exploring Their Disease Causing Potential at the Agro-Ecological Interface

PubMed Central

Vincent, Stuart J.; Coutts, Brenda A.; Jones, Roger A. C.

2014-01-01

The ever increasing movement of viruses around the world poses a major threat to plants growing in cultivated and natural ecosystems. Both generalist and specialist viruses move via trade in plants and plant products. Their potential to damage cultivated plants is well understood, but little attention has been given to the threat such viruses pose to plant biodiversity. To address this, we studied their impact, and that of indigenous viruses, on native plants from a global biodiversity hot spot in an isolated region where agriculture is very recent (<185 years), making it possible to distinguish between introduced and indigenous viruses readily. To establish their potential to cause severe or mild systemic symptoms in different native plant species, we used introduced generalist and specialist viruses, and indigenous viruses, to inoculate plants of 15 native species belonging to eight families. We also measured resulting losses in biomass and reproductive ability for some host–virus combinations. In addition, we sampled native plants growing over a wide area to increase knowledge of natural infection with introduced viruses. The results suggest that generalist introduced viruses and indigenous viruses from other hosts pose a greater potential threat than introduced specialist viruses to populations of native plants encountered for the first time. Some introduced generalist viruses infected plants in more families than others and so pose a greater potential threat to biodiversity. The indigenous viruses tested were often surprisingly virulent when they infected native plant species they were not adapted to. These results are relevant to managing virus disease in new encounter scenarios at the agro-ecological interface between managed and natural vegetation, and within other disturbed natural vegetation situations. They are also relevant for establishing conservation policies for endangered plant species and avoiding spread of damaging viruses to undisturbed natural vegetation beyond the agro-ecological interface. PMID:24621926

Pest management through tropical tree conservation

USDA-ARS?s Scientific Manuscript database

When discussing the need to improve conservation programs for native forests, arguments such as the role of vegetation in water catchment and soil conservation or as sources of food, medicines, firewood and lumber, and habitat for wildlife are commonly used. Here we argue that many native species o...

Differences in Leaf Flammability, Leaf Traits and Flammability-Trait Relationships between Native and Exotic Plant Species of Dry Sclerophyll Forest

PubMed Central

Murray, Brad R.; Hardstaff, Lyndle K.; Phillips, Megan L.

2013-01-01

The flammability of plant leaves influences the spread of fire through vegetation. Exotic plants invading native vegetation may increase the spread of bushfires if their leaves are more flammable than native leaves. We compared fresh-leaf and dry-leaf flammability (time to ignition) between 52 native and 27 exotic plant species inhabiting dry sclerophyll forest. We found that mean time to ignition was significantly faster in dry exotic leaves than in dry native leaves. There was no significant native-exotic difference in mean time to ignition for fresh leaves. The significantly higher fresh-leaf water content that was found in exotics, lost in the conversion from a fresh to dry state, suggests that leaf water provides an important buffering effect that leads to equivalent mean time to ignition in fresh exotic and native leaves. Exotic leaves were also significantly wider, longer and broader in area with significantly higher specific leaf area–but not thicker–than native leaves. We examined scaling relationships between leaf flammability and leaf size (leaf width, length, area, specific leaf area and thickness). While exotics occupied the comparatively larger and more flammable end of the leaf size-flammability spectrum in general, leaf flammability was significantly correlated with all measures of leaf size except leaf thickness in both native and exotic species such that larger leaves were faster to ignite. Our findings for increased flammability linked with larger leaf size in exotics demonstrate that exotic plant species have the potential to increase the spread of bushfires in dry sclerophyll forest. PMID:24260169

Review of Phosphate in soils: Interaction with micronutrients, radionuclides, and heavy metals

USDA-ARS?s Scientific Manuscript database

Phosphate-phosphorus present in the vadose zone of soil as native, added, or residual fertilizer influences the retention, transport, and bioavailability of heavy metals, metalloids, or metallic radionuclides to aboveground vegetation, soil microorganisms, and fauna that browse that vegetation, or d...

Prescriptions for Tough Vegetation Problems

Treesearch

James H. Miller

1999-01-01

Most tough forst vegetation problems are caused by non-native plants. These foreign invaders-often called exotic, alien, or noxious weeds-occur as trees, shrubs, vines, and grasses. Some have been introduced into this country accidentally, but most were brought here intentionally for livestock forage or as ornamentals.

Grassland birds wintering at U.S. Navy facilities in southern Texas

USGS Publications Warehouse

Woodin, Marc C.; Skoruppa, Mary Kay; Bryan, Pearce D.; Ruddy, Amanda J.; Hickman, Graham C.

2010-01-01

Grassland birds have undergone widespread decline throughout North America during the past several decades. Causes of this decline include habitat loss and fragmentation because of conversion of grasslands to cropland, afforestation in the East, brush and shrub invasion in the Southwest and western United States, and planting of exotic grass species to enhance forage production. A large number of exotic plant species, including grasses, have been introduced in North America, but most research on the effects of these invasions on birds has been limited to breeding birds, primarily those in northern latitudes. Research on the effects of exotic grasses on birds in winter has been extremely limited.This is the first study in southern Texas to examine and compare winter bird responses to native and exotic grasslands. This study was conducted during a period of six years (2003–2009) on United States Navy facilities in southern Texas including Naval Air Station–Corpus Christi, Naval Air Station–Kingsville, Naval Auxiliary Landing Field Waldron, Naval Auxiliary Landing Field Orange Grove, and Escondido Ranch, all of which contained examples of native grasslands, exotic grasslands, or both. Data from native and exotic grasslands were collected and compared for bird abundance and diversity; ground cover, vegetation density, and floristic diversity; bird and vegetation relationships; diversity of insects and arachnids; and seed abundance and diversity. Effects of management treatments in exotic grasslands were evaluated by comparing numbers and diversity of birds and small mammals in mowed, burned, and control areas.To determine bird abundance and bird species richness, birds were surveyed monthly (December–February) during the winters of 2003–2008 in transects (100 meter × 20 meter) located in native and exotic grasslands distributed at all five U.S. Navy facilities. To compare vegetation in native and exotic grasslands, vegetation characteristics were measured during 2003–2008 in the same transects used for bird surveys and included five measures of ground cover, plus estimates of plant species richness, vegetation density (visual obstruction) at two different heights, and shrub numbers. These data, plus seasonal rainfall, were then used to evaluate components of variation in native and exotic grasslands. Relations between total bird numbers and bird species richness with environmental variation in native and exotic grasslands were compared. To compare diversity of arthropods in native and exotic grasslands, insects and arachnids were collected using three different methodologies (standardized sweep-net, random sweep-net, and pitfall traps) during four seasons, (2005–2006), at Naval Air Station–Corpus Christi, Naval Auxiliary Landing Field Waldron, and Naval Air Station–Kingsville. To compare seed abundance and diversity between native and exotic grasslands, seeds were collected for two winters (2004–2006) at Naval Air Station–Corpus Christi and Naval Air Station–Kingsville. To evaluate effects of management on grassland vertebrates, abundance and diversity of birds and small mammals were estimated and compared in exotic grasses subjected to mowing, burning, or no active management (control) for one full year (2008–2009).Observations were made of 1,044 birds of 30 species in grassland transects during five winters. The Savannah Sparrow (Passerculus sandwichensis) was the most common bird, which, with 644 detections, accounted for 63 percent of all individuals identified to species. Meadowlarks (Sturnella spp.) and Le Conte’s Sparrows (Ammodramus leconteii) were the second (10 percent) and third (7 percent) most abundant bird species, respectively. Six of the seven most abundant species detected in grasslands were grassland species, and their numbers accounted for 87 percent of all birds, but 20 of the 30 species (67 percent) that used grasslands were not grassland species. Seven species observed in grassland transects during the study were Species of Conservation Concern: Le Conte’s Sparrow, Sedge Wren (Cistothorus platensis), Grasshopper Sparrow (Ammodramus savannarum), Long-billed Curlew (Numenius americanus), Sprague’s Pipit (Anthus spragueii), Cassin’s Sparrow (Aimophila cassinii), and Loggerhead Shrike (Lanius ludovicianus). Native grasslands consistently supported greater bird species richness than exotic grasslands. In one winter, exotic grasslands supported more birds than native grasslands.Native grasslands were determined to have more forb cover, more bare ground, and greater plant species richness than exotic grasslands, whereas exotic grasslands were characterized by more grass cover and relatively greater vegetation density during dry years. Not only did these individual measures differ between native and exotic grasslands, but components of variation also differed. In native grasslands, grass density and cover contributed more to variation, whereas in exotic grasslands, non-grass vegetation was a greater component of variation. Total bird numbers and bird species richness in native grasslands were related to the principal component that contained a measure of litter cover. Total bird numbers and bird species richness in exotic grasslands indicated no significant relationships with any of the principal components of variation.The two most common insect orders in native grasslands were Hymenoptera and Coleoptera, which accounted for 42 percent of all insects. The two most common insect orders in exotic grasslands were Hemiptera and Homoptera, which accounted for about 80 percent of all insects. Insect family richness was greater in exotic grasslands than in native grasslands in two of four seasons. Proportions of arachnid families were similar in native and exotic grasslands, but arachnid family richness was greater in exotic grasslands than in native grasslands.Abundance of seeds was greater in exotic than in native grasslands. However, seed diversity was greater in native grasslands than in exotic grasslands.Among the three types of management (mowed, burned, and control) applied to exotic grasses, birds were most abundant in the mowed area. Sedge Wrens, however, were never encountered in mowed sites. Meadowlarks were similarly abundant in all treatments, but Le Conte’s Sparrows were detected only in the control (unmanaged) area. Hispid cotton rats (Sigmodon hispidus) accounted for 93 percent of all rodent captures, with the number of captures peaking December through February. Hispid cotton rat numbers and total rodent numbers were greatest in control and pre-burn areas, and lowest in the mowed area. Mammal diversity, however, was greatest in the mowed habitat.Native and exotic grasslands differed essentially in all categories (bird numbers and diversity, vegetation characteristics, components of variation, diversity of insects and arachnids, and seed abundance and diversity) used to measure and compare them. This indicates that fundamental ecosystem processes have been altered after native grasslands have undergone invasion and ultimate domination by exotic grass species. Future research in Texas grassland ecosystems is essential because: 1) Texas sustains more area in grasslands than any other state or province in the Central Flyway; 2) Texas serves as the winter destination or migration pathway for hundreds of species of birds, including winter residents and Neotropical migrants; 3) ecology, distribution, and numbers of grassland birds wintering in southern latitudes of the United States remains poorly understood; and 4) climate change threatens to further accelerate advances of invading grass species.

Post-wildfire recovery of riparian vegetation during a period of water scarcity in the southwestern USA

Treesearch

D. Max Smith; Deborah M. Finch; Christian Gunning; Roy Jemison; Jeffrey F. Kelly

2009-01-01

Wildland fires occur with increasing frequency in southwestern riparian forests, yet little is known about the effects of fire on populations of native and exotic vegetation. From 2003 to 2006, we monitored recovering woody vegetation in wildfire sites in the bosque (riparian forest) along the Middle Rio Grande of central New Mexico, USA. To examine recovery potential...

Discrimination of coastal wetland environments in the Amazon region based on multi-polarized L-band airborne Synthetic Aperture Radar imagery

NASA Astrophysics Data System (ADS)

Souza-Filho, Pedro Walfir M.; Paradella, Waldir R.; Rodrigues, Suzan W. P.; Costa, Francisco R.; Mura, José C.; Gonçalves, Fabrício D.

2011-11-01

This study assessed the use of multi-polarized L-band images for the identification of coastal wetland environments in the Amazon coast region of northern Brazil. Data were acquired with a SAR R99B sensor from the Amazon Surveillance System (SIVAM) on board a Brazilian Air Force jet. Flights took place in the framework of the 2005 MAPSAR simulation campaign, a German-Brazilian feasibility study focusing on a L-band SAR satellite. Information retrieval was based on the recognition of the interaction between a radar signal and shallow-water morphology in intertidal areas, coastal dunes, mangroves, marshes and the coastal plateau. Regarding the performance of polarizations, VV was superior for recognizing intertidal area morphology under low spring tide conditions; HH for mapping coastal environments covered with forest and scrub vegetation such as mangrove and vegetated dunes, and HV was suitable for distinguishing transition zones between mangroves and coastal plateau. The statistical results for the classification maps expressed by kappa index and general accuracy were 83.3% and 0.734 for the multi-polarized color composition (R-HH, G-HV, B-VV), 80.7% and 0.694% for HH, 79.7% and 0.673% for VV, and 77.9% and 0.645% for HV amplitude image. The results indicate that use of multi-polarized L-band SAR is a valuable source of information aiming at the identification and discrimination of distinct geomorphic targets in tropical wetlands.

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

Treesearch

Dumitru Salajanu; Dennis M. Jacobs

2009-01-01

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

Fidelity of the Asian beetle Lilioceris egena (Weise) to air potato (Dioscorea bulbifera L.)

USDA-ARS?s Scientific Manuscript database

TECHNICAL ABSTRACT The invasive Asian vine Dioscorea bulbifera (air potato) trellises up native trees in a variety of habitats in Florida and displaces native understory vegetation with its associated fauna, thereby altering community composition. A biological control program directed at this vine ...

Towards restoration of Hawaiian tropical dry forests: the Kaupulehu outplanting programme

Treesearch

Susan Cordell; Moana McClellan; Yvonne Yarber Carter; Lisa J. Hadway

2008-01-01

Hawaiian tropical dry forests contain diverse assemblages of woody canopy species, including many endemic and endangered species that warrant conservation attention before completely disappearing. Today, tropical dry forests in Hawaii are not viable ecosystems. Poor land use practices, fragmentation, non-native plant invasions, and inadequate native vegetation...

