Soil Science Commons^™

Towards Sociobiogeochemistry: Critical Perspectives On Anthropogenic Alterations To Soil Nitrogen Chemistry Via U.S. Urban And Suburban Development, Christopher D. Ryan

Dissertations, Theses, and Capstone Projects

The ecological impacts of changes to land use are relevant to concerns about climate change, eutrophication of waterbodies, and reductions in biodiversity. As a foundational component of ecosystem functioning, changes to soil biogeochemistry have significant effects on overall ecosystem health. With cities continuing to grow and develop in extent, the impacts of urbanization and suburbanization on soils are of particular concern. Despite a wide range of natural climatic and geologic conditions, several factors have driven similar patterns of land transformation and management across the United States. In particular, federal initiatives including the Home Owners Loan Corporation, the Federal Housing Administration, …

Carbon And Nitrogen Dynamics Of A Lagoon Salt Marsh In Davenport, California, Mark D. Gormley

Dissertations, Theses, and Capstone Projects

Wetlands are complex environments that play a critical role in regulating the global biogeochemical cycle of carbon (C) and nitrogen (N). Wetlands are critical contributors to global climate change and atmospheric chemistry since they store as much as 33% of the world’s soil organic carbon (SOC), release more than 20% of the atmospheric methane (CH₄), and produce nitrous oxide (N₂O), an extremely potent greenhouse gas (GHG). Despite the enormous radiative forcing potential of carbon dioxide (CO₂), CH₄ and N₂O derived from wetlands, uncertainties over the rates of C sequestration and GHG …

Effects Of Silvopasture Establishment On Aqueous And Gaseous Soil N Losses At The University Of New Hampshire Organic Dairy Research Farm, Kathryn Ann Slebodnik

Honors Theses and Capstones

The expansion of local agriculture in the New England region is putting increased pressure on farmers to expand their arable land base. While clear-cutting is a traditional method of converting forested land to agriculture, it is known for having adverse ecological impacts. To minimize these impacts, farmers can create a silvopasture which incorporates a portion of the original forest canopy into pastures or crop fields. This study evaluates the impact of land-use changes for agriculture on soil nitrogen (N) retention. In particular, this study investigates the differences in soil N turnover, gaseous loss, and aqueous loss among an established forest, …

Evidence Of Late Quaternary Fires From Charcoal And Siliceous Aggregates In Lake Sediments In The Eastern U.S.A., Joanne P. Ballard

Doctoral Dissertations

The late-glacial transition to the Holocene, 15,000–11,600 cal yr BP, is an enigmatic period of dynamic global changes and a major extinction event in North America. Fire is an agent of disturbance that transforms the environment physically and chemically, and affects plant community composition. To improve understanding of the linkages between fire, vegetation, and climate over the late glacial and Holocene in the eastern U.S., I analyzed lake-sediment cores for charcoal and indicators of wood ash, and compared results to existing pollen records. A new microscopic charcoal record from Anderson Pond, Tennessee revealed high fire activity from 23,000–15,000 cal yr …

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 …