Project Description: The primary objective of the proposed research is twofold: (1) to develop a mechanistic understanding of how microorganisms process nitrogen (N) in alpine ecosystems and (2) to identify temperature thresholds in alpine microbial community metabolism including nitrogen (N) utilization patterns. The Loch Vale Watershed along the Colorado Front Range is experiencing chronic NO3- loading and simultaneous temperature forcing (Baron and others, 2009). Understanding the microbial response to these simultaneous stressors will yield a more complete understanding of how global change will alter alpine biogeochemistry in the Loch Vale Watershed and across the American West. Alpine ecosystems are the ultimate source of water for many cities and agricultural zones and are especially sensitive to environmental forcing. In the Loch Vale Watershed, increasing temperature due to global warming has been accompanied by increases in mean annual stream NO3- concentrations, which were 50 percent higher for the period 2000 to 2006 compared to the previous nine-year period. While these trends in N most likely reflect a combination of physical, chemical, and biological drivers, how microbes will respond to temperature forcing and concurrent N loading is poorly understood yet is likely to play a key role in alpine biogeochemistry and the ultimate fate of NO3-.
Baron, J.S., Schmidt, T.M., and Hartman, M.D., 2009, Climate-induced changes in high elevation stream nitrate dynamics: Global Change Biology, v. 15, no. 7, p. 1777–1789.