The results of studying the effect of fires on the biological properties of brown soils of xerophytic forests (Skeletic Leptic Cambisol) of the Utrish State Nature Reserve, Krasnodar Territory (crown fire of 2020), and burozem of mesophytic forests (Haplic Cambisol (Loamic)) of the Khamyshinsky forestry, Republic of Adygea (ground fire of 2018) are presented. Changes in the reaction of the soil environment, the content of organic carbon, and the activity of such enzymes as catalase, urease, phosphatase, and invertase involved in the cycle of carbon, phosphorus, and nitrogen have been studied. The reaction of enzymes to pyrogenic effects depends on the type of enzyme and the type of soil. A factor analysis was also carried out. The activity of catalase and invertase for two types of soils in a layer of 0–3 cm decreased by an average of 47%, while the reaction of phosphatase and urease differed depending on the soil type. Two years after the fire, the phosphatase activity of the surface layer of post-pyrogenic brown soils approached the control values; urease activity recovered more slowly compared to other enzymes. Four years after the fire, in the 0–3 cm layer, for the post-pyrogenic acid burozem, on the contrary, the values of urease activity approached the control values. An increase in pH values by an average of 30% and a decrease in the content of Corg by an average of 12% were also established for two types of soils. In the 3–10 cm layer, for brown soils, an average increase in the activity of all the studied enzymes was noted, while for acid burozem, on the contrary, a decrease. Factor analysis showed the presence of a relationship between the reaction of the soil environment, the content of organic carbon and the activity of enzymes, while the tightness and nature of the relationship differed depending on the type of soil. The results obtained indicate the influence of the edaphic features of the studied soils on the response of enzymatic activity to pyrogenic exposure.
The carbon reserves (C) and the rates of emission of greenhouse gases (CO₂and CH4) in peat soils of Western Siberia have been studied. The peat soils are typical for region oligotrophic ones (Histosols), but they develop in two contrasting bog ecosystems (a forested bog and an open bog), therefore, they differ significantly in modern vegetation cover, soil profile structure, hydrological and temperature conditions. It has been shown that the carbon reserves in the studied peat soils in the 0–50 cm layer are 9.3 and 6.8 kg/m² in the forested and open bogs, respectively. Measurements of CO₂and CH4 emissions were carried out by the chamber static method during the growing seasons from 1999 to 2014. The results showed that the studied soils release into the atmosphere the same number of CO₂(116.1 and 123.4 mg/(m² h) for soil in a forested and open bog, respectively), but at the same time significantly differ number of CH4 (0.57 and 2.66 mg/(m² h), respectively). This research has highlighted an important role of vegetation species composition and hydrological regime in estimates of carbon deposition and greenhouse gas fluxes from peat oligotrophic soils of bog ecosystems in the region.
The biomass and functional diversity of microbial communities were studied in the watershed, transit, and accumulative positions in catenas of virgin gray soils (Luvic Retic Phaeozems) and chernozems (Haplic Chernozems) of the “Belogorye” nature reserve and arable variants outside the reserve. Microbial biomass was determined by the substrate induced respiration (SIR) and the determination of the content of phospholipids. Multisubstrate testing of respiratory responses in the MicroResp system after the addition of amino acids, carboxylic acids and carbohydrates was carried out. It was established that in the virgin chernozem, microbial biomass decreased in from the watershed towards the accumulative part of the slope; in the gray forest soil, minimal values were in the transit part of the catena. In the plowed horizon of agrochernozems, it was close in all parts of the catena and 2–3.5 times less than in virgin chernozems. For the agro-gray soils, an increase in microbial biomass was fixed in the soils of the transit and accumulative parts of the catena. Cluster analysis of respiratory responses in the 0–10 and 10–20 cm layers identified two groups of the most demanded substrates. The first group in both layers included citric and ketoglutaric acids, the second – fructose and succinic acid. Ascorbic acid, sucrose, and glutamine were included in the first group in the 0–10 cm layer and in the second group (along with asparagine and glycine) in the 10–20 cm layer. In all virgin and arable catenas, an increase in metabolic diversity was noted from the watershed to the accumulative part of the catena. At the same time, plowing led to its decrease in the 0–10 cm layer: up to 1.5 times in chernozems and up to 4 times in gray soils. In the 10–20 cm layer, similar trend was observed, except for the agro-gray soil in the transit part of the catena, where the number of significant responses increased 3.6 times in comparison with the virgin variant.
There are only few studies in the world on ecotoxicity of urban dust as its ability to cause adverse effects to living organisms. The aim of the research is to assess the ecotoxicity of dust by the reaction of higher plants using a new approach, as well as to analyze the differentiation of microbial reaction on dust from recreational, residential and transport functional areas of three Moscow districts. The proposed approach of the urban dust ecotoxicity assessment by the modeling of dust transfer on urban soils proved its consistency and resolved the main methodological difficulty of biotesting – the issue of control choosing. Applying ryegrass (Lollium perenne L.), it was found that the annual volume of dust deposition on soils in Moscow does not perform toxicity, while a three-year volume suppresses plants up to 27% relative to the control. No significant differences between the phytotoxicity of dust in different functional areas was found, and phytotoxicity did not correlate with any of the studied properties of dust (organic carbon content, pH, electrical conductivity, moisture capacity, particle size distribution). In contrast to plants, the parameters of the vital activity of microorganisms in dust revealed differences between functional areas. Basal respiration and microbial dust biomass were maximal in the recreational areas of the city (3.1–7.2 μg C–CO₂g–1 h–1 and 314–435 μg g–1 respectively), decreasing by 27–71% in residential and 76–81% in the transport ones. Significant correlations of basal respiration and microbial biomass with organic carbon content were observed.
A comprehensive assessment of the structural and functional state of microbial communities of multi-temporal buried ancient soloids (a soil-like formation similar to soil but without genetically formed horizons) in open archaeological pits of ancient human sites located in the middle reaches of the Mzymta River on the Sochi Black Sea coast in the Akhtsu Grotto and Akhshtyrskaya Cave was carried out. Changes in the functional biodiversity of ancient soloids compared to the background (alluvial soils that form in close proximity to the studied soloids and have similar mesomorphological properties) are noted: a decrease in the specific metabolic work (W) of microbial communities by 1.2 times according to the method of multisubstrate testing and an increase in the instability of paleomicrobial systems according to the index of the rank distribution of the spectra of consumption of substrates d 1, which is typical for irreversibly damaged systems. The microbial community of ancient soloids has undergone a number of changes associated with anthropogenic activity. The analysis of the main absorption spectrum of substrates (MST method) showed that the microbial community of the soloid of the Akhtsu Grotto is oriented towards more intensive consumption of alcohols and amino acids, which suggests that organic matter of animal origin entered the cultural layer of the ancient human site. In the microbiome of the soloid of the Akhshtyrskaya cave the presence of lactotococci and bifidobacteria was found, which are extremely rare in soil and develop in conditions of excess carbohydrates on rich complex media, such as fermented meat and plant residues. Also, an increase in the content of keratinolytic fungi capable of decomposing keratin of hair, wool, feathers, etc. was found in the cultural layer of the cave site. Prokaryotic taxonomy in all the studied soils, with or without anthropogenic impact, was characterized by the predominance of the members of the Thermoleophilia clade and the families Gaiellaceae and Solirubrobacterales. Considering that these species require positive temperatures to develop, it suggests that the soils were formed in a mild climate. The Akhtsu grotto paleosols are a promising source of bacteria (genera Janthinobacterium, Lysobacter, Chitinophaga) that may have biotechnological potential.
