Cryosols from Tundra and Taiga Zones of Yakutia: Properties, Clay Mineralogy, and Problems of Classification

R V Desyatkin,M V Okoneshnikova,S N Lessovaia,A Z Ivanova

doi:10.1134/s1064229321120048

Abstract

—Data on major properties and clay mineralogy in the profiles of slightly differentiated Cryosols forming in cold ultracontinental climate of Yakutia are discussed. The particular objects are represented by the cryozems of tundra, forest-tundra, and northern taiga of the Anabar and Alazeya plateaus and by the palevaya (pale) soil of middle taiga in Central Yakutia. The differentiation of clay minerals in the vertical soil profiles is poorly pronounced because of the strong homogenizing impact of cryoturbation processes. The profile of pale soil displays minor differences in clay mineralogy despite the strong difference in acid–base conditions of the upper and lower horizons. However, the obtained data suggest that mineral weathering in pale soils of Central Yakutia is more advanced than it was concluded in the 1970s on the basis of data on the absence of pronounced trends in the vertical distribution of clay minerals in their profiles. This is in good agreement with the presence of a sufficiently thick upper humus horizon in these soils, which is typical of the soils of more humid regions. It is suggested that pale soils of Central Yakutia should be classified as soddy pale soils.

Highlights

Soil formation and weathering in the vast permafrost zone of northeastern Siberia and, the Sakha (Yakutia) Republic proceed under conditions close to extreme
We argue that weathering and mineral transformation in pale soils of Central Yakutia are more pronounced than it was considered before
In the profile of permafrost-affected palevaya soil of Central Yakutia, partial dissolution of chlorite is observed in the upper horizons with an acid and neutral reaction, while the proportion of smectitic structures that are more unstable in an acid medium does not change along the profile

Summary

Introduction

Soil formation and weathering in the vast permafrost zone of northeastern Siberia and, the Sakha (Yakutia) Republic proceed under conditions close to extreme. This is one of the coldest places in Eurasia with an ultracontinental climate characterized by a very long period (6.5–9 months) with subzero temperatures and sharp annual temperature fluctuations reaching 70–100°C. Evaporation in forest ecosystems is higher than that in tundra ecosystems [34], and permafrost is a significant source of moisture to ensure forest growth [1, 9, 43]. The cold, ultracontinental climate of Yakutia differs from the climatic conditions of cold, but more humid regions, where soils with permafrost are widespread [6, 36]

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