GRASSLANDS MANAGEMENT AND BIODIVERSITY CONSERVATION: AN EXAMPLE WITH REFERENCE TO ABOVE GROUND ARTHROPOD COMMUNITIES IN LIGURIA (NW ITALY)

In 2016 the species richness of arthropod communities was investigated in two grasslands overlying limestone substrate in order to obtain management information useful for the conservation of biodiversity of a protected area within the Antola Regional Park in Liguria, North-Western Italy. During the summer season arthropods with different ecological and behavioural traits were collected using sweep nets, butterfly nets and pitfall traps from an extensive pasture in Bavastrelli and an irregularly mown, unfertilised meadow in Garaventa. Individual- and sample-based rarefaction analyses were performed to estimate the expected species richness detectable for each collection method. Concurrently, an expeditious study of the plant assemblages for both sites was also undertaken in order to characterize their central area and margins. Differences between the expected and observed number of arthropod species for the two study areas were influenced by collection methodology and associated statistical analysis; however, the Bavastrelli pasture resulted in higher values of species richness both in terms of the number of estimated and observed taxa and species. Plant species richness was slightly greater in Garaventa (totally 90 species, 63 of which in the core area) than in Bavastrelli (80 species overall, including 54 in the central part of the pasture) with a greater number of Festuco-Brometea species showing an evolutionary tendency towards more xeric formations. The observed herbaceous formations characteristic of the Molinio-Arrhenatheretea were richer in species of the Plantaginetalia majoris complex when animals grazed and trampled for longer periods. Also, there seems to be an inverse relationship between overall plant and arthropod species richness in the two study areas. Overall, these results highlight the importance of a middle-low level of grazing in maintaining high arthropod biodiversity level at a local scale and suggest the opportunity to diversify grassland management in order to increase, and conserve, the biodiversity on a larger scale.