Restoration of sand grasslands by topsoil removal and self-greening

Gilhaus K., Vogt V., Hölzel N.

Zusammenfassung

Questions: Is topsoil removal in combination with year-round grazing a suitable method to restore and maintain nutrient-poor open sand grasslands and wet heaths on ex-arable land? Are there constraints in terms of animal nutrition? Location: Pastures on ex-arable land in pleistocene lowlands of Northwestern Germany, 120-160 m a.s.l. Methods: We sampled vegetation, soil nutrient status and above-ground biomass properties in 42 quadrats in a restored sand grassland and wet heath site and ten quadrats in an old sand grassland nearby. Data were analyzed using ordination, ANOVA and a generalized linear model. Results: Soil phosphorus and nitrogen were significantly reduced by topsoil removal to the level of target communities. A remarkably high number of typical and endangered sand grassland species established, presumably from the seed/spore bank. Compared to old, seasonally grazed sand grassland, higher species diversity could be observed after topsoil removal. Reasons may be the raised pH as a heritage of arable cultivation and the very open vegetation structures enhancing early successional species. Year-round grazing preserved open vegetation structures, but was not able to fully suppress birch encroachment in early stages of succession. Conclusions: Our study showed that combining topsoil removal, self-greening via recruitment from the seed/spore bank and subsequent year-round grazing might be particularly successful approaches for the restoration of endangered sand grasslands and wet heaths on ex-arable land. However, additional measures might be necessary to prevent undesired shrub encroachment in the first years after topsoil removal. Due to relatively low biomass quantity and quality of sand grasslands even in summer, we propose supplementary feeding in winter or a restriction to seasonal grazing to meet the requirements of animal welfare.