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Spatial and Temporal Variation in Plant Communities of Three Tidal Salt Marshes Along the York River, Virginia

Spatial and Temporal Variation in Plant Communities of Three Tidal Salt Marshes Along the York River, Virginia PDF Author: Rosemary E. Laird
Publisher:
ISBN:
Category : Salt marsh ecology
Languages : en
Pages : 142

Book Description


Spatial and Temporal Variation in Plant Communities of Three Tidal Salt Marshes Along the York River, Virginia

Spatial and Temporal Variation in Plant Communities of Three Tidal Salt Marshes Along the York River, Virginia PDF Author: Rosemary E. Laird
Publisher:
ISBN:
Category : Salt marsh ecology
Languages : en
Pages : 142

Book Description


Wetlands Function, Assessment, and Management

Wetlands Function, Assessment, and Management PDF Author: Society of Wetland Scientists (U.S.). Meeting
Publisher:
ISBN:
Category : Wetlands
Languages : en
Pages : 262

Book Description


Selected Water Resources Abstracts

Selected Water Resources Abstracts PDF Author:
Publisher:
ISBN:
Category : Hydrology
Languages : en
Pages : 1162

Book Description


Spatial and Temporal Dynamics of Salt Marsh Vegetation Across Scales

Spatial and Temporal Dynamics of Salt Marsh Vegetation Across Scales PDF Author: Daehyun Kim
Publisher:
ISBN:
Category :
Languages : en
Pages :

Book Description
Biogeographic patterns across a landscape are developed by the interplay of environmental processes operating at different spatial and temporal scales. This research investigated dynamics of salt marsh vegetation on the Skallingen salt marsh in Denmark responding to environmental variations at large, medium, and fine scales along both spatial and temporal spectrums. At the broad scale, this research addressed the importance of wind-induced rise of the sea surface in such biogeographic changes. A new hypothetical chain was suggested: recent trends in the North Atlantic Oscillation index toward its positive phase have led to increased storminess and wind tides on the ocean surface, resulting in increased frequency, duration, and magnitude of submergence and, hence, waterlogging of marsh soils and plants, which has retarded ecological succession. At the mid-scale, spatial patterns of vegetation and environmental factors were examined across tidal creeks. Sites closer to tidal creeks, compared to marsh interiors, were characterized by the dominance of later-successional species, higher bulk density, and lower nutrient contents and electrical conductivity. This finding implies that locations near creeks have experienced a better drainage condition than the inner marshes, which eventually facilitated the establishment of later-successional plants that are intolerant to physical stress. At the micro-scale, this research examined how the extent and mode of facilitation and competition vary for different combinations of plant species along physical gradients. Both positive and negative relationships were spatially manifested to a greater degree on the low marsh than on the mid marsh. This insight extends our current knowledge of scale-dependent interactions beyond pioneer zones to higher zones. On the low marsh, different types of bivariate point pattern (i.e., clustered, random, and regular) were observed for different combinations of species even at similar spatial scales. This finding implies that it is difficult to generalize at which scales competition and facilitation occur. To conclude, this research stresses the need for a holistic approach in future investigations of salt marsh biogeography. For example, based on results of this current research, it would be meaningful to develop a comprehensive simulation model that incorporates salt marsh ecology, geomorphology, and hydrology observed across scales.

Abiotic and Biotic Drivers of Spatial Variation in Salt Marsh Species Interactions and Community Dynamics

Abiotic and Biotic Drivers of Spatial Variation in Salt Marsh Species Interactions and Community Dynamics PDF Author: Akana Noto
Publisher:
ISBN:
Category :
Languages : en
Pages : 151

