Soil water balance and the transformation of the former plow layer (Ap) under a 50-year-old mown hayfield and a 22-year-old artificially planted spruce stand on the lower part of a gentle slope in the southern taiga subzone (Moscow region) are analyzed. The plots are allocated to the post-agrogenic soddy-podzolic loamy soil; the groundwater depth is 3-4 m. The soil profiles under the meadow and forest vegetation have clear morphological differences. Under the hayfield, humus accumulation in the former Ap horizon is active in the upper 13 cm. Within this layer, a soil microprofile consisting of the litter (3 cm), proper humus (4 cm), and transitional horizons of the light gray color and fine crumb structure has developed. The remaining part of the former Ap horizon preserves its pale brown color and cloddy structure. In some micro-zones, coprolites are accumulated, which attests to the increasing activity of soil mesofauna. Under the spruce stand, a pale brown soil microprofile has developed in the upper part of the former Ap horizon. A thin (0.8 cm) needle litter is underlain by the bleached mineral horizon. The thickness of the newly formed humus horizon is the same as that under the meadow, but it has a more distinct crumb structure. The transitional horizon (10 cm) has a grayish color and is relatively compact. A tendency for the platy structure is seen. The features of eluviation processes manifest themselves in the entire thickness of the former Ap horizon. Data on the water balance show that the soil functioning under the meadow and forest vege-tation has its own temporal dynamics. Three different stages can be distinguished with respect to the character of water supply, water consumption, and lateral water flows. During the first eight years (1981-1989), the total reserves of soil water under both cenoses were approximately similar with a tendency for their increase under the tree stand. The maximum difference in the soil water storage under the tree stand and the meadow reached 60 mm. Under the meadow, the lateral discharge of soil water was by 7% higher than that under the forest stand, whereas the soil water loss through infiltration and evaporation was by 10% lower. From 1990 to 1994, the reserves of water in the snow under the trees became lower, and the depth of soil freezing increased. The lateral discharge of soil water under the meadow was by 25–30% higher than that under the trees, and the soil water loss through infiltration increased under the trees and became 20% higher than that under the meadow. From 1995 to 2003, the soil water reserves under the meadow became 40-50 mm higher than those under the spruce stand. The depth of soil freezing under the trees increased and reached 1 m in some winters. The lateral soil water flow was still 30 to 40% higher under the meadow. The surface runoff, as well as the lateral soil water flow, was higher under the meadow during the whole period; the difference varied from 5 to 35%. The maximum values were registered in the years with cold low-snow winters and in the extremely wet years. The surface runoff in such years reached 70% of the total water supply. The snow depth under the trees decreased by the end of the observation period, and the depth of soil freezing increased in comparison with the meadow. In the soil under the spruce plantation, the development of the tree canopy sharply decreases the heat supply and the snow accumulation on the soil surface, which leads to a decrease in the soil temperature. The absence of thick litter under the young spruce plantation ensures the high thermal diffusivity at the soil surface, which also contributes to a greater depth of freezing. The cold winter conditions facilitate the development of the cryogenic platy structure in the lower part of the former Ap horizon. In the soil under the meadow, the effect of cold winter temperatures on the soil structure is less pronounced. Only the upper part of the former Ap is transformed under the impact of plant roots and humus accumulation. The lower part preserves its cloddy structure. Thus, under the meadow, the rate of surface runoff is higher due to the active snow melting and the absence of infiltration into the frozen soil in the spring. The cloddy structure of the sub-surface horizon also hampers water infiltration. Under the spruce plantation, the soil is colder, the snow reserves and the rate of snow melting in the spring are lower, so that the water infiltration is more pronounced, which leads to the development of eluviation features in the topsoil.