Because large wildfires are driven by weather conditions, not fuels buildup, more forest management can’t stop them, and may even exacerbate their intensity, an ecologist told an audience at the Community Library in Ketchum on Wednesday.
George Wuerthner, ecological projects director at the Sausalito-Calif.-based Foundation for Deep Ecology, said episodes of large fires occur naturally and are critical to forest health, recycling nutrients and creating habitat for many species of animals and birds.
Wuerthner’s talk was hosted by the Western Watersheds Project, an environmental organization in Hailey. He is the author of “Wildfire: A Century of Failed Forest Policy.” Through a fast-paced PowerPoint presentation, Wuerthner emphasized the futility of trying to stop large fires by pointing out that only 2 percent of wildfires in the Rockies have been responsible for 96 percent of the acreage burned. He said those fires have all occurred under hot, dry, windy conditions.
“If the conditions are right, you’re not going to stop the fires,” he said. “Wind is the biggest thing. Wind-driven fires have what is called spotting, which is why it’s so hard to stop them.”
Wuerthner pointed out that the Northern Rockies’ “fire decades” have occurred in the early 1900s and from the 1980s to the present, when warm weather and drought predominated.
“We couldn’t put out fires once the weather and climate changed,” he said. “Even the people who used to think that it was mainly a fuels-driven thing have come around to seeing that weather and climate are the most important.”
Wuerthner said lodgepole pine forests typically host high-intensity, “stand-replacement” fires that burn only once every 100 to 300 years, and therefore the past half century of fire suppression cannot be responsible for fuels buildups there. He contended that calls for more forest management are motivated more by economics and politics than by science.
“It’s being promoted by the timber industry and the people in the agencies that depend on cutting timber for their jobs,” he said.
Wuerthner said thinning of forests can make them more flammable in severe weather conditions by drying the understory and removing windbreaks. He said thinning also promotes the growth of small trees, requiring constant maintenance of thinned areas to avoid a flammable understory. He contended that that’s practical only in narrow buffer areas around towns.
Wuerthner said those buffers combined with construction of less-flammable buildings provide the best protection for developed areas. He pointed out that house flammability, not wildland fuels, is the major cause of the spread of fires to residential areas. He said just one house with a flammable roof can endanger a whole neighborhood.
“If your neighbor has a cedar-shake roof, your house may still burn down if there’s a fire, because structure fires burn a lot hotter,” he said.
Wuerthner called the trees killed by fire “biological capital invested in a new forest.” He said two-thirds of forest wildlife species depend on the short-lived habitat created by burned forests. He said even the sediment washed down hillsides benefits stream ecology. He said aquatic species have adapted to more siltation occurring for a few years, but not to the permanent sediment runoff caused by logging roads.
“You have to tolerate the big fires because you’d hardly have any ecological work done at all if you relied on the small fires,” he said.