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Bark beetles ravage forests of Tuolumne County

Four years into the drought, bark beetles did what was expected of them in the conifer woods of Tuolumne County.

They bored into the trunks of moisture-stressed pines, cutting off the trees’ nutrient flow. Millions of dead trees mark the landscape, some of them in towns along Highways 108 and 120.

“This is a nightmare,” said Steve Brink, vice president for public resources at the California Forestry Association. “Dead trees right next to power lines, right next to houses, right next to businesses.”

He spoke on a tour bus making its way Thursday through Twain Harte, Mi-Wuk Village and other locales dealing with the outbreak. The places have long drawn retirees and visitors – many of them from the Northern San Joaquin Valley – with their forested charm. Now folks might wonder when a tree will fall and crush them.

Tuolumne is near the northern edge of a scourge that started in the southern Sierra Nevada and has killed an estimated 66 million trees as of June. Experts on the tour said it could top 100 million by year’s end. The beetles hit hardest in ponderosa pines, not the firs and cedars that also are part of the mixed-conifer belt.

The tour also showcased a new approach to forest management that could produce lumber while reducing the risk of beetles and wildfires.

One of the sponsors was the Tuolumne County Alliance for Resources and Environment, which advocates for more logging to supply the county’s two sawmills. The other was Yosemite-Stanislaus Solutions, a coalition of industry people, environmentalists and others concerned about the Stanislaus National Forest and adjacent Yosemite National Park.

Native bug

The species at issue is the Western pine beetle, a native bug that does little damage in wetter times. The drought has reduced the flows of resin and sap that usually push the invaders out, said Jodi Axelson, an entomologist with the University of California Cooperative Extension in Berkeley.

Pesticides are not practical over the millions of acres of timber, according to the U.S. Forest Service. It takes a couple of cold, wet winters to knock the beetles back – something that has not happened since 2011.

“When they re-emerge in spring, they’re looking for new green trees to attack,” Axelson said.

The national forest is focusing its tree-removal work on those that could topple onto roads, campgrounds and other places people visit, forest Supervisor Jeanne Higgins said. It also has reworked its timber sales to include some of the beetle kill, but the logging is still far less than the industry’s heyday into the 1980s.

Sierra Pacific Industries is cutting beetle-killed trees on its 90,000 or so acres in Tuolumne and Calaveras counties. The problem is that they can decay beyond usefulness for lumber in three to four months, Area Manager Tim Tate said.

The dead trees also can be chipped into fuel that generates electricity, including the Pacific Ultrapower plant near Chinese Camp, but they have been hampered by a lack of long-term contracts with utilities.

$1,000 per tree

Homeowners face an economic burden, too. A single dead tree can cost about $1,000 to take down because of the tight quarters for the work.

Several service clubs and other partners are raising money to pay for tree removal for homeowners who are older than 60 or disabled. A state grant could help with the estimated $2 million cost, said Rick Whybra, a leader in fuel-reduction efforts along Highway 120.

Pacific Gas & Electric Co. pays for removal of trees threatening power lines, including one the tour group witnessed in Mi-Wuk Village. A crane lifted crew member Ruben Romero to the top of a 160-foot ponderosa, which he chain-sawed into 30-foot lengths that were lowered to the ground.

PG&E expects to remove about 77,000 beetle-killed trees in Tuolumne County this year, compared with 13,000 to 15,000 in a normal year, program manager Alisha Lomeli said.

The county government has set aside about $9 million, three-fourths of it from the state, to take down trees along the roads it maintains. County Supervisor Randy Hanvelt said about twice as many are on roads maintained by other entities.

He joined others in saying the reduced logging has left the woods vulnerable to fire and insects.

“The bark beetles are just being bark beetles,” Hanvelt said, “and they are killing our trees.”

Another way

Up at Pinecrest, researchers talked about a major change to the forest thinning projects that have reduced some of the wildfire fuel. They often have left the stands with fairly evenly spaced trees over large expanses. The test plots have diversity in units as small as a quarter-acre – open ground in some places, low-density trees in others, along with the thick clumps favored by spotted owls and certain other wildlife.

The pattern mimics how the forest responded to frequent, low-intensity fires sparked by lightning or Native Americans, said Malcolm North, an ecologist with the Forest Service.

“I think that it’s more in line with the ecological processes that these forests developed with, and because of that, it has greater resilience,” he said.

John Holland: 209-578-2385

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