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FROM NUTRIENTS TO METABOLISM: LINKING NUMERIC NUTRIENT CRITERIA TO ECOSYSTEM COMPOSITION AND FUNCTION USING ECOLOGICAL STOICHIOMETRY
Impact/Purpose:
The U.S. Environmental Protection Agency recently proposed numeric nutrient criteria for spring ecosystems; however, prior research indicates nutrient concentrations alone may not adequately predict vegetation shifts for spring ecosystems. As such, this study seeks to answer how variation in the bottom-up forcing of changing resource C:N:P ratios and flow interact with top-down effects of grazing to regulate the competitive ability of vascular and algal species in springs. In addition, the study will evaluate how differing compositions of algal and vascular species affect ecosystem metabolism, a measure of ecosystem function, by deploying a suite of three real-time nutrient sensors across a gradient of species composition.
Description:
Results of these experiments will inform resource managers of the impacts of raising ecosystem C:N ratios on species composition under various flow regimes as well as the extent to which the N:P interacts with the C:N ratio to affect individual species’ competitive ability, and hence, primary producer species composition. This research also is expected to document the extent to which the bottom-up forces of flow and nutrient ratios are influenced by top-down pressure of grazing. Finally, this project will evaluate the effects of differing species composition on ecosystem metabolism.
Potential to Further Environmental/Human Health Protection
Projected population increases and associated land use change are predicted to only exacerbate existing nutrient inputs to these ecosystems. This research provides crucial information to improve environmental decision making by enabling managers to better predict potential effects of nutrient-driven eutrophication on ecosystem composition and function through the use of nutrient ratios under varying flow regimes and grazing intensities. This information can be utilized to formulate effective long-term plans to sustain and restore these economically and ecologically important spring ecosystems.