- Author: Sarah Nightingale
Reposted from University of California News
When plant matter burns, it releases a complex mixture of gases and aerosols into the atmosphere. In forests subject to air pollution, these emissions may be more toxic than in areas of good air quality, according to a new study by the University of California, Riverside and the U.S. Forest Service's Pacific Southwest Research Station.
The results suggest biomass burning of polluted forest fuels may exacerbate poor air quality—and related health concerns—in some of the world's most heavily polluted areas, among them, the Los Angeles metropolitan area, which is expected to suffer from more wildfires as drought conditions continue.
The study, which was led by Akua Asa-Awuku, a researcher at the Center for Environmental Research and Technology (CE-CERT) at UC Riverside's Bourns College of Engineering, was published online recently (March 2) in the journal Environmental Research Letters.
As people burn fuels—in cars, power plants and factories—nitrogen is released into the atmosphere and absorbed by plants. While essential for plant growth, an over-abundance of this biologically-available nitrogen can result in ‘nitrogen saturation,' a phenomenon previously reported by Forest Service scientists in Riverside. Nitrogen saturation can cause a cascade of adverse effects including a decrease in biodiversity, changes in plant species, soil acidification and water contamination.
In this paper, UCR and Forest Service researchers teamed up to explore a previously unstudied aspect of nitrogen saturation: its effect on the gases and aerosols released during burning of forest fuels from an area experiencing nitrogen saturation.
Polluted sites released up to 30 percent more nitrogen oxides than clean sites
Scientists conducted the study in the San Bernardino Mountains, a 60-mile stretch of federal and private forest land to the east of the Los Angeles metropolitan area. Since the pollution concentration decreases from west to east, as the distance from Los Angeles increases, the forests offered a rare opportunity to compare emissions from wildland fuels subjected to different levels of chronic air pollution. At sites 55 miles apart, the researchers collected recently deposited material from the forest floor, called litter, which is a primary fuel in these forests. Both sites have a similar mixture of conifer tree species, and, at the time of collection, had experienced similar temperatures and rainfall.
As shown in previous studies, the litter from the polluted site, which had endured high levels of atmospheric nitrogen oxides and ozone, had higher nitrogen content than litter from the clean site. The researchers then burned the litter in controlled lab tests, collected the emissions and analyzed them. The results showed:
- Fuel from the polluted site released more nitrogen oxides, which contribute to the formation of smog and ozone. In some cases, polluted fuels released 30 percent more nitrogen oxides than fuels from the clean site.
- Polluted fuels released more small fine particles (PM<2.5), which are known cause of respiratory health problems.
- The composition of the particles from polluted regions were different; they were less likely to evaporate but underwent similar atmospheric processing as emissions from clean fuels exposed to sunlight.
Implications for agencies in charge of controlled burns
Asa-Awuku, an associate professor of chemical and environmental engineering at the CE-CERT, said agencies that oversee prescribed burns should consider these findings when they predict the likely impact of prescribed burning of forest fuels in areas subjected to chronic air pollution.
“The environmental impact of prescribed burns has historically been based on data from clean fuels in areas of good air quality, so we have likely been under-predicting the impact of biomass emissions in polluted areas,” Asa-Awuku said.
She added that the study supports growing evidence that humans need to reduce our pollutant footprint associated with burning fossil fuels.
“This study, and specifically the concern that biomass grown and burned in polluted areas is potentially more toxic to human health, is additional evidence that human activities have consequences not yet explored and therefore not understood,” she said.
The research was conducted by Asa-Awuku and Michael Giordano, at UCR's CE-CERT, and Research Forester David Weise and Physical Science Technician Joey Chong from the Forest Service's Pacific Southwest Research Station.
Headquartered in Albany, Calif., the Pacific Southwest Research Station develops and communicates science needed to sustain forest ecosystems and other benefits to society. It has research facilities in California, Hawaii and the U.S.–affiliated Pacific Islands. For more information, visit www.fs.fed.us/psw/./h3>/h3>
- Author: Jeannette Warnert
Reposted from the UCANR Green blog
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:
- Fire and forest ecosystem health
- Spatial - The study of forest canopy and understory with remote sensing technology called lidar, which uses reflected light for analysis.
- Wildlife: California spotted owl – A bird that is dependent on high-canopy forests.
- Wildlife: Pacific fisher – A weasel-like nocturnal animal that roams a wide area and nests in the hollows of old-growth trees.
