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An effect of molting anseriform birds on structure and elemental composition of phytoplankton (seston) was evaluated in 20 Arctic lakes of the Taimyr Peninsula. In lakes (lake area) inhabited with ~50-700 birds of 6 species, an average stoichiometric ratio N : P (mol: mol) was statistically significantly lower, than in lakes without anseriforms: 15.8 ± 1.4 и 22.4 ± 2.7, respectively. Besides, there was a tendency of higher average specific electrical conductivity in lakes with the birds, 113 ± 32 µS/cm, compared with those without anseriforms, 60 ± 18 µS/cm. The differences observed could be likely explained by an effect of guanotrophication, namely by a flow in water of metabolites of molting anseriforms. Total biomass of phytoplankton and proportions of algal taxa and cyanobacteria in the total biomass did not differ statistically significantly in lakes with and without molting anseriforms. Thereby, under the guanotrophication, the main threat of eutrophication was absent: an increase of biomass of cyanobacteria causing nuisance “bloom” of water. Moreover, an opposite tendency occurred: in lakes with molting anseriforms, the proportion of cyanobacteria in total biomass of phytoplankton was on average lower, than that in lakes without the birds, 16.2 ± 5.3 and 30.8 ± 9.3 %, respectively. Thus, a hypothesis was confirmed, that an artificial guanotrophication should be regarded as a suitable ecotechnology for an increase of productivity of oligotrophic Arctic lakes.

Within the ecological direction of studying humus using traditional methods and terms, the peculiarities of the transformation of organic matter of peat eutrophic soils (Hypereutric Sapric Histosols) and peaty gleezems (Eutric Histic Gleysols) 20 years after a forest-peat fire are discussed. The object of the study was the green moss-hypnum spruce forests (Picea obovata Ledeb.) of eastern slope of the Kuznetsk Alatau (absolute height 622 m). The composition of organic matter of pyrogenic soils (0-30 cm) is characterized by high variability (coefficient of variation 12-92 %). According to the factor analysis, 76 % of the total variance is due to a combination of humic substances, 24 % - polysaccharides. Using the cluster analysis procedure, we identified two groups of objects whose statistical reliability was confirmed by discriminant analysis. Soil clusters reflect the peculiarities of pyrogenic processes - underground focal smoldering, below the point of ignition, and open intense and medium strength fire. Relative to the background carbon content of 41 % (peats not covered by fire), its amount decreases to 26.5 and 13.4 %, respectively. At the same time, there is an almost equal formation of humification products (∑GC + ∑FC) - 55.4 and 53.7 % due mainly to fulvic acids (Cgc/Cfc 0.2-0.6). The peculiarities of the thermal effect are occurred mainly at the fractional level. The specificity of underground smoldering is an increased yield of fulvic acids of the first fraction, free and loosely bound to R₂O₃. An open fire is accompanied by the predominant formation of humic and fulvic acids associated with calcium. According to standardized coefficients of canonical analysis, the first and second fractions of humic and fulvic acids make the greatest cumulative contribution to cluster discrimination, the maximum personal weight is HC-2, FC-1 and FC-2. Based on previously obtained information about the group composition of buried peats and the important role of anaerobiosis in the formation of humic acids, which are more correspond with the restored nature of the substance compared to fulvic acids, it can be assumed that peat genesis continuing in the area of the fire can cause the transformation of fulvate humus into fulvate-humate and/or humate. In the case of burial of a pyrogenic peat layer of 0-30 cm, this can happen in about 270 years, based on the rate of linear growth of peat in the spruce forests of the Kuznetsk Alatau - 1.12 mm/ year. The research results confirm the validity of the traditional division of humic acids into fractions.

