Beetle infestation hits pockets of forest around Aspen
ASPEN – Small pockets of the national forest around Aspen were hit hard by bark beetles in 2010 but Pitkin County will avoid the infestation that’s ravaged other parts of Colorado, according to experts with the U.S. Forest Service.
The beetle infestation affected another 400,000 acres in Colorado and southern Wyoming last summer, an aerial survey by the Forest Service and Colorado State Forest Service showed. The infestation has spread to about 4 million acres covered in lodgepole pine, five-needle pine and ponderosa pine trees since the outbreak began in 1996, the agencies say.
Jan Burke, a silviculturist with the White River National Forest supervisor’s office, said the forest surrounding the Roaring Fork Valley has natural defenses.
“[The valley] doesn’t have large contiguous areas of the lodgepole pine,” Burke said. “Where you do have [lodgepole], it’s getting hammered.”
The pockets where the infestation is most noticeable include Buttermilk ski area, the south edge of Snowmass ski area, upper Smuggler Mountain and portions of the Fryingpan Valley, particularly around Ruedi Reservoir, said Burke and Roy Mask, a Forest Service entomologist based in Gunnison.
“It’s something that will catch the eye of skiers,” Mask said.
The needles of trees that were infested and died have turned a rust color. Maps from the aerial survey show significant areas of new beetle activity in 2010 to the southwest and south of Aspen. However, Mask said he learned after checking with the aerial survey team that the infestation in the Aspen area affects fewer trees per acre and is spread over a broader area then in places like Summit and Eagle County along Interstate 70 and around Winter Park. In those areas, thousands of contiguous acres of lodgepole pines have been killed. The number of acres infested in Pitkin County wasn’t available.
Former Aspen mayor John Bennett is executive director of a nonprofit organization called For the Forest, which is working to educate people about beetle infestation and what can be done to combat it.
“The place in the valley where I saw dramatic growth [in beetle kill] is Mount Sopris,” Bennett said. The change between summer 2009 and 2010 was visible in the Thomas Lakes area because of the number of trees that died, he said.
Despite those pockets where the beetles have made a buffet of tree stands, the damage is isolated.
“I’m just not anticipating that red landscape,” Burke said, referring to the Roaring Fork Valley.
Mask concurred. “One of the factors that works in favor there is the species diversity,” he said.
The Aspen area has a good mix of lodgepole, subalpine fir and Engelmann spruce at higher elevations, Burke said. Douglas fir and ponderosa pine can be found lower, generally below 9,000 feet.
Burke said all types of trees are vulnerable to various types of bark beetles. Pockets of different types of trees are likely be killed by beetles at different times. The Forest Service has established 5,000 points throughout the 2.3 million-acre White River National Forest where it takes inventory of species diversity and other conditions every so often.
Research indicates that climate change – with later falls and earlier springs – allows beetles to spread over a longer period, Burke said. But it also provides a longer growing season for the next generation of trees that will replace those now dead and dying.
The Forest Service has teamed with the Skico to successfully battle the Douglas fir beetle at Aspen Highlands. Little packets of a pheromone have been tacked onto the mature fir trees in the ski area. Those packets send a chemical scent to beetles with a message that says, “Go away, the inn is full,” Burke said.
For the Forest also teamed with Pitkin County and the city of Aspen to treat lodgepole pines on about 130 acres of 250 acres of open space on lower Smuggler Mountain. Brood trees were cut down and removed before beetles could spread. Pheromone packets were placed on surviving lodgepoles.
“I would call it a dramatic success,” Bennett said of the work.
For result of the state and national forest survey, go to http://www.fs.usda.gov/r2.
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