The dense green forest that served as a scenic backdrop to Los Alamos is charred and blackened now, the once living trees transmogrified into scorched poles, the tangle of deadwood and brush that made up the cluttered understory reduced to a thick carpet of ash. It’s a skeleton forest, a disfigured landscape, a visible manifestation of death looming above the place that gave the world Fat Man and Little Boy.

That Los Alamos, of all places, should be hit by a firestorm is just one of a string of ironies generated by the Cerro Grande blaze, which burned 43,000 acres of northern New Mexico’s Jemez Mountains in May, forced 20,000 people to evacuate, did $1 billion in damage and took more than four weeks to extinguish.

Consider these twists:

• A deliberately set fire that if successful would have reduced the fire hazard to Los Alamos led to the destruction of more than 200 residences—and grew into the most destructive blaze in state history.

• The federal agency, the National Park Service, that had done the most to thin out the dangerously overgrown forest near Los Alamos started the chain of events that led to the disaster.

• Scientists at Los Alamos National Laboratory, so confident of their ability to control nuclear fire, were forced to flee in panic along with everyone else in the face of something as elemental as a forest fire.

• Although widely reported as a controlled burn run amok, the actual flames that got out of control in Los Alamos sprang from a risky backfire set by firefighters.

But perhaps the most profound irony of all, and one with frightening implications for the unnaturally thick forests of the American West, is this: In trying for the past 100 years to remove flames from the landscape through aggressive fire suppression efforts, federal fire managers have created infernos.

“We haven’t got rid of fire. We’ve merely changed the way fire interacts with the forest,” said James Agee, a fire ecologist with the University of Washington. Added Thomas Swetnam, director of the Laboratory of Tree-Ring Research at the University of Arizona, “There were frequent fires up to 1900 and then no fires for 100 years and now one fire comes through and the forest is toast.”

Toast is a good word for the seared forest behind Los Alamos. Over an eight-square-mile swath of canyons and ridges, virtually every tree has been killed. It looks like a bomb went off—with the exception that the trees are standing, not flattened. The fire burned so hot that air temperatures are estimated to have reached as high as 20,000 degrees Fahrenheit. In places the soil was vitrified, or turned to glass. When topsoil is cooked to that degree, it is sterilized: all the microorganisms that would normally help a forest recover from a fire have been killed. A forest burned to this extent is especially prone to a phenomenon called sheet erosion, where entire hillsides are washed away by rain. It is widely expected that when New Mexico’s annual monsoon season kicks in around the Fourth of July, there will be massive erosion in burned areas—and massive flooding through the numerous fingerlike canyons that cross the town of Los Alamos and the weapons laboratory and feed into the Rio Grande.

There have been numerous media reports about the fact that the lab has used those canyons as dumping grounds for decades—and that significant amounts of radioactive and chemical contaminants will almost certainly be carried this summer into the fabled waterway that is New Mexico’s lifeblood and that provides irrigation and drinking water to the bulk of the state’s population. Less attention has been paid to what extensive flooding and erosion might do to the burned forest west and north of Los Alamos in the Jemez range.

According to Swetnam, even if large amounts of topsoil are not washed away, it will in all likelihood take 100 to 200 years, and perhaps even longer, for the forest to come back—at least in the 14,500 acres that burned hottest. That’s how fragile the ecosystem is in the arid Southwest, where even healthy forest soils are unusually thin, requiring millennia to become established. If soil in the Cerro Grande burn area does wash off massively, “it might take thousands of years for these areas to come back as forest,” Swetnam said.

Anyone who finds that hard to believe should visit an almost-16,000-acre area immediately southwest of the laboratory that was burned in 1977. The La Mesa fire, as it was known, was only a third the size of the Cerro Grande blaze, and it did nowhere near the property damage. But like Cerro Grande, it was an out-of-control crown fire and it burned just as hot. The evidence for lasting damage can be seen today in the bleak, sparsely vegetated landscape that has replaced what before the fire was a thick, green forest. In the jargon of fire ecologists, an area that has been robbed of its tree cover is known as a “hole.” “There are still giant holes in La Mesa. And there’s no sign of anything coming back,” Swetnam said.

