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

Structural indicators (abundance and diversity) of the fungal and actinomycete complexes of eutrophic peat soils in the zone of active organic detritus decomposition, namely, litter (L and F layers) and eutrophic peat horizon (TE), were analyzed. Samples were e taken in swamped forests (black alder, pine, birch, and mixed forest stands) of the Tver and Tomsk oblasts (Russia) in summer of 2021. The abundance of mycelial organisms was measured by fluorescence microscopy and plate method. Species of culturable representatives were identified by their phenotypic traits. The fungal mycelium in the litter is two–tenfold longer as compared with the TE horizons; the abundance of culturable fungi is bigger by two‒three orders of magnitude; and that of actinomycetes, by one‒two orders of magnitude. The litter fermentative layer (F) displays the maximum carbon content of the mycelial component (3‒10 mg C/g). The stocks of actinomycete biomass in the zone of active organic detritus decomposition varies from 23 to 60 kg/ha and of fungal biomass, from 1593 to 3718 kg/ha. The share of litter in the total stock of mycelial biomass across the profile is larger in deciduous forests. In total, 70 species of culturable fungi belonging to 43 genera and 42 actinomycetes species of 12 series and 4 sections were isolated from the zone of active organic detritus decomposition. Representatives of Penicillium,Talaromyces, and Trichoderma genera are prevalent in the fungal complex and of Streptomyces, in the actinomycete complex. The litter does not yield to the TE horizon in terms of species diversity of both fungi and actinomycetes. The species similarity of fungal complexes of the litter and TE horizon is 0.68 and that of actinomycetes, 0.27. [ABSTRACT FROM AUTHOR]