Semenova Tatiana Alexandrovna

A comprehensive study of the mycobiota in eutrophic peat soils under forests was conducted: birch forest, mixed forest (Tomsk District, Tomsk Region), black alder forest, and pine forest (Zapadnodvinsky District, Tver Region). The litter (layers L and F) and eutrophic peat horizon (TE: 0–20, 20–30, and 30–50 cm) were analyzed during the summer and autumn of 2021. The stocks and structure of fungal biomass were studied using luminescent microscopy, and the number of cultivated representatives was determined using the sowing method. Fungi were identified on the basis of phenotypical characteristics and the results of 26S rRNA nucleotide sequence sequencing. It was found that in the litter of the studied soils, fungal biomass ranged from 2 to 30 mg∙g‒1, fungal biomass stocks ranged from 28 to 189 g∙m–2, and fungal biomass carbon stocks ranged from 139 to 945 kgC∙ha‒1. In the eutrophic peat horizon, they ranged from 0,4 to 19,4 mg∙g–1, from 52 to 622 g∙m–2, and from 262 to 3110 kgC∙ha‒1, respectively. All indicators of fungal abundance increased from summer to autumn. The contribution of litter to fungal biomass reserves was more significant in soils under deciduous forests — up to 67%, while in soils under coniferous forests it did not exceed 10%. Fungal biomass in the studied horizons was mainly represented by mycelium, with spores accounting for 1 to 40%.The number of cultivated fungi in the studied soils ranged from 103 to 106 CFUg‒1 and was 2–3 orders of magnitude higher in litter than in TE. Seasonal changes in the number of micromycetes were detected mainly in litter (summer values exceeded autumn values by 1–2 orders of magnitude). Over two seasons, 85 species of micromycetes from 46 genera, 27 families, 15 orders, 7 classes, and 2 divisions (Mucoromycota and Ascomycota) were isolated from the studied soils.Representatives of the Ascomycota division predominated, accounting for 89% of the total species composition. In soil microfungal communities, fungi of the Penicillium and/or Trichoderma genera dominated or were frequently encountered, but the vast majority of representatives of other genera were characterized as rare and incidental. In litter, the Shannon index ranged from 0,78 to 2,32, and in TE from 0,31 to 2,55. In autumn,as rule, a decrease was observed in almost all soil horizons.The species similarity of the communities of cultivated fungi (Ks) of the studied soils varied in the range of 0.42–0.56, and between horizons reaches 0.70.