Remnant habitat patches provide high value for a wide range of insect species in a timber plantation mosaic

Abstract

Species present in transformed landscapes utilise resources from either the transformed patches, natural patches, or both. Depending on the degree to which species are specialised, species-specific responses to landscape transformation is both varied and dynamic. Understanding species-specific responses across a landscape is therefore essential to make informed conservation decisions. We investigate how spillover of stenotopic, cultural, and ubiquitous insect species respond to the different edge combinations present in a timber plantation mosaic. We use a multi-taxon approach, sampling two distinct insect assemblages (ground and foliage) across four different biotopes in a grassland-forest-plantation landscape in the Midlands of KwaZulu-Natal, South Africa, which forms part of the Maputaland-Pondoland-Albany biodiversity hotspot. We show that in this landscape, ecological networks consisting of natural grassland and forest supported high insect diversity in both ground and foliage assemblages. The foliage assemblage displayed stronger responses to the different biotope combinations than the ground assemblage. There was remarkably little spillover of habitat specialist species of either the ground or foliage assemblages from grassland or forest into the plantation stands. The few species associated with plantation stands (cultural species) had consistent levels of spillover across different types of plantation blocks, but not into the natural areas. Natural biotopes in this landscape conserved many habitat specialists, whereas plantations maintained low levels of diversity. Thus, we recommend that conservation practitioners consider the fidelity and spillover of the species present in the local landscape before designing conservation plans in these dynamic production landscapes.