The miracle of recovery: though the ecological legacy of the Yellowstone wildfires is a mixed bag for some species, the forest's remarkable recovery shows how the news media overstated the fire's impact. (Environment).
Consider, for instance, the aftermath of forest fires. During most of the last century (until the early 1970s), our federal fire-fighting bureaucracy deemed such fires so inherently destructive that they required prompt, complete suppression from the first spark. Similarly, for most Americans steeped in Smokey the Bear's "Only you can prevent forest fires!" mantra, the very thought that forest fires might have a positive side seemed preposterous. Yet they do, as all but the most fanatical devotees of the squelch-'em-all strategy now admit in the wake of recent record-breaking fire seasons.
The 1988 wildfires in and around Yellowstone National Park in Wyoming provide an especially revealing glimpse of the intricate miracle of post-fire recovery, since sufficient time has elapsed to gather and analyze meaningful data about the environmental impact of the conflagrations that consumed 1.4 million acres of Greater Yellowstone (a loosely defined area of about 10 million acres), including 739,000 of the park's 2.2 million acres. Some 25,000 personnel were mustered to fight the blazes at a cost of $120 million. More than 10 million gallons of water flowed into the effort before the last fire was officially declared out on November 18, 1988.
Images of the fire dominated the news for weeks, leaving viewers appalled by scenes of animals fleeing as some 250-year-old trees were completely consumed in a mere 15 seconds. Reports on the supposed cataclysm were usually accompanied by one or more "d" words (disaster, defoliation, demise, desolation, destruction, devastation, etc.). Many experts claimed that Yellowstone would never be the same. They were technically correct, but only because the park's ecology would indeed change -- apparently for the better. As Laura Tangley observed in U.S. News & World Report for September 21, 2000, "Today, Yellowstone's meadows and forests are lush with wildflowers and regenerating young trees. More diverse habitat and better food supplies have helped creatures from woodpeckers and hares to elks, lynxes, and bears."
Writing in the Los Angeles Times for July 8th of this year, staff writer Julie Cart recounted her recent interviews with sundry authorities and cited numerous examples confirming Yellowstone's miraculous recovery, and the extent to which its flora and fauna are flourishing. "For more than 250 years the three-toed woodpecker barely eked out an existence in the high forests here in the Rockies," Cart noted. "The 8-inch insect eater never had much more than a tenuous foothold and by the 1980s was on the verge of losing even that, pushed out by hardier birds." But the 1988 wildfires gave the beleaguered creature a new lease on life, "charring acre after acre of the old forest" and "destroying habitat for the bird's competitors. What looked like a disaster for the park's wildlife turned out to be a boon for the woodpecker." John Varley, director of the Yellowstone Center for Resources, told Cart that "all those dead trees are bug factories, wonderful for him." He added: "In a fire, even a big one, for every loser, there is a winner."
Varley recalled, as he pointed to a park meadow lush with plants, that "a few months after the fire, I was right here, walking through 10 inches of ash." Several months later, plants covered 80 percent of the same site, and the year after that it was completely covered with vegetation. "Another way to look at ash," Varley suggested, "is as decomposed nutrients, the building blocks of life."
Cart described the wildfire quid pro quo as a process whereby a "forest destroyed is also a forest made over: It becomes more efficient, safer and often more diverse" as other plants succeed those burned. Indeed, the forests become virtually fireproof for a time, and "the absence of long-established trees opens the forest to new species of plants and healthier versions of their own kind." Animals also adapt as they "bide their time until conditions are right, then rapidly increase after a big fire." Today, there are no signs of the supposed ecological disaster portrayed by so much of the media in 1988.
The lodgepole pine is Yellowstone's dominant tree. Its seeds reside in resin-encased cones. "Intense fires cause the resin to melt," Cart explained, "releasing decades worth of seeds to the forest floor. Because the soil is rich with nutrients deposited by the fire, pine saplings flourish as they would not have before the fire." And since the seeds are black, when they fall onto the charcoal and ash resulting from the fires they "are camouflaged from hungry birds."
