Smoke effects from last week’s fires were pretty minimal — except for a period on Thursday morning when cold, still air pushed smoke into town. Photo by Charlie Kanzig
Smoke effects from last week’s fires were pretty minimal — except for a period on Thursday morning when cold, still air pushed smoke into town. Photo by Charlie Kanzig
Sisters residents get jittery when they see a big plume of smoke on the horizon. Two decades of wildfires that have seriously disrupted life in Sisters Country will do that.

But the smoke that billowed up to the south of town last week bodes well for Sisters, fuels specialists and fire managers say. The smoke came from a multi-day prescribed fire in the Sisters Area Fuels Reduction (SAFR) project area, approximately three miles southwest of Sisters along the 1505 Road.

“It looked to me like a beautiful, textbook burn,” Rod Bonacker told The Nugget.

Bonacker has years of firefighting for the U.S. Forest Service under his belt — and first-hand experience with the way in which prescribed fire helps firefighters battle wildfire. In 2012, Bonacker was part of the team that was trying to get ahead of the Pole Creek Fire, building fire breaks at night. The fire was a real threat to Sisters.

Last summer, he recounted the fight to members of a field trip out to the SAFR project area.

“Strategically, we needed to stop the fire spreading east and southeast,” he told them.

When a moving wildfire hits previously thinned and treated areas, it tends to drop to the ground and slow down, giving firefighters an opportunity to fight it safely and get containment lines around it. Areas treated in SAFR provided an opportunity for fire crews.

“That’s where we elected to do our work,” Bonacker recalled. “We were essentially linking those treated units that we already had. We essentially put a U-shaped control line around the southeast and the south end of the fire.”

Without those previously treated areas, “we would have had 10 times more work to do,” Bonacker said.

Last weekend, Bonacker told The Nugget that the recent burns help complete a treated strip southwest of town, what Bonacker called “a pretty significant barrier.

“The completion of that work really makes a tremendous difference,” he said. “It gives a place to fight the inevitable [wildfire] from.”

Prescribed burning consumes fuels on the ground and brush and low limbs that create “ladder fuels” that let fire climb into the crown of trees. A crown fire is a nightmare for firefighters.

In treated areas, “you have a fire that stays on the ground and is controllable by the ground troops,” Bonacker said.

The mass of smoke from last week’s burns may have looked ominous, but it was indicative of success.

“In this country, you don’t get to burn on a northeast wind very often,” Bonacker said. “They were able to take advantage of the wind and get things done.”

While it makes citizens nervous to see the Forest Service burning on days with wind, the fires are fully staffed with wildland firefighting crews. And wind is actually essential to doing the work effectively, according to Oregon State University Extension Service Regional Fire Specialist Ariel Cowan.

“You need some wind to help push the fire in the direction you want it to go,” she said.

Cowan noted that wind disperses smoke and lifts it out of the tree canopy, where it otherwise might hold in heat that can damage or kill trees.

The health of the trees in Sisters’ forests is a key consideration in prescribed burning. Done effectively, Cowan notes, prescribed fire helps build resilience in individual trees and the forest as a whole. Ponderosa pines, which dominate Sisters’ forests, are adapted to fire. When touched by low intensity burning, they actually get stronger.

“It’s kind of like an immune boost for the trees,” Cowan said. “It encourages thicker bark growth.”

And the thinning of stands reduces competition among trees and allows robust trees to thrive.

If fire burns at the low-intensity level that it should under natural conditions, it’s good for soil, too.

“Really, there’s a beneficial release of nutrients into the soil from combustion of the material on the forest floor that you wouldn’t get from just cutting the trees.”

Some local residents who have suffered from the impact of heavy wildfire smoke over the years might prefer that the Forest Service stick to cutting small trees and mowing brush. Fire managers are cognizant of smoke impacts and try to burn when they are minimized. Although last week’s smoke mostly stayed out of Sisters, there was a period of a few hours on a cold, still Thursday morning when the smoke settled in — and the lungs felt it.

Cowan said that mechanical thinning is an important component of forest treatment — but it’s not sufficient. In a fire-adapted landscape, burning is necessary to consume the fuels left on the ground g.

Burning for safety and for forest health will be an ongoing process. Areas that have been treated need to be re-entered every 10 to 20 years or so to mimic the natural fire regime.

“It’s not a one-and-done kind of thing,” Cowan said. “It’s tricky, because we have so many acres to treat.’

Burning continues Wednesday and Friday near Black Pine Springs Campground seven miles south of Sisters.