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Upstream agriculture and infrastructure development can greatly alter downstream hydrology, cutting off water sources and modifying connectivity that is critical for wetland survival. For tracts within the Anahuac National Wildlife Refuge (ANWR) located on the Texas Gulf Coast, our overall objective was to identify how much freshwater was needed to offset these processes. We sought to examine the historical trajectory of wetlands change, identify how to optimally route water through former agricultural canals, and make initial gross estimates of the volumetric water requirements. To prioritize specific restoration actions given the extremely flat topography of this sheet flow landscape, we used a combination of field survey by Unmanned Aerial Vehicles (UAVs), direct observation via airboats, Global Navigation Satellite System (GNSS) technologies, and remote assessment using aerial photography, LIDAR datasets, and Geographic Information Systems (GIS). We found that the optimal solution would minimize construction work and the quantity of water needed for purchase, while maximizing the inundation across the landscape. The unique combination of spatial technologies applied in this study provides a template for future work in similar sheet flow-fed landscapes affected by hydrologic disconnection and relative sea level rise.

Coastal erosion is a natural process, whose intensity and occurrence have increased due to natural and anthropogenic factors. To protect the coasts, the use of hard infrastructure is a widespread practice that can be effective, mostly at a local scale. However, recent evidence also shows that downstream erosion can be accelerated in adjacent zones. Because of this, natural barriers such as coastal dunes and their plant cover have gained attention, but there is a general lack of information about the role that different species (and combinations of species) play in coastal protection. The aim of this study was to explore if the functional richness of plant species helps reduce wave erosion on embryo coastal dunes. In a wave flume, we set up a 1:1 scale artificial dune covered with different combinations of plant species (Ipomoeae pes-caprae, Sesuvium portulacastrum, and Sporobolus virginicus) and exposed it to simulated “storm waves”. We found that erosion was reduced in dunes covered by plants, but such protection was species-specific and the effectiveness of protection varied over time. Ipomoea was the most effective specie for protection. Differences between species and combinations of species were associated with their physical attributes such as growth form and plant architecture. Although we found that there are species that offer little or no protection from hydrodynamic forces, they may still be important for coastal protection through their ability to build embryo dunes through eolian processes. Indeed, nature-based coastal protection is likely to be an effective alternative to engineered solutions at many sites, but the protection provided is species-specific.

North American porcupines (Erethizon dorsatum) have expanded their range into central Texas and are now frequent users of caves as den sites. What remains unknown is how caves affect their home range, and their local habitat preferences. This information is important for management decisions on Joint Base San Antonio – Camp Bullis where novel and abundant porcupine scat in caves could jeopardize federally endangered cave-obligate arthropods by allowing for the invasion of less specialized terrestrial species. To better understand porcupine home range and habitat use at Camp Bullis, we trapped four porcupines at cave entrances and fitted them with GPS collars. The 95% home range averaged 71.3 ha for females and measured 420.6 ha for the male. The 50% core habitat averaged 55.4 ha for females and measured 7.4 ha for the male. Porcupines typically stayed near the den-cave trap site except when visiting more diverse mixed forest patches. At the landscape and point levels, individuals selected for forested cover and avoided open areas. At the home range level, individuals selected for bare ground and roads, which were likely used to get from the cave den site to feed at mixed forest patches. Typically solitary, individuals in this study tolerated sharing a cave. Because of the small sample size and single sampling location, this study represents a pilot study and additional research is needed to establish concrete conclusions. Should cave managers need to limit the cave use by porcupines, a cave gate, exclosure, or reduction of forested cover would make caves less desirable.

Sigren, J.M.; Figlus, J.; Highfield, W.; Feagin, R.A., and Armitage, A.R., 2018. The effects of coastal dune volume and vegetation on storm-induced property damage: Analysis from Hurricane Ike. In response to numerous recent high-profile cases of tropical storm and hurricane damage to coastal communities, there has been increasing attention on the storm protection services provided by coastal ecosystems. However, substantial knowledge gaps exist regarding the quantitative economic benefits of such services, particularly for coastal vegetated dune ecosystems. A novel geographic information system (GIS)-based technique for delineating, quantifying, and relating coastal dune volume, vegetation area, and geographic and built-environment covariates to sustained property damage was used for the upper Texas coast following Hurricane Ike in 2008. The multivariate regression analysis contained more than 1000 homes spanning both sides of the storm's path. Dune volume and vegetation were both significantly ...

