Taxonomic Analysis of Flora on the Sands of the Don River Valley and Clarification of the List of Rare Species

The taxonomic structure of the flora of the Archedinsko-Donskoi sandy massif is analyzed and rare species are identified. The novelty of this research lies in obtaining new data for adjusting schemes of botanical–geographical zoning of steppe territories in the southern part of Russia as a whole and the distribution area of sandy massifs in particular. The formation of the floristic list was based on data obtained during field surveys conducted between 2016 and 2024, as well as from the flora list available in the Global Biodiversity Information System (GBIF) of the INaturalist platform, which contains information on plant findings for the period from 1990 to 2024. It has been established that the current floristic list of the sandy massif comprises 677 species from 324 genera and 95 families, belonging to eight classes and seven divisions. The division Magnoliophyta is the most represented, accounting for 79% of the flora of the territory. The overall generic coefficient is 2.09. The highest generic coefficients are observed in the families Amaryllidaceae (11.0), Plantaginaceae (8.25), Cyperaceae (6.8), Juncaceae (6.0), Salicaceae (5.0), and Violaceae (5.0). The leading position in the flora is held by the family Asteraceae, represented by 103 species (15.2%), and the family Poaceae, which includes 68 species (10.0%). A large number of taxa are also characteristic of the families Cyperaceae (34), Plantaginaceae (33), Caryophyllaceae (32), Fabaceae (31), Lamiaceae (29), Brassicaceae (22), Rosaceae (20), and Amaranthaceae (17). The sandy landscapes of the Archedinsko-Donskoi massif with elements of boreal flora, confined to reservoirs, floodplain areas, and areas with an atypical water regime, are a unique object for the conservation and maintenance of the biological diversity of steppe territories. Here 30 species listed in the Red Book of Volgograd Oblast (2017) and 12 species listed in the Red Book of the Russian Federation (2008) were identified. They are under threat of extinction: Aldrovanda vesiculosa L., Lycopodiella inundata (L.) Holub., Lycopodium clavatum L., Climacium dendroides (Hedw.) Web. et Mohr., and Clematis orientalis L. The largest list of Red Book representatives is represented by the families Asteraceae (three types) and Orchidaceae (four types). The research results can be useful in studying the ecology of plant communities and the species in them, for the restoration and preservation of lost biological diversity of the vegetation cover of sandy ecosystems.