Picture an unusually dry summer, a record heat wave, and so many Western fires burning that crews are stretched thin across the country. And a fire started that “spread so quickly, and burned so hot, and moved so fast” that “it looked like Mount St. Helens erupting.” And with winter rains nowhere in sight, “it felt like it was gonna go on forever.” Debates about the best way to prevent such fires raged: Do you thin the trees? Conduct prescribed burns? Put fires out as soon as they start, or let them burn?
Summer of 2021? Nope. Those quotes are from an award-winning episode of “Oregon Field Guide” that documented the 2002 Biscuit fire. At 500,000 acres, it was the largest fire to burn in Oregon since 1900. The terms “climate change” and “global warming” were never mentioned. While the Field Guide team was filming, former Vice President Al Gore was touring town halls around the country, presenting a slideshow about climate change that would later become the documentary film “An Inconvenient Truth.”
Today precedent-setting fires are almost routine. Any number of superlatives apply to today’s Bootleg Fire, which started unseasonably early and exploded to 400,000 acres in a handful of days.
The Biscuit Fire was a warning: If it gets dry enough and hot enough, Oregon’s forests become the perfect fuel. The fire also provided a research opportunity. It was a chance to shed light on some burning questions, to see how clearcutting, thinning, controlled burns, and a combination of controlled burning and thinning impacted fire behavior.
The Biscuit Fire burned through a portion of forest set aside for research, with different plots managed in different ways. When the Biscuit Fire burned, those research plots also went up in flames. At first, it seemed like a loss. Instead, it proved a gold mine of research.
The premise behind both thinning and controlled burning is to remove some of the fuels and stop the fire from getting too hot. Thinning is supposed to remove smaller trees, or “ladder fuels,” that can ignite and send flames toward the tops of trees. Controlled burns remove the layers of needles, detritus, grasses, and brush that make up the forest floor.
”What I am walking along is the fire line for the underburning study,” Bernard Bormann, a forest ecologist, told OPB’s Oregon Field Guide in 2002. At the time, he was working for the U.S. Forest Service. “The area to my left was underburned in 2001. This area was not. They were both thinned in the same way.”
To the right, there was stark, black earth. But the area to the left, which had been deliberately burned two years prior, was speckled with green: new shoots of small plants that had survived the less-hot fire.
And looking skyward, the difference was even more pronounced.
“You can see there are some dead trees here, but many of them are alive and have branches, even, low down. On the other extreme,” he gestured to the left, “you see very few live trees at all. It’s hard not to conclude that the underburning treatment, at least in this particular spot, was very effective.”
And, even more surprising: In areas that were just thinned, and not burned, the fire appeared to be hotter than areas that weren’t treated at all.
At the time, some in the timber industry saw the fires as a sign of failed forest management; if they could just cut down the trees, there would be less to burn.
But on the clear-cut plots and in areas where ladder fuels were thinned, but no burning happened, the Biscuit Fire burned hot and fast. Bormann thinks the hardwood trees that would normally be removed in thinning operations helped dampen the fire. That hypothesis was put to the test in 2020, when a test plot containing Douglas fir and red alder burned in the Holiday Farm Fire. Bormann said research on that location is ongoing.
In 2002, Bormann was careful to note that all forests are different, and it’s hard to draw conclusions from a single study. And Bormann, now at the University of Washington, is still careful today. “It’s just an anecdote, you know. But it’s pretty obvious.”
And there are a lot more anecdotes now than there were in 2002. In the 2020 Holiday Farm Fire, clear cuts burned hotter and faster than unlogged forest. And more and more wildfires are burning across land treated with prescribed fire.
Lessons from the Deschutes National Forest
The Deschutes National Forest in Central Oregon looks very different from the southwest Oregon forest burned in the Biscuit Fire. Officials at the Deschutes are experts on prescribed burns, many of which they conduct as part of the Deschutes Collaborative Forest Project.
“Because Central Oregon is a fire-adapted forest, we have kind of been one of the forests at the forefront of reintroducing fire into the system,” said Jean Nelson-Dean, the public affairs officer for Deschutes National Forest. Each prescribed burn takes years of planning. Other forest officials send crews from around the country to train with crews from Deschutes.
All of that prescribed burning has paid off. In 2020, the Rosland Road Fire broke out north of La Pine, Oregon.
“There were immediate evacuations,” Nelson-Dean recalled. It burned hot and fast through dense forest, but once it reached an area where fuels were removed through thinning and fire, “it just dropped to the ground, and they were able to put the fire out.”
No homes were destroyed.
And in 2017, the lightning-caused Milli Fire came roaring down the Cascade Mountains and toward the town of Sisters. As with so many fires recently, it burned too hot and too fast for crews to get close to the fire. They could only fight it from a distance.
Just a few miles out of town, the fire reached an area treated with prescribed burning. Again, the fire dropped to the ground, where it became more manageable. “That allowed crews to get in and take direct action on the fire, because it was safe,” Nelson-Dean said.
The reduced fuels let crews stop the Milli fire in its tracks.
It’s happening again, right now. The Bootleg Fire burned into the Sycan Marsh, which is managed by the Nature Conservancy. In areas of the marsh that were treated with prescribed fire and thinning, the Bootleg fire appears to have burned less intensely.
At the Biscuit Fire, prescribed burns were done for research. The prescribed burns around Sisters and the Rosland Road fire were conducted to protect nearby towns. At Sycan Marsh, the fires were set for the benefit of the ecosystem.
Frequent, smaller fires are a normal part of many of Oregon’s forest ecosystems. Peck’s penstemon, a flower only found in two watersheds of the Deschutes National Forest, relies on the disturbances created by fire to exist. Some plants need fire to germinate. Some, like manzanita, burn like crazy, a trick to kill the manzanita’s competition, creating plains of chaparral.
But as research on the necessity of small fires has grown, other questions have emerged, like what happens to the ecosystem when these unprecedented, large fires rage?
Here, again, past megafires can lend some hints. In the 2002 Biscuit Fire, Bormann returned to research sites to find a new layer of rock covering the ground. All the nutrient-rich topsoil had disappeared in the fire, either burned or dragged upwards by wind. Ongoing research suggests the dirt is long gone, pulled up with the smoke and scattered on the winds.
And it’s not just the dirt that’s gone; the fire took the nutrients plants need to survive, too. In 2015, Bormann learned that areas burned by the Biscuit Fire had much less nitrogen, phosphorus and carbon left in the soil than areas that weren’t burned by the Biscuit Fire. Plots treated with prescribed burns had a bit fewer nutrients, but not much. He’s seen similar results in other areas.
In a field where research happens at the speed a tree grows, it’s still not clear what the long-term impacts of that nutrient depletion will be.
It’s possible the Bootleg Fire will provide more anecdotes, another thread in the complex relationship between Oregon’s forests and the fires that burn them.
Or maybe that information will come from future fires. The Bootleg Fire is almost contained, but we’re in the early days of August. This is a time that, in less-hot decades, marked the start of Oregon’s fire season.