Huff, T.P. and Feagin, R.A., 2017. Restoring tidal equilibrium: Removing a hydrologic barrier and lowering salinity at the Magnolia Inlet, Texas. In: Martinez, M.L.; Taramelli, A., and Silva, R. (eds.), Coastal Resilience: Exploring the Many Challenges from Different Viewpoints. Journal of Coastal Research, Special Issue No. 77, pp. 97–103. Coconut Creek (Florida), ISSN 0749-0208. A large area of salt marsh located between Magnolia Beach and Indianola, Texas had rapidly degraded over the last few decades due to a hydrologic barrier. Sediment and shell debris in the main tidal channel had greatly reduced flow between interior sections of marsh and the adjacent open bay, blocking all hydrologic exchange except for extreme tides. As a result, the impounded waters were often hypersaline, the vegetation was dying, and access to habitat was restricted for aquatic nekton. Our overall objective was to identify the cross section of debris that would need to be removed from the channel in order to restore ...

Huff, T.P. and Feagin, R.A., 2017. Hydrological barrier as a cause of salt marsh loss. In: Martinez, M.L.; Taramelli, A., and Silva, R. (eds.), Coastal Resilience: Exploring the Many Challenges from Different Viewpoints. Journal of Coastal Research, Special Issue No. 77, pp. 88–96. Coconut Creek (Florida), ISSN 0749-0208. The Magic Ridge Marsh located along Magnolia Beach, Texas has rapidly degraded over the last few decades. This marsh is of great importance to wildlife and dependent recreational pursuits such as bird watching at the Magic Ridge Sanctuary and fishing in the marshes and adjacent bay. In this study, we decided to focus on the shell debris pile as aerial imagery, along with local knowledge, indicated that this was the point of hydrologic disturbance. In order to restore this ecosystem, the alterations to the hydrology had to be understood and thus the multi-stage approach was chosen to single out the environmental factors that influence the marsh. Land cover analyses were conducted...

Knowledge of meso-mammal cave use is essential for natural resource managers, particularly in the management of endangered cave invertebrates. Scat left by meso-mammals represents significant nutrient inputs into the oligotrophic cave environment which can disrupt the invertebrate species composition and ecology. Since little is known about what constitutes typical timing or frequency of meso-mammal visitation, current management practices are largely speculative. Central Texas caves were historically associated with raccoons Procyon lotor, but with the loss of large predators and encroachment of woody vegetation, the now naturalized North American porcupine Erethizon dorsatum has become an established part of the local ecosystems whose effect on cave biology remains unknown. Our objective with this study was to quantify meso-mammal cave use according to seasons, time of day, weather conditions, as well ecological and physical cave characteristics. We monitored 30 caves by placing trail cameras at cave entrances for one year on Joint Base San Antonio-Camp Bullis military base just north of San Antonio, Texas. North American porcupines, raccoons, and Virginia opossums Didelphis virginiana were the three most commonly photographed meso-mammals (>87%). All meso-mammal groups showed significantly different cave use according to season, weather, and cave characteristics. Data suggested most meso-mammals were using caves for denning while raccoons and Virginia opossums also were feeding on resident invertebrate and rodent populations. In particular, Virginia opossum and raccoon, both potential predators of endangered species, showed greater use of caves containing endangered species. The results from our study represent an initial step in understanding meso-mammal cave use in central Texas.

