Contrary to the conventional wisdom, scientists have found that logging big dead trees after a wildfire and planting young ones makes future fires worse, at least for the first 10 or 20 years while the young trees create a volatile new source of fuel.
GRANTS PASS, Ore. -- Contrary to the conventional wisdom, scientists have found that logging big dead trees after a wildfire and planting young ones makes future fires worse, at least for the first 10 or 20 years while the young trees create a volatile new source of fuel.
The findings by scientists from the U.S. Forest Service and Oregon State University raise questions about the long-standing practice of salvage logging on national forests at a time when global warming is expected to increase the size and numbers of wildfires and the annual cost of fighting them is running around $1 billion.
In the first study of its kind, scientists examined satellite images, aerial photographs, and records of logging and replanting to look at areas that burned in the 1987 Silver fire in southwestern Oregon and again in the 2002 Biscuit fire.
"It was the conventional wisdom that salvage logging and planting could reduce the risk of high-severity fires," said Jonathan R. Thompson, a doctoral candidate in forest science at Oregon State, who was lead author of the study appearing this week in Proceedings of the National Academy of Sciences. "Our data suggest otherwise."
They suggested that the large stands of closely packed young trees created by replanting are a much more volatile source of fuel for decades to come than the large dead trees that are cut down and hauled away in salvage logging operations.
"This isn't the full story," added Thomas Spies, a research forester with the U.S. Forest Service Pacific Northwest Research Station, who took part in the study. "It's one more piece of information to help inform the decision process."
Agriculture Undersecretary Mark Rey, who oversees the Forest Service, said the study's findings indicated that on national forests that burn frequently, it would be a good idea to plant young trees farther apart and keep the lower branches pruned to reduce fire danger -- something the Forest Service is starting to do.
Overall, whether to salvage log continues to be a complex decision based on both the economics and the ecology of a specific site, he said.
Greg Aplet, staff scientist for The Wilderness Society, said a recent review of scientific evidence showed that economics -- the value of timber logged after a fire and the jobs that go along with it -- is the only real benefit of salvage logging.
"There is no fuel reduction benefit. There is no ecological benefit to salvage logging," he said from Denver.
Recent studies suggest that as the climate warms and drought persists across the West, wildfire will become more common, that even the most severely burned forests will sprout plentiful seedlings on their own, and that salvage logging can increase future fire danger by leaving more dead fuel on the ground and delay regeneration by killing naturally sprouted seedlings.
The largest wildfire in the nation in 2002 at 500,000 acres, the Biscuit fire has been a battleground between environmentalists and the Bush administration over harvesting trees after fire. Only 5 percent of the area burned was logged afterward.
The political battle has waned with Democrats taking control of Congress. A bill to speed up salvage logging on national forests after wildfires died in Congress last year, and has not been reintroduced.
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