Ecosystem subsidies in a landscape context

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ECOSYSTEM SUBSIDIES FROM INDIVIDUALS TO LANDSCAPES******No habitat is an island. Energy and nutrients flow between aquatic and terrestrial environments, carried by wind, water, plants, and animals. These nutrient flows can subsidize adjacent ecosystems, making it difficult to draw clear boundaries around species and communities. But they also present an opportunity to gain a deeper understanding of the scales of ecology from interactions between individuals to communities and landscape-level processes. Two decades of research have led to a theoretical framework that predicts the impacts of resource subsidies on recipient ecosystems. But they also point toward a larger scale of enquiry, to understand how ecosystem subsidies affect patterns of diversity at the landscape level. This includes refinements to the theory of island biogeography and classical species-area relationships.******Long-term objective. My long-term goal is to understand how connections between ecosystems driven by resource subsidies affect ecology from individuals to communities and landscapes. ******Short-term objectives for watershed research. (1) test how nutrients derived from salmon affect growth and reproduction of plants, (2) test how salmon-derived nutrients affect avian diversity across the Fraser River watershed of British Columbia, and (3) use a synthesis of the literature to consider impacts of salmon for ecosystem-based management.******Short-term objectives for island research. (4) integrate the theory of island biogeography with ecosystem subsidies to test effects of nutrients from seaweed on avian species-area relationships on islands, and (5) test effects of nutrients from seaweed on insect diversity across shoreline gradients on islands. ******Approach. I propose to test hypotheses about the impacts of resource subsidies in large field studies of watersheds and islands in a remote and relatively pristine region along the coast of British Columbia, and throughout the Fraser River basin. I propose a combination of experiments and comparative analyses to test the roles of nutrients from salmon and seaweed in driving trophic interactions, abundance, and species-area relationships. ******Impact. The research proposed here will advance our understanding of the scale of subsidies and their influence, from the performance of individuals to the assembly of communities across landscapes. This will include the first comprehensive tests of predictions arising from an integration of theories about resource subsidies and island biogeography, ranging from densities of individuals to diversity of communities. Furthermore, research on watersheds will help meet a key policy requirement in Canada, by incorporating ecological effects of salmon into ecosystem-based management.