Mountain Pine Beetle Cutting Deadly Swath Across The West
BEND, Ore. (AP) _ Swarms of mountain pine beetles are cutting a deadly swath through the West, creating fuel for forest fires as they kill huge, dense plots of trees from Montana to New Mexico and Colorado to California.
The insect, about the size of a big pinhead, destroys about 2 million acres of timber a year nationwide.
Last year it ravaged 2.4 million acres, with more than half of that - 1.4 million acres - on the eastern side of the Cascade Range in Oregon. The year before, 3.4 million acres were wiped out.
By comparison, wildfires have consumed nearly 3.8 million acres this year, an area larger than Connecticut.
″Basically, what we’ve had is a tidal wave rolling down to the south,″ says Dave Bridgwater, an entomologist at the U.S. Forest Service’s regional office in Portland.
The ″wave″ has been rolling through an area of lodgepole pine on the eastern slope of the Cascades in central Oregon. Though it prefers lodgepole, the beetle also attacks more valuable pine species such as ponderosa, sugar, Western white and whitebark.
The result is large parcels of dead trees that amount to a tinderbox.
About 4,000 acres of dead lodgepole helped fuel a fire that consumed more than 11,000 acres in the Deschutes National Forest this summer.
Beetle-killed forest land also was a factor in the massive forest fires in Yellowstone National Park, said Tom Hofacker, an entomologist at the Forest Service’s national headquarters in Rosslyn, Va.
″The lodgepole pine forest is regenerated through these fires,″ said Hofacker. ″In another 80 to 100 years it gets killed again by the mountain pine beetle. Ten to 15 years after that the trees start falling down, and the stage is set for another fire.″
Russ Mitchell, an entomologist in Bend, uses a chisel designed for cracking open human skulls on the autopsy table to dig into the bark of lodgepole pines that are as good as dead.
″I wish I could talk to these things,″ he said, uncovering a male beetle burrowing under the bark toward a female.
Though the tree still looked green and healthy, it will be red and dead by next spring, overwhelmed by hordes of insects and the accompanying fungus that finishes off the trees.
″One tree will be selected by what you might call pioneer beetles,″ said Mitchell. ″The females pick the tree out.″
Trees weakened by a lack of water emit a gas that the beetles can smell, Bridgwater said. The insects also are attracted to the biggest trees in the area, leaving smaller trees alone.
Once the beetle starts boring into bark, it puts out a pheromone, or odor, that attracts other beetles.
Thousands of beetles bore into the tree, enough to overcome the tree’s main line of defense, which is to push the beetles out with heavy flows of sap.
″When the beetle has mated, it will begin to put out another odor,″ said Mitchell. ″It says, ’This place is full.‴
Beetles will move on to another tree. Within three years, they can move through an entire stand.
What actually kills the trees is the fungus, whose spores ride along on the beetle’s back.
Researchers are looking at pheromones as a way of managing the beetles, Mitchell said.
Packets of the ″this place is full″ pheromone could be tacked up to protect trees in campgrounds and seed orchards, and packets of the ″come on in″ pheromone could be placed nearby in a stand slated for logging, he said.
Besides firewood, the dead lodgepole is gaining popularity as a source of paper pulp because dead chips are lighter than green ones.
″I think it’s pretty sure that by the year 2,000, most of the lodgepole pine (in Oregon) will be dead, whether it is harvested or not,″ said Ed Blaydon, a marketing specialist for the four national forests in southeastern Oregon.