<<Back to Fall 2011 Steward

Prescription for a Healthy Forest

 story by
David Abrams
Western Montana District

 prescribed burn ignition

Murray Douglas unit F10 during ignition.
BLM photo

Karin Riley observes controlled burn
USFS Missoula Fire Lab Analyst Karin Riley observes the controlled burn from an observation point on Elevation Mountain. 
BLM photo

The heat-resistant cameras were set up. The helicopters with the helitorches were on standby. The firefighters were suited up and ready to go. All that remained was selecting a favorable window of weather and fuel conditions—not an easy thing to do during this wetter-than-normal summer in the Rocky Mountains.

But on June 28, the Missoula Field Office got the right weather window and fire managers converged on the Garnet Mountains east of Missoula for a successful controlled fire treatment.

Steve Hancock, a fire management specialist with the Missoula Field Office, explained the 200-acre burn project was designed to move the vegetation in the area towards historic conditions “by altering species composition and structure and to restore the natural fire regime processes that the forest has evolved with.” All of this area has burned naturally in the past, each time maintaining natural meadows and openings across the landscape. The intent of the burn was to mimic those natural patterns. The prescription was for a mixed severity, or “stand replacement” fire, where much of the overstory vegetation would be removed.

One objective of the controlled burn was to restore a high-elevation meadow that had been overgrown by lodgepole pine and Douglas-fir trees. Among other things, the meadow restoration would improve the summer and autumn ranges of elk and deer. The Rocky Mountain Elk Foundation contributed to the project, just as it has in many of the vegetation management projects the BLM Missoula Field Office conducts.

The controlled burn also created a ridge-top fuel break which will help decrease the probability of large-scale, high-severity wildfire, Hancock said, adding, “The ridge-top fuel break is primarily intended to protect the adjacent Wales Creek Wilderness Study Area. It is also intended to protect public and private lands around the Wilderness Study Area in the event of a wildfire becoming established inside the Wales Creek drainage. This is especially important in this area,” Hancock noted, “because there’s an abundance of dead and dying trees due to the large-scale pine beetle epidemic which has been prevalent across Western Montana over the past several years.”

Fire managers often attempt to mimic natural disturbance patterns by arranging treatment areas in patches relative to the size in which they naturally occurred. To do this, managers analyze historical photographs. In this case, aerial photos from the 1930s were compared to recent aerial photos of the area to determine the size and location of where the vegetation treatment would be conducted.

The controlled burn didn’t just improve the condition of the forest—it also contributed to science by allowing researchers to get an up-close and personal look inside the flames. The USDA Forest Service Rocky Mountain Research Station-Missoula Fire Lab set up cameras and sensors that were able to withstand extremely high temperatures. The footage and data captured and the experiments conducted will help to better understand the dynamics involved in fire behavior and how they correlate to heat, combustion, and fire spread.

On the day of the controlled burn, a helicopter with a device called a “helitorch” was used to ignite selected areas of the project. Firefighters and fire engines from the BLM Western Montana District, Lolo National Forest, Beaverhead-Deerlodge National Forest, Helena National Forest, and the Missoula Smokejumpers were on the ground to mop-up and patrol the burn. Ignition lasted for two hours and the fire burned for another hour after ignition was completed. Just as the flames were starting to die down, the area received significant rainfall which helped keep the controlled burn within its intended boundaries. Prior to ignition of the burn, fire managers were aware that precipitation was likely in the afternoon due to weather forecasts issued earlier in the day.

Firefighters continued to mop up and patrol the project for several days to ensure the burn was secure. Fire managers utilized a thermal imaging camera operated from a helicopter in order to detect residual heat that could surface in the future as the summer turned warmer and drier. Fire managers continued to monitor the prescribed fire throughout the summer.

“As is the case with many controlled burn operations, there were many challenges involved in the successful completion of this project,” Hancock said. One major challenge was the abundance of dead and dying lodgepole pine trees in the area. “This created a highly volatile environment, typically difficult to conduct a controlled burn in,” he said. “Fuels inside the burn unit were mechanically arranged in a particular way to account for this, and the ignition pattern was conducted in a controlled manner.”

However, the abnormally cool and wet spring led to ideal burning conditions, as the above average snow pack and late run off created wet fuel conditions in the areas outside of the controlled burn, thus minimizing fire behavior outside of the unit. The south facing aspect of the controlled burn enabled the fuels inside of the unit to dry out much faster, resulting in much more intense fire behavior. Flames as high as 150 feet consumed the canopy, opening up meadows for deer and elk to use in the future.

“This was a significant and successful vegetation management project for our office, one which required not only a lot of hard work by our natural resource specialists, but also our cooperators from the USDA Forest Service,” Hancock said.

For more information about this project and the BLM Missoula Field Office Fuels Program, please contact Michael Albritton or Steve Hancock at (406) 329-3914.