Assessing the value of agri-environment schemes for biodiversity: current status and opportunities

Jean-Yves Humbert
Conservation Biology, UniBE

In Switzerland, biodiversity promotion areas (BPA, i.e. land under Swiss agri-environment schemes) represent about 15% of the utilized agricultural area. While the main objective of BPA is to favour farmland biodiversity, their effectiveness remains modest, in particular as regards invertebrates and vertebrates occurring in the lowlands. In a first study, the mowing regime of lowland BPA hay meadows was manipulated to measure its impact on biodiversity. Results show that the population of invertebrates increases, sometimes massively, when the first mowing date is delayed by one month (from mid-June to mid-July) and/or when a refuge is left uncut at each mowing. As regards vegetation, it showed no sign of change after five years. In a second study we found out that if the proportion of BPA in the landscape increased from 5% to 15%, the butterfly species richness increased by 22% and that of birds by 10%. . For both taxonomic groups, the proportion and quality of BPA habitats was more important than their spatial configuration, including the distances between them.

back