As California grapples with more frequent catastrophic wildfires, the newly established UC ANR Fire Network plays an integral role in providing and advancing science-based solutions and delivering useful tools throughout the state. Recently, the Fire Network hosted an immersive field tour for California legislative staff in collaboration with Berkeley Forests to demonstrate their work in ongoing fire and forestry research. 

“We have such a rich network of fire experts and thought leaders within UC ANR,” said Lenya Quinn-Davidson, Fire Network director. “It was great to have everyone in one place, thinking about how we can best inspire and empower positive change through our research, education, outreach, policy and training.” 

During the Nov. 17 tour at Blodgett Forest Research Station, UC ANR staff and academics shared their research and experiences with a diverse group of legislative staff. The tour provided an opportunity for scientists and policymakers to connect over shared goals of addressing California's growing wildfire and forest management challenges. 

Legislative staff members included Rita Durgin, legislative aide for Assemblymember Cecilia Aguiar-Curry; Spencer Street, legislative director for Assemblymember Vince Fong; Byron Briones, legislative aide for Assemblymember Freddie Rodriguez; Emily Watson, legislative aide for Assemblymember Joe Patterson; Les Spahnn, legislative director for Senator Bill Dodd; Tammy Trinh, policy consultant for Senator John Laird; and Catherine Baxter, consultant for the Senate Natural Resources and Water Committee.

Sitting on 4,000 acres of Sierra forestland, Blodgett Forest Research Station is the flagship site for research within the Berkeley Forests network. The in-person visit gave attendees the opportunity to learn about the different forest management approaches practiced at Blodgett and understand the importance of maintaining research forests across the state. 

“We need research facilities like Blodgett,” Yana Valachovic, UC Cooperative Extension forestry advisor, told the group. “It's a way to ask these questions [about forest management].” The research questions answered through experiments at Blodgett have implications that reach beyond the station's boundary, which was demonstrated to tour guests over three tour stops.

UC Cooperative Extension forestry specialist and Berkeley Forests co-director Rob York led the four-hour tour, where visitors could view different forest management treatments and heavy equipment used for treatment, and learn firsthand about UC-led collaborative research projects. 

‘Can you run through it? Can you see through it?'

Tour guests joined York at the first stop, a stand (a group of trees of similar age and size) that has not seen treatment by humans for over 60 years. This first stop was a glimpse at what an unmanaged forest looks like through a forester's or wildfire scientist's eyes. Small trees, less than a few feet tall, clustered under a dense overstory, can facilitate a wildfire's quick movement from forest floor to tree canopy. Close clusters of trees make it much easier for fires to burn across a stand, and the spongy layer of duff underneath the guests' feet burns hot when conditions are dry. These stand conditions, coupled with an abundance of downed woody material, can lead to intense fire behavior when conditions are hot and dry. 

Leading California wildfire scientist and UC Berkeley professor Scott Stephens said, “Taking stands that look like this into the future with climate change…is nothing less than a trainwreck.” He and York emphasized that a forest's odds of persisting through wildfires are greatly increased when fuel loads are reduced and forests are thinned. York introduced his measure for healthy forest density, suggesting that guests ask themselves: “Can I run through it? Can I see through it?” the next time they visit a forest.

This is not to say that all fire is bad for a forest. Fire is a part of a healthy forest ecosystem and has been for thousands of years, thanks to natural ignitions from lightning and Indigenous stewardship and cultural practices.

The second stop on the tour was a stand where the overstory (canopy) had been thinned, but the surface fuels were not treated with prescribed fire. York explained that solely thinning a forest was not the answer, and that the best treatment would merge prescribed fire and overstory thinning treatments. In fact, a primary facet of the Fire Network's goals has been to increase the number and strength of community-based Prescribed Burn Associations (PBAs). Since 2017, 24 PBAs have formed throughout California and they greatly increase community capacity for prescribed fire in both forested and non-forested ecosystems.

Eating broccoli before dessert? 

The tour ended at a stand that had seen both thinning and prescribed fire treatments. It is part of an experiment comparing prescribed fire emissions to wildfire emissions. Another fuels management experiment happening at Blodgett studies livestock grazing as a tool to manage live fuel loads. This project is a collaborative effort between UCCE livestock advisor Dan Macon, Fire Network coordinator Katie Low, and other ANR advisors and specialists. The effort exemplifies the way wildfire demands attention and innovation from outside the fire and forestry fields.

