HR: 0800h
AN: B41A-0161    [Abstracts]
TI: Effects of Succession on Carbon and Water Fluxes from Sagebrush Steppe
AU: * Kwon, H
EM: hkwon@sciences.sdsu.edu
AF: Department of Botany, 1000 E. University Ave University of Wyoming, Laramie, WY 82071 United States
AU: Pendall, E
EM: pendall@uwyo.edu
AF: Department of Botany, 1000 E. University Ave University of Wyoming, Laramie, WY 82071 United States
AU: Ewers, B E
EM: beewers@uwyo.edu
AF: Department of Botany, 1000 E. University Ave University of Wyoming, Laramie, WY 82071 United States
AU: Bayless, M K
EM: meagankb@uwyo.edu
AF: Department of Botany, 1000 E. University Ave University of Wyoming, Laramie, WY 82071 United States
AU: Naithani, K
EM: kn77@uwyo.edu
AF: Department of Botany, 1000 E. University Ave University of Wyoming, Laramie, WY 82071 United States
AB: Prescribed burning is a management tool applied to sagebrush rangelands in the western United States to reduce shrub cover, increase forage quality and improve wildlife habitat. The resulting mosaics of vegetation in different stages of recovery (succession) following fire, with patches ranging in size from ~10 to >1000 m², have unknown impacts on the carbon and water cycles. We quantified the impact of changing contributions of mountain big sagebrush and perennial grass fluxes in south-central Wyoming to ecosystem fluxes in response to environmental dynamics through two growing seasons. We used eddy covariance to evaluate the influence of different vegetation cover on the magnitude and variability of carbon dioxide and water vapor fluxes during growing seasons of 2004 and 2005. Carbon was taken up at rates of 1 to 3 g C m^-2 d^-1 in June, and the ecosystem became a C source by mid- to late-July. Net C uptake occurred again in September and October following late summer rains in 2004. Peak growing season rates of C uptake (6-8 μmol m^-2 s^-1) and evapotranspiration (5-7 μmol m^-2 s^-1) compare well with fluxes measured from pure sagebrush stands in a large (4 m diameter) ecosystem gas exchange chamber. The results of this research contribute to a larger project quantifying the effects of vegetation succession on carbon sequestration and water loss in sagebrush steppe.
UR: http://www.uwyo.edu/terra/sagebrush/index.html
DE: 0426 Biosphere/atmosphere interactions (0315)
DE: 0428 Carbon cycling (4806)
DE: 1615 Biogeochemical cycles, processes, and modeling (0412, 0414, 0793, 4805, 4912)
DE: 1632 Land cover change
DE: 1655 Water cycles (1836)
SC: Biogeosciences [B]
MN: Fall Meeting 2005