With new “megafires” altering our forests, scientists scramble to understand impacts on wildlife while trying to harness fire to benefit both animals and people
Canada lynx (above) are among wildlife species impacted by larger and hotter wildfires across Washington’s Cascade Range, including a 2015 blaze (right) just north of the town of Twisp.
STANDING ATOP A SNOWY MOUNTAIN PASS in northeastern Washington’s Okanogan-Wenatchee National Forest, biologist John Rohrer scans a landscape transformed by wildfire. Charred, dead trees cover ridges and valleys as far as the eye can see. “This used to be core Canada lynx habitat,” says Rohrer, a U.S. Forest Service (USFS) biologist who has tracked the rare cats in these rugged mountains for more than 20 years. “Now it’s not.”
Eleven years ago, the 175,000-acre Tripod Fire burned through this area, consuming the subalpine lodgepole pine and spruce-fir forest that lynx rely on for hunting. The cats prey almost exclusively on snowshoe hares, which avoid severely burned areas lacking green forage and protective cover. No hares, no lynx.
While fire always has been part of this forest ecosystem, wildfires have grown hotter and larger in recent decades, burning a third of lynx habitat in the northeastern Cascades during the past two decades—and reducing the region’s carrying capacity for female lynx to 27, down from 43 in 1996.
The fires are casting doubt on the future of Canada lynx in the Cascades. Nationwide, the cat is listed as threatened under the U.S. Endangered Species Act, and last year, the Washington Department of Fish and Wildlife changed its designation from threatened to endangered, citing “the loss and fragmentation of habitat as a result of wildfires” as a top threat to survival.
Lynx are hardly the only animals feeling the heat. From mountain lions to moose, wildlife species across the West—and beyond—are confronting increasingly larger and hotter wildfires. Nationwide, a record 10.1 million acres burned in 2015, and the number of “megafires”—those that burn more than 100,000 acres—is on the rise.
According to a 2015 USFS report, the United States loses twice as many acres to fire as it did three decades ago, and that acreage may double or triple by midcentury. The six worst fire seasons recorded since 1960 occurred during the past 15 years, the report adds. While large wildfires are not new—conflagrations of more than a million acres were reported in the late 1800s—their increasing frequency is. Before 1995, an average of one or fewer megafires broke out annually in the United States. Between 2005 and 2014, that number had jumped to nearly 10 a year.
Megafires are primarily a problem in arid western forests, but the danger is also rising in the East. Last November, an inferno dubbed the Chimney Tops 2 Fire (right) broke out in Great Smoky Mountains National Park and rapidly spread to more than 17,000 acres, killing 14 people and destroying more than 2,000 homes and 53 commercial buildings in and around Gatlinburg, Tennessee. Across the Southeast, fires burned more than 150,000 acres during fall 2016.
Today’s wildfires can be so severe that they permanently destroy forests by sterilizing soils, killing seed sources and enabling invasive species such as cheatgrass to move in. “There will be areas out West where we may never see forests come back,” says Bruce Stein, the National Wildlife Federation’s associate vice president for conservation science.
Stein blames megafires on two major forces. The first is “decades of fire suppression that have left many forests seriously overgrown and ripe for major fires.” For nearly a century, USFS and other agencies fought aggressively to extinguish every single fire—based on an assumption that fire is always damaging and destroys valuable timber and habitat. The result is that many forests are now choked with fuel: dense stands of tightly spaced trees and forest floors littered with deep layers of needles and other flammable organic matter. Historically, frequent, low-intensity fires burned off these fuels and thinned out thick stands of young trees.
The second force, Stein says, is climate change. According to a Brookings Institution report, higher temperatures, shorter winters, early springs and reduced snowpack have lengthened the U.S. fire season by 40 to 80 days since 1970. USFS reports that in some regions, the fire season now lasts 300 days per year. More frequent and longer droughts—which spawn hotter, drier and windier summers—also have made forests more vulnerable to large and severe fires.
In addition, climate change has spawned outbreaks of tree-killing insects. During the past several decades, mountain pine and other bark beetles have ravaged millions of acres of conifer forests from the Southwest to Alaska. Though these insects are native, they have become more destructive as milder winters have extended their breeding and feeding seasons. Drought-stressed trees, meanwhile, are less resistant to beetles. The insects have left in their wake large areas of woodlands filled with dead, dried-out trees and forest floors covered with dry conifer needles and branches ripe for ignition. Combined with fire suppression, these myriad consequences of climate change “make it much more likely that when a wildfire does break out, it will explode into a truly extreme event,” Stein says.
It can be difficult to generalize about the impact of fire on wildlife because each blaze and ecosystem varies. For example, woodpeckers that inhabit cavities in standing dead trees and eat insects that live in deadwood benefit from fires that create new habitat—unless the fire is so fierce the forest never grows back. Other species requiring dense forest canopy, such as spotted owls, can decline or disappear following a large fire.
