KAJX

Fire science: Burning prescribed to treat landscape

Apr 18, 2017

A firefighter pours flames on a prescribed fire at Avalanche Creek.
Credit Elizabeth Stewart-Severy/Aspen Public Radio News

It’s mid-April, with mild temperatures and sunshine on the snow-capped peaks above Avalanche Creek. The grasses and shrubs along the valley floor are still golden brown, inching toward green. It won’t rain today but there’s a front moving in tomorrow, and it’s windy. All of this means the variables are coming together for fire.

“It’s not rocket science,” said Jim Genung, fuels specialist and burn boss for the White River National Forest. “No, it’s fire science. It’s tough to nail down. It’s fire.”

Genung spends the winter months writing the prescriptions for fires like the one earlier this month up Avalanche Creek near Carbondale. These fires are planned for the spring, after the snow melts at lower elevations but before all the vegetation goes green. A wide range of conditions need to line up just right, especially in places like this, where there are homes just a few miles away.

“We can’t just go out and start throwing fire around,” Genung said. “We need to keep things kind of small.”

At the same time, Genung and the crews need to make sure that the brush is dry enough so the fire actually catches and can do its work. This fire is part of a forest-wide plan to regenerate wildlife habitat each year, with about 6,000 acres of landscape targeted for burning annually.

On this April morning, Genung started with a small test burn to see how the fuels are igniting and if the conditions will cooperate.  

“We’ve got a really secure piece of ground here to work with today, this first section of about 80 acres,” he said.

The area is bound by the dirt road on one side and Avalanche Creek on the other. A team of firefighters walked slowly through the brush. They held small cans with a diesel-gasoline mix, with a burning wick at the end that poured flames onto the ground. They started near the road and creek, which contained the fire’s boundaries.

Jim Genung explains the conditions necessary for prescribed fire.
Credit Elizabeth Stewart-Severy/Aspen Public Radio News

This ecosystem is adapted to and dependent on fire. Genung said the Avalanche Creek valley would have burned about every 50 to 75 years before people settled near here. Fire suppression and human activity have prevented two or three natural cycles.

Now the gambol oak and serviceberry are old, tough, and decadent. The aging brush burns, creating space and high-quality soil where younger, nutrient-rich vegetation will take root. This is good news for bighorn sheep, elk and deer.

“We’re trying to give them back their habitat,” Genung said.

The bighorn sheep herd in this area, especially, is in need of some help.

“They don’t like to travel through thick brush,” said Kate Jerman with the Forest Service. “We want to clear some space for them to get through the brush.”

The fire creates open pathways for them to get water from the creek, with space to actually see predators.

It has the added benefit of reducing dry brush near homes, in this case, the Swiss Village just down the valley.

“We’re putting the good fire back out on the landscape,” Genung said. “And we’re creating an area that’s less susceptible to high-risk, extreme type fire behavior that we don’t want this close to town or to homes.”

For weeks before the burn, Genung closely monitored a wide range of conditions: moisture levels in the fuels, humidity, precipitation, temperature, cloud cover, and wind speed and direction. Everything looked right for this particular day, but it was really windy as he and about 15 firefighters started a small test burn in Avalanche Creek.

“The volatility we have in the atmosphere today is actually good for smoke,” he explained. “It’s going to disperse the smoke well, we’re not going to have any problems with smoke settling in any towns today, and that’s really a big deal for us.”

Those winds did clear the smoke out from the area, but they also limited the scope of this year’s burn. The Forest Service covered 90 acres, well short of the goal of up to 500 acres. This is the third year that the Forest Service has burned in Avalanche Creek.

“It’s generally going to take two to three treatments on the same piece of ground over a 15-year period to get things back to where maybe they should be,” Genung said.  

Forest-wide, that will take even longer. About 40,000 acres of habitat have been identified as needing treatment through prescribed burning in the White River National Forest. It’s a landscape wide project, made up of a series of postage-stamp sized individual burns, like this one — a project that hopefully will knit together a full mosaic of healthy land.