Burn, Learn, Repeat

In California’s Sierra Nevada, UC Berkeley researchers are turning decades of fire research into action.

November 18, 2025
By Andrew Chapman
A young woman with her back to the camera, wearing fire protective gear and looking at a prescribed fire

Undergraduate student Cosette Monson “holding” prescribed burn at Whitaker’s Forest in October 2024. Photo by Leigh Ambrose.

In late summer of 2022, the Mosquito Fire was burning hot and bearing down on UC Berkeley’s Blodgett Forest Research Station in the Sierra Nevada.

Rob York and his colleagues had spent a decade treating Blodgett’s main tract with prescribed burns to mitigate fire risk. Although York was concerned about the fire burning the research infrastructure, he felt confident their treatments would work.

“I was worried about the buildings and my office, but I was never worried about the forest,” says York, who is an associate professor of Cooperative Extension in the Department of Environmental Science, Policy, and Management (ESPM) focused on forestry and pyrosilviculture. Sure enough, when the blaze hit areas that had been treated, the intensity dropped, and firefighters were able to contain it.

This is one story of a catastrophe quelled by strategic forest management, with many others unfolding across California. As wildfires have intensified statewide, so too have efforts to study how to mitigate wildfire while also using fire as a tool. Now, many Berkeley researchers are collaborating directly with policymakers and forest managers to bridge the gap between the laboratory and the landscape.

Intentional fire

The need for a refined wildfire playbook has never been greater. Megafires are increasingly common in California due to climate change and more than a century of fire suppression as the dominant forest management approach, which allowed fuels to accumulate and forests to grow dangerously flammable.

The result? Thousands of destroyed structures, tens of thousands of premature deaths from smoke within the last two decades, millions of tons of carbon dioxide released into the atmosphere, and vast stretches of California’s natural beauty up in smoke. For mountain communities in the Sierra Nevada, effective fire management isn’t just about smoke drifting into the city—it’s about protecting both lives and livelihoods.

For decades, Berkeley faculty have been at the forefront of research that has shifted prevailing attitudes away from prioritizing fire suppression to understanding that the problem is not too much fire, but too little—it’s the type of fire we are getting that’s the problem. As far back as the 1950s, Professor Harold Biswell conducted the first experiments using prescribed burning to lower the risk and lessen the severity of wildfire in California; this approach flew in the face of conventional wisdom and laid the groundwork for subsequent Berkeley research into how prescribed and natural fires can benefit forests, rangelands, and ecosystems.

Now, forest managers have several proven tools to reduce the intensity of wildfires. Mechanical thinning using chainsaws and heavy machinery removes smaller trees and brush that fuel these fires. Targeted grazing by livestock also reduces grasses and shrubs. During fires, firefighters even seek out grazed areas to stageequipment since the grazed land is less likely to burn.

The most effective tool in the manager’s kit, however, is prescribed burning. Setting intentional fires during lower-risk conditions reduces the woody surface fuels that can lift flames into the forest canopy or crown. Kristen Shive, an assistant professor of Cooperative Extension in ESPM, says the proven effectiveness of prescribed burns has already saved many acres of forests from destruction.

But York says that it’s become harder to conduct prescribed burns during conventional “burn windows”— the specific period of time when environmental conditions are suitable for conducting controlled fires safely and effectively—because the climate is changing and permitting has become very cautious about allowing practitioners to burn. Burning during wetter and cooler times is challenging because a dense canopy and thick layer of woody debris on the forest floor retain moisture in the forest, which is thus less flammable. This leaves the forest even more vulnerable under extreme wildfire conditions, such as particularly dry or windy periods.

“We can flip that around,” York says. “We actually want to increase the flammability so that we can burn during those cooler and wetter days when the weather is more moderate.” Through his research, York has found that less dense forests with a higher proportion of pine trees are more compatible with prescribed fire during these periods of moderate weather, which often occur in the middle of winter. Ponderosa pines are especially beneficial because they are fire-resistant, but their needles dry out quickly, providing excellent surface fuel that helps prescribed fire spread safely across a treatment area. York says that forest managers can selectively keep pine trees when treating forests and can replant pines after wildfires.

Reforestation projects create new challenges, however. More forests are being replanted through state-funded reforestation grants, but after a few years, these young forest stands create new risks because fires can more easily reach their crowns. When young forests burn, 100 percent mortality is common.

A man and a dog in an outdoor setting with a map

Rob York briefing staff before a controlled burn at UC Berkeley’s Whitaker’s Forest in 2024. Photo courtesy of Rob York.

Two people in orange coats and hard hats with drip torches starting a prescribed fire.

Student crews conduct a prescribed fire at a Berkeley Forests research station. Photo courtesy of Rob York.

“We have to be more aggressive at lowering surface fuels in these forests,” York says. In the past, researchers assumed it was too dangerous to do prescribed burns in young forests. York changed that. Through testing, he showed that burns can be successful if timed carefully, such as in the middle of winter. York says you have to accept losing some trees along with the brush, “but 20 percent tree mortality is a lot better than 100 percent.”

In addition to refining the features of successful prescribed burns, York conducts workshops that empower private landowners to perform their own burns. The impact could be huge: half of California is privately owned land.