Because megafires differ fundamentally from smaller burns wildlife faced in the past, scientists are scrambling to find out how they affect different species. In Southern California, for example, researchers hypothesize that increasingly frequent fires will suppress mountain lion populations by converting native scrublands, which the cats prefer for hunting and resting, to open, non-native grasslands, says San Diego State University biologist Megan Jennings, who analyzed data on the movements of 44 lions in the state’s Peninsular Range. More frequent fires, often human-caused, are combining with urban and suburban expansion to degrade and diminish habitat, “further endangering the persistence of healthy puma populations in southern California,” says a study Jennings published last year in The Journal of Wildlife Management.
Sage-grouse also are suffering from increasingly large wildfires sweeping through the western sagebrush steppe the birds rely on. Here fire danger is on the rise due in part to the spread of highly flammable, invasive cheatgrass. Once an area burns, a negative feedback loop means even more cheatgrass—which grows quickly—leading to more fires and less grouse habitat.
In Washington’s Cascades, on the other hand, Rohrer reports that moose seem to have benefited from larger fires, which have led to an increase in the willows and other deciduous trees the herbivores feed on. “Twenty years ago, we hardly ever saw moose here,” Rohrer says. “Now we get them wandering into town.”
Though they may yield winners as well as losers in the short term, “on balance, megafires are very bad for wildlife,” Stein says. Unlike traditional, low-intensity fires that leave behind a patchwork of habitats, today’s hotter and larger flames are contributing to landscape simplification. By contrast, biodiversity is usually highest in landscapes that are complex—featuring a variety of habitat types, from open grassy areas and scrublands to forests of different age classes. “Even when a forest comes back following a megafire,” Stein says, “you end up with a uniform habitat rather than the mosaic that benefits most wildlife species.”
As the flames grow higher, the cost to U.S. taxpayers is also mounting. In 2015, the federal government spent a record $2.1 billion fighting fires. (Prior to 2000, the government’s firefighting tab had never topped $1 billion, but since then has exceeded that figure 13 times.) USFS bears most of this cost. Today, firefighting consumes more than half of the service’s budget—compared with just 16 percent in 1995—and by 2025, USFS officials estimate that figure could be nearly 70 percent.
Conservationists say this increased spending has hampered the service’s role as steward of our national forests. “Money is being drained from other important programs, including wildlife management, watershed protection, endangered species monitoring” and other initiatives critical to conservation, says Mike Leahy, NWF’s senior manager for public lands conservation.
To reduce the risk of megafires, scientists and land managers recommend reintroducing low-intensity fire to public lands using “prescribed burns”—fires set during favorable weather with firefighters on hand to contain the flames—that would burn off smaller trees, shrubs and flammable organic matter on the forest floor. Forest ecologists also suggest thinning out overcrowded woodlands by cutting small-diameter trees and allowing larger ones to grow. This kind of “targeted, collaborative forest and fuel management may be the best opportunity to utilize limited funding to actively restore forests,” says Brian Kurzel, director of NWF’s Rocky Mountain Regional Center.
In Arizona, one such project, the Four Forest Restoration Initiative (4FRI), already is underway. Spanning 2.4 million acres across four adjacent national forests, the project—a collaboration among state, federal and local authorities along with conservation organizations—is treating up to 50,000 acres a year with prescribed burns, thinning and “managed wildfires” (natural fires allowed to burn under controlled conditions).
Historically, these ponderosa pine forests experienced low-intensity fires every few years, which kept tree densities to about 25 per acre and prevented huge fires. “Some of these stands now have densities of a thousand trees per acre— 40-year-old trees that are a scrawny 5 inches in diameter,” says Tom Mackin, past president of NWF affiliate the Arizona Wildlife Federation and that group’s point person for the 4FRI. The initiative’s goal is to save human lives and property as well as benefit wildlife—including elk, mule deer, pronghorn, black bear and wild turkey—by returning the forests to conditions that existed prior to fire suppression, when fewer but larger trees provided an open, parklike ecosystem with grasses, shrubs and forbs that are food for many animal species.
In Washington’s Cascades, Rohrer and his colleagues hope a similar ecosystem transformation will take place. During a five-hour snowmobile tour through the Tripod burn zone last winter, they were elated to discover a handful of snowshoe hare tracks. While most hare habitat remains burned out, a few small stands of trees have begun to regrow, providing green cover and forage. “This is good hare habitat,” said Rohrer, examining a patch of young conifers surrounded by standing deadwood.
Still, he and other scientists say it could take 20 to 40 years before these trees grow large enough to provide suitable lynx habitat. Whether or not the cats rebound in coming years will be dictated by flames. “If we want lynx to recover here,” Rohrer says, “we can’t have any more big fires.”
Fighting “Fire Borrowing”
Unlike other natural disasters such as hurricanes and tornadoes, wildfires on public lands receive no dedicated funding within the federal budget. To control the mounting number of destructive “megafires” across the country, federal agencies, particularly the U.S. Forest Service, must take money away from other critical programs such as wildlife conservation and forest restoration. Seeking to end this practice, the National Wildlife Federation passed a resolution at its 2016 annual meeting requesting that the U.S. Congress and president do away with “fire borrowing” by creating a dedicated fund to battle wildfires.
Paul Tolmé wrote about the U.S. biodiversity crisis in the February–March 2017 issue.
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