Abstract
<jats:p>The article presents the results of a comprehensive analysis of the floristic and taxonomic diversity of fruit and berry plants in Western Kazakhstan (Mangistau and Atyrau regions). Field studies conducted in 2024-2025 revealed more than 60 species, mainly belonging to the families Rosaceae, Caprifoliaceae, Elaeagnaceae and Grossulariaceae. The dominance of the Rosaceae family was confirmed; the genera Crataegus, Rosa, Lonicera and Ribes form the basis of shrub-tree communities in the region. The use of Shannon, Simpson, Margalef, Pielou and Jaccard indices made it possible to assess both alpha and beta diversity of the flora quantitatively. It was found that the Akmysh and Kogez sites form the most similar floristic group in composition, while Inderbor is distinguished by pronounced isolation and uniqueness of the species composition. The Zheltau mountain range acts as a transit zone uniting the floras of the Mangistau and Atyrau regions. The results obtained indicate a high mosaic of the floristic cover, significant ecological plasticity of fruit and berry plants and, at the same time, the vulnerability of individual endemic and rare taxa. They are of great importance for developing strategies for the protection of biodiversity, preserving the gene pool and the prospective use of economically valuable species in breeding and introduction programs.</jats:p>