Floristic findings from the protected area of the Tsugeer-Els cluster of the Ubsunur Basin Biosphere Reserve (Tyva Republic)

Being centers for environmental protection, as well as research and environmental education, biosphere reserves play an important role in the global biodiversity conservation. The first mandatory stage of the reserve's work is an all-taxa biodiversity inventory. The last list of the vascular plants of the Ubsunur Basin Biosphere Reserve compiled in 2009 includes 1263 species, but it should be noted that the reserve's territory has been insufficiently studied. This is confirmed by the results of special floristic studies of two (Mongun Taiga and Aryskannyg) of nine reserve clusters, which revealed some new species for the reserve's territory and allowed to precise the distribution of plants within individual sites. The aim of this research was a vascular flora inventory of the Tsugeer-Els cluster. Tsugeer-Els sands are located in the northeastern part of the Ubsunur Basin on the left bank of the Tes-Khem River between 49°57'-50°11'N and 95°07'-95°28'E. They are an almost isolated branch of the large Altan-Els sand massif, which is located on the adjacent territory of Mongolia. The protected area of the cluster includes the freshwater Tore-Khol Lake, the sands of Eder-Elezin, rocky outcrops and the left bank of the Tes-Khem River Valley. Fieldwork was carried out in June 2019. The routes covered the sand dunes in the principal part of the cluster, the coastal zones of Tore-Khol Lake, vegetative complexes of moist depressions, rocky outcropes, drying floodplain lakes with halophytic vegetation, areas with anthropogenic disturbance (roads, pastures, lake recreational areas), and the Tes-Khem River floodplain. During the routes, we compiled floristic lists, carried out visual observations of ecotopological and phytocenotic features of the species, noted species abundance, and sampled herbarium specimens in some cases. All herbarium specimens cited in this article were deposited in the P.N. Krylov Herbarium of Tomsk State University (TK). 18 species of vascular plants were added to flora of the Tsugeer-Els cluster of the Ubsunur Basin Reserve. Of these, 4 species are also new for the Erzinsky natural area of Tuva: Alyssum turkestanicum var. desertorum (Stapf) Botsch., Carex vesicaria L., Isatis costata C.A. Mey., Silene borysthenica (Gruner) Walters. Androsace lehmanniana Spreng. is also new for the Ubsunur desert steppe subregion. 13 species were added to the species list of the Tsugeer-Els cluster: Anemone sylvestris L., Angelica tenuifolia (Pall. ex Spreng.) Pimenov, Eleocharis uniglumis (Link) Schult., Equisetum arvense L., Equisetum palustre L., Gentiana riparia Kar. & Kir., Poa argunensis Roshev., Polygala hybrida DC., Potentilla pensylvanica L., Pyrola rotundifolia L., Scorzonera radiata Fisch. ex Ledeb., Thesium repens Ledeb., Trifolium lupinaster L. We also noted that Tephroseris palustris was mistakenly omitted in the reserve flora species list for the Tsugeer-Els cluster. Most of the new species were found in hard-to-reach floodplain habitats in the Tes-Khem River Valley. The finding of Alyssum turkestanicum var. desertorum, Isatis costata, Silene borysthenica in the coastal zone of Tore-Khol Lake, in our opinion, is the result of the increase in the recreational load recently. The paper contains 11 References. The Authors declare no conflict of interest.

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