WILDFIRE! - Yellowstone National Park fires show natural cycle at work

Animals, Fall, 2001 by Deborah Knight

With flames roaring in Yellowstone National Park and elsewhere in the West, a look at how nature copes with forest fires may be surprisingly reassuring.

"YELLOWSTONE DESTROYED," headlines and certain western politicians screamed during the summer of 1988. Fires raced through the park, at times with the roar of a freight train. Oddly, the animals didn't seem to get the news.

As the fires burned around them, elk often gathered in the meadows, chewed their cuds, or rested; only a few even bothered to stare at the flames and smoke. Grizzly bears dug roots in the meadows as the surrounding forests blazed.

That winter much of Yellowstone was a study in black and white: vistas of charred trees standing in the snow. It reflected the human view of all fires as forces of death and destruction. But for the animals, life was more complicated.

Of 30,000 elk in the park, only 246 are known to have died in the fires, most of them in one group that was trapped and suffocated. Of greater import to the elk was the drought that had fed the fires. With forage poor all summer, they found less nourishment and entered the winter with less of a hedge. Some of the forage in their winter range had burned. Then came a strike more deadly than lightning, a cold snap that pushed temperatures below zero for days on end. The elk dropped, especially the older males; perhaps 5,000 died.

But come April, when the lethargic grizzly bears emerged from hibernation, they found a banquet spread before them. They needed only to amble from one meal to the next. The surviving elk meanwhile found their own banquet of new growth, and their herds, pruned of the oldest and weakest members, rebounded. A hillside that had resembled the bottom of a barbecue pit seemed to lose its mind to color: it became a sea of green swept by successive waves of wildflowers, first pink, then yellow and white, then purple and yellow. A kind of geranium flowered that had never flowered before, so park biologists were finally able to identify it. It has never flowered since.

Predictions that tourists would shun the disaster area proved wrong. Curiosity or habit drew people to the park, as it always had. Some thought it hideous and sad, some found it fascinating.

Fire is like an organism: it is born, grows, has an adolescence, declines, and dies. It must consume fuel to live. And in much of the western United States, it has inhabited the landscape since the last ice age. Fire and climate, plants and animals have all played their roles in a long-running play.

In some places, fire naturally licked through the landscape every few years, skimmed off the undergrowth, but left many of the trees, especially the oldsters, such as the thick-skinned, yellow-barked ponderosa pines known as "yellowbellies." Without understory competition, these stately trees stood in widely spaced, parklike elegance while at their feet elk and deer browsed the bright green grass newly nourished by the ash.

At higher elevations, in places with poor soil, lodgepole pines thrived in their own manner: in thick, even-aged stands that allowed little light to filter down to potential competition on the ground. They shed their lower branches as they grew, leaving nothing flammable between the tinder on the forest floor and the canopy of needles, so fire on the ground found little to nourish its growth and soon expired. Only after two or three hundred years, when the slow-growing lodgepoles reached their scrawny maturity and the shade-tolerant Engelmann spruce and subalpine fir had grown up amid them, did that crucial ground-to-crown fuel source exist. Then one year or another, when everything was exceptionally dry and the winds exceptionally strong, one of the thousands of lightning bolts that strike western forests every summer would find a meal and grow. With a thick canopy of needles stretching for miles, the fire would feast in a roaring, raging storm of heat blowing through at a rate of 25 seconds per tree and traveling sometimes for days until rain or snow put it down. This is what happened in the summer of 1988 at Yellowstone National Park.

Only recently have modern humans come to see fire as part of the landscape, as a shaper and maker of life. Rather we have seen it as sowing only death and ugliness, striking terror in Bambi and tears in Smokey Bear. But in the real world it sows also life. It unlocks the seeds from lodgepole pine cones, which are sealed with a resin that melts only when heated. It prepares a feast of dead trees for insects, which themselves become a part of the feast as woodpeckers join the influx to a newly burned site. As the woodpeckers excavate homes in the trees, mountain bluebirds follow to nest in the cavities and to hunt in the open areas, where they snatch insects from the air. Hawks circle above in search of mice, chipmunks, voles, and rabbits, which have less cover in which to hide. The ash provides a shot of fertilizer to the soil, and delicate new shoots of plants and grasses pop up and thrive in the increased sunlight. The lodgepole seeds germinate, sometimes hundreds of thousands to the acre, and within a few years the young trees stand in thick carpets, carrying on a cycle that will likely play itself out in another conflagration hundreds of years from now.