KINGS BEACH, CALIFORNIA--Early results from the largest ever study of wildfire prevention alternatives suggests that prescribed fire is usually cheaper and more ecologically sound than mechanical thinning. If the rest of the study bears this out, it would cast doubt on President George W. Bush's Healthy Forests Initiative, which most experts agree relies on mechanical thinning.
The methods used by the U.S. Forest Service (USFS) and other agencies to suppress forest fires since the 19th century have created a tinderbox of brush and small trees. Foresters have used both mechanical removal and intentional burning to prevent massive conflagrations, but the relative costs and ecological effects of these two practices are unknown. This year's record-breaking fire season prompted President Bush to propose a plan that would emphasize thinning by private timber companies, which almost always use mechanical methods. It would compensate them by allowing the sale of selected large trees, which are valuable but also resistant to fire.
To evaluate the alternatives, entomologist James McIver of the USFS Pacific Northwest Research Station in Seattle, along with dozens of colleagues, compared forest management effects at 13 experimental forests across the United States. The 5-year study is at its midpoint, but McIver reported preliminary results from a site in northeast Oregon at the Sierra Science Symposium here on 8 October. He found that burning created more habitat for insects and woodpeckers than mechanical thinning. And burning cost around $4 per ton of wood removed per acre, whereas thinning cost around $15. Those numbers could differ in other forests, but the basic picture would likely be the same, McIver says.
The continuing study will yield useful information on ecological effects, although not necessarily on fire risk, as it will not study wildfire directly, according to forest scientist Philip Omi of Colorado State University in Fort Collins. But the economic implications are clear to him: Timber companies probably can't do the job because good thinning is not profitable. And bad mechanical thinning is unlikely to prevent fires. "If we don't take out the small trees and leave behind the bigger trees, we're not going to experience the decline in fires that people are expecting with the Healthy Forests Initiative," he says.