HR: 1340h
AN: B33D-1586    [Abstracts]
TI: Coupled Water and Carbon Exchange Processes in a Sagebrush-Steppe Ecosystem
AU: * Mitra, B
EM: bmitra2@buffalo.edu
AF: Department of Geography University at Buffalo - The State University of New York, 105 Wilkeson Quad, Buffalo, NY 14261, United States
AU: Mackay, D S
AF: Department of Geography University at Buffalo - The State University of New York, 105 Wilkeson Quad, Buffalo, NY 14261, United States
AU: Kwon, H
AF: Department of Botany, University of Wyoming, 1000 E. University Ave., Laramie, WY 82071, United States
AU: Ewers, B E
AF: Department of Botany, University of Wyoming, 1000 E. University Ave., Laramie, WY 82071, United States
AU: Pendall, E
AF: Department of Botany, University of Wyoming, 1000 E. University Ave., Laramie, WY 82071, United States
AB: The sagebrush-steppe ecosystem occupies nearly 43 million ha of semi arid, sage brush dominated land in the Great Basin region of United States and retains one of the largest carbon pools in USA. Eddy covariance data collected over a two month period (June- July, 2005) in the sagebrush-steppe dominated ecosystem in south- central Wyoming have shown soil moisture to be a dominant driver of carbon and water fluxes. As soil moisture decreased in July, non-shrub species senesced, leading to a decrease in photosynthesis and respiration. An integrated hydrology and photosynthesis model with a feedback loop to the soil respiration was developed to simulate the water and carbon fluxes. The working hypothesis was that the microbial and photosynthetic activities associated with sagebrush would be linked to two different soil moisture layers, thus helping to elucidate the dominant drivers of carbon and water fluxes. The model incorporates a two-layer soil moisture logic linking soil surface evaporation and microbial processes to the moisture content at a shallow soil depth and transpiration and photosynthesis to be a function of deeper root zone soil moisture. As the landscape was dominated by sagebrush, non sagebrush and bare soil, simulation was conducted separately for all the three components to obtain the equivalent carbon and water fluxes. While the model has been successful in simulating ET (r2 = 0.82), photosynthesis and respiration at high soil moisture content (theta > 0.15), further analysis into mechanisms behind the relatively poor model performance during periods of low soil moisture will be presented.
DE: 1813 Eco-hydrology
DE: 1843 Land/atmosphere interactions (1218, 1631, 3322)
SC: Biogeosciences [B]
MN: 2007 Fall Meeting