BUCK MEADOWS, Calif. — With long strides, Chad T. Hanson plunged into a burned-out forest, his boots kicking up powdery ash. Blackened, lifeless trees stretched toward an azure sky.
Dr. Hanson, an ecologist, could not have been more delighted. “Any day out here is a happy day for me, because this is where the wildlife is,” he said with a grin.
On cue, a pair of birds appeared, swooping through the air and alighting on dead trees to attack them like jackhammers. They were black-backed woodpeckers, adapted by millions of years of evolution to live in burned-out forests. They were hunting grubs to feed their chicks.
The black-backed woodpecker is one of the rarest birds in California, and lately it has become something more: a symbol of a huge scientific and political debate over the future of fire in American forests.
Scientists at the cutting edge of ecological research, Dr. Hanson among them, argue that the century-old American practice of suppressing wildfires has been nothing less than a calamity. They are calling for a new approach that basically involves letting backcountry fires burn across millions of acres.
In principle, the federal government accepted a version of this argument years ago, but in practice, fires are still routinely stamped out across much of the country. To the biologists, that has imperiled the plants and animals — hundreds of them, it turns out — that prefer to live in recently burned forests.
Human lives are at stake, too. Firefighters die, more than a dozen in some years, putting out fires that many scientists think should be allowed to burn. Conversely, a shift toward letting more fires rage is certain to raise fears about public safety in communities bordering forests.
Scientists contend that if money were redirected from firefighting into projects like fireproofing homes, those communities could actually be made safer. But the politics of the shift would be difficult, at best.
Climate change complicates the picture. It is making wildfires more likely, essentially punching through the human effort to suppress fires. That may, in the short term, help achieve the scientific goal of having more fire on the landscape. But longer term, it could lead to profound changes in forests, potentially driving some creatures to extinction.
The question coming into focus is simple, but answering it in the age of global warming will be a lifetime challenge for a rising generation of forest managers: How much fire is enough?
A History of Fires
Scientists are still trying to figure out how regularly forests burned in what is now the United States in the centuries before European settlement, but reams of evidence suggest the acreage that burned was more than is allowed to burn today — possibly 20 million or 30 million acres in a typical year. Today, closer to four million or five million acres burn every year.
Scientists say that returning forests to a more natural condition would require allowing 10 million or 15 million acres to burn every year, at least.
“From an ecological standpoint, everything I’ve learned teaches me this is a good idea: Stop putting out fires,” said Jennifer R. Marlon, a geographer at Yale who was among the first to use the term “fire deficit” to describe the situation. “These forests are made to have fire.”
Yet in the few years when wildfires actually burn close to 10 million acres, that is seen as a national emergency, producing panicky news coverage portraying fires as devastating to forests. This year may turn out to be one of the more prominent recent years for fire; more than five million acres have already burned, temperatures are at record highs in parts of the country, and there are weeks of fire weather still to go.
Efforts to suppress fires began in the 19th century, largely motivated by the view that forests should be seen as standing timber with economic value. By the 1930s, industrial-scale techniques allowed firefighting agencies, including the United States Forest Service, to suppress fires across the landscape.
A handful of scientists began arguing decades ago that this was a mistake. Over the past decade or so, the research has crystallized into a new understanding of the role of fire in forests.
Hundreds of species can live in recently burned forest, researchers have learned, and many of them prefer these charred forests above any other habitat. Some beetles even have heat-sensing organs to detect forest fires from miles away, rushing toward them to lay their eggs in the just-burned trees.
Far from being calamities, fires are now seen by many experts as essential to improving the long-term health of the forests, thinning them and creating greater variability on the landscape.
Yet that awareness has yet to penetrate the public consciousness.
People still think forest fires are bad and expect the government to try to stamp them out, even in remote wilderness areas. Federal and state firefighting costs in some years approach $2 billion.
Arguments for a new approach have yielded change in some parts of the country, such as the northern Rocky Mountains. But in California and many other areas, firefighters still try to extinguish virtually every blaze.
The battle over forest management may come to a climax in the next few years, though — and the tiny black-backed woodpecker could be one reason.
New Life Among the Ashes
In two visits with a reporter to the Sierra Nevada, in 2016 and 2017, Dr. Hanson made the case that letting more of the woods burn is essential to restoring the ecological health of forests.
