Revisiting Pianosa (Italy): How vegetation of a small Mediterranean has changed in the last 15 years.

Resurveying historical vegetation plots has become a fundamental methodology in ecological research as it provides a unique opportunity to estimate vegetation and environmental changes over the past decades. The vegetation of Pianosa has been thorouhgly described by Foggi et al (2008), who carried out several vegetation relevés, and it has been resurveyed in spring 2023. The original methodology was followed and a total of 30 georeferenced vegetation plots revisited, ensuring a strong correspondence between the location of the old and the new sampling points. Moreover, the literature information has been complemented with personal feedback provided by the botanists that sampled the historical plots. The preliminary results a significant compositional shift for all the considered types of vegetation. The main processes which has been detected as responsible of such changes in species composition are: i) the spread of some alien species (e.g. Pinus halepensis) which colonised and drastically changed the physiognomy of some contexts (e.g. from garigues to woody stands of pine); ii) a significant encroachment of the grasslands by typical shrub species, with their transition from open areas with herbaceous species to Mediterranean maquis; iii) a decrease of the abundance of Jacobaea maritima and Mesembryanthemum nodiflorum in rocky cliff communities. Such changes in species composition of the vegetation have been also found, even stronger, at a functional level, and can be probably explained by the changes in vegetation physiognomy. These results are relevant for research on the main drivers of changes occurring in small island contexts and might provide pivotal information for the conservation of Tuscan Archipelago habitats.