HR: 0800h
AN: B51D-0260    [Abstracts]
TI: Time Scale Dependence of the Environmental and Plant Mediated Controls on Methane Flux From a Temperate Fen
AU: * Treat, C C
EM: cctreat@mtholyoke.edu
AF: Environmental Studies Program, Department of Earth and Environment, Mount Holyoke College, South Hadley, MA 01075 United States
AU: * Treat, C C
EM: cctreat@mtholyoke.edu
AF: Climate Change Research Center, Institute for the Study of Earth, Oceans and Space, University of New Hampshire, Durham, NH 03824 United States
AU: Bubier, J L
EM: jbubier@mtholyoke.edu
AF: Environmental Studies Program, Department of Earth and Environment, Mount Holyoke College, South Hadley, MA 01075 United States
AU: Varner, R K
EM: ruth.varner@unh.edu
AF: Climate Change Research Center, Institute for the Study of Earth, Oceans and Space, University of New Hampshire, Durham, NH 03824 United States
AU: Crill, P
EM: patrick.crill@geo.su.se
AF: Department of Geology and Geochemistry, University of Stockholm, Stockholm, 106 91 Sweden
AB: Global climate change has the potential to greatly affect carbon (C) storage in peatlands, which store about 30% of the pool of global soil carbon. Wetlands may become a larger sink of C if increasing temperatures cause increased plant productivity and C storage. On the other hand, increasing temperatures may cause peatlands to function either as a sink or a source of C to the atmosphere with an increase in respiration and C loss in the form of carbon dioxide (CO₂) and methane (CH₄). This study examined the seasonal and interannual variations in CH₄ emissions and links to plant productivity and environmental conditions in an attempt to determine the controls responsible for the observed spatial and temporal variability of CH₄ flux at the study site. We collected measurements of net ecosystem CO₂ exchange (NEE), CH₄ flux, water table height, and meteorological data from the summer (1 May-31 August) for the years 2000 through 2004 at a temperate peatland in New Hampshire, USA. We observed an increase in photosynthesis and respiration as the summer progressed due to phenological development, temperature, substrate availability, and water table level. CH₄ fluxes also increased in magnitude and variability due to higher peat temperatures leading to a build up of CH₄ in the peat that contributed to the episodic events as the season progressed. We found high interannual variability of CH₄ fluxes and relationships between CH₄ fluxes and variables when we considered instantaneous time scale measurements. However, when considering mean seasonal CH₄ flux over the five-year period, we found low interannual and spatial variability. Species composition affected relationships between CH₄ fluxes and measures of plant productivity (NEE_max, photosynthesis_max, respiration), as well as environmental variables (air temperature, peat temperature, water table level). This suggests a potential shift of factors affecting CH₄ fluxes over different timescales and types of vegetation.
DE: 0414 Biogeochemical cycles, processes, and modeling (0412, 0793, 1615, 4805, 4912)
DE: 0426 Biosphere/atmosphere interactions (0315)
DE: 0428 Carbon cycling (4806)
DE: 0490 Trace gases
SC: Biogeosciences [B]
MN: Fall Meeting 2005