Macon and Low are examining the efficacy of goat grazing and its implications for animal health  at Blodgett. This entails seeing how they can encourage goats to graze unfamiliar vegetation. Likening it to human behavior, Low asked the group, “If it was late at night, and you're craving a snack, which would you eat first: a bowl of steamed broccoli? Or your favorite dessert?” The goats that Macon and Low monitor clearly fill up on their “dessert” first and need extra encouragement to graze the woody vegetation, requiring more intervention on the herder's part. Through these glimpses into their research, Macon, Low and York demonstrated to the group that researchers are taking many approaches to help increase the state's wildfire resilience. 

Sitting at a critical point of both research and application, UC ANR staff were able to give visitors their unique perspective on the topics of climate change, prescribed burning and forest management on this tour. 

York, Stephens and Fire Network members maintained that California policy is moving in the right direction, but encouraged legislative staff to cease measuring impact through one lens. “It's not just about how many acres have been treated,” Stephens emphasized. “It's about impact. It's about changing the direction of the forest.” 

Wildfires burning in western U.S. forests have increased in size and severity since the late 20th century, with a number of recent fires exhibiting characteristics that match the criteria for mass fires – or fires that burn with high intensity over large continuous areas for long durations of time.

Operational fire behavior models, commonly used by federal and state fire suppression agencies to predict how wildfires will behave, cannot predict mass fire behavior, largely because they do not include the important combustion and fire-atmosphere interactions. The Creek Fire, which exhibited mass fire behavior when it burned through the southern Sierra Nevada in 2020, was analyzed to better understand the mechanisms and forest conditions that contribute to devastating wildfires.

Scott Stephens, Alexis Bernal and Brandon Collins in the Department of Environmental Science, Policy and Management at University of California, Berkeley, along with other colleagues used both ground-based and remotely sensed data to analyze behavior patterns of the 2020 Creek Fire to determine which variables were important in predicting fire severity. 

Findings indicated that dead biomass and live tree density were the two most important variables – more so than treatment history (i.e. timber harvesting, fire hazard reduction treatments, etc.), fire history or topography. Areas with the highest amounts of dead biomass and live tree densities were also positively related to high-severity fire patch size — indicating that large homogenous swaths of these types of conditions resulted in adverse, landscape-scale fire effects.

“Forest restoration must be increased greatly in California forests, the Creek Fire shows us what will happen if we don't move decisively ” said Stephens, lead author on the work, which is published in a new paper in the journal Forest Ecology and Management.

Additional analysis revealed that although the first two days of the Creek Fire were abnormally hot and dry, weather during the days of the greatest fire growth was largely within the normal range for the time of year (late summer).  The spatial distribution of fire intensity during those days, however, revealed some notable patterns, with the concentration of heat from the fire being in the opposite location of where it would be expected.  Specifically, on the day of the largest fire growth (Sept. 6), not only was the greatest heat concentrated away from the fire perimeter (or “flaming front,” which is the expected location for heat concentration), but a significant amount of heat was still being generated within the previous day's fire perimeter. This finding is critical to better understanding how traditional fire behavior models may or may not accurately predict fire behavior in forests that have large, contiguous areas of dead trees and high live tree density – an increasingly common forest fuel condition in Sierra Nevada forests.

The findings of this study have important implications for forest managers, as they indicate that in certain forest structures (i.e. those with large, homogenous swaths of dead biomass or high densities of live trees) conventional fire models may dramatically underpredict the spread rate and area burned because these models do not correctly capture the physics driving the fire.

The Creek Fire is one of a number of fires that shows how vulnerable forests are to current frequent-fire forest conditions, suffering high tree mortality and offering fuel conditions capable of generating mass fires from which future forest recovery is questionable because of type conversion and probable reoccurring high severity fire.

The study, titled “Mass Fire Behavior Created by Extensive Tree Mortality and High Density Not Predicted by Operational Fire Behavior Models in the Southern Sierra Nevada,” was published online on May 16 in the journal Forest Ecology and Management.

The authors of the paper are:

• Scott Stephens, Department of Environmental Science, Policy and Management, University of California, Berkeley.
• Alexis Bernal, Department of Environmental Science, Policy and Management, University of California, Berkeley.
• Brandon Collins, Department of Environmental Science, Policy and Management and Center for Fire Research and Outreach, University of California, Berkeley.
• Mark Finney, USDA Forest Service, Rocky Mountain Research Station.
• Chris Lautenberger, Reax Engineering.

Reposted from the UC Berkeley News

In his years managing California woodlands, Rob York has come up with a few quick and easy ways to gage whether a forest is prepared for wildfire. “The first question I like to ask is, ‘Can you run through the forest?'” York says.

