Posts Tagged: forest
Mechanical thinning of overstocked forests, prescribed burning and managed wildfire now being carried out to enhance fire protection of California's forests provide many benefits, or ecosystem services, that people depend on.
In a paper published in Restoration Ecology, researchers at UC Merced, UC ANR and UC Irvine reported that stakeholders perceived fire protection as central to forest restoration, with multiple other ecosystem services also depending on wildfire severity. Researcher Max Eriksson, lead author on the paper, noted that "forest restoration involves multiple fuels-reduction actions that were perceived as benefiting fire protection, with some also offering strong benefits to other ecosystem services such as air quality, wildlife habitat, soil retention and water supply."
The study showed that the total effect of an action such as mechanical thinning of forests aimed at reducing fuels includes not only the direct effect on reducing wildfire severity, but also secondary effects that improving fire protection has on benefits such as providing water and hydroelectricity for agriculture and communities across the state or storing carbon and reducing carbon-dioxide emissions from wildfire to the atmosphere. Fire management is therefore central to human well-being.
Across the western United States, researchers are addressing the huge challenge of transforming forest management from the historical goal of maximum resource extraction (e.g., timber production) to a paradigm built on multiple benefits, or ecosystem services.
The study involved a series of virtual workshops with natural-resource professionals, including forest managers, to understand their perceived effects of management actions on ecosystem services and the interactions of the various services. Eleven ecosystem services and nine currently used management actions were considered.
Safeeq Khan, co-author and UC ANR Cooperative Extension specialist in water and watershed sciences, adds, "Understanding both actual and perceived benefits provided by restoring overstocked forests is crucial to guiding the choice of management actions, public support, policy initiatives and investments by beneficiaries, i.e., monetizing ecosystem services."
UC Merced Professor and co-author Roger Bales points out that "reducing fuel loads is increasingly being recognized as an effective measure to transition our forests across the western United States from a destructive to a beneficial wildfire regime."
Bales adds, "Our research supports the perception that California's wildfire-vulnerable forests should primarily and urgently be restored to conditions that better regulate wildfire severity, and thus provide greater fire protection and other ecosystem-service benefits. Lower-severity wildfire is a natural and beneficial part of these ecosystems."
An important contribution of this study is the breadth of both ecosystem-service benefits and management actions considered. Study collaborator and ecosystem-service expert Benis Egoh, an assistant professor at UC Irvine, points out that, "This research recognized that given the complexity of forest ecosystems across the western United States, the investments required and the management constraints, increasing forest resilience requires a range of actions." She adds, "Accounting for perceived interactions of ecosystem services is key to multi-benefit valuation of restoration investments and to monetizing those benefits in equitable ways."
UCCE forest advisor helps landowners, community groups determine best project options
As Californians prepare for another year of drought and an anticipated intense fire season, landowners and organizations across California have been working to reduce forest fuels – flammable woody material – that can endanger their properties and communities.
For many of them, however, their urgent efforts hit a sizable speed bump: a massive rulebook that describes, amid a thicket of other information, the permits required before people can treat or remove fuels – as well as a litany of attached requirements, restrictions and stipulations.
“The California Forest Practice Rules are 410 pages, in font size 6,” said Yana Valachovic, UC Cooperative Extension forest advisor for Humboldt and Del Norte counties and registered professional forester. “Trying to figure out what permit vehicles make sense in the rulebook is not easy even for the experienced professional forester.”
To assist private landowners and community groups in deciphering the rules and determining their most cost-effective options, Valachovic took the lead in writing a new guide, “Planning and Permitting Forest Fuel-Reduction Projects on Private Lands in California,” available as a free resource in the UC Agriculture and Natural Resources catalog.
“We tried to create a system where all the permits are laid out side-by-side, and put in a decision tree framework to help make it easier,” said Valachovic, highlighting the publication's tables that break down the project goals and parameters a permit applicant should think about when weighing their choices.
Considerations include whether the project is pre- or post-wildfire, the location and dimensions of trees targeted for removal, the conditions of the site before and after the project, potential time limits, commercial options, and, crucially, budget constraints – given that the permitting process could comprise up to one-third of total project costs.
A primer for planning and preparation
Chris Curtis, the unit forester for CAL FIRE's Humboldt-Del Norte Unit, said that he and his colleagues are grateful for this new tool and plan to use it as an “over the counter” handout for community members. He added that the charts summarizing timber-harvesting regulations and possible funding sources are especially helpful.
The publication helps prepare the landowner or community entity (such as Resource Conservation Districts, Fire Safe Councils or other concerned groups) for the types of questions that might come up in preliminary planning conversations with a registered professional forester or RPF.
Just as a homeowner would talk with a contractor before tackling a construction project, landowners and community groups must consult with an RPF, Valachovic said. RPFs have the specialized knowledge of forest practice rules and regulations related to water, air quality and endangered species protections, and the license to file the permitting documents.
