Abstract
Nine hundred and eight-nine relevés from calcareous petrophytic steppes in Ukraine and its adjacent territories were assessed with the help of expert systems to determine the syntaxonomic affiliation of the plant communities at class and order levels. At least 488 relevés belonging to the class Festuco-Brometea were analyzed using the TWINSPAN algorithm, and 8 distinctive clusters were obtained, recognized as alliances of the order Stipo pulcherrimae-Festucetalia pallentis. A new alliance, Bromopsido cappadocicae-Asphodelinion tauricae, was ascribed to the Crimean Mountains and the presence of two alliances, Diantho lumnitzeri-Seslerion albicantis and Genisto tetragonae-Seselion peucedanifoliae, was confirmed as new for this vegetation in Ukraine. Unlike in the Pannonian Basin, Bromo pannonici-Festucion csikhegyensis alliance communities mentioned in the literature do not occur in Ukraine. Centaureo carbonatae-Koelerion talievii has been provisionally transferred from Festucetalia valesiacae to the order Stipo pulcherrimae-Festucetalia pallentis. Furthermore, we distinguished alliances by their geographic locations and their climatic (thermoregime, cryoregime, light in communities) and edaphic (carbonate content, salinity, and acidity) features.