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Fuel Load Reduction Critical to Curbing Wildfires

LAS CRUCES - Field studies of wildfire sites in New Mexico and Arizona show that managing forests with careful timber harvests and prescribed burns can lessen wildfire danger and speed forest recovery, New Mexico State University researchers said.



Terrell Baker, an Extension riparian management specialist with New Mexico State University's Range Improvement Task Force, has found that active forest management, including thinning and burning, results in less intense fire behavior and more intact stands following a wildfire. To weigh the effectiveness of forest treatment methods, the NMSU researchers traveled to national forests throughout New Mexico and Arizona. (07/14/2003) (NMSU Agricultural Communications Photo by J. Victor Espinoza)

To evaluate forest management methods, the scientists traveled to national forests throughout New Mexico and Arizona to find adjacent treated and untreated forest stands where wildfire had passed through. Study sites were located within Arizona's 469,000-acre Rodeo-Chediski fire and New Mexico's 5,000-acre Oso, 15,400-acre PeZasco and 16,500-acre Scott-Able fires.

"Through pro-active management, we can reduce the severity of wildfire, as well as more effectively provide for multiple uses on the forests," said Terrell Baker, the project leader and an Extension riparian management specialist with NMSU's Range Improvement Task Force.

Fuel reduction can lessen fire severity, stressed Doug Cram, a fire ecologist with NMSU's animal resources department and one of the study leaders. Small diameter trees, particularly those with tops in the midstory, should be removed and then fine ground fuels such as dead leaves, twigs and pine needles can be managed with prescribed burns, he said.

In the past, information about fire treatments' effectiveness was based on anecdotal claims, Cram said. In other words, everybody had opinions on which treatment was best, but it wasn't scientifically tested. Among the treatments examined were timber harvests, precommercial thinning, forest health treatments, prescribed burning and a combination of several methods.

U.S. Forest Service personnel in New Mexico and Arizona cooperated on the study, which was funded by a grant from the USFS Rocky Mountain Research Station.

By matching adjacent slopes and assuming that weather conditions were the same when the wildfire plowed through the forest, the scientists could attribute any difference in fire behavior to a difference in fuel load. "Every treated stand experienced less severe canopy and ground damage, compared to adjacent untreated stands," Cram said.

The objective isn't to fireproof the forest, but to return to low-intensity, high-frequency fires and reduce the likelihood of catastrophic fires, Baker said. Southwest forests are adapted to fire, but fire suppression practices that began in the early 1900s contributed to today's unstable conditions, he said.

Fire has shaped New Mexico's forests for thousands of years, acting as a natural thinning agent that removes leaves, brush and small trees. But today's denser tree stands are vulnerable to catastrophic wildfires that kill trees, burn up wildlife habitat, damage forest soils, and, ultimately, forest productivity.

"After one of these intense fires there's a much higher incidence of topsoil runoff and sedimentation which overwhelm our drainages and streams," he said.

In the last few years, firefighters armed with shovels and backed up by slurry bombers have battled several huge wildfires across thousands of acres in New Mexico, Colorado and Arizona. The 2002 wildfire season was the most destructive in Colorado history with at least 235 homes destroyed and 915,000 acres charred.

This season's deadly wildfires are already underway. For the last month, firefighters fanned out around a raging wildfire north of Tucson in an attempt to beat back flames that incinerated about 70,000 acres and more than 300 mountaintop homes.

In New Mexico, conditions are ripe for another fiery summer. Bark beetles have damaged thousands of trees. Rainfall has been below normal, and efforts to get rid of the some excess fuel in the woods have met with mixed results.

The next phase of the NMSU project involves teaching the public about management practices to protect their communities and have a more productive and resilient forest, Baker said. The team plans to revisit many of the sites to measure a range of ecological variables to track forest health, he said.