York, an assistant cooperative extension specialist and adjunct associate professor of forestry at UC Berkeley, poses the question while standing in a grove of pine trees during a tour of Blodgett Forest Research Station, a 4,000-acre experimental forest in the northern Sierra Nevada. While fire suppression has allowed many of California's forests to grow thick and dense, this patch of forest is one you could actually run through: The area is punctuated by large trees spaced a few meters apart, separated by a smooth carpet of dried pine needles.

“The idea is, if it doesn't have a lot of buildup of surface fuel on the ground — sticks and logs — you should be able to run through it,” York adds. “Looking through this forest, I might have to jump over that log, but, generally, I could take a jog through it.”

For more than 50 years, York and other Berkeley forestry researchers have used Blodgett as a living laboratory to study how different land management treatments — including prescribed burning, restoration thinning and timber harvesting — can reduce the risk of severe wildfire and improve a forest's resilience to the impacts of climate change. In addition to research, Blodgett regularly hosts workshops to demonstrate different land management techniques to landowners.

After another year of record-breaking wildfires in California, the work at Blodgett is more critical than ever, and state and federal agencies are motivated to enact more effective forest management practices. In 2020, the state and the U.S. National Forest Service jointly committed to managing 1 million acres of California forests a year, and last month the Biden administration pledged billions in new federal funding to reduce wildfire risk in the state.

“[Blodgett] was really designed to eventually demonstrate land management alternatives and offer a glimpse into how they might look at bigger scales,” York said.

Experimenting with fire

Blodgett Forest is “pretty representative of millions of acres of Sierra mixed conifer forest,” said Ariel Roughton, a research stations manager at Berkeley Forests. After the majority of its trees were logged in the early 1900s, the forest was donated to Berkeley in the 1930s with the intent that it would be used to study sustainable timber production. Aside from a few old relics that survived early logging, the majority of the trees are regrowth and approximately 100 years old.

The forest is currently divided into a patchwork of tracts, each having received a different series of treatments since active management began in the 1950s and 1960s. And while fire suppression was once the policy at Blodgett — early fire ecologist Harold Biswell was even banned from using prescribed burns out of fear that they would interfere with the timber harvest — fire is now one of the primary tools that Blodgett researchers use to maintain biodiversity and reduce the risk of severe wildfire.

“Back then, people thought, ‘Why would you ever want to use fire for land management?' They wanted to grow trees, they want to grow timber. The idea of seeing black and char was literally off the scale,” said Scott Stephens, a professor of forest science and co-director of Berkeley Forests. “It's amazing that just a few decades ago, researchers didn't have the opportunity to do the work that Rob and Ariel and others are doing up here now.”

In the open, airy tract of forest that York could easily jog through, blackened scorch marks extend 10 to 15 feet up the trunk of each tree. Ecologists believe that before European colonization, these forests experienced fire once every 10 years or less, leading to open forest structures very similar to this one. Here, two years ago, Roughton, York and their colleagues conducted a prescribed burn to remove excess fuel from the ground and reduce the risk of wildfire.

“I think it's important to remember that nature hasn't taken its course without a lot of human intervention since the last glaciation, because there was strong Indigenous burning here,” said John Battles, a professor of forest ecology at Berkeley. “There has always been intense human stewardship of one sort or another.”

According to the researchers, it took 15 to 20 years of active management, followed by regular maintenance, to get the forest tract to this state. Over the years, they have worked to achieve the open forest structure by harvesting some of the bigger trees for timber, but leaving the largest behind. They have also used a machine called a masticator to chip up smaller trees and conducted regular prescribed burns.

While there are forest management strategies that can be effective on a shorter time scale, it usually takes at least a few separate treatments over the course of a few years to successfully restore a forest and reduce its wildfire risk, York explains.

“It can be a challenge to get to the forest structure that we want,” York says. “It takes a lot of time, and it takes a lot of investment.”

Climate change is also narrowing the annual windows of time when conditions are best for prescribed burning, limiting when and how often foresters can safely burn. Hot, dry conditions usually make prescribed burning too risky during the summer, while rain and snow in the winter can leave the forest too wet and damp for fire to burn. However, research at Blodgett is showing that, with the right management decisions, prescribed burning during the winter can be made more viable.

“Because of timber harvests that removed some of the canopy and subsequent treatments to remove the ladder fuel, we now have more light hitting the ground, and it dries out faster,” Roughton said. “We've gotten to the point out here where we're able to burn more easily because of our past management actions.”