Quaking aspen, unable to compete for space with the conifers, were rarely seen in Yellowstone prior to the fires, but "are now thriving in leafy green swaths," since their "vast root systems are deep and protected from a fire's heat, allowing them to capitalize on the open space provided by the burn."
Even the huge "crown" fires that leap high into a forest's canopy contribute to the welfare of some plants, since they "create more sunlight on the forest floor. Plants that had lain quietly in seed beds beneath the soil opportunistically spring up after bums, responding to newfound light or sensing a change in environment. Everywhere after Western fires, brilliant red fireweed plants abound."
Don Despain, a former Yellowstone research biologist currently with the U.S. Geological Survey in Bozeman, Montana, told Cart that he had "worked at Yellowstone for 14 years before the '88 fires and I'd never seen a Bicknell's geranium, but they flourished after the fires." Despain noted that while many trees may be destroyed in a wildfire's wake, "everything else sprouts like mad. We suspect there is a chemical released after fire that causes flowering plants to take off. There is a nitrogen compound in smoke that stimulates other species to germinate."
Winners and Losers
The loss of habitat for some animals merely means new homes for others. Cart pointed out, for instance, that "moose, elk and pine martens, which thrived in old-growth forests, did not do well in years immediately after the fire. Nor did most nesting birds. But some birds, such as three-toed woodpeckers, tree swallows and mountain bluebirds, prospered. Ground squirrels are back, happy in younger sagebrush that allows the small creatures to hide in and peer over." And according to Yellowstone scientist John Varley, "The deer mouse used to be the dominant animal in these forests. Now it's the red-backed vole's turn. Nature is always seeking balance. Fires make it happen."
The New York Times for April 10,2001, reported that "immediately after the 1988 fires, grasses and forbs [herbs other than grass], which burn on top but regenerate from roots below ground, surged back, stimulated by nitrogen and phosphorus loosed from dead plants. Meadows were filled with the brilliant red bloom of fireweed. And tiny, rare plants like blue-eyed mary and the delicate ground smoke thrived."
Prior to the 1988 fires, according to Times reporter Jim Robbins, "Yellowstone was about 70 percent old growth or mature forest, and the fires burned off about a third of that." Moose were among the losers, since in winter they feed on the new growth of fir and spruce trees that spring up in old growth areas. Pine martens also took a hit, since they favor tunnels created by deadfall, and snow in old-growth areas, to both hide from predators and stalk prey.
The list of winners, on the other hand, "included hawks, which prospered even as the fire raged" from a virtual buffet of rodents scurrying to find new cover. Also, "nesting birds, including those who make their homes in the cavities of trees, flourish immediately and in the first few decades after a fire," since boring beetles and other insects "feast on dead trees, then become the feast as woodpeckers, mountain bluebirds and tree swallows swarm to burned areas."
Dead trees that topple also alter the forest-floor species composition, "providing cover for snowshoe hare, voles and deer mice," which in turn comprise "a fully stocked grocery for a variety of predators. Biologists expect to see an increase in the number of lynx, for example, which feed on hare."
In the short run, the fires may have had a negative impact on sections of streams and rivers, but Dr. Wayne Minshall, a professor of ecology at Idaho State University who has studied streams for 35 years, told Robbins that "two to 15 years after the fire, conditions recover and often get better than they were before the fire." Ash, burned trees, and mud flow "create a deadly slurry that flows into a stream and can kill fish, move channels and widen the stream by a factor of 10 to 100 times." But once the burned material has washed out, "the stream starts to recover and often becomes more heterogeneous." For example, "With the [tree] canopy gone, sunlight causes algae to grow, which feeds insects. More woody debris in the stream increases pools where fish can spawn. Nutrients unlocked by the fire stimulate the growth of riparian [i.e., stream-bank] vegetation, which improves insect habitat and food. As the size and number of insects increase, so do the size and number of fish."
