Three small (< 1 ha) mountain wetlands located in eastern Kentucky, host populations of two rare orchids, the white fringeless orchid, Platanthera integrilabia, and the crested yellow orchid, Platanthera cristata. Recently, concern has arisen about the persistence of the orchids. To better understand these wetlands and determine if hydrology is affecting the orchid populations, a hydrologic characterization study was initiated in 2009. Each wetland was equipped with a well nest consisting of piezometers, tensiometers, and a shallow well with a data logging pressure transducer. Chemistry and stable isotopes analysis (deuterium and 18O) of groundwater and precipitation were analyzed, and soil, topographic and channel cross-section surveys were conducted. Hydrology data suggest the primary source of water is precipitation and the primary output is evapotranspiration. Between 10 and 30 cm below the soil surface soil and tensiometer data revealed the presence of a weak fragipan, which likely contributes to seasonal ponding at the site. Management recommendations include thinning and construction of debris dams to increase the hydroperiod, surface area, and total potential volume of the wetlands.

No description available.

Many populations of migrating waterbirds in Africa and Western Eurasia are in a long-term decline, largely because of the loss of wetlands along their migration routes. Between 1950 and 1985, 63 % of the wetlands in Greece were lost due to human activities. However, humans are also a source of more direct disturbance to birds that may have a negative influence on their fitness. The purpose of this study has been to assess how human disturbance in the form of agriculture, tourism and hunting might affect the birdlife in a coastal lagoon in southwestern Greece, and, if needed, propose measures on how to improve the status of the birdlife. To evaluate this, interviews and studies of monitoring reports and literature have been conducted. The studied area, Gialova lagoon, is the southernmost wetland in the Balkan Peninsula, which makes it especially important for migratory birds. The study shows that the major threats to the lagoon have already been dealt with. However, there are still improvements that can be made. Currently, agriculture seems to have the most negative effect on the concerned area, but since there appears to be an ambition to increase tourism in the area this may change in the future. Disturbance from hunting only plays a minor role in the area around the lagoon. The establishment of an official management body as well as an official management plan would probably be an effective way to continue the conservation work and reduce the disturbance of human activities in Gialova lagoon.

Over the last century, much of the United State prairie pothole region has been converted to cultivated cropland. Concerns have been raised on government subsidized crop insurance effect on grassland to cropland conversion in the United States. Most grassland in the United State prairie pothole region are privately owned making a vivid understanding of landowners’ response to crop insurance subsidies important to facilitate effective design of prairie pothole conservation programs. The purpose of this study was to determine the extent of land use conversion with the removal of crop insurance subsidies in the United States prairie pothole region. Government subsidies on crop insurance was determined to have a measurable impact on Conservation Reserve Program land acreage within the United States. It was estimated that a 15% reduction in the net returns to cropland resulted in about 274,000 increase in the land acreage of the Conservation Reserve Program. In Conclusion, the removal of crop insurance subsidies was predicted to slow down but not stop the conversion of grassland to cropland in the United States prairie pothole region.

Identifying the ecological mechanisms that determine food web structure is critical for understanding the causes and consequences of diversity. The objective of this thesis was to identify the mechanisms structuring aquatic food webs across environmental gradients from a multi-level perspective (individual to ecosystem) using integrative methodology and field experiments to test classic ecological theory. My results demonstrate support for the dynamic constraints hypothesis, which predicts habitats with greater disturbance should have shorter food chains, but are not consistent with the ecosystem size hypothesis that predicts larger ecosystems have longer food chains. Insect and amphibian richness increased with increasing pond size and hydroperiod, indicating that insertion of new consumers into pond communities was driving variation in food-chain length. A multivariate analysis testing the influence of physicochemical variables on food-web characteristics revealed that hydroperiod and pond area had a strong influence on amphibian and invertebrate assemblages, trophic diversity and 15N range. Food-chain length did not respond strongly to any one variable, but instead responded weakly to multiple environmental variables, suggesting interacting influences on food-web structure. Conversely, the trophic niche of amphibian larvae was not influenced by pond hydroperiod, but did exhibit ontogenetic diet shifts. Populations of amphibian larvae with broader niche widths also had increased individual variation, supporting the niche variation hypothesis. In addition, I assessed whether species diversity influenced the magnitude of cross-habitat resource flow between aquatic and terrestrial habitats via emerging aquatic insects, metamorphosing amphibians, and litter deposition. Deposition into ponds far exceeded carbon exported via insect and amphibian emergences. We found a negative relationship between resource flux and the diversity of amphibians and insects, which contradicts the general pattern of positive biodiversity-ecosystem function relationships. My research strongly suggests environmental variation is a key process in shaping food-web structure and function and that multiple methodologies are needed to understand temporal and spatial dynamics of aquatic ecosystems.

Thousands of hectares of wetlands are being destroyed by oil sands mining in Alberta, and the industry must undertake wetland reclamation to compensate for these losses. Wetland vegetation has developed at some previously mined sites, however reclamation is thus far exploratory, and limited in extent. To inform reclamation practices and assist compliance monitoring I examined vegetation communities in 25 natural boreal wetlands and 20 oil sands reclaimed wetlands, developed a Vegetation-based Index of Biological Integrity (vIBI) to quantify the ecological health of wetlands, and identified possible physical and chemical barriers to reclamation. The vIBI identified 6 reclaimed wetlands in fair to good health, however reclaimed wetlands have different vegetation communities, do not produce the same level of aboveground biomass, and have lower levels of sediment nutrients than natural wetlands. To reclaim healthy wetlands, planning should focus on establishing appropriate species, and alleviate nutrient and sediment deficiencies. / Ecology

Thesis (M.S.)--University of Hawaii at Manoa, 2006. / Includes bibliographical references (leaves 143-153). / xvi, 175 leaves, bound 29 cm

Thesis (M.S.)--Ohio University, November, 2001. / Title from PDF t.p.

Thesis (M.S.)--Humboldt State University, 2007. / Includes bibliographical references (leaves 30-34). Also available via Humboldt Digital Scholar.

Thesis (Ph.D.)--Murdoch University, 2001. / Thesis submitted to the Division of Science and Engineering. Bibliography: leaves 205-222.