The conservation of arable plants on cereal field margins: An assessment of new agri-environment scheme options in England, UK

Agri-environment (AE) schemes aim to arrest declines in arable biodiversity through cereal field margin management options. We evaluated the effectiveness of uncropped cultivated margins (UCM), spring fallow (SF) and cropped conservation headlands with (CH) or without fertiliser inputs (CH(NF)) in sustaining plant species diversity and rare species, in England, UK. Sampling was stratified at 1 m, 3 m and 5 m from the edge of the margin and in eight regions to assess environmental influences on species composition. Species diversity, including rare species, was highest on UCM, followed by SF and CH(NF) margins. Diversity was generally lower on cropped margins due to competition from the crop. Fertilised CH margins were the least diverse option and were similar to cereal crop controls. Species diversity was greatest at the edge of all except UCM margins and there was a strong latitudinal decline in overall diversity and rare species. AE management accounted for more variation in species composition than habitat context, physical/climatic variables, soil properties or region. At cropped sites, there was overlap between margin type and other variables but soil properties explained less variation. At uncropped sites, management and physical/climate variables explained most variation but soil properties were more important than at cropped sites. These findings confirm that AE schemes are effective in conserving arable plants, including rare species, across a variety of landscape types. More precise geographical targeting, improved control of competitive species and research on the habitat requirements of rare species will improve the overall efficacy of schemes in the future.