«Oruku-shynaa» cluster of «Ubsunurskaya kotlovina» reserve (Ubsunur hollow) (the Republic of Tyva, Russia): soil conditions and vegetation cover

The article presents the results of studying soils and vegetation cover of the Oruku-Shynaa cluster, a natural feature of the Ubsunur Hollow Biosphere Reserve, which is an acquisition of the UNESCO heritage. The Ubsunur Basin, the northernmost of the inland basins of Northwestern Mongolia, is the destination of Inner Asia, where nature preserves an exceptional “parade of landscapes” of unusual diversity, which predetermines the creation of biosphere reserves in Russia and Mongolia by a cluster approach. Nine clusters have been created on the territory of the Republic of Tuva (Russia). One of them is Oruku-Shynaa. The purpose of creating the Oruku-Shynaa cluster is to study natural complexes and objects, preserve biodiversity, and carry out long-term environmental monitoring of the reference territories of the Ubsunur basin. The complete descriptions of soil sections were made on six sample sites and fifty geobotanical homogeneous sites in different years. The background soils are brown desert-steppe soils, which have local hydromorphic manifestations of meadow, saline, and solonetsous soils. The study of the temperature of soils in the middle of summer showed that the most mobile dynamics of soil temperature is observed at a depth of 5 cm from the surface. The reaction of meadow-peaty soil is neutral, in solonchak soils it is strongly alkaline, the humus content in solonchak soil is negligible (0.42), and in meadow-peaty-humus soil it is quite high (9.24). There is quite a lot of magnesium in saline soils (up to 29 mmol/100 g of soil), and nitrogen (1.10 %) in meadow-peat-humus soil. But there is a lack of phosphorus in all soils. The cluster is characterized by a high complexity of vegetation cover, expressed in a combination of phytocenoses of real (glycophytic), saline (halophytic) meadows, steppes, reed beds and woody shrub vegetation.