Reseeding efforts, which are already under way in the Cerro Grande burn area, could make a difference. But the La Mesa burn area was also reseeded—repeatedly—and it produced modest results, at best. Reseeding often doesn’t succeed in the Southwest because for the first few years after a blaze, the seeds, like the soil, get carried away by the torrential summer rains that hit the region after the spring fire season.

The implications of fires like La Mesa and Cerro Grande are profound. If a forest doesn’t come back after a fire, then it isn’t merely the landscape that has been changed, it’s the whole web of plant and animal life that took thousands, maybe millions, of years to evolve in that location. “You’re talking about converting a forest to a grassland or a shrubland,” Swetnam said. “If the kind of fires we’re getting today are not historical, if there’s no evidence they have occurred in recent centuries or millennia, then you’re changing ecosystems. That’s what’s beginning to happen out there.”

It’s because of the unnatural intensity of the Cerro Grande fire that one can make what would otherwise seem an absurd assertion: The blaze did more damage than the series of fires that scorched about 750,000 acres of Yellowstone National Park in the long, hot summer of 1988. More lasting damage, that is. Although significant portions of the acreage burned by Cerro Grande are not likely to recover quickly—and perhaps not at all—the land burned at Yellowstone twelve years ago has for the most part bounced back.

The forests torched by the Yellowstone fires were primarily made up of dense, almost impenetrable stands of lodgepole pine—and in lodgepole pine forests, crown fires are a normal part of the ecosystem. A sign that lodgepole evolved with crown fires is that the trees don’t drop many of their cones to the ground. Instead, the cones remain in the canopy—for decades in some cases—waiting for a crown fire to come along. When one does, the cones open up in response to the heat and, within days, seeds start to fall out. After a crown fire strikes lodgepole, the burned forest floor is carpeted with the seeds, and before long, lodgepole saplings have taken root.

A ponderosa pine forest is completely different. There, cones typically release their seeds upon reaching maturity. That strategy works well when the only fires that burned through were low-intensity ground fires. While those fires did to some extent destroy the seeds that were scattered on the ground, they didn’t destroy the source of the seeds—the trees themselves. But when a crown fire roars through a ponderosa forest—as happened in the Cerro Grande blaze—the seeds and the trees are killed, leaving no way for a new generation to establish itself. The forest is erased.

Though fire suppression—the legacy of Smokey Bear—is rightly blamed for the overstocked forests of the West, there is another, often overlooked factor that has also knocked nature out of balance: livestock grazing. In northern New Mexico, as in many other western areas 100 to 120 years ago, hordes of cattle and sheep brought by the railroads fanned out over the landscape. From roughly 1880 to 1920, wholly unregulated grazing by livestock denuded large areas. In places like eastern Oregon and Nevada, lush grasslands were replaced by sagebrush and fire-tolerant species such as cheatgrass. In northern New Mexico, the disappearance of grass meant that there was no way for ground fires to travel into ponderosa forests. Without fire to clear out the understory, virtually every ponderosa sapling that got established grew into a tree. As the twentieth century progressed, and as fire managers with agencies like the park service and the Forest Service stamped out every fire that popped up, these forests grew thicker and thicker. The densest stands, the ones packed with small, stunted, nutrient-starved trees, came to be called doghair thickets. In some areas of the Jemez Mountains, there are as many as 2,000 ponderosa pines per acre, compared to 25 to 80 trees per acre when fire was a frequent visitor to the landscape. “The basic story is that everything has gotten woodier,” said Craig Allen, a fire ecologist with the U.S. Geological Survey and a leading Southwest fire expert. “Meadows are filling in with trees, and forests that were once more open have become thicker and denser.”

