Is the combination of topsoil replacement and inoculation with plant material an effective tool for the restoration of threatened sandy grassland?

Question: Is it possible to restore dry calcareous inland sand ecosystems with their characteristic plant community structure within a 4-yr period by means of combined abiotic-biotic techniques (topsoil replacement, inoculation with raked/mown plant material from target areas)? Location: Upper Rhine valley, Germany. Methods: Two 4-year experiments were carried out on former arable land, each in the proximity of a reference area bearing a similar complex of threatened sandy grasslands (experiment 1: fine-scale; experiment 2: landscape scale). In both experiments we used nutrient-poor deep-sand substrate (abiotic approach), raked/mown inoculation material from target areas and grazing as management tool (biotic and management approach). The vegetation of the restoration and donor areas was sampled once a year and analysed by non-metric multidimensional scaling (NMDS) ordination and target-species ratios. Mixed linear models were calculated to determine effects of grazing (experiment 1) and year (both experiments). Results: NMDS revealed a continuous development of the restored sites towards the corresponding donor sites. Similarly, target-species ratios of the restored sites tended towards the ratios of the donor sites. To date, grazing effects have mainly been structural: reduction of a carpet-forming pleurocarpous moss species and of litter. In addition, cover of target species in relation to total plant cover was significantly enhanced by grazing in the last two study years. Conclusions: The combination of nutrient-poor substrate, inoculation with raked/mown plant material and grazing proved to be a very effective restoration method for dry base-rich sand ecosystems. After 4 yr the restored plant communities serve as well-developed parts of a habitat network.