Martinez, M.L.; Silva, R.; Lopez-Portillo, J.; Feagin, R.A., and Martinez, E. 2020. Coastal ecosystems as an ecological membrane. In: Malvarez, G. and Navas, F. (eds.), Global Coastal Issues of 2020. Journal of Coastal Research, Special Issue No. 95, pp. 97-101. Coconut Creek (Florida), ISSN 0749-0208.A membrane is a continuous layer that separates the interior of a cell from its surrounding cells or environment. It is selectively permeable because it regulates the transport of water, ions, and organic compounds. Its primary function is protection. Relatively analogous to a cell membrane, coastal ecosystems can be considered as an ecological membrane because they regulate the bidirectional transport of materials between the terrestrial and marine ecosystems and provide protection. The components of the ecological membrane include coral reefs, seagrass beds, beaches, coastal dunes, mangroves, marshes, and coastal lagoons. The selective permeability depends on the ecosystem. Pollutants and heavy metals, carbon, and nutrients are captured by the biota and sediments of mangroves, seagrasses, and marshes, and thus decrease the impact of pollution from the watershed to the ocean. Seagrasses, mangroves, beaches, and coastal dunes mitigate the inland effects of storms and hurricanes by reducing wave energy during storm surges. We examine how coastal ecosystems act as ecological membranes by looking at the evidence available. We focus on the flow of two features: heavy metals towards the ocean and waves towards the continent. We use field data to show how heavy metals are trapped by mangroves and coastal lagoons, which are porous ports of entry and exit. Also, wave flume experiments demonstrate how wave erosion is mitigated by vegetated coastal dunes, which act as protective barriers. Management schemes can be improved if coastal ecosystems are considered as components of a dynamic ecological membrane.

Scat of meso-mammals provides nutrients to cave-obligate species. If there are too few nutrient inputs, cave-obligate species have no resources, but too much and caves are invaded by terrestrial species. Our goal for this project was to determine what combination of variables most influence meso-mammal cave use by building a multinomial regression model using data collected from cave entrances in central Texas. Variables of importance in our model relate to cave accessibility, including the raccoons' (Procyon lotor) and Virginia opossums' (Didelphis virginiana) greater dexterity, and the added bulk from the North American porcupine's (Erethizon dorsatum) quills. Our model can be used to predict and manage meso-mammal cave use in central Texas. This will be especially useful in this region because North American porcupine have only recently expanded their range into central Texas and their prolific nutrient inputs, previously absent from the ecosystem, could endanger cave-obligate species.

Smooth cordgrass (Spartina alterniflora) was introduced to China in December 1979 to buffer against tides and to accelerate coastal wetland accretion. Since then, its propagation and natural dispersal have allowed this exotic plant to rapidly expand throughout coastal China with generally negative ecological effects. In 2003 S. alterniflora was labeled as an invasive plant in China, and it now covers ~50,000 ha. In this review, we first summarize the mechanisms of spread and spatial distribution of S. alterniflora, and how its physiological characteristics and strong adaptability to the available niche space in China's wetlands have enabled its spread and competition with native plants. Then we review the effects of S. alterniflora on ecosystem function in terms of habitat conversion and the alteration of biodiversity, soil carbon flux and sequestration, and various processes of nutrient regulation. We conclude that we need a long-term and context-dependent perspective, in order to maximize the benefits and minimize the costs of S. alterniflora within each of China's unique provinces.

Developing a site history and ecological site description is one of the critical steps in restoration planning for arid landscapes. This study focuses on Umm Nigga, Northeast of Kuwait, which was damaged by various human activities. The northern portion of Umm Nigga falls within the boundaries of the demilitarized zone (DMZ) adjacent to Iraq, and was fenced off to restrict public access since 1994. The central objective of this project was to use remote sensing, field assessment, and Geographical Information System (GIS) spatial data to develop a site history for restoration planning of Umm Nigga. Field observation and GIS analysis indicated that the landscape could be divided into three units along a gradient ranging from the coast to inland locations, based on geology, soil properties, and dominant vegetation. Reference sites in the DMZ were also matched for each unit. Remote sensing was used to compare vegetation cover between damaged and reference sites at selected units. Results showed that vegetation cover increased in the unfenced damaged site after the 1991 Gulf War from 2% in 1988 to 37% in 1998, but then it decreased to 23% in 2013. In the DMZ reference site, the vegetation cover also increased from 0% in 1988 to 40% in 1998, but it continued increasing through 2013 to 64%. We conclude that overgrazing and destructive camping are the major source of disturbance in the damaged areas.

