Study: Beetles don’t make forests more likely to burn

DENVER — Mountain pine beetles have left vast tracts of dead, dry trees in the West, raising fears that they’re more vulnerable to wildfire outbreaks, but a new study found no evidence that bug-infested forests are more likely to burn than healthy ones.

In a paper released Monday, University of Colorado researchers said weather and terrain are bigger factors in determining whether a forest will burn than beetle invasions.

The findings could provide some comfort to people who live near beetle-infested forests, if those trees are statistically no more likely to burn than healthy forests.

But the study acknowledged that other researchers have found that beetles pose different fire risks. Previous studies by the U.S. Forest Service found that once sparked, beetle-killed trees ignite faster and burn more quickly than healthy trees, posing a danger to firefighters.

The new findings were published in the Proceedings of the National Academy of Sciences. Researchers studied the three worst fire seasons in the past 12 years, when the weather was unusually hot and dry.

The study said beetle outbreaks and wildfires increased at the same time but that drought was behind the worsening fires.

Matt Jolly, a Forest Service research ecologist at the Missoula Fire Sciences Laboratory in Montana, said the findings are valid but stressed that previous research has shown beetles affect fires in other, more threatening ways.

The new study looked at fires in Arizona, California, Colorado, Idaho, Montana, Nevada, New Mexico, Oregon, Utah, Washington and Wyoming. The Forest Service says the mountain pine beetle is also present in Nebraska and South Dakota, but those states weren’t part of the study.