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ALASKA FIRE SPARKS NEW RESEARCH BY ECOSYSTEMS CENTER SCIENTISTS

 

Anaktuvuk River fire on Alaska's North Slope
(Bureau of Land Management photo)

 

The tundra of the Arctic Long Term Ecological Research (LTER) site on the North Slope of Alaska sits above hundreds of meters of frozen ground (permafrost). The scant summer rainfall keeps the tundra moist because of this drainage barrier and because of low evapotranspiration during the cool, often cloudy summers. In the exceptionally dry summer of 2007, however, lightning caused a fire that started on July 16, burned 256,000 acres and continued until the end of September when nearby lakes had already frozen over. 

This was the largest fire in Alaska in 2007 and by far the largest ever recorded north of the Brooks Range. “During the 33 years of research at the site, we have noted only two brief fires; these covered only a few dozen acres,” said John Hobbie, principal investigator on the Arctic LTER project and senior scholar at the Ecosystems Center.

Unlike the gigantic fires in interior Alaska, tundra fires are driven more by unusual climate conditions than fuel availability. Characteristically, flames creep along burning the low-lying vegetation and peaty soils; there is no tall tree canopy and no firebrands so natural barriers like streams and rivers easily stop fires.

The Arctic LTER project site is only 23 miles to the southeast of the fire. There are no roads and the only way to reach the fire site is by ski plane in the winter and helicopter in the summer. Despite logistic difficulties, the LTER project has decided to describe and analyze the aftermath of this fire because it represents an opportunity to study the effects of a major arctic disturbance at the landscape and whole-catchment scale. Gus Shaver, senior scientist at the Ecosystems Center, is leading the fire project. 

The obvious changes will be to the vegetation. If the fire stays on the surface and does not destroy all the organic matter in the upper layers, then some plants will re-sprout in the coming spring, that is, in late May. A more intense fire will burn away the peat and organic-rich soils and the tundra will take centuries to re-vegetate. In addition to changes in the plants and soils, there will be large fire-caused differences in the exchange of energy and CO2 with the atmosphere, and probable changes in the nutrient balance of streams and lakes. The change in the energy balance, caused by changes in surface albedo and insulation by the plant and organic layers, will hasten thawing of the ice inclusions in the permafrost, slumping of soil on hillslopes, and movement of sediments and nutrients into streams and lakes.

The LTER project has obtained Small Grants for Exploratory Research (SGER) funding from the National Science Foundation for logistics costs and for initial sampling of the fire’s impacts. Additional SGER funding will come from the National Ecological Observatory Network program to conduct tests using a series of flux towers to measure carbon, water, and surface energy balance. Not only will this new project allow a long-term investigation of recovery but will also take advantage of a natural experiment at a very large scale.

For more information, see Arctic LTER web site: http://ecosystems.mbl.edu/ARC/