Diachronic Analysis of the Floristic Diversity of the Special Area of Conservation (SAC) “Bosco di Santo Pietro” (South-Eastern Sicily): A Mediterranean Biodiversity Hotspot

This study presents a complete and updated checklist of the vascular flora of the SAC "Bosco di Santo Pietro", an important natural area located in south-eastern Sicily. Through an integrated approach combining field research, analysis of historical herbariums and a literature review, 583 taxa belonging to 78 families and 339 genera were identified. A comparison with an older floristic list of the Santo Pietro Forest dating back to 1889 highlights some significant changes, such as a decrease in several hygrophilous and nemoral species probably due to climate change and habitat degradation. In particular, our diachronic analysis reveals the disappearance of 178 taxa and the persistence of 199 taxa representing 47% and 53% of the 377 taxa listed in the first inventory, respectively. From the study of the Ellenberg indicator of the two lists, lower values of L and T and higher values of M and N emerge in the older flora, testifying to the significant environmental modifications for more than a century of this Sicilian and Mediterranean hotspot.