Yakutin M.V., Andrievskii V.S., Kosykh N.P. 2019. [Peculiarities of parallel successions of microorganisms and oribatid mites during the process of floodplain soil evolution in the southern tundra subzone of Western Siberia] // Euroasian Entomological Journal. Vol.17 (for 2018). No.6: 445–451 [in Russian, with English summary].
Institute of Soil Sciences and Agrochemistry, Russian Academy of Sciences, Siberian Branch, Lavrentiev Prospekt 8/2, Novosibirsk 630090 Russia.
ABSTRACT. The study has been conducted in the middle stream of the Taz river (North of Western Siberia). Alluvial sod soil is characterized by a absolute absence of oribatid mites and relatively low values of microbial biomass and basal respiration, and the level of metabolic coefficient gives evidence about the existence in these extreme conditions of a stable microbial community. It is shown that in the process of evolution of alluvial sod soils in the tundra zone on the way of transformation into automorphic zonal tundra soils oribatid mites appear and their community is already a multi-species one. Based on the quantitative indexes of this community (species richness and abundance) and qualitative ones (structure of dominance and presence of the euritope polyzonal species-dominant), the investigated tundra ecosystem can be recognized as a generally unfavorable habitat for the oribatid mites community, which, apparently, is a common feature for the tundra ecosystems of Siberia in general. At the same time, the microbial block of tundra soil is characterized by a much higher biomass and basal respiration level than such of alluvial sod soil, and the level of metabolic coefficient gives evidence about the existence of a stable microbial community, but, apparently, significantly transformed in comparison with such of alluvial sod soil. It is concluded that the existence of zoo-microbial block as the basis of the destruction link of the biological cycle in the tundra zone soils is possible, apparently, only in the automorphic proper tundra soils. Extreme hydromorphic conditions of alluvial soils in the tundra zone do not allow oribatid mites to settle in them and therefore they do not take part in the decomposition of plant litter in such soils and the role of microorganisms in this process accordingly increase.
KEY WORDS: Western Siberia, southern tundra, succession, alluvial sod soil, tundra gley soil, microbiomass, basal respiration, metabolic coefficient, oribatid mites abundance, species richness, destruction block, transformation