Plenty, say ecologists who study the effects of fire on the landscape.

While the siege of lightning-sparked fires continues to inundate parts of Northern California with hazardously smoky air, the blazes also consumed more than 1,400 square miles of dangerously overgrown forests and oak woodlands – the size of nearly three Lake Tahoe basins – leaving that much less fuel for future, more catastrophic and expensive fires.

Federal land managers in California are retooling their firefighting strategies to capture more of the public safety, economic and environmental benefits of letting wildfires run their natural course without overwhelming the public with smoke and destroying homes.

That's a tough balancing act in the nation's most populous state, which already endures the smoggiest and grittiest air in the country. But in a select few remote national forests, parks and wilderness areas, ecologists say, the federal government has been weaning itself off Smokey Bear's admonitions with measurable success.

"We didn't have any injuries. We didn't burn any houses, and we cleared out 15,000 acres of dense vegetation that hasn't seen fire in decades and, in some places, a century – and that's a good thing," said Brent Skaggs, a U.S. Forest Service fire management officer who let nature take its course under close watch – and tricky weather – in the Clover fire that was recently contained in the Sequoia and Inyo national forests.

Federal officials call it "reintroducing fire" to the landscape. Historically, wildfire smoke filled the Central Valley and draped the mountains flanking much of the summer and fall. Extinguishing the fires became a federal mandate with the creation of the Forest Service at the turn of the 20th century.

The firefighting made it safer to extend development into the woods, but also made for more dangerous forests with the buildup of deadwood that would have otherwise gone up in smoke. As a result, modern blazes recur more frequently. And they often do more damage than good to the flora and fauna – humans included.

Backing off from total fire suppression and letting fire run more of its natural course effectively inoculates the forest from more virulent fires that denude large swaths of the landscape, which in turn invites mudslides.

"We could have suppressed it and had the thing out earlier, Skaggs said of the Clover fire, which was discovered May 31. "But by doing that we would be just prolonging the inevitable. We had an opportunity to manage fire or have it manage us."

The practice, of course, could backfire. A sudden shift in wind direction or unexpected gusts in the unnaturally dense forests could turn such experiments into disasters – plastering communities with smoke or, worse, burning them down.

Fire managers have reduced the chances of a hands-off fire running awry by limiting the practice to the remote backcountry of the central Sierra and the desolate northern corners of the state.

Namely: Portions of the Mendocino, Klamath and Shasta-Trinity national forests that encompassed large wilderness areas; Lassen National Park and the neighboring Lava Beds National Monument and Modoc National Forest; and Yosemite and Sequoia-Kings Canyon national parks and surrounding Stanislaus and Sequoia national forests. Managers of these forests have plans in place for using the let-it-burn approach, known in firefighting parlance as "wildfire use" or "appropriate management response."

Even then, the practice cannot be used without a series of approvals up the Forest Service line of command, from the ranger on the ground to the brass at headquarters in Washington, D.C.

Beyond that, forest officials in many cases need the permission of local air pollution control districts.

The Forest Service had a tough time getting the cooperation of pollution regulators when it began "wildfire use" about five years ago, said Trent Procter, air quality program manager for the agency's Pacific Southwest region, which includes California.

Working against the agency were earlier "prescribed burns" – deliberately set to thin out fire-prone thickets – that went awry at Lake Tahoe and the Stanislaus forest.

Relations have since improved. "They realize that in the absence of (natural burns), we'll end up with more catastrophic wildfires like those we have now, where the smoke will be worse, Procter said.

For its part, the Forest Service recently added at least a dozen portable air pollution samplers to the state Air Resources Board's network for monitoring the smoke levels, which reached the hazardous level Thursday in the Trinity County seat of Weaverville, said Jeff Cook, an emergency response coordinator with the air board.