Making sense of the mountain pine beetle infestation.
By Patrick Doyle | Photographs by Matthew Staver
Entomologist Bob Cain is wandering through a lodgepole pine forest looking for mountain pine beetles just east of Loveland Ski Resort. He’s been hunting for 30 minutes with little luck. Many of the trees are already dead, the beetles long gone. Our timing, Cain says, is off. The bark beetles tore through this part of Colorado last year and the Forest Service has already cut down many of the infected trees for firewood. Still, Cain, who’s the Forest Service’s Rocky Mountain Regional Entomologist—aka the resident bug expert—remains optimistic. There have to be some bark beetles still hanging out, he says, because some of the larger trees in the area are still alive.
With a gray beard and a lanky build, Cain looks like a slightly less hirsute Jim Henson. “Oh!” he shouts, pointing to a lodgepole pine tree about 10 yards away; its needles are still green. “This looks promising.”
The trunk is pockmarked with spots of pale-yellow resin where the tree attempted to pitch out the digging beetles. Cain crouches, pushing away the detritus from the forest floor. “Look at the frass at the bottom of the tree—it’s the sawdust from their digging,” he says.
Cain stands, unsheathes his hatchet, and hacks at the bark a few inches above a resinous pitch tube. The bark comes off in chunks. It’s incredibly dry. Underneath he finds a dead beetle and the paths, or galleries, where its larvae have chewed through the tree’s sugary phloem. The wood is stained a grayish blue from a fungus that the beetle carries in its mouth. The deadly fungus blocks the tree from transporting water up to its branches.
Cain looks up at the lodgepole’s canopy. “This tree is still green,” he says, shaking his head, and scans the disappearing forest. “But it’s going to die.”
In a little less than 10 years, the diminutive mountain pine beetle—a tiny black insect the size of a match-head—has destroyed 41 million acres of high-altitude lodgepole pine forest in North America, cutting a wide brown swath across the Rocky Mountains from New Mexico to British Columbia. Within the next five years, nearly every mature lodgepole pine is expected to die in Colorado and Wyoming, as are a majority of lodgepoles in British Columbia, Idaho, and Montana. Scientists are calling it the worst insect attack in North American history.
Mountain pine beetles are native to the continent, and as old as the trees they attack. Along with fire, they’re part of the forest’s cycle of renewal. The species prefers lodgepole pines, but are also known to infest ponderosa and white pines; other species of bark beetles attack other coniferous trees. Outbreaks have occurred routinely since western settlement. In the 1980s, Yellowstone and Glacier National Park were hit hard, and Colorado forests suffered infestations in the 1930s and 1950s. Those outbreaks, though, were confined to small, isolated forests, and trailed off.
“What’s different now is that all areas are outbreaking at the same time—they’re all connected,” says Barbara Bentz, a Research Entomologist and Project Leader of the Forest Service’s western bark beetle research group. “Temperatures have warmed and the droughts have impacted the trees, which are weakened.” The epidemic resulted from the combination of rising temperatures, years of western drought associated with climate change, and the advancing age of our lodgepole forests.
Forest age is one of the biggest problems. Many of our forests regenerated after the clear-cut logging of the early days of settlement, meaning they’re a grandfatherly 80-plus years old, boasting wide trunks loaded with sugar that’s ripe for beetle munching. Counterintuitively, decades of fire prevention have actually made the problem worse. Many of the trees that are now dying may have, or should have, burned long ago. “We’ve been fighting fires for over 50 years now,” says Tim Ebata, Forest Health Initiatives Officer with the British Columbia Forest Practices branch. “Since we started suppressing fires, the stands have continued to grow into a susceptible age for the beetles.”
