In the scientific work, at the first stage of the study, sketches of tables of the growth course of modal fir plantations were developed for the mixed herbs and green moss forest type of the Kansk forestry and the mixed herbs and fern-mossy groups of the Biryusinsky district forestry of the Yemelyanovsky forestry. The ripeness ages were determined according to the data obtained on the dynamics of taxation indicators of fir trees of the corresponding forest type and territorial affiliation. The age of natural ripeness of the studied groups in both regions of the study did not reach its culmination for the studied period. The age of quantitative ripeness for the mixed herbs group of modal fir trees of the Kansk forestry was 60 years, for the green moss – 65 years. In the Biryusinsky district forestry of the Yemelyanovsky forestry, the age of quantitative ripeness for the mixed herbs fir trees was 75 years, and 80 years for fern-mossy ones. The age of technical ripeness for the mixed herbs group of modal fir trees of the Kansk forestry is 70 years, and 65 years for the green moss type of forest. In the conditions of the Biryusinsky district forestry, the age of technical ripeness is in the same age period of typological groups as the age of quantitative ripeness. At the second stage, using the conversion method, the age phytomass of modal fir plantations of various typological-territorial groups was determined and divided into fractions, and the carbon stock was calculated. Within the framework of the study, fir plantations of the fern-mossy type of forest of the Biryusinsky district forestry of the Yemelyanovsky forestry are characterized by a high level of accumulation of phytomass and carbon stock. The total phytomass of the fir plantations by the age of 150 was 205,7 t·m^-3, and the carbon stock was 102,8 t/ha.

Obviously, the forest management system should take into account both the area of study of fir plantations (in this case, the forest-steppe or subtaiga zone) and the typological structure of the territory. On this basis, it is recommended to conduct intensive forestry with a shorter forest management in disturbed, anthropogenic forests (forest-steppe zone, mixed herbs group of forest types). In the foothill part of the Eastern Sayan (subtaiga zone, green moss group of forest types), it is recommended to increase environmental protection activities while preserving biodiversity.

Keywords: Fir, Age, Ripeness, Carbon, Forest management