Response of saproxylic insect communities to logging history, tree species, stage of decay, and wood posture in the central Nearctic boreal forest

Abstract

Saproxylic insect assemblages are essential functional components of forest ecosystems that can be affected by forest management. We used a split-plot ANOVA design to analyze differences in selected saproxylic insects (all arthropod orders and dipteran and parasitic hymenopteran families) emerging from dead wood of sites with different logging histories (horse-logged, mechanically-logged and unlogged), tree species (Populus and Picea), stage of decay (early- and late-decay stages) and posture (standing and downed logs) in the boreal forest of central Canada. No clear effects of logging history were seen for the studied taxa; however, interaction between logging history and other dead wood features was apparent. Cecidomyiidae consistently emerged more from Populus than from Picea dead wood. Most of the studied saproxylic families were more abundant in late-decay than in early-decay wood. Dipterans of the Cecidomyiidae, Ceratopogonidae, Empididae, Mycetophilidae and Sciaridae families, and hymenopterans of the Diapriidae and Ichneumonidae families were significantly more abundant in downed than in standing dead wood. In contrast, Mymaridae was most abundant in standing dead wood. Our study provides evidence that some insects at high taxonomic levels respond differently to dead wood quality, and this could inform future management strategies in the boreal forest for the conservation of saproxylic fauna and their ecological functions.