Vol 74, No 4 (2019)

A comparative description of the structural and functional organization of plant debris and forest litter during natural postagrogenic reforestation in the 12-, 40-, and 100-year-long chronoseries of ecosystems is given. With the increase in the age of forests, the total reserves and diversity of litters rise; and the portion of easily decomposed components and their pH and ash content become smaller. The grass ground cover is replaced by grass–dwarf-shrub cover, which indicates a decrease in the trophicity of ecosystems. The properties of forest litter are adequately reflected in the ground cover composition. Forest restoration is accompanied by a regular decrease in the decomposition intensity of the ground detritus and in the rate of the biological cycle. The spatial differentiation of litters plays a role of a trigger for the subsequent divergence of soil organic profiles.

Mineralization resistance of water-soluble organic matter (WSOM) extracted from litter of podzol becomes higher upon the interaction with mineral horizons. Both the portion of WSOM susceptible to mineralization and its mean decomposition rate decrease two and three times, respectively, after its migration through the E eluvial horizon. Sorption in the BF horizon enhances the stability of the input organic matter. The relative content of mineralized carbon decreases to 2% (eight times). In natural soils, adsorbed organic matter may be even more resistant to mineralization due to lower temperatures and biological activity and thus represent the basis for the formation of humus reserve. Taking into account the calculated mineralization rate, the organic carbon accumulation in the BF horizon as a result of WSOM sorption may reach 13.5 mg/100 g per year, but it depends on the concentration of organic substances in soil solutions, hydrological regime, and other factors.

Currently, the taxonomy of peat soils is not given more attention, especially with regard to taxonomic units in the species rank. The diagnostics of 51 soil profiles in the various oligotrophic mire types in the Numto Nature Park (north taiga subzone of West Siberia) has brought about proposals to improve the existing soil classification. It is suggested to: 1) limit the peat horizon thickness in the peat-gleyzem type to 30 cm; 2) divide the peat-gleyzem type by the trophic status into oligotropic and eutrophic subtypes; 3) expand the list of taxa determined by the botanical composition of peat by means of the division of soil species into subspecies on the basis of classifications of peat and peat deposits; 4) use current vegetation as one of the main diagnostic (indicative) criteria in determining the soil type in mires; and 5) use the degree of decomposition of the peat layer underlying the peat soil for determining the variety of peat soil. The article draws attention to the difficulties in determining the classification position of soils of frozen large mounds in palsa bogs and proposes alternative solutions to this problem.

The paper presents a comparative analysis of the structural and functional characteristics of microbial communities of gray forest soil of fallow and intensively cultivated areas. The long-term anthropogenic impact with massive annual mineral fertilization when growing a monoculture of potatoes has led to degradation of the soil microbial system. A catastrophic decrease in the functional potential of the microbial system (environmental services) is shown using eco-exergy as a thermodynamic indicator of soil “health”.