MICROBIOLOGICAL CHARACTERISTICS OF INTACT AND POST-AGROGENIC TUNDRA SOILS (ON THE EXAMPLE OF THE ARCTIC ZONE OF THE KOMI REPUBLIC)

• Main Authors: Vera Kovaleva, Svetlana Deneva, Elena Lapteva
• Format: Article
• Language: English
• Published: Karelian Research Centre of the Russian Academy of Sciences 2020-05-01
• Series: Transactions of the Karelian Research Centre of the Russian Academy of Sciences
• Subjects: agricultural regime; postagrogenic ecosystem; meadow; microbial community; microbial biomass; potentially viable bacterial cells; fungal mycelium; mineralization coefficient
• Online Access: http://journals.krc.karelia.ru/index.php/ecology/article/view/1162
• ISSN: 1997-3217; 2312-4504

<p>We studied evolution aspects of agrogenic and post-agrogenic soil formation under conditions of tundra zone. In order to perform a comparative analysis, we studied soils of intact dwarf birch willow moss tundra (cryometamorphic gleezem) and that of herb-grass meadow (gleezem cryometamorphic postagrogenic) formed at the place of long-time seeded meadow operated for 35 years. The process of agrogenic tundra soil transformation includes transformation of the upper part of the original soil profile under the influence of mechanical stress (plowing, harrowing), the application of agromeliorants (calcareous materials, mineral and organic fertilizers) and the development of soddy and humus accumulative processes, which is accompanied by an acceleration of the decomposition of plant residues with the accumulation of nutrients in the upper mineral part of the profile. Removing the agricultural regime causes the introduction of native plants and mosses into the postagrogenic phytocoenoses and the following recovering of zonal vegetation. At the time of the research, the post-agrogenic ecosystem retained the general appearance of a meadow plant community, and its soil showed signs of a transformed soil (the presence of humus-accumulating horizons with a high content of nutrients). At the studied soils, we determined the number of bacteria and fungal spores, and the length of mycelium. The functional state of Prokariota was estimated by the ratio between bacteria with intact cell membrane (living cells) and those with damaged cell membrane (dead cells). We also characterized the ecotrophic structure of microbial communities. The general pattern of soils under study is a maximal number of microorganisms in the upper organogenic or organomineral (humus accumulative) soil horizons, where the majority of Prokariota is presented by living bacterial cells. The total number of bacteria in the soil of post-agrogenic ecosystem was by 1,5 times higher than that of tundra community. By the number of fungal spores (93,8±12,7 mln. cells per g of soil) and the mycelium length (1017,4±123,4 m/g of soil), the leading place is occupied by tundra soil. Postagrogenic soil shows a decrease of these parameters by 3 times. Low coefficients of mineralization indicate slow processes of mineralization of organic matter in both tundra (0,6) and postagrogenic (0,7) ecosystems. The latter shows higher level of trophicity and biogenicity.</p>