Soils and the Soil Cover of Mountainous Tundra Landscapes on Calcareous Rocks in the Polar Urals: Diversity, Taxonomy, and Nitrogen and Carbon Patterns

Abstract

Landscapes of the northern part of the Bolshoi Paipudynskii Ridge (the Polar Urals) served as a key site to study the taxonomic diversity of soils on calcareous rocks as related to both bioclimatic and geogenic (relief, thickness of eluvial and colluvial derivatives of calcareous rocks) factors. Soils of the postlithogenic trunk of the new Russian soil classification system are developed under different plant communities. They are classified within several soil orders: cryometamorphic soils (Mollic Calcaric Stagnosols), lithozems (Folic Mollic Calcaric Leptosols), organo-accumulative soils (Molic Leptic Calcaric Stagnosols), and gley soils (Folic Calcaric Gleysols). These soils compose either small individual areas, or occur in soil associations. The mass of carbon and nitrogen in the aboveground phytomass ranges within 40–49 and 0.9–2.3%, respectively. The storage of aboveground phytomass (fresh weight) varies from 20 to 1600 g/m2. In each soil profile, the surface horizons have a maximum content of organic carbon and nitrogen (up to 40 and 2.5%, respectively). The Corg and Norg patterns in soils depend on the productivity of plant communities, the composition of falloff, and the conditions for its decomposition. In all soil profiles, the inorganic carbon content (Cinorg) increases down the soil profile reaching 12%. The mineral nitrogen content does not exceed 1%. The contents of N- $${\text{NH}}_{4}^{ + }$$ and N- $${\text{NO}}_{3}^{ - }$$ have their maximums reaching 140 and 30 mg/kg, respectively, in the surface soil horizons.