Partial cutting impacts on moths and lepidopteran defoliators in a boreal mixedwood forest of Alberta (Choristoneura conflictana, Choristoneura fumiferana, Zeiraphera unfortunana, Operophtera bruceata)

A boreal lepidopteran community was assessed by whole-season light trapping for moths and whole-tree sampling for defoliators of aspen and spruce canopies in northern Alberta, Canada, before and immediately after logging with two different levels of green-tree retention. Partial cutting significantly decreased both moth trap catch and species richness, particularly of forest interior species, while generalist and pioneer plant feeder species increased in abundance. The larval community differed considerably between aspen and spruce canopies, yet was dominated by tortricid pests [Choristoneura conflictana (Clem.) on aspen and Choristoneura fumiferana (Clem.) and Zeiraphera unfortunana Powell on spruce) and one geometrid, Operophtera bruceata (Hulst), on aspen. Partial cutting showed potential for pest management as both spruce species investigated were less numerous per tree as the green-tree retention decreased. Post-harvest conservation of many forest species due to higher stand structure and plant diversity should increase biodiversity, at least for Lepidoptera, in the long-term.