Rare plant communities of the Vis Archipelago (Croatia)

The Dalmatian coast (Croatia) represents the second largest Archipelago within the Mediterranean area and contributes considerably to the Mediterranean biodiversity. The islands of the Vis Archipelago, in particular, contain an exceptional richness of endemic and rare plant taxa. The aim of this paper is to provide a phytosociological description of the rare plants communities occurring in the Vis Archipelago and define their syntaxonomic position in the Mediterranean context. A data-set consisting of 90 phytosociological relevés was subjected to cluster analysis (Ward's method on a Chord distance matrix) and non-metric multidimensional scaling ordination. The Indicator Species Analysis was used to identify the diagnostic taxa of the main clusters of relevés. The occurrence of the Anthyllidion barbae-jovis in Croatia was documented with new relevés. Four new associations of the Crithmo-Staticetalia and four further new ones of the Helichrysetalia italici were described for the first time. A endemic alliance to the Vis archipelago (Croatia) and Tremiti islands (Italy), Capparo orientalis-Aurinion leucadeae, was validated in order to include plant communities of coastal rocky cliffs which are not directly exposed to sea-borne salt-spray but are still under the influence of sea-born salt due to the intense offing storms, in the middle Adriatic. The results were discussed in the light of the European syntaxonomic framework of the EuroVegChecklist. Several syntaxonomic interpretative problems regarding the interface between the Helichrysetalia italici and the Centaureo-Campanuletalia have arisen and they have been only partially solved with the validation of the Capparo-Aurinion. New investigations are required on this topic.