Bark beetles are decimating California’s parched forests
The remains of fallen trees, covered with sheets of white plastic on the forest floor, looked like corpses in a morgue. It was actually a quarantine.
That’s an option for rural landowners with burgeoning bark beetle infestations: Cut down the trees, chop the wood, cover it and hope the insects don’t escape—or, even better, cook to death under the plastic—before burning the pile in the winter. It works OK if the outbreak is limited to a small stand of pine trees, but if it’s more widespread, there’s no stopping the swarm, Jeff Webster explained.
“If the trees are still green but infested with beetles, they’re already dead. They just don’t know it yet,” he said.
Webster is senior forester with the Jefferson Resource Co., a consulting firm based in Weed. He recently guided the CN&R through the woods outside of Manton, a town that’s little more than a general store straddling the borders of Tehama and Shasta counties. On his clients’ properties in the foothills, he maintains mere slivers of the coniferous forests that cover much of the Western United States, but in his career he’s traversed backcountry from the Rocky Mountains to the Pacific Ocean.
As a result, he’s had a ground-level perspective on California’s growing problem with drought, bark beetles and dead trees. “It’s amazing,” he said, “how something as small as a grain of rice can cause so much damage.”
In October 2015, Gov. Jerry Brown called the phenomenon “the worst epidemic of tree mortality” in California’s recorded history and declared a state of emergency. At the time, the U.S. Forest Service estimated 22 million trees were dead.
As of Nov. 18, a little more than a year later, the estimate had risen to 102 million trees, mostly in 10 counties in the southern and central Sierra Nevada. For perspective, there are some 4.1 billion live trees statewide. Bark beetles have killed about 2.5 percent of the forests, and roughly 62 million trees died this year alone.
Mass tree mortality is moving north, according to the state’s aerial surveys. Field experts say it’s impossible to predict the impact on the North State, and locally, the beetles have infested only isolated pockets no larger than a couple of acres. Still, worrisome signs are emerging throughout Butte County, says Dave Derby, a forester for Cal Fire based in Magalia. There are groves of snags—dead or dying trees—near Feather Falls, Forest Ranch and communities on the Ridge, and they’re already presenting practical, logistical and financial issues for homeowners, government and the timber industry.
“This is what the central Sierras looked like a few years ago—little patches here and there,” Derby said. Over the last two years, some stands have lost up to 95 percent of pine trees; now, once-lush forests are all brown needles.
“You wonder,” he said, “is this going to happen to us?”Meet the beetles
It’s a common misconception that climate change is pushing the bark beetles north, introducing a new wave of invasive insects. It’s true that changing weather patterns are exacerbating the problem, but the beetles aren’t migrating—they’ve always been a part of the natural balance of forest systems.
Christopher Fettig holds a doctorate in entomology and works at the U.S. Forest Service’s Pacific Southwest Research Station in Alameda County. He spoke to the CN&R by phone.
“A lot of people talk about ‘the bark beetle’ as if there was one individual species responsible for everything that’s going on, but they’re actually a large, diverse group,” he said. “There are greater than 6,000 species in the world, and we have greater than 550 in North America alone.”
In the West, about 15 species of bark beetle are capable of killing large swaths of forest under the right conditions.
The main culprit, in this case, is the aggressive western pine beetle, and its host of choice is the ponderosa pine, a species of large-diameter evergreens found abundantly in California and as far north as British Columbia, Canada.
Again, the beetles aren’t advancing; more trees are succumbing to them. The factors are innumerable, but the simple explanation is that the forests are compromised, having suffered five years of drought on top of being old and overstocked.
Webster compared dense tree stands to people in a refugee camp: “If you put too many people in that camp, and they don’t have enough food and water, what happens? They get sick and die. Well, you get too many trees in a certain area and there aren’t enough resources to go around. The bark beetle becomes the thinning agent.”
Needless to say, millions of acres of standing dead trees represent an enormous fire hazard (see “All fire on the western front,” feature story by Alastair Bland, July 28). Paradoxically, the density problem is largely due to decades of effective wildfire suppression, Webster and Fettig agreed.
“Some of the policies … changed these fire-dependent ecosystems, and as a result we’re seeing much different stand compositions,” Fettig said. “These trees are really, really stressed, and the bark beetles are taking advantage.”