Friends of the forest

While York likes to imagine running through the trees, Battles has a slightly different metric for evaluating the health of a forest.

“You need to be able to run through the woods,” Battles said. “But I also want to see all six of my friends as I do my run.”

Battles' friends are the six tree species that make up the Sierra mixed conifer forest: oak, ponderosa pine, sugar pine, white fir, Douglas fir and incense cedar. Fire suppression — and the dense, overgrown forest structures that can result — often favor the survival of some of these species over others, leading to forests that are dominated by just one or two species. This lack of biodiversity can make the forest, as a whole, less resilient to stressors like bark beetles or tree pathogens, which often target some of these species, but not others.

According to Battles, the open structure and frequent fire at this tract of Blodgett has allowed all six of his friends to flourish.

“I see my friend, ponderosa pine, which you don't see as frequently in the unburned forest because it's shade intolerant — it needs light. I see oak, and it also requires fire to get a lot of the oaks,” Battles said.  “I see all six of my friends all here, and you only see them when you have management like this.”

Over the past 20 years, research has shown that prescribed burning and mechanical thinning with tools like the masticator can also benefit soil quality and water availability, while having no significantly negative impacts on forest ecosystems. While burning or otherwise removing plants and trees can release carbon dioxide into the atmosphere, which accelerates the impacts of climate change, reducing the risk of severe wildfire can help maintain the whole forest for long-term carbon storage.

However, applying these techniques across 33 million acres of California forestland remains a monumental task. Prescribed burning requires a great deal of expertise and is also limited by weather conditions and air quality regulations. Meanwhile, mechanical tree thinning can be costly, and unlike timber harvesting, it does not generate any revenue for landowners — though Berkeley researchers have suggested that creating a market for small trees and other woody biomass could help offset the cost while limiting carbon emissions.

“Fire used to be so common in this system, and that's no different than in most forests in California. But, when you take it out for that long, you begin this transformation,” Stephens said. “That's why we have to get both public and private entities together to come up with a philosophy to be able to move forward on this. Blodgett is 4,000 acres — that's interesting, but it doesn't really address the needs of the state. We always hope that our work shows people what's possible and then enables them to continue it.”

In his years managing California woodlands, Rob York has come up with a few quick and easy ways to gauge whether a forest is prepared for wildfire.

“The first question I like to ask is, ‘Can you run through the forest?'” York says.

York, an assistant cooperative extension specialist and adjunct associate professor of forestry at UC Berkeley, poses the question while standing in a grove of pine trees during a tour of Blodgett Forest Research Station, a 4,000-acre experimental forest in the northern Sierra Nevada. While fire suppression has allowed many of California's forests to grow thick and dense, this patch of forest is one you could actually run through: The area is punctuated by large trees spaced a few meters apart, separated by a smooth carpet of dried pine needles.

“The idea is, if it doesn't have a lot of buildup of surface fuel on the ground — sticks and logs — you should be able to run through it,” York adds. “Looking through this forest, I might have to jump over that log, but, generally, I could take a jog through it.”

For more than 50 years, York and other Berkeley forestry researchers have used Blodgett as a living laboratory to study how different land management treatments — including prescribed burning, restoration thinning and timber harvesting — can reduce the risk of severe wildfire and improve a forest's resilience to the impacts of climate change. In addition to research, Blodgett regularly hosts workshops to demonstrate different land management techniques to landowners.

After another year of record-breaking wildfires in California, the work at Blodgett is more critical than ever, and state and federal agencies are motivated to enact more effective forest management practices. In 2020, the state and the U.S. National Forest Service jointly committed to managing 1 million acres of California forests a year, and last month the Biden administration pledged billions in new federal funding to reduce wildfire risk in the state.

“[Blodgett] was really designed to eventually demonstrate land management alternatives and offer a glimpse into how they might look at bigger scales,” York said.

Experimenting with fire

Blodgett Forest is “pretty representative of millions of acres of Sierra mixed conifer forest,” said Ariel Roughton, a research stations manager at Berkeley Forests. After the majority of its trees were logged in the early 1900s, the forest was donated to Berkeley in the 1930s with the intent that it would be used to study sustainable timber production. Aside from a few old relics that survived early logging, the majority of the trees are regrowth and approximately 100 years old.

The forest is currently divided into a patchwork of tracts, each having received a different series of treatments since active management began in the 1950s and 1960s. And while fire suppression was once the policy at Blodgett — early fire ecologist Harold Biswell was even banned from using prescribed burns out of fear that they would interfere with the timber harvest — fire is now one of the primary tools that Blodgett researchers use to maintain biodiversity and reduce the risk of severe wildfire.

