Seed content and conservation evaluation of hay material of fen grasslands

Summary Hay transfer is one possible method to restore biodiversity in degenerated fen grasslands. The suitable abiotic and biotic conditions of the acceptor site as well as the seed content and its viability of applied hay material are main factors affecting the success of this method. In the present study we investigated the species composition of the established vegetation and the seed content of the hay for five species-rich fen grassland communities in Northern Germany in order to choose the optimal donor site for a planned hay transfer. We calculated a rarity-weighted fen grassland species score to compare and evaluate the investigated communities with regard to the conservation of regionally rare and characteristic fen grassland species. Species number in the aboveground vegetation varied between 29 and 41 species per 25 m 2 plot. Between 40% and 70% of the species occurring in the aboveground vegetation were represented as seeds in the hay. A cluster analysis showed a high similarity between the aboveground vegetation and the hay material, especially for one particular community. The number of seeds ranged from about 2000 to 12,000 per square metre. The viability of the seeds of both herbs and sedges was high (approximately 80%) whereas the viability of grasses was only about 40%. Due to dormancy the germination percentage was much lower in all groups (20–50%). The results of the rarity-weighted fen grassland species score of the hays’ seed content, and of the relation between aboveground vegetation and species composition of the hay enabled a decision when choosing a particular community (low productive sedge-dominated fen meadow) as a donor site for hay transfer.