Wednesday, May 13, 2009

Beetle-killed trees raise fire worries

EDWARDS, Colo. (MTN)—Forest fires have been much on the minds of Colorado's mountain towns of late. Scientists point out that forests can always catch on fire, given certain thresholds of heat and drought. But seeing dead trees has a way of pointing out this obvious potential.

Those dead trees have been conspicuous, owing to an epidemic of mountain pine beetles now in its 13th year. Nearly 2 million acres of lodgepole pine have been affected in Colorado and another 500,000 acres in contiguous areas of southern Wyoming.

Trees remain in their "red and dead" stage for three to four years after being attacked by bark beetles. After that, the needles fall off, exposing the gray trunks of dead trees. Those trees will take 15 to 20 years to blow down. Fire risk heightens both during the red-needle stage and again after the logs have fallen to the forest floor.

Conditions this year have been wetter, making conflagrations such as those seen in 2002 unlikely. Nonetheless, local emergency personnel and others in the Eagle Valley figured it was a good time to do a training exercise. The exercise, explains the Vail Daily, assumes a car had started a large wildfire that threatened homes in the high-end Lake Creek and Cordillera areas, about 20 miles west of Vail, forcing evacuation of residents.

But several scientists have challenged just how much the pine beetle epidemic has elevated the risk of wildfires. A team of scientists headed by Bill Romme of Colorado State University several years ago concluded that the wrong conclusions were being drawn from current bark beetle epidemic.

"The key point about lodgepole pine forests is that they were dense and burned infrequently historically, and they are dense and burn infrequently today."

Last year, geography professor Tom Veblen, of the University of Colorado-Boulder, added new ammunition to the argument. His research found that fires correlated with 500-year cycles of sea-surface temperatures in the North Atlantic Ocean.

The take-home message from that evidence, says Veblen, is that natural cycles dominate. In other words, drought conditions determine when fires occur, and logging and other management has relatively little effect. Creating defensible space around subdivisions makes sense, he says, but massive logging in the name of fire suppression cannot be justified.

The Forest Service admits that much of the beetle-killed forests cannot be harvested, because of wilderness or other designations, but also because slopes are just too steep.

However, Forest Service officials—backed up by elected officials in Colorado—have been regularly lobbying Congress for more money, pointing to the need for tree removal along roads and powerlines, near campgrounds and in urban-wildland interface areas. But the greatest need of all is in municipal watershed areas, regional forester Rick Cables tells Forest Magazine, in the summer 2009 issue. He points out that fires near Denver in the last decade have caused extensive and expensive sedimentation of that city's reservoirs. Other reservoirs for Denver and other water districts are also located among forests hard hit by bark beetles.

While some forests and scientists quibble about the role of logging, new forests are appearing. Regeneration commonly begins three to five years after an area has been logged. But forests also regenerate naturally, and saplings have begun to rise among the dead, needleless trees that remain standing.

"The forest that is coming in is more diverse than the homogenous stands of mature lodgepole that existed before," reports the Sky-Hi Daily News. "Aspen, spruce and fir are regenerating with lodgepole pine. We are beginning the stage of the forest renewing itself."

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