The relative importance of grazing stock type and grazing intensity for conservation of mesotrophic 'old meadow' pasture

Unimproved neutral grasslands have declined in extent throughout Europe, especially in Britain. Some of the surviving fragments are managed as pasture but the grazing regime required to maintain their relict flora is unproven. We conducted a systematic review and analysed available data to ascertain the impact of grazing on species richness and the abundance of important plant species. We found the evidence base to be poor but with some potential for meaningful integration of existing datasets. Analyses of complementary datasets from Welsh mesotrophic grassland demonstrates that livestock type and vegetation height significantly impact on the plant community composition. However, the differences in species richness and forb abundance between livestock types are not ecologically significant, and grazing intensity appears to be more important than species of grazer. Managers must balance changes in bryophyte abundance, forb diversity and plant species richness to achieve tradeoffs appropriate to their conservation objectives. The poor evidence base necessitates flexible, site-based management and rigorous monitoring where grazing of important mesotrophic pastures is undertaken. Further evidence regarding interactions between grazing intensity and livestock type is noticeably lacking, precluding prediction regarding livestock type impacts at given stocking intensities. Lack of detailed knowledge of land-use history is a major impediment and there is little information regarding taxa other than vascular plants. (c) 2008 Elsevier GmbH. All rights reserved.