- Author: Kara Manke
Reposted from Berkeley News
For nearly half a century, lightning-sparked blazes in Yosemite's Illilouette Creek Basin have rippled across the landscape — closely monitored, but largely unchecked. Their flames might explode into plumes of heat that burn whole hillsides at once, or sit smoldering in the underbrush for months.
The result is approximately 60 square miles of forest that look remarkably different from other parts of the Sierra Nevada: Instead of dense, wall-to-wall tree cover — the outcome of more than a century of fire suppression — the landscape is broken up by patches of grassland, shrubland and wet meadows filled with wildflowers more abundant than in other parts of the forest. These gaps in the canopy are often punctuated by the blackened husks of burned trunks or the fresh green of young pines.
“It really is a glimpse into what the Sierra Nevada was like 200 years ago,” said Scott Stephens, a professor of environmental science, policy and management at the University of California, Berkeley, and co-director of Berkeley Forests.
Stephens is the senior author of a new study that gathers together decades of research documenting how the return of wildfire has shaped the ecology of Yosemite National Park's Illilouette Creek Basin and Sequoia and Kings Canyon National Parks' Sugarloaf Creek Basin since the parks adopted policies for the basins — at Illilouette Creek in 1972 and Sugarloaf Creek in 1968 — to allow lightning-ignited fires to burn.
While the prospect of smoke over iconic Half Dome has worried politicians and tourists alike, the work of Stephens and his colleagues demonstrates that allowing frequent fires to burn in these basins has brought undeniable ecological benefits, including boosting plant and pollinator biodiversity, limiting the severity of wildfires and increasing the amount of water available during periods of drought. All these benefits are also likely to make the forest more resilient to the warmer, drier conditions brought by climate change, the research suggests.
“In many ways, fire has successfully been restored to Illilouette, and it has made for a complex mosaic of vegetation with cascading effects on things like water,” said study co-author Brandon Collins, who holds a joint appointment as a research scientist with Berkeley Forests and with the U.S. Forest Service. “In Illilouette, you can have patches of young, regenerating trees from a fire 15 years ago, or areas where a classic understory burn has resulted in big, old, widely-spaced trees. You can even have areas where fire has missed because there's more moisture, such as adjacent to a creek or on the edge of a meadow. All this complexity can happen in a really short amount of space.”
The study findings arrive in the middle of a critical fire season, when drought conditions throughout the western U.S. have already sparked numerous large wildfires, including the Dixie Fire, which, as of Aug. 8, was the second largest wildfire in California history. While climate change has played a role in increasing the severity of these fires, Stephens said, Illilouette Creek Basin serves as an example of how current forest conditions in the Sierra — largely shaped by decades of fire suppression — are also driving these massive blazes.
“I think climate change is no more than 20 to 25% responsible for our current fire problems in the state, and most of it is due to the way our forests are,” Stephens said. “Illilouette Basin is one of the few places in the state that actually provides that information, because there is no evidence of changes in fire size or in the severity of fires that burn in the area. So, even though the ecosystem is being impacted by climate change, its feedbacks are so profound that it's not changing the fire regime at all.”
Returning fire to Yosemite
For millennia, wildfires sparked by lightning, or lit by Native American tribes, regularly shaped the landscape of the western U.S., not only causing destruction, but also triggering necessary cycles of rebirth and regeneration. However, the arrival of European colonists in the late 1800s, followed by formation of the U.S. Forest Service in 1905, ushered in an era in which fire was viewed as the enemy of humans and forests alike, and the vast majority of wildfires were quickly extinguished.
By the 1940s and 1950s, a number of forest managers and ecologists had begun to question the wisdom of fire suppression, noting that the practice was eliminating valuable wildlife habitat and increasing the severity of fires by allowing decades of fuel buildup. These fire proponents included A. Starker Leopold, an acclaimed conservationist and professor of zoology and forestry at UC Berkeley, as well as Harold Biswell, a professor at UC Berkeley's School of Forestry.
In response to a foundational 1963 report led by Leopold, the U.S. National Park Service changed its policy in 1968 to allow lightning fires to burn within special fire management zones — usually remote regions at high elevations — where danger to human settlements was low. Sequoia and Kings Canyon National Parks established the first fire management zone in 1968, followed by Yosemite National Park in 1972.
“I think it was finally recognized that fire is an integral piece of these ecosystems, and there were a few key people who were willing to take the risk of letting these fires happen,” Collins said.
