HR: 09:30h
AN: B41A-07    [PDF]
TI: Land-use change effects on fluxes and isotopic composition of CO$_{2}$ and CH$_{4}$ in Panama, and possible insights into the atmospheric H$_{2}$ cycle
AU: * Pendall, E
EM: pendall@uwyo.edu
AF: University of Wyoming, Department of Botany, Laramie, WY 82071 United States
AU: Schwendenmann, L
EM: lschwen@uwyo.edu
AF: University of Wyoming, Department of Botany, Laramie, WY 82071 United States
AU: Potvin, C
EM: catherine.potvin@mcgill.ca
AF: McGill University, Department of Biology, Montreal, QUE H3A 2T5 Canada
AB: Land-use changes in tropical regions are believed to release a quantity of C to the atmosphere which is similar in magnitude to the entire "missing" sink for anthropogenic CO$_{2}$. Our research attempts to evaluate carbon cycling in three land-cover systems in central Panama: cow pasture, native tree plantation, and undisturbed moist forest. In this ongoing project, we are collecting samples of air from profiles in the stable, nocturnal boundary layer, which is dominated by ecosystem respiration. Samples are analyzed for CO$_{2}$ and its isotopes, CH$_{4}$ and its C isotopic composition, N$_{2}$O, H$_{2}$, CO, and SF$_{6}$. We use a flux-gradient method to estimate ecosystem-scale fluxes of trace gases from soil to the atmosphere. Keeling plot intercepts reflect the respiratory contribution of C3 and C4 biomass under contrasting land cover systems, and how this varies with pronounced wet-dry seasonal cycles. C isotopes of methane and gradients of molecular hydrogen provide insight into the source of methane production from pasture and plantation soils. Rainforest soils, in contrast, are sinks for both atmospheric methane and hydrogen. The process oriented nature of this field experiment will contribute to parameterization of carbon cycle models at a variety of spatial scales.
UR: http://ww2.mcgill.ca/biology/faculty/potvin/sardinilla.htm
DE: 0400 Biogeosciences
DE: 1040 Isotopic composition/chemistry
DE: 1615 Biogeochemical processes (4805)
SC: Biogeosciences [B]
MN: 2003 Fall Meeting