The materials of our studies on the taiga shrew (Sorex isodon Turov, 1924) in the NorthEast of the European Russia, a poorly studied species of small mammals of the region, are summarized. Its distribution is shown to generally coincide with the northern border of the taiga zone. The optimal biotopes are grass spruce forests (only for them the values of the biotope fidelity coefficient are positive). The numbers of taiga shrews in lowland localities are 0–2.4 individuals, in foothill habitats it increases up to 4.4–8.6 individuals and reaches maximum values on the western slope of the Northern Urals (28 individuals per 100 cone-nigths). The formation of the numbers of the species is much influenced by the landscape conditions of the territory: the ratio of habitat types and their areas. An increase in the area of grass forests leads to an increase in the abundance of taiga shrews. 

Landfill biogas contains large amounts of toxic and harmful impurities and may be a source of microbiological contamination of both the complex municipal waste landfill itself and adjacent territories. This paper uses modern biotechnologies designed to protect the environment, to study the quantitative and qualitative composition of biogas for harmful factors, as well as for harmful substance removal from biogas. An assessment was made of air purification in the premises near landfills and adjacent territories using green plantations and a biological system based on an apparatus-biological complex for purification from microbiological contamination. The data obtained in our laboratory studies show that such apparatus-biological complexes can reduce the negative influence on the personnel and workers at operative points and the inhabitants of adjacent territories by air purification. 

The group variability of morphological features of the leaves of Betula pendula Roth was studied in the gradients of adverse weather conditions and technogenic soil transformation. The studies were carried out on the territory of the Tagil zone of the Middle Urals in 2016–2019. It has been revealed that most of the studied leaf traits have an average level of variation, while a high one is characteristic of the shape index, and a low one is characteristic of the leaf blade index and the angles between the main and lateral vein of the first order, located in the middle and upper parts of the leaf. In the gradient of deterioration of weather conditions, the variability of the features increases, whilst it decreases in the gradient of technogenic soil transformation. The morphological features making the greatest contribution to the variability of the size and shape of the leaf were identified by the method of principal component analysis. Leaf variability is mainly determined by dimensional features. Allometric features are more stable. To assess the resistance of an organism to adverse factors, it is proposed to use the stability coefficient, which reflects the number of trait transitions from one level of variability to another one. This indicator increases both in the gradient of technogenic soil transformation and in the gradient of unfavorable weather. 

This article is devoted to the study of the possibility of determining the ecological density of game animals according to winter route censuses. Determining the density of game animals is a prerequisite for determining their prey quotas. The most valuable parameter characterizing population estimation of specific species of game animals is ecological density. She calculated for the area actually inhabited by a particular animal species. The population density, calculated on the area suitable for the type of land, is widely used in the practice of domestic hunting. Territories with feeding and protective properties for this species are considered suitable sites. The materials of winter route counts confirm that the territories suitable for any animal species are not always completely populated by it, and the territories recognized as unsuitable are visited by these animals. Tracking activity of game animals is recorded both in areas that are considered suitable for the species, and in areas that are not typical for it. The territory of the animal during the day is the area lying inside the minimum convex contour drawn around the daily track of this animal. In this case, as the territory occupied by some animal, we can consider the territory obtained by combining all the minimum convex contours drawn around all daily traces left by this animal for a certain time. The union of the minimum convex contours drawn around all daily traces left by all animals of a given species during the period of accounting work can be considered as the territory inhabited by them at this time of the year. The crossing of a track by a route is a random event. Therefore, to determine the ecological density of a species according to the winter route censuses data, it is necessary to apply the probability theory. 