‘It isn't always clean, and it's not always nice'
Between 1973 and 2016, Illilouette Creek Basin experienced 21 fires larger than 40 hectares — approximately equal to 75 football fields — while Sugarloaf experienced 10 fires of that size. In Illilouette, the result today is a forest that may look a bit messy to the untrained eye, but it holds a lot of resilience.
“When some people visit Illilouette, they say, ‘Look at all these dead trees!'” Stephens said. “I think we have this idea that forests need to be green all the time and made up with only big trees. But it turns out that no forest can do that. It has to be able to grow young trees and regenerate. Illilouette is doing that, but it isn't always clean, and it's not always nice.”
In Illilouette, wildfire has created a more diverse array of habitats for animals like bees and bats, while allowing a variety of plant life to flourish. The detailed history of wildfires in Illilouette has also provided foresters with valuable information on how the impact of one wildfire on landscape and vegetation can influence the trajectory of the next wildfire.
“Since fires are generally allowed to burn freely in Illilouette, we could look at what happens when two fires have burned close to each other: When does the second fire burn into the area that was burned by the first fire, and when does it stop at the previous perimeter?” Collins said. “We found that it really depended on the amount of time that had passed since the first fire. If it had been nine years or under, fires almost never burned into a previous fire perimeter.”
Collins said that Illilouette has also given forest managers a unique opportunity to study how wildfire behaves under a variety of conditions, rather than only at its most dire.
“One of the things that's kind of perverse about the fire suppression policy is that we actually constrain fires to only burn under the worst conditions. If the fire is mellow, that's a good time to put it out, and, as a result, they only burn when we can't put them out,” Collins said. “But by letting these fires burn (in Illilouette), they're able to experience the full range of weather conditions. On bad days, some of these fires have really put up a pretty good plume. But on the flip side, they also get to burn under more moderate conditions, too, and it makes for really varied effects.”
Returning fire to Illilouette has also had the somewhat counterintuitive impact of increasing the availability of water in the basin, a key finding as California weathers yet another year of extreme drought.
Study co-author Gabrielle Boisramé, an assistant research professor at the Desert Research Institute in Nevada, began studying water in Illilouette as a Ph.D. student in environmental engineering at UC Berkeley. Her simulations and measurements indicate that small gaps in the tree canopy created by wildfires have allowed more water from snow and rainfall to reach the ground, while also reducing the number of trees competing for water resources. As a result, soil moisture in some locations in Illilouette increased as much as 30% between 1969 and 2012, which likely contributed to very low tree mortality in the basin during the drought years of 2014 and 2015.
Measurements also indicate that streamflow out of Illilouette Creek Basin has increased slightly since the managed wildfire program began, while streamflow out of other similar watersheds in the Sierras have all decreased. Boosting the amount of water that flows downstream is likely to benefit both the humans and the aquatic ecosystems that depend on this precious resource.
“There's more and more work being done that examines the effects of fire on hydrology, but most of the other research is looking at the effects of catastrophic fires that burned up an entire forest,” Boisramé said. “As far as we know, we're the only ones in the western U.S. studying a restored fire regime, where we're not just looking at one individual fire, but a number of fires of mixed severity that have occurred over natural intervals of time. There just aren't that many places to study the long-term effects of these repeated wildfires because Sugarloaf and Illilouette were the first areas in California — really the first western mountain watersheds — where they started allowing fires to burn most of the time.”
Fighting for fire
Most U.S. national parks now practice some form of fire use, rather than full fire suppression, and in 1974, the National Forest Service also changed its policy to also allow some fires to burn on its lands, although areas of fire use are rare in this agency. However, these federal fire use policies have struggled to gain a foothold, largely because of the inherent risks involved in managing wildfire.
Even in Sugarloaf Creek Basin, where many fires have been allowed to burn, there has also been significantly more fire suppression than in Illilouette, the study found. As a result, the ecological benefits in Sugarloaf are not as pronounced as those in Illilouette.
“I think one of the key things to recognize is that the landscape in Illilouette was already somewhat unique, partly because it is at slightly higher elevation than a lot of the forests we manage,” Collins said. “As a result, it already had a mix of vegetation with patches of meadows and rock, and I think maybe that gave managers a little more ease in letting fire happen there. It doesn't have the potential to really push off a giant megafire because it lacks the continuity that some of these other areas have.”
While both naturally-sparked fires and prescribed burns could help large swathes of the Sierra forest become more resilient to both drought and high severity fire, opposition to national “let it burn” policies in California remains strong, with state and local fire agencies often favoring the safety of fire suppression.
