The study and conservation of biodiversity is one of the global problems of modern biology, since currently in many regions of the planet there is a decrease in the species composition of various organisms, including fungi. The obtained data make a significant contribution to the knowledge of the diversity of macromycetes of oak forests in the middle reaches of the Ural River, information about which is still insufficient and fragmented on the territory of Kazakhstan.The article presents data on the biodiversity of mycobiota of the oak forests of the Ural River valley, growing not only in the floodplain of the river, but also in beams, that is, the ravine forests flowing into the central floodplain. We have registered 31 species belonging to 23 genera, 17 families and five orders. The leading families are Polyporaceae, Boletaceae, Russulaceae, Amanitaceae. As a result of our research, it has been found that the mycological composition in ravine oak forests is richer than in floodplain oak forests. The richness of the species composition of macromycetes appears to have been influenced by well-defined associations in ravine oak forests (22 associations), represented by forest boreal tree-shrub species absent in floodplain oak forests, as well as favorable microclimatic conditions, relief, soil cover and various ecotopes that are not observed in floodplain oak forests (16 associations).Ecological-trophic analysis showed the predominance of mycorrhizal (45.1%) and xylotrophs (41.9%) over humus saprotrophs (12.9%). The considered taxonomic composition of macromycetes of the studied area is collected, identified and presented for the first time for this region.

Research works devoted to the identification of species composition of the mycobiota of the Ural River valley within the West Kazakhstan region (WKR) were carried out in the forest communities of the region from 2019 to 2021. On the basis of field studies, a mycological description of black poplar (Populus nigra) forests, which are the main forest-forming species of the studied territory, was carried out for the first time. Also, there was carried out a geobotanical description of the main black poplar communities. The study area is located within two botanical and geographical regions such as in the Eurasian steppe and Saharo - Gobi desert zones, the Holarctic kingdom, on the border of the Boreal and Ancient Mediterranean subkingdoms. Throughout the floodplain along the Ural River poplar forests are the dominant species. When studying the diversity of macromycetes in the biota of cap fungi of black poplar forests, there were registered 42 species of macromycetes belonging to 32 genera and 19 families, 7 orders of the class Agaricomycetes. Ecological-trophic analysis showed a predominance of xylotrophs (18 species, 42,9 %) and humus saprotrophs (13 species, 31 %) over mycorrhizal (11 species, 26,1 %).) According to the results of the study, it can be assumed that the species composition of macromycetes is significantly influenced by the geographical position of the region, the geomorphological structure of the Ural River, as well as the soil-climatic and hydrological conditions of the region. The taxonomic composition of macromycetes collected and identified in the study area is presented for the first time for this area.