Tidal and seasonal effects on survival rates of the endangered California clapper rail: Does invasive Spartina facilitate greater survival in a dynamic environment?

USGS Publications Warehouse

Overton, Cory T.; Casazza, Michael L.; Takekawa, John Y.; Strong, Donald R.; Holyoak, Marcel

2014-01-01

Invasive species frequently degrade habitats, disturb ecosystem processes, and can increase the likelihood of extinction of imperiled populations. However, novel or enhanced functions provided by invading species may reduce the impact of processes that limit populations. It is important to recognize how invasive species benefit endangered species to determine overall effects on sensitive ecosystems. For example, since the 1990s, hybrid Spartina (Spartina foliosa × alterniflora) has expanded throughout South San Francisco Bay, USA, supplanting native vegetation and invading mudflats. The endangered California clapper rail (Rallus longirostris obsoletus) uses the tall, dense hybrid Spartina for cover and nesting, but the effects of hybrid Spartina on clapper rail survival was unknown. We estimated survival rates of 108 radio-marked California clapper rails in South San Francisco Bay from January 2007 to March 2010, a period of extensive hybrid Spartina eradication, with Kaplan–Meier product limit estimators. Clapper rail survival patterns were consistent with hybrid Spartina providing increased refuge cover from predators during tidal extremes which flood native vegetation, particularly during the winter when the vegetation senesces. Model averaged annual survival rates within hybrid Spartina dominated marshes before eradication (Ŝ = 0.466) were greater than the same marshes posttreatment (Ŝ = 0.275) and a marsh dominated by native vegetation (Ŝ = 0.272). However, models with and without marsh treatment as explanatory factor for survival rates had nearly equivalent support in the observed data, lending ambiguity as to whether hybrid Spartina facilitated greater survival rates than native marshland. Conservation actions to aid in recovery of this endangered species should recognize the importance of available of high tide refugia, particularly in light of invasive species eradication programs and projections of future sea-level rise.

Dynamics of Bottomland Geomorphology and Vegetation Along a Dammed, Arid Region River: Implications for Streamflow Management

NASA Astrophysics Data System (ADS)

Shafroth, P. B.; House, P. K.

2007-05-01

In arid and semiarid western North America, floodplain forests dominated by native cottonwood and willow trees are highly valued as wildlife habitat and preferred recreation sites and are thus the focus of conservation efforts. The Bill Williams River harbors some of the most extensive native floodplain forests in the lower Colorado River region. Our work is aimed at understanding the dynamics of the Bill Williams River floodplain forests, in the context of pre- and post-dam hydrology and geomorphology. We have mapped bottomland geomorphology and vegetation using seven sets of orthorectified aerial photographs spanning more than 50 years. Two sets of photos (1953 and 1964) pre-date the completion of Alamo Dam, a large flood control structure; and three sets of photos (1996, 2002, and 2005) are from an era during which streamflow downstream of the dam has been managed to promote the establishment and survival of native floodplain forest. Comparison of the aerial photographs to LiDAR data collected in 2005 is providing a framework for quantifying changes in valley bottom morphology and estimating reach-scale changes in volumes of stored and evacuated sediment between 1953 and 2005. Furthermore, comparison of the extent of pre-dam active channel in 1953 with the extent of floodwaters from a regulated moderate flood in 2005 provides an approximation of the predominant patterns of aggradation and degradation in the system over this interval of time. Flood magnitude on the Bill Williams has been dramatically reduced since the closure of Alamo Dam in 1968, and low flows have increased considerably since 1979. Channels along the Bill Williams R. narrowed an average of 111 m (71 %) between 1953 and 1987, with most narrowing occurring after dam closure. Multiple regression analysis revealed significant relationships among flood power, summer flows, intermittency (independent variables) and channel width (dependent variable). Concurrent with channel narrowing was an expansion of dense floodplain vegetation, consisting primarily of native cottonwood and willow and non-native tamarisk shrubs. Moderate flood releases (~7000 ft3/s) from Alamo Dam in the early 1990's widened the river channel and resulted in the establishment of new woody vegetation. For the following nine years, relatively steady, low discharges were released from the dam, resulting in channel narrowing, extensive beaver pond creation, and dense vegetation growth. Moderate flood releases in 2005 again widened channels, destroyed beaver ponds, and created conditions suitable for new vegetation establishment. In addition to understanding the specific conditions along the Bill Williams River, our work should contribute to a more general understanding of connections between fluvial processes and floodplain vegetation, in the contexts of geomorphic response downstream of a large dam and efforts to manage streamflow for ecological benefits downstream.

Riparian vegetation as an indicator of riparian condition: Detecting departures from historic condition across the North American West.

PubMed

Macfarlane, William W; Gilbert, Jordan T; Jensen, Martha L; Gilbert, Joshua D; Hough-Snee, Nate; McHugh, Peter A; Wheaton, Joseph M; Bennett, Stephen N

2017-11-01

Floodplain riparian ecosystems support unique vegetation communities and high biodiversity relative to terrestrial landscapes. Accordingly, estimating riparian ecosystem health across landscapes is critical for sustainable river management. However, methods that identify local riparian vegetation condition, an effective proxy for riparian health, have not been applied across broad, regional extents. Here we present an index to assess reach-scale (500 m segment) riparian vegetation condition across entire drainage networks within large, physiographically-diverse regions. We estimated riparian vegetation condition for 53,250 km of perennial streams and rivers, 25,685 km in Utah, and 27,565 km in twelve watersheds of the interior Columbia River Basin (CRB), USA. We used nationally available, existing land cover classification derived from 30 m Landsat imagery (LANDFIRE EVT) and a modeled estimate of pre-European settlement land cover (LANDFIRE BpS). The index characterizes riparian vegetation condition as the ratio of existing native riparian vegetation cover to pre-European settlement riparian vegetation cover at a given reach. Roughly 62% of Utah and 48% of CRB watersheds showed significant (>33%) to large (>66%) departure from historic condition. Riparian vegetation change was predominantly caused by human land-use impacts (development and agriculture), or vegetation change (native riparian to invasive or upland vegetation types) that likely resulted from flow and disturbance regime alteration. Through comparisons to ground-based classification results, we estimate the existing vegetation component of the index to be 85% accurate. Our assessments yielded riparian condition maps that will help resource managers better prioritize sites and treatments for reach-scale conservation and restoration activities. Copyright © 2016 Elsevier Ltd. All rights reserved.

DEVELOPMENT OF AN INDEX OF ALIEN SPECIES INVASIVENESS: AN AID TO ASSESSING RIPARIAN VEGETATION CONDITION

EPA Science Inventory

Many riparian areas are invaded by alien plant species that negatively affect native species composition, community dynamics and ecosystem properties. We sampled vegetation along reaches of 31 low order streams in eastern Oregon, and characterized species assemblages at patch an...

Evaluating Vegetation Potential for Wildfire Impacted Watershed Using a Bayesian Network Modeling Approach

NASA Astrophysics Data System (ADS)

Jaramillo, L. V.; Stone, M. C.; Morrison, R. R.

2017-12-01

Decision-making for natural resource management is complex especially for fire impacted watersheds in the Southwestern US because of the vital importance of water resources, exorbitant cost of fire management and restoration, and the risks of the wildland-urban interface (WUI). While riparian and terrestrial vegetation are extremely important to ecosystem health and provide ecosystem services, loss of vegetation due to wildfire, post-fire flooding, and debris flows can lead to further degradation of the watershed and increased vulnerability to erosion and debris flow. Land managers are charged with taking measures to mitigate degradation of the watershed effectively and efficiently with limited time, money, and data. For our study, a Bayesian network (BN) approach is implemented to understand vegetation potential for Kashe-Katuwe Tent Rocks National Monument in the fire-impacted Peralta Canyon Watershed, New Mexico, USA. We implement both two-dimensional hydrodynamic and Bayesian network modeling to incorporate spatial variability in the system. Our coupled modeling framework presents vegetation recruitment and succession potential for three representative plant types (native riparian, native terrestrial, and non-native) under several hydrologic scenarios and management actions. In our BN model, we use variables that address timing, hydrologic, and groundwater conditions as well as recruitment and succession constraints for the plant types based on expert knowledge and literature. Our approach allows us to utilize small and incomplete data, incorporate expert knowledge, and explicitly account for uncertainty in the system. Our findings can be used to help land managers and local decision-makers determine their plan of action to increase watershed health and resilience.

2009 weather and aeolian sand-transport data from the Colorado River corridor, Grand Canyon, Arizona

USGS Publications Warehouse

Draut, Amy E.; Sondossi, Hoda A.; Dealy, Timothy P.; Hazel, Joseph E.; Fairley, Helen C.; Brown, Christopher R.

2010-01-01

This report presents measurements of weather parameters and aeolian sand transport made in 2009 near selected archeological sites in the Colorado River corridor through Grand Canyon, Ariz. The quantitative methods and data discussed here form a basis for monitoring ecosystem processes that affect archeological-site stability. Combined with forthcoming work to evaluate landscape evolution at nearby archeological sites, these data can be used to document the relation between physical processes, including weather and aeolian sand transport, and their effects on the physical integrity of archeological sites. Data collected in 2009 reveal event- and seasonal-scale variations in rainfall, wind, temperature, humidity, and barometric pressure. Broad seasonal changes in aeolian sediment flux are also apparent at most study sites. Differences in weather patterns between 2008 and 2009 included an earlier spring windy season, greater spring precipitation even though 2009 annual rainfall totals were in general substantially lower than in 2008, and earlier onset of the reduced diurnal barometric-pressure fluctuations commonly associated with summer monsoon conditions. Weather patterns in middle to late 2009 were apparently affected by a transition of the ENSO cycle from a neutral phase to the El Ni?o phase. The continuation of monitoring that began in 2007, and installation of additional equipment at several new sites in early 2008, allowed evaluation of the effects of the March 2008 high-flow experiment (HFE) on aeolian sand transport. As reported earlier, at 2 of the 9 sites studied, spring and summer winds in 2008 reworked the HFE sandbars to form new aeolian dunes, where sand moved inland toward larger, well-established dune fields. Observations in 2009 showed that farther inland migration of the dune at one of those two sites is likely inhibited by vegetation. At the other location, the new aeolian dune form was found to have moved 10 m inland toward older, well-established dunes during 2009, resulting in landward transport of several hundred cubic meters of new sand upslope and above the elevation reached by the peak HFE water level.

Modeling aeolian dune and dune field evolution

NASA Astrophysics Data System (ADS)

Diniega, Serina

Aeolian sand dune morphologies and sizes are strongly connected to the environmental context and physical processes active since dune formation. As such, the patterns and measurable features found within dunes and dune fields can be interpreted as records of environmental conditions. Using mathematical models of dune and dune field evolution, it should be possible to quantitatively predict dune field dynamics from current conditions or to determine past field conditions based on present-day observations. In this dissertation, we focus on the construction and quantitative analysis of a continuum dune evolution model. We then apply this model towards interpretation of the formative history of terrestrial and martian dunes and dune fields. Our first aim is to identify the controls for the characteristic lengthscales seen in patterned dune fields. Variations in sand flux, binary dune interactions, and topography are evaluated with respect to evolution of individual dunes. Through the use of both quantitative and qualitative multiscale models, these results are then extended to determine the role such processes may play in (de)stabilization of the dune field. We find that sand flux variations and topography generally destabilize dune fields, while dune collisions can yield more similarly-sized dunes. We construct and apply a phenomenological macroscale dune evolution model to then quantitatively demonstrate how dune collisions cause a dune field to evolve into a set of uniformly-sized dunes. Our second goal is to investigate the influence of reversing winds and polar processes in relation to dune slope and morphology. Using numerical experiments, we investigate possible causes of distinctive morphologies seen in Antarctic and martian polar dunes. Finally, we discuss possible model extensions and needed observations that will enable the inclusion of more realistic physical environments in the dune and dune field evolution models. By elucidating the qualitative and quantitative connections between environmental conditions, physical processes, and resultant dune and dune field morphologies, this research furthers our ability to interpret spacecraft images of dune fields, and to use present-day observations to improve our understanding of past terrestrial and martian environments.

Testing model parameters for wave-induced dune erosion using observations from Hurricane Sandy

NASA Astrophysics Data System (ADS)

Overbeck, J. R.; Long, J. W.; Stockdon, H. F.

2017-01-01

Models of dune erosion depend on a set of assumptions that dictate the predicted evolution of dunes throughout the duration of a storm. Lidar observations made before and after Hurricane Sandy at over 800 profiles with diverse dune elevations, widths, and volumes are used to quantify specific dune erosion model parameters including the dune face slope, which controls dune avalanching, and the trajectory of the dune toe, which controls dune migration. Wave-impact models of dune erosion assume a vertical dune face and erosion of the dune toe along the foreshore beach slope. Observations presented here show that these assumptions are not always valid and require additional testing if these models are to be used to predict coastal vulnerability for decision-making purposes. Observed dune face slopes steepened by 43% yet did not become vertical faces, and only 50% of the dunes evolved along a trajectory similar to the foreshore beach slope. Observations also indicate that dune crests were lowered during dune erosion. Moreover, analysis showed a correspondence between dune lowering and narrower beaches, smaller dune volumes, and/or longer wave impact.

Testing model parameters for wave‐induced dune erosion using observations from Hurricane Sandy

USGS Publications Warehouse

Overbeck, Jacquelyn R.; Long, Joseph W.; Stockdon, Hilary F.

