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Yellowstone a Study in Vital Role of Wildfires

Ecology: Scientists say concern over short-term damage ignores rebirth that occurs in forests.


YELLOWSTONE NATIONAL PARK, Wyo. — For more than 250 years, the three-toed woodpecker barely eked out an existence in the high forests here in the Rockies. 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.

Then something auspicious happened, giving the little woodpecker a break. In 1988, wildfires roared through 750,000 acres of Yellowstone, charring acre after acre of the old forest, 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.

"All those dead trees are bug factories, wonderful for him," said John Varley, pointing to a steep ridge once covered by old-growth lodgepole pines and conifers. Today, the mountainside is prickly with what look like towering black chopsticks. It's the woodpeckers' happy new home.

"In a fire, even a big one, for every loser, there is a winner," said Varley, director of the Yellowstone Center for Resources.

In this summer of massive wildfires throughout the West, Yellowstone offers a compelling lesson in fire's quid pro quo. A forest destroyed is also a forest made over: It becomes more efficient, safer and often more diverse.

Rather than land lying fallow after a fire, other plants rush in to fill the vacuum. After a huge burn, forests are all but fireproof, and the absence of long-established trees opens the forest to new species of plants and healthier versions of their own kind. Animals adapt in similar ways. Like the plants that have always existed in small numbers in the Yellowstone ecosystem, some animals bide their time until conditions are right, then rapidly increase after a big fire.

Since the fires, Yellowstone has become a living laboratory for fire ecologists, who in more than 400 research projects have charted, measured and mapped the massive burn area to calculate the fires' handiwork.

Varley argues that the fires did a fine job of restoring balance to the park. Despite the national hysteria following the park's "let it burn" policy, Yellowstone today shows no signs of devastation. For that, Varley compliments nature and its hardheaded resolve to impose balance on its ecosystems.

Varley walked the park's backcountry to illustrate that point. He paused in a broad green swale, tucked partway up a ridge. His black boots stood ankle deep in a thick carpet of healthy plants and a young 11-foot Douglas fir dwarfed his 6-foot frame.

"Golly, it doesn't look devastated," the scientist wisecracked, gesturing to the vast tract of national parkland before him that exploded in fire on the night of Sept. 10, 1988. That blaze was the last of several major wildfires that rendered the nation's oldest national park an "ecological disaster," as media reports called it at the time.

But destruction, in Varley's experience, is in the eye of the beholder. Where many see this summer's huge wildfires in Colorado and Arizona as, invariably, "devastating," Varley and other scientists know fire for what it is, an integral actor in nature's grand design for survival.

Most plants and animals here have evolved to survive fire. Some even fare better after a fire. The dominant tree in Yellowstone, the lodgepole pine, stores its seeds in a resin-encased cone. Intense fires cause the resin to melt, 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.

Even the lodgepole's seeds are fire-smart: The black seeds spill onto the charcoal and ash and are camouflaged from hungry birds.

Quaking aspen, rarely seen in the park and unable to compete for space with the conifers, are now thriving in leafy green swaths. The aspens' vast root systems are deep and protected from a fire's heat, allowing them to capitalize on the open space provided by the burn.

When a fire takes down tree crowns, it creates more sunlight on the forest floor. Plants that had lain quietly in seed beds beneath the soil opportunistically spring up after burns, responding to newfound light or sensing a change in environment. Everywhere after Western fires, brilliant red fireweed plants abound.

"I 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," said Don Despain, a former research biologist at Yellowstone.

"There's a lot more to forests than trees. They may be gone, but everything else sprouts like mad," said Despain, now with the U.S. Geological Survey in Bozeman, Mont. "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."

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