Feedbacks Between Species Composition and Ecosystem Nutrient Cycling in a California Grassland

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DEB-9910008Carla D'Antonio- University of California at BerkelyFeedbacks between species composition and ecosystem nutrient cycling in a California grassland This research investigates the effect of species composition on the cycling of nitrogen in soil of a California coastal prairie ecosystem. While most low-elevation California grasslands were formerly dominated by perennial bunchgrasses native to California, invasion by Eurasian annual grasses and forbs and, more recently, Eurasian perennial grasses, has caused a dramatic shift in their composition. We know very little about the consequences of this compositional change for the cycling and retention of soil nitrogen - an essential nutrient that limits plant growth in these ecosystems. The aim of this study is to investigate whether differences in nitrogen uptake and use by native perennial grasses, versus Eurasian annual or perennial grasses leads to differences in nitrogen cycling and leaching in plots dominated by each type of grass. We are particularly interested in whether vegetation composition and soil nitrogen cycling interact to make communities resistant to further compositional changes.