SACRAMENTO, California – New studies suggest that prescribed fires – small fires set on purpose to remove extra underbrush and dead wood – may not be the best way to reduce the risk of catastrophic wildfires. “Although prescription burning has proven to be a viable means of reducing fire hazard in some forest types, it is not appropriate for the boreal forests of Canada and the chaparral shrublands of southern California,” says Jon Keeley of the U.S. Geological Survey (USGS) in Sequoia-Kings Canyon National Parks, Three Rivers, California. Understanding the natural role of fire in ecosystems is necessary to manage fires to protect human life and property, without damaging the environment. The idea of using prescribed burns to reduce large, intense forest fires throughout the western U.S. came from studies of yellow pine forests in the interior West, such as northern Arizona. These yellow pine forests once had frequent surface fires that resulted in an open canopy mosaic of old and young stands of trees. Fire suppression led to an unnatural buildup of small trees, and dead branches and needles on the forest floor, which then fueled catastrophic crown fires. But although prescribed burning makes sense for these yellow pine forests, the management technique is not warranted everywhere in the West. Prescribed burning fails to reduce crown fires in closed canopy forests and shrublands, where large, intense fires are natural and burn through young and old stands alike, Keeley said. Prescribed burning can have harmful consequences in closed canopy forests and shrublands. For instance, when prescribed burns are more frequent than the natural fire regime, they can outstrip native species’ ability to recover and so lead to local extinctions. The USGS research appears in five papers published in the December issue of the journal “Conservation Biology.” The scientists argue that landscape scale prescribed burning is not an effective means of preventing massive wildfires, and present evidence that limited prescription burns are more cost effective. “One of the most important roles for fire managers of these ecosystems may be educating land planners on the limitations of reducing fire hazards in these natural crown fire ecosystems,” said Keeley.