The post burning response of bark beetles to prescribed burning treatments in northern

Abstract—Ecologists and fire scientists have recommended reintroducing fire in fire-dependent ecosystems to achieve the twin goals of restoring pre-settlement forest conditions and reducing catastrophic fire risk (McKelvey 1996, Parsons 1995). Early work by forest entomologists (Miller 1927, Miller 1960; Rasmussen et al. 1996, Salman 1934) established a direct relationship between fire injury and subsequent insect attack in burned-over areas. Initial concern has centered on the primary tree killers Dendroctonus spp. and Scolytus ventralis LeConte. This research is also finding that Dendroctonus valens and Ips pini are causing tree mortality with both fall and spring prescribed burns. Post-burning bark beetle induced mortality can be quite signifi-cant as demonstrated by two case studies presented here from Lassen Volcanic National Park and Spooner Summit, Lake Tahoe Basin Management Unit. From these two sites, inferences are made on the effect of seasonality for predisposing trees to particular bark beetles. In comparing these two populations, there was no significant difference in the mean number of trees killed by insects in each seasonal window. As case studies, not enough replicates existed to merit a more rigorous analysis. As such, management implications of post-burning bark beetle response are discussed given the information available on fire-insect interactions during these two seasonal windows