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Sample Analyses
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Sample Analyses

July 14, 2010
Sample Analyses Shikha Sharma analyzes samples for stable isotopes of carbon and nitrogen and % N in the Stable Isotope Facility at the University of Wyoming. [See Related Image.] More about this Image The large and rapid rise in atmospheric carbon dioxide (CO2) concentration due to human activity and associated global warming has the potential to alter Earth's climate system and affect terrestrial ecosystems. An important source of uncertainty in predictions about atmospheric change is how plants will respond to increasing atmospheric carbon dioxide and how climate changes interact with rising CO2 concentrations to affect plant growth and photosynthesis. We are examining effects of elevated CO2 on photosynthesis of trees and invasive weeds in Yellowstone National Park by taking advantage of natural gradients in atmospheric CO2 concentration produced near geological CO2 springs. We are tracing the unique radiocarbon (14C) signature in CO2 taken up by these plants from geological sources as a way to characterize the long-term exposure of plants to elevated CO2. Photosynthetic responses of plants are then estimated from the stable carbon (13C) and oxygen (18O) isotope ratios in plant leaves. Our initial observations reveal the potential for contrasting responses to elevated CO2 between the dominant tree species in Yellowstone National Park--the lodgepole pine, and a noxious invasive forb--the Dalmation toadflax. Further investigation involving more widespread sampling and experimental manipulations of soil resources will provide valuable information about how vegetation in the Greater Yellowstone Ecosystem is likely to respond to future atmospheric changes. Of particular relevance is how elevated CO2 will alter the nutritional quality of vegetation sustaining Bison, Elk and other key wildlife species in Yellowstone. This research was supported by a grant from the National Science Foundation EPSCoR (Experimental Program to Stimulate Competitive Research) Program grant EPS 04-47681, Wyoming NSF EPSCoR Infrastructure Improvement Project, project director Randolph V. Lewis. Dr. Shikha Sharma was hired to serve as co-director of the Stable Isotope Facility under this grant. Her position will be fully funded by the University of Wyoming by the end of this grant. SIP is one of three research facilities to be strengthened or initiated under this EPSCoR award. Funding for this particular segment of the research was also provided by a University of Wyoming Research Office  Faculty Grant-in-Aid Award to Dr. Sharma. (Date of Image: Dec. 2005-2006)


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