Elderly pine trees have only two natural defenses against the beetles: cold temperatures and water. A few days of -40 degrees in the winter kills large quantities of beetles, as does a cold snap of -20 degrees in the fall or the spring. Unfortunately, the coldest days of winter have been on the decline as climate change ramps up. Freezing Wyoming winters once killed 80 percent of bark beetle larvae, but only eradicate about 10 percent now. Mountain temperatures have risen by about one degree each decade over the past 30 years—a small change, but enough to throw the ecosystem out of whack. Winters have gotten so mild, in fact, that beetles are now attacking pines above 10,000 feet, their traditional altitude barrier. And as more trees die and decay, they’ll be releasing more carbon back into the environment—enough, according to a report in the journal Nature, to convert “the forest from a small net carbon sink to a large net carbon source.”
The second defense is water. Well-hydrated trees run thick with sap that can actually push an invading beetle right out of the bark and help seal the hole. A decade of western drought has only made the trees more susceptible. Big, densely packed trees are forced to compete for limited quantities of water. Once the trees are parched, they are unable to produce enough resin to cast the beetles out. Drought, according to a recent study in Science, has weakened trees enough that even young trees are susceptible to an infestation. The result? Larger and larger broods of bark beetles finding plenty to eat everywhere they go—a nearly biblical plague.
From the top of Colorado’s Berthoud Pass it’s possible to look out over Grand County, one of Colorado’s finest recreation areas, loaded with alpine skiing, cross-country skiing, mountain biking, trail running, fly-fishing, and high country vistas. But it’s hard to get past the stands of thousands of dead lodgepole pines. Grand County was the epicenter of the bark beetle outbreak, but now it’s the beetle-kill equivalent of scorched earth. Nearly every mature lodgepole tree has been killed, impacting everything from recreation to home values.
The standing dead trees first turn brown, a phenomenon locals refer to as rusting; a couple years later, they drop their needles and fade to a dull gray. Although it’s a natural process, it’s not very pretty, especially in lands treasured for their views. But such standing dead forests are more than just blights—the dead trees are at a high risk of blowing over in the wind. Loggers call them widowmakers. The Forest Service has had to close several dozen campgrounds across Colorado and Wyoming over the past few summers to clear trees that it feared would kill campers. Ski resorts, particularly in Colorado’s Summit and Grand Counties, meanwhile, have been clearing and spraying trees to try to preserve tree skiing and protect visitors.
Real estate has taken a hit, as new buyers have proven reluctant to purchase homes in and around the devastated forests. “One of the first things that people say to me when they come up here is, ‘Oh! All the trees,” says Cliff Anderson, Owner of Real Estate of Winter Park, who’s been selling homes in Grand County for 24 years. Anderson says he’s never seen the market so bad, and although teasing out the impacts of the beetle from the recession is difficult, he’s sure it hurt business in the second-home community. “It’s definitely having an impact,” he says. “I’ve had buyers who just can’t handle it aesthetically—they say they can’t buy a place here because they love trees.”
Folks who already own land and expected to live amidst the forests—or at least, with views of the forests—have been left reeling, forced to watch their trees die or pony up for treatment. Traditional pesticides, as well as newer treatments like pheromone packets, which trick beetles into thinking a tree has already been attacked, are somewhat effective but they need to be applied to individual trees. That’s an expensive prospect, considering that treatment costs about $10 a tree and needs to be applied annually.
Accustomed to managing our landscapes, the natural reaction to the epidemic is to ask what the hell we’re supposed to do about it. The answer unfortunately is not much. The trees are going to die. And we can’t log ourselves out of that fact. It’s our heavy-handed management of the forests—combined with our fossil-fuel-based lifestyles—that got us into the mess. Logging all the dead timber isn’t realistic either, since building roads up the rugged mountainsides would be cost-prohibitive, not to mention incredibly damaging to the already-weakened landscape and the tourism-based economy. “The epidemic is kind of like a fire moving up a hill,” says Bentz. “It’s really difficult to stop.”