2017-01-01

Models of dune erosion depend on a set of assumptions that dictate the predicted evolution of dunes throughout the duration of a storm. Lidar observations made before and after Hurricane Sandy at over 800 profiles with diverse dune elevations, widths, and volumes are used to quantify specific dune erosion model parameters including the dune face slope, which controls dune avalanching, and the trajectory of the dune toe, which controls dune migration. Wave‐impact models of dune erosion assume a vertical dune face and erosion of the dune toe along the foreshore beach slope. Observations presented here show that these assumptions are not always valid and require additional testing if these models are to be used to predict coastal vulnerability for decision‐making purposes. Observed dune face slopes steepened by 43% yet did not become vertical faces, and only 50% of the dunes evolved along a trajectory similar to the foreshore beach slope. Observations also indicate that dune crests were lowered during dune erosion. Moreover, analysis showed a correspondence between dune lowering and narrower beaches, smaller dune volumes, and/or longer wave impact.

Terrestrial forest management plan for Palmyra Atoll

USGS Publications Warehouse

Hathaway, Stacie A.; McEachern, Kathryn; Fisher, Robert N.

2011-01-01

This 'Terrestrial Forest Management Plan for Palmyra Atoll' was developed by the U.S. Geological Survey (USGS) for The Nature Conservancy (TNC) Palmyra Program to refine and expand goals and objectives developed through the Conservation Action Plan process. It is one in a series of adaptive management plans designed to achieve TNC's mission toward the protection and enhancement of native wildlife and habitat. The 'Terrestrial Forest Management Plan for Palmyra Atoll' focuses on ecosystem integrity and specifically identifies and addresses issues related to assessing the status and distribution of resources, as well as the pressures acting upon them, most specifically nonnative and potentially invasive species. The plan, which presents strategies for increasing ecosystem integrity, provides a framework to implement and track the progress of conservation and restoration goals related to terrestrial resources on Palmyra Atoll. The report in its present form is intended to be an overview of what is known about historical and current forest resources; it is not an exhaustive review of all available literature relevant to forest management but an attempt to assemble as much information specific to Palmyra Atoll as possible. Palmyra Atoll is one of the Northern Line Islands in the Pacific Ocean southwest of the Hawai`ian Islands. It consists of many heavily vegetated islets arranged in a horseshoe pattern around four lagoons and surrounded by a coral reef. The terrestrial ecosystem consists of three primary native vegetation types: Pisonia grandis forest, coastal strand forest, and grassland. Among these vegetation types, the health and extent of Pisonia grandis forest is of particular concern. Overall, the three vegetation types support 25 native plant species (two of which may be extirpated), 14 species of sea birds, six shore birds, at least one native reptile, at least seven native insects, and six native land crabs. Green and hawksbill turtles forage at Palmyra Atoll, and though rarely documented, beach nesting could be affected by terrestrial management actions. There are various nonnative or invasive species throughout the terrestrial ecosystem. The most notable examples of terrestrial invasive species include coconut palms (Cocos nucifera) and black rats (Rattus rattus). Although it is unclear whether they are nonnative, coconut palms are currently the most dominant plant across Palmyra Atoll. They compete with native plant species for space and resources and are potentially detrimental to sea birds dependent on native vegetation for roosting and nesting habitat. This competition in turn impacts nutrient resource availability, thereby reshaping energy flow in the ecosystem. Black rats are known to prey on ground-nesting sea birds and are likely responsible for the lack of burrowing sea bird reproduction at Palmyra Atoll. In addition, they may be facilitating the invasion of other nonnative species and negatively impacting other native fauna. Although the extent and impacts of these and other nonnative and (or) invasive species are not fully understood, the extent and impacts are clearly a threat to the native species and one of the most urgent threats to the overall ecosystem integrity of Palmyra Atoll. This 'Terrestrial Forest Management Plan for Palmyra Atoll' addresses issues related to invasive species and other problems. Priority goals are established as are associated objectives and strategies. The overarching goal is to perpetuate and where possible restore terrestrial ecosystem integrity through the following techniques: 1. Habitat management: Maintain and enhance habitat to the extent possible to sustain thriving Pisonia grandis forest, coastal strand forest, endemic grassland, self-sustaining populations of sea birds, shore birds, coconut crabs, native lizards, and native insects. 2. Monitoring and assessment: Acquire information on distribution and abundance as needed for conservation of each resour

Historical analysis of riparian vegetation change in response to shifting management objectives on the Middle Rio Grande

USGS Publications Warehouse

Petrakis, Roy; van Leeuwen, Willem J.D.; Villarreal, Miguel; Tashjian, Paul; Dello Russo, Regina; Scott, Christopher A.

2017-01-01

Riparian ecosystems are valuable to the ecological and human communities that depend on them. Over the past century, they have been subject to shifting management practices to maximize human use and ecosystem services, creating a complex relationship between water policy, management, and the natural ecosystem. This has necessitated research on the spatial and temporal dynamics of riparian vegetation change. The San Acacia Reach of the Middle Rio Grande has experienced multiple management and river flow fluctuations, resulting in threats to its riparian and aquatic ecosystems. This research uses remote sensing data, GIS, a review of management decisions, and an assessment of climate to both quantify how riparian vegetation has been altered over time and provide interpretations of the relationships between riparian change and shifting climate and management objectives. This research focused on four management phases from 1935 to 2014, each highlighting different management practices and climate-driven river patterns, providing unique opportunities to observe a direct relationship between river management, climate, and riparian response. Overall, we believe that management practices coupled with reduced surface river-flows with limited overbank flooding influenced the compositional and spatial patterns of vegetation, including possibly increasing non-native vegetation coverage. However, recent restoration efforts have begun to reduce non-native vegetation coverage.

Relationships between soil parameters and vegetation in abandoned terrace fields vs. non-terraced fields in arid lands (Lanzarote, Spain): An opportunity for restoration

NASA Astrophysics Data System (ADS)

Arévalo, José Ramón; Fernández-Lugo, Silvia; Reyes-Betancort, J. Alfredo; Tejedor, Marisa; Jiménez, Concepción; Díaz, Francisco J.

2017-11-01

Over 90% of terraced fields have been abandoned on the island of Lanzarote in the last 40 years. The present work analyses the effects of abandonment on the soil and vegetation recovery of terraced field agroecosystems by comparing them with adjacent non-terraced fields in Lanzarote, Canary Islands (Spain). This information is necessary to take the appropriate management actions to achieve goals such as soil protection and biodiversity conservation. Results indicate that terraced fields display better soil quality than non-terraced ones, as shown by the significant differences found in parameters such as SAR, exchangeable Na, CaCO3, B content, moisture content or soil depth. Moreover, the terraced fields' plant community has more species similarities with the native plant community when compared with non-terraced areas. Owing to characteristics such as deeper soils, more water capacity, lower salinity and less sodic soils, terraced soils provide better conditions for passive restoration of both soil and vegetation. Therefore, the recovery and maintenance of wall structures and revegetation with native/endemic species are proposed to promote the restoration of native systems and preserve a landscape with cultural and aesthetic value.

Repeatability and implementation of a forest vegetation indicator.

Treesearch

Andrew N. Gray; David L. Azuma

2005-01-01

The composition, diversity, and structure of vascular plants are important indicators of forest health. Changes in species diversity, structural diversity, and the abundance of non-native species are common national concerns, and are part of the international criteria for assessing sustainability of forestry practices. The vegetation indicator for the national Forest...

Quantifying livestock effects on bunchgrass vegetation with Landsat ETM+ data across a single growing season

USDA-ARS?s Scientific Manuscript database

Working grassland systems provide important habitat for native biodiversity and forage for livestock, with proper livestock grazing playing an important role for sustainable ecosystem function. Traditional in-field techniques to monitor the effects of grazing on vegetation are costly and limited to ...

ALIEN SPECIES IMPORTANTANCE IN NATIVE VEGETATION ALONG WADEABLE STREAMS, JOHN DAY RIVER BASIN, OREGON, USA

EPA Science Inventory

We evaluated the importance of alien species in existing vegetation along wadeable streams of a large, topographically diverse river basin in eastern Oregon, USA; sampling 165 plots (30 × 30 m) across 29 randomly selected 1-km stream reaches. Plots represented eight streamside co...

Evaluation of barrier treatments on native vegetation in a southern California desert habitat

USDA-ARS?s Scientific Manuscript database

Treating perimeters with residual insecticides to provide protection from mosquito vectors has shown promise. These barrier treatments are typically evaluated in temperate or tropical areas using lush, ambient vegetation as a substrate for the pesticide. However, there is an emerging interest to dev...

Habitat improvement for wildlife in North-Central Sonora, Mexico

Treesearch

Martha Martin-Rivera; Fernando Ibarra-Flores; Fred S. Guthery; William P. Kublesky; Gustavo Camou-Luders; Jesus Fimbres-Preciado; Donald Johnson-Gordon

2001-01-01

Native vegetation of semiarid grasslands and desert ecosystems that comprise the Arbosufrutescent Desert scrub vegetation in north-central Sonora has been degraded by overgrazing, drought, farming, woodcutting, and a host of other activities over the past century. Several studies were conducted at "Rancho Grande" and at "Rancho El Carrizo," Sonora...

Chalk Point cooling tower project native vegetation study. Final report 1979

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

Patterson, G.W.; Galloway, R.A.; Francis, B.A.

1979-06-01

The Potomac Electric Power Company generating station at Chalk Point, MD, utilizes brackish water in its natural draft cooling tower and, consequently, releases saline aerosol into the atmosphere. A research and monitoring project was established in 1974 to evaluate the effects of this drift on native perennial vegetation. Leaf samples have been collected form dogwood, Cornys florida, Virginia pine, Pinus virginiana, black locust, Robinia pseudoacacia, and sassafras, Sassafras albidum, located at 12 different sites in the vicinity of the power plant. Sampling was begun prior to the operation of the cooling tower, 1974, and continued through 1978. Complete results frommore » monthly monitoring of foliar chloride in the four native tree species is documented for May through September 1978. Results from salt spray experiments indicate chloride and sodium concentrations in the wood of dogwood trees increases with increased spraying levels.« less

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.

Facilitation and interference of seedling establishment by a native legume before and after wildfire

Treesearch

Erin Goergen; Jeanne C. Chambers

2011-01-01

In semi-arid ecosystems, heterogeneous resources can lead to variable seedling recruitment. Existing vegetation can influence seedling establishment by modifying the resource and physical environment. We asked how a native legume, Lupinus argenteus, modifies microenvironments in unburned and burned sagebrush steppe, and if L. argenteus presence facilitates seedling...

Molecular survey for the invasive leafminer pest Liriomyza Huidobrensis in California (Diptera: Agromyzidae) uncovers only the native pest L. langei

USDA-ARS?s Scientific Manuscript database

Liriomyza huidobrensis is a highly destructive invasive leafminer pest currently causing extensive damage to vegetable and horticultural crops around the world. Liriomyza langei is a leafminer pest native to California that cannot currently be morphologically distinguished from L. huidobrensis. This...

Methods for increasing biodiversity in wetland creation and restoration efforts

Treesearch

Ross Coleman

1999-01-01

Many wetland creation and restoration projects have successfully restored or created appropriate hydrologic conditions for the support of wetland ecosystems but have not been as successful in establishing a diverse biota of native wetland vegetation. Recent work in the propagation and transplanting of native wetland plant seedlings offers promise for increasing...

Prospects for biological control of Cape-ivy with the Cape-ivy fly and the cape-ivy moth

USDA-ARS?s Scientific Manuscript database

Cape-ivy (Delairea odorata, Asteraceae), native to coastal floodplains and mountain riparian zones in eastern South Africa, is an invasive vine in coastal riparian, woodland and scrub habitats in California and southern Oregon. Cape-ivy smothers native vegetation and may impair water flow in coastal...

Terrace aggradation during the 1978 flood on Powder River, Montana, USA

USGS Publications Warehouse

Moody, J.A.; Meade, R.H.

2008-01-01

Flood processes no longer actively increase the planform area of terraces. Instead, lateral erosion decreases the area. However, infrequent extreme floods continue episodic aggradation of terraces surfaces. We quantify this type of evolution of terraces by an extreme flood in May 1978 on Powder River in southeastern Montana. Within an 89-km study reach of the river, we (1) determine a sediment budget for each geomorphic feature, (2) interpret the stratigraphy of the newly deposited sediment, and (3) discuss the essential role of vegetation in the depositional processes. Peak flood discharge was about 930??m3 s- 1, which lasted about eight??days. During this time, the flood transported 8.2??million tons of sediment into and 4.5??million tons out of the study reach. The masses of sediment transferred between features or eroded from one feature and redeposited on the same feature exceeded the mass transported out of the reach. The flood inundated the floodplain and some of the remnants of two terraces along the river. Lateral erosion decreased the planform area of the lower of the two terraces (~ 2.7??m above the riverbed) by 3.2% and that of the higher terrace (~ 3.5??m above the riverbed) by 4.1%. However, overbank aggradation, on average, raised the lower terrace by 0.16??m and the higher terrace by 0.063??m. Vegetation controlled the type, thickness, and stratigraphy of the aggradation on terrace surfaces. Two characteristic overbank deposits were common: coarsening-upward sequences and lee dunes. Grass caused the deposition of the coarsening-upward sequences, which had 0.02 to 0.07??m of mud at the base, and in some cases, the deposits coarsened upwards to coarse sand on the top. Lee dunes, composed of fine and very fine sand, were deposited in the wake zone downstream from the trees. The characteristic morphology of the dunes can be used to estimate some flood variables such as suspended-sediment particle size, minimum depth, and critical shear velocity. Information about depositional processes during extreme floods is rare, and therefore, the results from this study aid in interpreting the record of terrace stratigraphy along other rivers.

