After 100 years of the Forest Service extinguishing the ground fires that would have burned every few decades through most ponderosa pine forests, some of those woodlands—among the most iconic of the West—contain many times more woody fuel than they would naturally. Above Colorado Springs, Fort Collins, and Boulder, forests that historically had fewer than 100 trees per acre now have upwards of 500. In Arizona some forests have 40 times their natural load of trees: an acre that historically had 20 ponderosas is now crowded with 800 to 1,200.4
Forests in Colorado’s Front Range have missed three, four, or five fire cycles that would have thinned them during the last century, Mike Battaglia, a young, slender researcher with the Forest Service’s Rocky Mountain Research Station, told me as we headed into the woods above Fort Collins, where he’s based.
“A forest, it’s like a lawn,” he said. “You have to cut your lawn every week.”
In the ponderosas, fires were effectively the forests’ lawn mowers, hedge clippers, and branch loppers. During the decades when the nation’s firefighters put out every wildfire, the government had effectively fired nature’s gardening crew.
Mike and I navigated through the jigsaw puzzle of public and private land that makes up Colorado’s Front Range. Old mining claims sprinkled throughout national forest land now hold homes. Mike slowed the green Forest Service pickup to point out widely spaced trees that showed where fuel treatments—timber cut from the woods by hand or burned away by controlled fires—had thinned the national forest. The spaces closed back up when we passed into private land, where a century of fire exclusion had allowed the woods to grow thick, and nothing was done to remove the accumulating timber.
The transition between the two areas exposed a counterintuitive reality. While the public looks at wildfires as a challenge for the federal government, the National Fire Information Center reports that between 1993 and 2012 only 22 percent of them burned on federal land. More than three-quarters of these fires occurred on state or private land.
At a development called Glacier View Meadows we passed huge houses in woods so dense we could barely glimpse them. Blackened trees from a recent fire lined the ridge. Few of the homeowners had cleared enough trees to create defensible space—an area that will keep flames in the forest from reaching the home.
“Those people are so lucky they didn’t burn,” Mike said. “That’s just ridiculous, how dense that is . . . It’s irresponsible.”
WHILE THE CANYONS ON COLORADO’S FRONT RANGE provide scenic and secluded homesites, some are more like slums of trees—overcrowded with evergreens struggling just to survive. But it isn’t just firefighting that has left them that way.
Virtually all of our land uses impact the “fire regime”—how frequently, intensively, and expansively a landscape burns. When ranchers filled the West with cattle and sheep, the animals grazed down the grasses that carried the mellow ground fires that had thinned many ponderosa forests. Miners tramped the land around their claims to bare soil, with much the same effect. With nothing left to carry fire on the forest floor, trees that would have burned when they were small instead survived and crowded in. As the forests grew denser and darker, they provided a more hospitable environment for Douglas firs, which normally prefer north-facing slopes that are cooler and moister, but in this case followed the shade provided by the thickening stands. Mountain mahogany, Gambel oak, and juniper, which ignite easily and burn fast, pushed in beneath the pines and firs. Eventually a forest that once had trunks spaced hundreds of feet apart was filled with trees standing shoulder to shoulder, all of them fighting to get enough sun, food, and water. Undergrowth, fallen needles and leaves, and dead wood gathered around their feet. Diseases and pests such as the mountain pine beetle spread through crowded forests like the plague. Dwarf mistletoe infested many boughs, causing witches’-brooms of dry bristles that burned like haystacks.
Without the ground fires to burn off low branches, the growing pines developed “ladder fuels”—limbs running from the ground to the crown like rungs that fires on the forest floor climb into the treetops. In the canopy, the flames find abundant, easily ignited needles and are less sheltered from the wind, which pushes them to lean and leap onto other trees. The fire that would have burned slow and low on the floor of a forest of widely spaced pines now rips through the crowded canopy as an “active crown fire.”
IN 1963 A. STARKER LEOPOLD oversaw a report on wildlife management for the National Park Service that called for reintroducing wildfire to federal woodlands. The son of naturalist Aldo Leopold, he grew up with conservation and wildfire. His father created the nation’s first wilderness area in the fiery Gila Mountains of New Mexico and then died of a heart attack while fighting a grass fire on his neighbor’s property in Wisconsin. Starker’s report urged the Park Service to allow natural fires that didn’t threaten development to run their course, and to set fires—prescribed burns—to thin the most overgrown forests. To many at the time, his ideas were the ravings of a madman.5
A quarter century later, when lightning fires that the Forest Service allowed to burn charred nearly a third of Yellowstone, politicians and the public responded with outrage. But by the time I was fighting fires, their benefit was clear. The forest ecosystems of Yellowstone were healthier a decade after the fires than they were a decade before them.
In 1995 the “Federal Wildland Fire Management Policy and Program Review” noted the need to put fire back on the land to correct what had become known as the “fire deficit” in the nation’s woodlands. “The task before us—reintroducing fire—is both urgent and enormous,” the report said. “Conditions on millions of acres of wildlands increase the probability of large, intense fires beyond any scale yet witnessed. These severe fires will in turn increase the risk to humans, to property, and to the land [with] which our social and economic well-being is so intimately intertwined.”6
But the reintroduction of fire hasn’t gone quite as planned. The excess timber and the warming and drying climate have made even carefully planned burns difficult to manage. And during the century in which the nation attempted to exclude fire from forests, they filled with homes.
