Fire and smoke in a forest

Where There’s Smoke…

For years, CNR researchers have been studying fire, its causes and its repercussions. Now, in the wake of last fall's wildfires, their work has become more important than ever.

Changing the Trajectory of Land Management

The recent epidemic of catastrophic wildfires across California could be the beginning of a new normal, warned a paper by College of Natural Resources fire scientists published in Bioscience in January. Tens of thousands of acres of deadened trees—victims of drought and insects like the bark beetle—stand ready to ignite during the next dry season. And conditions will only worsen in the next 5 to 10 years as the trees fall to the ground, threatening more urban areas and watersheds. 

Among land management agencies and researchers, two schools of thought have emerged: One advocates focusing on already-dead trees as the next target of wildfires. But the other side, represented in the recent study, argues for replacing triage with more proactive measures to make live forests more resilient. It suggests removing small-to-moderate-sized trees by mechanically thinning forests and setting more prescribed fires.

“While the majority of green California forests are extremely vulnerable to fire, drought, and bark beetle attack, there’s still time to act,” said Scott Stephens, professor of fire science in the Department of Environmental Science, Policy, and Management (ESPM) and co-author of the study. “The next 10 to 20 years will be critical—we must change the trajectory of our land management before fire and bark beetles do it for us.”

In recent years, Stephens and his colleague Bill Stewart, an ESPM Cooperative Extension specialist in forestry, had already been interacting with state lawmakers frequently, hosting them at UC’s Blodgett Forest Research Station and testifying at legislative hearings. Since the fall’s disastrous wildfires, they have held several meetings with California legislators’ senior staff to discuss specific ideas for reforming fire and forest management, especially near highly populated areas.

“It would be a valuable step forward for California to emphasize policy development and energize prescribed-fire programs from both operational and legal perspectives,” Stephens said. 

PHOTO: Tom Bruns

Fungi and Forest Recovery

Tom Bruns, a professor in the Department of Plant and Microbial Biology, is currently conducting research focusing on saprobic fungi that colonize soil after a wildfire. Using genomics, his lab is trying to understand what saprobes—which feed on dead material—do in postfire environments, with the long-term goal of using this data to facilitate postfire recovery and carbon storage.

According to Bruns, forest fires often leave behind areas of soil that repel water, owing to waxes in natural plant litter that congeal in cooked soil. “Recovery crews are interested in these hydrophobic soils because they lead to eroding hillsides,” he said. “If we understand the microbes involved in degradation of postfire hydrophobic compounds and learn to facilitate their activities, we may be able to reduce the risk of erosion.”

Using Light to Predict Fire Behavior

Public forest managers have long used behavior modeling to predict severe fire areas and take preventive measures like tree thinning and prescribed burns. In California, such modeling has been particularly challenging, because the state’s forests are so complex and diverse in their topography, composition, volume, and quality. So local researchers have been employing new technologies and approaches to fire behavior modeling. 

A lidar image of a forest

A Sierra Nevada forest, captured using LiDAR technology. 

PHOTO: Marek Jakubowski

In December 2017, CNR researchers reported in the open-access journal Remote Sensing on new technologies and approaches that may be effective for fire behavior modeling. Co-authored by Maggi Kelly, Stefania Di Tommaso, Danny Fry, Brandon Collins, and Scott Stephens, among others, the article specifically focuses on the potential of LiDAR—light detection and ranging—technology.

“It’s an active sensor that sends light pulses, usually from an aircraft, to penetrate the forest canopy,” said Collins, a research scientist at Berkeley’s Center for Fire Research and Outreach who also works with the U.S. Forest Service. “The time it takes for those pulses to hit something in the forest and bounce back to the sensor has been related to the height of the vegetation that they’re hitting. From a fire standpoint, it’s describing the arrangement and the quantity of potential fuel. This allows us to better target our management to reduce hazardous fuel conditions, which ultimately improves our chances at minimizing impacts from future wildfires.”

On the Front Lines of Firefighter Health and Safety

Research has shown that firefighters experience higher rates of many cancers, owing to their greater exposure to hazardous materials. In 2013, Rachel Morello-Frosch—a professor in ESPM and the School of Public Health—became the principal investigator of the Women Firefighters Biomonitoring Collaborative Study. 


A partnership of six science, advocacy, and firefighting-safety organizations, the study is the first to focus specifically on female firefighters and their exposures to carcinogens that could lead to breast cancer. Morello-Frosch’s team has been analyzing chemical measurements taken from blood samples provided by female members of the San Francisco Fire Department and comparing chemical levels with those in samples provided by female office workers. 

Then came the October wildfires that ravaged Sonoma, Napa, and Mendocino Counties. Since many Bay Area municipal fire departments provided mutual aid during the wildfires, Morello-Frosch and her collaborators saw an opportunity to collect unique exposure data from both male and female firefighters on the scene. 

“Because our study of women firefighters was already up and running, we were able to amend our protocols to collect blood samples from firefighters who went to help with those wildfires,” said Morello-Frosch. The researchers also collected samples from firefighters who did not serve at those sites, to conduct a comparative analysis of chemical levels in the two groups. 

“The last few fire seasons have taught us that it’s not a matter of if another of these wildfire events will happen but when,” said Morello-Frosch. “Now we’ll be even better prepared, with protocols in place before the next fire season so we can get out in the field and do sample collection more quickly. As researchers, we must also be rapid responders, ready to collect critical data that can help firefighters protect themselves from hazardous chemical exposures.”