Soil and Plant Cover and Microbial–Biomorphic Assessment of Ecosystems in Coastal Depressions of Highly Mineralized Drainless Pulsating Lakes of Dauria (Southeastern Transbaikalia)

Abstract

The soils, vegetation cover, and microbiota of coastal depressions of highly mineralized drainless chloride lakes in southeastern Transbaikalia (Dauria and Lake Bab’e) have been comprehensively studied for the first time. It is revealed that the lakeside ecosystems of the steppe zone are formed under cyclic changes in the level of lakes and the resulting change in the lake water chemical composition. The aeolian factor exerts a certain influence. The dynamic properties and substance composition of soils of superaqual–subaqual, superaqual, and eluvial–superaqual positions have been studied. The current continental salinization of various chemical composition and hydrogenous carbonization has been revealed there. A study of the spatial pattern of phytocenoses and their species composition, depending on location in the relief of lakeside depressions, soil conditions, and halogenesis, shows the allocation of pioneer hyperhalophytic and halophytic communities to quasigley solonchaks. Within the superaquatic part of the lakeside depression, plant communities are predominated by halophytes and mesophytes with the participation of glyco-oligohalophytes and mesoxerophytes. The feather-grass–forb–leymus (Leymus chinensis, Artemisia frifida, Bupleurum bicaule, and Stipa krylovii) steppe with the participation of mesophytes and xerophytes is formed on light-humus soils, similar in composition to zonal steppes. It has been revealed that various microbiomorphic complexes are formed in dynamically evolving lakeside soils, depending on abiotic factors. Highly mineralized chloride lake waters contribute to the formation of similar microbial communities in the bottom sediments of Lake Bab’e and in highly saline horizons of the quasigley solonchak. A large proportion of unidentified prokaryotes has been found in all soil samples. This important unstudied microbial component is present at the level of the Bacteria domain in solonchaks (to 22%), saline humus-quasigley soils (to 15%), and light-humus saline soils (to 16%). The microbiome structure in humus–quasigley soil is characterized by the presence of halobacteria and crenarchaeotes. A significant proportion of taxa involved in carbon and nitrogen cycles and playing an important role in global biogeochemical cycles has been revealed in light-humus saline soil. Halobacteria are not revealed in this type of soil due to the insignificant content of easily soluble salts in the humus and transitional horizons.