International Research Fellowship Program: The Impact of Adaptive Strategies of Below Ground Water and Biogeochemical Cycling and Their Thermody Namic Implications

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0900556DrewryThis award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).The International Research Fellowship Program enables U.S. scientists and engineers to conduct nine to twenty-four months of research abroad. The program's awards provide opportunities for joint research, and the use of unique or complementary facilities, expertise and experimental conditions abroad.This award will support an eighteen-month research fellowship by Dr. Darren T. Drewry to work with Dr. Axel Kleidon at Max Planck Institute for Biogeochemistry in Jena, Germany.Belowground processes play a critical role in hydrologic and carbon cycling on land. Root systems of vegetation have been shown to extend tens of meters into the soil to forage for moisture and nutrients that control plant growth and energy exchange with the atmosphere. The observed passive redistribution of moisture between dry and wet soil layers by root systems may provide an adaptive advantage under water-limited conditions. Tightly coupled to root function are biogeochemical processes, particularly microbial transformations of carbon and nitrogen from organic litter to inorganic minerals that are necessary for a variety of plant functions including photosynthesis. Vegetation modification of below-ground biogeochemical function can thus impact the long-term fitness and competitive advantage of the vegetation itself. Motivated by the need to enhance the predictive capabilities of state-of-the-art Earth-system models, several key ecohydrological and biogeochemical processes that govern ecosystem function and evolution are being incorporated into an existing dynamic global vegetation model. The vegetation model is capable of accounting for diversity in vegetation form and function within a simulation pixel. This allows for hypotheses centered on the role of root processes and their interactions with biogeochemical cycles on global vegetation dynamics and biodiversity to be tested over decadal or century timescales. Through coupling to a general circulation model, which simulates the global atmospheric flow and composition, an analysis of the sensitivity of atmospheric circulation patterns, and key variables such as the temporal and spatial distribution of precipitation, can be performed. The research conducted here has broad implications for fundamental questions about how vegetated land surfaces modulate the global hydrological and biogeochemical cycles, and hence global climate. This work will have practical implications for understanding the impacts of anthropogenic and natural landscape modification on global climate change.