Insect disturbance is thought to increase fire risk by increasing dead fuels across large landscapes. Insect disturbances, however, also modify tree species composition and structure to influence fire disturbances across longer time scales. Forest Service scientists and their partners applied a landscape succession and disturbance model (LANDIS-II) to evaluate the relative strength of interactions among eastern spruce budworm (a native but destructive insect that feeds on the needles of fir and spruce), vegetation change, and fire disturbances in the Boundary Waters Canoe Area (BWCA) in northern Minnesota.
They found that spruce budworm disturbance decreased area burned and fire severity when averaged across 300-year simulations. They concluded that budworm disturbance can partially mitigate long-term future fire risk by periodically reducing live ladder fuels within the mixed forest types of BWCA, although budworm disturbance will do little to reverse the compositional trends caused, in part, by fire suppression. These results have important ramifications for fire mitigation strategies and ecosystem restoration initiatives in the region.