SLOW BURN

BY WILL MATUSKA

Angie Busby woke up surrounded by a haze. Smoke from the East Troublesome Fire, the second largest wildfire in Colorado’s history, was covering Busby’s home north of Jamestown. She couldn’t see her hand in front of her face.

Just a few hours later, sustained wind gusts up to 80 mph helped start the nearby Cal-Wood Fire. While her home was not at risk, Busby, a trained wilderness firefighter and EMT, was on the scene “pretty much after the first smoke report till the end.”

“You disconnect from the fact that this is your home territory, and you just do what you need to do to make sure everybody is safe,” she says.

The Cal-Wood fire burned through more than 10,000 acres and 26 structures, including half of the Cal-Wood Education Center’s 1,200-acre property, where Busby is the natural resources manager.

Prior to the fire, most of Busby’s fire mitigation measures included things like thinning trees, opening up tree canopies, taking out diseased trees and cre- ating openings for meadows in an effort to emulate historical forest compositions and reduce fuel loads.

Three years later, she sees where those efforts worked and where they didn’t — and it’s changing how she approaches managing her land.

“In the last couple of years, there’s been a switch from just fuels reduction in the forest to home-hardening,” she says. Now, half of her time post-fire is spent increasing structure resilience.

Busby’s shifting views on land management are part of a larger discussion among scientists and land managers about what historical forest structures actually looked like. One new study published last month in the scientific journal Fire questions the science that informed today’s best practices in wildfire mitigation.

Ongoing Discussion

After more than a century of fire suppression and a two-decade megadrought, Colorado is experiencing more large fires than ever before. Ten of Colorado’s 20 largest fires by acreage have occurred since 2018. The 2021 Marshall Fire is the state’s most destructive fire by structure loss.

Tony Cheng, director of the Colorado Forest Restoration Institute, says Colorado has always had big fires, but “the key is those fires may be becoming more frequent over a longer period of the year and those fires are also intersecting with a variety of human values (like protecting structures) that are on today’s landscape that weren’t there 250 years ago.”

On Boulder County public lands, forest management and fire mitigation strategies center around land stewardship to improve forest health and structure, which includes forest-thinning and patch-cutting.

“Research for us on the Colorado Front Range tells us that the overgrown dense structure that we have is the issue,” says Stefan Reinold, resource management division manager at Boulder County Parks and Open Space.

A lot of the thinning in the county occurs in the lower montane forests where species like the ponderosa pine dominate the landscape. Patch cuts (clearing an entire area of trees) are done in the upper montane forests to species like the lodgepole pine to build age diversity and fire breaks. Those are typically less than 15 acres, according to Reinold.

“How a fire would burn with a more open structure is really what we’re after, [so we’re] changing the structure to one that can receive fire, rather than one that when it does receive fire, it is devastating,” says Reinold, adding that forest structure has historically been more open than it is today.

But the April 3 study in Fire, an international and peer-reviewed journal, found tree density and fire severity in pre-industrial dry forests were more variable than previously thought.

The study challenges the “low-severity” model, which argues these forests were low in tree density and had lowand moderate-severity fires. Instead, it highlights evidence indicating a “mixedseverity” model with both low and high tree densities and a mixture of fire