Moderate grazing impacts on insect-flower interactions in grasslands in a biodiversity hotspot

Abstract

Transformation of natural landscapes is the leading cause of global biodiversity decline. This is often exacerbated through anthropogenic activities that result in the alteration of natural ecosystem. Displacement of local species is characteristics of this process and this is of negative consequence especially for species in mutualism. In this study, how grazing and mowing activities influence flower-insect interactions and communities of interacting partners was assessed. Insect-flower interactions were sampled in four replicates, each of grazed and mowed grasslands in a moderately disturbed ecosystem. Mean distance to natural areas was determined during the study to assess the buffering effect of these natural areas on insect-flower interactions in the local habitats. Flower visiting insect species richness and abundance were not significantly different between grazed and mowed grasslands; however, flowering plants richness and abundance were higher in grazed grasslands. Mean number of interactions was also higher in grazed grassland as compared to mowed. Furthermore, mean number of interactions reduced with increase in distance from the forest. This study showed the importance of natural habitat as a refuge for displaced flower-visiting insects from disturbed areas in a transformed landscape. Mutualistic partners in interaction tend to be resilient to moderate disturbance such as grazing in this study; however, an increase in the intensity of disturbance above the moderate threshold may result in a breakdown of interaction networks.