| Abstrakt: |
Set-aside provides an opportunity to counteract recent declines in arable farmland biodiversity in the UK. Its recent widespread adoptionhas allowed its vegetation to be assessed from a national perspective. A botanical survey of 97 sites in England, stratified by intensivearable and mixed agriculture geographical regions, was carried out. Set-aside vegetation was established by natural regeneration or sown cover, and aged up to 9 years. Vegetation was recorded at each site from 30 quadrats located on transects running from the field boundary towards the field centre. Overall, cover was dominated by perennials and monocotyledons, with a large number of other species occurring atonly a few sites. Species functional types and individual species frequencies differed between region, establishment method (natural regeneration or sown cover), and site age. The mixed agriculture region had vegetation with characteristics more similar to grassland, whereasin the arable region succession remained at an earlier stage for longer. Sown species accounted for differences between establishment methods. Succession continued after 5 years, with increasing species richness, perennials and species characteristic of non-arable habitats. Species richness within sites declined with increasing distance from the field boundary. Variation between sites in plant community composition was not accounted for by generalized soil and site management data. Although overall botanical diversity was low, the development ofpermanent grassland habitats on non-rotational (long-term) set-asideis a realistic objective. This needs to be balanced against known benefits of rotational (short-term) set-aside. Variation between regions suggests that benefits to biodiversity will accrue at differing rates in arable and mixed farming landscapes. At a national scale, regional differences should be taken into account when implementing policyobjectives to optimise biodiversity benefits from set-aside. [ABSTRACT FROM AUTHOR] |
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