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Burning forests now means fewer mega-fires later. But who’s gonna light the match?


Burning forests now means fewer mega-fires later. But who’s gonna light the match?

One research team meticulously demonstrated the long-term benefits of low-intensity forest fires; while another documented the short-term political barriers.
November 22, 2023

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Despite the headlines about devastating wildfires scorching California, the state actually needs more forest fires. A lot more.

A century of aggressive suppression of wildfires has starved many western U.S. forests, including California’s, of the low-intensity fires that once shaped these forests thanks to lightning strikes and intentional fire starting by the region’s Indigenous inhabitants.

Now, new work by separate sets of researchers spells out both the potential benefits of more forest fires, and the barriers to making it happen.

The need for more fire on the landscape has been embraced in recent years by many forest ecologists and policymakers in the western U.S.  The U.S. Forest Service in 2022 announced plans to tackle the nations’ growing wildfire crisis by “treating” 200,000 square kilometers of forests—an area larger than the state of California. A state task force, meanwhile, has called for treating 2,0000 square kilometers per year of California forests. Such treatments frequently include a mixture of selective logging and prescribed fires.

Despite this newfound enthusiasm for some kinds of forest fires, evidence of the benefits has been confined chiefly to individual fires. So a team of scientists went looking for answers about whether the “right kind” of forest fires might squelch the apocalyptic mega-fires that have raged throughout California in recent years. Across the state, do low-intensity forest fires make it less likely that a intense fires will erupt there in later years?

The question poses a conundrum, because it’s asking whether a hypothetical different past (low intensity fire or no fire) would have led to a different future. Given their inability to inhabit alternate universes, the scientists tried to do something similar with 20 years of satellite data.


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The information, spanning 2000 to 2021, gave researchers a day-by-day, pixel-by-pixel view of where California forests burned, how intense the fires were, and myriad other climatic and environmental variables. The scientists matched pixels hit by low-intensity fires with similar pixels of forest that didn’t burn, creating what were essentially twin forests, one with fire and one without. Then the researchers watched what happened to them in later years.

The analysis revealed that in coniferous forests a low-intensity fire decreased the likelihood of a high-intensity fire occurring later by 64%, the scientists reported earlier this month in Science Advances.

Michael Wara, a co-author and researcher at Stanford University’s Woods Institute for the Environment, said he hopes the findings will spur policymakers to push for more use of fire in forests. “Beneficial fire is not without its own risks—but what our study shows is just how large and long-lasting the benefits are of this crucial risk reduction strategy,” he says.

A single fire, however, isn’t a permanent solution. The new research found the protective benefits of these less intense fires waned after six years, presumably as vegetation grew back and more dead wood built up, creating fuel for future fires. That means such fires—either prescribed ones set on purpose or wildfires allowed to burn—would need to become a regular feature of any forest for long-lasting benefits.

But while one group of scientists was touting the benefits of forest fires, another was warning that a more ambitious use of fire is being held back by a long list of barriers.  

“Prescribed fire is one of the most important tools we have for restoring natural fire regimes and undoing the effects of a century of fire suppression,” said John Williams, a scientist with the University of California Davis’s Department of Environmental Science and Policy. “But there are a number top-down barriers at the upper levels of management that keep us from growing the workforce and getting burns done at the scale and extent needed.”

In a new paper in Frontiers in Ecology and the Environment, Williams and other scientists at California and Oregon universities, as well as the state of California and the Nature Conservancy, warned that the use of prescribed fire is being held back by a longstanding culture of fire suppression within forest management agencies; a lack of adequate funding for prescribed burning; shortages in collaboration between agencies and with Indigenous groups; and a lack of encouragement for managers to start fires. “The incentive is often not to burn,” the researchers write. “Given that career risks and implementation challenges outweigh perceived benefits.”

As a consequence, prescribed fires burned just 370 square kilometers in California and 220 square kilometers in Oregon in 2019. That’s a far cry from the 80,000 square kilometers of California forest that scientists have said need treatments such as prescribed fire.

“There is a need for bolder leadership in support of prescribed fire,” Williams and his collaborators write, “even when it is politically uncomfortable.”

Wu, et. al. “Low-intensity fires mitigate the risk of high-intensity wildfires in California’s forests.” Science Advances. Nov. 10, 2023.

Williams, et. al. “Overcoming obstacles to prescribed fire in the North American Mediterranean climate zone.Frontiers in Ecology and the Environment. Nov. 6, 2023.

Image: ©Anthropocene Magazine (based on photo by © Pedro Turrini Neto |

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