Changes in the species composition and conservation value of limestone grasslands in Northern Switzerland after 22 years of contrasting managements

Maintain species-rich, semi-natural grassland

A replicated study of different management regimes at two dry limestone grassland sites over 23 years in Switzerland (Köhler et al. 2005) found that compared to traditional management, alternative management regimes resulted in greater changes in plant species composition and abundance. Changes were most evident 12 years after the start and were continuing even after 22 years. By the end of the study at one site, the number of species had declined in the following order compared to plots under traditional management (annual mowing in July; 50 species): mowing annually in October (93% of species in traditionally managed plots), mowing every second year in July (90%), mowing every 5th year in July (79%), annual controlled burning February-March (79%) and abandoned (70%). At the other site, species number did not tend to differ with management (85-120% of traditionally managed plots). Cover of specific species tended to differ with management regime at both sites. Plots with mowing every second year in July, followed by mowing annually in October were the most similar in composition to traditional management. The six management regimes were investigated with three replicate plots (5 x 10 m) at each site from 1977 to 2001. Cuttings were removed immediately. Species composition was sampled 4-6 times at each site 1977-1996. The inner 4 x 9 m of each plot was also surveyed at both sites in May, June and September in 1997-1999.