Forest fire studies may give false results

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CORVALLIS, Ore., Feb. 1 (UPI) -- U.S. scientists say they've determined some studies involving the impact of forest fires may have grossly overestimated the amount of carbon dioxide released.

Oregon State University researchers say some past approaches to calculating the impact of forest fires have overestimated the number of live trees that burn up and the amount of CO2 that is released into the atmosphere as a result.

The research focused on the Metolius River Watershed in the central Oregon Cascade Range, where about one-third -- 100,000 acres -- of the area burned in four large fires in 2002-03. Although some previous studies assumed 30 percent of the mass of living trees was consumed during the fires, the new study found only up to 3 percent burned.

Some estimates had suggested one of the Metolius fires released 600 percent more carbon emissions than all other energy and fossil fuel use during 2003 in the state of Oregon. But in the recent investigation, scientists concluded the four fires combined produced only about 2.5 percent of annual statewide carbon emissions.

"A new appreciation needs to be made of what we're calling "pyrodiversity,' or wide variation in fire effects and responses," said Garrett Meigs, a research assistant in OSU's Department of Forest Ecosystems and Society. "And more studies should account for the full gradient of fire effects."

The research appeared recently in the journal Ecosystems.