The stock and structure of organic substances in the pine tree plantations on the overburden dumps of open-cut coal mines in Middle Siberia have been determined. It has been shown that the forming forest biogeocenoses differ from the natural phytocenoses and soils of the forest landscapes in the structure of the carbon pool and its distribution between the vegetation and soil components. In artificial forest ecosystems, the bulk of the plant component is accumulated in the aboveground part of the forest stand (40-59%). The aboveground grass cover contains only 0.1-1.4% of the total phytomass stock of the ecosystem. The annual accumulation of organic substances in the initial soils amounts to 0.28-1.45 t/ha.