AS PART OF THE GEORGE W. BUSH administration’s Healthy Forests Initiative, the Forest Service prepared an ambitious plan of “fuel treatments”—thinning forests with axes and chainsaws and burning them with controlled fire to bring them back to health.7
But many woodland residents resisted efforts to bring flames back into the forests. More fuel meant more smoke and other potential impacts on human health. Prescribed burns could so reduce air quality that Colorado allowed burning on only a handful of days with enough breeze to dissipate the smoke, in order to minimize health effects on nearby residents, but not windy enough to blow the fires out of control. Others worried about the impact of controlled fires on wildlife and recreational opportunities. And some just didn’t want flames in their forests.
In addition, the more desperately an overgrown forest needed fire, the more difficult a blaze set there would be to control. “We can’t just put fire on the ground in some of these landscapes because they’re too thick,” Mike Battaglia said.
Agencies and politicians representing the various stakeholders stepped in, and the permitting process for burns grew as thick and difficult to navigate as the forests they were intended to heal.
The woodlands that were most overgrown were often those closest to homes and communities, where past fires were most aggressively snuffed. But those are also, of course, where the greatest resistance to prescribed burns and thinning projects lay. So controlled fires were often set in remote forests where they did little to mitigate the threat to development but were easier for the public and policy makers to accept. Research by Tania Schoennagel, a research scientist with the University of Colorado’s geography department and Institute of Arctic and Alpine Research, showed that between 2004 and 2008 only 11 percent of federal efforts to cut down or burn away dangerously overabundant forest fuels occurred
in and around the wildland-urban interface, where homes abut fire-prone open space, despite government stipulations that significant resources to mitigate wildfires be focused on those areas.
Even projects that involve cutting down excess timber with chainsaws usually rely on a burn to remove the fuel. It’s costly, and sometimes impossible, to carry out the wood left behind, so foresters usually plan to burn away the wood they cut down. But weather, air quality, and public resistance often shut down those burns, leaving piles of firewood stacked in the forest.
Across Colorado there are at least 180,000 “slash piles” of timber from thinning operations, waiting for incineration. Some have sat there for decades. And a forest thinned with axes and chainsaws but still filled with this debris is like a medical patient who doesn’t finish a course of antibiotics—the treatment isn’t complete. You may have moved the hazard around rather than eliminated it.
“If you just remove the fuel from the canopy and put it on the ground, you might not have a crown fire, but you’ve increased the severity of the ground fire,” Mike said.
Many mountain residents view fuel treatments like surgery—a onetime fix. Prescribed burns, however, are more like medications for chronic illnesses that require regular dosage. If natural fires tend to burn a forest every 20 years, forest managers will need to introduce fire to the woods at roughly that interval to make up for wildfires they extinguish.
In the end, the treatment couldn’t keep pace with the disease.
According to a 2006 report from the inspector general of the U.S. Department of Agriculture, which oversees the Forest Service, at the rate the United States applies fuel treatments, it would take 90 years to bring forests prone to unnaturally severe fires back to health.8 To have any significant impact on fire risk, the Forest Service would need to treat 10 to 12 million acres a year, according to the 2005 “Quadrennial Fire and Fuel Review Report.” That’s nearly five times what the service currently treats.9
“Over the past 10 years we’ve consistently treated 2 to 3 million acres a year,” Elizabeth Reinhardt, assistant director of fire and aviation management for the Forest Service, told me when I asked her about the nation’s progress in healing sick forests. “. . . That’s a huge chunk of the landscape, and I think we are seeing some payoff from that now.”
That payoff, however, is small compared with the vast swaths of forests that need thinning. “When you look at [the] number of acres we burn every year and compare that to what we need to burn, it’s pitiful,” Mike told me.
In 2008 a statewide forest resource assessment showed that 6.8 million acres of Colorado’s forested lands were significantly less healthy than they had been historically due largely to excluding fires from those woodlands.10
MORE THAN A CENTURY AFTER the Big Blowup inspired America to try to extinguish every wildfire in the country, foresters were finding that many of the nation’s efforts to put fire back into the woods were just as misguided as that policy. Research published in 2012 by William Baker and Mark Williams at the University of Wyoming, who compared 100-year-old handwritten surveys from the U.S. General Land Office with data they gathered from trees along the lines the surveyors walked, showed that even in many ponderosa pine forests, dog-hair thickets (woods with a thick bristle of pines of the same age and size) and severe fires were more common than many foresters believed.11 In fact, Baker and Williams argued, in many western forests the megafires foresters and firefighters saw as unprecedented responses to overgrown woodlands weren’t out of keeping with historical fire regimes. Baker and Williams’s research led to heated arguments at fire science conferences and in the pages of academic journals and the popular press. About the only thing the various sides in the squabble agreed on was that the United States was not dealing well with wildfires and it was going to see a lot more land burning.
