Extinction debt in naturally contracting mountain meadows in the Pacific Northwest, USA: varying responses of plants and feeding guilds of nocturnal moths

Abstract

Fire suppression and climate change are leading to habitat fragmentation in temperate montane meadows across the globe, raising concerns about biodiversity loss. Restoration strategies may depend on the rate and nature of species response to habitat loss. We examined the effects of habitat loss and fragmentation on plants and nocturnal moths in natural montane meadows in the western Cascades, Oregon, USA, using generalized additive mixed models, non-metric multidimensional scaling, and multiple response permutation procedure. Historic (1949) rather than current (2005) meadow size explained species richness of herbaceous plants and herb-feeding moths and meadow plant community structure, indicating that loss of meadow species may be delayed by many decades following loss of meadow habitat, resulting in an extinction debt. In contrast, abundance of herb-feeding moths and species richness and abundance of woody plant-feeding moths were related to recent meadow configuration: as meadows are invaded by woody plants, abundance of meadow species declines, and woody plants and associated moths increase. Despite decades of fire suppression and climate change, montane meadows in many temperate mountain landscapes may still be amenable to restoration.