Heavy commercial logging, insufficient brush clearance and a policy of suppressing smaller wildfires are behind the devastating blazes raging in six states across the US, says forest fire experts. And, they say, the problem will get worse.
Eighteen large forest fires are burning in Arizona, Colorado, New Mexico, Utah, Nevada and Wyoming. They are consuming well over twice the average acreage for this time of year. Already, nearly 930,000 hectares have been burned in this year’s fire season and officials say 29 million hectares, about 40 per cent of all Forest Service land, are at risk of severe fires in coming years.
The blaze in Arizona, which is currently 80 kilometres across, is the biggest in the state’s history. It has already burnt more than 1,500 square kilometres of forest and could spread to more than half a million acres and burn for several weeks, Forest Service officials say. President Bush is expected to visit some of the 25,000 Arizona people evacuated from their threatened homes on Tuesday.
“Fire has always been a natural part of these ecosystems but over the last century we have been suppressing fires and so allowing highly flammable underbrush and small trees to over-populate the forests. We need a thoughtful, science-based strategy to counter this,” Mike Dombeck, professor of Global Environment Wildlife at the University of Wisconsin and former head of the US Forest Service, told New Scientist.
“The recent increase in the number and severity of forest fires is directly attributable to the fact that we have not carried out enough controlled fires and have not been adequately ‘thinning’ the forest, by cutting down brush and small trees.”
“Commercial logging of large, fire-resistant trees is exacerbating the problem, because it encourages growth of underbrush, making fires much hotter, more intense and faster spreading,” Dombeck adds.
The increase in logging, and the reduction in forest thinning and the setting controlled fires to burn off easily flammable brush are creating ever more ideal conditions for devastating wildfires in the US, experts say.
Controlled fires and forest thinning are controversial techniques. They are used to a limited extent in the US, and in other at-risk countries, such as Australia. These practices must now be stepped up, Dombeck says. But on Sunday, the head of the US Forest Service said the Bush administration has no plans to change fire policy.
Controlled fires and forest thinning are opposed by some environmental organizations, though other groups are in favour.
Ed Brunsen, fire education director at The Nature Conservancy, based in Virginia, US, says: “Some organisations feel there should be no tree removal whatsoever and that controlled fires are a bad thing, especially since some have got out of control and caused severe damage. But there is a big difference between commercial logging and brush clearance, which can be a very important landscape management tool.
“These fires are going to burn anyway whether controlled or uncontrolled and at the moment they are having a very negative and destructive impact on the forest itself, because of their intensity and frequency – rather than the positive ecological effect that a controlled fire can have,” Brunsen told New Scientist.
Exceptionally dry weather this year has also contributed to the fires. “Given that it’s only June, we could have an exceedingly challenging year ahead,” Dombeck said.