The drive into the Sierra Nevada region of Tuolumne County is peaceful and surrounded by picturesque scenery. But trekking deeper into the woods provides a more disconcerting visual.
Drought, bark beetle and other stresses have contributed to massive tree mortality, as detailed by the California State Association of Counties (CSAC), with an estimated 29 million tree deaths in California.
Earlier this week, the California Governor’s Office of Emergency Services (Cal OES) joined multiple agencies, including Cal Fire and PG&E, to initiate a tree removal project near Sonora in Tuolumne County.
“It takes a lot of time to remove trees and you can see how dangerous these trees are,” said Cal OES Assistant Director of Recovery Charles Rabamad, who toured the project on June 9 in the small town of Twain Harte. “Obviously the collaborative effort is great to see.”
The entire process of removing trees and shipping them to a nearby wood yard usually consumes about 2 hours per load. The three-hour tour Thursday morning consisted of four different stops to view each of the steps for removing trees and the subsequent cleanup process.
Though the cost of each tree removal ranges between $300-$5,000, Rabamad says it’s “well worth it.”
“When it goes beyond the county level, we’re responsible,” he added. “From the recovery side it’s our responsibility to provide technical expertise and funding.”
Another threat that dead trees pose is the proximity to nearby power lines. Up to 30,000 dead trees were found each year, according to PG&E. Now, due to drought-stricken conditions, that number increases to 160,000 annually.
Tree maintenance, or complete removal, was typically done once per year pre-drought, but is now scheduled at least twice a year. To remove large trees, contractors are able to cut 60-foot sections at a time.
“The greatest risk is wildfire,” said Corey Peters, a PG&E Program Manager who oversaw the tree removal project near power lines. “The amount of personal property and personal safety is at risk.”
Bark beetles are often attracted to trees that are already weakened by drought. Dead trees create a potential large amount of hazards around forests, campgrounds, along roads and power lines and increases risks of expansive wildfires. The combination of dry, heat and drought-stricken conditions cause extreme fire dangers and the potential for wildfires to spread more rapidly.
While bark beetles are a normal part of the ecosystems, trees are typically unable to fend off attacks in high-stress situations, such as drought. There are more than 600 species of bark beetles in the United States, with 200 of those detected in California alone.
In years of normal or above precipitation, there is generally modest bark beetle activity. With a prolonged drought and stress being put on trees, the population of bark beetles increases and capitalizes on the weakened conditions.
The potential of bark beetles lingering post-drought is likely for an additional 3-5 years before a decrease is noticeable. What it does is add fuel to already extremely flammable vegetation.
“The removal and disposal of dead and dying trees is very intricate and is really important for us to see firsthand,” said Peter Crase, a Project Manager for the Cal OES Recovery Division who accompanied Rabamad for the tour.
Early signs of tree mortality consist of when the colors of leaves change from a healthy green to a red or brown tinge. Removing dead trees reduce the risk of wildfires around property or homes.
Cal Fire provides the following signs of bark beetle infestation:
- Trees react by releasing pitch as their natural defense against bark beetle attack. This response from the tree will leave small white or reddish-brown pitch tubes on the outside of the bark. A white pitch tube means the beetle was successfully repelled by the tree. If the pitch tube is reddish brown, most likely the beetle was successful in attacking the tree.
- The pitch is accompanied by a sawdust-like substance, called frass, created by bark beetles and their larvae as they borethrough the bark.
- Frass has accumulated in tree crevices and may have fallen to the ground, resembling very fine, reddish-brown coffee ground material at the base of the tree.
- Bark flaking or holes in the bark caused by woodpeckers foraging for bark beetles are also a good indicator that bark beetles are present.
- Removing bark sections will reveal holes created by bark beetles, as well as dead or degraded inner bark.
In leaves or needles
- The needles on conifer trees, like pines, begin to turn a reddish-brown color. Often the change begins at the top of the trees and moves down.
- Some trees may slowly fade in color from green to brown.
- Some trees may die within a few weeks of infestation, but may not show yellow-green, fading or red foliage for several months. Other types of trees may survive years before dying; by the time a tree appears dead, it cannot be saved.
The Tree Mortality Task Force is comprised of state and federal agencies, local governments, utilities, and various stakeholders that coordinate emergency protective actions and monitor ongoing conditions to address the vast tree mortality resulting from four-plus years of unprecedented drought and the resulting bark beetle infestations across large regions of the state.
“As you can imagine, yesterday was a culmination of many months’ worth of work for all of us, from the State Task Force to the local level,” said Tracie Riggs, Tuolumne County Deputy County Administrator. “It is only through strong collaboration and partnerships that we will be able to make a difference. We can do so much more together than we can ever do alone. Tuolumne County is thankful for the support of Cal OES and Cal Fire. Both have been the primary reason we have fared so well through the Rim Fire, the drought and now tree mortality.”