SOIL ORGANIC CARBON STOCK IN MONGOLIAN FOREST

Studied soil organic carbon stocks of the major forest soils of Mongolia. More than 98.8% of the country's forest area is distributed across Umbrisols (Gelic), Leptic Umbrisols, Gleyic Umbrisols, Mollic Umbrisols, and Podzols (Arenic). For the calculation of soil organic carbon stocks, we used existing soil data together with additional sampling and analysis results for areas where data were lacking. In total, data from 1,071 soil samples and 210 soil profiles were used. Soil analysis data were converted to the standard depth intervals of 0-30, 30-60, 60-100, and 0-100 cm using the weighted average method. The most widespread forest soil in Mongolia is Leptic Umbrisols, and the average SOC stock for 0-30 cm soils is about 66.9 Mg C ha^-1; for 30-60 cm soils, 14.1 Mg C ha^-1; and for 0-100 cm soil, 86.3 Mg C ha^-1, respectively. Gleyic Umbrisols are formed on the lower parts of north-facing taiga forest slopes. The average soil organic carbon stock of Gleyic Umbrisols is high, reaching up to 136.0 Mg C ha^-1 in the 0-100 cm soil layer. The SOC stock for 0-30 cm soils is 86.9 Mg C ha^-1, and for 30-60 cm soils, 38.6 Mg C ha^-1. The average SOC content in Umbrisols (Gelic) is 8.0%, in Leptic Umbrisols 4.1%, in Gleyic Umbrisols 3.8%, in Mollic Umbrisols 5.7%, and in Podzols (Arenic) 0.65%. Podzols (Arenic) are distributed in the lowest parts of the forest, and their topsoil organic litter is comparatively less abundant than in the other soil types. The mean SOC stock of Podzols (Arenic) for 0-30 cm soils is 28.8 Mg C ha^-1, for 30-60 cm soils 18.5 Mg C ha^-1, and for 0-100 cm soil 55.0 Mg C ha^-1, respectively. Up to 52-78.9% of SOC resources in forest soils are accumulated in the upper 30 cm of soil. Further forest soil studies are needed to achieve full coverage of Mongolia's forest area. In particular, the high-mountain taiga regions and remote areas of the Khentei and Khovsgol mountain regions have not been sufficiently studied.