No need for grazing exclusion - Sheep grazing supports grassland recovery even from the early successional stages

Availability and dispersal of target plant propagules and applied management techniques can considerably affect the success of grassland restoration. In our study we explored the effect of sheep grazing on plant species composition of an early staged recovering grassland, which developed on newly created soil surfaces. We recorded the presence and cover of vascular plant species in 17 grazed and 6 ungrazed plots during three consecutive years after the restoration of a landfill in southern Italy. A DCA ordination based on species percentage cover was calculated to assess the species composition of the plots in the three years. Plant assemblages were compared to adjacent reference grassland in terms of species composition and cover of functional groups based on their role (i.e. target species or weeds) and their seed dispersal potential (i.e. high or low epizoochorous ranking index). For each parameter, Relative Response Indices (RRIs) were calculated to assess the relationship between the vegetation characteristics of the restored areas and the reference grassland. The DCA ordination of plant communities in the restored area revealed gradients of increasing similarity to reference grassland as a function of successional age and grazing. For most of the considered vegetation characteristics, RRIs in restored grassland became more similar to the reference grassland with increasing successional age and under grazed conditions. Besides underlining the role of passive restoration in supporting effective grassland recovery, our results revealed that extensive sheep grazing even from the early successional stages can improve target species dispersal and establishment, and enhance grassland restoration. Our results suggest that grazing can improve the feasibility and sustainability of restoration projects by saving costs of fence installation and providing forage for local animal husbandry.