Ongoing drought increases bark beetles population in Nevada County, experts say
Sam Gitchel watches warily as more trees in his neighborhood turn brown.
What has the Nevada City resident concerned is a vicious natural cycle, made worse by the ongoing drought across the state.
The number of dead trees are growing and more plants are becoming over-stressed and ideal victims to bark beetles. The pests dry up more vegetation, which add fuel to wildfires and cause more healthy trees to be decimated by more bark beetles.
Experts say the persistent dry spell in California has created a larger-than-ever army of bark beetles that have made their home in the Sierra foothills region. By cutting off a tree’s supply of food and water, these black, hard-shelled insects wreak havoc on drought-weakened pine trees.
“If they are close to the road, they will fall down; and they are most likely to fall down on the road when there is a wildfire and when there is a storm,” said Gitchel, who heads the Greater Champion Mine Firewise Community west of Nevada City. “That is the time when we need our emergency routes for vehicles to come in.”
Gitchel and his friend, Randall Frizzell, started putting together an inventory in November. The two counted as many as 62 dead trees in the Greater Champion Mine area, but even more trees were turning brown as they surveyed the neighborhood.
“I suspect that by the end of the summer, there will be many more dead trees,” said Frizzell.
Gitchel and Frizzell, who sense that this serious problem is happening all over the county, brought it to the attention of the authorities. Their effort prompted Nevada County Department of Public Works and California Department of Forestry and Fire Protection to organize a joint training of hazard tree removal. The task force, led by Road Superintendent Dave Keck, took down 15 dead trees on the county right-of-way along the Old Downieville Highway and Champion Mine Road area from Tuesday to Thursday.
The group’s endeavor reflects the epidemic of bark beetles, a bug that has been a part of the ecosystem of California for eons but has recently become a menace that decimates forests.
Bark beetles are no bigger than a grain of rice in size, but they have the capacity to destroy robust timber in as little as two to four weeks. By laying their larvae in the inner bark, the bugs cut off the nutrient flow of the trees. As an attack progresses, the bark beetles can release chemicals that attract other beetles, engendering a mass attack on the plant. In addition, invasion can spread to neighboring vegetation, causing pockets of trees to disappear in a short amount of time.
“The bark beetles outbreak is going in cycles; it’s going to take a year or two of good winters for the beetles to wind down,” said Michael Woodbridge, public affairs officer for Tahoe National Forest branch of the USDA Forest Service.
Despite a wetter winter that resulted in increased snow pack in the Sierra foothills region, these bug hordes are not likely to subside for several years, as more over-stressed pine stands are succumbing, officials said.
Frizzell is one of the local residents to feel the effect of the insects. Besides his role in assisting Gitchel with the Greater Champion Mine Firewise Community, Frizzell works as an arborist in Nevada City.
“I have been watching an increase (in the number of dead trees) locally for three or four years. Last year was the worst year I’ve witnessed in my career,” said Frizzell, who has worked in the region since 1976.
Frizzell predicts a hike in mortality.
“We will still see mortality this summer, because there are so many beetles,” said Frizzell. “They will probably come out of their winter phrase in May.”
According to experts, bark beetles are a natural part of the ecosystem in California. A tree is able to fend off the pests when it is healthy by producing resinous pitch. But when trees become over-stressed due to the limited soil moisture, they are unable to “pitch out” the invading bark beetles.
The infestation is killing large swaths of forested land, which then become more susceptible to wildfire or causing pine trees to fall. Frizzell said several pines killed by bark beetles have fallen across Old Downieville Highway recently. The bark beetle population is so large now that they can attack in great numbers and kill even healthy pines.
“Bark beetles are not much of a problem normally. It’s during multiple years of drought, that they become a problem,” Frizzell added.
According to an aerial study published by the USDA Forest Service in 2014, over 820,000 acres of land suffered from increased tree mortality due to the assault of bark beetles. That number more than doubled the 350,000 acres reported in 2013.
Woodbridge said a report published by the agency indicated that the western pine beetle activity in Tahoe National Forest’s Yuba River Ranger District has increased dramatically in the last year. The Yuba district spans an area from Downieville to Interstate 80, so western Nevada County is part of the district, Woodbridge said. The same study also revealed bad news on Ponderosa pine, one of the predominant pine species in the community.
“Ponderosa pine mortality is expected to increase in 2016, and with continued drought, has the potential to reach epidemic levels similar in intensity to the current outbreak in the southern Sierra Nevada forests,” the report states.
Woodbridge said the Tahoe region is not used to seeing voracious attacks by bark beetle, until recently.
“We have isolated patches here and there, but they have definitely increased in the last 12 and six months,” said Woodbridge. “We will see how it unfolds.”
Steve Garcia, a Cal Fire Unit forester for Nevada, Yuba and Placer counties, told The Union that deferred forest management, coupled with drought and bark beetle, have resulted into the conditions today.
“Forest management doesn’t occur as regularly as it needs to … it’s costly,” Garcia said. “It’s a cultural element. People don’t view forest as working landscape anymore.”
Joanne Drummond, the executive director of Fire Safe Council of Nevada County, agreed.
“This not a unique problem. This is a routine issue due to lack of moisture and overstocking of timber,” said Drummond. “Trying to manage your forest health and fire safety is a mutual objective. Since we live in the forest, the health of the forest is important to be more resilient to wildfire.”
The Fire Safe Council, a nonprofit formed by citizens in 1998 to reduce fire danger for Nevada County residents, has been educating people on this issue for several years, Drummond said. She encouraged residents to take a more proactive role.
But for the problem to cease completely, experts said nature will have to take its course.
“As spring warms, you are going to see more mortality,” Drummond concurred. “It’s going to get worse, before it gets better.”
For more information on bark beetles and its prevention, please visit: http://www.fs.usda.gov/Internet/FSE_DOCUMENTS/stelprdb5384837.pdf or http://www.readyforwildfire.org/Bark_Beetles_Risk/
To contact Staff Writer Teresa Yinmeng Liu, please call 530-477-4236, or email email@example.com
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