The alpine scrubs and dwarf heaths of the Balkan Peninsula - an exceptional center of floristic richness and endemism

Alpine scrubs (Roso pendulinae-Pinetea mugo) and dwarf heaths (Loiseleurio procumbentis-Vaccinietea) are an exceptional assemblage of rich floristic units which contribute significantly to the overall diversity on the Balkan Peninsula. The main edificators of these types of habitats are mostly glacial relicts. Additionally, they are of the arctic, alpine, and boreal distribution types, which further emphasises their importance from the conservation point of view. We investigated their taxonomic richness, endemism, patterns of spatial distribution and diversification in the central Balkans as well as their coenotic composition using a comprehensive dataset (15,609 species occurrence data). The analyses were conducted at three hierarchical levels taking into account the ecological and geographic diversity of the alpine scrubs and dwarf heaths in the study area. The results obtained showed that in the alpine scrubs and dwarf heaths of the central Balkans 902 taxa (829 species and 73 subspecies) had been recorded, and that the proportion of endemics in these habitats is extremely high (ca. 22%). Our results further showed that in 180 randomly selected plots of medium size (? 10 and < 100 m2), the registered regional floristic richness for the unique sample size was 527 species, placing the alpine region of the Balkan Peninsula in second place among the richest alpine regions in the world. Moreover, significant regional differences in species composition were observed within the research area, with floristic richness and diversity increasing from north to south.