According to the scheme of age periodization of plant ontogenesis proposed by T. A. Rabotnov and A. A. Uranov, about a dozen of main age (ontogenetic) states are distinguished. Each population sample represents an ordered series of frequencies of occurrence of plants at these states - the so-called ontogenetic spectrum (OS). Various OS statistics are available according to the form of the OS, reflecting a greater or lesser representation of young, mature or old plants in the population and allowing to represent the temporal dynamics of the population. The Excel Ontogenetic Spectrum (ExOS) package presented allows their automatic computation and analysis. The input data are the numbers or frequencies of ontogenetic states in the sample. Output data: classifications of OS and cenopopulation types according to various criteria, population-ontogenetic indices; for multiple population samples - similarity (distances) between them and their ordination on "delta-omega" axes; the corresponding diagrams are captured authomatically.

Presented is a description of the distribution of terrestrial vertebrates in the northeastern part of the Kanin Peninsula (67°50′47′′ N, 46°20′40′′ E) based on the results of their counts conducted in July 2021. In total, 1 amphibian species, 1 species of reptiles, 57 species of birds and 6 species of mammals were recorded. The vertebrate fauna of this region, located in the dwarf birch tundra zone, is characterized by the presence of boreal species such as the viviparous lizard Zootoca vivipara Lichtenstein, tufted duck Aythya fuligula (L.), common goldeneye Bucephala clangula (L.), common crane Grus grus (L.), common sandpiper Actitis hypoleucos (L.), brown bear Ursus arctos L. and European elk Alces alces L. For the viviparous lizard, this is the northernmost known locality so far. Favorable factors for the distribution of boreal species in this area, in our opinion, are its location on the southern slope of the plateau-like ridge Kanin Kamen, the ruggedness of the relief, primarily deep river valleys with wind-protected and well-heated sides. A tenfold decrease in the density of placement of brood burrows of the Arctic fox Alopex lagopus L. was established in comparison with the 40-50s of the last century, due to the activation of cryogenic processes in permafrost, as a result of which the burrows of this predator, arranged in loose soils, are destroyed.

Despite more and more data on the Arctic biotic communities even the principal course of their transformation remains unclear. In this concern the profound interest is related to differences in population dynamics of geese, lemmings and ruminants covering more than 98 percent of the Arctic terrestrial ecosystem recycling and competing on the specialization ground for the same food resources. Comparing 15 species of the taxa we showed that grades of their morphophysiological adaptation to phytophagy are matched to empirical estimates of their food selectivity, thereby describing their trophic specialization distribution. Thus in the Arctic herbivore communities the selectivity distribution is so stable as specialization. The trophic specialists include muskox and snow goose in the first place, while the generalists are lemmings and smallest black geese. The specialist populations have mainly higher size and/or growth rate than the generalist populations have. It may be concluded that interspecific competition influence contemporary transformation of the Arctic herbivore communities much stronger than such environmental factor as global warming and human activity do.

The 45-year-long observations of variations in the musk deer abundance in the Ussurisky Nature Reserve are summarized. An analysis of winter route censuses has made it possible to assume these variations to be related with the emergence of a “new predator”, sable. The decrease in the musk deer abundance in the reserve occurred simultaneously with an increase in the sable abundance and a decrease in abundance of alternative food supplies for medium- and small-sized predators. From the early 2000s until the present time, the musk deer abundance in the reserve has remained at a level of only “presence” of the species in the fauna.

In the current article, the authors study small mammal species composition and population structure of the northern taiga landscape of the Nadym Hills (Yamal Nenets Autonomous Okrug, Russia). Special attention is given to catenae regularities of the intralandscape differentiation. Five micromammal species (Cl. rutilus, S. caecutiens, S. araneus, A. oeconomus, E. sibiricus), typical for the Western Siberia northern taiga subzone, were caught in different north-western parts of the catena (at the flat interfluve (placor), saddle, slope, flood plain). Red-backed mice Cl. rutilus outnumbered other species in all catena locations and in the landscape on the whole. Other species codominate in certain locations with an exception of S. araneus being common only at the placor. On the whole, over the area under study and in the higher locations of the catena, Cl. rutilus and S. caecutiens make up the core of small mammal communities. Along the hill slope - from the placor to the flood plain - the overall micromammal abundance and dominating species abundance decline gradually. A settled breeding small mammal population is present in all catena locations. The micromammal community composition, structure, and characteristics change along the slope in accordance with the changes in the territory afforestation, moistening, plant species richness, vegetation structure, microtopography. Due to harsh climate, the small mammal communities of all catena locations and whole area under scrutiny show low indices of diversity, evenness, and sustainability, high dominance index, but on the whole their structure is undisturbed and characteristic of natural subarctic communities, being indicative of the communities’ stability.