While the timber industry often makes the claim that logging reduces the fire hazard, others say logging has exacerbated the situation by leaving behind flammable slash piles and by removing the biggest trees. Such trees have the greatest commercial value, but they are also the most resistant to fire.

Logging aside, no one disputes this: The forests of the West, particularly the ponderosa forests, which pose the greatest wildfire threat because of their inherent dryness, have lost their natural fireproofing. They have become explosive on a scale no one has seen before. “There’s a potential for 100,000-acre crown fires,” Allen said.

What’s to be done?

That question has taken on added urgency in the wake of the Cerro Grande fire—particularly for western communities that are just as much at risk from a forest fire as Los Alamos was. Santa Fe, forty miles southeast of Los Alamos, is one such place, as is Flagstaff, Arizona, located amid the largest ponderosa forest on the planet. Other towns that are standing directly in harm’s way include Missoula, Montana, which has seen its population swell with former city dwellers in recent years, and two Oregon communities, Bend, which has built into the extensive ponderosa forests on the east side of the Cascade Range, and Ashland, which like Santa Fe draws its drinking water from a municipally protected watershed that has become overgrown with trees.

An emergency measure sponsored by New Mexico Senator Jeff Bingaman following the Cerro Grande fire was working its way through Congress when Forest Magazine went to press. It would greatly increase, to $115 million from $65 million, the amount of money available to the government this year for efforts intended to prevent catastrophic wildfires.

The money would increase both prescribed burning and manual cutting and thinning of dense forest stands in the West.

Meanwhile, a moratorium on prescribed burning imposed by Interior Secretary Bruce Babbitt immediately after the Cerro Grande blaze got out of control has been partially lifted. Although the park service, which ignited the prescribed burn at Bandelier National Monument that eventually blew into Los Alamos, remains under the ban, all other federal agencies are now free to resume prescribed burns.

The fact remains, however, that the Cerro Grande fire has given prescribed burning a bad name—and has all but guaranteed that rural area residents will be more prone to protest whenever a prescribed burn is planned near their communities. Conservative western senators such as Idaho’s Larry Craig and New Mexico’s Pete Domenici have added fuel to the fire, so to speak, by questioning whether prescribed burning should continue at all in the wake of the Cerro Grande fire. Timber industry representatives, sensing an opportunity, have claimed that the fire is proof that burning is too risky and that increased logging is the best way to reduce the fire hazard.

Largely lost in the media frenzy over the Los Alamos disaster is the fact that prescribed burning has been carried out with remarkably few accidents. Since it began setting prescribed burns in the late 1960s, the National Park Service, for example, has set 3,746 burns covering almost 900,000 acres. The agency lost control of only 38—just 1 percent—of those burns. And only one other prescribed burn besides Cerro Grande has wreaked substantial property damage in recent years, a 1999 fire that burned twenty-three homes in a remote part of Northern California.

Still, anytime a fire is ignited, it is by definition a risky situation—a 16,000-acre prescribed burn conducted by the Santa Fe National Forest in 1993, for example, blew up unexpectedly one day and killed a firefighter. Such tragedies are likely to happen again. It is, of course, also possible that another Los Alamos could happen in the future. To what extent will people be willing to accept such mishaps?

Only time will tell. But the virtually unanimous consensus of fire scientists is that prescribed burning must not be abandoned. “Particularly with the drier forests of the West, fire is just too important,” said Agee of the University of Washington. “It’s essential to nutrient cycling, to creating good wildlife habitat, to maintaining the stability of the whole system.”

“The worst thing to do would be to stop burning altogether,” he continued. “Somehow, we have to increase the scale [of burning] and at the same time be more precise and cautious in its application.”

Even Wallace Covington, director of the Ecological Restoration Institute at Northern Arizona University in Flagstaff and a strong advocate of thinning, has said that the forests must also be burned—provided the burning follows extensive thinning to reduce the chances of a crown fire. “You need both [thinning and burning],” Covington said.

