Living on the edge: Effects of clear-cut created ecotones on nocturnal macromoth assemblages in the eastern boreal forest, Canada

Abstract

Forest management increases the amount of edges or ecotones on the landscape. Ecotones are important transition zones, representing a rapid change in landscape physiognomy and can support greater biodiversity than the adjacent habitats. It is therefore essential to understand how species respond to such habitat transitions. The Lepidoptera (moths and butterflies) provide numerous important ecosystem services in forests as herbivores, pollinators, and as food for many birds, bats, and other animals. It is therefore important to understand how this taxon responds to forest management in the boreal forest, and specifically how Lepidoptera assemblages change across anthropogenic forest edges. Via light trapping in clear-cut, forest, and edge habitats, we quantified the extent to which forestry-created ecotones influence nocturnal macromoth assemblages in the eastern boreal forest. We estimated species diversity as Hill numbers, calculated abundance, assessed composition with nonmetric multidimensional scaling ordination, and used indicator species analysis to determine how assemblage structure differed between the three habitats. We collected a total of 3486 individuals, representing 187 species that belonged to six families over 108 trap-nights. We collected a higher abundance of nocturnal macromoths in edges than clear-cuts, but not than forest. The composition of edges was intermediate between clear-cuts and forests, but differed significantly from adjacent habitats and included many unique species. Forest sites supported lower species richness, Simpson diversity and Shannon diversity than clear-cuts and edges, which overlapped with each other. Overall, our study indicates that the habitat created by forest edges supports unique macromoth assemblages. Moreover, the macromoth assemblage in this habitat is rich and abundant as compared to the adjacent habitats. This has important implications for the maintenance of biodiversity and the provisioning of ecosystem services in the boreal, as well as forestry in the context of natural disturbance emulation.