ASPEN, Colorado - The forests surrounding Aspen will appear more red and dead by the end of the summer because of the mountain pine beetle infestation, an expert with the White River National Forest supervisor's office said Friday.
Jan Burke, a silviculturist based in Glenwood Springs, said the rapid spreading of the infestation that has killed lodgepole pine trees across 2 million acres of Colorado is just starting to affect Pitkin County.
"I think you're going to see a big difference later this summer," she said.
Mountain pine beetles attack live, mature lodgepole pine trees. The females merge on a tree, bore in and lay their eggs between the bark and the wood. The larvae gnaw away all winter and turn into pupae in the summer. They emerge from brood trees in the warm weather months, and the young adults take flight and start the process anew.
The Roaring Fork Valley's forests will never look as bad as those along the Interstate 70 corridor because the concentration of lodgepole pines isn't as great around Aspen, Burke said. Parts of Eagle, Summit and Grand counties have large, contiguous sections of lodgepole. Pitkin County's forests also have a greater diversity of ages in its lodgepoles.
Nevertheless, there are enough lodgepoles at susceptible ages in the Roaring Fork Valley that the infestation - which turns pine needles red as the trees die - will transform the look of the forests, Burke said.
"It will be evident to a casual observer," she said.
Burke said there is no chance of stopping the infestation. The window for prevention is when only one to three trees per acre are infested. And that window has slammed shut.
Greg Aplet, a senior forest scientist with the Wilderness Society, agreed. "Once an outbreak gets going, there are no known treatments that can influence its spread," he said.
The current beetle epidemic is the greatest ever observed, but it doesn't mean the end to lodgepole stands in Colorado's forests, Aplet said. The forests have undergone dramatic changes before and proven themselves resilient to pine beetle attacks and other problems.
In the Roaring Fork Valley, hot spots for the beetle outbreak include Smuggler Mountain, Independence Pass and Chapman Campground in the upper Fryingpan River basin.
A nonprofit organization called For the Forest is teaming with Aspen and Pitkin County governments to try to slow the outbreak on 120 acres of open space on Smuggler Mountain, the popular backcountry playground east of Aspen. Infested trees and dead or dying hazard trees will be removed. Verbenone, which mimics a pheromone produced by mountain pine beetles, will be applied to live trees to try to preserve them. The faux pheromone is supposed to signal beetles that there is no vacancy in a particular tree. Some experts question the practicality of using verbenone to try to preserve lodgepole pines.
The patch of city/county open space targeted for treatment is adjacent to thousands of acres of national forest on Smuggler Mountain. Burke said the U.S. Forest Service activity will be extremely limited on those adjacent lands. Smuggler Mountain includes lands designated wilderness and roadless, areas where the Forest Service is prohibited "from going stomping around," Burke said.
Therefore, because of the legal limits and questions about effectiveness of treatment, the agency won't take steps to try to slow the beetle outbreak on the lands it manages on Smuggler Mountain. However, it conceivably will remove hazard trees along the one official road into the area.
Removing hazard trees has been the Forest Service's focus in the sprawling Aspen-Sopris Ranger District. Crews have removed dead and dying trees from Chapman Campground in the Fryingpan Valley. Assessments of forest health and the varieties of trees have been or will be conducted in the upper Fryingpan, Basalt Mountain, Independence Pass and the Maroon Bells area.
Burke also anticipated a review under the National Environmental Policy Act over the next year on a salvage operation on the Aspen Skiing Co.'s four ski mountains. Assessments suggest there are lodgepole pines at some concentration level on roughly 800 acres out of a total acreage of 5,300 at the ski areas. Aspen Highlands "has more of an infestation than we'd like at this time," Burke said.
There are lodgepole pines on an estimated 500,000 acres in the White River National Forest, which stretches from south of Aspen to north of Glenwood Springs and from Rifle to Summit County. No estimate was available on the acreage that includes lodgepoles in the Aspen-Sopris District.
The mountain pine beetle isn't to blame for all the dying forests. Burke said scores of dead trees visible on the steep slopes south of Ruedi Reservoir are Douglas firs. They are under attack by a different type of beetle from the one devouring the lodgepole pines, although the red and dead result is the same.