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Beetles Take Big Bite Out of Forest

Outdoors: Pines in the San Jacinto Mountains are being killed off by an unusually severe infestation.

April 14, 2002|DEBORAH SULLIVAN BRENNAN | SPECIAL TO THE TIMES

IDYLLWILD — The trouble started as a rust-colored tinge at the top of the pine trees on Jim Johnson's lot in this village.

Johnson, a lifelong resident of the mountain town, knew what would come next and dreaded it. The discoloration seeped downward as bark beetles drained the life from the century-old trees.

Since last fall, an army of insects has invaded coulter and ponderosa and sugar pines in the San Jacinto Mountains. Throughout the forest, trees have withered and died.

"I've seen real bad [infestations] before, but nothing like what's happened now," Johnson said. "It looks like a ... war zone in some places."

Although forestry officials don't know the exact number of trees affected, they say that in some 5- to 10-acre pine stands more than 80% have succumbed to the beetles' attack.

The town, which trades on its alpine image, has seen some of its most treasured assets destroyed. Patches of dead trees splotch the hillsides along California 243, and line the banks of Strawberry Creek behind the town's main shopping plaza.

The U.S. Forest Service and the California Department of Forestry and Fire Protection are removing dead and damaged trees from select spots around town. But they say that on most land the infestation is part of the forest cycle and must simply run its course.

The San Jacinto Mountains have long been vulnerable to beetles, and were declared a "zone of infestation" by the state Board of Forestry in 1972. Idyllwild's problem mirrors similar infestations this year in San Bernardino Mountains communities such as Lake Arrowhead and Big Bear Lake.

"Bark beetles attack and kill stressed trees," said Jon Regelbrugge, lands and resource officer for the San Bernardino National Forest. "They always have and always will."

The trees that fall to beetle infestations enrich the forest floor, and dead trees that remain standing shelter insect-eating birds such as woodpeckers, which in turn check beetle populations, said Laura Merrill, an entomologist with the U.S. Forest Service. But the beetles tip the balance when drought, human development or other conditions weaken the trees.

"In a sense it's natural, and in another sense the extent and magnitude of what we have going on may not be entirely natural, because it's affected by things like fire suppression, cities and towns," Regelbrugge said.

Officials say the overwhelming factor right now is a four-year drought. The previous three years yielded less than two-thirds the average annual rainfall for the area, said Jim Ludy, controller of the Idyllwild Water District. This year's sparse storms have dropped just a third of the year-to-date average. Comparing rainfall over the same period since 1929, "This has been the worst year of all in 70 years," Ludy said.

Though healthy trees can "pitch out" beetles by drowning them in sap, drought-parched pines are hard-pressed to fend off the insects' attack.

The main culprit is the western pine beetle, which bores through the bark and devours the phloem--the moist inner bark that stores and transports nutrients from leaves to roots. There the insects dig egg galleries, where larvae hatch, mature and emerge to infest other trees.

A fungus that follows the beetles deals the trees their fatal blow. Root disease and parasites such as mistletoe can also weaken the trees' defenses.

While drought and disease occur naturally, human activity such as fire suppression, logging and construction can also prime the forest for beetle infestations.

Historic logging operations around Idyllwild cut vast stands of trees in the early 20th century, as five sawmills churned out lumber.

On those sites the current generation of pines sprouted shoulder to shoulder, instead of growing in the sparer, staggered fashion of an uncut forest, said Kevin Turner, a division chief with the state Department of Forestry and Fire Protection. He is stationed in Idyllwild to manage the bark beetle infestation.

Firefighting efforts have quenched the small blazes that normally thin stands, leaving heavy thickets of trees and brush, he said.

"It's too dense," Turner said. "It's exceeded the carrying capacity." Construction of buildings, campgrounds and roads also weaken trees by compacting soil and cutting into root systems, he said.

Such an overgrown, overstressed forest forms a fertile feeding ground for bark beetles, officials say. And the stands of damaged trees pose a risk of searing fire. A normal wild-land fire consumes dried vegetation and thins the forest, but a blaze of beetle-killed trees may immolate it.

Flames sweeping through dried treetops can burn with extraordinary heat and intensity, scalding the soil and incinerating healthy trees along with dead ones, Regelbrugge said.

To reduce the risk that such a fire could damage homes and property, the U.S. Forest Service decided to clear a stand of beetle-killed trees off California 243, Regelbrugge said.

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