Articles

Abundance and diversity of soil saprotrophic bacteria complexes were monitored for two years on the territory of one of the large industrial cities of the European North of Russia, Syktyvkar. The work was carried out before and after quarantine in connection with the COVID-19 pandemic. The capital of Komi is characterized by a high population, and by tense environmental conditions according to the ecological standard. Studies were conducted in 2019—2020. Topsoils (0—10 cm) of urbanozems, horizon A in the park area in the urban space, as well as zonal undisturbed podzolic soil were analyzed. Comparison of the two)year monitoring results demonstrated a marked increase in the number and diversity of saprotro) phic bacteria complexes in 2020 both in urban and control soils (topsoil, 0—10 cm).

Detailed studies of Enterobacteriaceae demonstrated a decrease in the share of opportunistic (Enterobacter agglomerans, Citrobacter europaeus, Klebsiella oxytoca, Serratia marcescens, etc.) as well as fecal coliforms (Escherichia coli, Enterococcus faecalis) in urbanozems in 2020 — a consequence of a sharp and prolonged decrease in the anthropogenic impact on the environment. It can be viewed as a manifestation of the soil ability to “self-purification” when anthropogenic impact on the environment reduces.

The creation possibility of highly effective universal stimulating preparation for presowing seed treatment of various grain crops on the base of sorption)stimulating preparation (SSP), consisting of calcium bentonite (CB), humate (H), brewer’s yeast autolysate (BYA), and gibberellin (Gibb) is studied. The introduction of some non)ionic surfactants into the preparation composition results in the disintegration of bentonite aggregates into individual montmorillonite particles and an increase in the active surface of the sorption complex. It gives an opportunity by increasing the gibberellin concentration to improve the SSP efficiency in 1,5 times. As a result, 5)component composition (SSP-5), including CB, H, BYA, Gibb, PEG, is developed, and its efficiency on spring wheat of Lisa cultivar on sod)podzolic soil is 56%.

The introduction of other BAS into the preparation to make up a possible lack of these compounds in seeds showed that with an increase in the stimulation of some seeds for other ones, the supplementary adding of phytohormones reduces the overall effect. These data allow suggesting that it is not possible to create universal preparation highly effective for all seed.

Since gibberellin stimulates seeds development much more often than other phytohormones, we tested the SSP-5 action on seeds of different cultures and cultivars. It is established that, in most cases, this preparation effective for seed stimulation, but the efficiency values from its application vary markedly.

The simulation model of seasonal dynamics of ¹³⁷Cs in the components of the snytevoy oak forest ecosystem EcoradOak_CS_FW was further developed, which now includes first- and second-order consumers. The radiocesium redistribution in a full-scale food web of   a forest ecosystem of the type “soil—vegetation cover—herbivores—predators” is modeled. The algorithm used in the model allows us to take into account the influence of soil, meteorological, phenological and physiological factors on the behavior of radionuclide in the food web and predict radiological situations under various conditions of radioactive fallout. Data   on the contamination of animals with radiocesium obtained using the model are used to calculate the dynamics of the internal dose. The results of modeling can be used in the rationing of forest products of deciduous forests. The model is also applicable to the study of potassium redistribution in the trophic chain of a deciduous forest ecosystem.

In south taiga, as the former hayfields overgrow, the biomass of herbaceous layer decreases even before the formation of a closed tree stand. In the topsoil, increase of actual acidity   was observed, which was adequately reflected by the species of living ground cover;   a more distinct trend was revealed for light soils. The content and reserves of organic carbon in the soil of the hay meadow, where the mowing was preceded by perennial grazing, is rather high in comparison with the soils of hayfields without prior grazing. In general, after grass mowing stop, the content and reserves of organic carbon in topsoil decrease. Long)term cattle grazing slows down the postagrogenic dynamics of organic matter in meadow soils.

The litter properties of Moscow State University urban stands with a different type of  care, from lack of care to regular care, were studied using birch stands, lime stands and maple stands as examples. Simplification of the vertical structure as a result of care increases the open space inside the stands, changing the degree of shading and wind regime. For park stands, the special role in litter formation belongs to lateral wind transfer and care regularity, these factors influencing on litters pool and fraction composition. The use of stand care is accompanied by the withdrawal of from 50 to 90% of the stocks of litter, which leads to decreasing recirculation of organic matter and ash elements in urban ecosystems.

The characteristic of symbiotic relationships is presented on the example of vesicular-arbuscular mycorrhiza in the case of Trifolium pratenseL. at different succession stages of meadow phytocenoses. It is shown that the functional potential of symbiosis changes in the course of succession and is fully revealed under conditions of an undisturbed climax community. The fundamental possibility of biological diagnostics of the state of phytocenosis using discriminant analysis according to the indices of an individual legume plant, taking into account the symbiotic potential, has been demonstrated.

Under the conditions of a model vegetation experiment (30 days), the responses of microbial communities of agro-soddy-podzolic soil of two sites (Chashnikovo, Moscow region) with different organic carbon content (Corg 3,86 and 1,30%) to polymetallic pollution with heavy metals (HM: Cu 660, Zn 1100, Pb 650 mg/kg) and treatment with biochar (5%) and lignohumate (0,25%) Methods of classical inoculation on Czapek agar and analysis of soil lipid profiles by gas chromatography—mass spectrometry, an assessment of the differences in abundance colony forming units (CFU), the biomass of fungi and bacteria, the diversity of cultivated fungi in humus-rich and humus-poor soil. HMs did not have a significant effect on the number of CFU and the number of cultural-morphological types of colonies, but they reduced the biomass of fungi and bacteria in both soils, while this decrease was much more pronounced in a weakly humus soil. In addition, the differences between the soils manifested themselves in a different increase in the proportion of resistant melanized forms of fungi under the influence of HM in a highly humified soil — by 25,9%, and in a weakly humified soil — by 45,7%. The sensitivity and universal significance of structural indicators as indicators of the stability of microbial complexes under chemical contamination of soils of different humus content are discussed; among the studied, the most sensitive and reliable indicators include the assessment of the proportion of melanized fungi.

The characteristic of typical and humus petrozems of the most high-altitude belt zone of the Khibiny, formed under three predominant types of plant groups corresponding to different stages of primary succession, is presented. For these soils, there is no differentiation of the profile by the content of most elements, with the exception of phosphorus, which is concentrated in the surface organogenic horizons. According to many chemical and phy sicalchemical properties, the soils of the char belt are close to Entic Folic Podzols formed in the underlying mountain-tundra belt under shrubby vegetation. The biological activity of petrozems below or is comparable with this parameter in the soil of shrub tundra. It was found that as the structure of vegetation becomes more complex, the activity of microorganisms increases and the organic matter of the soil stabilizes. Overall, the microbial community of petrozems well adapted to extreme conditions.

Indicators of cadastral value of soils in agroclimatic subzones of agrolandscapes of the Irkutsk region are determined. The sensitivity of cadastral value calculation approaches to various soil and geographical conditions is shown. Low values of the cadastral value of agricultural land are due to low values of agroclimatic potential.