HR: 1340h
AN: B43A-0254    [Abstracts]
TI: On the Heterogeneity of CO2 Production and Efflux at the Watershed Scale, Tenderfoot Creek Experimental Forest, Montana
AU: * Riveros, D A
EM: driveros@montana.edu
AF: Department of Land Resources and Environmental Sciences, Montana State University, 334 Leon Johnson Hall PO Box 173120, Bozeman, MT 59717 United States
AU: Pacific, V J
EM: vpacific@montana.edu
AF: Department of Land Resources and Environmental Sciences, Montana State University, 334 Leon Johnson Hall PO Box 173120, Bozeman, MT 59717 United States
AU: McGlynn, B L
EM: bmcglynn@montana.edu
AF: Department of Land Resources and Environmental Sciences, Montana State University, 334 Leon Johnson Hall PO Box 173120, Bozeman, MT 59717 United States
AU: Welsch, D
EM: dwelsch@frostburg.edu
AF: Department of Geography, Frostburg State University, 211 Gunter Hall, Frostburg, MD 21532 United States
AU: Epstein, H
EM: hee2b@virginia.edu
AF: Department of Environmental Sciences, University of Virginia, 291 McCormick Rd PO Box 400123, Charlottesville, VA 22904 United States
AB: The uncertainties embedded in current estimates of net ecosystem CO₂ exchange (NEE) are well acknowledged. More than two-thirds of total terrestrial C is stored below ground and exchanged to the atmosphere through plant and microbial activity, but the mechanisms of such exchange are not well understood. We investigated the variability of the environmental factors that control CO₂ production to understand the heterogeneity of soil CO₂ concentration and efflux at the watershed scale. We present measurements of CO₂ concentrations and flux over one year in mountainous, complex terrain of the 550-ha Stringer Creek watershed located in the Little Belt Mountains of Central Montana. Our results showed that the interaction of soil moisture and soil temperature plays a major role in controlling CO₂ production and efflux across topographic positions. High temporal resolution measurements showed two main trends in the variability of soil CO₂: short-term (daily) variability controlled mainly by soil temperature, and long-term variability controlled by soil moisture. Long-term soil CO₂ concentration showed similar trends at other sites across the watershed. At upland sites, soil CO₂ concentrations reached their maximum after snowmelt and decreased thereafter. At lowland sites, soil CO₂ concentrations did not peak until the late summer. Similarly, dry upland areas showed a greater relative increase in soil CO₂ concentrations after rewetting events than wet lowland areas. We seek to assess the role of topography in controlling soil temperature, soil moisture and soil nutrient status to measure and model CO₂ production and efflux at the watershed scale. Our results are the first to show watershed-scale concentrations and fluxes of CO₂ over time.
DE: 0414 Biogeochemical cycles, processes, and modeling (0412, 0793, 1615, 4805, 4912)
DE: 0428 Carbon cycling (4806)
DE: 0465 Microbiology: ecology, physiology and genomics (4840)
DE: 4806 Carbon cycling (0428)
SC: Biogeosciences [B]
MN: Fall Meeting 2005