'What Causes the Perfect (Fire)Storm?' asks USU Ecologist

A cold, wet spring in the northern Rockies and anxious vigils of rising rivers has temporarily taken minds off wildfire, the region’s perennial summer worry. But northern Utah residents need only look a little south for rude reminders as Arizona’s massive Wallow Fire, the Los Alamos fire and infernos in southern Utah and other states have ravaged communities this season.

“Record snowpack levels should reduce fire risk at the higher elevations, but a wet spring means increased growth of weeds such as cheatgrass,” says Utah State University ecologist Mike Jenkins. “Grasses and weeds dry quickly and could present a significant fire risk as summer temperatures rise.”

Jenkins is the recipient of a three-year Joint Fire Science Program grant administered by the Bureau of Land Management. With his proposal, “The Influence of Fuel Moisture and Flammable Monoterpenes on the Combustibility of Conifer Fuels,” he secured about $420,000 to study interactions between bark beetles, varied conifers and fuels. Jenkins’ study area includes Utah, Nevada, southwestern Wyoming and southern Idaho.

Traveling through western forests, visitors can easily spot the effects of bark beetle outbreaks that have resulted in the loss of hundreds of thousands of pine, spruce and fir trees. A 2009 USDA Forest Service report states that weakened stand conditions and drought, combined with warming temperatures, have contributed to the severity of these outbreaks, particularly in high-elevation forests.

Jenkins says conventional wisdom suggests that large scale bark beetle outbreaks alter fuel complexes resulting in an increased potential for severe fires. Conversely, scientists and forest managers surmise that fire-damaged trees are more vulnerable to beetle attacks.

But is this actually the case?

“It’s not as clear cut as some think,” says Jenkins, associate professor in USU’s Department of Wildland Resources and the USU Ecology Center. “Some believe that bark beetles create conditions conducive to wildfires, but those conclusions are premature. There’s still a lot we don’t know.”

Bark beetles, which feed on dead trees, are, after all, natural recyclers in forests. Other factors that may have increased forests’ susceptibility to wildfire include a century of forestry management practices such as fire suppression that encourages growth of forest fuels, as well as logging, grazing and development.

In the course of his study, Jenkins will collect moisture data and terpene samples — flammable compounds from varied conifers — at different sites and elevations. In the lab, he and his student team will ignite samples to determine each specimen’s heat of combustion.

“Using physics-based fire models, we hope to better quantify interactions between beetles, fire and fuel and determine what factors increase the probability and severity of fires,” he says.

Quantified data, Jenkins says, could help forest managers determine how to manage bark beetle infestations to reduce fire probability and intensity. In addition, the findings could contribute to knowledge of wildfire behavior.

“Our research and studies like it have important safety implications,” says Jenkins, who served as a superintendent for a Forest Service firefighting hotshot crew during his student years. “Knowing more about how and why fires burn helps firefighters be more aware of fire behavior and how to safely contain them.”

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Contact: Mike Jenkins, 435-797-2531, mike.jenkins@usu.edu

Writer: Mary-Ann Muffoletto, 435-797-3517, maryann.muffoletto@usu.edu