NATURAL AND ANTHROPOGENIC DEGRADATION PROCESSES DESERTED STEPPES OF THE UBSUNUR BASIN
Steppes in Tuva occupy intermountain basins with altitudes of 550-1200 m above sea level, the lower parts of mountain slopes, and high terraces of river valleys. Large massifs of steppes are typical for the Ulugh-Khem and Ubsunur basins. Studies to assess the state of soil and vegetation cover were conducted in the North-Eastern (Tuva) part of the drainless Ubsunur basin in July-August 1997-2020 using the route method. The location of the basin between the boreal landscapes of Siberia and the desert-steppe landscapes of Central Asia is characterized by a variety of landforms, heterogeneity of soil and vegetation cover, and a unique distribution of climatic factors and geological history. The source material was our own data from soil and geobotanical studies and remote materials from different observation periods. Observation data from different survey years were linked to the Landsat satellite image for July-August 1997-2019. Route studies were carried out on the main geomorphological profiles from the southern foothills of the Western and Eastern Tannu-Ola ranges to the coast of oz. Ubsa-Nur (from North to South). Reference soil sections were laid at key sites, morphological descriptions of soil profiles and horizon-based sampling were carried out. Soil samples were taken to determine the humus content, granulometric composition, size and nature of salinity-the main indicators of soil desertification. Observations also covered the Eastern and Western parts of the basin, which revealed the direction of degradation of desolate steppes in different geomorphological positions of the territory, but also with different nature and intensity of anthropogenic impact.