In Switzerland, biodiversity promotion areas or BPAs (i.e. land under Swiss agri-environment schemes) account for around 15 % of the utilised agricultural area. While the main objective of BPAs is to promote farmland biodiversity, their effectiveness remains limited, in particular as regards the incidence of invertebrates in the lowlands. In this study, the mowing regime of lowland BPA hay meadows was manipulated to measure the impact on biodiversity. Results show that the abundance of invertebrates increases, – sometimes massively – when the first mowing date is delayed by one month (i.e. from mid-June to mid-July) and/or when a refuge is left uncut at each mowing event on 10 to 20 % of the meadow area. In addition, both of these alternative mowing regimes also increase the species richness of some invertebrate taxa. As regards vegetation, there was no sign of change after five years. These findings demonstrate both the short-term (i.e. over a season) and longterm (cumulative, i.e. from one year to the next) beneficial role of delaying mowing and leaving uncut refuges for the sake of biodiversity.
Alternative mowing regimes to favour meadow biodiversity