The response of moth communities to ecosystem restoration

Abstract

Ecosystems and biodiversity worldwide have been heavily degraded as a result of anthropogenic activity and the need for the restoration of these degraded ecosystems is increasingly realised. Understanding how species respond to ecosystem restoration is important for assessing whether actions taken are achieving the restoration objectives. This study assessed the response of moth communities to forest ecosystem restoration in a fenced ecosanctuary in the South Island of New Zealand. The predator-proof fence excludes mammalian predators and browsers and thereby facilitates two primary restoration processes: recovery of populations of native fauna, and regeneration of vegetation allowing forest succession to take place. The aim of the study was to determine the relative importance of mammalian pest control, habitat succession and season on moth community structure and composition Moths were sampled in three forest habitat types (early, mid, late-succession), inside and outside of the fenced ecosanctuary once per month over seven months. Environmental covariate data on the vegetation, small-mammals, climate and topography were collected at each sampling location. Indices of moth community structure and composition were analysed in relation to mammalian pest control, habitat successional stage, the interactive effect of these factors, and in relation to season. The predator-proof fence had a significant effect on moth abundance and species richness; both were significantly higher inside the ecosanctuary than outside. However, the mid-successional forest habitats had significantly higher moth abundance, richness and diversity than either early or late-successional communities. This strong interaction effect indicates mammalian pest control may not affect moth community structure equally along a forest successional gradient. Moth community composition was closely associated with habitat successional stage but showed no relationship with whether samples were collected inside or outside of the ecosanctuary. If left unaccounted for, however, natural seasonal trends in moth communities largely mask any underlying spatial drivers. Accounting for temporal variation in sampling schemes or analyses is crucial for understanding the response of moth communities to ecosystem restoration and other environmental drivers. These findings suggest that moth communities respond strongly to ecosystem restoration, hinting at their potential for use as indicators of ecosystem change.