Site dependence of local variations in taxonomic and functional diversity of plant communities in semi-natural dry grasslands.

As diversity is the result of a multitude of processes that shape communities, the adoption of a multi-faceted approach is fundamental to assessing the biodiversity of grassland habitats. Moreover, considering different components of diversity, such as alpha and beta, is crucial to properly distinguish small- (e.g., habitat and biotic filters) and broad-scale (e.g., dispersal limitation) processes acting on communities. Accordingly, we adopted a broad approach, taking into account alpha and beta diversity components of plant diversity to assess whether small-scale changes in grassland biodiversity are site-dependent. Additionally, such framework has been improved addressing a multi-faceted perspective, thus considering both taxonomic and functional diversity. Our results showed that plant α-diversity differed taxonomically and functionally only between the two sites, while β-diversity also showed local functional differentiation. Furthermore, we demonstrated that while taxonomic β-diversity is mostly due to species turnover, functional β-diversity is equally due to turnover and nestedness.