Carbon Budget in the Ecosystems of Virgin Spruce Forests in the Middle Taiga

The main components of the carbon cycle in the ecosystem of spruce forests of the middle taiga are characterized. The objects of the study are spruce forests: grasses-blueberry and blueberry-sphagnum. The input and expenditure items of the carbon budget of phytocenoses are estimated by biological productivity. The phytomass and growth of aboveground organs of woody plants were determined by the method of model trees. The mass of the roots is determined by the method of large and small monoliths. The litterfall was revealed with the help of fall catchers. The mass of herbaceous plants, shrubs, and mosses was determined by the method of mowing on 10 sites measuring 0.5 × 0.5 m. The leaf litter of plants of the grass-shrub layer is estimated by their growth. The reserves of organic carbon in soils were determined by the content of humus in various horizons, taking into account the density of the soil. CO 2 emissions were measured using the dark chamber method using an LI-COR 8100 ICG (LI-COR Biosciences, United States). The total carbon pool in the ecosystems of old-age spruce forests is 184.4–187.7 t ha –1 , of which 48–49% are in plants of phytocenosis, and 6–8% are in coarse woody debris (dead wood). In the soil, including the litter and mineral layer, 44–45% of the total carbon pool is stored, about a third of which is concentrated in an organogenic horizon with a capacity of 7.7 cm in a mixed-herb-bilberry spruce forest and 13.1 cm in a blueberry-sphagnum spruce forest. It was found that, in old-age spruce forests, phytocenosis has a significant effect on the dynamics of the content of soluble carbon of organic matter in atmospheric precipitation and in soil waters. The annual carbon deposition by phytocenoses of spruce forests is 3.30 in mixed-herb-bilberry and 3.08 t ha –1 in blueberry-sphagnum. The forest stand plays an extremely important role in carbon production. The carbon of the litterfall has been found to be 2.48–2.84 t ha –1 year –1 . Mineralization losses due to the decomposition of plant residues in spruce forests amounted to less than 30%. The emission of carbon dioxide from the soil surface is affected by the weather conditions of the season. A positive correlation of CO 2 emissions with soil temperature ( r = 0.6–0.8) was noted. The CO 2 emission from the soil of spruce forests was 2.47 t ha –1 season –1 . The carbon budget of the virgin spruce forests of the middle taiga is 0.36 and 0.87 t ha –1 year –1 .