Big Data and vegetation resurvey to support plant biodiversity research on Mediterranean islands

The Mediterranean region is one of the World’s biodiversity hotspots, known for its considerable species diversity and island richness. Biological communities on Mediterranean islands have been largely studied, especially for their vascular plant diversity. However, several data lacks critically limit research possibilities, in particular for ecological assessments at the basin scale. First, imprecise information on the number and location of medium and small Mediterranean islands is available. Moreover, a comprehensive database of island floras is still missing, despite dozens of studies have been published on this topic in the last decades. What is more, it is not known how global phenomena (e.g., climatic change, human driven land use change, alien species spread) are affecting plant communities of Small Mediterranean islands. With this thesis, I started addressing these limitations in data availability. To increase spatial data availability, I presented the MEDIS database, the up-to-date largest collection of geographic and ecological information on Mediterranean islands, providing data for 2,217 islands larger than 0.01 km2 and 39 associated variables. To assess plant data availability for Mediterranean islands, I retrieved data from three large biodiversity databases and used MEDIS for data aggregation at island level. I found considerable discrepancies among the databases in terms of spatial and taxonomic coverage, highlighting the necessity to digitise already existing island floras, to create a comprehensive database of Mediterranean island floras. Finally, I built up a research team, which resurveyed 183 historic vegetation plots on 47 small islands. Data analysis suggests two slight ongoing processes: secondary succession after ceasing of previous human traditional management and slight ruderalisation of plant communities. This thesis provides a new practical tool (MEDIS) and evidence from Big Data analysis and vegetation resurvey, to support and guide future biodiversity research on Mediterranean islands.