Let Wildfires Burn: Study Shows Forests Bounce Back on Their Own

Modern fire management practices of logging and seeding interfere with an ecosystem's ability to restore itself, and does little to protect property.
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Photo by Gilitukha / iStock.

The May sun was still below the mountains when a small group of biologists set out in the brisk morning air of the Sierra Nevada. Comparing contour maps and checking radio channels, Dr. Chad Hanson and his team from the John Muir Project of Earth Island Institute spread out to explore the Stanislaus National Forest, about 160 miles east of San Francisco. The team was searching for black-backed woodpeckers, which are increasingly rare in the Sierra Nevada-Cascades region and which seek out forests that have recently burned with high intensity.

Many feared its intense heat would prove catastrophic to the forest and its soil.

The Stanislaus is one such forest.

In August 2013, the Rim Fire swept over the western slopes of the Sierra Nevada, burning 402 square miles. Many feared its intense heat would prove catastrophic to the forest and its soil, leaving behind an ashen, lifeless moonscape.

“I never really spent any time in a burned forest because I was raised to think it’s just a destroyed habitat,” shrugged senior biologist Kevin Kilpatrick. “I was amazed at how much life there is.”

As the biologists made their way through the charred remains and dense new growth, mountain quail began announcing their territories with clear, high notes sung from the leafy proliferations of young black oaks and waist-high lilac bushes. Ground squirrels chased each other across a fallen ponderosa pine, charred along its length.

After three years with good rain and snow, the forest floor was so crammed with wallflowers, lupines, paintbrush, rare Clarkia australis blooms, oak and conifer seedlings, and taller saplings, that it was a challenge to step through.

Like most wildfires, the Rim Fire burned at varying severities. A vast majority of the forest burned with low or moderate intensity, charring the understory and sparing most trees, or leaving 25 to 75 percent as standing dead “snags.” About one-fifth of the Rim Fire burned with high intensity, turning more than three-quarters of the trees into charred snags.

And yet, despite the perceived damage, research has shown that high-intensity fires quickly grow into some of the rarest and most biodiverse habitats in the Sierra Nevada.

Soon after the flames have subsided, a flurry of new events begins.

With the forest’s own nutrients back in the soil, a mosaic of fresh habitat opens up. Morels and other mushrooms emerge alongside seedlings. Up in the snags, beetles that have detected the smoke lay their eggs. Those eggs grow into wood-burrowing beetle larvae, high-protein food sources that draw woodpeckers. The following spring, hoards of other birds and animals appear amid wildflowers and the buzz of insects.

Backcountry wildfires have served as a powerful force of natural rejuvenation for eons.

Since 2014, Hanson, director of the John Muir Project, and his colleague Tonja Chi have led biologists into post-fire and unburned forests all across the Sierra Nevada. On that morning in May, the team spent hours walking and playing black-backed woodpecker sounds through high-performance callers at regular intervals; territorial woodpeckers fly in upon hearing the calls, and biologists try to follow the birds back to their nests.

Backcountry wildfires have served as a powerful force of natural rejuvenation for eons.

Old Forest Service records reveal that an average of 30 million to 40 million acres per year burned across the American West until the 1930s, when fire suppression efforts became more aggressive.

An American kestrel fledgling learns to fly with its parent. Both dwell in a post-fire forest that burned with high intensity during the Rim Fire. Photo by Maya Khosla.

Contrary to most expectations, the Rim Fire was far from catastrophic to plants and wildlife in the backcountry areas of Yosemite and the Stanislaus. By 2015, the deer and bears were back. Chi found a northern goshawk family in an area that had burned with low intensity. By 2016, bobcats were sighted and there was evidence that mountain lions had been drawn in by the bounty.

Recent research has revealed that rare California spotted owls forage in the high-intensity burn areas and nest in areas that burned with low intensity. Elsewhere, Hanson even found Pacific fishers in parts of Sequoia National Forest that burned in the 2002 McNally Fire.

Restoration ecologists working in post-fire areas of Yosemite National Park have recently documented hundreds of burned areas supporting rare plants and vibrant fungal growth. Vast swaths of charred trees that looked assuredly dead have bounced back to life surprisingly.

