THE INFLUENCE OF SPRUCE STANDS ON THE PHYSICOCHEMICAL PROPERTIES AND MICROBIAL COMMUNITIES OF PERMAFROST MEADOW-CHERNOZEM SOILS
A. P. Chevychelov, N. P. Kuzmina, O. G. Zakharova, S. V. Ermolaeva, A. A. Alekseev
Federal state budgetary institution of science Federal research center "Yakut Scientific Centre of the Siberian Branch of the Russian Academy of Sciences", Institute for Biological Problems of Cryolithozone, Russian Academy of Sciences, Siberian Branch, Yakutsk, Russian Federation
Keywords: cryogenic soils, composition and properties, microorganisms, transformation
Abstract
The influence of spruce ( Picea obovata Ledeb.) stands on the change in morphological characteristics, physicochemical properties, state of organic matter, as well as the qualitative and quantitative composition of the microbiocenoses of cryogenic meadow-chernozem soil formed under meadow-steppe vegetation in Central Yakutia was studied. By means of the complex application of soil, microbiological, statistical research methods, all changes that occurred in the original cryogenic soil were identified and assessed. Thus, over a 45-year period of forest vegetation influence, the morphological profile of the original meadow-chernozem soil (Luvic Chernozems Sodic), which had the form: Аv, ca-Aca-ABca-Bcа-BCca-Cca, was transformed into the profile of cryogenic humus-carbonate soil (Calcic Cryosols Eutric), which was already characterized by the following structure: O-А0-A-ABca-Bса-BC-Cca. Over the noted period, a forb-green moss vegetation cover was formed on the surface of the forest soil, as a result of which the depth of seasonal thawing decreased. The physical-chemical properties, humus composition and the state of microbiocenoses of the studied cryogenic soils also changed significantly. Thus, in the meter-thick layer of these soils, the weighted average pHH2O value decreased from 9.0 to 8.6, and the content of organic C and total N, respectively, increased from 0.79 to 1.72 % and from 0.03 to 0.13 %. At the same time, more mobile humus was formed in the humus profile of the cryogenic humus-carbonate soil, when the total amount of humic acids increased to 65.6-86.0 %, and the proportion of non-hydrolyzable residue decreased to 14.0-34.4 %. Also, this soil turned out to be the richest in microorganisms, where their total number was 2.4 ± 1.3×106 CFU/g, while in the original soil it was only 5.8 ± 3.1×105 CFU/g. Moreover, if actinomycetes (34 %) and micromycetes (29 %) were relatively predominant in the first soil, then oligonitrophilic bacteria (37 %) and ammonifiers (27 %) were predominant in the second.
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