The paper summarizes the results of long-term multidisciplinary studies of forest soils and the soil cover, analyses the diversity of forest soils in the Kivach strict nature reserve. The structure of the soil cover is investigated at the coenosis and parcel levels; distinctive features of soil formation over bedrock, glaciofluvial sandy and clayey deposits are described. Physical and physiochemical properties of soils in coenoses forming ecological series by moisture and nutrient status have been studied, their qualitative and functional features have been determined. Ecological and evolutionary associations between soil properties, woody plants, floristic composition, abundance and species composition of plants in the soil cover have been identified. The concept of stable heterogeneity of soil properties and the soil cover as the basis for conservation of the biodiversity of forest ecosystems is formulated.