“If you just wait a little bit, the first spring after the fire, and for many springs after that, you see a complete transformation,” Hanson said. “These forests regenerate wonderfully on their own.”

It’s the subject of a growing body of new scientific study, and management practices are only just beginning to keep pace. Post-fire forests are typically managed with three major objectives in mind: public safety, economic offsetting, and wildland restoration. All three depend on federal funding; however, an increasing portion of federal funds are being used for fire suppression efforts in response to the extending annual fire season.

At present, massive salvage logging operations are standard follow-up procedure in national forests and other publicly owned lands. Logs are removed and herbicides are applied to give seeded conifers an edge over vigorous natural regeneration. If not valuable as timber, the logs are harvested to be burned in biomass plants, releasing carbon that would otherwise be stored or sequestered to fuel future growth.

“Logging is the worst thing you can do to these forests after wildfire.”

Logging in backcountry areas has been thought to protect distant communities from future fires while offering an opportunity to reimburse some of the costs of restoration. Such post-fire management methods are pursued primarily for economic reasons, and the results fall far short of achieving the objectives.

“Logging is the worst thing you can do to these forests after wildfire,” said Dominick DellaSala, chief scientist of the Geos Institute. “Seedlings are killed as the logs are dragged out, and natural regeneration processes are destroyed.” Mechanical deforestation methods tend to cause soil erosion, which hinders replanting efforts and requires two or three rounds of herbicide application followed by additional replanting.

New information compiled by groups including the Wild Nature Institute and the John Muir Project is paving a way for new fire-management methods.

“One of the really important things that we have learned in recent years scientifically is that we don’t have to make a choice between having post-fire habitat and protecting homes. We can actually have both,” Hanson said.

Having both means managing the vegetation around homes while letting the backcountry burn and regenerate naturally. This can have the added benefit of saving millions in taxpayer dollars every year, as the $15 million to $20 million in revenue gained from salvage logging pales in comparison to the $50 million to $100 million in cost, Hanson explained.

California spotted owl in a forest that burned with low intensity during the Rim Fire. Photo by Maya Khosla.

New management methods would essentially allow fire to burn in the backcountry and leave the forests to their own natural restoration processes. For public and homeowner safety, experts in the field recommend removals in the immediate vicinity of paved roads, utility lines, homes, and associated structures (100 feet of clearance is a common standard), but not in the backcountry. In high-traffic areas like Yosemite National Park, small woody plants are routinely removed in order to limit fires of high intensity.

“It makes no sense to clear-cut miles away from a community,” said Tim Ingalsbee, director of Firefighters United for Safety, Ethics and Ecology. “We just have to make homes more fire-resistant, and we know how to do that.”

“Species richness and diversity is going to go up even more as time goes on.”

Concerns that leaving piles of big fallen snags will fuel future fires have been largely disproven by recent studies. Wildfires are driven more by weather conditions—wind and hot temperatures—than by expanses with large snags. A 12-year study conducted by forest ecologist Sarah Hart and her colleagues found that high levels of large snags did not influence the rate a fire spreads.

About 70 percent of the snag forests created by the Rim Fire remain, 30 percent of the forests have been logged, and additional logging for biomass is currently underway.

Standing before the burnt Stanislaus, Hanson swept a great arc of post-fire forest with one hand.

“This entire area, for hundreds and hundreds of meters in every direction, all the way down to the private boundary, is an example of one of the areas that we’ve persuaded them to not log,” he said, calling for protection of the remaining forest and the species that depend on it. “Species richness and diversity is going to go up even more as time goes on.”

Within a week of their surveys, the team found two pairs of black-backed woodpeckers busy raising their boisterous young in high-intensity burn areas. Eight other woodpecker species were also thriving in the post-fire forests: the acorn, hairy, white-headed, pileated (the original “Woody Woodpecker”), Lewis’s, northern flickers, Williamson’s, and red-breasted sapsuckers. Bluebirds, nuthatches, and a host of other wildlife species that cannot build their own nesting cavities were seen making their living and raising their young in former woodpecker haunts.

Biologists have found over 80 other species of birds in the Rim Fire forests. The list, like the forest itself, will continue to grow if the habitat is left intact.