Large swaths of dead pine trees are seen in May in the Sierra National Forest, just south of Yosemite. The central and southern Sierra Nevada have been hit particularly hard by bark beetles, according to the U.S. Forest Service.
TAHOE-TRUCKEE, Calif. — Of the millions of trees that are dead or dying as a result of California’s ongoing drought, about 36,000 are spread across forests in the greater Lake Tahoe-Truckee region.
A U.S. Department of Agriculture report published March 2015 shows that of more than 44 million acres surveyed in California, the tree mortality rate in 2014 more than doubled from the previous year, with about 909,000 acres showing elevated mortality.
More than 10 million trees surveyed in Southern California’s Los Padres National Forest have been impacted by the drought and pine bark beetles, according to the report.
In total, the U.S. Forest Service estimates the current drought has contributed to the death of at least 12.5 million trees in California’s forests.
Of the more than 36,000 reported dead or dying trees in the Tahoe region, 30,370 were viewed within the Tahoe National Forest, which extends east of Sacramento, through the foothills and across the Sierra crest to the California state line.
The remaining 6,106 were viewed within the Lake Tahoe Basin, according to the report. In terms of area, the mapped mortality included about 6,331 acres of forest — 1,842 in Nevada County, and 4,489 in Placer.
“What is happening now, these small pockets are composed of larger trees,” said David Fournier, with the Forest Service’s Lake Tahoe Basin Management Unit.
Foresters and fire people call the dead trees “red trees,” Fournier said — whereas a healthy pine or fir tree will have its typical deep green color, aerial surveys conducted for the annual report show large swaths of forest taking on a brown or red hue.
Despite the fact California has been in this current drought since 2011, Fournier said the state never really recovered from the historic drought conditions in the early to mid-90s.
“Somewhere in the last nine years, (California has) not had a substantial winter, and in the last four years, it’s been nearly non-existent,” he said.
with the beetles
Fournier has worked for USFS since 2002. His studies of bark beetles in the area included the last major outbreak, which began in 1991 and lasted until 1997. Like now, that outbreak coincided with a prolonged drought period.
There are a variety of pine bark beetles in the area, Fournier said, each named after the particular type of wood they prefer.
At Lake Tahoe, the Jeffrey pine beetle — described by USFS as the most serious insect pest of the evergreen trees — is the most prevalent Fournier said.
“It has a unique relationship with the area, as the pine tree is indigenous to this area only,” he said. “It is a native beetle species.”
Ips beetles, meanwhile, infest fir trees, red and white, and Fournier said foresters see a high mortality rate for those trees as well in the Tahoe region. Mountain pine beetles infest sugar pines and lodgepole pines, he added.
Unlike those in Southern California, Lake Tahoe-area evergreens are large and have a greater water need, Fournier said. Without sufficient precipitation, the trees have a more difficult time “pitching the beetles out.”
“Once a beetle is successful at boring in and establishing itself, it emits a pheromone to attract more beetles,” Fournier said.
It’s called a mass attack, he said, adding that due to the high density of trees in a concentrated region, the problem is compounded exponentially.
THINNING THE SOLUTION?
Fournier points to an issue that may seem counter-intuitive to the general public when it comes to answering the question, “how can we save our trees?”
In order to promote healthy forest environments, tree thinning is essential, he said.
As fires and deforestation took their toll on trees over the past several decades in the West, antiquated methods to reforest focused heavily on massive replanting efforts, Fournier said.
However, it was like packing a bunch of children into a house to let them all grow as big as they could. Eventually, space would become an issue. This is analogous to what foresters are facing in the region, Fournier said.
“The public has a lifetime bias (to thinning) — they don’t realize that all of these trees came up in one age group,” he said. “That’s not sustainable.”
Once upon a time, there was a Tahoe forest with many age classes, broken up in a way that one could say it was sustainable, Fournier explained. Now, the area is home to a great proportion of trees the same age.
“We need to restore and differentiate that age class,” Fournier said.
FIRE AS AN ALLY
To look at it another way, we live in a fire environment at Truckee and Lake Tahoe, said Forest Schafer, who is the forester (yes, a forester) with the Incline Village-based North Lake Tahoe Fire Protection District.
“Fire is a natural element in the Tahoe forest,” Schafer said. “Fire would keep our fire-adapted forests thinned and spaced out.”
Fire removes dead accumulations as well as young, less-fire-adapted trees, he said. With fewer trees to compete for water, the ones left can grow strong and be not only less susceptible to fires, but can “pitch out” bark beetles more efficiently.
“... When one tree is susceptible to an insect attack, a forest is susceptible to an insect attack,” Schafer said. “When we thin trees and do defensible space, in a way, we are mimicking that activity that fire would promote.”
While the drought has contributed to alarmingly increased numbers of tree mortality, fires still account for the lion’s share of tree deaths in California, Fournier said.
However, one hand washes the other, so to speak.
“Where you have large bark beetle outbreaks, you have trees predisposed to fire,” Fournier said.
When you have drought stressing, predisposing trees to beetles, Fournier said the amount of fuel on the ground could come in the form of the waste created by the beetles.
“By and large, you wouldn’t see the red trees that were attacked until much later in the fall or even next spring,” Fournier said.
‘A HEALTHY FOREST’
It’s a sentiment NLTFPD Chief Mike Brown shares, especially as the current wildfire season at Lake Tahoe heats up.
“We’re experiencing fires now that we would normally see in August or September,” said Brown, adding that the early start to the fire season has put a draw on available resources — resources that are being outsourced to regions like Alaska and Colorado, which have been hard hit by early season fires as well.
“When fires start this early, there is a draw down for resources,” said Brown, referring to the Washington Fire, which is nearing containment as it burns several miles southeast of Lake Tahoe.
Though the threat persists locally, it’s a responsibility every fire district and state agency shares cooperatively, Fournier said, through the “Multi-Jurisdictional Fuel Reduction, Wildfire Prevention Strategy.”
National, state and local leadership recognize and support the mutual benefits to all jurisdictions working collaboratively to reduce fuels in order to sustain resilient forest landscapes and create fire-adapted communities throughout the Lake Tahoe Basin.
The 2014 update of the strategy emphasizes “continued cooperative fuels treatment strategies to achieve both social and ecological benefits.”
“It’s all of us trying to work together to accomplish the goal of having a more healthy, resilient forest,” Fournier said.
Through a combined effort, these agencies are treating and thinning forests by about 5,000 acres annually, according to the strategy.
“A healthy forest that is resilient to wildfire, it challenges us to treat the forest as opposed to nature doing its thing,” Fournier said. “The more we can do proactively to thin out the forest, the more we can contribute to the natural condition of keeping fuel loading low.”
