Wildfires: Some ecologists are yielding to nature's fire logic

With wildfires raging out of control in 13 Western states, Rex Wahl has seen enough. Like a peace-loving homesteader who finally reaches for his six-shooter, the influential environmentalist has unholstered his chain saw.

Wahl is ready to cut down trees to save the forest.

The executive director of Forest Guardians, an activist group based in Santa Fe, N.M., had long opposed the removal of any tree for profit or for managing nature.

Then he watched helplessly from his yard as a small, planned fire raged out of control at nearby Los Alamos in May. It charred 48,000 acres, destroyed 200 homes and caused an estimated $1 billion in damage.

''Wildfires are getting bigger, burning hotter, and the effects are more devastating,'' Wahl said. ''It's clear we'll have to take mechanical steps like thinning before we can use fire to restore these forests to a more natural regime.''

As of Thursday, 85 major wildfires were burning from Washington to Texas. More than 4 million acres have been blackened this summer, and eight firefighters have been killed. It is perhaps the worst fire season in the past 50 years, rivaling 1988 and the great Yellowstone blaze.

The wildfires are being blamed in part on a century of conflicting land management policies that researchers say have misunderstood or ignored fire's purpose in nature:

- A longtime practice of putting out all fires instead of letting them burn has allowed flammable brush, dead wood and other fuel to accumulate waist-deep in some forests.

- Ranchers have let cattle overgraze meadows that could otherwise make fires burn slow and cool.

- Commercial loggers have removed many large, fire-resistant trees. At the same time, environmental restrictions in many areas have prevented timber companies from thinning out overgrown forests and removing dead wood.

- Some homeowners as well as environmentalists who are worried about endangered species have opposed ''controlled burns'' that could remove the brush.

As a result of the devastating wildfires of recent years, however, some environmentalists are rethinking their opposition to cutting trees. Among them is Forest Guardians, which had been one of the most vocal ''zero-cut'' groups.

Wahl, a biologist, suggested that old environmental dogmas must be abandoned. He is not embracing clear-cutting. Unlike loggers, he wants to save the big trees that are fire-resistant and readily seed new growth.

''Judicious cutting of smaller trees is what's needed,'' he said.

Other environmental groups have endorsed the concept of forest thinning but have been unable to come to terms with the government on the details.

''I'm still waiting to see a thinning project where they will take only the trees that are causing the problem,'' said Sharon Galbreath, a Sierra Club spokeswoman in Flagstaff, Ariz. ''They want to take large trees, too.''

Forest industry officials said they doubt activist groups have substantially changed their ''zero-cut'' attitude toward logging, or would embrace a forest thinning program that the industry considers realistic.

Cutting only the smallest-diameter trees probably would not markedly improve forest health, they argued. They recommend cutting some larger trees to allow more sunlight and nutrients to reach the remaining growth. Those larger trees would be used in wood products, they said.

''If you're going to do commercial thinning, you'll need to take trees out of there to make products,'' said Butch Bernhardt of the Western Wood Products Association in Portland, Ore. ''That's the incentive.''

Wahl's conversion reflects the crisis facing the West's sickly forests.

A century ago, before federal agencies adopted a military approach to suppressing firs, healthy conifer forests sprouted 25 to 70 mature trees per acre. Lush meadows filled the gaps.

Little fires swept through the grass and seedlings, but thick bark protected the large trees for hundreds of years. An added bonus: The fires' heat melted the resins in fallen cones, releasing their seeds.

Lightning ignited many of these fires. But tree ring records and other sources suggest many fires were set by Indians to flush game and encourage plant regrowth.

''Fire is a land management tool that they learned to use well,'' said Don Despain, an ecologist for the U.S. Geological Survey in Bozeman, Mont.

Today's forests stand in cadaverous contrast. After a century of fire suppression, as many as 850 spindly trees per acre clog the same forests. More than half stand dead, starved for sunlight and strangled by insects that bore into them.

On the ground, overgrazing by cows has compacted the soil and stripped away the green grass. Brush and dead limbs have piled up.

In a dry year, a careless camper, a hot muffler or lightning can spark a catastrophe.

In 1988, the Yellowstone fires were out of control within 20 minutes and burned for four months. Temperatures reached 2,000 degrees, melting steel culverts and glass bottles.

''All of those smaller understory trees allow the fire to jump into the crown of the forest,'' Wahl said. ''If you get wind, it's hard to save any of them.''

What happens after a blowup depends on the landscape and the weather.

Twelve summers after the Yellowstone blaze, surveys suggest plant diversity in the burned areas might be 10 times higher than pre-fire estimates.

But in other locations, the heat from large wildfires has penetrated nearly a foot into the soil, roasting roots and seeds.

The heat also caramelizes sap and resins into a waxy layer known as hydrophobic soil. Rain beads up and rolls off the blackened surface. Plants cannot sprout, and a single thunderstorm can flush away topsoil that took 2,000 years to accumulate. The sediment, in turn, clogs streams.

After a fire in 1989, Oregon's Grande Ronde River - including spawning grounds for the endangered spring Chinook salmon - remained dead for 35 miles until the mid-1990s.

Arizona State University biologist Steven Pyne and other experts recommend fundamental changes in the nation's wildfire policy: Mechanically thin forests and remove dead litter. Stop cattle grazing. Tighten zoning and building codes. Combine fire suppression and prescribed burning in a single program.

''I don't see many people who like the forests as they exist today,'' Pyne said. ''They are not the forests that people want.''

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On the Net:

National Interagency Fire Center: http://www.nifc.gov

Forest Guardians: www.fguardians.org

Northwest Forestry Association: www.nwforestry.org/