For decades, the federal guardian of America's forests has pursued a policy of suppressing wildfires - so effectively that it inadvertently created tinderbox conditions in Western forests.
But after several devastating blazes, similar to the one that recently charred 16,000 acres of the Santa Fe National Forest in New Mexico, the US Forest Service in the 1990s has stepped up testing of another method: fighting fire with fire. Under this preventive approach, fires are set deliberately in an effort to clear out undergrowth, mimicking the effect of naturally occurring fires.
How far to go in implementing this "natural fire policy," however, is hotly contested, marked by long-standing distrust between environmentalists, the timber industry, and federal land-management agencies. Some environmentalists, for instance, accuse federal agencies of using the fire-prevention issue to carry out logging under the guise of thinning out dangerously dense forests.
But there is little disagreement that fire-suppression policies led to the New Mexico fire, creating conditions typical of Western forests. These pine forests have become densely packed: Where tens of trees stood a century ago, hundreds and even thousands now crowd in. Suppression of natural fires meant a huge buildup of pine needles, pine cones, bark, and other flammable materials around the bases of these trees. And a heavy underbrush of bushes and shade-tolerant small trees such as Douglas fir have encroached underneath the tall Ponderosa pines.
"That gives you a ladder of fuel that leads the fire right up into the crowns of the Ponderosa," says John Chambers, assistant director of the Forest Service's fire and aviation management division. Whereas natural fires used to cleanse the forest floor but leave the older and stronger Ponderosa pines intact, now the fires become extremely hot and burn entire stands, as happened in the New Mexico fire. In 1988, a fire in Montana burned 250,000 acres, half of that in one night.
The government's policy of blocking forest fires - and the fires' healthy ecological effects - has distorted the growth of the vast pine forests of the West, explains Mr. Chambers. "Due to the absence of fire, we've got a worsening situation," he says.
The US Forest Service began to recognize this problem in the late 1970s when it altered its fire-suppression doctrine to allow for the use of "prescribed" burns. Beginning in the 1990s, more money and research has been directed toward fighting fire with fire.
"The Forest Service is really pioneering development of a natural fire policy," says Richard Manning, author of numerous books and articles on Western environmental issues. Among the methods being used are removing debris, salvage logging to get rid of dead wood, and thinning out smaller trees.
Forestry experts say the long-standing fire-suppression policy can be traced to two principal culprits: loggers and ranchers. The timber industry was the main force behind the fire-suppression policy, sparked by massive fires in the northern Rockies in 1910 that raised concerns of a timber shortage. Meanwhile, overgrazing removed the grasses that carried the relatively cool natural fires that used to occur every five to 15 years, says John Horning of Forest Guardians, a Southwest-based conservation group.
Prescribed burning, while increasing as a forest management tool, is still small-scale. The Santa Fe National Forest, for example, has carried out only one large-scale prescribed burn of 5,000 acres. From 1984 to 1993, prescribed fires took place at a rate that would burn an acre of Forest Service land only once every 237 years, according to official statistics.
Santa Fe forest officials point a finger at environmentalists who filed suit this year to halt a planned burn and who obtained an injunction blocking any logging in the Southwest to protect habitat of the Mexican spotted owl.
While conservationists support prescribed fires in principle, they are skeptical of the Forest Service and other federal agencies, accusing them of using salvage logging permits to cut down the few remaining old-growth forests.