Foresters assess bark beetle experiment on Aspen’s Smuggler Mountain
The Aspen Times
Aspen, CO Colorado
ASPEN – Mountain pine beetles have continued to attack lodgepole pines on Aspen’s Smuggler Mountain, but that doesn’t mean an experiment to slow the spread of the destructive insects can’t be deemed a success, according to the lead forester assessing the project.
Four forestry consultants are in the middle of a two-week push to physically examine some 20,000 to 30,000 pines, mostly lodgepoles, to determine whether they’ve been attacked by the beetles. They’re also measuring the diameter of about 9,000 trees and collecting data on how densely trees are packed on hundreds of sample plots as part of an assessment of the condition of the forest within the study area.
Armed with handheld computers equipped with GIS mapping capability, GPS units and a host of other pricey gadgetry, along with sturdy boots and strong legs, the crew of four is tromping through the underbrush and bushwhacking up steep slopes spread over about 300 acres of Smuggler.
The study area, said forester and project leader Jeff Webster, includes open space owned jointly by the city of Aspen and Pitkin County, private property and, for comparison’s sake, adjacent U.S. Forest Service property where nothing was done to deter the beetles from attacking.
Early this summer, 202 lodgepole pines infested with beetle larvae were felled and removed from the project area. Then, verbenone packets were stapled to trees, spaced about every 40 feet, in a 130-acre area. The natural pheromone fools adult beetles into leaving healthy trees alone, sending the message that trees are already infested.
“Everybody is going to ask, well, is it working or not?” Webster said. “Well, we can’t tell you until we look at all the variables.”
There was no expectation that the experiment would completely prevent new infestations within the treated area, according to Webster.
“It’s degrees of success,” he said. “We’re buying time. We’re slowing things down – there’s no doubt in my mind.”
Within the entire study area, the crew has identified 300 to 400 trees that were attacked by beetles either this year or last year. The foresters – two with Jeff Webster Forestry Consulting of Redding, Calif., and two with Chestnut Ridge Forestry Consulting of Cloudcroft, N.M. – can determine when the tree was infected by the advance of the beetles beneath the bark.
Along the adjacent edge of the Forest Service property, outside the project area, the crew has looked for a high incidence of attacks.
“The first question somebody asks is, do you push the beetles onto somebody else’s property?” Webster said. “I haven’t observed it, but it’s one of the questions we’re trying to answer.”
The Aspen project is unique in that it involved both the removal of infested “brood” trees and the application of verbenone over a fairly large area, according to Webster. The results of the effort will be of interest in the forestry community and likely to be published as scientific research.
“We want a valid answer out of this,” he said. “We don’t want somebody’s best guess.”
The data will be analyzed by University of California-Berkeley graduate students and Forest Service biologists, according to Gary Tennenbaum, land steward for the Pitkin County Open Space and Trails program.
“It’s going to be very difficult to say what we did this year was successful,” he told the county Open Space and Trails Board last week. “We’re going to have to make a decision when we see the data. Based on that data, do we feel it’s working?”
The tree removal and verbenone application cost $110,000, with the city and county putting up about $45,000 jointly and For the Forest, a local conservation group that spearheaded the project, funding the remainder.
The follow-up study on the ground by Webster’s crew and analysis of the data will cost about $48,000, to be split equally by the city, county, For the Forest and the private landowner, Tennenbaum said.
The city/county open space on Smuggler provided a large swath of forest on which to try the experiment without facing the approval hurdles presented by federal land. The goal, in addition to determining whether such an effort could be successful, was to protect trees in a popular recreation area.
Mountain pine beetles have left huge swaths of Colorado’s pine forests rust-colored and dead.