Collaborative Research; cold-season gas exchange of arctic plants - resolving winter carbon and water balances of Alaskan arctic tundra
General circulation model results predict that the greatest magnitude of climate warming will occur at high latitudes. In the Arctic region, changes in physical environment (warming permafrost, shrinking ponds) and vegetation change (increased shrubs, flowering in winter) provide strong evidence that is consistent with the changes that are predicted based on the GCM results. However, the status of these ecosystems as a global sink/source of C in the future hinges upon the response of the ecosystem's physiological components (i.e. species photosynthesis, respiration, composition changes) to changes in climate. The vast majority of research on tundra vegetation has focused on physiological processes during the short 2-3 month growing season, with only a handful of studies of physiological processes during the 9-10 month long cold season. These limited cold season investigations have provided evidence that challenge the long standing dogma that conditions in the cold season are too harsh for vascular plant species to be physiologically active. Developing a comprehensive understanding of cold season physiological processes is required to further our understanding of physiological processes of arctic tundra vegetation in the face of rapid climate change.
Intellectual Merit: Our objectives are to 1) fill the large gap in our understanding of physiological processes of arctic tundra vegetation during the cold season, and 2) determine how these physiological processes contribute to the carbon dynamics of the ecosystem under current environmental conditions and scenarios of climate warming. This study is directly relevant to components of the US Global Change Research Program, which seeks to better quantify North American land carbon exchange and processes controlling its dynamics. The novel aspects of this research include a unique combination of approaches used to address: cold season plant physiology, carbon acquisition under snow, carbon turnover, sources of water for the plants during the cold season, mortality, and respiration rate sensitivity to predicted changes in temperature. The results will lead into new insights into plant physiology and carbon dynamics of two tundra ecosystems during the cold season.
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