Study Questions Effectiveness of ‘Controlled Burns’

Conducting “controlled burns” to clear underbrush in grasslands is not the best way to prevent dangerous runaway blazes, according to controversial new research by a government scientist.

Challenging prevailing wisdom, Jon Keeley, an ecologist with the U.S. Geological Survey in Sacramento, and his colleagues found that proven forest fire control techniques aren’t necessary or effective in brushlands.

The research was published recently in the journal Science and based on a review of 90 years of fire history in California.

Overall, the researchers saw no significant change in the average size of fires over the nine decades--nothing to indicate that big fires are getting much bigger or smaller.

Fire officials, however, remain skeptical about Keeley’s conclusions.

“Prescribed burning is the most effective and environmentally acceptable [approach],” said Angeles National Forest Supervisor Michael J. Rogers.

The debate has high stakes in a region where brush fires annually can do millions of dollars in damage.

Keeley’s research conflicts with findings that vigilant firefighting since the early 1900s has led to larger and more damaging brush fires. The theory has been that small fires cleared the buildup of underbrush that fed the larger and more dangerous blazes.

The key to preventing catastrophic blazes, it was thought, was to allow small ones and start “controlled burns.”

“In the ‘70s, it became widely recognized that fire suppression had been very effective in forests, and there began to be widespread concern about the accumulation of fuel,” Keeley said. “And people just transferred the idea to [brush areas].”

In essence, the debate over controlling fires can be reduced to one main question: To burn or not to burn? Traditionally, under a policy called fire suppression, fires were put out as soon as they were detected. Over the last 20 years, most management plans have moved toward controlled burning, where monitored fires are used to reduce an area’s vegetation.

The Orange County Fire Authority is preparing a fire plan that in some cases will recommend that fires be left to burn, provided that they do not pose a threat to people or property.

Managers in Angeles National Forest start small fires. Such approaches are typical of those employed nationwide.

“We’re into ecological management now, integrating fire as part of the vegetation management system,” said Robert Minnich, an ecologist at UC Riverside and a critic of the Keeley study. Minnich wrote a 1983 paper linking traditional fire suppression to an increase in large brush fires.

When Keeley studied the size and frequency of fires in areas of California with shrubs and grasses, he found that fire suppression hadn’t been as successful as was thought.

In contrast to forests, in the brush areas, “we’re not really that effective at stopping [small] fires,” so there isn’t as great a buildup of fuel, he said.

From his point of view, large-scale controlled burning is difficult to do and unlikely to prevent very large fires. Instead, he says, it is more effective to concentrate on a few key firebreaks--maintaining certain areas with no flammable vegetation.

* PRESCRIBED BURN GONE WRONG: Two dozen homes in Trinity County were destroyed by a fire set in an effort to thin brush. A8