Only a few years after the great conflagration known as the Rim Fire burned more than 250,000 acres of California forest near Yosemite National Park, Dr. Hanson cited signs of rejuvenation even in the most severely burned areas.
On several hikes, mostly in Stanislaus National Forest, which sustained most of the damage from the Rim Fire, he pointed to newly sprouted trees carpeting the forest floor. Butterflies flitted through lush stands of shrubs. The once-dense forest had taken on a parklike openness, essential for certain kinds of plants to thrive.
Still, the dead, leafless trees, standing 80 to 100 feet tall and glistening black in the sun, made for a sight both starkly beautiful and disconcerting.
Any standing dead tree is called a snag, and Dr. Hanson calls any burned forest where the trees have been left alone a snag forest. His group, the John Muir Project of the Earth Island Institute in Berkeley, Calif., has pressed the argument over the past decade that snag forests are among the most important plant and animal habitats in North America.
Dr. Hanson has made himself a thorn in the side of state and federal agencies, pestering and sometimes suing them. But gradually, they have begun to acknowledge that burned forests must be viewed as special places.
Still, considerable disagreement remains among scientists about exactly how forests should be managed. Dr. Hanson studied under Malcolm North, a Forest Service scientist who also holds a position at the University of California, Davis — but the two men have come to disagree. Dr. North argues that Dr. Hanson goes too far in arguing that even the most severe fires, those that produce some large patches of snag forest, are a good thing.
“I would agree it’s actually a valuable habitat type,” Dr. North said. “It’s just that he’s arguing for way too much of it, and in really big patches.”
In cooperation with another group, the Center for Biological Diversity, Dr. Hanson’s group in 2012 filed a petition to list the black-backed woodpecker as threatened under the Endangered Species Act. They argued that fewer than 1,000 breeding pairs might be left across Oregon and California.
Under the Obama administration, biologists at the United States Fish and Wildlife Service declared that protection for the bird might be warranted, but it is unclear what the Trump administration will do with the proposal. It faces a Sept. 30 deadline. If the petition is turned down, the environmental groups are likely to sue.
A listing for black-backed woodpeckers would almost certainly require a new approach to forest fires that would include allowing some fires caused by lightning to burn. The lucrative, and scientifically controversial, practice of logging trees just after a fire might well be banned across large areas, since those dead trees turn out to be important habitat for many types of creatures, including the woodpeckers.
Scientists who want to let more fires burn take pains to make clear that they do not mean to put people’s lives on the line. In fact, they believe the government could make people safer than they are today if it redirected funds into community fire-safety projects.
They also point out that many people are putting themselves at risk by building homes in remote, fire-prone areas without taking essential steps to make the homes fire-resistant, like installing metal roofs. Extensive research shows that wildfires will usually leave properly built and maintained homes with little damage, but rural communities have hesitated to adopt strict building codes.
“People like to do whatever they damn well please on their own land,” said Timothy Ingalsbee, a former firefighter who now runs an advocacy group, Firefighters United for Safety, Ethics and Ecology. “But when a wildfire comes, they’re calling Uncle Sam saying, ‘Please, come save me.’”
The argument for more fires will be especially difficult in California, the most populous state in the nation at 39 million people. Air quality is already poor across large parts of the state, and fires burning many miles away can produce smoke and haze that aggravate asthma and annoy people, potentially creating a political backlash.
Randy Moore, head of the Forest Service district that covers California, said in an interview that the agency was taking the recent scientific work seriously. In a milestone, it is drafting plans for three national forests in California that may call for allowing fires caused by lightning strikes to burn in some remote areas.
“We need to move toward fire as being not necessarily an enemy,” Mr. Moore said.
Dr. Ingalsbee believes another force is going to drive change in the nation’s fire policies, perhaps more so than any argument over woodpeckers. The families of wilderness firefighters who died on the job once tended to accept their lot resignedly, but some are starting to sue, asking why the government is defying the latest science in a risky attempt to extinguish remote fires.
“The lives of young people are not worth saving trees that really need to burn anyway,” Dr. Ingalsbee said. “Families are no longer going to be mollified by politicians showing up at the memorial talking about their fallen heroes.”