Inventory of native vegetation and related resources from space photography

NASA Technical Reports Server (NTRS)

Poulton, C. E.; Johnson, J. R.; Mouat, D. A.

1970-01-01

The application of space and high flight photography to vegetational resources in Arizona is discussed. Ecologically based vegetation-landform and land use maps are prepared. The use of material from the Apollo 9 flight and high flight aerial photography are discussed. Land uses that result in a conversion or strong modification of the natural vegetation are presented. The vegetation-landform units have an ecological basis and are meaningful from a land use point of view because they identify areas with unique potentials or limitations for use or development under various land uses. Examples of these relationships are given.

SAR Polarimetry

NASA Technical Reports Server (NTRS)

vanZyl, Jakob J.

2012-01-01

Radar Scattering includes: Surface Characteristics, Geometric Properties, Dielectric Properties, Rough Surface Scattering, Geometrical Optics and Small Perturbation Method Solutions, Integral Equation Method, Magellan Image of Pancake Domes on Venus, Dickinson Impact Crater on Venus (Magellan), Lakes on Titan (Cassini Radar, Longitudinal Dunes on Titan (Cassini Radar), Rough Surface Scattering: Effect of Dielectric Constant, Vegetation Scattering, Effect of Soil Moisture. Polarimetric Radar includes: Principles of Polarimetry: Field Descriptions, Wave Polarizations: Geometrical Representations, Definition of Ellipse Orientation Angles, Scatter as Polarization Transformer, Scattering Matrix, Coordinate Systems, Scattering Matrix, Covariance Matrix, Pauli Basis and Coherency Matrix, Polarization Synthesis, Polarimeter Implementation.

High N, dry: Experimental nitrogen deposition exacerbates native shrub loss and nonnative plant invasion during extreme drought.

PubMed

Valliere, Justin M; Irvine, Irina C; Santiago, Louis; Allen, Edith B

2017-10-01

Hotter, longer, and more frequent global change-type drought events may profoundly impact terrestrial ecosystems by triggering widespread vegetation mortality. However, severe drought is only one component of global change, and ecological effects of drought may be compounded by other drivers, such as anthropogenic nitrogen (N) deposition and nonnative plant invasion. Elevated N deposition, for example, may reduce drought tolerance through increased plant productivity, thereby contributing to drought-induced mortality. High N availability also often favors invasive, nonnative plant species, and the loss of woody vegetation due to drought may create a window of opportunity for these invaders. We investigated the effects of multiple levels of simulated N deposition on a Mediterranean-type shrubland plant community in southern California from 2011 to 2016, a period coinciding with an extreme, multiyear drought in the region. We hypothesized that N addition would increase native shrub productivity, but that this would increase susceptibility to drought and result in increased shrub loss over time. We also predicted that N addition would favor nonnatives, especially annual grasses, leading to higher biomass and cover of these species. Consistent with these hypotheses, we found that high N availability increased native shrub canopy loss and mortality, likely due to the higher productivity and leaf area and reduced water-use efficiency we observed in shrubs subject to N addition. As native shrub cover declined, we also observed a concomitant increase in cover and biomass of nonnative annuals, particularly under high levels of experimental N deposition. Together, these results suggest that the impacts of extended drought on shrubland ecosystems may be more severe under elevated N deposition, potentially contributing to the widespread loss of native woody species and vegetation-type conversion. © 2017 John Wiley & Sons Ltd.

Alien plant invasion in mixed-grass prairie: effects of vegetation type, stochiasticity, and anthropogenic disturbance in two park units

USGS Publications Warehouse

Larson, Diane L.; Anderson, Patrick J.; Newton, Wesley E.

2001-01-01

The ability of alien plant species to invade a region depends not only on attributes of the plant, but on characteristics of the habitat being invaded. Here, we examine characteristics that may influence the success of alien plant invasion in mixed-grass prairie at Theodore Roosevelt National Park, in western North Dakota, USA. The park consists of two geographically separate units with similar vegetation types and management history, which allowed us to examine the effects of native vegetation type, anthropogenic disturbance, and the separate park units on the invasion of native plant communities by alien plant species common to counties surrounding both park units. If matters of chance related to availability of propagules and transient establishment opportunities determine the success of invasion, park unit and anthropogenic disturbance should better explain the variation in alien plant frequency. If invasibility is more strongly related to biotic or physical characteristics of the native plant communities, models of alien plant occurrence should include vegetation type as an explanatory variable. We examined >1300 transects across all vegetation types in both units of the park. Akaike's Information Criterion (AIC) indicated that the fully parameterized model, including the interaction among vegetation type, disturbance, and park unit, best described the distribution of both total number of alien plants per transect and frequency of alien plants on transects where they occurred. Although all vegetation types were invaded by alien plants, mesic communities had both greater numbers and higher frequencies of alien plants than did drier communities. A strong element of stochasticity, reflected in differences in frequencies of individual species between the two park units, suggests that prediction of risk of invasion will always involve uncertainty. In addition, despite well-documented associations between anthropogenic disturbance and alien plant invasion, five of the six most abundant alien species at Theodore Roosevelt National Park had distributions unrelated to disturbance. We recommend that vegetation type be explicitly taken into account when designing monitoring plans for alien species in natural areas.

Late-Quaternary vegetation history at White Pond on the inner Coastal Plain of South Carolina*1

NASA Astrophysics Data System (ADS)

Watts, W. A.

1980-03-01

At White Pond near Columbia, South Carolina, a pollen assemblage of Pinus banksiana (jack pine), Picea (spruce), and herbs is dated between 19,100 and 12,800 14C yr B.P. Plants of sandhill habitats are more prominent than at other sites of similar age, and pollen of deciduous trees is infrequent. The vegetation was probably a mosaic of pine and spruce stands with prairies and sand-dune vegetation. The climate may have been like that of the eastern boreal forest today. 14C dates of 12,800 and 9500 yr B.P. bracket a time when Quercus (oak), Carya (hickory), Fagus (beech), and Ostrya-Carpinus (ironwood) dominated the vegetation. It is estimated that beech and hickory made up at least 25% of the forest trees. Conifers were rare or absent. The environment is interpreted as hickory-rich mesic deciduous forest with a climate similar to but slightly warmer than that of the northern hardwoods region of western New York State. After 9500 yr B.P. oak and pine forest dominated the landscape, with pine becoming the most important tree genus in the later Holocene.

Central Aleutian tundra: ecological manifestations of maritime tundra landscapes in the Central Aleution Islands (Amchitka, Adak) Alaska. Final report, 1 April 1971-15 November 1985

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

Amundsen, C.C.

1985-01-01

Measured and inferred ecological characteristics and holocoenotic factors which affect the dynamics and manifestations of central Aleutian maritime tundra and beach-dune vegetational expressions of Adak and Amchitka Islands are discussed. The known vascular flora is enumerated and predominant taxa are grouped into communities and topoedaphic units. Stability of community composition and structure is elaborated and the absence of ecological succession demonstrated. Perturbations occasioned by human activities which impinge on these remote islands are detailed. The testing and monitoring of subsequent passive and managed recovery of stable vegetation on disturbed areas is described. Selection, preparation and utilization of transplants of Elymusmore » mollis Trin. is documented. Transplants of rhizomes of E. mollis are successful in the reestablishment of vegetative cover in disturbed habitats which are topoedaphically suitable for graminoid success. The responses of plant population stands to environmental processes and habitat insults are reported. The relatively limited but stable biota and the lethargic ecological response as defined by extant vegetational expressions provide field test potentials which mandate further basic and applied research.« less

An invasive clonal plant benefits from clonal integration more than a co-occurring native plant in nutrient-patchy and competitive environments.

PubMed

You, Wenhua; Fan, Shufeng; Yu, Dan; Xie, Dong; Liu, Chunhua

2014-01-01

Many notorious invasive plants are clonal, however, little is known about the different roles of clonal integration effects between invasive and native plants. Here, we hypothesize that clonal integration affect growth, photosynthetic performance, biomass allocation and thus competitive ability of invasive and native clonal plants, and invasive clonal plants benefit from clonal integration more than co-occurring native plants in heterogeneous habitats. To test these hypotheses, two stoloniferous clonal plants, Alternanthera philoxeroides (invasive), Jussiaea repens (native) were studied in China. The apical parts of both species were grown either with or without neighboring vegetation and the basal parts without competitors were in nutrient- rich or -poor habitats, with stolon connections were either severed or kept intact. Competition significantly reduced growth and photosynthetic performance of the apical ramets in both species, but not the biomass of neighboring vegetation. Without competition, clonal integration greatly improved the growth and photosynthetic performance of both species, especially when the basal parts were in nutrient-rich habitats. When grown with neighboring vegetation, growth of J. repens and photosynthetic performance of both species were significantly enhanced by clonal integration with the basal parts in both nutrient-rich and -poor habitats, while growth and relative neighbor effect (RNE) of A. philoxeroides were greatly improved by clonal integration only when the basal parts were in nutrient-rich habitats. Moreover, clonal integration increased A. philoxeroides's biomass allocation to roots without competition, but decreased it with competition, especially when the basal ramets were in nutrient-rich sections. Effects of clonal integration on biomass allocation of J. repens was similar to that of A. philoxeroides but with less significance. These results supported our hypothesis that invasive clonal plants A. philoxeroides benefits from clonal integration more than co-occurring native J. repens, suggesting that the invasiveness of A. philoxeroides may be closely related to clonal integration in heterogeneous environments.

Plant species invasions along the latitudinal gradient in the United States

USGS Publications Warehouse

Stohlgren, T.J.; Barnett, D.; Flather, C.; Kartesz, J.; Peterjohn, B.

2005-01-01

It has been long established that the richness of vascular plant species and many animal taxa decreases with increasing latitude, a pattern that very generally follows declines in actual and potential evapotranspiration, solar radiation, temperature, and thus, total productivity. Using county-level data on vascular plants from the United States (3000 counties in the conterminous 48 states), we used the Akaike Information Criterion (AIC) to evaluate competing models predicting native and nonnative plant species density (number of species per square kilometer in a county) from various combinations of biotic variables (e.g., native bird species density, vegetation carbon, normalized difference vegetation index), environmental/topographic variables (elevation, variation in elevation, the number of land cover classes in the county; radiation, mean precipitation, actual evapotranspiration, and potential evapotranspiration), and human variables (human population density, crop-land, and percentage of disturbed lands in a county). We found no evidence of a latitudinal gradient for the density of native plant species and a significant, slightly positive latitudinal gradient for the density of nonnative plant species. We found stronger evidence of a significant, positive productivity gradient (vegetation carbon) for the density of native plant species and nonnative plant species. We found much stronger significant relationships when biotic, environmental/topographic, and human variables were used to predict native plant species density and nonnative plant species density. Biotic variables generally had far greater influence in multivariate models than human or environmental/topographic variables. Later, we found that the best, single, positive predictor of the density of nonnative plant species in a county was the density of native plant species in a county. While further study is needed, it may be that, while humans facilitate the initial establishment invasions of nonnative plant species, the spread and subsequent distributions of nonnative species are controlled largely by biotic and environmental factors.

An Invasive Clonal Plant Benefits from Clonal Integration More than a Co-Occurring Native Plant in Nutrient-Patchy and Competitive Environments

PubMed Central

You, Wenhua; Fan, Shufeng; Yu, Dan; Xie, Dong; Liu, Chunhua

2014-01-01

Many notorious invasive plants are clonal, however, little is known about the different roles of clonal integration effects between invasive and native plants. Here, we hypothesize that clonal integration affect growth, photosynthetic performance, biomass allocation and thus competitive ability of invasive and native clonal plants, and invasive clonal plants benefit from clonal integration more than co-occurring native plants in heterogeneous habitats. To test these hypotheses, two stoloniferous clonal plants, Alternanthera philoxeroides (invasive), Jussiaea repens (native) were studied in China. The apical parts of both species were grown either with or without neighboring vegetation and the basal parts without competitors were in nutrient- rich or -poor habitats, with stolon connections were either severed or kept intact. Competition significantly reduced growth and photosynthetic performance of the apical ramets in both species, but not the biomass of neighboring vegetation. Without competition, clonal integration greatly improved the growth and photosynthetic performance of both species, especially when the basal parts were in nutrient-rich habitats. When grown with neighboring vegetation, growth of J. repens and photosynthetic performance of both species were significantly enhanced by clonal integration with the basal parts in both nutrient-rich and -poor habitats, while growth and relative neighbor effect (RNE) of A. philoxeroides were greatly improved by clonal integration only when the basal parts were in nutrient-rich habitats. Moreover, clonal integration increased A. philoxeroides's biomass allocation to roots without competition, but decreased it with competition, especially when the basal ramets were in nutrient-rich sections. Effects of clonal integration on biomass allocation of J. repens was similar to that of A. philoxeroides but with less significance. These results supported our hypothesis that invasive clonal plants A. philoxeroides benefits from clonal integration more than co-occurring native J. repens, suggesting that the invasiveness of A. philoxeroides may be closely related to clonal integration in heterogeneous environments. PMID:24816849

Analysis of beach morphodynamics on the Bragantinian mangrove peninsula (Pará, North Brazil) as prerequisite for coastal zone management recommendations

NASA Astrophysics Data System (ADS)

Krause, Gesche; Soares, Cidiane

2004-05-01

A beach profile monitoring programme was initiated in 1997 as a contribution to the development of recommendations for an integrated coastal zone management scheme of the mangrove peninsula of Bragança, State of Pará (North Brazil). It was the first scientific investigation on the coastal morphodynamics in a mangrove environment, which was opened for human use only since the mid-1970s. The observations were carried out on five sections for 4 years, on a fortnightly basis whenever possible. Temporal evolution of the beach morphology was assessed using time series of beach height, changes in profile shape, sediment transport calculations, and photographs. This unique data set for new settlement areas in this mangrove-dominated coastal zone illuminates the role of the interaction between human activities and natural coastal dynamics. Four coastal cells were identified as coastal management units, each with specific dynamic behaviour and utilisation by humans. The cells are rather small with dimensions in the order of 1-3 km. Only one of the units (cell 1) had a stable coastline during the 4 years of observation, while all others are eroding. Clearing of vegetation is the principal reason for the enhancement of the natural chronic erosion at these sites. In the wake of increasing tourism, housing was erected on the first dune ridge (cell 2) with much damage to the natural vegetation. In this unit, erosion is predominantly targeted on the dunes. In cell 3, the most important reason for the increased erosion is clearing of the adjacent fringing mangroves. This is also true for cell 4, but additionally the construction of large fishing traps, which artificially entrap sand and create sandbanks and thereby increase velocities in the tidal channel tend to enhance erosion at the shoreline. Only for cell 1 can protection measures for the still available vegetation be recommended while a planned retreat of many tourism facilities and fishermen's housings should be included in management recommendations.

