Production of organic matter and carbon stock in ground vegetation of spruce and birch phytocenoses in the Foothills of the Subpolar Urals

The reserves of phytomass and carbon in the ground cover of spruce and birch phytocenoses in the foothills of the Subpolar Urals in Komi Republic are determined. The concentration and carbon stocks of these forests are currently poorly understood. Three types of forest were studied: bilberry green moss spruce forest, sphagnum spruce forest, polytric birch forest. These forests consist of spruce, birch and fir, stands of different ages and low productivity. It is established that the concentration of carbon in plant species varies from 39 to 50% of absolutely dry matter. High concentration of carbon in bilberry shrubs, low in horsetail, medium in herbs. Carbon content in plants of one species or group of species growing in different forests was similar. Ground vegetation plants accumulate 512-960 g/m(2) organic matter, including carbon 250-409 g/m(2). Carbon accumulation in ground vegetation plants of the sphagnum spruce forest was the highest. More than 50% of the phytomass carbon concentrated in aboveground part of plants. The aboveground parts of shrubs accumulated carbon 8-49 g/m(2), herbs -54-68 g/m(2), mosses -62-140 g/m(2). Aboveground phytomass contents 44-62%, underground phytomass -31-36% of the total carbon reserve in annual production, 86-95% of it returns to the litter. The leading role in the accumulation of carbon in the growth of ground cover belongs to grasses. Annual carbon stock in ground vegetation of spruce forests is 11-20 gC/m(2), in birch forest -9 gC/m(2). Thus, a significant part of the carbon accumulated in annual production of plant cover is included in the destructive process of the carbon cycle.