Coastlines have traditionally been engineered to maintain structural stability and to protect property from storm-related damage, but their ability to endure will be challenged over the next century. The use of vegetation to reduce erosion on ocean-facing mainland and barrier island shorelines – including the sand dunes and beaches on these islands – could be part of a more flexible strategy. Although there is growing enthusiasm for using vegetation for this purpose, empirical data supporting this approach are lacking. Here, we identify the potential roles of vegetation in coastal protection, including the capture of sediment, ecological succession, and the building of islands, dunes, and beaches; the development of wave-resistant soils by increasing effective grain size and sedimentary cohesion; the ability of aboveground architecture to attenuate waves and impede through-flow; the capability of roots to bind sediments subjected to wave action; and the alteration of coastline resiliency by plant structur...

Northern bobwhites (Colinus virginianus) represent a valuable resource for upland game-bird hunters and the rural economies they support; however, bobwhite populations are declining across the United States. As ground-nesting birds, bobwhites are highly susceptible to mammalian predation during the breeding season. We placed global positioning collars on 6 coyotes (Canis latrans), 4 bobcats (Lynx rufus), and 11 raccoons (Procyon lotor) in Texas, USA, during the nesting season of bobwhites (April–August of 2009–2011) to assess their habitat selection and use, as well as determine the relative frequency with which they may encounter bobwhite nests. Overall, nightly encounter rate of predators with known bobwhite nest sites was low. Coyotes encountered nest sites 3 times more frequently than male raccoons and 7 times more frequently than bobcats. Female raccoons did not come within 50 m of any nest locations. The higher encounter rate of coyotes with bobwhite nest sites was associated with the similarity of habitat preference of coyotes and bobwhites for grasslands and grass–shrub habitats and the wide-ranging nocturnal paths of coyotes. Bobcats and raccoons had shorter nightly paths and mainly used habitats providing a greater degree of cover than is typically suitable for nesting bobwhites. Male raccoons were more mobile than females and made greater use of the grass–shrub habitat, and thus were more likely to encounter quail nests. Despite having lower individual encounter rates with bobwhite nest sites than did coyotes, male raccoons remain important predators of quail nests because they have the behavioral ability to attain greater population densities than those of the more territorial coyotes and bobcats. © 2014 The Wildlife Society.

Cline, M.D.; Feagin, R.A., and Yeager, K.M., 2014. Modeling salt marsh cover response to relative water level: Local fault motion versus global eustatic rise. The movement of growth faults on subsiding coastlines contributes to wetland losses, yet it has been unclear whether they can provide a point of reference for understanding the impacts of climate-induced relative sea level rise (RSLR) on wetland habitat. The objective of this study was to simulate land cover conversion as a function of RSLR within a wetland and to compare and contrast fault-induced elevation change with Intergovernmental Panel on Climate Change (IPCC) 2007 sea level rise projections. For an area surrounding a growth fault in Matagorda, Texas, aerial images were draped over a digital elevation model (DEM) to identify the dependent elevations of land cover classes and, subsequently, to model potential future outcomes based on variable RSLR rates. Modeling results show that rapid water-level rise can force wetland land-cover c...

Feagin, R.A.; Williams, A.M.; Popescu, S.; Stukey, J., and Washington-Allen, R.A., 2014. The use of terrestrial laser scanning (TLS) in dune ecosystems: the lessons learned. Journal of Coastal Research, 30(1), 111–119. Coconut Creek (Florida), ISSN 0749-0208. This paper presents a methodology for using terrestrial laser scanning (TLS) to quantify sand dune geomorphology. As an example of the use of TLS, we present methods that were used to investigate changes in sediment and vegetation volumes after Hurricane Ike. We collected TLS data within a 100 m 3 100 m plot on the East Matagorda Peninsula, Texas, from early September 2008 (before landfall) to early October 2009 (a year after landfall). Terrestrial laser scanning-collected laser point clouds were then interpolated into several grid sizes. From several interpolated grid sizes, 0.50 m 3 0.50 m grids were determined best for analysis as they were able to compromise two competing resolutionrelated issues: gaps caused by vegetation shadows and the natural contours of the dune. We outline several additional lessons to aid coastal researchers in strengthening their own future work: the use of reference survey stakes in an unstable environment, the development of a novel method to test for errors in point cloud registration among multiple dates, how best to interpret sediment and vegetation change analysis as derived from interpolated grids, and suggestions for incorporating mass-based sedimentary and biomass-based vegetation field studies within the volumetric context of TLS analysis.

