Grassland restoration on ex-arable land by transfer of brush-harvested propagules and green hay

Abstract

Effective restoration of meadows requires seeds of local provenance to preserve not only the species diversity but also the genetic identity of plant communities. We compared three different methods of seed harvesting from local meadow communities and assessed their efficiency in meadow restoration on ex-arable land. These methods were: brush harvesting once only, brush harvesting three times during a season, and green hay transfer. We observed the composition of species and functional traits of seed source meadows, sampled the three harvested seed mixtures and monitored plant communities restored on ex-arable land with this seed over the five following years. Green hay transfer was the method producing the highest amount of seeds (expressed as mass) and the highest number of species per unit of source-meadow area, followed by brush harvesting three times during one season and once only, respectively. This resulted in the highest establishment rate of species on ex-arable land in the green hay transfer method, followed by brush harvesting three times during one season and once only, respectively. Across all methods, species abundant in the seed mixture, having a low specific leaf area and a low capacity for lateral clonal spread, were the most successfully harvested and established ones. In the restored communities, mainly species number and cover of legumes but also of target meadow species increased with time, while ruderal weedy species decreased. Concerning species number and composition as well as trait spectrum, green hay transfer was the most successful method of restoration, resulting in a community most similar to the seed source meadow.