Feedbacks Between Complex Ecological and Social Models: Urban Landscape Structure, Nitrogen Flux, Vegetation Management, and Adoption of Design Scenarios

The Chesapeake Bay, the largest estuary in the U.S., is classified as "impaired waters" under the Clean Water Act. The bay suffers from declines in dissolved oxygen, submersed aquatic vegetation, and finfish and shellfish fisheries. Nitrogen loading from adjacent lands is a key cause of this impairment. State and federal agencies have agreed to reduce nitrogen loading into the Bay by 40 percent before 2011. Much progress has been made in mitigating nitrogen loading from point sources, particularly agriculture and sewage treatment plants, and attention is now turning to non-point sources of nitrogen in the bays watershed. On an area basis, urban and suburban lands contribute the most nutrients to the bay. The amount of nitrogen released to the bay is a product of interactions between hydrology, biology, chemistry, and social factors and therefore is an excellent integrator for understanding complexity in coupled natural-human ecosystems. The goal of this interdisciplinary research project is to investigate the links among landscape structure, nitrogen flux from urban watersheds, and the social and physical capacity to alter the landscape through vegetation management. A feedback loop linking these factors will be investigated. Urban designs that satisfy community preferences but also are aimed at reducing nitrogen loading will be investigated as a tool to close the feedback loop. The investigators will model how new architectural and landscape architectural designs alter landscape structure and therefore influence nitrogen export from urban and suburbanizing watersheds. They will work with managers to identify vegetation management options thought to minimize nitrogen loss from the land, and they will incorporate those options into new urban designs. The physical and social constraints on the ability of contrasting neighborhoods to adopt the prospective designs will be evaluated. The designs that prove to be adoptable by real communities will be included in models of altered metropolitan landscapes to predict the capacity of future landscape structure and associated management to prevent nitrogen flow to the bay. This project will have important implications. First, it will employ and test a new integrated land-cover classification appropriate to complex, urban regions. Second, it will expand biocomplexity theory to include connections of ecological, hydrological, and social systems with the practice of urban design. Third, the project will test the current management strategy of reducing non-point nitrogen loading by modifying urban land cover. In addition, communities, primary and secondary schools, college students, graduate students, and post-docs will benefit from the project through employment, summer student internships and teacher fellowships, teacher workshops, after-school and summer programs, and development of curricular materials. These activities will link the research with under-represented populations and will promote a "career ladder" to expose members of these groups to environmental science professions. Outreach to federal, state, and local government managers, non-profit organizations, and community groups will focus on vegetation management and design options. The results of the project will be useful to citizen groups, environmental resource managers, and metropolitan planners. Visualizations of the contrasting models will help communities and planners evaluate scenarios for economic development, community revitalization, and ecological restoration. This project is supported by an award resulting from the FY 2005 special competition in Biocomplexity in the Environment focusing on the Dynamics of Coupled Natural and Human Systems.