Rare communities with Thymus zheguliensis in the Zhiguli mountains

The analysis geobotanical of the plant communities with the participation of the endemic Thymus zheguliensis of the Zhiguli Mountains was carried out using the method by Braun-Blanquet. The database of relevés of the Middle Volga was used for this analysis. Data processing was carried out using JUICE program packages. In the cluster analysis of 115 relevés, 3 groups were formed. The species composition and characteristics of ecotopes in clusters differ. The results of DCA-ordination of three clusters with the participation of Thymus zheguliensis are presented. A reliable correlation was established between the position of these groups in the space of the DCA axes and the values of D.N. Tsyganov's environmental indicators (climatic and soil). Diagnostic, constant species have been established in the studied phytocenoses. Rare and protected species are noted. Plant communities with the participation of Thymus zheguliensis occupy small areas of rocky slopes of Zhiguli, fasten the substrate, slowing down the processes of erosion. Further study of them will make it possible to classify the vegetation and add syntaxons of Samara Onion to the prodromus.