The Mycelial Component of Eutrophic Peat Soils in the Zone of Active Organic Detritus Decomposition

The analysis of structural indicators (abundance, diversity) of fungal and actinomycete complexes of eutrophic peat soils in the zone of active organic detritus decomposition, represented by litter (layers L and F) and eutrophic peat horizon (TE) was carried out. Samples were taken in swamp forests (black alder forest, pine forest, birch forest, mixed forest) of Tver and Tomsk regions (Russia) in the summer period of 2021.The abundance of mycelial organisms was analyzed by fluorescent-microscopic and plate methods. Species identification of culturable representatives was conducted basing on their phenotypic features. In the litter, the length of fungal mycelium (by 2‒10 times), the number of culturable fungi (by 2‒3 orders), and actinomycetes (by 1‒2 orders) were higher than in the eutrophic peat horizon. The litter enzymatic layer (F) was characterized by the maximum carbon content of the mycelial component (3‒10 mgC/g). The stocks of actinomycete biomass in the zone of active organic detritus decomposition varied from 23 to 60 kg/ha, fungal biomass from 1593 to 3718 kg/ha. The share of litter in the profile stock of mycelial biomass was greater in deciduous forests. Culturable fungi by 70 species of 43 genera and actinomycetes by 42 species from 12 series and 4 sections were isolated from the zone of active organic detritus decomposition. Representatives of genera Penicillium, T-alaromyces, and Trichoderma dominated in the fungal complex, and Streptomyces dominated in the actinomycete complex. The litter was not inferior to the eutrophic-peat horizon in terms of species diversity of fungi and actinomycetes. The species similarity of fungi complexes of the litter and TE horizon was 0.68, and that of actinomycetes was 0.27.