Synergy between nature reserves and agri-environmental schemes in enhancing ditch bank target species plant diversity

The issue of what conservation strategies to apply in agricultural landscape for the most effective protection of biodiversity has been debated for some years. The creation and maintenance of nature reserves is often hampered by both ecological and economic factors, while the ecological effectiveness of agri-environment schemes (AES) is still being queried. Our study examined how the spatial pattern of nature reserves and AES affects the diversity of 25 target species of conservation interest in ditch banks and how this information might be used to develop a strategy resulting in synergy between protected areas and enhanced matrix quality. We studied target species plant diversity on 92 ditch banks under AES and on 102 banks not under such a regime; all of them running parallel to nature reserves. We compared the results with those obtained from a previous study which focused on ditch banks running transverse. On non-AES ditch banks running parallel to nature reserves, there was a significant decline in species richness with increasing distance from the nature reserve while this was not the case for AES ditch banks. The effect of AES differed between the two directions, with a significant effect beyond 200 m in the parallel direction and within 200 m in the transverse direction. Our results indicate that synergy between nature reserves and AES can enhance plant diversity and, since the AES effect was different in different direction due to wind direction and nitrogen input to adjacent fields, location of AES should be chosen carefully. (C) 2010 Elsevier Ltd. All rights reserved.