Abstract <p>Soil and hydrological conditions of a solonetzic complex have been studied at the Dzhanybek Research Station of the Institute of Forest Science of the Russian Academy of Sciences in the semidesert of the Northern Caspian region, an object of 70-year monitoring of natural and anthropogenic transformations. The classic works of Prof. A.A. Rode and research led by Prof. T.A. Sokolova have been used as the standard for comparison. The soils of virgin areas and meadow-chestnut soils (Haplic Kastanozem) of micro- and mesorelief depressions under separated forest stands and massive forest plantations, represented mainly by pedunculate oak and Siberian elm have been studied. The study includes analyzes of the meteorological and climatic data, calculations of the moisture coefficient of the territory; assessment of the groundwater dynamics chemistry and mineralization, composition of soil water extracts, and the supplies of easily soluble salts and chlorine ion have by the half-meter layers of the soils. Three significantly different periods of changes in soil and hydrological conditions are associated with fluctuations of the groundwater table and the changes in moistening of the region. The modern stage, which began in the early 2000s, turned out to be the driest, with a moisture coefficient of 0.24 ± 0.07. Thus, the rise of the groundwater level in the early 1980s had changed by its lowering. The previously observed salinization trend in meadow-chestnut soils (Haplic Kastanozen) of virgin depressions is maintained in the current conditions with the groundwater level of 5.6 ± 0.2 m and average mineralization of 3.41 ± 0.27 g/L due to the accumulation of Cl^–, Ca²⁺, and Na⁺ ions. Groundwater mineralization in the micro- and mesorelief depressions under the separated and massive forest stands increases due to high evapotranspiration of the trees; however, the additional accumulation of snow by forest belts and the periodically-flushing type of water regime with limited desuction contribute to the presence of a root-accessible desalinated zone with a thickness of 350 and 250 cm, respectively. The revealed patterns, covering a 70-year period of observations, allow a more rational approach to the landscape management in such unfavorable climatic conditions.</p>