- Water quality and quality
- Public participation
A key chapter in the publication is titled Integrated Management Recommendations. In it, the 31 points of consensus are outlined.
“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."
- Author: Glen Martin
Reprinted from California Magazine
The recent rains have blunted the psychological impact of California's four-year drought, washing down the streets, perking up the landscaping, and heightening anticipation for a stormy El Nino-driven winter. We know, however, that one wet year is highly unlikely to end water shortages. What we may not fully grasp is that the damage done to the state's forests is so far reaching that it may be permanent.
How bad is it? Really, really bad. Horrendous, in fact. Sally Thompson, an assistant professor in UC Berkeley's department of civil and environmental engineering, cites the status of the state's iconic giant sequoias as an example. Thompson notes that Cal biology professor Todd Dawson has been monitoring the biggest trees on earth, “and has found that they're extremely stressed. They're dropping leaves—some of them may die. These are trees that have lived 3,000 years, enduring a wide range of environmental conditions, including other droughts. And now they're being killed by this drought. That's suggestive of what we're facing. We're heading into uncharted territory.”
And it's not just giant sequoias. Virtually all of California's trees are drought-stressed, and many are going down for the count. Thompson observes the U.S. Forest Service conducted flights over 8.3 million acres of woodland in the southern Sierra, the Central Coast and Southern California in April and concluded that about 10 percent of the conifers and oaks—about 12.5 million trees—had died in recent months. They had either expired directly from drought or succumbed to bark beetles, which attack weakened trees.
The situation has only grown more grim. Two weeks ago, Gov. Jerry Brown declared a state of emergency, warning that the U.S. Forest Service estimates “more than 22 million trees are dead and that tens of millions more are likely to die by the end of this year.” He asked for federal assistance and called for an accelerated program to cut and clear dead trees, expand the practice of prescribed burns and temporarily allow more burning of wood waste.
Greg Asner, a biologist with the Carnegie Institute for Science, used spectrometers and lasers to evaluate forest canopies on flights out of Sacramento and Bakersfield. The procedures yielded 3-D topographic displays that show the forest in varying shades of blue (healthy) yellow (somewhat stressed) and red (deeply stressed to dying or dead). Bottom line: There's a lot of red in them thar hills. Asner concluded about 20 percent of California's forests are doomed—up to 120 million trees.
The images reveal the trees are dying in a mosaic pattern, says Thompson.
“You'll see patches of dying trees in the middle of healthier forest,” she says. “That's probably due to such things as south-facing slopes or shallow soils. You'd expect such areas to experience (drought-related) stress first. But there's a tremendous volume of dead wood building up all across the forests, and that's pointing to a future that is potentially very
Such a vast accumulation of fuels could lead to wildfires that are perhaps unprecedented in their ferocity. They could be so intense and of such a vast scale that they could lead to broad “ecotonal shift” —the evolution of entire forests from one vegetative regime to another. Ponderosa pine forests, for example, could convert to chaparral fields. Oak woodlands could change to grassy savannas. (As California previously noted, such ecotonal changes already may be occurring on Mt. Laguna in Southern California.)
That all sounds pretty apocalyptic no matter how you burn it, but Thompson observes we don't have to just sit back and take it. It turns out there's quite a bit that could be done to fireproof our forests—and perhaps increase water availability in the process. All it will take is a fair amount of money and political will.
“It's clear that there is more standing biomass—trees—in our forests than existed before active fire suppression began a century or so ago,” says Thompson. “Studies show that the canopies are heavier, and the forests are more vulnerable to fire as a result.”
A little background: Prior to Euro-American settlement, California's coniferous forests were characterized by extremely large, widely-spaced trees. Annals of the day—both textual and pictorial— made it clear that you could ride a horse through the forests unimpeded. There was little or no fuel (branches and dead trees) on the ground. The character of the forests was due to the occurrence of fire, both natural and human-induced; California's natives burned the forests periodically to make hunting easier and encourage the growth of food plants, including acorn-bearing oaks, seed-producing grasses, and bulbs.
The good news: The forests of our forebears probably can be reclaimed. All we have to do is burn and cut down a lot of trees.
In the old days, fire noodled around in a low-energy fashion on the forest floors, killing insect pests, nibbling back the underbrush, and converting deadwood to ashes that ultimately nourished the great pines and firs. Today, wildfires rip through entire landscapes of closely-packed trees, immolating everything down to mineral earth.
