Effects of landscape structure on butterfly species richness and abundance in agricultural landscapes in eastern Ontario, Canada

Abstract

The conversion of land from natural areas to agricultural land-use results in changes in landscape pattern, which may affect the presence and distribution of species within these landscapes. Agricultural landscapes with more cover types (higher compositional heterogeneity) should provide more species with the resources necessary to survive. Landscapes with more complex spatial patterns (higher configurational heterogeneity) should allow organisms to obtain resources more efficiently. The objective of this study was to test the predictions that butterfly richness and abundance will be higher in more heterogeneous agricultural landscapes, where heterogeneity was measured by the number of patch types (patch richness) and the number of patches (patch density) in the landscape. Butterflies were sampled at the centers of 40 landscapes in eastern Ontario, Canada. The landscape variables patch density, patch richness and the amount of butterfly habitat were measured for each landscape at multiple spatial scales. Butterfly species richness was higher in landscapes with more butterfly habitat and higher patch density. In contrast, butterfly abundance was higher in landscapes with lower patch richness. Our results suggest that agricultural and environmental policies aimed at maintaining butterfly diversity and abundance should provide incentives for farmers to maintain landscapes with higher configurational heterogeneity and more butterfly habitat.