HR: 12:05h
AN: B42B-06    [Abstracts]
TI: CO$^{2}$ and CH$^{4}$ Exchange in Interior Alaska: Interactions Between Fire, Water, Soils and Vegetation.
AU: * Myers-Smith, I H
EM: ftihm@uaf.edu
AF: Institute of Arctic Biology, 211 Irving I Bldg. University of Alaska Fairbanks, Fairbanks, AK 99775 United States
AU: * Myers-Smith, I H
EM: ftihm@uaf.edu
AF: Alaska Cooperative Fish and Wildlife Research Unit, 209 Irving I Bldg. University of Alaska Fairbanks, Fairbanks, AK 99775 United States
AU: McGuire, A D
EM: ffadm@uaf.edu
AF: Institute of Arctic Biology, 211 Irving I Bldg. University of Alaska Fairbanks, Fairbanks, AK 99775 United States
AU: McGuire, A D
EM: ffadm@uaf.edu
AF: Alaska Cooperative Fish and Wildlife Research Unit, 209 Irving I Bldg. University of Alaska Fairbanks, Fairbanks, AK 99775 United States
AU: Chapin, F S
EM: fffsc@uaf.edu
AF: Institute of Arctic Biology, 211 Irving I Bldg. University of Alaska Fairbanks, Fairbanks, AK 99775 United States
AU: Harden, J W
EM: jharden@usgs.gov
AF: U.S. Geologic Survey, 345 Middlefield Rd., MS 962, Menlo Park, CA 94025 United States
AB: The Alaskan interior contains large carbon reserves stored in poorly drained ecosystems. With warming, these areas of the boreal forest may experience more frequent or extensive stand replacing fires, and thus change the primary factors controlling carbon emissions. In 2001, a low-lying area of the Tanana Flood Plain adjacent to the Bonanza Creek LTER burned. Historical changes in vegetation, hydrology and fire at this site were tracked through macrofossil, charcoal and diatom analysis of peat cores. Dating the charcoal layers in the peat cores indicate four fire events in the past 800 years. The paleoecological record reveals a pattern of expansion of the bog after fire. After the most recent fire, a 30m transect was established along a moisture gradient from the center of a sphagnum dominated collapse feature into the surrounding burn. Thermocarst and subsiding soils were observed on the margin of the sphagnum bog in the three years since the fire. This has increased the anaerobic fraction of the soil profile. CO$^{2}$ flux data suggest that both the dry and wet ends of the moisture gradient are sinks for CO$^{2}$, with a growing season average daytime NEE of -2 $\mu$mol CO$^{2}$ m$^{-2} s$^{-1}$. The moat is a CH$^{4}$ source with an average growing season flux of 30 mg CH$^{4}$ m$^{-2}$ d$^{-1}$ in the abnormally dry summer of 2004. We hypothesize that, after fire, lowland areas become wetter. This leads to high NEP, greater inputs of labile carbon, and increased CH$^{4}$ efflux. However, if interior Alaska experiences more abnormally warm and dry summers like that of 2004, future CH4 production may be suppressed by the changing climate.
DE: 1823 Frozen ground
DE: 1851 Plant ecology
DE: 1866 Soil moisture
DE: 1890 Wetlands
DE: 1615 Biogeochemical processes (4805)
SC: Biogeosciences [B]
MN: 2004 AGU Fall Meeting