Transformation of the Carbon Budget in Middle-Taiga Spruce Forests on Swamp-Podzolic Soils during Winter Clear Fellings

The paper presents the characteristics of the main components of the carbon cycle in the ecosystems of mature spruce forests (blueberry moist, polytrichum-sphagnum) and in fellings of these spruce forests on peaty podzolic gley soils. Income and expenditure items of the carbon budget of phytocenoses are assessed according to the indicators of production and destruction processes of organic matter. It has been established that the total carbon pool in the ecosystems of mature spruce forests is 160–194 t ha–1, of which in plants of phytocenoses is 44.4–57.8%, in large wood residues (deadwood) is 2.1–9.7%, and in the soil including litter and mineral layer is 35.8–45.9%. In the ecosystems of fellings, the carbon reserves of organic matter are equal to 106–113 t ha–1, of which in soil is 62.5–72.5%, in phytocenoses of plants is 18.0–25.2%, and in large wood residues is 9.5–12.3%. The annual carbon sequestration by phytocenoses of mature spruce forests is 2.4–3.5 t ha–1; in felled areas, it is 1.8–2.2 t ha–1. In the accumulation of carbon in spruce forests, the leading role belongs to the tree stand, and in the fellings, it belongs to ground cover plants. The amount of carbon entering with the litter is 2.0–2.1 t ha–1 in spruce forests and 1.4–1.6 t ha–1 in fellings. The carbon released during the decomposition of the litterfall plant residues in the fellings is 0.54–0.63 t ha–1, which is 37.2–37.6% of the annual decomposition of the litterfall plant residues. It is shown that mature spruce forests are a place of sink and fellings are a source of carbon.