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Bark beetle threat looms in the Sierra

By Jeff DeLong • Reno Gazzette-Journal• December 1, 2008

Pockets of pines in the Mount Rose area and other stretches of the Carson Range are turning brown -- a disturbing sign that an insect assault that has decimated millions of acres of forests to the east could be headed for the Sierra. Whether that occurs or not, experts say, could likely depend on this winter's weather.

"The potential is there. If we continue with this dry weather, it could pretty much take over," said Gail Durham, forest health specialist with the Nevada Division of Forestry. What could take over is the mountain pine beetle, an insect smaller than a grain of rice that has already destroyed vast swaths of timber in Colorado and other nearby states.

"That little bugger has devastated a lot of property in the Rockies and in Canada," Nevada State Forester Pete Anderson said. "The potential is real high we could have a problem in the Sierra as well."

The threat looms as Nevada has begun to recover from another beetle infestation by the pinyon ips, which killed off millions of acres of pinyon pine until the attack began to slow over the past few years, Anderson said. But other bark beetles, particularly the mountain pine beetle, are waging war against western forests. According to a 2007 report by the Council of Western State Foresters, more than 7 million acres of timber contained dead or dying trees due to beetle assault, with another 22 million acres under the threat of significant mortality over the next 15 years. This level of bark beetle-caused tree mortality is the highest in recorded history, the report said.

Evidence that the problem could be happening locally surfaced in pockets of lodgepole pines around Mount Rose, at Heavenly Mountain Resort near South Lake Tahoe and in the Little Valley area between Reno and Carson City, foresters said.

"It's still at the very beginning stages but we're watching it very closely," Anderson said. "It's pretty grim."

A healthy tree can easily fend off attacks by a few beetles by secreting resin and essentially booting the bugs out of its bark. But when trees are unhealthy in overcrowded stands, particularly when stressed by drought, their defense mechanisms are weakened.