Long-term Water Table Monitoring of Rio Grande Riparian Ecosystems for Restoration Potential Amid Hydroclimatic Challenges.

PubMed

Thibault, James R; Cleverly, James R; Dahm, Clifford N

2017-12-01

Hydrological processes drive the ecological functioning and sustainability of cottonwood-dominated riparian ecosystems in the arid southwestern USA. Snowmelt runoff elevates groundwater levels and inundates floodplains, which promotes cottonwood germination. Once established, these phreatophytes rely on accessible water tables (WTs). In New Mexico's Middle Rio Grande corridor diminished flooding and deepening WTs threaten native riparian communities. We monitored surface flows and riparian WTs for up to 14 years, which revealed that WTs and surface flows, including peak snowmelt discharge, respond to basin climate conditions and resource management. WT hydrographs influence the composition of riparian communities and can be used to assess if potential restoration sites meet native vegetation tolerances for WT depths, rates of recession, and variability throughout their life stages. WTs were highly variable in some sites, which can preclude native vegetation less adapted to deep drawdowns during extended droughts. Rates of WT recession varied between sites and should be assessed in regard to recruitment potential. Locations with relatively shallow WTs and limited variability are likely to be more viable for successful restoration. Suitable sites have diminished greatly as the once meandering Rio Grande has been constrained and depleted. Increasing demands on water and the presence of invasive vegetation better adapted to the altered hydrologic regime further impact native riparian communities. Long-term monitoring over a range of sites and hydroclimatic extremes reveals attributes that can be evaluated for restoration potential.

Long-term Water Table Monitoring of Rio Grande Riparian Ecosystems for Restoration Potential Amid Hydroclimatic Challenges

NASA Astrophysics Data System (ADS)

Thibault, James R.; Cleverly, James R.; Dahm, Clifford N.

2017-12-01

Hydrological processes drive the ecological functioning and sustainability of cottonwood-dominated riparian ecosystems in the arid southwestern USA. Snowmelt runoff elevates groundwater levels and inundates floodplains, which promotes cottonwood germination. Once established, these phreatophytes rely on accessible water tables (WTs). In New Mexico's Middle Rio Grande corridor diminished flooding and deepening WTs threaten native riparian communities. We monitored surface flows and riparian WTs for up to 14 years, which revealed that WTs and surface flows, including peak snowmelt discharge, respond to basin climate conditions and resource management. WT hydrographs influence the composition of riparian communities and can be used to assess if potential restoration sites meet native vegetation tolerances for WT depths, rates of recession, and variability throughout their life stages. WTs were highly variable in some sites, which can preclude native vegetation less adapted to deep drawdowns during extended droughts. Rates of WT recession varied between sites and should be assessed in regard to recruitment potential. Locations with relatively shallow WTs and limited variability are likely to be more viable for successful restoration. Suitable sites have diminished greatly as the once meandering Rio Grande has been constrained and depleted. Increasing demands on water and the presence of invasive vegetation better adapted to the altered hydrologic regime further impact native riparian communities. Long-term monitoring over a range of sites and hydroclimatic extremes reveals attributes that can be evaluated for restoration potential.

Late Holocene fire and vegetation reconstruction from the western Klamath Mountains, California, USA: a multi-disciplinary approach for examining potential human land-use impacts

Treesearch

J. N. Crawford; S. A. Mensing; Frank Lake; S. R. Zimmerman

2015-01-01

The influence of Native American land-use practices on vegetation composition and structure has long been a subject of significant debate. This is particularly true in portions of the western United States where tribal hunter-gatherers did not use agriculture to meet subsistence and other cultural needs. Climate has been viewed as the dominant determinant of vegetation...

Chronology and geochemistry of late Holocene eolian deposits in the Brandon Sand Hills, Manitoba, Canada

USGS Publications Warehouse

Wolfe, S.A.; Muhs, D.R.; David, P.P.; McGeehin, J.P.

2000-01-01

Accelerator mass spectrometry and conventional radiocarbon age determinations of organic matter from paleosols indicate that the Brandon Sand Hills area of southern Manitoba has been subjected to recurrent intervals of eolian activity in the past 5000 years. Although precise regional correlations are precluded by dating uncertainties, periods of most notable paleosol development occurred around 2300 to 2000, 1400 to 1000, and 600 to 500 cal yr BP with eolian activity occurring before and after each of these periods. Episodes of eolian activity may correspond to periods of regional drought, whereas paleosols mark periods of increased moisture availability and stabilization by vegetation. The geochemistry of the eolian sands, paleosols and source sediments indicates that partial leaching of carbonates occurs from pedogenesis during humid climatic phases, and that this is probably the primary mechanism of carbonate depletion of eolian sands in this area. Recent trends in sand dune activity from historic aerial photography and early explorers' accounts indicate that the few active dunes that presently exist have stabilized at a rate of 10-20% per decade, despite several severe droughts in the 20th century. This may be attributed to pre-settlement droughts that were more severe than those in historic times although regional dune stabilization may also be related, in part, to the spread of forest cover in the past few hundred years. Crown copyright (C) 2000 Published by Elsevier Science Ltd. All rights reserved.

Fungal symbiosis and precipitation alter traits and dune building by the ecosystem engineer, Ammophila breviligulata.

PubMed

Emery, Sarah M; Bell-Dereske, Lukas; Rudgers, Jennifer A

2015-04-01

Ecosystem engineer species influence their community and ecosystem by creating or altering the physical structure of habitats. The function of ecosystem engineers is variable and can depend on both abiotic and biotic factors. Here we make use of a primary successional system to evaluate the direct and interactive effects of climate change (precipitation) and fungal endophyte symbiosis on population traits and ecosystem function of the ecosystem engineering grass species, Ammophila breviligulata. We manipulated endophyte presence in A. breviligulata in combination with rain-out shelters and rainfall additions in a factorial field experiment established in 2010 on Lake Michigan sand dunes. We monitored plant traits, survival, growth, and sexual reproduction of A. breviligulata from 2010-2013, and quantified ecosystem engineering as the sand accumulation rate. Presence of the endophyte in A. breviligulata increased vegetative growth by up to 19%, and reduced sexual reproduction by up to 46% across all precipitation treatments. Precipitation was a less significant factor than endophyte colonization for A. breviligulata growth. Reduced precipitation increased average leaf number per tiller but had no other effects on plant traits. Changes in A. breviligulata traits corresponded to increases in sand accumulation in plots with the endophyte as well as in plots with reduced precipitation. Sand accumulation is a key ecosystem function in these primary successional habitats, and so microbial symbiosis in this ecosystem engineer could lead to direct effects on the value of these dune habitats for humans.

Sand fences in the coastal zone: intended and unintended effects.

PubMed

Grafals-Soto, Rosana; Nordstrom, Karl

2009-09-01

Sand-trapping fences modify the character of the coastal landscape and change its spatial structure, image, and meaning. This paper examines the relationship between these changes and fence usage at the municipal level, where most decisions about fence deployment are made. Use of fences in 29 municipalities on the developed coast of New Jersey is examined over a 6-year period. Interviews with municipal officers indicate that wooden slat sand-trapping fences are used primarily to build dunes to provide protection against wave uprush and flooding, but they are also used to control pedestrian traffic and demarcate territory. These uses result in changes in landforms and habitats. An aerial video inventory of fences taken in 2002 indicates that 82% of the shoreline had fences and 72% had dunes. Single and double straight fence rows are the most commonly used. Fences are often built to accomplish a specific primary purpose, but they can cause many different and often unanticipated changes to the landscape. The effects of a sand fence change through time as the initial structure traps sand, creates a dune that is colonized by vegetation, and becomes integrated into the environment by increasing topographic variability and aesthetic and habitat value. Sand fences can be made more compatible with natural processes by not placing them in locations where sources of wind blown sand are restricted or in unnatural shore perpendicular orientations. Symbolic fences are less expensive, are easy to replace when damaged, are less visually intrusive, and can be used for controlling pedestrian access.

Radar remote sensing of wind-driven land degradation processes in northeastern Patagonia.

PubMed

del Valle, H F; Blanco, P D; Metternicht, G I; Zinck, J A

2010-01-01

Wind-driven land degradation negatively impacts on rangeland production and infrastructure in the Valdes Peninsula, northeastern Patagonia. The Valdes Peninsula has the most noticeable dunefields of the Patagonian drylands. Wind erosion has been assessed at different scales in this region, but often with limited data. In general, terrain features caused by wind activity are better discriminated by active microwaves than by sensors operating in the visible and infrared regions of the electromagnetic spectrum. This paper aims to analyze wind-driven land degradation processes that control the radar backscatter observed in different sources of radar imagery. We used subsets derived from SIR-C, ERS-1 and 2, ENVISAT ASAR, RADARSAT-1, and ALOS PALSAR data. The visibility of aeolian features on radar images is mostly a function of wavelength, polarization, and incidence angle. Stabilized sand deposits are clearly observed in radar images, with defined edges but also signals of ongoing wind erosion. One of the most conspicuous features corresponds to old track sand dunes, a mixture of active and inactive barchanoid ridges and parabolic dunes. This is a clear example of deactivation of migrating dunes under the influence of vegetation. The L-band data reveal details of these sand ridges, whereas the C-band data only allow detecting a few of the larger tracks. The results of this study enable us to make recommendations about the utility of some radar sensor configurations for wind-driven land degradation reconnaissance in mid-latitude regions.

Recreational trails as corridors for alien plants in the Rocky Mountains, USA

USGS Publications Warehouse

Wells, Floye H.; Lauenroth, William K.; Bradford, John B.

2012-01-01

Alien plant species often use areas of heavy human activity for habitat and dispersal. Roads and utility corridors have been shown to harbor more alien species than the surrounding vegetation and are therefore believed to contribute to alien plant persistence and spread. Recreational trails represent another corridor that could harbor alien species and aid their spread. Effective management of invasive species requires understanding how alien plants are distributed at trailheads and trails and how their dispersal may be influenced by native vegetation. Our overall goal was to investigate the distribution of alien plants at trailheads and trails in the Rocky Mountains of Colorado. At trailheads, we found that although the number of alien species was less than the number of native species, alien plant cover ( x̄=50%) did not differ from native plant cover, and we observed a large number of alien seedlings in the soil seed bank, suggesting that alien plants are a large component of trailhead communities and will continue to be so in the future. Along trails, we found higher alien species richness and cover on trail (as opposed to 4 m from the trail) in 3 out of 4 vegetation types, and we observed higher alien richness and cover in meadows than in other vegetation types. Plant communities at both trailheads and trails, as well as seed banks at trailheads, contain substantial diversity and abundance of alien plants. These results suggest that recreational trails in the Rocky Mountains of Colorado may function as corridors that facilitate the spread of alien species into wildlands. Our results suggest that control of alien plants should begin at trailheads where there are large numbers of aliens and that control efforts on trails should be prioritized by vegetation type.

Reintroduction of locally extinct vertebrates impacts arid soil fungal communities.

PubMed

Clarke, Laurence J; Weyrich, Laura S; Cooper, Alan

2015-06-01

Introduced species have contributed to extinction of native vertebrates in many parts of the world. Changes to vertebrate assemblages are also likely to alter microbial communities through coextinction of some taxa and the introduction of others. Many attempts to restore degraded habitats involve removal of exotic vertebrates (livestock and feral animals) and reintroduction of locally extinct species, but the impact of such reintroductions on microbial communities is largely unknown. We used high-throughput DNA sequencing of the fungal internal transcribed spacer I (ITS1) region to examine whether replacing exotic vertebrates with reintroduced native vertebrates led to changes in soil fungal communities at a reserve in arid central Australia. Soil fungal diversity was significantly different between dune and swale (interdune) habitats. Fungal communities also differed significantly between sites with exotic or reintroduced native vertebrates after controlling for the effect of habitat. Several fungal operational taxonomic units (OTUs) found exclusively inside the reserve were present in scats from reintroduced native vertebrates, providing a direct link between the vertebrate assemblage and soil microbial communities. Our results show that changes to vertebrate assemblages through local extinctions and the invasion of exotic species can alter soil fungal communities. If local extinction of one or several species results in the coextinction of microbial taxa, the full complement of ecological interactions may never be restored. © 2015 John Wiley & Sons Ltd.

