Buffer zones maximize invertebrate conservation in a Biosphere Reserve

Abstract

Recent declines in invertebrates are linked to anthropogenic global change drivers thus land use planning that considers invertebrate conservation is necessary. Although most animals are invertebrates, conservation initiatives largely ignore these groups in part because of a paucity of studies addressing their diversity patterns. Biosphere Reserves provide an holistic approach to conservation planning. Here we explore the covariates that underlie beetle and spider diversity across the largest Biosphere Reserve in South Africa and use this model to predict compositional turnover across the reserve using Generalized Dissimilarity Modelling (GDM). We then use these patterns to assess the proportion of the ecological environments, scaled using beetle and spider assemblages, that is included in either core or buffer zones. The GDM model explained 53% of the variation in observed compositional turnover. Important local-scale drivers of turnover were leaf litter and organic content of the soil, while broad-scale co-variables were isothermality and mean diurnal range. Buffer zones increased conservation coverage by between 50 and 100%, depending on the planning scenario involved and complimented regional conservation plans. However, local conservation practices rarely reflect that of regional planning exercises, and initiatives should focus on monitoring compliance that considers both landscape and local processes. Conservation efforts should not only focus on core areas in Biosphere Reserves. Managing buffer zones must receive similar if not more attention due to the larger anthropogenic footprint.