The study aimed to analyze vegetation data using a phytosociological method and to identify species composition and relationships between vegetation and environmental data in communities that include two threatened species (Dianthus pseudocrinitus Behrooz. & Joharchi and D. polylepis Bien. ex Boiss.) endemic to the montane steppes of Khorassan-Kopet Dagh floristic province in northeastern Iran. We sampled 75 vegetation plots in 15 sites where the endemic Dianthus species occur. In order to evaluate community characterization of the species, we investigated floristic composition, life-form spectrum and the phytogeography of the study sites. In all, 370 plant species were recorded, belonging to 184 genera in 45 families. Floristic analysis revealed that Hemicryptophytes are the dominant life-form in these habitats, and Iran-Turanian floristic elements contributed 74.5% of the total number of species. Classification analysis based on TWINSPAN showed a clear separation of the study sites based on Dianthus taxa, which was confirmed by detrended correspondence analysis (DCA). The results reflected the highly diverse flora at all Dianthus sites. Species composition and the distribution of vegetation groups were influenced by some environmental factors. Habitats for both species could be managed by a community ecological approach; our study provided a better knowledge of these communities’ ecological and floristic composition to enhance effective management and conservation of the threatened species.

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