Petrophytic feather-grass and thyme steppes in the south-east of the Kursk Region (within the limits of the Oskol river basin)

Abstract

The paper deals with 2 new associations, represen­ting the petrophytic steppe communities described from the Oskol river basin (Kursk Region), Gypsophilo altissimae—Stipetum capillatae ass. nov. and Carici humilis—Thymetum calcarei ass. nov. First asso­ciation is included into the alliance Astragalo-Stipion Knapp 1944. The communities of this alliance are represented by the most xerophytic variant of the feather-grass steppes of Kursk Region and they are characterized by the combination of obligatory calci­philous and typical steppe plants. Second association is included into the alliance Centaureo carbonatae—Koelerion talievii Romaschenko, Didukh et Solomakha 1996 of the order Festucetalia valesiacae Br.-Bl. et Tx. 1943. The alliance comprises petrophytic thyme steppe communities on chalk outcrops (mostly in the southern slopes) and on hill’s tops. The commu­nities are characterized by the dominance of obligatory calciphilous and petrophilous steppe species. The communities of this alliance are widely spread in the Oskol River basin in the southern part of the Middle-Russian Upland.