Geographical and genetic features of soil formation and diversity of the permafrost soils of Central Yakutia

Abstract

The aim of the study. The aim of this article was to identify the geographical and genetic features of soil formation in the cryolithozone of Central Yakutia and to assess the diversity of all types of permafrost soils of this territory.

Location and time of the study. Soil-geographical and soil-genetic studies were carried out near the Middle Lena, on the territory of Central Yakutia within various geomorphological tiers of the Central Yakut Plain at different times, starting from the 1990s.

Methodology. In carrying out these works, widely used methods of soil research were used, such as comparative geographical, profile genetic and comparative analytical in combination with well-known and commonly used analytical methods. At the same time, all the main results of soil studies conducted on this territory by our predecessor permafrost soil scientists were taken into account in a comparative aspect.

Main results. According to the obtained results, it is necessary to state that this region of the cryolithozone is characterized by extremely peculiar landscape and climatic conditions of soil formation,  the formation of the cryogenic soils occurring in a cryoarid climate, mainly on loose alluvial deposits of various ages, under forest and meadow-steppe vegetation and continuous permafrost. In the studied territory, the cryogenic soil-forming processes are crucial for the development of properties, composition and regimes of these permafrost soils, causing their high diversity and diversity of the soil cover of Central Yakutia. The systematic list of permafrost soils of the studied territory includes 17 types and 21 subtypes of soils and is forecasted to expand as the study of the soil cover of this unique region of the cryolithozone deepens. At the same time, the diversity of soils there is formed by the six types of zonal and azonal forest, five types of meadow-steppe and five intrazonal types of the permafrost soils. A broader concept of "permafrost soils" is proposed, in contrast to that interpreted in the current classification of soils of Russia and WRB, the essence of which is that regardless of the depth of seasonal thawing, all soils underlain by the permafrost are called permafrost soils. In these soils, the interlocking of seasonally and permanently frozen layers is observed in winter. These soils may differ in pronounced cryomorphic features (cryozems, fawn) or not have them (podburs, podzols, chernozems), being characterized by a permafrost type of temperature regime.

Conclusion. In the cryolithozone environment of Central Yakutia, elementary soil-forming processes occur under cryogenesis conditions, which in the general hierarchy of soil-forming factors is considered at the subfactorial level; minor variations of the soil-forming factors can change the directions and rates of the soil-forming processes and, ultimately, lead to a high degree of diversity and contrast in the soil cover of the studied territory.