HR: 0800h
AN: B11D-0763    [Abstracts]
TI: A Dynamic Soil Layer Model for Assessing the Effects of Wildfire on High Latitude Terrestrial Ecosystem Dynamics
AU: * Yi, S
EM: ffsy@uaf.edu
AF: Department of Biology and Wildlife University of Alaska Fairbanks, 215 Irving I, Faribanks, AK 99775, United States
AU: McGuire, A D
EM: ffadm@uaf.edu
AF: U.S.Geological Survey,Alaska Cooperative Fish and Wildlife Research Unit, University of Alaska Fairbanks, 214 Irving I, Fairbanks, AK 99775, United States
AU: Harden, J
EM: jharden@usgs.gov
AF: U.S.Geological Survey, 345 Middlefield Road, Menlo Park, CA 94025, United States
AU: Kasischke, E
EM: ekasisch@mail.umd.edu
AF: Department of Geography, University of Maryland, 2181 LeFrak Hall, College Park, MD 20742, United States
AU: Manies, K
EM: kmanies@usgs.gov
AF: U.S.Geological Survey, 345 Middlefield Road, Menlo Park, CA 94025, United States
AU: Hinzman, L
EM: ffldh@uaf.edu
AF: International Arctic Research Center, University of Alaska Fairbanks, Fairbanks, AK 99709, United States
AU: Liljedahl, A
EM: ftakl@uaf.edu
AF: International Arctic Research Center, University of Alaska Fairbanks, Fairbanks, AK 99709, United States
AU: Romanovsky, V
EM: ffver@uaf.edu
AF: Geophysical Institute, University of Alaska Fairbanks, Fairbanks, AK 99775, United States
AU: Marchenko, S
EM: ffssm1@uaf.edu
AF: Geophysical Institute, University of Alaska Fairbanks, Fairbanks, AK 99775, United States
AB: Wildfire is considered an important disturbance to boreal ecosystems in North America. It can affect carbon dynamics directly through combustion emissions, and indirectly through vegetation succession and removal of the surface organic layer, which might accelerate the degradation of permafrost and hence the release of soil carbon. At the regional scale, the direct effects of fire have received a lot of attention, but the evaluation of the indirect effects has been more limited because the appropriate tools have not yet developed for application at the regional scale. In this study, we developed a dynamic soil layer model (DSLM) used in the Terrestrial Ecosystem Model (TEM) to investigate the effects of changes of surface organic layer on soil temperature, moisture, and carbon dynamics. The DSLM consists of (1) a simultaneous heat and water transfer scheme, in which a Two-Directional Stefan Algorithm was used to provide a stable and efficient simulation of soil thermal dynamics in both seasonal frost and permafrost regions; (2) an explicit vertical distribution of soil carbon; (3) a conceptual model of removal of organic layer by wildfire; (4) and a conceptual model of recovery of organic layer after wildfire. DSLM-TEM was calibrated for black spruce, white spruce, deciduous and tundra vegetation types. DSLM-TEM was first tested on a tundra burn site and two black spruce fire chronosequences for its performance on soil temperature and moisture simulation. Several sensitivity tests have then been performed to investigate the effects of different schemes of organic layer removal and recovery on permafrost and carbon dynamics. Initial results showed that: (1) soil temperatures and soil moistures were well simulated; (2) active layer depth was sensitive to the thickness of the organic layer; and (3) the simulated organic layer thickness can reasonably represent the dynamics of soil organic layer development after fire disturbance.
DE: 0428 Carbon cycling (4806)
DE: 0475 Permafrost, cryosphere, and high-latitude processes (0702, 0716)
DE: 1615 Biogeochemical cycles, processes, and modeling (0412, 0414, 0793, 4805, 4912)
SC: Biogeosciences [B]
MN: 2007 Fall Meeting