Book Description
Interactions among members of ecological communities often vary spatially in response to environmental differences. Yet interactions can also vary spatially as a result of biotic factors such as differences in species traits or variation in other species interactions. It is necessary to understand the conditions under which each of these drivers of variation has an effect in order to predict how species interactions will be affected both by changes in the environment and in biotic communities. In this thesis, I explore mechanisms that may cause species interactions to vary across space at local, regional and continental scales in salt marsh plant communities. Chapter 1 investigates the relationship between the environment (means and variability) and community diversity and stability in time-series data from the east and west coasts of North America. Chapter 2 experimentally investigates the effect of sea-level rise on species interactions within a marsh. Chapter 3 seeks to understand geographic variation in plant interactions among six sites spanning the California coast. Chapter 4 uses a common garden experiment to test whether spatial variation in species interactions are driven by differences among plant populations or the environment. Finally, Chapter 5 describes geographic patterns of variation in herbivore pressure to determine whether herbivory drives regional differences in interactions among plants. I found that changes in mean conditions, including sea level, can affect community diversity, stability and strength of species interactions. Environmental variability only affects community stability and diversity when it is relatively large, so increases in variability with climate change may cause plant community dynamics to become affected by both variability and means. Species interactions vary geographically along the west coast, but unlike on the east coast, do not show consistent trends with latitude. Rather, interaction strengths may differ due to trait variation among plant populations and differences in herbivore pressure. My thesis demonstrates that environmental conditions and local factors, including intraspecific phenotypic variation and herbivory, both determine the nature of species interactions in salt marshes, and that the west coast of North America shows geographic patterns in interactions that are distinct from those found on the east coast.

Concepts and Controversies in Tidal Marsh Ecology

Concepts and Controversies in Tidal Marsh Ecology PDF Author: M.P. Weinstein
Publisher: Springer Science & Business Media
ISBN: 0792360192
Category : Nature
Languages : en
Pages : 862

Book Description
Tidal salt marshes are viewed as critical habitats for the production of fish and shellfish. As a result, considerable legislation has been promulgated to conserve and protect these habitats, and much of it is in effect today. The relatively young science of ecological engineering has also emerged, and there are now attempts to reverse centuries-old losses by encouraging sound wetland restoration practices. Today, tens of thousands of hectares of degraded or isolated coastal wetlands are being restored worldwide. Whether restored wetlands reach functional equivalency to `natural' systems is a subject of heated debate. Equally debatable is the paradigm that depicts tidal salt marshes as the `great engine' that drives much of the secondary production in coastal waters. This view was questioned in the early 1980s by investigators who noted that total carbon export, on the order of 100 to 200 g m-2 y-1 was of much lower magnitude than originally thought. These authors also recognized that some marshes were either net importers of carbon, or showed no net exchange. Thus, the notion of `outwelling' has become but a single element in an evolving view of marsh function and the link between primary and secondary production. The `revisionist' movement was launched in 1979 when stable isotopic ratios of macrophytes and animal tissues were found to be `mismatched'. Some eighteen years later, the view of marsh function is still undergoing additional modification, and we are slowly unraveling the complexities of biogeochemical cycles, nutrient exchange, and the links between primary producers and the marsh/estuary fauna. Yet, since Teal's seminal paper nearly forty years ago, we are not much closer to understanding how marshes work. If anything, we have learned that the story is far more complicated than originally thought. Despite more than four decades of intense research, we do not yet know how salt marshes function as essential habitat, nor do we know the relative contributions to secondary production, both in situ or in the open waters of the estuary. The theme of this Symposium was to review the status of salt marsh research and revisit the existing paradigm(s) for salt marsh function. Challenge questions were designed to meet the controversy head on: Do marshes support the production of marine transient species? If so, how? Are any of these species marsh obligates? How much of the production takes place in situ versus in open waters of the estuary/coastal zone? Sessions were devoted to reviews of landmark studies, or current findings that advance our knowledge of salt marsh function. A day was also devoted to ecological engineering and wetland restoration papers addressing state-of-the-art methodology and specific case histories. Several challenge papers arguing for and against our ability to restore functional salt marshes led off each session. This volume is intended to serve as a synthesis of our current understanding of the ecological role of salt marshes, and will, it is hoped, pave the way for a new generation of research.