Colonization begins when one scout beetle lands on a tree and bores into the bark. A healthy tree defends itself from the attack with “pitch tubes,” excretions of resin that resemble kernels of popcorn.
“The tree is trying to encapsulate those pioneering individuals in that pitch and kill them,” Fettig said.
A tree’s defenses fail if it’s unhealthy or the swarm of insects is overwhelming. A successful colonization cuts off the tree’s ability to transport water and nutrients, as well as introduces a blue stain fungal infection that prevents the tree from producing resin and “gives the beetle a competitive advantage,” Fettig said.
Eventually, the host tree will die, but the snag could stay upright for years. And here’s where this gets important for people: In the last decade or so, bark beetle outbreaks have been documented across the West, from Southern California to Alaska, but this one stands out because it’s killing large-diameter trees close to homes, communities, roadways, power lines and other infrastructure.
The problem is, where will those trees land when they fall?Timber
This spring, Cheryl Short, 72, noticed that two pine trees on her half-acre property in Magalia weren’t looking all that chipper, then watched their condition deteriorate in a matter of weeks.
“They just died so fast,” she told the CN&R, adding that the die-off wasn’t limited to her homestead. “[The bark beetles] went through the neighborhood quickly, got a few of us roughly around the same time.”
One of the trees is more than 80 feet tall, Short estimates, and roughly 40 feet away from her back porch. “There’s no question—if it falls, it could hit either my neighbor’s house or my house,” she said, “and I’m responsible for that.”
A tree-cutter estimated that he’d charge $700 to $800 to remove both trees, Short said. As a retired widow, she currently can’t afford to have the trees removed.
Elsewhere in the county, Brenda Rightmyer had a similar experience in April. Bark beetles killed seven trees on the back of her 11-acre property in Yankee Hill, and though they weren’t in danger of damaging anything, she decided to remove them anyway. She found a good deal, mostly because she’s in the business as managing director of the Yankee Hill Fire Safe Council, and paid only $1,000 to have the trees felled. However, she couldn’t find anywhere to take the woody refuse, so she paid another $3,500 for a contractor with a portable mill to process it on her land.
“It’s not an easy, inexpensive thing to deal with,” she said.
There’s a growing burden on local government, too. For the county, the top priority is keeping public rights of way clear, which won’t be cheap.
The Butte County Tree Mortality Task Force, formed in June, is made up of representatives from various stakeholders, including the county, Cal Fire, Sierra Pacific Industries, Pacific Gas & Electric, local Native American tribes and the Butte County Fire Safe Council.
Derby represents Cal Fire in the group. During its meeting in October, he said, the Butte County Public Works Department presented the findings of a survey of dead and dying trees along a sample of county roads. The purpose was to provide a rough sketch of the problem and a cost estimate of cutting down and hauling off the trees that might fall across roadways.
Assuming it costs about $1,000 to remove one tree—that’s about average, Derby said—removing them all could run the county upward of $20 million, the survey estimates.
“We’ve already gotten to the point where there are more dead trees adjacent to our roadways than the county can pay to remove in a timely manner,” he said. “Even if [the estimation] is off by 50 percent, that’s still a lot. We don’t have that money.”
Cindi Dunsmoor, an emergency services officer for Butte County, also serves on the task force. In the coming months, she said, the county probably will follow the lead of 10 California counties (see info box) and apply for grant funding through the California Disaster Assistance Act. The grant would require a 25 percent match—still millions of dollars—so the county may enlist volunteers to mark the GPS coordinates of each tree that must be removed, she said. The volunteer hours would count toward the match, but the county would have to come up with the rest.
Additionally, the county must present a formal tree-removal plan to qualify for the funding, Dunsmoor said. “We need to show how we will remove trees that pose a danger to roads and buildings. … Butte County wants to be proactive in this. We have tree mortality issues we cannot ignore.”Free firewood
Private corporations are concerned as well. One is Sierra Pacific Industries, which owns 1.9 million acres of timberland in California and Washington and is one of the largest lumber producers in the U.S., according to its website.
In an email, spokesman Mark Pawlicki said the company has observed tree mortality related to bark beetles progressing steadily northward. Now, it’s affecting SPI’s forests around Stirling City and Feather Falls.
