SEASONAL DYNAMICS OF POPULATION AND BIOMASS OF MICROORGANISMS IN THE SOIL-PROFILE

Seasonal dynamics of population and biomass of microorganisms (bacteri a, mycelium of actinomyces, mycelium and spores of fungi) in the soils of mature spruce ecosystems is studied by the method of luminescent m icroscopy. Seasonal variations in number and biomass of microorganisms are registered throughout the whole profile of the studied soils and reach a maximum in the litter. It is found that the biomass of soil mi croorganisms makes up for 12-65 t/ha, and 65 to 90% of this biomass is confined to the mineral horizons, depending on the season, soil type, and the thickness of the soil profile. Microbial biomass in litter va ries from several hundred kilograms (in spring) to several tens of ton s per hectare (summer, autumn). Mycelium of fungi predominates in the total microbial biomass, and its content increases 3 to 4 times from s pring to summer and 2 to 6 times from summer to autumn.