The Effect of Hydromorphism on Soils and Soil Organic Matter during the Primary Succession Processes of Forest Vegetation on Ancient Alluvial Sands of the European North-East of Russia

The article considers the role of hydromorphism in the soil formation processes on ancient alluvial sandy deposits at the primary succession period. Soil organic matter was given special attention. The studies were carried out in the European north-east of Russia (the Komi Republic) in the middle taiga subzone in the territory of a building-sand quarry (61°57′35″ N, 50°36′22″ E) and background sites near the quarry. The authors analyzed the morphological structure of soil profiles, and the principal physical-chemical properties of mature and young soils forming under pine forests. Formation of forest litter and humus-accumulative horizons, as well as soil organic matter accumulation were thoroughly studied. Already in the fourth–fifth succession decades, the soils in a series of increasing hydromorphism actively demonstrated regularities that are normally characteristic of background soils, for example, increase in acidity, silt fraction, carbon and nitrogen reserves. Against moisture deficiency, the accumulation rate of organic carbon became slow and amounted to 0.07–0.11 t ha−1 year−1. The excessive soil moisture content increased the rate up to 0.38–0.58 t ha−1 year−1 due to the conservation of plant material in the form of peat. The upper 50-cm profile layer of young soil contains Corg stock 3–5 times less than that of background soils. The major soil-forming processes are litter formation and podzolization in drained conditions, litter formation in conditions of high moisture, and peat formation and gleization against excessive moisture

Zonal Patterns of Changes in the Taxonomic Composition of Culturable Microfungi Isolated from Permafrost Peatlands of the European Northeast

This paper provides the results of a study on fungal species diversity in the active and permafrost layers of peatlands within frozen peatbogs in the flatland areas of the cryolitozone, European Northeast of Russia (forest-tundra zone, southern and northern tundra subzones). Fungal taxonomic list includes eighty-three species from seventeen genera and two forms of Mycelia sterilia. The phylum Mucoromycota is represented by fifteen species (18% of total isolate number), and these species exhibit the following distribution by genus: Mucor (four), Mortierella (seven), Umbelopsis (three), Podila (one). Ascomycota is represented by sixty-eight species from thirteen genera. The genus Penicillium dominates the species saturation (thirty-seven species, 44%). Soil microfungal complex is represented by rare species (51%), random species (32%), frequent species (15%), and dominant species (2%). In peat soils, dominant species are Penicillium canescens (72%) and non-pigmented (albino) Mycelia sterilia (61%); abundant species are Talaromyces funiculosus (41%), Pseudogymnoascus pannorum (36%), albino Mycelia sterilia (29%), Umbelopsis vinacea (25%), Mortierella alpina (17%), Penicillium decumbens (21%), P. spinulosum (20%), and P. canescens (17%). In active layers of peat soils, abundant species are Penicillium thomii (14%), Mycelia sterilia (13%), Penicillium spinulosum (13%), Penicillium simplicissimum (13%) in forest-tundra; Talaromyces funiculosus (21%), albino Mycelia sterilia (15%), Umbelopsis vinacea (14%) in southern tundra; Penicillium decumbens (23%), P. canescens (17%), P. thomii (13%) in northern tundra. In permafrost peat layers, abundant species are Penicillium spinulosum (17%), Talaromyces funiculosus (34%), and Umbelopsis vinacea (15%) in forest-tundra; Pseudogymnoascus pannorum (30%) and Mortierella alpina (28%) in southern tundra; Pseudogymnoascus pannorum (80%) in northern tundra