Peculiarities of Primary Soil Formation in the Conditions of the Southern Tundra of the European North-East of Russia

The paper deals with the influence of hydromorphism (excessive soil moisture content) and soil texture (loams, sands, gravel-sand deposits) on the processes of initial pedogenesis in the conditions of south shrub tundra of the European North-East of Russia. The authors analyzed the morphological structure of soil profiles, and the principal physical-chemical properties of mature and young soils. In 4(5)-6 decades of self-regenerative succession on the territory of quarries for extraction of common minerals, the soil formation and vegetation cover development processes are interrelated and determined by the properties of soil-forming rocks. The drained soils of quarries are found for: isolation of organic horizons (soil litter), soil density decrease in the upper mineral part of profile, tendency to redistribution of silt fraction along soil profile, Fe and Al compounds in the profile. Loams have poor signs of surface gleying, gravel-sand soils - clay formation and accumulation of Al and Fe compounds in the layer under soil litter, sands - podzol formation. Excessively moisture soils are characterized by the development of peat formation processes, humus migration and gley formation. The processes of initial pedogenesis in bioclimatic conditions of tundra are slowed down. This is evidenced by: (1) weak manifestation of zonal signs of soil formation in profiles of young soils; (2) low organic carbon accumulation rate in soil profile. On sands and gravel-sand deposits, the carbon accumulation rate within the 0-20 cm soil layer in automorphic conditions is less than 0.1 t/(ha yr), in semihydromorphic conditions - 0.25-0.30 t/(ha yr), in hydromorphic conditions - 0.42 t/(ha yr). On loams, this parameter attains 0.28, 0.31 and 0.61 t/(ha yr), respectively.