“We are seeing more dead trees than in the past,” he wrote, “and we have cut and removed about 35 percent more salvage from that area during the past two years than historically.”
Which leads to another problem: For decades, lumber companies took the bulk of their wood waste to biomass plants, which burn wood chips to make steam, turn turbine generators and produce energy. However, the plants have been closing, according to Chris Trott, a bioenergy consultant based in Tuolumne County.
Of about 60 biomass plants that were built in California in the late 1980s, only 20 are still operating, and nine have shut down in the past 2 1/2 years as PG&E has leaned more heavily on cheaper power from the federally subsidized solar industry, he said.
“The energy source for solar plants is free,” he said. “For a biomass plant, you have to go out and gather the waste wood, grind it up and transport it to the plant. About 60 percent of the cost of producing the power is getting the fuel source to the plant.
“Bottom line, energy prices are just too low to make biomass plants work.”
The trees still need to go somewhere. Gov. Brown’s emergency declaration in October 2015 directed the California Public Utilities Commission to extend the contracts of biomass plants that were set to expire, especially those in the southern and central Sierra Nevada. Six plants subsequently signed contracts, and together they have the capacity to process about 3 million tons of wood waste a year, Trott estimated.
Alternatively, sawmills might take the trees, but operations up and down the state already have a huge surplus. “Between the large-scale wildfires and this incredible tree mortality,” he said, “the sawmills have more than they can use.”
So Derby is discovering as he tries to find somewhere to truck the county’s snags. “The lumber mills are just glutted,” he said.
Beyond that, options are limited. Ponderosa pine doesn’t make good firewood; homeowners generally prefer hardwoods like oak or almond, Derby said. Wood from trees killed by bark beetles isn’t great lumber, either, because it’s discolored by the blue fungus that infects trees under attack.
“It’s not really any weaker—the properties of the wood haven’t been changed radically—but it doesn’t look nice,” Derby said. As a soft wood, ponderosa pine holds paint well and is often used in windows and siding. In other words, it’s valued for its appearance.
“Once it turns blue, no one really wants it,” he continued. “You can’t haul it very far before the cost of trucking exceeds the value of the logs on the truck. So, here I am going, ‘Can I use the value of these logs to offset the cost of cleaning up this mess?’”Reshaping the forests
Everyone who stands to be negatively affected by tree mortality is hoping for drought-busting rainfall, and the early returns are promising. According to the National Weather Service, the rainy season, which began Oct. 1, is off to its wettest start in the northern Sierra Nevada in 30 years.
And unlike the southern and central Sierra Nevada, some parts of the North State benefited from above-average precipitation last winter.
Even so, Webster isn’t encouraged by the long-term outlook. It would take multiple wet years to counteract the bark beetle epidemic, and even if it does rain a lot, forest density will still be a problem the next time California has a drought. His recommendation is thinning the forests by mechanical and chemical means, though on such a massive scale—particularly on public lands—that action is unlikely, he said.
“It’s sickening to me, for us to do nothing when we know what the solution is,” he said.
In Fettig’s opinion, the North State probably won’t suffer a mass tree die-off on the level of what’s happening to the south. “But, you know, we still have many susceptible stands on the landscape in Northern California.”
And, moving forward, climate change seems likely to favor the bark beetle.
“Climate change not only has an influence on tree vigor, it has important implications for the beetles themselves,” he said. “It affects their fitness, the timing of their events, and how many generations they can produce in a year.”
The drought might allow the western pine beetle to reproduce at a faster pace, though Fettig notes the species has “a flexible life history” and that the U.S. Forest Service needs to conduct more research on the subject. That’s an ominous possibility, considering that most climate scientists are projecting a warmer and drier West.
Indeed, if drought conditions become the new normal, Fettig said, disturbances such as bark beetle outbreaks and wildfires will increase in frequency and severity, ultimately reshaping California’s forests as well as the ecological goods and services and recreational opportunities people expect from them. For instance, if the ponderosa pine forests recede, they could be replaced by oak- or shrub-dominated systems.
And Fettig thinks we’ll find out sooner rather than later.
“I used to talk about these relationships in a more futuristic sense,” he said, “but I now argue these events are occurring, we’re witnessing them, and folks like me are measuring them and writing about them.”