“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.
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.”
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.”
A study led by ecologists at UC Berkeley has found significant flaws in the research used to challenge the U.S. Forest Service plan to restore Sierra Nevada forests to less dense, and less fire-prone, environments.
An example of a mixed-conifer forest in the Sierra de San Pedro Martir National Forest, Baja California Norte, Mexico. This forest experienced active, natural fires until the 1970s. (Photo by Carrie Levine).
Until recently, the consensus among forest ecologists was that before European settlers arrived in the Sierra, the forests were mostly open conifer forests dominated by big trees and low-to-moderately severe fires every eight to 12 years. The Forest Service recently released a plan to restore the range's forests back to this state following decades of fire suppression and timber harvesting regulations, which have created dense, fire-prone forests.
But recent studies, using a newly developed methodology, have argued that the Sierra Nevada was actually a more dense forest than the consensus view. These new studies were used to back a lawsuit to stop the agency's plan to restore Sierra forests following the 2013 Rim Fire. The Berkeley study refutes the conclusions of these studies and identifies flaws in their methods.
“We went through the data and showed that, in every case, this method estimated that the density of trees was two to three times higher than was the reality,” said Carrie Levine, a Ph.D. student of forest ecology at Berkeley and lead author of the study.
The study was recently published online in the journal Ecological Applications. Berkeley professors John Battles and Scott Stephens and research scientist Brandon Collins were co-authors on the publication. Also involved in the study were researchers from Harvard Forest, the USDA Forest Service Pacific Southwest Research Station, the University of Montana, Utah State University, University of California, Davis, and the USDA Forest Service Pacific Southwest Region.
An example of a densified mixed-conifer forest in the Plumas National Forest in Northern California. Fires have been suppressed in this forest for more than 100 years. (Photo by Carrie Levine).
When the U.S. was divvying up land in the West in the late 19th and early 20th centuries, the General Land Office performed surveys so that the land could be parceled and sold. Land was divided into square-mile blocks, with markers used to indicate every corner point. In case a marker was moved, so-called “witness trees” near the stake were identified as reference points. The result of this data is a grid survey of the entire American West.
Using this historic field data, two ecologists at the University of Wyoming, Mark Williams and William Baker, developed a method that claims to calculate the area that a tree occupies, which is then used to calculate a forest's density. This approach is based on the observation that trees create space to keep other trees from cramming next to them, and that this space correlates to a tree's species and size.
To assess the validity of this area-based method of density estimation in the Sierra Nevada, Levine and her co-authors assembled data from plots of mapped trees across the Sierra and Baja California, Mexico. They tested the performance of the area-based method in these mapped stands where the true density was known.
Levine and colleagues found that the area-based method has two basic flaws when applied to the Sierra, the most notable being an inability to actually predict the area that a tree occupies based on its species and size due to a weak relationship between these variables. The other flaw was a failure to account for differences in the number of trees sampled at each corner. The methodological flaws led to an inflated number of trees estimated in a pre-European Sierra Nevada forest, Levine and colleagues argue.
“We have a mapped plot where every tree is measured, so we know the true density,” Levine said.
The study is important not only for the current state of the Sierra Nevada, but for its future.
“As climate changes, we want to have an accurate understanding of the past. This allows us to manage for forests that are resilient to the changes we're expecting in the future,” Levine said.
Throughout the United States, Cooperative Extension's 13,000 academics use new technologies to help solve problems faced by farmers, industries, natural resource managers and local communities, reported John Tibbetts in the AAAS publication Science.
The article included the thoughts of two relatively new UC Cooperative Extension academics and outlined a new UC program to support graduate students interested in cooperative extension careers.
Distinct skills are needed to be an effective cooperative extension academic. The role requires the ability to know and understand how to work with and through people, how to bring about change in communities and how to engage buy-in at the grassroots level.
"You should have good listening skills," added Lenya Quinn-Davidson, UC Cooperative Extension area fire advisor based in Humboldt County.
Quinn-Davidson also said she likes the diversity of her job. “I can be out in the field and then do a radio interview, work on a grant application, or host an event, and I'm always building relationships," she said.
John Battles, forest ecology professor at UC Berkeley said Cooperative Extension can offer an alternative academic career track for many students, but they need a way to learn the skills needed for extension success.
“In extension, you must communicate science effectively to the general public, and you don't have a 50-minute lecture to do it. You need to know how to facilitate a productive discussion in a public meeting, how to run that meeting so that everyone is heard,” he said.
To prepare students for extension jobs, UC Berkeley launched the Graduate Students in Extension program. The internship offers up to a year of funding for graduate students to conduct applied research projects and learn the principles of outreach.
Tapan Pathak, UC Cooperative Extension specialist in climate change adaptation in ag, also commented Tibbetts' article. He said extension specialists have the academic freedom to undertake research in their field as long as it addresses the needs of their clients.
