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Broadly, I am interested in how organisms and communities affect ecosystem processes. For my dissertation, I am examining the effects of plant communities on denitrification in wetland ecosystems. Denitrification is the microbial reduction of nitrate to dinitrogen gas. As important sites of denitrificaiton, wetlands are responsible for removing a significant fraction of mineralized nitrogen from watersheds. We know that plant communities are shifting rapidly, due to climate change, sea-level rise, land-use changes, and species invasions. We also know that plants modify denitrification rates by altering sediment conditions. However, to date, we have no framework for predicting how changes in plant-community distributions will affect denitrification. My research focuses on identifying and modeling functional plant characteristics as predictors of denitrification rates.
My field sites are located in brackish tidal marshes of Long Island, dominated primarily by Spartina alterniflora and Spartina patens, and in freshwater tidal marshes of the upper Hudson River, dominated primarily by Typha angustifolia and common invasive species Phragmites australis. Phragmites australis is also present in the upper zones of brackish marshes on Long Island. One of my ongoing projects examines the effects of small-scale removals of Phragmites with glyphosate herbicide, a common method used to control invasives, on denitrification potential of the sediment microbial community. Ongoing research in both the Hudson and on Long Island seeks to explain patterns of denitrification using functional plant characteristics. Comparisons between these two systems will allow me to investigate the generality of plant-denitrification models within different sediment contexts (i.e. fresh v. saltwater).
I employ a combination of laboratory and field approaches to study relationships among functional plant characteristics, sediment chemistry, and denitrification. My research will use plant-mesocosm experiments to investigate relationships between plant functional characteristics and sediment conditions, and resulting denitrification rates. This project will use combinations of methods that have not been used before, such as planar optode photography to measure sediment oxygenation around plant roots, and membrane inlet mass spectroscopy to measure production of N2 as the change in N2:Ar over time. My work benefits greatly from the help of my collaborators at the School of Marine and Atmospheric Sciences at Stony Brook, Brookhaven National Laboratory, the Cary Institute of Ecosystem Studies, and the assistance of Stony Brook University undergraduates (Diana Lenis, pictured left).