The ratio of boreal and steppe floristic elements in phytocoenoses involving Populus alba, P nigra, P. tremula and P. × canescens in the Zhaiyk river floodplain

Abstract

The article presents the results of a comprehensive ecological, phytocoenotic, and floristic study of forest communities involving representatives of the genus Populus L. in the Ural River valley within Western Kazakhstan. The research was conducted in 2024-2026 across steppe, semi-desert, and desert zones. Based on 26 geobotanical releves, a syntaxonomic analysis of floodplain and ravine forests was carried out, encompassing various elements of floodplain relief and moisture gradients. Four populations of the genus Populus were identified and characterized, represented by the species Populus alba L., Populus nigra L., Populus canescens (Aiton) Sm., and Populus tremula L. The studied phytocoenoses are characterized by pronounced vertical stratification, high floristic diversity, and a mosaic vegetation structure determined by differences in soil and hydrological conditions. The total number of vascular plant species within the communities ranges from 16-55. Species of the family Salicaceae plays a leading role in forming the coenotic core, while the herb layer is mainly represented by members of Poaceae, Asteraceae, and Fabaceae. Chorological analysis revealed the predominance of boreal forest and Eurasian floristic elements, with a significant contribution of steppe and Pontic species, reflecting the ecotonal nature of the region’s floodplain forests. An expansion of the ecological-coenotic amplitude of certain species was observed under changing hydrological conditions, particularly within the desert zone.The obtained data supplement existing knowledge on the structure, floristic composition, and geographical distribution of poplar forests in Western Kazakhstan and are important for the monitoring and conservation of floodplain ecosystems.

Key words: Populus, floodplain forests, phytocoenoses, floristic structure, boreal and steppe elements, Zhaiyk river.