Effects of vineyard management on biotic homogenization of insect–flower interaction networks in the Cape Floristic Region biodiversity hotspot

Abstract

Plant and animal communities, as well as their interaction networks in agricultural landscapes, face threats of biotic homogenization due mostly to intensive management and cropland expansion. It is unclear whether agri-environmental schemes that promote environmentally friendly farming approaches can reduce the effects of these threats which cause reduction in regional (beta) diversity. Here, we examined biotic homogenization of insect–flower interactions in vineyards managed under agri-environmental schemes in the Cape Floristic Region (CFR). The interaction networks studied are of significant conservation value in the fragmented CFR agricultural landscape. Assessment was done using permutational distance-based test for homogeneity of multivariate dispersion to determine whether vineyards contributed to loss of diversity across the landscape through homogenization of their insect–flower interaction networks and flower visitor community. Vineyards did not show significant homogenization of interaction networks and flower-visitor community when compared to natural sites. Organic viticulture, integrated vineyard management and on-going protection of natural vegetation close to vineyards, as practiced in the CFR, are possibly contributing to the reduction in biotic homogenization observed here. Further vineyard expansion must however be prevented to avoid future biotic losses. These measures should be supported by all stakeholders in the conservation sector to achieve wine production while at the same time conserving the natural complement of biodiversity.