- 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.”