Increases in human development of the coastal zone, sea level rise and intensity of coastal storms will test the resilience of coastal systems. An integrated approach is needed to describe geomorphic–biologic dependencies, feedbacks between processes and responses, and determine how coastal systems can be maintained or restored. The 2013 Binghamton geomorphology symposium focused on three themes in these research areas (1) the geomorphic response of coastal landforms to changes in sea level and episodic storms; (2) the way these stressors alter geomorphic–biotic interactions and reduce the resilience of coastal environments; and (3) the way natural and human processes are being integrated to restore or maintain dynamic geomorphic and biologic linkages. This issue contains eighteen papers presented at the symposium; six papers are devoted to each of these themes. The papers point to the importance of ecological systems in modulating the responses to natural physical processes and, in turn, responding to geomorphic change and the role of humans in assisting natural processes.

The establishment of large Cattle Egret (Bubulcus ibis) breeding colonies in upland residential areas of east central Texas has been observed since the early 1960s. To help understand why Cattle Egrets choose residential breeding sites and predict where these might occur in the future, the geographic extent and scale-dependent nature of the phenomenon was investigated. In east Texas and along the Texas Gulf Coast, Cattle Egret colonies were found in flooded forests or on islands. However, in east central Texas, colonies were often located in upland areas. A habitat suitability model was constructed at multiple scales, outlining land use classes thought to influence upland colony site selection: water, forest and development/residential. The model classified 79% of upland colony locations in high or very highly suitable habitat and 7% in low or very low suitable habitat. The distribution of classes was significantly different than expected considering the distribution of land cover suitability cl...

The Deepwater Horizon oil spill threatened many coastal ecosystems in the Gulf of Mexico during the spring and summer of 2010. Mitigation strategies included the construction of barrier sand berms, the restriction or blocking of inlets, and the diversion of freshwater from rivers to the coastal marshes and into the ocean, in order to flush away the oil, on the premise that these measures could reduce the quantity of oil reaching sensitive coastal environments such as wetlands or estuaries. These projects result in changes to the ecosystems that they were intended to protect. Long-term effects include alterations of the hydrological and ecological characteristics of estuaries, changes in sediment transport along the coastal barrier islands, the loss of sand resources, and adverse impacts to benthic and pelagic organisms. Although there are no easy solutions for minimizing the impacts of the Deepwater Horizon disaster on coastal ecosystems, we recommend that federal, state, and local agencies return to the ...

This study first sought to isolate a select group of landscape metrics particularly well-suited for describing dryland Mediterranean landscapes in Jordan. We examined the response of 50 landscape metrics to a large range of imagery grain sizes. Most of the metrics exhibited an expected behavior, similar to what has been previously reported in literature such as (a) a predictable (linear or power law) response to changing grain size, and (b) an unpredictable (staircase-like or erratic) response to changing grain size. Some metrics, however, exhibited a domain of scale effect, in particular the core area metrics. Using correlation analysis, the original 50 metrics were placed into 19 groups such that all metrics within a group were strongly correlated with each other, and were represented by a single representative metric. Using these representative metrics in the context of principal components analysis, we then found that six factors explained 95.35% of the total variation found in the landscape pattern. The highest loadings for these six factors, in order, were the number of patches (NP), mean proximity index (PROX_MN), largest patch index (LPI), patch cohesion index (COHESION), total core area (TCA), and the proximity index coefficient of variation (PROX_CV). It was concluded that east Mediterranean landscapes with a long history of anthropogenic-driven change showed a domain of scale for core area metrics. We also recommend that the majority of the pattern in dry Mediterranean landscapes, particularly those in Jordan, can be described with six metrics. We suggest that our procedure for landscape metric selection can be utilized in other regions of study as well.

