Soil and plant cover and microbial-biomorphic assessment of ecosystems within coastal depressions of highly mineralized drainless pulsating lakes of Dauria (Southeastern Transbaikalia)
V. I. UBUGUNOVA1, L. L. UBUGUNOV1,2, A. S. SYRENZHAPOVA2, E. Yu. ABIDUEVA1, T. A. AYUSHINA1, A. D. ZHAMBALOVA1, T. E. TKACHUK3,4
1Institute of General and Experimental Biology SB RAS, Ulan-Ude, Russia
2Buryat State Agricultural Academy named after V. R. Filippova, Ulan-Ude, Russia
3Transbaikal State University, Chita, Russia
4Daursky State Nature Biosphere Reserve, Nizhny Tsasuchey, Russia
Keywords: Southeastern Transbaikalia, highly mineralized chloride lakes, lakeside ecosystems, soils, salinization, vegetation, microbial-biomorphic complexes
Abstract
Complex studies of soils, vegetation cover, and microbiota of coastal depressions of highly mineralized drainless chloride lakes in Southeastern Transbaikal Region (Dauria, Lake Babie) were performed for the first time. It was revealed that the lakeside ecosystems formed within the steppe zone under cyclic changes in the level of lakes and the resulting change in the lake water chemical composition. The eolian factor has a certain influence. The dynamic properties and material composition of soils of superaqueous-subaqueous, superaqueous, and eluvial-superaqueous positions have been studied. Current continental salinization of various chemistry and hydrogenous carbonization has been revealed there. The study of the spatial structure of phytocenoses and their species composition, depending on relief location in lakeside depressions, soil conditions and halogenesis revealed the confinement of pioneer hyperhalophytic and halophytic communities to quasigley solonchaks. Within the superaquatic part of the lakeside depression, plant communities grow with a predominance of halophytes and mesophytes with the participation of glyco-oligohalophytes and mesoxerophytes. The feather-grass-forb-leymus (Leymus chinensis, Artemisia frifida, Bupleurum bicaule, Stipa krylovi) steppe was formed on the light-humus soils, similar in composition to zonal steppes, with the presence of mesophytes and xerophytes. Various microbiomorphic complexes have been established to be in dynamically evolving lakeside soils, depending on abiotic factors. Highly mineralized chloride lake waters contribute to forming of similar microbial communities in the bottom sediments of the Lake Babie and highly saline horizons of the quasigley solonchak. At the same time, a large proportion of unclassified prokaryotes were found in all soil samples. This important unstudied microbial component is present at the level of the Bacteria domain in solonchaks (up to 22 %), saline humus-quasigley (up to 15 %), and light-humus saline (up to 16 %) soils. The microbiome structure in humus-quasigley soil is characterized by the presence of halobacteria and krenarcheotes. A significant proportion of taxa involved in carbon and nitrogen cycles, and play an important role in global biogeochemical cycles, have been established in light-humus saline soil. Also, halobacteria were no revealed in this type of soil due to insignificant content of easily soluble salts in the humus and transitional horizons.
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