Wednesday, May 20, 2009 - 8:00 AM
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First-year effects of an unusual tundra fire on an Arctic stream

Elissa B. Schuett1, William B. Bowden2, Angela R. Allen1, Linda Deegan1, and George W. Kling3. (1) Ecosystems Center, Marine Biological Laboratory, 7 MBL St., Woods Hole, MA 02543, (2) Rubenstein School of Natural Resources, University of Vermont, Burlington, VT 05405, (3) Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI 48109

During late summer and early fall 2007 a tundra fire caused by a lightning strike burned approximately 1,000 km2 on the North Slope of Alaska. We wondered how large-scale fires – which may increase in frequency on the tundra as a consequence of arctic climate change – might influence stream ecosystems.  We sampled streams in the burned area during the first snowmelt and growing season after the fire (2008). We compared long-term water chemistry data from the Kuparuk River (an intensively studied 4th order tundra stream about 50 km southeast of the burned area) to a similar river (the “South River”) within the severely burned area. There was a short-term pulse of inorganic nutrients, with the exception of nitrate, during the spring snowmelt (26 May - 3 June 2008) in the South River (mean±SE: 2.5±0.4 µM NH4+; 0±0 µM NO3-;1.3±0.5 µM SRP), but not in the Kuparuk (0.3±0.05 µM NH4+; 1.2±0.3 µM NO3-;0.05±0.01 µM SRP). Nutrient levels in the South River diminished throughout the summer to concentrations similar to those in the Kuparuk River. Given the high severity of the burn in this area we expected a greater short-term response.  However, longer-term responses to a potential increase in thermokarst may be the more important impact.


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