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.’”