ИСТИНА

The role of fungi in the nitrogen (N) cycle increases in the ecosystems of secondary succession in south taiga. Predominance of fungal biomass under bacterial and participation of fungi in ammonification, nitrification and denitrification elevated from soddy-podzolic soils of abandoned field and mowed meadow to mixed and climax spruce forest. It leads for higher N level storage and retention in the ecosystems and makes N cycle more closed in last stages of succession. The role of bacteria is higher in the soils of initial stage of succession, which intensifies the nitrogen cycle, because higher specific metabolic activity of the bacteria, than fungal activity, especially in the oxidation and reduction of nitrogen compounds. It causes of high losses of nitrogen in the form of nitrate, nitrous oxide and molecular nitrogen from soils of the field and recently abandoned agricultural lands. This conclusion is in the accordance with general principle of the strategy of change of communities, if bacteria and fungi to consider in the context of the r-K continuum and succession from unstable young ecosystems to the climax ecosystems.