After conducting extensive forest research and taking into consideration all aspects of forest health – including fire and wildlife behavior, water quality and quantity – a group of distinguished scientists have concluded that enough is now known about proposed U.S. Forest Service landscape management treatments for them to be implemented in Sierra Nevada forests.
“There is currently a great need for forest restoration and fire hazard reduction treatments to be implemented at large spatial scales in the Sierra Nevada,” the scientists wrote. “The next one to three decades are a critical period: after this time it may be very difficult to influence the character of Sierra Nevada forests, especially old forest characteristics.”
The scientists' recommendation is in the final report of a unique, 10-year experiment in collaboration: the Sierra Nevada Adaptive Management Project (SNAMP). A 1,000-page final report on the project was submitted to the U.S. Forest Service at the end of 2015. In it, scientists reached 31 points of consensus about managing California forests to reduce wildfire hazards and protect wildlife and human communities.
“SNAMP was founded on a desire to work collaboratively to protect the forests of the Sierra Nevada,” said John Battles, professor of forest ecology in the Department of Environmental Science, Policy and Management at UC Berkeley and SNAMP principle investigator. “The challenges are multifaceted with a huge diversity of perspective among the public, among managers, and among scientists. SNAMP tried to bring all these interests and talents together to safeguard a vital resource and a natural wonder."
SNAMP was created to help develop a collaborative management and monitoring plan consistent with the Sierra Nevada Forest Plan Amendment, signed by regional forester Jack Blackwell on Jan. 21, 2004. The amendment called for the use of fuel reduction treatments – such as prescribed burning, mechanical chopping of underbrush, and harvesting certain trees – in strategically placed areas to slow down potential wildfires and improve forest health.
Because of disagreements over forest treatments in the past, which often led to lawsuits that languished in court for years, the U.S. Forest Service, U.S. Fish and Wildlife Service and the California Natural Resources Agency decided to take a new approach in 2005. They asked the University of California to provide unbiased scientific assessments of the impacts of the proposed treatments. UC was also charged with engaging the public concerned about repercussions of the forest treatments on wildlife habitat and water quality.
The scientific efforts and the forest treatments were all conducted in an open and transparent process. To ensure the greatest number of stakeholders were taking part, SNAMP included a public participation team of social scientists and UC Cooperative Extension outreach professionals to conduct and study the collaboration process.
Susan Kocher, UC Agriculture and Natural Resources Cooperative Extension forestry advisor in the Central Sierra, was a member the project since 2008 and served as the leader of the public participation team during the final two years, succeeding Kimberly Rodrigues, a UC forestry scientist who is now the director of the UC Hopland Research and Extension Center in Mendocino County. Kocher said having outreach and public participation included as a funded part of a science project is unusual.
“We were able to make great strides in getting everybody on the same page,” Kocher said. “That's what our data shows, too.”
A large volume of new scientific information was generated by the science team, and was published in 46 journal articles. The science spread fast and far, according to citation analysis conducted by the public participation team.
“We found that the average time it took for a SNAMP publication to be cited in another journal was about seven months,” Kocher said. “Citations to our articles came from all over the United States and around the globe.”
In addition, SNAMP science-based information was immediately useful to forest managers, according to a 14-page response to the SNAMP final report by the Forest Service, Fish and Wildlife and the California Natural Resources Agency. For example, an excerpt of the response submitted by California Fish and Wildlife noted that “SNAMP proved successful at modifying treatment methodology to meet the ever-changing reality of forest management.”
“The results were able to prove useful for managers past and future regarding how management can be implemented, in the face of wildfires while still retaining important owl nesting/roosting and foraging habitat features in and near owl activity features,” the document said.
SNAMP – funded with $15 million in grants mainly from the U.S. Forest Service, with support from U.S. Fish and Wildlife, California Natural Resources Agency and University of California – ran from 2007 to 2015. The project ended with the submission of the final report that contains details about the study areas, the treatment processes and reports from each of the six science teams. The science teams and their final reports are:
“The integration in this project is also unique,” Kocher said. “Scientists tend to work in their own focus areas, but we can learn a lot from each other's research projects.”
Working together, the scientists looked at all the research outcomes. The first 18 recommendations in the chapter are the direct result of scientific research conducted in SNAMP projects; the remainder of the recommendations are based on other scientific work and research.
Each of the recommendations is linked to a management goal. Some goals may conflict with achieving one or more of the other management goals. This approach to organizing the recommendations was taken to demonstrate that, while many of the management recommendations do not clash, a few may. For example, suggesting treatments across a landscape in a way that minimizes the negative effects on wildlife might reduce the efficiency of treatments aimed at reducing wildfire behavior and impacts.
The next steps are for the U.S. Forest Service to consider and adapt the SNAMP results and recommendations to continue to restore and protect the natural resources at risk in the Sierra.
“My hope is the SNAMP will be seen as a promising first try to apply adaptive management in the Sierra Nevada,” Battles said. “We gained important new insights about the ecology of these forests and we learned how to conduct applied research in an inclusive manner that engages not only scientists from multiple disciplines but also managers and the public."