Ecological features of plant communities containing Globularia bisnagarica L. in the Middle and Lower Volga Region

The present article investigates the plant communities of the Middle and Lower Volga region that contain Globularia bisnagarica L. (G. punctate Lapeyr., G. willkommii Nylan) – the species listed in the Red Book of the Russian Federation, the Republic of Bashkortostan, the Republic of Tatarstan, the Stavropol Krai, the Orenburg, Samara, Saratov and Ulyanovsk Province, and Kazakhstan. The paper provides the geo-botanical description as well as the ecological and coenotic properties of 13 plant communities located in the Middle and Lower Volga region (the Ulyanovsk, Saratov and Samara Provinces). It is shown that the studied communities are confined to the elevated elements of relief where soil erosion usually takes place and bedrock gets exposed. Most communities grow on proto-soils – namely, carbonated. In general, the communities under study include 141 vascular species. In individual communities, the total projective cover fluctuates from 25 to 90%; the number of species varies from 29 to 43. Furthermore, the study subdivides the communities containing G. bisnagarica into 10 types. The level of set similarity is rather low (IBD is mere 19.5%). Finally, based on the bio-morphological content, most species in the studied communities are classified as hemicryptophytes, which is typical for the moderately cold zones of the Holarctic realm. Among trophomorphs, mesotrophs are predominant (62%); while oligotrophs are a third as many.