Forest fire report: Big losses rarer than feared

Forest fire report: Big losses rarer than feared

5 December 2008

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USA — A U.S. Forest Service report indicates that Oregon is losing less forest to major fires than had been feared.

A five-year inventory of federal, state and private forests in Oregon from the U.S. Forest Service Pacific Northwest Research Station shows the amount of forest that burned in the kinds of intense fires that move fast and cause a lot of damage was much smaller than previous analyses had predicted.

Barring a prolonged drought, less than half the forested lands in Oregon are predicted to develop crown fires, and an even smaller fraction, 5 to 15 percent, can be expected to develop active crown fires, a report on the inventory said.

]]>That contradicts studies published in 1999 and 2002, which found that a century of trying to put out every forest fire had left much of the forest with an excessive buildup of fuels that would generate major fires, the report said.

An average of 155,000 acres of forest burned annually between 1995 and 2004, which amounts to 0.51 percent of the 30 million acres of total forest land in Oregon. The high in the period was 2002, a drought year, when 1.90 percent of Oregon’s forest burned, about 570,000 acres.

“Increased media attention to wildfires and a perception among land managers of the need for managing wildland fuels more actively may be generating the impression that the area burned is increasing,” the report said.

In general, the state of Oregon forests is good, said Joseph Donnegan, a Forest Service ecologist who was lead editor of the report. Insect infestations and disease are low, the forests are producing a variety of goods such as lumber and services such as clean water, wildlife habitat and outdoor recreation.

Climate, particularly a prolonged drought, is a much bigger factor in determining the prospects for a bad wildfire year than how much logging has been done, Donnegan said.

Forest ecologists Norman K. Johnson of Oregon State University and Jerry Franklin of the University of Washington agreed.

“On the westside (of the Cascades) … the fire danger is highly overrated (in an historical context),” Franklin wrote in an e-mail.

The work needed to get forests in shape amounts primarily to clearing brush and small trees that serve as ladder fuels, carrying flames from the ground up into the forest canopy, rather than thinning mature trees, Donnegan said.

The problem is that there is little commercial value in the materials produced from such work, except as fuel for biomass generators, which are in short supply in Oregon.

However, the inventory estimated that thinning forests in the Cascades from Hood River to Redding, Calif., and the Klamath and Siskiyou mountains from Roseburg to Redding, Calif., could produce $6 billion to $9 billion dollars worth of fuel for power generation, enough to produce 496 to 1,009 megawatts of electricity over 10 years.


Meanwhile, what conservation groups have been telling the Forest Service for years — old growth forests are less prone to fire than younger forests — was borne out in an analysis of the Biscuit Fire, which burned at varying intensities across 500,000 acres primarily on the Siskiyou National Forest in southwestern Oregon.

The inventory found that more than three-quarters of the land covered in big old trees, both conifers and hardwoods, burned at low intensities, which clean up brush and ladder fuels without killing the large trees.

The places that were hit by hot, intense fire tended to be sites that could not grow big trees, and were covered with brush and smaller trees.

The inventory also found that the national forests are home to almost all the old growth forest left in Oregon, and that old growth forests serve as a carbon sink, storing more carbon pulled from the air by photosynthesis than released through decomposition.

Donnegan said it would be up to society to decide whether old growth forests are more valuable as a tool in combatting global warming than as lumber.

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