Formation of organic soil horizons during the initial pedogenesis in the taiga zone of the European Russian Northeast

Investigations were carried out in the European Russian Northeast (Komi Republic), -in the middle taiga subzone, in the (construction sand) quarry area. Formation of the soil profile within two decades after forest reclamation practices (Pinus sylvestris planting) was considered. Specifics of litter and humus horizons formation, processes of humus formation and accumulation on substrates of different granulometric composition were determined. It is shown that the rate of these processes is determined by the species composition and structure of the plant community. By the end of the second decade, up to 2.7 t·ha-1 of organic carbon accumulates in the humus-accumulative layer (0-20 cm) of sandy and sandy-loam soils, 6.3 t·ha-1 - in clay-loam soils, and 0.1 and 0.4 t·ha-1of nitrogen, respectively, accumulates there as well. The accumulation rate of Corg in the soil of the sandy and sandy-loam quarry reached 0.16, in the clay-loam quarry - 0.37 t·ha-1·year-1. The organic horizons of the forming soils demonstrate a decrease of the mass fraction of calcium, potassium, phosphorus and an increase in iron and aluminum down the profile.