Collins and Stephens both acknowledge that the current fuel density in much of the Sierra, mixed with the hotter, drier conditions already triggered by climate change, has made managing wildfire even riskier than it was when forest managers started allowing fires to burn in Yosemite in 1972. However, they argue, fire suppression will never succeed in the long term, because the longer that forest fuel sources are allowed to build up, the more likely it becomes that wildfires will turn catastrophic when they are finally sparked.
“In order to actually allow this to happen, political and public institutions need to be willing to accommodate risk, because there will be some unpredictability. There are going to be fires that get larger, and more severe burning in places that have had very little fire for a century or more,” Stephens said. “We can't guarantee that Illilouette is going to be the new outcome, because it started when climate change was not nearly as severe. So, political institutions will have to accommodate that, or the first fire that doesn't do exactly what we hope will shut down the whole program.”
Collins and Stephens also advocate for more aggressive prescribed burning and restoration thinning throughout the Sierra to help get the forests to a place where lightning-sparked fires can be allowed to burn more safely.
Stephens credits strong, early leadership at Yosemite — including that of study co-author Jan W. van Wagtendok, who received a Ph.D. from UC Berkeley in 1972 and went on to serve as a research scientist at Yosemite for most of his career — for taking the huge risk of launching the program and allowing early fires to burn in the park.
“It's been 50 years now, but I think what we've learned helps us understand what is possible,” Stephens said. “We have 10 to 20 years to actually change the trajectory of the forest ecosystems in our state, and if we don't change them in 10 or 20 years, the forest ecosystems are going to change right in front of our eyes, and we're just going to be passengers. That's why it's so important to continue this work.”
Previous funding from the U.S. Joint Fire Science Program, UC ANR Competitive Grants Program, and the National Science Foundation's Critical Zone Collaborate Network (award number 2011346) supported the research in this paper.
Study co-authors also include Sally Thompson of the University of Western Australia; Lauren C. Ponisio of the University of Oregon, Eugene; Ekaterina Rakhmatulina, Jens Stevens and Zachary L. Steel of UC Berkeley; and Kate Wilkin of San Jose State University.
- Author: UC Berkeley Public Affairs
Reposted from UC Berkeley College of Natural Resources news
A Berkeley researcher in the Department of Environmental Science, Policy, and Management travelled to Washington, D.C., to testify on Tuesday before the U.S. House Subcommittee on Energy and the Subcommittee on Environment and Climate Change.
The hearing, titled “Out of Control: the Impact of Wildfires on Our Power Sector and the Environment,” included testimony from industry officials and specialists on a range of issues including wildfire, forest management, air quality, changing climate, and the power sector.
Brandon Collins, a forest scientist in the Stephens Lab and the Berkeley Forests group, discussed how forests historically had frequent fire of low- to moderate-severity but that a century of logging and fire suppression severely altered the landscape. He noted that the condition of contemporary forests—which now regularly experience large-scale tree mortality from such events as insect outbreaks and drought—need diverse management approaches to prevent more severe wildfires.
“Our great challenge is to manage forests such that they can tolerate fire, even under more extreme weather conditions, and still retain their fundamental character,” wrote Collins in his testimony.
Collins pointed to increases in tree density, greater amounts of dead biomass, the loss of larger trees, and increasingly homogenized vegetation patterns as factors that contribute to the greater intensity of wildfires. He said that—against a backdrop of complex land management, ownership, and societal constraints—forest managers must employ a diversified approach to forest restoration, even as climate change exacerbates many problems.
“Our current rate of forest restoration is falling woefully short of what is needed in these forests,” commented Collins. “It is time to prioritize forest health and resilience, even over other resource concerns, in order to ensure their continued provisioning of services we depend on.”
- Author: Kara Manke
Spotted owl populations are in decline all along the West Coast, and as climate change increases the risk of large and destructive wildfires in the region, these iconic animals face the real threat of losing even more of their forest habitat.
Rather than attempting to preserve the owl's remaining habitat exactly as is, wildfire management — through prescribed burning and restoration thinning — could help save the species, argues a new paper by fire ecologists and wildlife biologists and appearing today (July 2 ) in the journal, Frontiers in Ecology and the Environment.
The paper compares the plight of the owl with that of another iconic threatened species, the red-cockaded woodpecker, which has made significant comebacks in recent years — thanks, in part, to active forest management in the southern pine forests that the woodpecker calls home. Though the habitat needs of the two birds are different, both occupy forests that once harbored frequent blazes before fire suppression became the norm.