Barrier islands provide a host of critical ecosystem services to heavily populated coastal regions of the world, yet they are quite vulnerable to ongoing sea level rise and a potential increase in the frequency and intensity of oceanic storms. These islands are being degraded at an alarming rate, in part because of anthropogenic attempts at stabilization. In this article, we outline a possible sustainability strategy that incorporates the natural degree of substrate instability on these sedimentary landscapes. We recommend placing the focus for managing barrier islands on maintaining ecosystem function and process development rather than emphasizing barrier islands as structural impediments to wave and storm energy.

Many beach management practices focus on creating an attractive environment for tourists, but can detrimentally affect long-term dune integrity. One such practice is mechanical beach raking in which the wrack line is removed from the beach front. In Texas, Sargassum fluitans and natans, types of brown alga, are the main components of wrack and may provide a subsidy to the ecosystem. In this study, we used greenhouse studies to test the hypothesis that the addition of sargassum can increase soil nutrients and produce increased growth in dune plants. We also conducted an analysis of the nutrients in the sargassum to determine the mechanisms responsible for any growth enhancement. Panicum amarum showed significant enhancement of growth with the addition of sargassum, and while Helianthus debilis, Ipomoea stolonifera, Sporobolus virginicus, and Uniola paniculata responded slightly differently to the specific treatments, none were impaired by the addition of sargassum. In general, plants seemed to respond well to unwashed sargassum and multiple additions of sargassum, indicating that plants may have adapted to capitalize on the subsidy in its natural state directly from the ocean. For coastal managers, the use of sargassum as a fertilizer could be a positive, natural, and efficient method of dealing with the accumulation of wrack on the beach.

Extended drought on the Edwards Plateau, TX, causes high mortality in grass species' populations and their replacement by recruitment from the seeds of survivors. Harvester ant nests may act as refugia for perennial plants during drought, as evidenced by a high survivorship of plants directly adjacent to nests. Because grasses tend to disperse seeds short distances and drought eliminated seed banks, we hypothesized that the spatial pattern of grass seedlings and adults would be clumped at small scales around these refugia. In contrast, nests would be regular at small to moderate scales. We studied the spatial patterns of seedlings, adults, and ant nest locations using a modified Ripley's K-function technique for transect data. Point data were collected along a 1-km transect. Spatially regular patterns were found for nests from 1.0- to 22.0-m scales. We found that two species' seedlings and adults were significantly clumped with ant nests, and two species had significantly regular spatial patterns with nests. Surprisingly, patterns of clumped seedlings occurred up to 30-m scales with nests. Nests appear to affect seedling establishment at multiple scales. These results suggest that nests may facilitate colonization for some grass populations, but regular spatial patterns in other species imply that forager seed harvest may inhibit establishment.

This study challenges the paradigm that salt marsh plants prevent lateral wave-induced erosion along wetland edges by binding soil with live roots and clarifies the role of vegetation in protecting the coast. In both laboratory flume studies and controlled field experiments, we show that common salt marsh plants do not significantly mitigate the total amount of erosion along a wetland edge. We found that the soil type is the primary variable that influences the lateral erosion rate and although plants do not directly reduce wetland edge erosion, they may do so indirectly via modification of soil parameters. We conclude that coastal vegetation is best-suited to modify and control sedimentary dynamics in response to gradual phenomena like sea-level rise or tidal forces, but is less well-suited to resist punctuated disturbances at the seaward margin of salt marshes, specifically breaking waves.

Hurricane Katrina scoured the seaward side of Dauphin Island, Alabama, and then deposited the sediment on the back side of the island into a repeating pattern of arc-shaped overwash fans. We set out to determine if sediment sorting operated at the scale of the individual overwash fan during the storm. Variograms and kriging were used to create maps of the topography and sediment patterning in terms of the mean grain size, standard deviation, skewness, and mineral composition. Mantel tests were used to correlate hypothesized directional processes with the patterns. We found that sands near the surface were spatially sorted in a direction consistent with the north-northwesterly forces of Katrina. The spatial distribution was not correlated with the topography. Our results support the concept that horizontal spatial pattern formation primarily begins as the extreme forces of a hurricane subside.

