Calciphyte steppe communities of the Seim River basin (within the limits of the Kursk Region)

The paper deals with the calciphyte steppe com­munities of the Seim River basin (Kursk Region), represented by the two new associations, Asperulo cynanchicae—Onobrychidietum arenariae ass. nov. and Achilleo collinae—Astragaletum onobrychis ass. nov., which form a new suballiance Bupleuro falcati—Gyp­sophi­lenion altissimae suball. nov. The diagnostic spe­cies of this unit are Anthemis tinctoria, Bupleurum falcatum, Campanula sibirica, Centaurea pseudomacu­­losa, Gypso­phila altissima, Jurinea arachnoidea, Poa compressa, Polygala sibirica, Salvia stepposa, S. ver­­ticillata, Viola rupestris and the ass. Asperulo-Ono­brychidietum is selected as its holotype. The suballiance comprises calciphyte steppe communities on Cre­ta­ceous marl outcrops in both steep and gentle southern and south-eastern gully slopes, characterized by the combination of calciphyte petrophytes and typical steppe plants. According to the diagnostic species set, the unit is referred to the alliance Festucion valesiacae Klika 1931. The studied communities may be treated as a variant of the petrophytic calciphyte steppes distributed in the south-western part of the Middle-Russian Upland.