An analysis of depth-profile and spatial variations of the stable carbon isotopic composition of soil organic matter is presented to identify the main factors that determine the dynamics of organic carbon in the mountain-depression environments of the Baikal region. Soil organic matter is characterized by δ¹³С values from -29,6 to -24,9 ‰. Changes in δ¹³C values in the altitudinal profile correlate well with changes in landscapes and reflect the influence of climatic factors on13C discrimination during photosynthesis of C3 plants. The heaviest stable carbon isotopic composition characterizes the soils of subalpine and steppe landscapes. In taiga soils, depletion of the isotopic composition by¹³C is observed. To compare the soil carbon turnover intensity δ¹³C values were regressed linearly against log-transformed carbon contents yielding absolute values of these slopes (β). The distribution of β values in the altitudinal profile suggests a reduced intensity of carbon turnover in the soils of the steppes and the subalpine belt due to the limitation of these soils in terms of moisture and temperature, respectively. Under the taiga conditions characterized by more favorable ratio of temperatures and humidity the dynamics of soil organic matter is controlled mainly by the litter quality and the nitrogen availability.

The work presents the results of studies of the emergence of amphibiotic insects from the old beaver pond on the Yuzhny stream of the “Privolzhskaya lesostep’” reserve in the Upper Khoper basin. For insects from 34 families and 8 orders, the indicators of abundance, biomass, frequency of occurrence are given, the timing of their emergence in different parts of the pond is indicated. The dominant and common species were identified - chironomids Paramerina cingulata (Walk.), Cricotopus silvestris (F.), biting midges (Bezzia bicolor (Mg.), chaoborids Chaoborus flavicans (Mg.) and mayflies Cloeon inscriptum (Bgtss.). The intensity of the emergence of insects was 12.10 ind./m² per day, the average daily transfer of biomass was 49.23 mg/m² per day. The analysis of the fatty acid composition and content of the main biogenic elements in adults of amphibiotic insects was carried out. The results of calculations of the removal of energy and matter, including biogenic elements (carbon, phosphorus, nitrogen) and polyunsaturated fatty acids during the emergence of insects from various orders (Ephemeroptera, Odonata, Trichoptera and Diptera) into adjacent terrestrial ecosystems. The transfer of raw biomass from water to land was 7.385 g/m² per year, in dry weight - 2.216 g/m² per year; transfer of the main nutrients - 1.21 g/m² per year - carbon, 0.25 g/m² per year - nitrogen, and 0.03 g/m² per year - phosphorus; PUFA transfer - 24.16 kg/km² per year.

Bacteria perform important and diverse functions in the ecosystems of large rivers. The abundance, biomass and spatial distribution of heterotrophic bacterioplankton and its size-morphological groups were studied in the middle and lower reaches of the Ob River in the areas impacted by cities. The river water was characterized by a high content of suspended particles (on average (2.22 ± 0.21) × 10⁶ ml^-1), to which a significant part of bacteria was attached: on average, 41.5 % of their total number and 35.7 % of their biomass. The concentration of suspended particles and water conductivity were found to be among the main factors affecting the abundance and structure of bacterioplankton. A significant increase in bacterial abundance, mainly due to small free-living bacteria, was recorded below the mouth of the largest tributary, the Irtysh River, and the city of Khanty-Mansiysk. On this section of the Ob River, the average values of bacterioplankton abundance and biomass were (6.87 ± 4.99) × 10⁶ cells/mL and 142 ± 13 mg C/m³, respectively, which were 1.6-1.7 times higher than in the other sections. The spatial distribution of heterotrophic bacterioplankton in the Ob River is mainly determined by the dynamics of water masses and the influence of tributaries and cities.