INFLUENCE OF SHRUBBY VEGETATION ON BIODIVERSITY IN A PASTURE OF THE APENNINES (CENTRAL ITALY).

The aim of this work was to investigate whether the encroachment of pastures by shrubs can lead to changes in biodiversity and quality of herbaceous vegetation. The research was carried out in a pasture located in a National Park in Central Italy. Twelve samples areas of 314 m2 representative of different density of woody species spread in a pasture were chosen. In each plot, the number of shrubby plants, height and crown width were recorded. Herbaceous vegetation was described according to Daget and Poissonet and different indexes were calculated to characterise the ecosystem diversity. Crataegus monogyna, Pyrus pyraster and Rosa canina were the most present among the shrubby species. Natural grassland was dominated by Cynosurus cristatus. Density of shrubs induced a significantly reduction in floristic richness of swards (r2=0.63++) but not in the quality. The lowest values of diversity index and evenness (respectively 2.37 and 0.84) were found in the areas with the highest density of woody plants. Results emphasise the necessity to control spreading of shrubs in order to avoid the loss of pastoral resources and to maintain the landscape biodiversity in protected areas.