During the time of this debate I walked with Tom Veblen, a geography professor who studies forests and runs the University of Colorado’s Biogeography Lab, to look at the ponderosa pine forest at Heil Valley Ranch, outside Boulder. Tom had just completed a project with Rosemary Sherriff and a number of other researchers that showed, in Colorado’s Front Range, just 16 percent of the forests below about 9,000 feet, where ponderosas are the dominant species, had increased fire severity due to fires extinguished in the past leading to overly thick growth. Other forests had a history of large, intense fires even before the U.S. government started snuffing every wildfire.12
Sixteen percent is not an insignificant number, however, as Tom noted. And the areas showing an increase in wildfires over the past century are precisely where the most mountain homes have been built. The lesson of the new research by Sherriff and colleagues isn’t to stop thinning and burning the woods, but to focus those treatments where they will do the most good—overgrown ponderosa forests adjacent to homes and other development. Of course, those are the areas where resistance to such treatments is the greatest.
The remaining 84 percent of Colorado’s Front Range includes many other forest types—high country dominated by lodgepole pine, subalpine fir, and spruce forests, arid mesas of piñons and junipers, and even ponderosas mixed with other conifers higher in the mountains. In those forests increases in the size and severity of wildfires don’t correlate with an increased number of trees due to fires being extinguished. Most of the higher-elevation forests only burn every 100 to 300 years, so the nation’s century of fire suppression could only have interrupted their natural fire cycle once, if at all. Many of them always had big, intense wildfires.
WHILE THE DEBATE RAGED ABOUT which forests were seeing larger, more severe wildfires after too many fires were snuffed in the past, other scientists argued about whether wildfires were always a bad thing. Humans don’t want intense blazes near their homes, but other plants and animals depend on them.
Even the biggest and hottest fires leave pockets of slightly burnt or unburnt vegetation. Foresters refer to that pattern of lower- and higher-intensity burns as a “mosaic.” The right mix leads to a healthier forest with a variety of habitats for animals, more diverse vegetation, and a cleaner and more efficient watershed. In moderately burnt areas seedlings can grow faster than they would have if the fire had not come through at all, while areas cooked by high-intensity fires may not show green for years. The most intense fires destroy both the trees and their seed stock, and sometimes leave the soil “sterilized,” with few nutrients available to support new trees. But even bad burns are important parts of the mosaic.
“Snag forests”—remnants of severe fires in which only a few burnt trunks still stand—are a critical habitat for many species. Black-backed woodpeckers, for instance, are dependent on the charred trees in intensely burnt forests for their nests and the insects they eat.13 In the Northwest, reductions in the amount of severely burnt forests over the past century led to declines in the woodpecker’s population. According to Dick Hutto, who has conducted intensive research on the woodpecker and other birds that thrive only in severely burnt woodlands, that would imply that recent intensely burning wildfires aren’t as unnatural or unhealthy as many perceive them to be.
In the Southeast, longleaf pine forests that grew thick when fires were removed from the landscape a century ago showed similar reductions in bobwhite quail numbers. Hunters of the birds drove a movement to reintroduce fire in Florida and Georgia forests.
FOR MOST RESIDENTS OF COLORADO, human and otherwise, the greatest threat from wildfires isn’t the flames. The 2002 Hayman Fire scorched nearly 140,000 acres of the Upper South Platte watershed, which provides Denver’s million and a half residents with more than 75 percent of their water.
For two days in 2012, as wildfires once again overtook the state, scientists, land managers, and concerned citizens filled the city’s REI store to talk about the fire 10 years earlier that they were still recovering from. The parallels were impossible to miss.
“This year looks very similar to 2002,” Don Kennedy, an environmental scientist with Denv
er Water, said of the drought overtaking the state.
Runoff from the burn scars of the Hayman Fire and the 1996 Buffalo Creek Fire continued to fill the Strontia Springs Reservoir with ash, mud, cinders, and debris from the fire, Kennedy told the audience. “Engineers, when they built the reservoir, estimated that there would be 20,000 cubic yards of material per year,” he said. “We got 200,000 in one rain event.”
The sediment that washed down from the burn scars was heavy with cadmium, copper, and lead, which can poison the drinking water supply and are difficult to filter out. While the water showed somewhat higher concentrations of all three toxins, it was still below federal standards for drinking water. The sediment that slid into the water, however, had levels as much as 80 times higher. After other fires, dangerous levels of arsenic, mercury, zinc, and cyanide found their way into public water supplies. Denver Water spent $26 million digging toxic sludge from the Hayman Fire out of its reservoirs and managed to remove only about a quarter of the 625,000 cubic yards of fire-contaminated muck, forcing the utility to spend even more money treating the water.14
Denver Water realized that its money would be better spent preventing high-intensity wildfires in the first place. Between 2012 and 2015, it planned to spend $16.5 million to fund thinning projects and prescribed fires on 38,000 acres of land. One of those projects was in the Lower North Fork watershed, about 30 miles west of Denver.
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The Blackline
Conifer, Colorado—March 19, 2012
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