Mountain pine beetles (image) get a bad rap, and understandably so. The grain-of-rice-sized insects are responsible for killing pine trees over tens of millions of acres in the Western U.S. and Canada over the last decade. But contrary to popular belief, these pests may not be to blame for more severe wildfires like those that have recently swept through the region. Instead, weather and topography play a greater role in the ecological severity of fires than these bark-boring beetles. New research led by the University of Wisconsin-Madison and the Washington State Department of Natural Resources provides some of the first rigorous field data to test whether fires that burn in areas impacted by mountain pine beetles are more ecologically severe than in those not attacked by the native bug. In a study published online on September 29, 2014 in PNAS, UW-Madison zoology professor Dr. Monica Turner and her graduate student, Brian Harvey, show that pine beetle outbreaks contributed little to the severity of six wildfires that affected more than 75,000 acres in the Northern Rocky Mountains in 2011. They also show that the beetle outbreaks, which occurred from 2000 through 2010, have not directly impacted post-fire recovery of the forests. The study does not, however, address fire behavior, such as how quickly fires spread or how dangerous they are to fight. While the findings may exonerate the insect scapegoats, they should also help ecosystem managers better respond to changes in the face of climate-driven disturbances, like drought and warmer temperatures. Large, severe fires are typical in the lodgepole pine forests found throughout the region, even without mountain pine beetle outbreaks. However, as the climate has warmed, outbreaks and big fires have both become more common.
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