Within the framework of this study, the forest conditions in the Central Aimag of Mongolia, located in the southern part of the Baikal catchment area, near the southern border of the forest-steppe subzone, were examined. The field materials collected in the summer 2017 - 2018 at the Zuunmod Model polygon serve as the core of the study. An ecosystem map of the Model polygon with the scale 1:50 000 and the Key plot with the scale 1:5 000 was drawn up using World Viеw-2 satellite imagery data (2016). The proved method of botanical indication of forest’ growth conditions is as follows: identification of ecologic and coenotic groups of plant species, calculation of the moisture coefficient based on the ratio of the number of species included in the groups characterizing the extreme conditions of the moisture gradient and distribution of communities in accordance with the values of the gradient in the ecological series. Communities of stages of ecological series serve as indirect indicators of forest conditions: Stage 1: Кu <1, insufficient humifying for tree growth, Stage 2: Кu 1–2, average humifying, Stage 3: Кu >2, sufficient humifying for tree growth. The stages also correspond to the landscape conditions and the character of the vegetation cover.