“Ultimately, the fires can be so intense that they take out all tree seed sources,” says Thompson, “so the system shifts to chaparral.”
Today's dense forests also have less biodiversity and suck up much more water than the forests of yesteryear. Thompson says studies of today's Sierra Nevada forests indicate they transpire 35 percent more water—that is, extract it from the ground through the roots and transfer it to the air as vapor via foliage—than 19th Century forests.
The good news: The biologically rich, fire resilient and amply watered forests of our forebears probably can be reclaimed. All we have to do is burn and cut down a lot of trees.
“There are three ways to go about it,” says Thompson. “Mechanical thinning, prescribed fire, and managed fire.”
Mechanical thinning would be the removal of trees by chainsaws or heavy equipment. Prescribed fire would be controlled burning—setting blazes when fuels are relatively damp and conditions are cool and humid, allowing for fires that reduce the forest canopy without destroying every standing tree and living creature. Managed fire is basically letting nature run its course. Wildfires would be allowed to burn in unpopulated areas, ideally when weather conditions aren't excessively hot and dry. The U.S. Forest Service is increasingly convinced of the wisdom of this approach. It recently inaugurated new management plans for three of California's national forests, approving managed fire for 50 percent of their acreages.
Thompson and UC Berkeley professor of environmental science, policy and management Scott Stephens are working on a project in Illilouette Creek basin in Yosemite National Park that seems to confirm the healing properties of fire.
“The National Park Service backed off fire suppression and began using managed fire in the basin in 1973,” says Thompson. “Scott and I are seeing strong evidence for increased plant diversity in the basin. There's much more meadowland and scrubland, and the resulting patchiness across the landscape reduces the risk for catastrophic wildfire. We're also seeing greater diversity in water conditions. There are more areas with persistently wetter soils than were recorded under the old completely forested state. We're now trying to determine whether these changes are increasing run-off from Illilouette Creek into the Merced River. “
- Author: Jeannette Warnert
Reprinted from the UCANR news blog
In the small, forested Shasta County community of Shingletown, fuel breaks were successful in limiting the destruction of the 2014 Eiler Fire, reported Jeremy Linder on KRCR TV in Northern California. Linder's story centered on a tour for fire agency representatives presented by UC Agriculture and Natural Resources forestry experts.
UC ANR Cooperative Extension hosted the tour to bring together the different agencies that can collaborate fighting fires, managing forests and building and maintaining fuel breaks to arrest the spread of wildfire.
"Part of the reason (Old Station) didn't burn down is because of all the fuel breaks that the Forest Service had implemented around that general area," said UC ANR Cooperative Extension forestry advisor Ryan DeSantis. "The majority of fires we see are impeded by fuel breaks. They give firefighters time and safer places to fight fires."
Tour participants also discussed maintenance of current fuel breaks, both with and without herbicides. One issue is lack of funding.
"It's good to have everyone come to the table, all the different organizations all the different agencies and get together to discuss what the issues are and how to get through them," DeSantis said.
- Author: Monique Garcia Gunther
Reposted from the UCANR Green Blog
Many forest areas burned by wildfires this year are now facing a new threat – erosion. A UC Agriculture and Natural Resources expert says there are steps landowners can take to reduce the risk of losing soil and polluting waterways when rain falls.
“The loosened soil and ash can move quickly under proper storm conditions,” said Greg Giusti, a UC ANR Cooperative Extension forestry advisor. “Property owners should take immediate action.”
A longstanding practice in the West has been spreading grass seed after a fire, however, the seed is slow to germinate and grow during the cold months that follow fire season.
“Seeding is generally ineffective,” Giusti said. “The seed simply moves and erodes with the soil and ash following an initial rain event.”
After losing a home, homeowners may feel the need to clean up their property. However, leaving woody debris, downed trees and limbs will arrest soil movement. Stumps and standing dead trees also help protect the soil.
“The roots are still in the soil and will help hold it in place,” Giusti said. “As long as they don't pose a danger, trees should be left in place.”
Spreading rice straw or weed-free hay on the ground is another way to protect the soil from erosion. Whole bales of hay can be placed in natural drainages to slow water movement and reduce erosion. Straw wattles – long tubes of compressed straw encased in jute or another material – may be laid out across a slope and secured with stakes.
“I suggest landowners focus on areas of their property where they can have the greatest positive effect,” Giusti said. “You can't cover a whole hillside with straw. People can only do what they can do.”