Grassland restoration at a graded ski slope: Effects of propagation material and fertilisation on plant cover and vegetation

The increasing anthropisation of mountain regions is a cause of soil degradation, which needs to be addressed. Conventional methods of ski slope revegetation often fail to stabilise the soil and recover natural vegetation. To test alternative methods to create a persistent, biodiversityfriendly plant cover, different sowing (site-adapted native propagation materials vs. forage cultivars vs. no sowing) and fertilisation treatments were compared over nine years at a graded ski slope. Because of the gravelly soil, the ninth-year plant cover was only 65%, which was sufficient to prevent erosion. All native propagation materials were equally efficient at recreating a semi-natural grassland. Except for Festuca rubra, the forage cultivars did not persist. However, native volunteer species from close natural ecosystems efficiently colonised plots sown with forage cultivars and plots that were not sown. This resulted in a lower plant cover but a high similarity to the surrounding vegetation. Fertilisation had a positive but transient effect on plant cover and a little negative effect on species richness. High-altitude sites with gravelly soils should be revegetated with native propagation materials. Using forage cultivars can attain a persistent plant cover only if the sown non-persistent cultivars are replaced by the species arriving from nearby surrounding vegetation.