Wildfire scientist assesses Crescent burn’s effects
Perhaps unlike most people, Susan Prichard has fond memories associated with the smell of burned trees. As a young researcher, the University of Washington wildfire scientist spent a lot of time in the woods studying the aftermath of fires — or “which trees died and which ones lived” — she explained recently while hiking into the Crescent Fire burn area in the Twisp River watershed.
Prichard and her colleagues used to measure the diameters of burned trees by wrapping their arms around them. “That’s why they called us tree-huggers,” she chuckled. “It smells very strong right next to a tree when you’re hugging it.”
As she hiked into a section of the more than 50,000 acres that burned in the Crescent Fire last summer, Prichard’s well-trained eyes scanned the forest along the trail.
“What I’m seeing so far is not bad,” she said.
The surrounding forest is a mix of green, new growth from the recent rains and blackened standing dead trees — the usual Methow Valley mix of Ponderosa pine, Douglas fir and some aspen and cottonwood.
Prichard observed that the fire moved over the landscape inconsistently, burning some sections to black death and others only partially, in a sort of mosaic or patchwork pattern that makes wildfire scientists happy because it is true to historic, more-moderate burn patterns that are in stark contrast to the scorched black monotone of more-recent megafires in the West.
To the untrained eye, however, this forest looks dead — a graveyard of black trunks that could topple at any minute. Scorched, fallen trees block the trail ahead of Prichard at regular intervals, making it almost impassable for her and her industrious little mutt, Theo, who accompanied her on the reconnaissance hike.
“A lot of people coming back here might say that this now looks ugly, and I would probably agree with them, but at the same time, the fire had variable impacts. It’s not just 100% dead whatsoever. A lot of the bigger trees survived,” Prichard said, pausing beside a rushing creek. “So right here it feels like fire acted like a natural thinning agent, as well as a prescribed burn — it cleaned up a lot of the accumulated litter and branches on the forest floor. A little spot of good news.”
She pointed to a crooked Douglas Fir that looks like it’s wearing a tutu — long tendrils of scorched mistletoe hang down from a girdle in the trunk roughly 15 feet up from the ground. Mistletoe is a native pathogen, a sort of parasite that takes hold of Douglas fir trees and robs them of moisture and nutrients. It also acts as a helping hand or “ladder fuel” for fire, ushering a blaze from the forest floor up into the canopy of the tree and thereby allowing the fire to grow in intensity. Prichard observed that the Crescent Fire seems to have acted like a “bath” for this forest, killing off some of the parasitic mistletoe without killing the host trees.
Looking at survivors
Prichard hugged trees as a young scientist for good reason. When analyzing the effects of wildfire in a forest, Prichard explained, it’s important to look at which trees survived, and how big they are, because that provides an indication of how resilient that forest will be to drought and future fire.
Picture a stand of trees like a handful of drinking straws, shoved into a cup of water. The thicker straws — or bigger trees — will take up more water. When they are surrounded by thinner straws — or smaller, younger trees — those old growth giants can be robbed of the water they need to continue living for hundreds of years. When fire rolls through a forest, often the younger, smaller trees (or straws) are killed first, ensuring the cup has enough water for all the straws, instead of being sucked dry.
Fire, traditionally, has helped forests be more resistant to drought by effectively removing some of the excess “straws.” When forests are allowed to become overgrown, they can also become less healthy and more vulnerable to drought, Prichard explained as she scrambled over a downed trunk and pointed to a stand of scorched young trees, their trunks roughly 6-12 inches in diameter.
“The fire did a lot of good work in here. There’s a lot of dead trees in the understory, but if you look up, there’s a lot of living, large trees left,” she said.
More burning necessary
More than a third of the Methow River watershed has burned since 1990 but experts say more burning is necessary to thin the remaining forest and make it more resistant to megafires. The area burned by the Crescent Fire had not seen fire for more than 80 years, and it was due. Prichard says many blame the U.S. Forest Service for suppressing fire and contributing to overgrown forests, but there’s more to the story.
“The Forest Service wasn’t actively putting out fires here until 1940,” Prichard explained. “Native peoples used to live throughout the Methow Valley and they burned the forest frequently. Some of these fires that pruned the ponderosa pines were set by first peoples in the valley.”
With the loss of the native peoples and their land management practices, fire also left the landscape. Add to that sheep and cattle, which eliminated the grasses that used to carry fire through the understory of the forests on a fairly regular and moderate scale, and you have a recipe for a dangerous build-up of fire fuel.
The Crescent Fire burned for almost three months. No lives or property were lost but it contributed to weeks of poor air quality and many canceled vacation bookings in the valley. Prichard acknowledges those impacts, but after exploring this stretch of the Twisp River basin, she sees a silver lining.
“The fire had an ecological benefit to this area. It’s not bad, it’s not good, it’s just real. It’s fire doing its real work,” Prichard said, as she set about hunting for morel mushrooms on her way out of the blackened forest.