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Another view: Don't assume that fire is bad for forests

By Chad Hanson
December 15, 2008

Reading Tom Knudson's article about Sierra Nevada fires made me realize how badly some still misunderstand the ecology of fire in forests. The article assumed that today's fires are destructive to forests and wildlife.

The article doesn't report, however, that before early 20th century fire suppression, fires burned far more acreage each year in California's forests than they do now. Even high-severity fire has been reduced relative to its historic extent. Further, while the article cites a flawed study to claim that fires are becoming more severe, this assertion is contradicted by a comprehensive analysis done jointly by the U.S. Geological Survey and the U.S. Forest Service's research branch.

Moreover, the article doesn't mention that current fires are predominantly of low and moderate severity, and incorrectly assumes that high-severity patches (where most or all of the trees are killed) are damaging to native wildlife and forest regeneration.

Natural conifer regeneration is vigorous and abundant after high-severity fire. In addition, high-severity fire areas support the highest biodiversity levels of wildlife species and higher plants compared with other forest habitat types in the western United States.

As one of the nation's top ecologists recently concluded, the "dramatic positive response of so many plant and animal species to severe fire and the absence of such responses to low-severity fire in conifer forests throughout the U.S. West argue strongly against the idea that severe fire is unnatural."

High-severity fire creates important habitat features that are typically absent or in short supply in most forests – habitat elements such as large snags (fire-killed trees) in which woodpeckers create nest cavities, large downed logs in which small mammals live, and patches of native brush and conifer regeneration used as nesting and foraging habitat by many birds and mammals. This post-fire habitat type is called "snag forest habitat," and it is an ecological treasure.

Sadly, countless native species that depend upon this habitat, like the black-backed woodpecker, are imperiled due to fire suppression and post-fire "salvage" logging.

We can effectively protect homes from fire by creating defensible space within 100 feet of structures and using fire-resistant building materials. That's where we should focus our attention and resources.

In remote wildlands, however, it's time to reject the outdated notion that fire "destroys" or "devours" forests, and realize that an ecologically "healthy forest" is one that coexists with fire.

Chad Hanson, a research associate at the University of California, Davis, and director of the John Muir Project, is responding to the Nov. 30 article "Changes feed monster fires."