Interactions among the mountain pine beetle, fires, and fuels

Bark beetle outbreaks and wildfires are principal drivers of change in western North American forests, and both have increased in severity and extent in recent years. These two agents of disturbance interact in complex ways to shape forest structure and composition. For example, mountain pine beetle, Dendroctonus ponderosae Hopkins, epidemics alter forest fuels with consequences for the frequency and intensity of wildfires and, conversely, fire injury to trees can promote bark beetle attack and increase beetle populations. Given the great influence these processes have on forest ecosystems, a better understanding of how bark beetles and fires interact is needed to better manage forests and to predict and manage wildfires. Here we review current knowledge on how fire and bark beetles interact, focusing on the mountain pine beetle. We highlight research on how fuel reduction treatments and wildfires affect bark beetles and how bark beetles can affect wildfires by modifying the moisture content, chemistry, and structure of fuels. Last, we discuss the implications these findings have for fire management and firefighter safety.