Revisiting the small Mediterranean island of Pianosa (Italy).

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, allowing to evaluate how the vegetation dynamics are affected by anthropogenic factors, such as land-use change, invasion of alien species and climate change. Small islands are among the ecosystems in which the effect of these processes might be more detectable and less predictable. One of this case consists in Pianosa (Tuscan Archipelago, Italy), a small Mediterranean island in which such factors had incluences since the end of the 1990s. This research aimed to evaluate how different types of vegetation occurring on the island (rocky cliff, Mediterranean xeric grasslands, and scrub) changed in the last 15 years, both in terms of species and functional composition. The main processes which has been detected as responsible of such changes in species composition are: i) the spread of some alien species which colonised and drastically changed the physiognomy of some contexts; ii) a significant encroachment of the grasslands by typical shrub species, with their transition to maquis; iii) a decrease of the abundance of some typical rocky cliff species. Such changes in species composition have been recognized, even at higher degrees, at functional level, and is probably due to the changes in vegetation physiognomy.