Prescribed fire is ignited with torches in an effort to restore forest health and create zones that are defensible.
 photo by Jim Cornelius
Prescribed fire is ignited with torches in an effort to restore forest health and create zones that are defensible. photo by Jim Cornelius
After 15 years of massive and severe blazes that have blackened landscape and choked the community with smoke for weeks at a time, severely disrupting people’s lives and the local economy, Sisters lives in dread of wildfire each summer.

To push back against those impacts, foresters must fight fire with fire: specifically, prescribed fire.

Fire is not the enemy of the forest — in fact, it’s essential to the forest’s health. Ponderosa pine forests like those of Sisters Country need fire to clear out underbrush and small trees and allow the big trees to become towering, resilient giants.

“That’s two thirds of our landscape,” says Pete Caligiuri, a forest ecologist with the Nature Conservancy. “We live next to these frequent-fire-adapted landscapes.”

After decades of fire suppression, Oregon’s forests are overloaded and full of fuel that makes big wildfires burn higher, hotter and more destructively than they should.

Caligiuri noted that 4.4 million acres of forest in Oregon are in need of restoration — 400,000 to 450,000 on the Deschutes National Forest — and “part of that restoration is reintroducing that natural, low-intensity fire to those forests.”

Caligiuri was one of the leaders of a tour last Saturday of a prescribed burning operation east of La Pine.

Fire is not the only treatment applied to restore forests to more natural conditions. Thinning trees through logging of smaller trees and mowing underbrush are employed broadly across the forest. Prescribed burning is often applied after a section of forest has been thinned and mowed.

A great deal of planning goes into prescribed burning operations – from the logistics of managing the fire itself to avoiding or mitigating impacts on wildlife. Detailed and highly specific burn plans are developed for each action, which identify nests and other wildlife habitat and recreational resources that must be protected.

“In that burn plan, there’s going to be some specific requirements for things we’re going to protect,” said Forest Service Supervisory Resource Team Leader Bill Monroe.

That can mean placing a cordon around nesting sites — and it can mean working with communities to avoid burning during cultural and athletic events. That was done last weekend as the Forest Service paused in its burning in the Sisters area to avoid having an impact on the SALI lacrosse tournament.

Burn operations are also coordinated so as not to impact too many areas, such as hiking and cycling trails, at the same time.

“There’s a lot of things to consider, and we do our best every day to make sure we’ve got them all covered,” Monroe said.

Deschutes County Forester Ed Keith noted that burning offers advantages in addition to improved forest health. Areas that have undergone prescribed burns are more defensible. Firefighters have seen that when wildfire hits previously burned areas, it drops in intensity, allowing firefighters to go hand-to-hand with the blaze.

“That dramatically changes wildfire behavior,” Keith said.

That change in wildfire behavior means that effective fire defense requires burning very close to residential communities.

Local residents have, over a period of years, come to understand the benefits of prescribed burning in protecting their homes and communities — but they still don’t like smoke in the air.

“We realize that we’re not going to convince anybody to like smoke,” Keith said.

Fire managers strive to burn only on days when conditions allow smoke to be lifted up and away from communities — but there are inevitably impacts. Cold air and becalmed winds in overnight hours mean that smoke often settles down to the ground, especially in watercourse drainages. And that can mean it percolates into communities.

Prescribed burns are ignited by teams wielding torches, dripping lighted fuel in dot or dash patterns, designed to catch burn back into already burned areas. The column from a prescribed burn can look identical to a wildfire, leading observers sometimes to worry that a burn has gotten out of control.

Burn plans call for specific outcomes, including allowable percentages of tree mortality. Observers of recently burned areas are often shocked to see blackened trunks and needles scorched red. The trees, to a layperson, look like they’re dead. However in most cases, the trees not only survive and green up again in subsequent years — they actually become healthier and more resilient. As Caligiuri notes, it is exposure to fire that makes the big pondos grow with smooth, limb-free trunks and thick, plated bark.

Fire managers have a narrow window in which it’s safe to burn and when the social impacts of smoke can be mitigated. That means only a small percentage of the forest that needs treatment actually gets treated in a given year. It’s a slow, incremental process to reintroduce an element that is critical both to the health of a treasured resource and to the safety of the communities that lie within it.