The purpose of the work is to assess the state of Anura populations living in an anthropo-genic territory according to a set of indicators of the body’s immune homeostasis. The objects of the study were Pelophylax ridibundus (Pallas, 1771) and P. lessonae (Camerano, 1882), living in the natural populations of reservoirs in Nizhny Novgorod. Priority chemical pollutants of the water bodies were determined by spectrophotometry. Species were identified using a multiplex PCR test system. The identification results were confirmed by sequencing of the mitochondrial ND2 gene and a fragment of the SAI protein. We counted the numbers of erythrocytes and leukocytes, determined the leukocyte profile and the level of immune complexes in all frogs. An excess of the water quality standard for the content of heavy metals was revealed in all the water bodies. Molecular genetic diagnostics showed the presence of both “pure” P. ridibundus and individuals with introgressive mtDNA of the Anatolian form of the lake frog (P. cf. bedriagae) in the sample of lake frogs. In the sample of pond frogs, all studied individuals had only species-specific mt- and nDNA markers of P. lessonae. P. ridibundus differed from P. lessonae by an increased content of erythrocytes, neutrophils, basophils, small immune complexes, and a reduced content of lymphocytes. The revealed changes in the immunohematological parameters of green frogs were caused by the complex henotoxic effect of pollutants in the water bodies. A decrease in the lymphocytes/eosinophils ratio index was shown with an increase in the concentration of nitrites, an increased activity of humoral immune responses in conditions of sulfate pollution of the aquatic environment, an increase in the proportion of myelocytes in the blood of frogs with an increased concentration of manganese and nitrates in water. Under conditions of environmental stress, the blood regulatory systems of frogs reflected a stress-induced reaction, which was more pronounced in the body of lake frogs compared to pond ones. 

Our studies of the distribution and abundance of the yellow-breasted bunting (Ocyris aureolus) were carried out on the territory of the Arkhangelsk region and in certain bordering areas of the Komi Republic in 2001–2022. A total of 57 meadow and meadow-swamp territories were surveyed, and a number of them – repeatedly in several years. In 2001–2011, the yellow-breasted bunting was found in almost all the surveyed territories, except some dry meadows and extreme northeastern floodplain lands in the lower reaches of the Mezen river. But already in these years, there were trends towards a decrease in its numbers, as indicated by the records carried out in the floodplain of the Pinega river for several years. In subsequent years, the yellow-breasted bunting was recorded on vast grasslands in the floodplains of large rivers only. A relatively high density was observed only in three (out of 35 surveyed) sections of flood meadows, in the floodplains of the Northern Dvina river and Vaga river. In most of the territories where it was found, only 1–3 individuals were recorded. In addition to dry meadows, it has ceased to occur in small-area floodplain meadows. Since the habitat conditions of the yellow-breasted bunting at the northwestern borders of its range have not changed significantly, the cause for this decrease in its numbers there can be considered the deterioration of habitat conditions during the flight and wintering. 

Manure effluents (ME) of livestock enterprises represent a rich nutrient medium for the development of various aerobic microorganisms (MO). During the biodegradation of the organic components of ME, a wide range of odor-forming substances (OFS) and greenhouse gases enter the atmospheric air. The intensity and main directions of ME destruction depend on the composition and amount of microbiota. A solution of sodium hypochlorite can be used to suppress the decomposition of the biogenic components of ME. In the course of our research, it was found that the introduction of 0.005% active chlorine into the liquid fraction of ME (pH ~ 6.8; humidity ~ 99.1%) leads to a decrease in the numbers of putrefactive microbiota, namely: Bacteroides, Clostridium, Escherichia coli, Pseudomonas, Sarcina ventriculi, and Peptostreptococcus anaerobius. The corresponding ammonifiers are actively involved in the biodegradation processes of organic substances to form acetic acid, isovaleric acid, butyric acid, indoles, skatoles, ammonia, hydrogen sulfide, mercaptans and others. The numbers of microbiota not making a significant contribution to the production of OFS (Saccharomyces cerevisiae, Rhodotorula glutinis, Lactobacillus ssp. and others), on the contrary, increased. The numbers of some producers of volatile fatty acids (VFA), namely: Anaerococcus prevotii, Acidaminococcus, Prevotella spp. etc. increased. However, this did not affect the intensity and nature of the ME odor, which can be explained by the formation of non-volatile VFA salts at pH above 7.0. The numbers of Staphylococcus aureus, Staphylococcus epidermidis, Klebsiella sp., Proteus ssp., Alistipes putredinis, Bifidobacterium ssp., Candida tropicalis, and Candida albicans almost did not change when NaOCl was added to ME. As a result of the microbiota transformation, the total emission of gaseous substances, whose main components are the greenhouse gases CO2 and CH4, decreased by more than 17%. The unpleasant odor intensity has significantly decreased. A NaOCl solution can be used to treat ME in manure storage baths. The introduction of the practice of treating ME with this biocide is facilitated by its availability, low cost and safety for the environment.