ABSTRACTHabitat loss and fragmentation causes decline of insect populations. Odonata (both dragonflies and damselflies) are especially threatened, because they are notably influenced by both aquatic and terrestrial environment. We explored the relative importance of local and landscape variables for Odonata assemblages (species richness, assemblage composition, population abundance) revealing differences in the sensitivity of Zygoptera and Anisoptera on the selected variables. Our study took two years and was placed along 11 lowland watercourses. We sampled the specimens using 500 m long transects from May to September. Landscape variables (length of watercourses, forest patch proportion, and farmland patch size) were calculated at three scales to better account for fragmentation. Our findings show that local variables influence damselflies, but dragonflies are more sensitive to landscape variables. Damselfly’s diversity decreased with the increasing macrovegetation cover, while dragonfly’s diversity decreased with the increasing degree of land use intensification, but increased with the length of watercourses. Our findings, both on local and landscape scales demonstrated the importance of terrestrial environment on Odonata. Based on our findings we stress the importance of partial watercourse clearing, and maintenance of traditional farm management based on small parcel farming near watercourses to maintain diverse and healthy Odonata assemblages.
The relative importance of biotic and abiotic determinants of temporal occupancy for avian species in North America
