Estimate of the Soil Carbon Stock of Forested Regions in Russia Using Databases of Soil Properties

Study relevance and goals. Soil is one of the key pools of carbon in terrestrial ecosystems. According to recent data, the soil carbon pool of forest ecosystems may be significantly underestimated. Therefore, obtaining data on the forest soil carbon with reliable interpolation on geographic area contours is of particular interest. In the present work, the available data on soil carbon stocks are aggregated in accordance with forested regions: officially approved ecological administrative spatial units. Forested regions serve as a topological basis for the extrapolation of sample set data to the entire territory of the corresponding region and forest lands in general. The immediate goal of this work is to interpolate data from soil profiles by layers of the soil stratum in forest regions. Study objects and methods. The basis for calculating the carbon stocks in the forest and tundra soils of Russia is a database that combines information on soil sections gathered from a total of 300 literary sources. To determine the spatial differentiation of the mean values, all the sections present in the database are assigned to different forested regions according to their coordinates. For each section, we determine a forested region and a habitat on the basis of the description of the section. A total of 1405 soil sections are selected containing all the data necessary for the analysis: coordinates, calculated data on the carbon content at various soil levels, and data on the habitat in which the section is made. Study results. The regression analysis of the correlation between soil carbon stocks and habitats and soil carbon stocks and the forested regions confirm the selected cartographic basis for the interpolation to be a good fit, which confirms the validity of the choice of the topological basis for soil data interpolation. The total and mean reserves of soil carbon are obtained for an area of 1368 × 10⁶ ha of forest regions in Russia. Conclusions. The total C_soil stock for the territory of Russia within the layers of 0–30, 0–50, and 0–100 cm is estimated at 128.4 × 10⁹ t C, 166.5 × 10⁹, and 215.8 × 10⁹ t C. For the layer of 0–100 cm, the mean reserves are 162 ± 23 t C ha^–1, represented by mean values ± SE (standard error). Maps of the distribution of carbon stocks for the forested regions of Russia are obtained in relation to different depths of the sections.