Mary Ann Franke of the Yellowstone Center for Resources wrote in Yellowstone in the Afterglow: Lessons from the Fires (2000) that "instead of fleeing in a Bambistyle panic, Yellowstone's wildlife generally went about their activities as usual and lost few lives to the smoke or flames." While "reports of Yellowstone's death in 1988 were greatly exaggerated, so were the announcements of its 'rebirth,'" since "Yellowstone did not need to be reborn because it had not died. Its ecological processes have continued to function without interruption, producing year after year of new plant growth and new generations of wildlife." Franke pointed out that, to survive, "plants need minerals such as nitrogen, phosphorus, potassium, magnesium, and calcium -- nutrients that are usually absorbed by the plant's roots from the soil." In areas such as Yellowstone "fire is often the most efficient agent for recycling nutrients back into the soil."
Franke noted that "the only animals for which there is evidence of a population decline as a result of the fires are moose and snails." While "extensive fires cause habitat alterations and may displace animals from their customary ranges," such fires "do not kill significant numbers of wildlife." In Yellowstone, except under "the most extreme conditions of fast-moving fire fronts," most animals "appeared in-different to the flames and, like human grazers at a 1950s cocktail party, many continued their foraging activities even in thick smoke."
Grizzlies survived the fires with negligible negative impact on their numbers. Franke stated that in 1994 (for the first time), and again in 1998 and 1999. the grizzly population in Greater Yellowstone "met all three of the targets for delisting as an endangered [threatened] species." It was not delisted, however, because the pertinent federal and state agencies could not agree on a strategy to secure the bear's habitat and monitor its population.
Franke noted that small mammals are more likely to die as a direct result of wildland fires than are large ones. But here again, benefits to other species tend to balance the scales. "Coyotes, foxes, and weasels benefitted from the loss of cover available to their prey and from scavenging on fire-killed carrion," and "some appeared to be attracted to fires, presumably looking for animals driven from their homes. With few islands of grass in which to hide, mice, voles, chipmunks, and squirrels became easy targets in areas of ground fire." And should the number of small mammals temporarily decline as predators multiply in the immediate wake of a fire, "the increased number of predators would soon face a food shortage themselves, continuing the ongoing adjustment in the predator-prey ratio."
Franke wrote that "many birds received at least short-term benefits from the fires, including some osprey and other raptors." Yellowstone ornithologist Terry McEneaney believes, according to Franke, that "they may have been alerted by the columns of smoke that signaled places where rodents were fleeing to escape the heat and flames, only to find themselves swept off the ground by some large bird." Osprey are mostly fish-eaters, but "McEneaney saw one carrying a red squirrel in its talons. Although ferruginous hawks [North America's largest] are rarely seen in the park," one day "McEneaney saw more than 40 ... feeding on displaced voles and pocket gophers."
McEneaney conducted a number of bird censuses that found mixed results. As summarized by Franke, he "attributed the decline in bald eagle fledglings in the park from 12 in 1988 to 3 in 1989 to be 'due to unstable nesting trees as a result of the wildfires,' yet the fledgling count reached a record 17 in 1993 and has remained above pre-fire levels in subsequent years." McEneaney expected that falling trees during the decade after the fire "could result in egg failure, loss of nest sites, or sudden changes in nesting locations," but eventually concluded (in his words) that "these naturally occurring post-fire conditions are unlikely to cause a significant change in the bald eagle population as a whole."
"Over the longer term," Franke contended, "the different intensities and types of burn have increased the diversity of bird habitats, with more open areas for ground nesters and dead stands of trees for cavity dwellers, and abundant insects to be found in decaying trees and litter."
Even the park's controversial wolf population, reintroduced in 1995, may be benefitting from the fires, though at the expense of elk. As Franke points out, "a wolf pack's success in bringing down a winter-stressed elk could depend on the wolves' superior maneuvering skills in the deeper snow pack of a forested area that lost its canopy a decade before."
Ecologically speaking, the legacy of the Yellowstone wildfires has been a mix of positive and negative, depending on the species of flora and fauna affected. To date, however, available evidence gives a decided edge to the positive.