“In the South, the Endangered Species Act has been used as a vehicle to empower forest restoration through prescribed burning and restoration thinning, and the outcome for the red-cockaded woodpecker has been positive and enduring,” said Scott Stephens, a professor of environmental science, policy and management at the University of California, Berkeley, and lead author on the study.
“In the West, it's just totally the opposite,” Stephens added. “Even though both places physically have strong connections to frequent fire, the feeling here is that the best thing to do is to try to protect what we have and not allow the return of frequent fire — but that's really difficult when you have unbridled fires just ripping through the landscape.”
A tale of two birds
Spotted owls make their homes in the dense forests of the Western and Southwestern U.S., feeding on flying squirrels and woodrats and nesting in broken-off treetops or tree hollows. Red-cockaded woodpeckers, meanwhile, reside in pine stands in the Southeastern U.S., provisioning nests from nest boxes or hollowed-out cavities in living pine trees and eating insects pried from under tree bark.
Development and logging have robbed both species of much of their former habitat, and their populations have both taken a hit: Partners in Flight estimates the global breeding population of spotted owls to be at 15,000 individuals.
What habitat remains is now largely protected under the Endangered Species Act — but when it comes to fire and forest management, the act has been interpreted in dramatically different ways in the two regions, said paper co-author Leda Kobziar, associate clinical professor of wildland fire science at the University of Idaho.
“In the South, the act is interpreted to support active management through forest thinning and prescribed burning, and in the West, it is interpreted to exclude most fires and active management from protected areas surrounding spotted owl nests,” Kobziar said.
One critical difference is the degree to which active management in red-cockaded woodpecker habitat provides complementary benefits. “In the South, active management is known to reduce wildfire hazards, and it benefits local economies, along with a host of other fire-dependent species. In the West, those complementary benefits are less well-defined,” Kobziar said.
Another part of the reason for the discrepancy is perceived differences in the habitat preferences of the two birds, Kobziar explains. Red-cockaded woodpeckers live in more open, mature pine forests that result when low-intensity natural or prescribed burns limit the development of a forest midstory, where woodpecker predators take cover. Meanwhile, spotted owls generally prefer the dense, multi-layered forests that grow when fire is excluded.
However, suppressing all fires in order to encourage growth of these dense canopies also creates conditions that are ripe for large, severe wildfires that can take out not just the smaller trees, but entire forests, obliterating swaths of owl habitat in the process. The 2014 King Fire, for example, tore through regions of the Eldorado National Forest that were home to a long-term study of the California spotted owl and caused the bird's largest population decline in the 23-year history of the study.
“A key question to be asking is: Where would owl habitats be with more characteristic fire regimes, and could we tailor landscape conditions where these habitats are less vulnerable and more supportive of today's wildfires?” said co-author Paul Hessburg, a research landscape ecologist with the U.S. Forest Service Pacific Northwest Research Station.
The solution would mean, “essentially creating less habitat in order to have more in the long run,” he said.
Fighting fire with fire
Before European settlement, many small- to medium-sized wildfires burned through the forests of the Southeastern and Western U.S., sparked by lightning or intentionally lit by native peoples to produce food, clear land or drive game. These fires would gobble up the dead wood, seedlings and saplings that made up the forest understory, while leaving taller, older trees standing and marked with fire scars recorded in their growth rings that fire ecologists use to track the frequency of historical fires.
In the mountainous landscape of the West, these fires didn't strike uniformly everywhere, to the potential benefit of the owls, Hessburg said. “If I took you back in the way-back machine 200 years ago, you would have seen that fire regimes in the Cascade Mountains differed very much by topographic setting,” he said. “Ridgetops and south slopes would often get pounded with lightning and fires, and so tree cover would be sparse. But in shaded and cool valley bottoms and north slopes, you would see complex layered forests, and some of these would have been incredible owl habitats.”
Targeted restoration thinning and prescribed burning on ridgetops and dry southern slopes where fire used to be a frequent visitor, while leaving valley bottoms and northern slopes to develop into complex forest, could be a way to discourage large wildfires from ripping through vast landscapes, while maintaining owl habitat in a more fire-protected context.
New evidence also hints that owls may not be so dependent on dense understory canopies as once thought, the paper notes. Recent findings indicate that other aspects of forest structure, particularly the presence of large, old, tall trees, may be more important to the owls. These findings hint that prescribed burning and restoration thinning to reduce the size and severity of wildfires may not be damaging to owl habitat, even in the short term.