Understory vegetation response to mechanical mastication and other fuels treatments in a ponderosa pine forest

Treesearch

Jeffrey M. Kane; J. Morgan Varner; Eric E. Knapp

2010-01-01

Questions: What influence does mechanical mastication and other fuel treatments have on: (1) canopy and forest floor response variables that influence understory plant development; (2) initial understory vegetation cover, diversity, and composition; and (3) shrub and non-native species density in a secondgrowth ponderosa pine forest....

Wildfire, Exotic Vegetation, and Breeding Bird Habitat in the Rio Grande Bosque

Treesearch

D. Max Smith; Jeff F. Kelly; Deborah M. Finch

2006-01-01

Wildfires in the Middle Rio Grande bosque have likely increased in frequency due to absence of the natural flood regime and current drought conditions. Native cottonwoods (Populus spp.) do not tolerate or recover from wildfire as well as exotic vegetation, particularly salt cedar, also known as tamarisk (Tamarix spp.). There is...

Effects of native vegetation on invasion success of Chinese tallow in a floating marsh ecosystem

Treesearch

L.L. Battaglia; J.S. Denslow; J.R. Inczauskis; S.G. Baer

2009-01-01

Interactions between resident and exotic species have been shown to control the biotic resistance of communities to invasion. With different life stages of the exotic species, each sequential interaction may dampen or strengthen previous ones, thereby influencing invasion success.We assessed the effects of resident vegetation type on...

RESEARCH REPORT: USE OF VEGETATIVE VIGOR TEST TO DETECT EFFECTS OF LOW LEVELS OF HERBICIDES ON SELECTED NON-CROP PLANTS

EPA Science Inventory

To address the need for improved phytotoxicity testing protocols, we evaluated use of the vegetative vigor test methodology for use in determining effects of low concentrations of chemical herbicides on terrestrial non-crop plant species. Species included native plants from Illi...

Chapter 29. Production and use of planting stock

Treesearch

Nancy L. Shaw

2004-01-01

Vegetation can be rapidly established on disturbed sites by planting stock alone or in combination with direct seedings. Types of planting stock commonly used range from bareroot or containerized seedlings to pads of native vegetation. Inclusion of planting stock in rehabilitation or restoration projects requires careful scheduling, selection of adapted plant species,...

Depressional wetland vegetation types: a question of plant commmunity development

Treesearch

Katherine L. Kirkman; Charles P. Goebel; Larry West; Mark B. Drew; Brian Palik

2000-01-01

When wetland restoration includes re-establishing native plant taxa as an objective, an understanding of the variables driving the development of plant communities is necessary. With this in mind, we examined soil and physiographic characteristics of depressional wetlands of three vegetation types (cypressgum swamps, cypress savannas, and grass-sedge marshes) located...

Post-wildfire seeding to restore native vegetation and limit exotic annuals: an evaluation in juniper-dominated sagebrush steppe

USDA-ARS?s Scientific Manuscript database

Reestablishment of perennial vegetation is often need after wildfires to limit exotic species and restore ecosystem services. Some ecosystems, however, are resilient to disturbance and resistant to exotic plant invasions and do not require restoration efforts. If restoration is needed, an addition...

Vegetative propagation [Chapter 9

Treesearch

Tara Luna

2009-01-01

For the past 30 years, interest in the propagation of native plants has been growing. Many desirable and ecologically important species, however, are difficult or very time consuming to propagate by seeds. Thus, nursery growers may want to investigate how to propagate a species of interest by vegetative propagation. This can be done by combining classic horticultural...

Impacts of exotic mangroves and mangrove control on tide pool fish assemblages

Treesearch

Richard A. MacKenzie; Cailtin L. Kryss

2013-01-01

Fish were sampled from tide pools in Hawaii to determine how exotic mangroves Rhizophora mangle and the use of herbicides to chemically eradicate them are impacting tide pool fish assemblages. Ecological parameters were compared among mangrove-invaded, native vegetated, and non-vegetated tide pools before and after mangroves had been chemically...

Using urban forest assessment tools to model bird habitat potential

Treesearch

Susannah B. Lerman; Keith H. Nislow; David J. Nowak; Stephen DeStefano; David I. King; D. Todd Jones-Farrand

2014-01-01

The alteration of forest cover and the replacement of native vegetation with buildings, roads, exotic vegetation, and other urban features pose one of the greatest threats to global biodiversity. As more land becomes slated for urban development, identifying effective urban forest wildlife management tools becomes paramount to ensure the urban forest provides habitat...

18 CFR 1304.203 - Vegetation management.

Code of Federal Regulations, 2011 CFR

2011-04-01

... located to minimize removal of trees or other vegetation on the TVA land. (d) Grass may be planted and... ground level is allowed. (h) Removal of trees outside of the access corridor but within the SMZ may be... corridor. (k) Planting of trees, shrubs, wildflowers, native grasses, and ground covers within the SMZ is...

18 CFR 1304.203 - Vegetation management.

Code of Federal Regulations, 2010 CFR

2010-04-01

... located to minimize removal of trees or other vegetation on the TVA land. (d) Grass may be planted and... ground level is allowed. (h) Removal of trees outside of the access corridor but within the SMZ may be... corridor. (k) Planting of trees, shrubs, wildflowers, native grasses, and ground covers within the SMZ is...

Historic vegetation changes in Lincoln County, New Mexico: The Albuquerque Banquet Presentation

Treesearch

E. Hollis Fuchs

2008-01-01

(Please note, this is an abstract only) Repeat photography will demonstrate that since European settlement commenced, the native vegetation of Lincoln County, New Mexico has dramatically changed. Numerous historic photographs have been re-taken, demonstrating how landscapes and ecosystems have changed, not just between early European settlement until the present, but...

Stars and linear dunes on Mars

NASA Technical Reports Server (NTRS)

Edgett, Kenneth S.; Blumberg, Dan G.

1994-01-01

A field containing 11 star and incipient star dunes occurs on Mars at 8.8 deg S, 270.9 deg W. Examples of linear dunes are found in a crater at 59.4 deg S, 343 deg W. While rare, dune varieties that form in bi- and multidirectional wind regimes are not absent from the surface of Mars. The occurence of both of these dune fields offers new insight into the nature of martian wind conditions and sand supply. The linear dunes appears to have formed through modification of a formerly transverse aeolian deposit, suggesting a relatively recent change in local wind direction. The 11 dunes in the star dune locality show a progressive change from barchan to star form as each successive dune has traveled up into a valley, into a more complex wind regime. The star dunes corroborate the model of N. Lancaster (1989), for the formation of star dunes by projection of transverse dunes into a complex, topographically influenced wind regime. The star dunes have dark streaks emanating from them, providing evidence that the dunes were active at or near the time the relevant image was obtained by the Viking 1 orbiter in 1978. The star and linear dunes described here are located in different regions on the martian surface. Unlike most star and linear dunes on Earth, both martian examples are isolated occurrences; neither is part of a major sand sea. Previously published Mars general circulation model results suggest that the region in which the linear dune field occurs should be a bimodal wind regime, while the region in which the star dunes occur should be unimodal. The star dunes are probably the result of localized complication of the wind regime owing to topographic confinement of the dunes. Local topographic influence on wind regime is also evident in the linear dune field, as there are transverse dunes in close proximity to the linear dunes, and their occurrence is best explained by funneling of wind through a topographic gap in the upwind crater wall.

River flooding and its impacts on large-scale biocontrol of Tamarix in the Colorado and Virgin River system: Moving targets and trajectories

USDA-ARS?s Scientific Manuscript database

Along riparian corridors throughout the arid and semiarid regions of the western United States, non-native shrubs and trees in the genus Tamarix have replaced native vegetation. Plant communities along rivers with altered flow regimes and flood control have become particularly vulnerable to widespre...

Invasive plants often emanate from southern gardens

Treesearch

J.H. Miller; A. Miller

2009-01-01

Did you know that heavenly bamboo, thorny olive, English ivy, Boston fern, privets and many garden favorites are invading forests to their and thus our detriment? Garden clubs should band together to protect our natural vegetation against invasive plants that take over the habitat of the native flora. Often called non-native, exotic, or noxious weeds, they...

Germination response of prairie dropseed and hairy goldaster to stratification and temperature

Treesearch

Aurora R. Roemmich; Jack L. Butler; Gary E. Larson; E. Brent Turnipseed

2012-01-01

The unique vegetation assemblage of the Black Hills in conjunction with the frequent occurrence of natural and anthropogenic disturbances emphasizes the need to use locally adapted native species in a wide variety of restoration efforts. However, a general lack of information regarding germination and propagation requirements for most native plant species has...

Herbicides: an unexpected ally for native plants in the war against invasive species

Treesearch

Andrea Watts; Tim Harrington; Dave Peter

2015-01-01

Herbicides are primarily used for protecting agricultural crops from weeds and controlling vegetation competition in newly planted forest stands. Yet for over 40 years, they have also proven useful in controlling invasive plant species in natural areas. Nonnative invasive plant species, if not controlled, can displace native species and disrupt an ecosystem by changing...

Saltcedar control and water salvage on the Pecos River, Texas, 1999 to 2003

Treesearch

Charles R. Hart; Larry D. White; Alyson McDonald; Zhuping Sheng

2007-01-01

A large scale ecosystem restoration program was initiated in 1997 on the Pecos River in western Texas. Saltcedar (Tamarix spp.), a non-native invasive tree, had created a near monoculture along the banks of the river by replacing most native vegetation. Local irrigation districts, private landowners, federal and state agencies, and private industry...

The role of animal seed dispersal in accelerating native forest regeneration on degraded tropical lands.

Treesearch

J.M. Wunderle Jr.

1997-01-01

this paper reviews the characteristicas of animal seed dispersal. relevant to tropical forest restoration efforts and discusses their managment implication. In many tropical regions seed dispersal by animals is the predominant form of dissemination of propagules and has a potential to facilitate recolonization of native vegetation on degraded sites.

Loblolly pine seedling response to competition from exotic vs. native plants

Treesearch

Pedram Daneshgar; Shibu Jose; Craig Ramsey; Robin Collins

2006-01-01

A field study was conducted in Santa Rosa County, FL to test the hypothesis that an exotic understory would exert a higher degree of competition on tree seedling establishment and growth than native vegetation. The study site was a 60 ha cutover area infested with the invasive exotic cogongrass [Imperata cylindrica (L.) Raeusch.]. A completely...

Hyperspectral canopy reflectance as a predictor for root concentrations of nitrogen and carbon in native and non native grass species

USDA-ARS?s Scientific Manuscript database

Land managers, scientists, and crop professionals need real-time, inexpensive, and labor-saving methods to determine below-ground biomass and potential carbon (C) and nitrogen (N) inputs of that biomass. Remote sensing is a non-destructive tool that monitors vigor of vegetation and has been used t...

Hyperspectral canopy reflectance as a predictor for root concentrations of nitrogen and carbon in native and non native grass species

USDA-ARS?s Scientific Manuscript database

Land managers, scientists, and crop professionals need real-time, inexpensive, and labor-saving methods to determine below-ground biomass and potential carbon (C) and nitrogen (N) inputs of that biomass. Remote sensing is a non-destructive tool that monitors vigor of vegetation and has been used ...

The influence of ungulates on non-native plant invasions in forests and rangelands: a review.

Treesearch

Catherine G. Parks; Michael J. Wisdom; John G. Kie

2005-01-01

Herbivory by wild and domestic ungulates can strongly influence vegetation composition and productivity in forest and range ecosystems. However, the role of ungulates as contributors to the establishment and spread of non-native invasive plants is not well known. Ungulates spread seeds through endozoochory (passing through an animal's digestive tract) or...

Groundwater, Vegetation, and Atmosphere: Comparative Riparian Evapotranspiration, Restoration, and Water Salvage

Treesearch

J. R. Cleverly; C. N. Dahm; J. R. Thibault; D. McDonnell; J. E. Allred Coonrod

2006-01-01

As water shortages persist throughout the Western U.S., a great deal of money and effort is directed toward decreasing riparian water loss, thereby enabling continued water use by irrigators, industry, and municipalities. This study focuses upon long-term measurement of evapotranspiration (ET) by native and non-native riparian species along the Middle Rio Grande (MRG)...

Hybridization of two biotypes of Lilioceris cheni will not hinder biological control of air potato, Dioscorea bulbifera

USDA-ARS?s Scientific Manuscript database

Dioscorea bulbifera L. (Dioscoreales: Dioscoreaceae), air potato, is a perennial vine native to Asia and Africa that is invasive in Florida and other parts of the southeastern United States. Air potato vines can grow more than 20 meters long and outcompete native vegetation in a variety of habitats....

A case study on dune response to infragravity waves

NASA Astrophysics Data System (ADS)

Li, Wenshan; Wang, Hui; Li, Huan; Wu, Shuangquan; Li, Cheng

2017-08-01

A series of numerical simulations were conducted using the process-based model XBeach to investigate dune response under normal and getting rid of infragravity wave conditions with different slopes. Erosion volume upside the dune toe and dune top recession are set as indicators for dune vulnerability as well as defence capacity for its front-beach. Results show that both dune erosion volume and dune top recession decrease with gentler dune slopes. Of all the simulation cases, dune with a face slope of 1/1 lost most sand and supplied most sand for lower-bed. The presence of infragravity waves is validated to be crucial to dune vulnerability. The dune erosion volume is shown to decrease by 44.5%∼61.5% and the dune top recession decreased by 0%∼45.5% correspondingly, in the case that infragravity motion is not taken into account during simulation for different dune slopes.

