Field margins are important seminatural habitats in agro-ecosystems, but they can be negatively affected by pesticide inputs via direct overspray and spray drift. In Germany, risk mitigation measures (like buffer zones) to reduce pesticide inputs in terrestrial noncrop habitats do not have to be put in place by farmers next to narrow field margins (<3 m width). Because data on structure, size, and width of field margins are scarce, we identified field margins in 2 German agricultural landscapes (Rhineland-Palatinate [RLP], Brandenburg [BB]; 4000 ha each) using digital orthophotos and geographical information systems. In RLP, most of the field margins were less than 3 m wide (85% of margin length and 65% of the margin area), whereas in BB narrow field margins account for 45% of the margin length and 17% of the margin area. Hedgerows were only occasionally recorded. Hence, narrow grassy field margins can represent a large part of the available seminatural habitats adjoining agricultural sites and potentially act as corridors between further habitat patches. For this reason, these margins should be protected from pesticide inputs, at least in landscapes under intensive agricultural use. Field margins are also the main, so-called nontarget habitat protected by the terrestrial risk assessment for plants and arthropods. With many (narrow) margins not considered relevant for risk management, the current practice for protecting the biodiversity from negative effects of pesticides seems questionable. More data on field margin constitution in Germany and other European countries is necessary to critically assess the current practice of pesticide risk assessment and management on a larger scale.
Keywords: Field margin; Grass strip; Hedgerow; Pesticide; Risk management.
© 2014 SETAC.