“We're treating the habitat as if we know precisely what habitat characteristics are preferred. It might be that these birds are tolerant of a broader range of characteristics that would enable things like fuels reduction to protect them from high-intensity wildfires,” Kobziar said.
“The South has melded fire and rare species management in a holistic way, but in the West, we're doing one or the other — (in) most places (where) we do forest restoration, we are trying to avoid owls,” Stephens said. “But the King Fire showed that owls and their habitats are vulnerable to large wildfires. More restoration thinning and prescribed burning could help us keep the habitat that we have now, modify it and actually make it more sustainable in the future.”
Other co-authors on the study include Brandon M. Collins of UC Berkeley; Raymond Davis, Joseph Ganey, James M. Guldin, Serra Hoagland, John J. Keane, Warren Montague, Malcolm North and Thomas A. Spies of the U.S. Forest Service; Peter Z. Fulé of Northern Arizona University; William Gaines of the Washington Conservation Science Institute; Kevin Hiers of the Tall Timbers Research Station; Ronald E. Masters of the University of Wisconsin-Stevens Point and Ann E. McKellar of Environment and Climate Change Canada.
- Author: Kim Ingram
- Posted by: Susie Kocher
Reposted from the UCANR Green Blog
Thinning a forest of woody materials has multiple objectives. It can increase the resiliency of the remaining trees from the effects of fire, drought, pest and disease; it can improve habitat quality for wildlife including watersheds; and it can make it easier for firefighters to protect human lives and livelihoods when a fire is burning. There are several ways thinning is carried out: cable logging, feller bunching, conventional tractor skidding, hand-thinning and piling, and mastication. One of the issues with thinning is the disposal of biomass that is non-merchantable (e.g., branches, tree tops, small diameter trees). Typically this material goes into large slash piles. For the most part, these piles are left in the forest to break down naturally under winter rain and snows, and are later burned. Because of strict air quality rules, forest managers have very small windows of opportunity to burn these piles, so they are often left on the landscape for many years, sometimes becoming a fire hazard themselves.
Forested communities are searching for ways to deal with this residual biomass that will improve the health of the forest ecosystem; improve and protect critical watersheds and wildlife habitat; reduce the amount of air pollution by removing the piles instead of burning them; and reduce the critical fire danger to their communities. The Placer County Biomass Program is taking up this challenge by chipping the slash piles and trucking the chips to a biomass facility to be converted into electricity.
Outside of Foresthill, Calif., the Tahoe National Forest American River Ranger District and the Sierra Nevada Adaptive Management Project (SNAMP) have been collaborating on a study of forest fuels reduction treatments carried out on national forests. The eight-year ‘Last Chance’ study involves independent third party research by University of California scientists of the integrated effects of forest thinning on fire hazard, forest health, wildlife, water quality and quantity, and public participation. The Placer County Biomass Program, in conjunction with the Tahoe National Forest, the Sierra Nevada Conservancy (SNC) and the Placer County Air Pollution Control District, proposes to remove some of the biomass waste from the Last Chance project to provide an alternative to open burning of the piles. Local contractors are hired to grind the material on-site, load the material into chip vans, and bring the material to market within 60 miles of the Last Chance site to create green, renewable electricity. Placer County estimates that roughly 3,000 Bone Dry Tons (BDTs) of biomass can be removed. According to UC researchers, one BDT burned in a typical commercial boiler fuel will produce 10,000 pounds of steam and 10,000 pounds of steam will produce about 1,000 horsepower or generate 1 megawatt hour (MWH) of electricity.
The economics of this project will be used as part of the assessment of locating a biomass energy facility in the Foresthill area. The removal of these biomass piles will greatly reduce the possibility of catastrophic fire to the local communities on the Foresthill Divide. The improved forest and watershed health will be noticed by the local community and the surrounding county which derives recreation and watershed benefits from the American River area. In addition, several tons of air pollutants will be avoided by removing the pile burns from this area which is currently a federal non-attainment basin that carries both business and health risks to the local population.
Though this project is of benefit to the Foresthill community, other communities in the wild-land urban interface aren’t as lucky. According to Brandon Collins, research scientist at the Pacific Southwest Research Station and UC Berkeley, the lack of funding to chip and remove slash piles and the lack of infrastructure or facilities to take the chips to, makes it impossible at this time to remove that biomass at a larger scale.
“There is so much woody material on the landscape as a result of fire exclusion, it could take decades to really get a handle on it," Collins said. "However, any effort to remove thinning residues from the forest and to also get a benefit from it, such as energy, is great and should be supported.”