Net primary productivity (NPP) of Soviet forest biomes has been estimated from an equilibrium analysis at seven percent of the global terrestrial NPP, 20 percent of the world's total forest NPP, and half of boreal and temperate forest NPP. However, an equilibrium analysis does not allow the assessment of the role of forest biomes in carbon sequestration because it is based on the assumption that the annual carbon increment in forest biomes equals the amount of carbon released to the atmosphere through respiration. A non-equilibrium analysis accounts for carbon sequestration during specific stages of forest ecosystem development. Sources and sinks of carbon and the sequestration potential of forest biomes in the former Soviet Union are assessed in the present study under non-equilibrium conditions by considering (1) net ecosystem productivity of different age forest stands and their actual coverage, (2) carbon flux related to forest fires, (3) the rate of peat accumulation, and (4) anthropogenic influences.