The pattern of high plant diversity of Neotropical inselbergs: highlighting endemic, threatened and unique species

Understanding how multiple drivers shape plant community diversity across environmental gradients is one of the most important issues in plant ecology and biodiversity conservation. We aimed to analyse plant community structure and diversity in four inselbergs in Espirito Santo State, Brazil. We evaluated species diversity, floristic composition and similarity, phytosociological structure, occurrence, and conservation status of rupicolous flora in the inselberg communities. We used field expeditions and plant inventory data from 370 sampling units. We estimated floristic similarity and compared diversity indexes among inselbergs. We observed marked differences in community structure and diversity among inselbergs, where the southern region had the highest number of taxa and higher values of diversity indices. There were also notable differences in floristic composition and phytosociological structure, with a decrease in similarity as geographical distance increased. This finding demonstrated the existence of differences in the patterns of dominance and vegetation cover along the latitudinal gradient, as well as differences in endemic, threatened, and exclusive species, and represents a first step toward establishing criteria for biodiversity conservation for inselbergs in Espirito Santo State.