Abstracts
SEARCH Open Science Meeting
October 27, 2003
Seattle, Washington, USA
The Physical and Hydrological Impacts of a Wildfire on an Arctic Tundra Ecosystem, Seward Peninsula, Alaska
Stefan Kooman1, Larry D. Hinzman2
1Water and Environmental Research Center, University of Alaska Fairbanks, 306 Tanana Drive, Duckering Room 454, Fairbanks, Fairbanks, AK, 99775-5860, USA, Phone 907-474-2758, Fax 907-474-7979, fnsk1@uaf.edu
2Water and Environmental Research Center, University of Alaska Fairbanks, 306 Tanana Drive, Duckering Room 437, Fairbanks, AK, 99775-5860, USA, Phone 907-474-7331, Fax 907-474-7979, ffldh@uaf.edu
Alaska is a fire-dominated ecosystem differing from the northern forests of the continental U.S. and Canada in many important aspects. The fire prone areas of Alaska are primarily the interior boreal forest region. The discontinuous nature of the permafrost distribution tends to promote a mosaic of vegetation types with dense forests of fire-prone black spruce and thick organic layers developing in permafrost areas that have not burned in recent history. Fires also occur, on a lower frequency, in the treeless tundra regions of the Seward Peninsula and Yukon Kuskokwim Delta. Although the cause is unknown, fire records demonstrate a marked positive trend in the numbers of fires over the last 50 years in the tundra regions of the Seward Peninsula.
Arctic and boreal ecosystems are important part of the Earth system as it occupies 22% of the land surface. Global circulations models (GCM) indicate that global change will be most noticeable in northern hemispheres. Increased air temperatures are likely to influence vegetation type and the distribution of permafrost. Changes in arctic ecosystems may have consequences for regional and global climate. Global change will probably cause an increase in wildfire return frequency. Wildfires may have drastic impacts on short-term (albedo, evapotranspiration, carbon dioxide flux) as well as long-term effects (transition in ecosystem, carbon dioxide flux, active layer thickness). Effect of wildfires on ecology (vegetation changes and recovery), hydrology (soil moisture dynamics, surface energy balance ) and physics (active layer changes) on boreal ecosystems have been investigated. However, the hydrological impact of wildfires on arctic tundra are less understood.
Meteorological stations with extensive soil instrumentation are operated on the Seward Peninsula in four locations. One of these stations was destroyed in a severe fire in August 2002, resulting in a loss of instrumentation. This created, however, a unique opportunity to monitor the changes of this arctic tundra system following a fire. The damaged equipment was replaced within a few months. A nearly continuous four-year record before and almost one year of measurements after fire has been collected.
The impact of fire on an arctic tundra ecosystem with respect to surface energy balance, subsurface thermal regime and soil moisture dynamics is being investigated. The study characterizes the influence of burn severity on short-term impacts and consequences for long-term recovery. Additional distributed measurements of subsurface moisture and temperature are utilized to investigate the influence of burn severity. Preliminary results will be presented.
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