“Once landowners and community members participate in a prescribed burn, they learn that it is doable and that fire isn’t something to fear,” York says. “You can take care of your land in a pretty cost-effective way, if you know the basics of it.”

A map showing various levels of burned areas in a forest

A map of the Redwood Mountain Grove in Kings Canyon and Sequoia National Parks, which burned in the 2021 KNP Complex Fire. Subsequent prescribed burning in the blue unburned area— which is surrounded by areas that did burn (shown in grey, tan, and yellow)— could be less risky as the surface fuels around it were already consumed. Map courtesy of Kristen Shive.

Wildfires can work for us

While prescribed fire is becoming more accepted, the practice remains expensive and is too logistically complicated to treat every California forest.

But Shive has found surprising opportunities for forest treatments that work in tandem with wildfires. Her research shows that substantial areas of even overall unwanted wildfires have areas that burned at lower severity, where the mature trees survived. In these areas, the conditions may even be improved after the wildfire as though a prescribed burn had occurred. “We can take lemons and make some lemonade,” she says.

In a recent study, Shive demonstrated that across the Sierra Nevada, wildfire resulted in some beneficial effects in over half of all burned areas, even during the massive 2020 and 2021 fire seasons, which saw some of the most destructive fires in California history. “From the forest perspective, these severe fires can be devastating. For example, in the iconic giant sequoia range, we tragically lost roughly 18 percent of all large, mature sequoias in those two fire years alone,” Shive says. But she adds that the majority of the burning was “good, lower-severity fire in giant sequoia groves that, frankly, we were probably not going to get to with prescribed fire.”

“When doing treatments in an unburned forest that’s dense and loaded with fuel, one treatment is never enough,” Shive notes. “What the wildfire did was take the first pass.”

Recent fires in an area can also facilitate prescribed fire and wildfire management by creating fuel breaks, allowing managers to contain fire more easily within previously burned areas and reducing the risk of a prescribed fire escaping control lines.

Shive’s research demonstrates that in fact, wildfires burn more acres of forest at a lower intensity—achieving the same goals as a prescribed burn—than they burn at such a high severity that the forest can’t recover. She says these lower-severity burn areas showcase that there are silver linings to even these unwanted wildfires, providing opportunities for follow-up treatments that can enhance forest resilience in places that might otherwise have remained untreated for decades.

Through her extension work, Shive delivers talks and prepares research briefs that keep forest managers informed about the latest scientific developments. “Part of my role is to be a science communicator,” she says, adding that forest managers often bring research questions to her from their experiences in the field, inspiring new research and creating a cycle that results in better forest management.

A crisis requires coordination

The scale of California’s wildfires has demanded a coordinated response. In 2018, the governor’s office launched the California Wildfire and Forest Resilience Task Force to align state, federal, and local organizations that inform wildfire policies and actions. As co-chair of the task force’s science advisory panel, forest ecologist and ESPM Professor John Battles keeps the task force informed about the latest and most important science on wildfire mitigation.

Two people in yellow jackets and hard hats walking into a forest with ashes all over the forest floor

Fire resource advisors scout a sequoia grove to assess the impacts of the 2024 Coffee Pot Fire. This grove experienced a predominantly low-severity fire that paved the way for follow-up forest management treatments. Photo courtesy of Kristen Shive.

Battles argues that one of the task force’s biggest successes has been integrating scattered data on metrics like forest treatments, wildfire hazard, drought vulnerability, wildlife habitat, and water resources from different agencies, university labs, and private entities into accessible, shared platforms.

Through the task force, Battles also provides scientific guidance to Planscape, an open-source tool developed in collaboration with Google.org, the California Natural Resources Agency, the US Forest Service, and the geospatial analysis consulting firm Spatial Informatics Group. This free tool provides decision support to local governments and organizations seeking to make informed improvements to their forest management and wildfire procedures by integrating state and federal data and presenting it in an accessible way.

Unlike other decision support systems that require specialized training, Planscape—while sophisticated—has a well-designed map interface and is simple to use. It is built for local fire safe councils and community groups—the people who know their landscapes best and have a long-term stake in protecting them.

The state is now providing grants for communities to organize their own treatments to help prevent catastrophic wildfires. Sustained community buy-in is essential to long-term success, Battles says. “You’re not going to fix it and go away,” he adds, “Every year you’re going to do a million or a million and a half acres of treatment, and then you have to come back in 10-15 years and do it again.”

Even while acknowledging the enormous challenges ahead, researchers express cautious optimism about changing attitudes toward fire and forest management. “I’ve seen a huge increase in awareness and public acceptance of prescribed fire,” Shive observes.

Despite political uncertainties and the scale of the problem, Battles also sees genuine progress in the collaborative approach that brings together federal and state agencies, rural communities, and academic researchers. From his eight years co-leading the science advisory panel, Battles believes that the only sustainable solutions are ones that local communities embrace.

Through this community-centered approach and new science-backed techniques, California is taking incremental steps toward using more beneficial fire on the landscape. “We’re making progress,“ Battles says. “We haven’t solved it yet, but we’ve seen big changes.”

This story originally appeared in the Fall 2025 issue of Breakthroughs magazine. Read the full issue on our magazine page.