Abstract
This study investigates the composition, diversity, and ecological adaptation strategies of plant communities in the Irtysh River floodplain (Northeastern Kazakhstan) under natural and anthropogenic pressures. Field-based geobotanical surveys were conducted from May to August 2024 across 40 representative plots. Standard phytocoenotic description methods were employed, along with phenological and ecological assessments. A total of 549 vascular plant species from 74 families were identified. Ten rare and protected species were recorded in the region. Major anthropogenic threats included hydrological regulation, grazing, seasonal burning, and biological invasions. Notably, Acer negundo, Echinocystis lobata, and Cyclachaena xantifolia were dominant among invasive species. Variability in flood patterns (36% inundation in 2023 vs. full coverage in 2024) significantly affected plant productivity and composition. The floodplain demonstrates high biodiversity but is increasingly vulnerable. Maintaining flood regimes, controlling invasive species, and managing grazing practices are essential for ecological resilience. This study provides a foundation for regional conservation planning and sustainable land use policy.