USA — Though bark beetles are marching into lower elevations and killing ponderosa pines in the foothills of Larimer County, the smattering of dead trees they’ve left behind during the last year or two are likely to have little impact on the upcoming forest fire season.
As the northern Front Range foothills have experienced relatively dry weather in recent weeks, wildfires have been burning near Boulder and also near Grey Rock west of Fort Collins.
Experts said any beetle-killed ponderosa pines probably will not increase the fire danger in those areas, but scientists have conducted few studies on the matter.
“Unfortunately, we haven’t been able to look into that question in the lower elevation forests,” said Jose Negron, research entomologist at the U.S. Forest Service’s Rocky Mountain Research Station in Fort Collins. “We have been studying that in lodgepole (pine forests). There hasn’t been a significant association between where trees die from beetles and where fires occur.”
He said ponderosa pine forests often are less dense than beetle-decimated high-elevation lodgepole pine forests and are less likely to experience a crown fire where the blaze burns into the forest canopy.
Regardless, he said, dry weather is the biggest factor in the severity of a wildfire season, not dead trees.
Steve Segin, a Forest Service regional fire information officer, said that in higher-elevation forests, fire potential increases when beetle-killed trees first die, decreases when the needles fall off and increases again when the dead trees fall to the ground.
But, he said, how that might contribute to catastrophic wildfire in ponderosa pine forests hasn’t been extensively studied.
Rocky Mountain National Park officials are more concerned about the dangers posed by unstable standing dead trees than how much those trees might contribute to wildfires, park spokeswoman Kyle Patterson said.
The park’s most recent major wildfire, 2010’s Cow Creek Fire west of Glen Haven, burned in an area where bark beetles had not yet killed any trees at all.
“From what we’re hearing from the research, the conditions that contribute to fire behavior are a multitude of factors: Tree type, stand density, drought, temperatures and wind,” Patterson said.
Rocky Mountain National Park is beginning a major project that will remove beetle-killed trees that could fall and damage property or hurt people. The park will also apply the insecticide Carbaryl to protect other “high value” trees from the beetles, she said.
The chemical will be applied to about 5,000 trees this year, mostly in developed areas of the park, she said.