Various methods have been devised to classify plants into functional groups, yet little work has investigated how these groups differentially impact succession with spatially explicit mechanisms. In a sand dune plant community on Galveston Island, Texas, we categorized plants by their functional traits, mapped the topographical contours of the sand dunes as a first-order effect to describe the spatial distribution of environmental stress, and quantified the second-order within- and between-group associations of the plants within specific bands of these contours using Ripley's K analysis. We then quantified the influence of spatially explicit functional traits on the direction of succession over time. We found evidence that the spatial pattern of the plants at one time exerted an influence on the pattern of the plants at a later time, based on their functional traits, thereby influencing the direction of sand dune succession. This study describes the spatiotemporal mechanics that lie behind sand dune plant succession: a process that has been a classical example of facilitation for ecologists, a plant community that is at risk from global sea-level rise and hurricanes, and an important rangeland resource that is being restored around the world for its ecological, range production, and coastal protection value.

Although much research has focused upon the negative impacts of invasive Spartina alterniflora upon salt marshes dominated by other Spartina spp., little is known about its impacts upon native Scirpus mariqueter marshes. In 1997, S. alterniflora was introduced to the Jiuduansha Shoals, Yangtze Estuary, China, to accelerate the formation of marsh habitat via accretionary processes, with the larger goal of drawing waterfowl away from wetlands near the Pudong International Airport, Shanghai, China. In 2000, a nature reserve was established on the Jiuduansha Shoals, making the impact upon the native S. mariqueter community a high priority for research. Our objective was to quantify the impacts of introduced S. alterniflora and Phragmites australis to the native S. mariqueter -dominated community at this site in four elevation zones, as compared with a nearby natural shoal. We found that species diversity was greater in the lower elevations with the engineering, through elimination of the natural dominance of S. mariqueter . We also found that diversity was lessened in the higher elevations, due to rapid growth and exclusion by the planted S. alterniflora in conjunction with the native P. australis . Moreover, we found that the growth of the native S. mariqueter was stimulated when S. alterniflora was planted nearby. It is quite likely that the net effect of these ecological processes will be to accelerate further accretion, leading to an eventual replacement of the S. mariqueter -dominated community in the long-term. Future management approaches should focus upon harvesting, grazing, and perimeter-ditching the S. alterniflora to avoid this situation.

Terraced salt marsh restoration projects have been designed to maximize edge because the edges between habitat types have been shown to be the most productive locations in Spartina alterniflora salt marshes for nekton and benthic infauna. We compared terraced plots with reference plots to see how much edge was created. We also quantified the differences in the spatial patterns of the habitat in the plots. We found that reference marshes had significantly more habitat diversity and more total low marsh area. We also found that reference marshes had a greater absolute amount of low marsh edge. Yet, we found little difference between terraced restoration marshes and nearby reference marshes in Galveston Bay, Texas, USA in terms of the percent of all habitat-to-habitat edge-type combinations that were aquatic edge (water- or seagrass-to-low marsh interface), and much of the reference marshes’ area was in core marsh areas that were not suitable for high fisheries production value. Terracing appears an efficient strategy for the sole purpose of creating aquatic edge for fisheries production but does not appear to match other aspects of reference marshes in terms of their habitat composition or spatial configuration. This study shows the potential for using spatial pattern analysis to monitor restoration projects in the future.

Much of America's coastline is threatened by overdevelopment and coastal erosion, driven by global sea-level rise, a problem that is attracting the attention of researchers around the world. Although we have now acknowledged the impending risks, little is known about the response of spatially dependent dune plant communities to the loss or restriction of their habitat. In order to study this development, a spatially explicit model of sand dune plant succession on Galveston Island, Texas, was created, using sea-level rise as the primary mechanism causing local erosion. Simulations of sea-level rise scenarios developed by the Intergovernmental Panel on Climate Change demonstrated that beach erosion constrained plants to a narrow area, resulting in a breakdown of the successional process. The loss of late-succession plants along coastlines, their dependent faunal species, and possible solutions are discussed. This model and example serves as a harbinger of the future for many of the US's sandy beaches and co...

