Hiking through a sliver of the endless, rolling forest that blankets California's San Bernardino Mountains, Bernhard Voelkelt points out the fire-inviting pathology that surrounds us. "This is an overcrowded stand of trees," he says. "There's no space for sunlight to get to the ground. It hasn't burned here in 50 or 60 years, maybe 100." Without sunlight, these smaller trees die and become kindling. "They have to be taken out from under these mature ones," Voelkelt says.
A sort of Teutonic intellectual mountain man who lives in Lake Arrowhead, one of the many towns and tiny villages that dot the mountains, Voelkelt started off promoting renewable energy but over time his focus widened to include an obsession with the growing risk of wildfire in the region. Now he devotes his life to nudging and helping communities and government agencies do whatever it takes to keep fires from springing up and wreaking havoc. In some cases, he is paid reasonably well, such as when he consults for state and local agencies. But much of the time he isn't paid at all, because few communities have put aside money for this sort of thing.
Roaming the winding roads that snake between and through the various canyon-top communities in a battered GMC Suburban, Voelkelt can't seem to make it 800 yards before spotting some affront to fire safety that inspires him to lurch to the side of the road and stalk off for a closer look.
"These trees are turning red – that's the bark beetle. They'll die and rot and become fuel," he says. "These grasses will ignite instantly, and then the fire will load up on the dead vegetation on the ground here; then it'll ignite the dead branches low on the tree trunks, and the tree will go up like a Roman candle, showering the area with embers. You'd have a canopy fire here, with the fire jumping fast from treetop to treetop, temperatures reaching a thousand degrees. . . ." He starts to look as if he might himself spontaneously combust.
The heart of the problem is that we have become a victim of our remarkable success at fighting wildfires. Nature intended for forests to burn. Dense, unbroken, unburned forest, such as the one that Voelkelt is decrying, is largely a modern invention. Many Native American tribes regularly put torches to forests and vegetation wherever they lived – mostly to make it easier to hunt, gather, and settle, but also because the land thrives when it periodically burns. Fire, when it comes frequently enough, tends to pass relatively lightly through the wildlands, clearing out choking undergrowth and returning nutrients to the soil while leaving larger trees mostly unharmed. Such fires tend to die out fairly quickly, too, simply because there's less to burn.
Just how profoundly forests change when fire is taken out of them for long periods of time was revealed in a study released last year by the Forest Service, based on work in the Stanislaus National Forest, east of San Francisco. "When you have a forest that used to burn every six years or so, and then you keep fire out for a century," says Knapp, "you get more and more biomass that burns more and more intensely when it finally does go." The study found that tree stands are well over twice as dense today as they were in the 1920s. Perhaps even worse, much of the extra biomass has taken the form of fallen branches and wood dust piled deep on the forest floor – the sort of stuff a hiker would eagerly gather as kindling for a campfire. "Any fire is going to burn more intensely, over a larger area," Knapp says. "You're going to lose an entire landscape in an afternoon."
Studies comparing California forests with similar areas in Mexico that haven't experienced a century of fire suppression confirm that fires in the Mexican forests tend to be much smaller and less intense. While differences in climate and vegetation between the two regions complicate the comparison, the differences are stark. Voelkelt estimates that the milder Mexican fires typically leave three-fourths of the larger, older trees in good shape, resulting in a healthier forest – whereas fires in the American West often destroy 90 percent of those trees. Adds Knapp, "The science has clearly pointed out that we need to have more good fires to prevent bad ones."
You don't have to burn all that much of the forest – just patches that can serve as firebreaks. Prescribed burns, as the technique is called, aren't as dangerous as one might think. The risk can be minimized by doing it when and where there are moist, windless conditions amenable to smaller, slower fires, and to have plenty of people and crew on hand that can prepare firebreaks ahead of time and tamp out any flames that get out of the intended burn area. The Obama administration, the Forest Service, and virtually everyone in wildland management is all for prescribed burns. After all, as Knapp notes, our forests are going to burn one way or another; it's practically lunacy to wait for them to do it as raging killers rather than as neatly managed pussycats.
But there is at least one drawback to the approach: Once in a great while, a prescribed burn slips away. That's rare – out of more than 16,000 prescribed burns recorded in 2012, only 14 escaped. One killed three people and destroyed 27 homes in Jefferson County, Colorado. It does little good to tell someone who has lost a loved one or a home that the fire would have happened on its own. All that person knows is that the government set a fire that ruined his or her life. It's an image pro-logging conservative politicians get a lot of mileage out of in the western states – which stand to gain the most from prescribed burns.
Forest thinning – cutting down and removing excess small trees and underbrush from an overloaded wildland area – is a far less risky form of prevention. But it's expensive, and no one has come up with a good scheme for disposing of the biomass that gets cut down. And many experts doubt that thinning is worth the effort given the magnitude of the threat.