Wild Seed Harvesting at Mountainous Species-Rich Grassland in Calcareous Italian Alps

Wild harvesting is an efficient option for supplying seed to be used for restoring semi-natural grasslands. Several methods are currently used to implement wild harvesting, but few controlled experiments have investigated its efficiency regarding seed amount and number of species collected. A harvesting trial was conducted in a species-rich, low-productivity grassland of the calcareous Italian Alps (1030 m a.s.l.). Three mechanical methods were tested in three replications using a completely randomized block design: green hay (GH), dry hay (DH), and seed stripping (SS). The number of fertile shoots, mature seeds, and species collected was recorded and compared to the standing seed yield (SSY). GH, DH, and SS harvested approximately 84%, 70%, and 29% of SSY respectively. Forbs were harvested more efficiently than grasses in all methods but in most cases at very low seed amounts per m2 due to their low seed density for SSY. No significant difference among methods was found for the number of species collected as mature seeds, but SS, implemented on larger plots, tended to collect more forb species. Comparing the results with those of other experiments demonstrated that the relatively cool temperature of the seed maturation period at the mountain site favored stronger seed retention and therefore increased the GH and DH efficiency but decreased the SS efficiency. In cool mountain areas, wild harvesting from forb-rich grasslands should be more successful by SS implemented on wide areas and several times over the vegetative season. In less species-rich grassland, GH and DH can efficiently collect high seed amounts of the fewer species present, even if implemented over smaller areas.