Primary Production in Arctic Ecosystems: Interacting Mechanisms of Adjustment to Climate Change"

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The aim of this research is to analyze the role of temperature, light, and nutrient availability in regulating primary production of arctic tundra ecosytems at several levels of ecological organization and at different time scales. The research is organized around three general hypotheses about the mechanisms reeulating adjustments of primary production in response to short- and long-term variation in climate. The basic idea is that different mechanisms control the responses to climate at different levels of ecological organization and at different time scales. In order to obtain useful predictions of the effects of climate change on primary production, a better understanding of relationships between these interacting mechanisms of adjustment to climate change is needed. To test the three general hypotheses, this five-year program of research will focus on an integrated series of field experiments in moist tussock tundra at Toolik Lake, Alaska. The mechanisms to be studied include those operating at the physiological level (e.g., photosynthesis), the whole-plant level (storage and recycling, changes in allocation and biomass turnover), the species and ecotype levels (constraints on nutrient use eficiency and growth rates), and the whole-ecosystem level (climate controls on soil nutrient supply). This project is part of International Tundra Experiment (ITEX). It is funded within the Arctic System Science (ARCSS) Program. Collaboration with other ecologist working at Toolik Lake and at other arctic sites as part of the Long-Term Ecological research (LTER) and Global Change in Terrestrial Ecosystems (GCTE) programs will increase the application and impact of this research.