Fragments of subdesert vegetation in the Mediterranean Region: the Periploca angustifolia maquis (Periplocion angustifoliae, Quercetea ilicis) in Sicily

The paper presents the results of a phytogeographic, ecological, phytosociological, and management-oriented study on the maquis vegetation dominated by Periploca angustifolia (class Quercetea ilicis ) occurring along of southern coast of mainland Sicily. The species is a South-Mediterranean shrub, previously known in Europe only from some small islands surrounding Sicily (Linosa, Lampedusa, Pantelleria, and the Aegadian, and the Maltese Archipelagos), as well as from southeastern Spain and the Aegean islands of Crete, Khrisi, and Gavdos. Along with providing an updated overview of the species’ distribution, the study explores the historical reasons for its presence in Sicily, where it is part of a diverse group of biogeographically related species mainly found along the southern coasts. This further supports the hypothesis of connection routes contracted with North Africa during the drying of the Mediterranean in the Messinian period. Based on a synoptic comparison with similar associations present in the central-Mediterranean, the plant community investigated is proposed as a new syntaxon (association Asparago albi–Periplocetum angustifoliae ass. nov.), framed within the alliance Periplocion angustifoliae (order Pistacio–Rhamnetalia alaterni ). Its role as a vicariant association with respect to the association Periploco angustifoliae–Euphorbietum dendroidis (occurring on the small islands of the Sicilian Channel) is also discussed, together with floristic, synecological, syndynamic, and conservation data. Finally, issues concerning afforestation with alien species—often carried out on a large scale throughout the Mediterranean area—are discussed, as such interventions may sometimes negatively affect ecosystems typical of endemic or particularly rare species. This is precisely the case of Periploca angustifolia in the study area, whose residual population had been brought to the brink of extinction by conifer plantations, leading to the alteration and consequent disappearance of its habitats.