The synecology of endemic relict species Ramonda serbica (Gesneriaceae)

The article presents the results of a study of the plant communities of Ramonda serbica, primarily intended to increase knowledge of their species and syntaxonomic diversity. The dataset included 204 vegetation plots (relevés) of the two Balkan Ramondas (R. serbica and R. nathaliae), 174 digitised from published literature sources and 30 new ones from field sampling of R. serbica in Montenegro and North Macedonia. Nineteen associations and subassociations of R. serbica were identified, using hierarchical cluster analysis (the Sørensen index as a distance measure and the Flexible Beta method, ß −0.25). Three associations (Micromerio julianae-Ramondetum serbicae, Hylocomio splendentis-Ramondetum serbicae, Neckero pumillae-Ramondetum serbicae), three subassociations (Micromerio julianae-Ramondetum serbicae subass. allosoretosum persicae, Ceterachi officinarum-Ramondetum serbicae subass. festucetosum dalmaticae and subass. hylotelephietosum maximi) and one alliance Exsertotheco crispae-Ramondion serbicae are described as new. Both hierarchical cluster analysis and non-metric multidimensional scaling ordination support the distinction of 3 chorological/ecological groups of R. serbica communities: Adriatic-Ionian (xerophilous), Moesian (xero and mesophilous communities) and Illyrian-Scardo-Pindic (hygromesophilous). Communities of the Adriatic-Ionian cluster belongs to alliances Edraianthion, Centaureo cuspidatae-Portenschagillion ramosissimae and Campanulion versicoloris, of the Moesian one to Edraiantho graminifolii-Erysimion comati, and the Illyrian-Scardo-Pindic one to novel alliance Exsertotheco crispae-Ramondion serbicae.