The syntaxonomic diversity of vegetation of two localities in the southern part of the typical tundra subzone in the Gydansky Peninsula includes seven associations, three subassociations and eight variants. New associations (Tanaceto bipinnati–Salicetum polaris Khitun ass. nov. hoc loco, Calliergono cordifolii–Salicetum lanatae Khitun ass. nov. hoc loco), subassociations (Hierochloo alpinae–Hylocomietum splendentis asahinetosumchrysantae Khitun subass. nov. hoc loco, Carici rariflorae–Sphagnetum baltici sphagnetosum steerei Khitun subass. nov. hoc loco) and eight variants are described in this region for the first time. Although in the northern part of the typical tundra subzone they occupy zonal positions, dwarf shrub communities with abundant herbs (Luzula tundricolae–Hylocomietum splendentis Telyatnikov et al. 2019) were not found in the studied locations. Tussock tundra (Sphagno–Eriophoretum vaginati typicum) occupies flat or gently sloping hills, and we consider it as the predominant zonal vegetation. The position of the boundary between the southern and the typical tundra subzones is corrected. According to our observations, it lies further north (up to 100 km on the eastern part of the peninsula) than it was shown on previous zoning schemes. Comparison of the syntaxonomic diversity in the southern and northern parts of the typical tundra showed little similarity, only two associations are common (Hierochloo alpinae–Hylocomietum splendentis Telyatnikov et al. 2019 and Tripleurospermo hookerii–Poetum alpigenae Czerosov, Sleptsova et Mironova 2005). We explain this by differences in local lithology: loams were predominant in the northern part and sands dominated in the southern part.

The identity of the highland vegetation of the eastern part of the ridge East Sayan is due to the history of the formation of flora and vegetation in the late Pleistocene, as well as to the features of underlying rocks, mainly represented by limestones. As a result, endemic plant species and communities formed on these ancient alignment surfaces. One of these species is Festuca komarovii Krivot. (Komarov fescue). The relictness of Festuca komarovii is confirmed by the systematic position of the species in the generic complex; it belongs to the distinctive section Leocopoa (Griseb.) Krivot. The section combines only three species – Festuca sibirica, F. hubsugulica, F. komarovii, of which the last two are endemic of the Hangai-Sayan center. The Komarov fescue in the modern vegetation of the East Sayan shows itself as a coenogen and indicator of paleocryogenic landscapes. The research results showed a high coenotic role of this fescue in the vegetation of the studied territory, in particular the syntaxa of the cryophyte-steppe florocenotype (unions Kobresion myosuroidis Mirkin et al. 1983 em. Hilbig 2000 and Potentillo niveae–Caricion pediformisТеlyatnikov 2011). We also described the new association Ptilagrosto mongholicae–Festucetum komarovii Namzalov ass. hoc loco, floristically and coenotically related to the associations of the union Dryadion oxyodontae Zhitlukhina et Onishchenko ex Chytrý et al. 1993, which belongs to the class Carici rupestris–Kobresietea bellardii Ohba 1974. However, one important feature should be noted that the Komarov fescue in communities of associations of tundra and subalpine forest vegetation is noted in a small abundance as an accompanying species. To some extent, this confirms the initial coenogenetic proximity of Festuca komarovii to grass ecosystems – cryophytic stepoids of the periglacial Pleistocene complex.