What if our efforts to stop wildfires in the woods actually make them bigger?
“It’s a counter-intuitive result,” said research ecologist Sean Parks. “We put out the fire, but in the long run, there are negative unintended consequences. If we’re putting out all fires under moderate weather conditions, the fire we can’t put out will burn under extreme conditions.”
Parks' work at the Aldo Leopold Wilderness Research Institute on the University of Montana campus recently earned him the 2017 Research & Development Deputy Chief’s Early Career Scientist Award. Since earning his doctorate from UM in 2014, he’s been lead author of nine peer-reviewed journal articles and co-authored another 11.
Much of Parks' work focuses on wildfire in federal wilderness, including the Bob Marshall Wilderness Complex and the Selway-Bitterroot Wilderness. Forest fires there typically burn without the swarms of yellow-shirted firefighters and red-tailed aircraft trying to suppress them.
Those fires may start early in the wet weeks of June or early July, and burn for days or weeks unopposed. Many die out unnoticed. Some grab headlines, like the 1988 Canyon Creek fire that blackened 247,000 acres across the Scapegoat Wilderness before stopping at the edge of Augusta.
Outside federal wilderness, federal land managers send firefighters to stop blazes within hours or days of detection. U.S. Forest Service crews extinguished between 97 percent and 98 percent of their fires by initial attack in 2016.
“I think outside wilderness areas, we’re selecting for high-severity fire,” Parks said. “It’s like selecting for a gene in corn crops. It’s not done on purpose, but it happens with certain management practices. We’re not allowing fires to burn in non-extreme years. So fires only occur during extreme events. Those fires are the ones we could not put out.”
Fires that burn in less than extreme conditions don't do as much damage to the landscape, but do provide good buffers against future fires. That helps the forest evolve to a drier, less fire-prone state often seen in wilderness areas.
The distinction between wilderness and non-wilderness matters because of other research Parks has done. Reviewing more than 1,000 wildfires in four large wilderness areas over four decades, he documented how well and how long a previously burned area retards a new fire.
“People know this in their gut, but there was very little research that quantifies the effect,” Parks said. "The effect lasts differently in New Mexico, where you have a warmer climate, and much longer in northern areas. This gives decision-makers evidence to back up their decisions.”
So a burn scar like Canyon Creek, created almost 30 years ago, won’t provide much hindrance to a new fire. On the other hand, 2017’s Rice Ridge fire should give lots of protection to the town of Seeley Lake’s northwest flank after the blaze burned 160,000 acres.
Parks' current work looks at how future climate changes may affect the tempo of fire seasons. He’s testing the idea that we’re likely to see more extreme fire events in the short term, but less severe fires several decades from now as the climate warms.
“We think we may see the spruce-fir forests converted to something else that may be more resistant to fire, like Douglas fir and ponderosa pine,” Parks said. “And at some lower elevations, dry-forest types are projected to convert to non-forest vegetation, grassland or shrub land. Dry forests are barely hanging on now.
“As Montanans, we’ve grown up with certain kinds of forests,” Parks added. “They are going to change. We can accept it, but it will happen whether we want it to or not.”