Abstract
The study presents the results of an investigation into the soil and ecological parameters of the Sarytogan Delta and the assessment of survival and growth of Populus diversifolia seedlings under different moisture conditions. Key indicators were analyzed: distance to the nearest water body, duration of flooding, depth of the capillary fringe and the third degree of soil moisture, soil water content, and electrical conductivity at different horizons. It was shown that the soils of the delta are characterized by a deep occurrence of the capillary fringe (130-170 cm), limited water content (12-18% in the 0-100 cm layer), and moderate salinity, which create stressful conditions for woody vegetation.The survival rate of Populus diversifolia was 96% in the nursery, while in the Sarytogan Delta it decreased to 85% at a distance of less than 300 m from water bodies and to 68 % at greater distances. Morphometric growth parameters (height, stem diameter, and crown diameter) also declined with increasing distance from water sources. Comparison with national and international studies confirms a general pattern: the successful establishment and growth of woody species in delta ecosystems are determined by the combination of hydrological regime and soil salinity. The results emphasize the need for regular monitoring of the water regime and the application of artificial irrigation measures to increase the productivity and resilience of the Sarytogan Delta.