Tiny Beetles Don’t Cause Big Fires


by Cally Carswell 

Vast armies of tiny, tree-killing insects called bark beetles have eaten their way through millions of hectares of pine forest in the western United States since the mid-1990s, leaving the mountains of Colorado, Wyoming, Montana, Idaho, and other states riddled with dead trees. But contrary to popular belief, say the authors of a new study, the beetles aren’t to blame for the record-breaking extent of the wildfires that have torched the region’s forests in recent years.

The study, published online on 23 March in the Proceedings of the National Academy of Sciences, is the first to take a large-scale look at how beetles are affecting the acreage burned across the western United States. Its findings are consistent with earlier research looking at smaller regions and are likely to fuel an ongoing debate over the wisdom of relatively expensive federal efforts to cull insect-damaged trees from western forests, in part to reduce fire risk.

“We examined [an] assumption that’s been made in a lot of policy and management discussions,” says co-author Tom Veblen, a forest and fire ecologist at the University of Colorado, Boulder. “That, as a result of tree-kill by bark beetles, there should be an increase in the aggregate area burned in the western U.S.”

To see if that assumption is correct, the researchers compared U.S. Forest Service maps of forests affected by the mountain pine beetle—the beetle species responsible for the most tree death—with maps of acreage burned during the peak wildfire seasons since 2002. “We were looking to see if there was more area burned in forests that had been infested by mountain pine beetle rather than the live forests,” says lead author Sarah Hart, a University of Colorado postdoctoral researcher.

The result, Hart says: “We did not find any difference.” Specifically, the researchers found that beetles had recently attacked just 5{f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} of the more than 100,000 square kilometers of forest that burned during the 2006, 2007, and 2012 wildfire seasons.

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Source:  Science Magazine



Douglas Complex fires 2013: Rabbit Mount by #ODF, on Flickr
Creative Commons Creative Commons Attribution 2.0 Generic License   by  #ODF 

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