Since we can’t keep the trees from dying—and can’t clear all of them—the forest floor is going to be loaded with fuel. In 2006, then U.S. Senator Ken Salazar (who’s now the Secretary of the Interior) warned that Colorado and other states faced a potential “Katrina of the West.” Cal Wettstein, the Forest Service’s Incident Commander of the bark beetle management team in Colorado and Wyoming, predicts a Yellowstone-level fire down the road. “It’s inevitable,” says Wettstein. “There will be a big fire.”
With that threat in our future, the federal and state governments have spent millions of dollars trying to create a defensible space, or firebreak, at the wild-urban interface. “We’re trying to be strategic and focused on our fuel treatment,” says Wettstein. “We’re creating defensible spaces to stop fires before it gets near communities or water supplies.”
But now, the biggest threat is another parching drought—at this altitude, even dead trees won’t burn without hot weather and heavy winds. Drought, of course, is one of the reasons that all these trees are so weak in the first place. And drought is tied to climate change, which weakens trees and increases the beetle population. Since we can’t quickly fix climate change, the beetle epidemic won’t end until they run out of weakened trees. And all we can really do about it is hope that it gets cold and wet.
In the meantime, nascent businesses are trying to take advantage of all the dead trees. In British Columbia, the government has been subsidizing logging, while in Colorado, a group of businessmen started up the Colorado Beetle Kill Trade Association, which includes members creating wood pellets for pellet-burning stoves, a small mill, and a group of craftsman creating furniture and home products from the beetle-killed, blue-stained wood. Full Circle Design, a furniture store in Breckenridge, has even dedicated a corner of its store to the blue-wood products; U.S. Congressman Jared Polis recently bought a swanky blue-wood coffee table.
“We have all this wood,” says Rich Dziomba, owner of Blue Knight Group, a newly created bark beetle consulting firm, who wants state and federal governments to subsidize use of the beetle wood for siding, fencing, and biomass energy. “We need to create a market for it—we need to be buying this stuff.” Realistically, though, that market is limited, since wood for lumber needs to be harvested quickly, and large biomass plants need a solid 20 years of material to make their investment worthwhile. “It’s going to be a very short window to use those trees,” says Wettstein. “But once these dead trees are gone, we’ll return to a smaller, more sustainable forest.”
After traipsing through the woods by Loveland ski area for another half hour, Cain suggests a trip to Empire, Colorado, to see an area that the beetles plowed through several years ago. It’s only a 20-minute drive, but the devastation is stunning. Many of the trees have already lost their needles, and the remainder sport dead, red needles.
Despite the loss, Cain happily wanders through the woods, pointing to signs of new growth. “Lodgepole is a pioneer species,” he says. “It comes in after a disturbance. There’s plenty of seed source here, and seedlings are already getting established.”
Cain sees the beetles as just another succession in the forest. In the short term, the tree canopy won’t hold as much snow, meaning that streams, rivers, and lakes will see increased water runoff. In the long term, the forest will regenerate and become host to more aspens and firs—and yes, even lodgepoles.
Most of us won’t see a mature lodgepole forest again in our lifetimes—it will take 70 to 80 years for the trees to return to their current state. But in landscape terms, what we’re witnessing is a long-awaited renewal. “It’s difficult for people to understand that this ecosystem is on a different time scale than we’re on,” says Wettstein. “It’s an unprecedented event in our lifetimes, but it may have happened in the millennia before us. It’s tough to change perspective.”
The biggest unknown is how climate change will affect the renewed forest. If the weather is warmer and wetter, then vigorous, sap-heavy trees will be able to fight off beetles, but if it’s warmer and dryer, then younger and younger trees will succumb to first drought, then the tiny jaws of beetles. Mountainous forests aren’t disappearing, though, they’re just changing.
“We’re not worried about having trees on these sites,” says Cain, gesturing to the forest around him. “We may have areas that change in types of trees, to aspens or firs, but we’re going to have trees. The forest is resilient.”
From the Winter 2009/2010 issue.