Bark Beetles Ravage Drought-stricken Forests in California
Armies of bark beetles are ravaging drought-weakened pine trees forests throughout California in a fast spreading epidemic that biologists fear could soon turn catastrophic.
Local, state and federal officials are helpless against the pestilence, which has turned hundreds of thousands of acres of forest brown and left huge fire-prone stands of dead wood.
The trees are being devoured by millions of native beetles, each about the size of a grain of rice.
The insects, thriving in the warm weather and lack of freezing temperatures, are overwhelming the defenses of water-starved trees, attacking in waves and multiplying fast, depositing eggs under the bark that hatch into hungry larval grubs.
“Things are looking really, really bad,” said a forest pest management specialist for the California Department of Forestry and Fire Protection. “We’ve got native bark beetles that are attacking the pines. They are only successful in attacking the trees when the trees are stressed. Right now all the trees are stressed because of drought.”
The infected trees are on private and public lands, in national parks, wilderness areas and managed forests. There seems to be no solution short of removing the dead and dying trees and hoping for rain and cold weather. The worst of it is in the southern part of the state, but pest management experts say the plague is moving North.
Large numbers of dead pines have been reported in the forested hills above Clear Lake and in some areas of the Sierra around Lake Tahoe, but it is south of the Bay Area where the trees are really going into dying and death mode.
Claifornia state forestry officials estimate that from 20 to 40% of the trees are dead or dying between Calaveras County and the Kings County area near Fresno, with entire hillside forests completely brown.
In Cambria, the picturesque coastal community between Big Sur and San Luis Obispo County, 80 to 85%of the region’s native Monterey pine forest is dead or dying. Tree mortality is also bad in the Tehachapi Mountains, in the far southern region of the state.
It is epidemic and its probably going to get even worse.
Tree deaths are not unusual during sustained hot, dry periods. It happened during previous droughts over the past 40 years.
In Y 2003, then Gov. Gray Davis proclaimed a state of emergency for Los Angeles, Riverside, San Bernardino and San Diego counties because of a bark beetle infestation that at one point threatened more than 6-M acres of California forest.
But experts say this die-off has the potential to be even worse.
The beetle population is normally kept in check by the winter cold, but 3 years of above-average temperatures and lack of snowfall have given the growing beetle hordes free rein to search and destroy.
The regional entomologist for the US Forest Service in California, said bark beetle and drought-caused tree mortality more than 2X’d across forests in California last year and is expected to increase even more this year.
The Forest Service mapped tree mortality across 820,000 acres of forested land in Y 2014 compared with 350,000 acres in Y 2013, according to the service’s annual Aerial Detection Survey Program results.
The drought is impacting many tree species, including oaks and incense cedars, but pine and fir trees are the most obvious victims. Some 460,000 acres with dead or dying fir trees were observed last year by the Forest Service.
There are 19 different types of pines in California, including sugar, ponderosa and lodgepole pine.
Red and white fir are the most common species of fir in California.
Forest pathologists say bark beetle infestations are the primary difference between pine and fir trees and other species that are also suffering ill effects from the drought.
Of the 220 species of bark beetle, about a 12 feed on California pines, including the Western pine beetle, the pine engraver or Pinyon ips and the red turpentine beetle. The beetles attack stressed trees, which have trouble producing enough pitch to drive away the insects. The beetles then release pheromones that attract other beetles, which overwhelm the tree’s defenses.
The different beetle species specialize in certain types of pines and generally stay in specific regions.
The trees on Mount Diablo are being attacked by the California fivespined ips.
Western pine beetles attack ponderosas, but have also been known to dive into Coulter pines.
The mountain pine beetle is wreaking havoc on the lodgepole and ponderosa forests in the Rocky Mountains and in British Columbia.
The insects bore through the pine’s bark where they lay eggs. The larvae then feed on the tree’s living tissue, which cuts off the tree’s ability to transport nutrients. An infestation can involve several thousand beetles, which can then spread to neighboring trees.
The result is that there are now large pockets of California forest, in some cases stretching hundreds of acres, full of mostly dead tinder.
Once frequent fires once controlled the beetle populations in California until flame suppression became a forestry management hallmark.
Although fire officials believe the dead wood from beetle outbreaks increases the likelihood of out-of-control fires, a recent University of Colorado study found that bug-infested forests are no more likely to burn than other forests.
US forestry officials and biologists say the issues are bigger than just fire.
Dying bug-infested forests disrupt the food web, wildlife and local economies. Falling trees have crushed cars and closed campgrounds. The soil in denuded forests can erode away, taking with it forage material for birds, mammals and insects.
The forest health issue that has become a public safety issue.
The situation in California screams for more diligent forest management, including thinning of overcrowded stands of timber, removal of dead trees and clearing of dry brush. All of that costs money, which many property owners cannot spare and legislators are reluctant to part with.
Climate scientists are not sitting idly by while others do all the hand wringing.
As the forests shrink, they say, less CO2 (carbon dioxide) is absorbed, meaning more Greenhouse gases will enter the atmosphere resulting in the acceleration of global warming, researchers said.
Experts say some of the changes to the ecosystem are likely to be permanent unless the weather pattern in the state gets moist soon.
Meanwhile, the drought persists and, as if things weren’t already bad enough, Mother Nature has produced even less rain and snow in California this year than last. It is a situation ripe for hungry beetles, which, create more fuel in a wildfire-prone state.
The California Bark Beetle: Individuals are not much larger than a piece of cooked rice. They survive in trees that are stressed or diseased and cannot secrete enough defensive resin, or sap, to drown the beetles. The beetles emit pheromones that attract other beetles. They lay eggs in the moist inner bark of the tree and the larvae feed on the living tissue, cutting off the tree’s ability to transport nutrients.
Find more information about bark beetle management at: www.fs.usda.gov/main/barkbeetle/barkbeetlemanagement
Remember, when traveling in forests and Fire Danger Zones take extreme care, lives and property depend on it.
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