USA — Wildfire follows hot wind and drought but not the ravaging of mountain pine beetles, a new study found.
University of Colorado scientists investigated western U.S. forests that burned over the past decade and compared them with forests infested with beetles.
They concluded that beetle-killed forests are no more at risk of burning than healthy forests. The beetle outbreaks, which since 1996 have turned 15 million acres of green forest gray from Alaska to Arizona, don’t drive wildfire, said University of Colorado at Boulder ecologist Sarah Hart, author of the study, which is poised for publication this week.
“Forest fuels may get drier as a result of fuels being dead from insect infestations. But the fuels in live forests are dry enough to promote fire. It is weather conditions warm and dry conditions that make the difference,” Hart said.
A peer-reviewed paper is to appear in Proceedings of the National Academy of the Sciences. The National Science Foundation helped fund CU’s 18-month study.
Beetles have ravaged more than 3 million acres in Colorado, mostly thick, higher elevation lodgepole forest far from houses, power lines and roads.
Federal foresters long have linked beetles to increased fire hazards. Congress last year allocated $200 million for tree-thinning on 4.4 million acres of national forest across Western states to control beetle outbreaks and wildfire.
“It’s not going to make a huge difference in terms of the areas burning,” Hart said, noting that recent big fires in Colorado didn’t feed on beetle-killed trees.
U.S. Forest Service research ecologist Matt Jolly said forest managers cannot ignore a tendency of beetle-killed trees to ignite quickly and burn at exceptionally high temperatures. “The way a fire burns is what affects the public,” he said
Thinning dead forests near people, or to protect firefighters, may make sense, Hart said.
But big spending to purge remote dead trees, which can stay standing for up to 40 years, appears pointless, she said. “We don’t need to mess with them if what we’re concerned about is the area burning.”