Plant Diversity and Grassland Naturalness of Differently Managed Urban Areas of Torino (NW Italy)

The interest in urban grassland management has markedly increased over the last years, due to its essential role for biodiversity conservation and ecosystem service provision. In the metropolitan area of Torino, we compared plant species richness and habitat naturalness of urban grasslands subjected to three cutting regimes (characterized by one, four, and eight cuttings per year, respectively). Habitat naturalness was assessed using a phytosociological approach, considering the total number and percentage cover of species belonging to three different vegetation groups: i) annual ruderal, ii) perennial ruderal, and iii) semi-natural grassland species. The one-cutting regime negatively affected both plant species diversity and habitat naturalness, since it favoured the highest cover of ruderal species, which reduced semi-natural grassland species cover. Conversely, the four-cutting regime showed comparable results to the eight-cutting regime, with higher species richness and Shannon diversity index values than the one-cutting regime. Moreover, under both regimes, the highest values for the total number and percentage cover of semi-natural grassland species were detected. Consequently, we suggest the four-cutting regime as the best grassland urban management option, thanks to its higher benefit-cost ratio.