Recent research suggests dead-tree zones of forests killed by the mountain pine beetle may slow the spread of wildfires. Although the red needles and skeletal trunks look like a rich fuel source ready to burst into flames, living evergreens have more volatile oil in their needles and burn more readily. Once killed, pines drop needles that decompose relatively quickly on the forest floor, leaving little flammable litter to burn and ignite the naked tree trunks. Without small fuel to feed the flames, the large standing logs do not readily catch fire. The phenomenon of dead trees serving as a fire break was observed after the Yellowstone fires of 1998: wildfires slowed or even burned out because there was insufficient small fuel among the standing dead trees to sustain them.
The researchers, however, do cite a shared condition exacerbating both the pine-beetle infestation and wildfire activity: climate change. With warming temperatures, pine beetles are surviving winters in greater numbers and in expanded ranges. Warming temperatures also cause the drier forests conditions that feed massive wildfires.
In their study, published in the September issue of the journal BioScience, the researchers point out that both insect pests and wildfire are natural components of the forest ecology and essential to forest health. Another study, published by the Ecological Society of America, examines the dynamics of pests in North American forests under climate change and predicts intensified insect outbreaks and expanding ranges as temperatures warm.