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Some scientists say it might be better to let modest fires burn rather than rush to extinguish them, to protect long-term forest health

PHOTO BY GARRETT MEIGS, COURTESY OF OREGON STATE UNIVERSITY - About half the trees were killed in this Central Oregon stand during the 2003 B&B Complex fire. But a high number of trees survived and vegetation rapidly recovered, as seen from this 2007 image. On Labor Day weekend, the Eagle Creek fire began burning its way through 49,000 acres of forest in the Columbia River Gorge. Although the fire torched a remote area, it threatened urban dwellers 50 miles away as it discharged thick clouds of smoke toward Portland that lingered for days.

The Oregon Department of Environmental Quality warned Portlanders that their air was "unhealthy" on 25 separate occasions in August and September. The agency warned vulnerable populations to do what they could to avoid inhaling the tiny particles of dust and grit in smoke that can damage lung tissue and cause respiratory and cardiovascular problems.

As the climate continues to warm, such warnings are likely to arrive more frequently in the near future.

That's prompting some forest managers to discuss new strategies to avoid catastrophic fires, such as letting smaller fires burn instead of putting them out.

"One hundred years of suppressing all fires is one of the reasons we are in the situation we are now," says Traci Weaver, a spokeswoman for the U.S. Forest Service in Portland.

Many recent fires were supercharged by the warmer and drier conditions brought on by climate change, and dealt a catastrophic blow to communities.

Lives, health and property are at stake.

"This was a significant year for wildfire," says Ron Graham, Oregon Department of Forestry's deputy chief for fire protection. "Thanks to aggressive and safe firefighting, we were able to keep the great majority of fires small in scale."

"It is our policy to put out fires promptly," adds the department's spokesman, Jim Gersbach. The U.S. Forest Service has a similar policy to suppress wildfires, except in wilderness areas.

But some scientists are calling for a dramatic shift away from the current "Smokey Bear" policy of attempting to extinguish every fire.

Last year, the University of California-Berkeley released the results of a 40-year study at Yosemite National Park that found that "managing fire, rather than suppressing it, makes wilderness areas more resilient to fire."

A new paper published in a recent issue of the journal Ecological Applications by Matthew Reilly, while he was a scientist at Oregon State University, says the best way to avoid catastrophic fires may be to allow low- and moderate-severity fires to just burn.

"There's a push for restoration activities such as thinning and prescribed fire to make the forests more resilient," Reilly says. "And there has been some really good work done on the ground (on such efforts), but it's a drop in the bucket. It's hardly enough."

PHOTO BY GARRETT MEIGS, COURTESY OF OREGON STATE UNIVERSITY - All the mature ponderosa pines survived with minimal scarring in this section of forest near Camp Sherman in the 2003 B&B Complex fire. This image is from 2007. Reilly defines a low- and moderate-severity fire as one that "skunks around the forest consuming fuels like small pieces of dead wood, understory vegetation, and small midstory trees." Such fires, he says, can start as a small flare-up and reach up into the canopy of one or a few overstory trees.

"Over time, you get a forest or woodland with scattered large trees and an open understory," he says.

Reilly says that forested lands on the eastern side of the Cascade Mountains are especially vulnerable to a catastrophic fire, as only about 10 percent of the area has burned in the past 30 years. Efforts to reduce the vulnerability of these dense forests to catastrophic fires through tree thinning, prescribed burning and harvesting have had little overall effect on the health of forests, he says.

"Although most recent fires have been low- and moderate-severity, all it takes is a change in the weather, a dry east wind for example, and anything can happen," Reilly says.

"The longer the time between fires, the greater the potential for a high-severity fire that can threaten lives and property."

Firing up

Some 2,000 wildfires engulfed nearly 710,000 acres in Oregon in 2017.

That made it the fourth-busiest fire season in Oregon in the past 100 years in terms of burned acreage, according to the Oregon Department of Forestry.

Three of the six worst fire seasons in Oregon have all occurred since 2012, according to ODF. Only 2012 and 2014 saw more forest acreage burned than 2017.

Galvanized by powerful winds and dry conditions, wildfires this summer ripped through forests from California to British Columbia.

In California, wildfires destroyed 6,900 homes, causing more than $1 billion in damage and killing 42 people.

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