Long-term impact of severe wildfire and post-wildfire salvage logging on macroinvertebrate assemblage structure in Alberta's Rocky Mountains

Abstract

Wildfire is an important natural disturbance on forested landscapes influencing both physical and biological processes. The Lost Creek wildfire was one of the most severe on Alberta’s eastern slopes and provided a unique opportunity to assess the long-term impacts of wildfire and post-wildfire salvage logging on northern Rocky Mountain catchments. Macroinvertebrate sampling conducted 8 years after the wildfire indicated distinct macroinvertebrate assemblages in reference, burned, and burned and salvage-logged catchments. Reference catchments were characterised by more sensitive taxa (e.g. stoneflies) and had the lowest abundance of macroinvertebrates. Burned catchments had the greatest abundance of macroinvertebrates and were characterised by greater abundance of chironomids and caddisflies. Burned and salvage-logged catchments supported high numbers of riffle beetles and crane flies. The unique assemblage structures between catchments indicate different mechanisms drive the ecological response in wildfire-affected catchments. Resource availability was an important driver of assemblage structure in the more productive burned catchments and habitat quality was a dominant driver in the burned and salvage-logged catchments. Despite the legacy effects observed in this study, fire-affected catchments still supported sensitive taxa and functional macroinvertebrate assemblages.