“That's what I do in my job: Landowners come to me and we start talking about goals and objectives,” she said. “We start thinking about potential timelines – which goals are short-term, which are long-term – and how we can put an operational plan together to help those landowners achieve their goals.”
Long-term projects, short-term actions
Among the many practical tips outlined in this guide, Valachovic emphasized one in particular: for landowners dipping their toes into fuel reduction for the first time, keep the project “simple and realistic.”
In the short-term, however, Valachovic stressed that the extremely dry conditions across the state make it imperative for Californians to harden their homes, manage the fuels (i.e., landscape plants, stored wood, tall grass, etc.) immediately adjacent to their homes, and devise and review family emergency plans; see UC ANR's Wildfire Preparation page for detailed information and resources.
“There are a lot of immediate actions that people can be doing this year to help mitigate their wildfire risks and prepare for the unexpected,” she said.
In addition to Valachovic, co-authors of “Planning and Permitting Forest Fuel-Reduction Projects on Private Lands in California” are Jared Gerstein of BBW Associates and Brita Goldstein, UCCE staff research associate in Humboldt and Del Norte counties; both are registered professional foresters./h3>/h3>/h3>
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.
“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.
“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.”
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.”
Study finds resilient, frequent-fire forests have far fewer trees
What does a “resilient” forest look like in California's Sierra Nevada? A lot fewer trees than we're used to, according to a study of frequent-fire forests from the University of California, Davis.
More than a century ago, Sierra Nevada forests faced almost no competition from neighboring trees for resources. The tree densities of the late 1800s would astonish most Californians today. Because of fire suppression, trees in current forests live alongside six to seven times as many trees as their ancestors did — competing for less water amid drier and hotter conditions.
The study, published in the journal Forest Ecology and Management, suggests that low-density stands that largely eliminate tree competition are key to creating forests resilient to the multiple stressors of severe wildfire, drought, bark beetles and climate change.
This approach would be a significant departure from current management strategies, which use competition among trees to direct forest development.
But first, the study asks: Just what does “resilience” even mean? Increasingly appearing in management plans, the term has been vague and difficult to quantify. The authors developed this working definition: “Resilience is a measure of the forest's adaptability to a range of stresses and reflects the functional integrity of the ecosystem.”
They also found that a common forestry tool — the Stand Density Index, or SDI — is effective for assessing a forest's resilience.
“Resilient forests respond to a range of stressors, not just one,” said lead author Malcolm North, an affiliate professor of forest ecology with the UC Davis Department of Plant Sciences and a research ecologist with the U.S. Forest Service, Pacific Southwest Research Station. “‘Resistance' is about surviving a particular stress, like fire — but there's a lot more going on in these forests, particularly with the strain of climate change.”
For fire-adapted forests in the Sierra, managing for resilience requires drastically reducing densities — as much as 80% of trees, in some cases.
“Treatments for restoring resilience in today's forests will need to be much more intensive then the current focus on fuels reduction,” said Scott Stephens of UC Berkeley, a co-author on the paper.
The study compared large-scale historical and contemporary datasets and forest conditions in the southern and central Sierra Nevada, from Sequoia National Forest to the Stanislaus National Forest. It found that between 1911 and 2011, tree densities increased six- to seven-fold while average tree size was reduced by half.
A century ago, both stand densities and competition were low. More than three-quarters of forest stands had low or no competition to slow a tree's growth and reduce its vigor. In contrast, nearly all — 82%-95% — of modern frequent-fire forests are considered in “full competition.”
The study indicates that forests with very low tree densities can be more resilient to compounded threats of fire, drought and other climate stressors while maintaining healthy water quality, wildlife habitat and other natural benefits. Forests burned by high-severity fires or killed by drought lose such ecosystem services.
The authors say the 2012-2016 drought, in which nearly 150 million trees died from drought-induced bark beetle infestations, served as a wake-up call to the forestry community that different approaches are required to help forests confront multiple threats, not only severe wildfires.
A shift away from managing for competitive forests and toward eliminating competition could allow the few to thrive and be more resilient.
“People have grown accustomed to the high-density forest we live in,” North said. “Most people would be surprised to see what these forests once looked like when frequent surface fires kept them at very low densities. But taking out smaller trees and leaving trees able to get through fire and drought leaves a pretty impressive forest. It does mean creating very open conditions with little inter-tree competition. But there's a lot of historical data that supports this.”
“We think resilient forests can be created, but it requires drastically reducing tree density until there's little to no competition,” said Brandon Collins of UC Berkeley, another co-author on the paper. “Doing this will allow these forests to adapt to future climate.”
Additional co-authors include Ryan Tompkins of UC Cooperative Extension, and Alexis Bernal and Robert York of UC Berkeley.
The study was funded by the National Park Service Pacific West Region, U.S. Forest Service Pacific Southwest Research Station, U.S. Joint Fire Sciences Program, and the UC Agriculture and Natural Resources Division./h3>/h3>/h3>/h2>