Vegetation map of the watersheds between Kawela and Kamalō Gulches, Island of Molokaʻi, Hawaiʻi

USGS Publications Warehouse

Jacobi, James D.; Ambagis, Stephen

2013-01-01

In this document we describe the methods and results of a project to produce a large-scale map of the dominant plant communities for an area of 5,118.5 hectares encompassing the Kawela and Kamalō watersheds on the island of Molokaʻi, Hawaiʻi, using digital image analysis of multi-spectral satellite imagery. Besides providing a base map of the area for land managers to use, this vegetation map serves as spatial background for the U.S. Geological Survey’s (USGS) Molokaʻi Ridge-to-Reef project, which is an interdisciplinary study of erosion and sediment transport within these watersheds. A total of 14 mapping units were identified for the Kawela-Kamalō project area. The most widespread units were the ʻŌhiʻa montane wet or mesic forest and No vegetation or very sparse grasses/shrubs communities, each present in more than 800 hectares, or 16 percent of the mapping area. Next largest were the Kiawe woodland with alien grass understory and ʻAʻaliʻi dry shrubland units, each of which covered more than 500 hectares, or more than 12 percent of the area; followed by the Mixed native mesic shrubland, ʻIlima and mixed grass dry shrubland, Mixed alien grass with ʻilima shrubs, and the Mixed alien forest with alien shrub/grass understory communities, which ranged in size from approximately 391 to 491 hectares, or 7.6 to 9.6 percent of the project site. The other six mapped units covered less than 170 hectares of the landscape. Six of the map units were dominated by native vegetation, covering a total of 2,535.2 hectares combined, or approximately 50 percent of the project area. The remaining map units were dominated by nonnative species and represent vegetation types that have resulted from invasion and establishment of plant species that had been either purposely or accidently introduced into Hawaiʻi since humans arrived in these islands more than 1,500 years ago. The preponderance of mapping units that are dominated by alien species of plants is a strong indication of how much anthropogenic disturbance has occurred in this area. The native-dominated ʻŌhiʻa forest and uluhe fern communities are probably most similar to the vegetation that was originally found in the upper part of the project area this area. Portions of the mixed mesic native shrub community still persist in the lowland mesic zone, but below that area, the vegetation is either dominated by alien species, or artificially opened by animal grazing and erosion, even in the few units that are still dominated by native species. The map produced for the Kawela to Kamalō watersheds can be used as a baseline for assessing the distribution and abundance of the various plant communities found across this landscape at the time of the imagery (2004). It can also be used to help understand the dynamics of the vegetation and other attributes of this watershed—such as erosion and surface transport of sediment, relative to current and future habitat conditions.

Terrestrial sensitivity to abrupt cooling recorded by aeolian activity in northwest Ohio, USA

USGS Publications Warehouse

Campbell, M.C.; Fisher, T.G.; Goble, R.J.

2011-01-01

Optically stimulated luminescence dated sand dunes and Pleistocene beach ridges in northwest Ohio are used to reconstruct landscape modification more than 5000. yr after deglaciation. Four of the OSL ages (13.3-11.1. ka) cluster around the Younger Dryas cold event, five ages (10.8-8.2. ka) cluster around the Preboreal, one young age (0.9-0.7. ka) records more recent aeolian activity, and one age of 15.1-13.1. ka dates a barrier spit in Lake Warren. In northwest Ohio, both landscape instability recorded by aeolian activity and a vegetation response recorded by pollen are coeval with the Younger Dryas. However, the climate conditions during the Preboreal resulting in aeolian activity are not recorded in the available pollen records. From this, we conclude that aeolian dunes and surfaces susceptible to deflation are sensitive to cooler, drier episodes of climate and can complement pollen data. Younger Dryas and Preboreal aged aeolian activity in northwestern Ohio coincides with aeolian records elsewhere in the Great Lakes region east of the prairie-forest ecotone. ?? 2011 University of Washington.

Analysis of ERTS-1 imagery and its application to evaluation of Wyoming's natural resources

NASA Technical Reports Server (NTRS)

Marrs, R. W.

1973-01-01

The author has identified the following significant results. A summary of the significant results of the studies completed during the July-August, 1973 period includes: (1) ERTS-1 image brightness contrasts can be related to important contrasts in rangeland and forest vegetation communities of the Laramie Basin. (2) Stereoscopic viewing is essential for correct structural interpretation in outcrop patterns in some areas. (3) Complex fracture patterns which may have exerted a controlling influence on intrusive activity in the Absaroka Mountains can be mapped from ERTS. (4) Volcanic lithologies of the Yellowstone region are often differentiated on the basis of their textures, and cannot be successfully mapped by photogeologic interpretation of ERTS-1 imagery. Ground spectral readings confirm a general lack of contrast between these lithologies in the four ERTS-1 MSS bands. (5) Major dune fields can be recognized and defined from ERTS-1 image interpretations and recognition of differences in stabilizing plant communities (some of which may be mappable from ERTS-1) yields information about migration history of the dune fields.

- and Cross-Polarization 13C NMR Evidence of Alterations in Molecular Composition of Humic Substances Following Afforestation with Eucalypt in Distinct Brazilian Biomes

NASA Astrophysics Data System (ADS)

Silva, I. R.; Soares, E. M.; Schmidt-Rohr, K.; Novais, R.; Barros, N.; Fernandes, S.

2010-12-01

The effect of planting fast growing tree species on SOM quality in tropical regions has been overlooked. In the present study 13C-NMR approaches were used to evaluate the impact of eucalypt cultivation on humic and fulvic acids molecular composition. The results indicate that the replacement of native vegetation by eucalypt plantations increased the relative contribution of aliphatic groups in HA from soils previously under Atlantic Forest, Grassland, and the Cerrado (Curvelo site only). The same trend was observed for FA, except in the Curvelo site. A trend for degradation and smaller contribution of O-alkyl C (carbohydrates) in HA was observed in soils under eucalyptus in Atlantic Forest and Cerrado. For FA such decreases were seen in Cerrado and Grassland biomes after eucalypt planting. In the area cultivated with pasture in the Atlantic Forest biome and in the Grassland soil, the largest contributions of lignin-derived compounds were detected in HA. The HA from the Cerrado at the Curvelo site, where the woody vegetation is virtually devoid of grassy species, showed the lowest intensity of lignin signal then those from the Cerrado sensu stricto in Itacambira, where grass species are more abundant. At our study sites, charred material are most likely derived from burning of the native vegetation, as naturally occurs in the Cerrado region, or anthropogenic fires in the Grassland biome. Burning of harvest residues in eucalypt fields was also a common practice in the early rotations. The replacement of native vegetation by eucalypt plantations increases the relative contribution of nonpolar alkyl groups in HA from soils previously under Atlantic Forest, Grassland, and the Cerrado (Curvelo site only) biomes. There is evidence of substantial contribution of lignin-derived C to HA and FA, especially in sites planted with Brachiaria sp pastures. Eucalypt introduction decreases the relative contribution of carbohydrates in HA and FA. 13C DP/MAS NMR functional groups in the humic and fulvic acid samples from the Eucalypt and native vegetation soils in the Atlantic Forest, Cerrado and Grassland biomes

Overcoming barriers to seedling regeneration during forest restoration on tropical pasture land and the potential value of woody weeds

PubMed Central

Elgar, Amelia T.; Freebody, Kylie; Pohlman, Catherine L.; Shoo, Luke P.; Catterall, Carla P.

2014-01-01

Combating the legacy of deforestation on tropical biodiversity requires the conversion to forest of large areas of established pasture, where barriers to native plant regeneration include competition with pasture grasses and poor propagule supply (seed availability). In addition, initial woody plants that colonise pasture are often invasive, non-native species whose ecological roles and management in the context of forest regeneration are contested. In a restoration experiment at two 0.64 ha sites we quantified the response of native woody vegetation recruitment to (1) release from competition with introduced pasture grasses, and (2) local facilitation of frugivore-assisted seed dispersal provided by scattered woody plants and artificial bird perches. Herbicide pasture grass suppression during 20 months caused a significant but modest increase in density of native woody seedlings, together with abundant co-recruitment of the prominent non-native pioneer wild tobacco (Solanum mauritianum). Recruitment of native species was further enhanced by local structure in herbicide-treated areas, being consistently greater under live trees and dead non-native shrubs (herbicide-treated) than in open areas, and intermediate under bird perches. Native seedling recruitment comprised 28 species across 0.25 ha sampled but was dominated by two rainforest pioneers (Homalanthus novoguineensis, Polyscias murrayi). These early results are consistent with the expected increase in woody vegetation recruitment in response to release from competitive and dispersive barriers to rainforest regeneration. The findings highlight the need for a pragmatic consideration of the ecological roles of woody weeds and the potential roles of “new forests” more broadly in accelerating succession of humid tropical forest across large areas of retired agricultural land. PMID:24904602

Agglomeration of a comprehensive model for the wind-driven sand transport at the Belgian Coast

NASA Astrophysics Data System (ADS)

Strypsteen, Glenn; Rauwoens, Pieter

2016-04-01

Although a lot of research has been done in the area of Aeolian transport, it is only during the last years that attention has been drawn to Aeolian transport in coastal areas. In these areas, the physical processes are more complex, due to a large number of transport limiting parameters. In this PhD-project, which is now in its early stage, a model will be developed which relates the wind-driven sand transport at the Belgian coast with physical parameters such as the wind speed, humidity and grain size of the sand, and the slope of beach and dune surface. For the first time, the interaction between beach and dune dynamics is studied at the Belgian coast. The Belgian coastline is only 67km long, but densely populated and therefore subject to coastal protection and safety. The coast mostly consists of sandy beaches and dikes. Although, still 33km of dunes exist, whose dynamics are far less understood. The overall research approach consists of three pathways: (i) field measurements, (ii) physical model tests, and (iii) numerical simulations. Firstly and most importantly, several field campaigns will provide accurate data of meteo-marine conditions, morphology, and sand transport events on a wide beach at the Belgian Coastline. The experimental set-up consists of a monitoring station, which will provide time series of vegetation cover, shoreline position, fetch distances, surficial moisture content, wind speed and direction and transport processes. The horizontal and vertical variability of the event scale Aeolian sand transport is analyzed with 8 MWAC sand traps. Two saltiphones register the intensity and variations of grain impacts over time. Two meteo-masts, each with four anemometers and one wind vane, provide quantitative measurements of the wind flow at different locations on the beach. Surficial moisture is measured with a moisture sensor. The topography measurements are typically done with laser techniques. To start, two sites are selected for measurement campaigns: one consists of the typical beach - dike system, a second site involves the dunes. First results of the measured data will be presented at the conference, together with a comparison to empirical correlations available in literature. Next to the field measurements, we propose physical model tests to provide data that is difficult to measure in the field. They will be used to determine the shear velocity and critical shear velocity in function of the transport flux. The effect of surficial moisture, vegetation and morphologic landforms will also be investigated in the model tests. Numerical simulations will provide a better insight in the physical processes of the Aeolian events and will be validated with the experimental results from the field campaigns and the physical model tests. The ultimate goal of the PhD is to obtain a sand transport model for the Belgian Coast, which can be used to assess the stability of nourishments in a quantitative matter, but it also will gain a better insight in the beach and dune interactions with the changing climate.

Past and current trends of change in a dune prairie/oak savanna reconstructed through a multiple-scale history

USGS Publications Warehouse

Cole, K.L.; Taylor, R.S.

1995-01-01

The history of a rapidly changing mosaic of prairie and oak savanna in northern Indiana was reconstructed using several methods emphasizing different time scales ranging from annual to millennial. Vegetation change was monitored for 8 yr using plots and for 30 yr using aerial photographs. A 20th century fire history was reconstructed from the stand structure of multiple-stemmed trees and fire scars. General Land Office Survey data were used to reconstruct the forest of A.D. 1834. Fossil pollen and charcoal records were used to reconstruct the last 4000 yr of vegetation and fire history. Since its deposition along the shore of Lake Michigan about 4000 yr ago, the area has followed a classical primary dune successional sequence, gradually changing from pine forest to prairie/oak savanna between A.D. 264 and 1007. This successional trend, predicted in the models of Henry Cowles, occurred even though the climate cooled and prairies elsewhere in the region retreated. Severe fires in the 19th century reduced most tree species but led to a temporary increase in Populus tremuloides. During the last few decades, the prairie has been invaded by oaks and other woody species, primarily because of fire suppression since A.D. 1972. The rapid and complex changes now occurring are a response to the compounded effects of plant succession, intense burning and logging in the 19th century, recent fire suppression, and possibly increased airborne deposition of nitrates. The compilation of several historical research techniques emphasizing different time scales allows this study of the interactions between multiple disturbance variables

Undrowning a lost world — The Marine Isotope Stage 3 landscape of Gibraltar

NASA Astrophysics Data System (ADS)

Rodríguez-Vidal, Joaquín; Finlayson, Geraldine; Finlayson, Clive; Negro, Juan J.; Cáceres, Luis M.; Fa, Darren A.; Carrión, José S.

2013-12-01

The Rock of Gibraltar, at the south-western extreme of the Iberian Peninsula and 21 km from the North African coast, is a 6-km long limestone peninsula which was inhabited by Neanderthals from MIS 5e until the end of MIS 3. A total of 8 sites, either with Neanderthal fossils or their Mousterian lithic technology, have been discovered on the Rock. Two, Gorham's and Vanguard Caves, are the subject of ongoing research. These caves are currently at sea level, but during MIS 3 faced an emerged coastal shelf with the shoreline as far as 5 km away at times. They hold a unique archive of fauna and flora, in the form of fossils, charcoal and pollen, helping environmental reconstruction of now-submerged shelf landscapes. In addition, geological and geomorphological features - a 300-metre dune complex, elevated aeolian deposits, raised beaches, scree, speleothems - complement the biotic picture. The work is further complemented by a study of the ecology of the species recorded at the site, using present-day observations. The species composition in this fossil record closely matches the present day fauna and vegetation of the Doñana National Park, SW Spain: a mosaic of pine groves, coastal dunes, shrubland and seasonal wetlands and currently the richest reserve in terms of biodiversity in the Iberian Peninsula, located only 100 km to the northwest from Gibraltar. All this information permits, for the first time, the quantification of the vegetation structure of the ancient coastal plain and the modelling of the spatio-temporal dynamics of the MIS 3 coastal shelf off Gibraltar.

