Floristic regions of the Samur-Chirakhchay interfluve and Dzhufudag (Southern Dagestan) according to analysis of petrophyte species composition

Aim. To undertake floristic zoning of the Samur-Chirakhchay interfluve and Dzhufudag for the analysis of the species composition of petrophylic complexes. Material and Methods. A list of obligate petrophytes was compiled based on the results of processing the authors' own field collections and taking into account information from floristic reports and determinations. The assessment of similarity of species composition of petrophytes in the regions was carried out using the Jaccard (Kj) and S0rensen-Czekanowski (Ksc) coefficients. Results. A subdivision of the mountain area studied into 7 floristic regions was carried out, based on a comparison of floristic lists and the presence of endemic species. Conclusion. The tendency in petrophytes to isolation of species forms, arising from spatial isolation relating to habitat specificity, makes it possible to quite accurately draw boundaries corresponding to the natural boundaries of differentiation of floras.