Energy Research Abstracts

Energy Research Abstracts PDF Author:
Publisher:
ISBN:
Category : Power resources
Languages : en
Pages : 956

Book Description
Semiannual, with semiannual and annual indexes. References to all scientific and technical literature coming from DOE, its laboratories, energy centers, and contractors. Includes all works deriving from DOE, other related government-sponsored information, and foreign nonnuclear information. Arranged under 39 categories, e.g., Biomedical sciences, basic studies; Biomedical sciences, applied studies; Health and safety; and Fusion energy. Entry gives bibliographical information and abstract. Corporate, author, subject, report number indexes.

Habitat Development Field Investigations, Windmill Point Marsh Development Site, James River, Virginia

Habitat Development Field Investigations, Windmill Point Marsh Development Site, James River, Virginia PDF Author: R. J. Diaz
Publisher:
ISBN:
Category : Benthos
Languages : en
Pages : 164

Book Description


Life in and Around the Salt Marshes

Life in and Around the Salt Marshes PDF Author: Michael J. Ursin
Publisher:
ISBN: 9780690489828
Category : Nature
Languages : en
Pages : 148

Book Description


The Role of Biotic and Abiotic Processes in the Zonation of Salt Marsh Plants in the Nueces River Delta, Texas

The Role of Biotic and Abiotic Processes in the Zonation of Salt Marsh Plants in the Nueces River Delta, Texas PDF Author: Michael Kevin Rasser
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

Book Description
Salt marshes provide critical ecosystem services, such as shoreline stabilization, biogeochemical cycling and habitat for wildlife, to much of the world's population living on the coasts. Emergent vascular plants are a critical component of these ecosystems. This study was a comprehensive effort to gain a better understanding of the ecology of salt marsh plants in the Nueces River delta on the south Texas coast. This knowledge is essential to understand the potential anthropogenic impacts on salt marshes, including sea-level rise, global warming, reduced freshwater inflow and coastal erosion. A combination of remote sensing analysis, field studies and experiments were used to allow analysis across spatial scales ranging from landscape patterns of vegetation to leaf level measurements of the dominant species. A novel method of image classification was developed using high-resolution multi-spectral imagery integrated with ancillary data to map the major plant communities at a landscape scale. This included a high marsh assemblage composed primarily of Spartina spartinae and a low marsh community dominated by Borrichia frutescens and Salicornia virginica. Geospatial analysis determined that the location of these plant communities was related to the distance from the tidal creek network and elevation. The B. frutescens and S. virginica assemblage was more abundant at lower elevations along the waters edge, making it vulnerable to loss from shoreline erosion. At a finer spatial scale, gradient analysis was utilized to examine the relationship between elevation, which creates environmental gradients in salt marshes, and species distribution. I discovered that elevation differences of less than 5 cm can influence both individual species and plant community distribution. One interesting finding was that the two dominant species, B. frutescens and S. virginica, share similar responses along an elevation gradient yet are observed growing in monotypic adjacent zones. I constructed a large reciprocal transplant experiment, using 160 plants at 4 sites throughout the marsh, to determine what causes the zonation between these two species. The results of this study found that S. virginica fared well wherever it was transplanted but was a weak competitor. B. frutescens survival was significantly lower in the S. virginica zone than in its own zone suggesting that abiotic factors are important in determining the zonation of this species. However, high spatial and temporal variability existed in environmental parameters such as salinity. This variability may have been caused by the semi-arid climate and irregular flooding typical in the Nueces Marsh. Therefore, I utilized a greenhouse experiment to directly test the importance of the two dominant physical factors in salt marshes, flooding and salinity. The results found that for B. frutescens the effects of flooding were not significant, however salinity at 30% reduced growth. Salinity did not influence growth of S. virginica. The greater ability of S. virginica to tolerate salinity stress has important implications because reduced freshwater inflow or climate change can increase porewater salinity, thus favoring the expansion of S. virginica, and altering the plant community structure.