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Bark beetles have been around the West for thousands of years, playing a key role in the cyclical death and regeneration of forests.

But in recent years, the drought, warming temperatures and monolithic stands of trees have fueled an unusual outbreak of the native insects and created vast "ghost forests" the telltale red of death.

In the most ominous sign, the top culprit - the mountain pine beetle - has extended its range into northern and high-elevation territories once too cold for it to survive and is killing off whitebark pines, a key species in the fragile rooftop ecosystem of the Rockies.

But while bark beetles are chewing up much of Montana's trees, forest officials said Thursday there are ways to lessen the ecological, economic and wildfire threats from the voracious insects.

More than 150 people attended a one-day symposium at the University of Montana, where they discussed the causes and impacts of the bark beetle outbreak sweeping the West.

The "Red Tree" meeting focused on the mountain pine beetle, which has infested tens of million of acres from Alaska to New Mexico in recent years.

The outbreak has spread to previously unaffected areas, creating a ripple effect that includes wildlife habitat, water quality, wildfire risks, tourism and other factors.

In Montana, more than 750,000 acres have been killed by mountain pine beetles in recent years.

Jesse Logan, a retired U.S. Forest Service entomologist who has studied bark beetles for three decades, said mountain pine beetles threaten to collapse the whitebark pine ecosystems that anchor Yellowstone National Park and other high-elevation areas.

"It's the perfect storm" of natural and human-caused conditions for the mountain pine beetle to capitalize on, including drought, warming temperatures and wildfire suppression, Logan said. "We're looking at the loss of functionality of these ecosystems."

Bark beetles are a formidable force - often overwhelming their natural predators, the trees' natural defenses and human-control efforts - but forest officials said there is some hope.

Diana Six, a professor of forest entomology and pathology at UM, gave an overview of bark beetle biology and trees' defense mechanisms, including resin, toxins and other chemicals. Of the more than 500 species of bark beetles, only a handful attack healthy trees.

Ken Gibson, an entomologist with the Forest Service in Missoula, said prevention is the key.

Studies show mountain pine beetles prefer monolithic forests, or dense stands of mature, larger-diameter trees of the same species and age.

Bark beetle outbreaks are triggered in those stands when trees are stressed by drought, fire or disease, and when warming temperatures boost beetles' activity level, reproduction and winter survival rates.

Gibson said logging and thinning those stands and replacing them with a mosaic of various tree species, sizes and ages can reduce the chance of a beetle attack.

Other solutions include pheromone chemicals and insecticides. Occasionally effective methods are bark peeling, tarping and burning, he said. Salvaging beetle-killed trees also is important for reducing wildfire risks, he said.

Bark beetles, which reproduce inside the bark of trees, typically live in mid-altitude lodgepole, ponderosa and other forests. Large infestations occur periodically. The last major outbreak of mountain pine beetles in the West was in the late 1970s and 1980s.

But drought and warming temperatures have allowed the insects to dramatically expand their range. Whitebark pines, which also are being killed off by white pine blister rust, stabilize the soil and snowpack and are a key food source for grizzly bears and other wildlife.

Gov. Brian Schweitzer, who gave the keynote address, called on the federal government to follow Montana's aggressive approach at harvesting forests and removing small-diameter trees and fire- and insect-damaged trees from state lands.

He said the Forest Service's ability to aggressively manage its Western lands was hampered by lobbyists, lawyers and bureaucrats in Washington, D.C., whom he derided as "skunks."

Reducing fuels improves forest health, reduces wildfire risks, creates forest and mill jobs, and provides woody biomass material for energy production, Schweitzer said.

Loren Rose, controller at Pyramid Mountain Lumber Co. in Seeley Lake, said economic conditions appear bleak for the forest products industry, which has been hurt by the housing market decline, rising fuel costs and other factors.

He also called for increased thinning of overstocked forests, stands that are susceptible to bark beetle infestation and fire- and beetle-damaged trees while the woods are still marketable.

Reporter John Cramer can be reached at 523-5259 or at johncramer@missoulian.com

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