Study: Healthy, beetle-kill forests pose similar fire risks
March 31, 2015
EAGLE COUNTY — As big swaths of forests in the region have turned red, then brown, then gray during the past decade, people looked at the dead trees and wondered if large wildfires were more likely and what additional damage they might cause.
But according to a new study from the University of Colorado, large wildfires are no more likely in forests hit by beetle infestation than in those that are healthy.
The study was published last week in the "Proceedings of the National Academy of Sciences." Using federal maps, the study looked at areas of western forests burned by wildfire in 2006, 2007 and 2012, and took into account which areas had been infested by pine beetles. The areas with beetle-kill accounted for 46 percent of the total area burned.
"The bottom line is that forests infested by the mountain pine beetle are not more likely to burn at a regional scale," researcher Sarah Hart, lead study author, wrote in a release about the report. "We found that alterations in the forest infested by the mountain pine beetle are not as important in fires as overriding drivers like climate and topography."
While other studies have taken a more regional approach to studying the effects of beetle infestations on wildfires, the CU study looked at the entire western U.S. from Alaska to the Southwest. The research team used ground, aircraft and satellite data to create its maps of wildfire burns.
Concerns about beetle-kill damage aside, a persistent drought in the West has created increased fire danger.
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In a release about the study, Hart wrote that she hopes the data will be used for more intelligent public-land management. The national 2014 Farm Bill allocated $200 million to reduce wildfire risk due to insect outbreak and disease. Hart wrote that money should instead be targeted where it's really needed.
"If the money is spent on increasing the safety of firefighters, for example, or protecting homes at risk of burning from forest fires, we think that makes sense," Hart wrote.
Where's the risk?
While the CU report takes a broad look at beetle-kill forests and quantifies the issue, area land managers have said for some time that beetle-kill trees don't necessarily pose a greater wildfire risk, despite the way they look.
"All trees fall eventually," said Scott Fitzwilliams, White River National Forest supervisor.
Having all those trees fall at once creates some risk, but Fitzwilliams said the fire danger was greater when the trees were in their first stages of red. Brown trees aren't as big a fire danger.
While efforts to continue to pull dead trees out of forests — with uses including furniture, lumber and fuel for the biomass-fueled electric-generation plant in Gypsum — Fitzwilliams said there's no practical way to pull all of those trees out of the forest. In addition, federal money to do so has declined in the past couple of years.
The focus, Fitzwilliams said, is on what land managers call the "wildland-urban interface" — where forests meet homes. Fitzwilliams said the goal is to avoid what he called "pixie stix" — dead, standing, denuded trees in that interface.
During a tour of the forest north of Vail last year, district ranger Dave Neely said that dead trees are an important part of the life cycle of a forest, so dealing with every dead tree would be counterproductive.
New Vail Fire Chief Mark Novak came here from the Lake Tahoe area, so he's familiar with forests hit hard by drought, disease and insects. While he had glanced at the CU study, Novak said he hoped that the findings don't encourage complacency about wildfire.
"Regardless of whether a fire is in dead trees or not, the community is still at risk," Novak said. "It doesn't take a huge fire to destroy a lot of homes."