ИСТИНА

The level of carbon accumulation in soils is controlled by both natural and anthropogenic factors. Therefore, organic matter pools could significantly differ in various soils within the same region. When lacking empirical data on soil organic carbon (SOC) pools, the accuracy of their regional assessments is limited by the scale of soil maps available and the degree their legend units are enforced by relevant factual information. Regional assessments based on small and medium scale maps usually take into account only data on SOC pools for dominant soils varieties. In the taiga zone, besides automorphic soils, significant areas are occupied by semi-hydromophic and hydromorphic soils. The SOC pool in a 1-meter layer of poorly drained soils could be many times higher in then that in automorphic ones. The SOC pools tend to increase in soils with higher degree of hydromorphism. Thus uncertainty of regional assessments derives from the lack of empiric data on semi-hydromorphic and hydromorphic soils and high variability of their SOC pools. The assessments based only on dominating by the area automorphic soils tend to underestimate the SOC pools. The larger share of semi-hydromorphic and hydromorphic soils, the greater would be the degree of the underestimation.