Ecology and Evolutionary Biology Commons^™

Ecosystem Function And Phenotypic Variation In Spartina Alterniflora Salt Marshes, Sandra E. Voors

USF Tampa Graduate Theses and Dissertations

Biodiversity is important to ecosystem function at many scales, and variation functional traits within a species can potentially influence ecosystem functioning by altering nutrient cycling dynamics. High population extinction rates are resulting in a rapid loss of within-species biodiversity, so there is a need to better understand the importance of intraspecific variation to ecosystem-level processes. Tidal salt marshes are ideal ecosystems for investigating intraspecific variation in plant-nutrient relationships because they are dominated by a monoculture of the foundation species Spartina alterniflora, with distinct phenotypes that correspond to environmental gradients across the marsh. We conducted a field survey of existing …

A Bat-Guano-Derived Δ15N And Δ13C Record Of Paleoenvironmental Change: Zidită Cave, Romania, Daniel Martin Cleary

USF Tampa Graduate Theses and Dissertations

Because nitrogen isotopes are fractionated along the soil-plant-insect-bat-guano pathway, it may be possible to reconstruct environmental and climatic changes reflected in the nitrogen isotopic composition of guano. A 1.5-m core of bat guano from Zidită Cave (western Romania) provides a record of climatic and anthropogenic influence on the regional nitrogen cycle and paleoenvironmental controls on nitrogen transforming processes. Increasing and decreasing trends of nitrogen isotopic composition (δ¹⁵N values) correspond well with changes in the influence of farming practices, deforestation, and forest expansion. These influences likely had a significant effect on the openness of the nitrogen cycle, resulting in …

Variability In Hydrology And Ecosystem Properties And Their Role In Regulating Soil Organic Matter Stability In Wetlands Of West-Central Florida, Sharon Jean Feit

USF Tampa Graduate Theses and Dissertations

Soil organic matter (SOM) provides many ecosystem services that are necessary for continued ecosystem function. The accumulation of SOM in an ecosystem is a function of its persistence time which can range from days to thousands of years. Ecosystem properties including dominant vegetation type, soil texture, and soil moisture in various habitats can regulate the persistence time of SOM.

Wetlands, because of their associated ecosystem properties, promote SOM accumulation, but little has been done to determine the ecosystem properties that regulate its persistence over time. In west-central Florida, urbanization and increased water demands have suppressed water tables in isolated wetland …