A cellular automata model of a sand dune plant community on Galveston Island, Texas, USA was utilized to test hypotheses regarding individual plant interactions and their impact upon community organization. Simulations demonstrated that both an environmental gradient and facilitative succession resulted in the formation of characteristic sand dune patterns. The results showed that the plant patterns were due to individual plant responses to their environment within their local neighborhood, yet these responses were constrained by the global history of the community. The local neighborhood was related to the “zone of influence” concept, “field of neighborhood” models, and “ecological field” theory. It is proposed that plants responded individualistically to environmental conditions within the local neighborhood and that plants were constrained by the community-unit beyond the local neighborhood. The ratio of the scale of environmental variability versus the scale of a plant's local neighborhood determined the relative importance of the individual and the community in forming pattern. This work makes important contributions to the Gleasonian–Clementsian debate, sand dune successional theory, and in pattern-based, deductive hypothesis testing with cellular automata models.

Spatial statistics were used in conjunction with standard plot experimentation to form an approach geared towards testing hypotheses about plant spatial interactions under different treatment conditions. Specifically, correlograms were used to quantify the changing patterns in the spatial distribution of plant size (total vegetative length) among pre-planted individuals within a sand box. A repeated-measures ANOVA procedure was then utilized to test for significant differences between the treatment effects as they evolved over time, where the experimental unit was the correlogram value obtained from within each sand box at a specific lag distance. Separate ANOVA tests were also executed for each spatial lag distance and temporal sampling period. In an example demonstrating both procedures, it was shown that a water-stress treatment provoked positive spatial autocorrelation to emerge up to 24 cm from Panicum amarum plants, while a normal water treatment resulted in no change in spatial structure. ...

Human-induced global climate change presents a unique and difficult challenge to the conservation of biodiversity. Despite increasing attention on global climate change, few studies have assessed the projected impacts of sea-level rise to threatened and endangered species. Therefore, we estimated the impacts of rising sea levels on the endangered Lower Keys marsh rabbit (Sylvilagus palustris hefneri) across its geographic distribution under scenarios of current conditions, low (0.3-m), medium (0.6-m), and high (0.9-m) sea-level rise. We also investigated the impacts of allowing vegetation to migrate upslope and not allowing migration and of two land-use planning decisions (protection and abandonment of human-dominated areas). Not surprisingly, under all simulations we found a general trend of decreasing total potential LKMR habitat with increasing sea-level rise. Not allowing migration and protecting human-dominated areas both tended to decrease potential LKMR habitat compared with allowing migration and abandoning human-dominated areas. In conclusion, conservation strategies at multiple scales need to be implemented in order to reduce the impact of global climate change on biodiversity and endangered species. At the regional level, managers must consider land-use planning needs that take into account the needs of both humans and biodiversity. Finally, at the local scale those agencies that are in charge of endangered species conservation and ecosystem management need to rethink static approaches to conservation or else stand by and watch ecosystems degrade and species go extinct. This can be accomplished by bioclimatic reserve systems where climatically underrepresented areas are included in conservation planning along with the standard concerns of threat, opportunity, connectivity, and viability.

We are concerned about the assertion in the Report by E. B. Barbier et al. that vegetation reduces coastal damage during extreme events (“Coastal ecosystem-based management with nonlinear ecological functions and values,” 18 January, p. [321][1]). Although the intended point was that ecosystem

Coastal wetland plants are expected to respond to global sea level rise by migrating toward higher elevations. Housing, infrastructure, and other anthropogenic modifications are expected to limit the space available for this potential migration. Here, we explore the ecological and economic effects of projected Intergovernmental Panel on Climate Change (IPCC) 2007 report sea level changes at the plant community scale using the highest horizontal (1 m) and vertical (0.01 m) resolution data available, using a 6 x 6 km area as an example. Our findings show that salt marshes do not always lose land with increasing rates of sea level rise. We found that the lower bound of the IPCC 2007 potential rise (0.18 m by 2095) actually increased the total marsh area. This low rise scenario resulted in a net gain in ecosystem service values on public property, whereas market-based economic losses were predicted for private property. The upper rise scenario (0.59 m by 2095) resulted in both public and private economic losses for this same area. Our work highlights the trade-offs between public and privately held value under the various IPCC 2007 climate change scenarios. We conclude that as wetlands migrate inland into urbanized regions, their survival is likely to be dependent on the rate of return on property and housing investments.