The Southwest model has also been used to justify thinning and prescribed burns in dry Montana and Idaho forests. But further study by The Wilderness Society's scientists and Dick Hutto, a University of Montana biologist, showed that those forests had a history of less frequent, more severe fires than did Southwestern forests.

Merrill Kaufmann, a retired Forest Service ecologist with the Rocky Mountain Research Station in Fort Collins, Colo., was one of the first to question the ideal of park-like, open forests. In the 1990s, while studying the Pike National Forest in south-central Colorado, he asked agency staffers where they got their forest-treatment information. "All they could come up with was the Southwest model," he says.

Kaufmann soon discovered that the area's old-growth ponderosa pine and Douglas fir forests didn't fit that model, though. Low-severity surface fires and open, park-like stands were not the dominant types over the past 500 years. Instead, the forest had many dense patches of trees that had grown up in areas burned by severe crown fires.

Few fire ecologists -- including those whose work supports the conventional wisdom -- dispute the idea that fire regimes and forest structure vary around the West. Tom Swetnam, who directs the tree-ring research lab at the University of Arizona, writes in an email, "No one that I know is arguing that all forests and all management solutions to fire problems are the same everywhere. … It is quite true that high severity, stand-replacing fires are not abnormal in some forest and shrub types."

Yet while scientists may be clear about which specific forests were park-like and subject to frequent, low-intensity fires, the complexities are often lost on politicians and the mainstream media, who prefer straightforward explanations.

Many news stories about Western wildfires perpetuate the Southwest model. "Historically, natural, smoldering fires thinned the forest floor every 15 to 20 years," a July 19 CBS News story asserts about all Western forests. A July 2 story in New Scientist makes a similar claim.

The 2002 Healthy Forests Initiative also assumes that all Western forests are more overgrown now than they were historically. "Today, the forests and rangelands of the West have become unnaturally dense. … When coupled with seasonal droughts, these unhealthy forests, overloaded with fuels, are vulnerable to unnaturally severe wildfires." The 2009 FLAME Act makes similar assumptions.

Covington himself may have inadvertently contributed to the problem:  Scientific papers with titles like "Helping western forests heal: the prognosis is poor for U.S. forest ecosystems" suggest his research has broad applications for all Western forests. And he says, "There is no 'Southwestern' model. That is horseshit. Everywhere you go, you find ponderosa pine that is open and park-like."

Baker and Williams are not the only researchers who say ponderosa and mixed conifer forests are not all prone to frequent, low-severity fires. Still, other fire ecologists have questioned their methods and data interpretation.

North and Kaufmann both criticized their reliance on and interpretation of the General Land Office surveys. "It's a very scant data set," North says. "The methods used in those papers are not at all appropriate for making the kinds of extrapolations" the team made.

And both Swetnam and Peter Brown, who runs the nonprofit Rocky Mountain Tree-Ring Research lab, questioned how ponderosa pines could regenerate if Baker and Williams are correct about severe fires having scarred Western landscapes for generations. Lodgepole pine seeds need heat to be released from their cones, but ponderosa seeds are destroyed by fire. Baker acknowledges their concerns, calling the regeneration question "a problem area" in fire ecology.

Normally, such critiques play out in scientific journals, but this has been a particularly public controversy, with researchers lashing out at Baker in newspapers. Swetnam told the Associated Press the paper was "deeply flawed in multiple ways, and I have yet to hear any knowledgeable forest or fire ecologist or forest manager say they are convinced by (its) main interpretations."

The passionate reaction is driven by fear that Baker's studies could undermine support for restoration work, according to Greg Aplet, a senior forest scientist at The Wilderness Society. Many researchers and fire managers think immediate action is needed to reduce fuels, and that not nearly enough thinning has been done, especially around communities, where reducing the risk of fire is as much of a priority as restoration. "We gotta get in there and we gotta restore these stands," Brown said, "and to my mind, Baker is just an anchor dragging us backwards."

But so far, Forest Service budget cuts have impacted restoration efforts more than studies, including Baker and Williams', that question the effectiveness of fuel treatments. More and more, the treatments that do occur are based on localized research rather than a blanket application of the Southwest model. A three-year old Forest Service initiative, the Collaborative Forest Landscape Restoration Program, is working on localized studies to influence forest management.

It's important to tailor treatment work to local conditions, says Hutto, the Montana biologist, because the federal government is spending money thinning forests that actually have a long history of dense stands and severe fires. "If they knew severe is natural, there's less justification for that kind of behavior," he says. "I think it's very important to taxpayers to be worried about whether we're going about things in a way that's kind of a waste."