Thinning Forests to Reduce Fire Risk

April 5, 2017

To restore a forest and reduce the risk of severe wildfires, a conservation group is cutting down trees.

But it’s not a typical commercial logging operation. The Nature Conservancy is selectively logging dry forests in Washington’s Central Cascades as part of a long-term plan to make thousands of privately owned forestland more resilient to fire, disease and climate change.

A century of wildfire suppression has resulted in overgrown trees that are ripe for fire, so the group is weeding out smaller trees that can serve as kindling for larger fires. They’re leaving bigger, older and more fire-resistant ponderosa pines while removing tree species such as grand fir that are more susceptible to fire.

“We’re changing how the fire would burn, and changing it from severe to a fire that would be good and would maintain forest health,” said Ryan Haugo, senior forest ecologist at The Nature Conservancy. “We’re trying to mimic the role that fire would naturally play.”

The restoration thinning project outside the city of Cle Elum represents a fraction of the millions of acres that some say need to be treated to prevent the kind of intense wildfires that have scorched thousands of acres across Washington and the U.S. West.

A 2014 analysis by The Nature Conservancy and the U.S. Forest Service identified more than 11 million acres of dry forest in Oregon and Washington that are in need of restoration. It also said restoration thinning and burning are immediately needed on about 9.5 million acres.

Not everyone agrees on what role thinning should play in restoring forests or at what pace and scale it should happen.

Some say thinning, if not done right or strategically, may cause more harm than good, especially when new roads are built or commercial logging is done in remote or sensitive areas. Others worry that too often restoration is used as a blanket excuse to commercially log more public lands.

Dominick DellaSala, chief scientist of the Geos Institute in Ashland, Oregon, said thinning that’s done right can be a good tool but it’s not the only one.

“I don’t see it as a panacea and it should be strategically used to defend homes and lives and get into the truly flammable area,” he said. Often missing from the equation is letting fires burn naturally under safe conditions, he added.

On a cold winter day, a small local crew hired by The Nature Conservancy used a yarder, a large piece of logging equipment, to haul freshly cut trees, some about 100 feet in length, up a steep hill to the snow-covered road.

For much of the past winter, the crew has been working their way through thinning about 100 acres of dense forestland high above Cle Elum Lake.

The private forestland is part of nearly 48,000 acres on the east slopes of the Cascades that the group bought from Plum Creek Timber in 2014 with the goal of conserving land, protecting wildlife habitat and providing recreation access while also actively managing the forest, including logging to pay for restoration activities.

Crews use a cable system to haul the logs up. Once the logs are stacked in a pile, another worker revs up a chain saw and trims out smaller limbs. He marks them for length so they can be hauled to saw mills in the state where they are sold for timber products.

Not all the group’s forestland is suitable to commercial thinning. In some places, the group will weed out smaller trees but won’t sell the wood. But in places where they can, the group is trying to produce income to offset costs of managing the land.

“What we’re trying to show is that this is sustainable. You can make a profit here and treat a lot of these forests that need to be treated,” said Brian Mize, Central Cascades field forester for the Nature Conservancy.

“I don’t know if we’re going to convince everybody. But we have a tree problem,” Mize added. ‘We have too many trees. They’re primarily the wrong species. Just doing nothing, I think we what know the results are going to be, especially in the context of climate change.”

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