Exploring inner structure of Titan's dunes from Cassini Radar observations

NASA Astrophysics Data System (ADS)

Sharma, P.; Heggy, E.; Farr, T. G.

2013-12-01

Linear dunes discovered in the equatorial regions of Titan by the Cassini-Huygens mission are morphologically very similar to many terrestrial linear dune fields. These features have been compared with terrestrial longitudinal dune fields like the ones in Namib desert in western Africa. This comparison is based on the overall parallel orientation of Titan's dunes to the predominant wind direction on Titan, their superposition on other geomorphological features and the way they wrap around topographic obstacles. Studying the internal layering of dunes has strong implications in understanding the hypothesis for their origin and evolution. In Titan's case, although the morphology of the dunes has been studied from Cassini Synthetic Aperture Radar (SAR) images, it has not been possible to investigate their internal structure in detail as of yet. Since no radar sounding data is available for studying Titan's subsurface yet, we have developed another technique to examine the inner layering of the dunes. In this study, we utilize multiple complementary radar datasets, including radar imaging data for Titan's and Earth's dunes and Ground Penetrating Radar (GPR)/radar sounding data for terrestrial dunes. Based on dielectric mixing models, we suggest that the Cassini Ku-band microwaves should be able to penetrate up to ~ 3 m through Titan's dunes, indicating that the returned radar backscatter signal would include contributions from both surface and shallow subsurface echoes. This implies that the shallow subsurface properties can be retrieved from the observed radar backscatter (σ0). In our analysis, the variation of the radar backscatter as a function of dune height is used to provide an insight into the layering in Titan's dunes. We compare the variation of radar backscatter with elevation over individual dunes on Titan and analogous terrestrial dunes in three sites (Great Sand Sea, Siwa dunes and Qattaniya dunes) in the Egyptian Sahara. We observe a strong, positive correlation between the backscatter and elevation along dune profile for the larger, older dunes in the Great Sand Sea in south-western Egypt and Siwa dune field in north-western Egypt, as opposed to the weak negative correlation exhibited by the smaller, younger Qattaniya dunes in north-eastern Egypt. This result is reinforced by our GPR survey on a large dune in the Siwa dune field and a smaller dune in the Qattaniya dune field. Our GPR data suggest the internal structure of larger dunes to consist of greater number of layers/cross-strata than smaller ones in the first 8 meters of the subsurface, which corresponds to the radar penetration depth at (0.8-1.2) GHz. Dunes on Titan exhibit backscatter-height dependency similar to the smaller Qattaniya dunes. In particular, the Shangri-La and Belet dunes on Titan exhibit a significantly stronger, negative correlation for the backscatter-height dependency compared to the Fensal and Aztlan dunes, suggesting a difference in the internal layering, relative ages and formation history of these dunes on Titan.

Late Quaternary eolian and alluvial response to paleoclimate, Canyonlands, southeastern Utah

USGS Publications Warehouse

Reheis, M.C.; Reynolds, R.L.; Goldstein, H.; Roberts, H.M.; Yount, J.C.; Axford, Y.; Cummings, L.S.; Shearin, N.

2005-01-01

In upland areas of Canyonlands National Park, Utah, thin deposits and paleosols show late Quaternary episodes of eolian sedimentation, pedogenesis, and climate change. Interpretation of the stratigraphy and optically stimulated luminescence ages of eolian and nearby alluvial deposits, their pollen, and intercalated paleosols yields the following history: (1) Eolian deposition at ca. 46 ka, followed by several episodes of alluviation from some time before ca. 40 ka until after 16 ka (calibrated). (2) Eolian deposition from ca. 17 ka to 12 ka, interrupted by periods of pedogenesis, coinciding with late Pleistocene alluviation as local climate became warmer and wetter. (3) A wetter period from 12 to 8.5 ka corresponding to the peak of summer monsoon influence, during which soils formed relatively quickly by infiltration of eolian silt and clay, and trees and grasses were more abundant. (4) A drier period between ca. 8.5 and 6 ka during which sheetwash deposits accumulated and more desertlike vegetation was dominant; some dunes were reactivated at ca. 8 ka. (5) Episodic eolian and fluvial deposition during a wetter, cooler period that began at ca. 6 ka and ended by ca. 3-2 ka, followed by a shift to drier modern conditions; localized mobilization of dune sand has persisted to the present. These interpretations are similar to those of studies at the Chaco dune field, New Mexico, and the Tusayan dune field, Arizona, and are consistent with paleoclimate interpretations of pollen and packrat middens in the region. A period of rapid deposition and infiltration of eolian dust derived from distant igneous source terranes occurred between ca. 12 and 8 ka. Before ca. 17 ka, and apparently back to at least 45 ka, paleosols contain little or no such infiltrated dust. After ca. 8 ka, either the supply of dust was reduced or the more arid climate inhibited translocation of dust into the soils. ?? 2005 Geological Society of America.

Quantifying spatial and temporal trends in beach-dune volumetric changes using spatial statistics

NASA Astrophysics Data System (ADS)

Eamer, Jordan B. R.; Walker, Ian J.

2013-06-01

Spatial statistics are generally underutilized in coastal geomorphology, despite offering great potential for identifying and quantifying spatial-temporal trends in landscape morphodynamics. In particular, local Moran's Ii provides a statistical framework for detecting clusters of significant change in an attribute (e.g., surface erosion or deposition) and quantifying how this changes over space and time. This study analyzes and interprets spatial-temporal patterns in sediment volume changes in a beach-foredune-transgressive dune complex following removal of invasive marram grass (Ammophila spp.). Results are derived by detecting significant changes in post-removal repeat DEMs derived from topographic surveys and airborne LiDAR. The study site was separated into discrete, linked geomorphic units (beach, foredune, transgressive dune complex) to facilitate sub-landscape scale analysis of volumetric change and sediment budget responses. Difference surfaces derived from a pixel-subtraction algorithm between interval DEMs and the LiDAR baseline DEM were filtered using the local Moran's Ii method and two different spatial weights (1.5 and 5 m) to detect statistically significant change. Moran's Ii results were compared with those derived from a more spatially uniform statistical method that uses a simpler student's t distribution threshold for change detection. Morphodynamic patterns and volumetric estimates were similar between the uniform geostatistical method and Moran's Ii at a spatial weight of 5 m while the smaller spatial weight (1.5 m) consistently indicated volumetric changes of less magnitude. The larger 5 m spatial weight was most representative of broader site morphodynamics and spatial patterns while the smaller spatial weight provided volumetric changes consistent with field observations. All methods showed foredune deflation immediately following removal with increased sediment volumes into the spring via deposition at the crest and on lobes in the lee, despite erosion on the stoss slope and dune toe. Generally, the foredune became wider by landward extension and the seaward slope recovered from erosion to a similar height and form to that of pre-restoration despite remaining essentially free of vegetation.

CO2 sequestration in two mediterranean dune areas subjected to a different level of anthropogenic disturbance

NASA Astrophysics Data System (ADS)

Bonito, Andrea; Ricotta, Carlo; Iberite, Mauro; Gratani, Loretta; Varone, Laura

2017-09-01

Coastal sand dunes are among the most threatened habitats, especially in the Mediterranean Basin, where the high levels of human pressure impair the presence of plant species, putting at risk the maintenance of the ecosystem services, such as CO2 sequestration provided by these habitats. The aim of this study was to analyze how disturbance-induced changes in plant species abundance patterns account for variations in annual CO2 sequestration flow (CS) of Mediterranean sand dune areas. Two sites characterized by a high (site HAD) and a lower (site LAD) anthropogenic disturbance level were selected. At both sites, plant species number, cover, height and CS based on net photosynthesis measurements were sampled. At the plant species level, our results highlighted that Ammophila arenaria and Pancratium maritimum, had a key role in CS. Moreover, the results revealed a patchy species assemblage in both sites. In particular, HAD was characterized by a higher extension of the anthropogenic aphytoic zone (64% of the total transect length) than LAD. In spite of the observed differences in plant species composition, there were not significant differences between HAD and LAD in structural and functional traits, such as plant height and net photosynthesis. As a consequence, HAD and LAD had a similar CS (443 and 421 Mg CO2 ha-1 y-1, respectively). From a monetary point of view, our estimates based on the social costs of carbon revealed that the flow of sequestered CO2 valued on an average 3181 ± 114 ha-1 year-1 (mean value for the two sites). However, considering also the value of the CO2 negative flow related to loss of vegetated area, the annual net benefit arising from CO2 sequestration amounted to 1641 and 1772 for HAD and LAD, respectively. Overall, the results highlighted the importance to maximize the efforts to preserve dune habitats by applying an effective management policy, which could allow maintaining also a regulatory ecosystem service such as CO2 sequestration.

Deforestation and benthic indicators: how much vegetation cover is needed to sustain healthy Andean streams?

PubMed

Iñiguez-Armijos, Carlos; Leiva, Adrián; Frede, Hans-Georg; Hampel, Henrietta; Breuer, Lutz

2014-01-01

Deforestation in the tropical Andes is affecting ecological conditions of streams, and determination of how much forest should be retained is a pressing task for conservation, restoration and management strategies. We calculated and analyzed eight benthic metrics (structural, compositional and water quality indices) and a physical-chemical composite index with gradients of vegetation cover to assess the effects of deforestation on macroinvertebrate communities and water quality of 23 streams in southern Ecuadorian Andes. Using a geographical information system (GIS), we quantified vegetation cover at three spatial scales: the entire catchment, the riparian buffer of 30 m width extending the entire stream length, and the local scale defined for a stream reach of 100 m in length and similar buffer width. Macroinvertebrate and water quality metrics had the strongest relationships with vegetation cover at catchment and riparian scales, while vegetation cover did not show any association with the macroinvertebrate metrics at local scale. At catchment scale, the water quality metrics indicate that ecological condition of Andean streams is good when vegetation cover is over 70%. Further, macroinvertebrate community assemblages were more diverse and related in catchments largely covered by native vegetation (>70%). Our results suggest that retaining an important quantity of native vegetation cover within the catchments and a linkage between headwater and riparian forests help to maintain and improve stream biodiversity and water quality in Andean streams affected by deforestation. This research proposes that a strong regulation focused to the management of riparian buffers can be successful when decision making is addressed to conservation/restoration of Andean catchments.

Deforestation and Benthic Indicators: How Much Vegetation Cover Is Needed to Sustain Healthy Andean Streams?

PubMed Central

Iñiguez–Armijos, Carlos; Leiva, Adrián; Frede, Hans–Georg; Hampel, Henrietta; Breuer, Lutz

2014-01-01

Deforestation in the tropical Andes is affecting ecological conditions of streams, and determination of how much forest should be retained is a pressing task for conservation, restoration and management strategies. We calculated and analyzed eight benthic metrics (structural, compositional and water quality indices) and a physical-chemical composite index with gradients of vegetation cover to assess the effects of deforestation on macroinvertebrate communities and water quality of 23 streams in southern Ecuadorian Andes. Using a geographical information system (GIS), we quantified vegetation cover at three spatial scales: the entire catchment, the riparian buffer of 30 m width extending the entire stream length, and the local scale defined for a stream reach of 100 m in length and similar buffer width. Macroinvertebrate and water quality metrics had the strongest relationships with vegetation cover at catchment and riparian scales, while vegetation cover did not show any association with the macroinvertebrate metrics at local scale. At catchment scale, the water quality metrics indicate that ecological condition of Andean streams is good when vegetation cover is over 70%. Further, macroinvertebrate community assemblages were more diverse and related in catchments largely covered by native vegetation (>70%). Our results suggest that retaining an important quantity of native vegetation cover within the catchments and a linkage between headwater and riparian forests help to maintain and improve stream biodiversity and water quality in Andean streams affected by deforestation. This research proposes that a strong regulation focused to the management of riparian buffers can be successful when decision making is addressed to conservation/restoration of Andean catchments. PMID:25147941

Negative effect of litter of invasive weed Lantana camara on structure and composition of vegetation in the lower Siwalik Hills, northern India.

PubMed

Singh, Harminder Pal; Batish, Daizy R; Dogra, Kuldip Singh; Kaur, Shalinder; Kohli, Ravinder Kumar; Negi, Anjana

2014-06-01

Lantana camara, an aromatic shrub, native to tropical America, was introduced into India for ornamental hedging, but later escaped and became a serious invasive weed. This study assessed the quantitative and qualitative status of plant community richness and diversity in areas invaded by L. camara in the Siwalik Hills (Himachal Pradesh, India), and explored allelopathy as a possible mechanism of interference. We measured species diversity, richness and evenness of the vegetation in areas invaded and uninvaded by L. camara. Allelopathic effects of L. camara rhizosphere soil and litter were assessed against two native plants-Achyranthes aspera (a herb) and Albizia lebbeck (a tree). Density, biomass and indices of diversity, richness and evenness were reduced by L. camara, indicating a significant alteration in composition and structure of native communities. Seedling growth of the test species was reduced in L. camara rhizosphere- and litter-amended soil. The inhibitory effect was ameliorated by the addition of activated charcoal, indicating the presence of organic inhibitors (quantified as phenolics) in the soil. Lantana invasion greatly reduces the density and diversity of the vegetation in the invaded area, and chemical interference of its litter plays an important role in invasion.