Agee said one possible approach would be to thin in areas that are close to towns and cities and to burn in areas that are more remote. And it is important, Agee said, to tailor a treatment to the needs of each site. “What you basically want to do with thinning and burning is mimic natural processes,” and those processes can vary even within a single mountain range, he said.

Swetnam from the University of Arizona said the Jemez Mountains, where the Cerro Grande fire burned, provides an example of such variation. While the midelevation ponderosa forests in the range did not evolve with crown fires, forests higher up in those mountains did.

No one is suggesting, however, that fire managers should start setting crown fires. The truth of the matter—however humbling it might be to accept—is that crown fires are impossible to control. What experts like Swetnam and Agee are saying, though, is that the federal fire managers directing burning and thinning efforts need to know their region in detail—or else they might have another Los Alamos on their hands.

In Swetnam’s mind, a lack of such knowledge was at the root of the Cerro Grande disaster.

It is not widely known—primarily because the media largely missed the story—that it was a backfire set by firefighters, not a prescribed burn, that swept into Los Alamos. Three of the investigators who took part in the government investigation of the blaze told Forest Magazine in late May that the prescribed fire that the park service set in a relatively high-elevation, moist area would have died out on its own had it been left to burn. They said the decision to treat the fire as a wildfire that needed to be extinguished—rather than merely a prescribed burn in need of guidance and monitoring—was a key error. That decision led fire managers in the field to undertake a risky maneuver, the ignition of a backfire in a much drier, lower-elevation area. The intent was to tie together two fire lines. But the result was that fire, carried by high winds, escaped into a nearby, thickly forested canyon. The rest is history.

“Once the prescribed fire was declared a wildfire, additional fire [was] introduced that ultimately produced the source of spotting and escape when high winds developed,” the investigators wrote in the report.

That a backfire was the immediate cause of the blaze led some observers to attack the basic conclusion of the government’s investigation that the Cerro Grande blaze was essentially a prescribed fire run amok. “It wasn’t the planned prescribed fire, but the unplanned, reactive emergency fire-suppression backfire that blew out of the project area,” said Tim Ingalsbee of the Western Fire Ecology Center in Eugene, Oregon. (Forest Magazine posted a news story on its Web site, www.forestmag.org, that raised substantial questions about whether the storm of controversy and criticism that was directed at prescribed burning in the weeks after the Cerro Grande fire was justified.)

To Swetnam, however, the critical error lay not in how the prescribed fire and the subsequent firefighting efforts were conducted, but in the decision to ignite the prescribed fire in the first place. The prescribed burn may very well have burned itself out if left alone, but that doesn’t change the fact that it took place in a very small, relatively moist area surrounded by a sea of tinder-dry, overstocked forest, Swetnam said. Neither does it change the fact that the burn was conducted following an abnormally dry winter and in the midst of a Southwest-wide drought that began in 1996.

“What was lacking was a recognition of what was going on in terms of larger time scales and larger landscape scales,” Swetnam said. “The fact of the matter is that there was a very high hazard for a bad fire year this year, and that understanding just didn’t filter down to the managers of a small national monument who were planning a burn.”

That message might have gotten through had anyone from the monument attended a conference for fire officials that was held in Tucson in February. The main topic of the meeting was the unusual fire hazard facing the Southwest in 2000. Swetnam said that although regional park service officials were there, no one from Bandelier who was involved in the Cerro Grande burn was present.

Swetnam mentioned something else that places the blame even more squarely on the shoulders of Bandelier fire officials. The Santa Fe National Forest, which borders Bandelier on three sides, issued a ban on prescribed burning roughly a week before the Cerro Grande burn was ignited. “They did the right thing,” Swetnam said.

In a larger sense, though, Bandelier officials aren’t really to blame. They were, after all, trying to deal with a mess that had been a long time in the making.

“Mistakes weren’t just made on May 4 [the day the prescribed burn was ignited],” Swetnam said. “They began a century ago. And they extend all the way up to the people in Los Alamos who built their houses up against that forest.”