Moscow University Soil Studies Bulletin. 2021. 2.

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.

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 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.

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.

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.

Mineralization rates of soil organic matter (SOM) decomposition of non-remediated and remediated oil)polluted, as well as background soils from the main types of West Siberian middle taiga’s ecosystems were measured in laboratory experiments. Rates of SOM mineralization were measured by alkali absorption of CO₂ released from wet soil samples at 20°C (basal respiration). Because of linear character of cumulative curves of CO₂ release SOM mi neralization rates were expressed by mineralization index K1 equal to the annual amount of CO₂ released per 1 gramm of soil. K1 values varied in a range 0,123—1,578 mg СО₂/g/day. Highest value was found in background forest soil, lowest — in oil-polluted peat soil with extremely high oil content (544 g/kg). K1 values negatively correlated (K = –0,57) with oil content. SOM mineralization rates in remediated oil)polluted peat soils varied in a range — 0,31—0,85 mg СО₂/g/day