Impacts of aggregated retention harvesting on the diversity patterns of nocturnal moth species assemblages in the mixedwood boreal forest of northwestern Alberta

The loss of mature forest habitat from forest harvesting represents a substantial threat to the diversity of nocturnal boreal forest moth assemblages. In this study, I used spatial patterns of species diversity to quantify the effects of aggregated green tree retention harvesting on the diversity and composition of nocturnal forest moths. Ultra-violet light traps were used to sample moths in a 400 ha of intact boreal forest and a similar sized area of harvested boreal forest in northwestern Alberta, Canada. The results showed that the harvested forest supported a significantly lower number of moth species and limited the distribution of the moth species possessing relatively narrow diet breadths. Although relatively large patches of aggregated green tree retention supported diverse moth assemblages similar in composition to those present in undisturbed boreal forest, the substantial loss of mature forest habitat caused by forest harvesting substantially reduced the overall moth species richness.