Collaborative Research: Effects of Nutrient Stress on a Co-evolved Food Web

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A major challenge for ecologists is to understand the effects that environmental stressors have on community structure and function. This research will determine how a novel stressor - increased atmospheric deposition of nitrogen - is altering the dynamics of the detritus-based food web associated with the northern pitcher plant, Sarracenia purpurea. Three different types of analyses are proposed to address hypotheses related to the trophic dynamics of pitcher plan communities. A field 'pulse' experiment will manipulate the species composition of the food web and the source of nitrogen. Nitrogen isotopes will be used to reveal the movement of nitrogen derived from anthropogenic sources and from prey. A greenhouse 'press' experiment will measure the effects of different food web structures on nutrient uptake and growth of pitcher plants. Experimental results will be used to develop models of community assembly and of food web dynamics. The proposed research will reveal the importance of anthropogenic stressors on co-evolved systems and contribute to a deeper understanding of the contrasting effects of top-down and bottom-up forces on the dynamics of non-equilibrial assemblages. The research will result in general models that can be applied to other ecological communities experiencing novel stressors. It will involve graduate and undergraduate students in supervised and independent research.