Multi-scale effects of farmland management on dragonfly and damselfly assemblages of farmland ponds
Raebel EM., Merckx T., Feber RE., Riordan P., Thompson DJ., MacDonald DW.
Agricultural intensification has contributed to severe declines in odonate (dragonfly and damselfly) populations. Odonates require healthy waterbodies for their larval stages and resource-rich terrestrial landscapes as adults. As such, farmland management at both local and larger landscape scales may be needed to reverse population declines. We sampled odonate adults and exuviae from lowland farmland ponds in England, to investigate relationships between odonate species richness and surrounding land-use. The more mobile dragonflies (Anisoptera) were influenced most strongly by landscape variables at the largest scale (i.e. 1600. m radius), while less mobile damselflies (Zygoptera) were affected by variables at more local scales (i.e. 100/400. m radii). A greater number of landscape variables affected exuvial species richness compared to adult species richness. Exuvial species richness was higher when 2. m wide cross-compliance buffer strips around ponds were present. However, no ponds in the study had buffer strips that were established through England's basic agri-environment scheme (Entry Level Scheme: ELS) agreements, and we observed a negative relationship between ELS area and exuvial species richness. Exuvial species richness increased with the amount of water, but not the number of ponds, in the landscape surrounding a focal pond. The observed odonate responses to local and surrounding land-use lend support to the development of agri-environment scheme policies that encourage landscape-scale, as well as local, scheme implementation and management. We predict that both landscape-scale and quality-targeted management of farmland ponds would benefit odonates, irrespective of mobility level and life-stage. © 2012 Elsevier B.V.