State entomologist: Lake Christine Fire burn area ripe for Douglas fir beetle infestation
January 16, 2019
The Roaring Fork Valley forest has largely escaped the bark beetle outbreaks that have plagued many parts of the Colorado mountains in recent years, but that could change because of the Lake Christine Fire.
Colorado State Forest Service entomologist Dan West said the valley already is dealing with pockets of Douglas fir beetle infestations. He expects the problem to expand this year once beetles discover they have a smorgasbord of moderately scorched, living trees within the Lake Christine Fire perimeter.
"It's almost a one-two punch with those fires," West said Tuesday.
First, the fire itself chars acres of trees. Then, surviving but stressed trees become more susceptible to attacks by insects. Douglas fir, spruce and other species weakened within the fire area will likely be targeted, he said.
“It’s almost a one-two punch with those fires.”
— Dan West, Colorado State Forest Service
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"I have a feeling that's going to be a hot spot for years to come," West said, regarding beetle activity.
The Douglas-fir beetles attack the largest trees first. They continue year after year until they either exhaust suitable food sources or the trees are able to fend them off. Drought stresses trees and makes them susceptible. Average and above-average precipitation makes them more resilient.
West said it would be nearly impossible to clear all the moderately stressed trees that may be ripe for beetles from the burn area. Before the partial government shutdown, the Aspen-Sopris Ranger District was working on a plan for hazard tree removal and a salvage timber sale on Basalt Mountain. An extended shutdown could delay the project.
The Colorado State Forest Service performs an aerial health survey of the forests every year in partnership with the Rocky Mountain Region of the U.S. Forest Service. They monitor forest health on millions of acres.
The 2018 survey showed spruce beetle outbreaks in Rocky Mountain National Park and throughout central and southern Colorado are the most glaring statewide problem.
"Since the year 2000, spruce beetle outbreaks have caused tree mortality on more than 1.8 million acres in Colorado, and approximately 40 percent of the spruce-fir forests in Colorado have now been affected," said a report by the state forest service.
In the Roaring Fork Valley, the Douglas-fir beetle is "hands down" the biggest issue, West said.
In Pitkin County, there were an estimated 1,400 acres of forest affected by Douglas-fir beetles in 2018. That is up from 590 acres affected in 2017, according to West.
In Eagle County, the Douglas-fir beetle invaded the Fryingpan Valley and areas around Basalt Mountain, which took the brunt of the Lake Christine Fire's wrath. The Douglas-fir beetle affected 1,500 acres in Eagle County in 2018, mostly in the Roaring Fork watershed. That's up from 500 acres the prior year.
"It's on the march," West said. "It's moving into new areas."
He sees the potential for large growth of the Douglas-fir beetle infestation within the fire scar in 2019 and then branching out, potentially for decades to come. It will be the 12,588-acre fire's lasting legacy.
But West said it's not all "doom and gloom" for the Roaring Fork Valley, a place he regularly visits. The forest overall is healthy because of age and species diversity and differing elevations, West said.
"I see more green than red and dead," he said.
He feels optimistic the health can be maintained and strengthened through proper management, such as forest-thinning projects.
Additional information can be found about the health of Colorado's forests at http://www.csfs.colostate.edu.
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