“Back then, people thought, ‘Why would you ever want to use fire for land management?' They wanted to grow trees, they want to grow timber. The idea of seeing black and char was literally off the scale,” said Scott Stephens, a professor of forest science and co-director of Berkeley Forests. “It's amazing that just a few decades ago, researchers didn't have the opportunity to do the work that Rob and Ariel and others are doing up here now.”

In the open, airy tract of forest that York could easily jog through, blackened scorch marks extend 10 to 15 feet up the trunk of each tree. Ecologists believe that before European colonization, these forests experienced fire once every 10 years or less, leading to open forest structures very similar to this one. Here, two years ago, Roughton, York and their colleagues conducted a prescribed burn to remove excess fuel from the ground and reduce the risk of wildfire.

“I think it's important to remember that nature hasn't taken its course without a lot of human intervention since the last glaciation, because there was strong Indigenous burning here,” said John Battles, a professor of forest ecology at Berkeley. “There has always been intense human stewardship of one sort or another.”

According to the researchers, it took 15 to 20 years of active management, followed by regular maintenance, to get the forest tract to this state. Over the years, they have worked to achieve the open forest structure by harvesting some of the bigger trees for timber, but leaving the largest behind. They have also used a machine called a masticator to chip up smaller trees and conducted regular prescribed burns.

While there are forest management strategies that can be effective on a shorter time scale, it usually takes at least a few separate treatments over the course of a few years to successfully restore a forest and reduce its wildfire risk, York explains.

“It can be a challenge to get to the forest structure that we want,” York says. “It takes a lot of time, and it takes a lot of investment.”

Climate change is also narrowing the annual windows of time when conditions are best for prescribed burning, limiting when and how often foresters can safely burn. Hot, dry conditions usually make prescribed burning too risky during the summer, while rain and snow in the winter can leave the forest too wet and damp for fire to burn. However, research at Blodgett is showing that, with the right management decisions, prescribed burning during the winter can be made more viable.

“Because of timber harvests that removed some of the canopy and subsequent treatments to remove the ladder fuel, we now have more light hitting the ground, and it dries out faster,” Roughton said. “We've gotten to the point out here where we're able to burn more easily because of our past management actions.”

Friends of the forest

While York likes to imagine running through the trees, Battles has a slightly different metric for evaluating the health of a forest.

“You need to be able to run through the woods,” Battles said. “But I also want to see all six of my friends as I do my run.”

Battles' friends are the six tree species that make up the Sierra mixed conifer forest: oak, ponderosa pine, sugar pine, white fir, Douglas fir and incense cedar. Fire suppression — and the dense, overgrown forest structures that can result — often favor the survival of some of these species over others, leading to forests that are dominated by just one or two species. This lack of biodiversity can make the forest, as a whole, less resilient to stressors like bark beetles or tree pathogens, which often target some of these species, but not others.

According to Battles, the open structure and frequent fire at this tract of Blodgett has allowed all six of his friends to flourish.

“I see my friend, ponderosa pine, which you don't see as frequently in the unburned forest because it's shade intolerant — it needs light. I see oak, and it also requires fire to get a lot of the oaks,” Battles said.  “I see all six of my friends all here, and you only see them when you have management like this.”

Over the past 20 years, research has shown that prescribed burning and mechanical thinning with tools like the masticator can also benefit soil quality and water availability, while having no significantly negative impacts on forest ecosystems. While burning or otherwise removing plants and trees can release carbon dioxide into the atmosphere, which accelerates the impacts of climate change, reducing the risk of severe wildfire can help maintain the whole forest for long-term carbon storage.

However, applying these techniques across 33 million acres of California forestland remains a monumental task. Prescribed burning requires a great deal of expertise and is also limited by weather conditions and air quality regulations. Meanwhile, mechanical tree thinning can be costly, and unlike timber harvesting, it does not generate any revenue for landowners — though Berkeley researchers have suggested that creating a market for small trees and other woody biomass could help offset the cost while limiting carbon emissions.

“Fire used to be so common in this system, and that's no different than in most forests in California. But, when you take it out for that long, you begin this transformation,” Stephens said. “That's why we have to get both public and private entities together to come up with a philosophy to be able to move forward on this. Blodgett is 4,000 acres — that's interesting, but it doesn't really address the needs of the state. We always hope that our work shows people what's possible and then enables them to continue it.”