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Formulation of the problem. Soils are a significant source of greenhouse gases (GHGs), the release of which into the atmosphere forms the global warming potential. Mathematical models describing greenhouse gas emissions make it possible to assess the impact of climate change on the GHG emissions on a regional scale, and study how land-use changes affect these emissions. The study is aimed at assessment of potential changes in CO2 and N2O emissions from soils at agroecosystems under the influence of temperature regime changes and increasing aridity in the context of global climate change. Materials and methods. Numerical experiments with a comprehensive model of GHG emissions from the soils at the winter wheat agroecosystem were performed by means of RCP4.5 climate change scenario. The study is based on the materials of agrometeorological observations at the hydrometeorological station of Bilovodsk (Eastern Ukraine) for the period of 1991-2020 and the climate change scenario RCP4.5 for the period of 2021-2050. Results. Classification of crop vegetation conditions allowed us to reduce the diversity of their regimes to certain weather types, characterizing the common conditions of crop formation in spring and summer, due to which the so-called ‘dry’ and ‘humid’ years were distinguished. The tendencies of change in air temperature and rainfall during vegetation of winter wheat in years different on humidity have been established. The increase in air temperature from the beginning of the growing season was gradual, while maintaining a stable correlation: a ten-day average long-term temperature was more than a temperature of the ‘dry’ year which was more than a temperature of the ‘humid’ year. The intensity of greenhouse gas emissions is defined by the type of humidification in the growing season. In the ‘dry’ years at the beginning of the vegetation season, CO2 emissions will make up 0.044-0.079 tons of С-CO2 ha-¹ per a ten-day period, which is higher than the average long-term values and almost twice as high as in the ‘humid’ years. In the spring at the beginning of the growing season, as a rule, the level of moisture content in the arable soil layer is quite high, which leads to the formation of anaerobic conditions. They, in turn, determine the level of N2O emissions. Increasing aridity reduces the level of N2O fluxes. For ‘dry’ years, at the expense of a fairly high level of spring moisture of the arable layer at the beginning of the growing season, the level of N2O emissions was quite high (0.061-0.089 kg of N-N2O ha-1 per a ten-day period). Subsequently its level decreased significantly. In general, total greenhouse gas emissions in terms of CO2 equivalent will decrease by 6.2% in ‘dry’ years and by 32.3% in ‘humid’ years. Conclusions. Based on numerical experiments with the model of greenhouse gas emissions from soils at the winter wheat agroecosystem, the general patterns of vegetation-related variation of CO2 and N2O emissions are identified. The main patterns feature consists in increasing CO2 emissions during spring-summer vegetation of winter wheat from the beginning of a growing season to the wax ripeness phase and in decreasing N2O emissions from the beginning of the winter wheat growing season until its ending. Their peculiarities are defined by the years’ different humid conditions. [ABSTRACT FROM AUTHOR]

Problem formulation. One of the main factors affecting climate change is the greenhouse effect conditioned by adding greenhouse gases to the atmosphere, among which CO2, CH4 and N2O are the most dangerous heat-trapping gases. In addition to anthropogenic activities, the source of greenhouse gases is emissions from natural ecosystems and agroecosystems. Carbon dioxide (CO2) accounts for the largest share of greenhouse gas emissions, nitrous oxide (N2O) also has large global warming potential, being nearly 300 times higher than CO2 on a weight basis. The purpose of the study is to create the integrated model of greenhouse gas emissions from soils in the agroecosystems on the basis of studies concerning modelling carbon dioxide emissions from mineral soils, quantitatively describing nitrous oxide emissions and modelling agroecosystem productivity. Methods. Mathematical modelling of environmental processes, the synthesis of quantitative approaches to their description. Results. The results of modelling greenhouse gas emissions from soils in agro-ecosystems during 2017- 2019 obtained by means of the integrated model developed showed that there is an interseasonal and interannual variability of CO2 and N2O fluxes. The higher CO2 flow rate was observed in 2017, in 2018 the lower CO2 emission intensity was discovered and in 2019 the CO2 flow rate was even lower. The emission of greenhouse gases varies depending on soil temperature, moisture and humus level of the soil. The equally low level of CO2 fluxes was observed at sufficiently low (from 1 to 6°C) soil temperatures. It was 0.072 - 0.401 g C-CO2/m² /day. The highest level of CO2 emission was observed in 2017 with a combination of high soil temperature (24-27°C) and sufficient soil moisture, and varies between 1,058 to 1,307 g С- CO2/m² /day. It was revealed that the most intense emission of N2O was observed during periods of high soil moisture when anaerobic conditions were established in the soil. The denitrification process was particularly intense in the spring of 2019, when the seasonal precipitation sum was 226 mm, and water-filled pore space (WFPS) reached more than 0.8 relative units. The average emission level of N2O was 15.592 g N-N2O/m² /day over this period, and the total N2O emission was the highest (1.134 kg of N-N2O/ha). The N2O emission intensity varied depending on the meteorological seasons. In the spring of 2017 and spring of 2018, the total N2O emission was 0.153-0.173 kg N-N2O/ha. The N2O emissions reached to 0.202- 0.503 kg N-N2O/ha in the summer season and 0.192-0.660 kg N-N2O/ha in the autumn. The highest emission levels were observed in the spring seasons (2018 and 2019) and in the autumn months (2017 and 2018), an increase in soil moisture worsened soil aeration, which led to an intensive denitrification process. In total, for the three meteorological seasons the highest emission was in 2019 (1.567 kg N- N2O/ha). The emission level was lower in 2018 (1.323 kg N-N2O/ha) and even lower in 2017 (0.569 kg N-N2O/ha). Conclusions. Based on the synthesis of approaches to modelling CO2, N2O emissions and agroecosystem productivity, an integrated model of greenhouse gas emissions from soils in agro-ecosystems has been developed (plant-agrosoil-GHG-model). The interseasonal and interannual variability of CO2 and N2O fluxes and their dependence on weather conditions and humus level of the soil have been obtained. [ABSTRACT FROM AUTHOR]

The influence of different humidification types towards appearance of forest vegetation conditions on spatial organization of birds in the wood stands is analyzed. Population density, coefficient of occurrence, and informative connection with six types of soil humidification are given for 53 bird species. The informative estimation of every humidification type is determined for every bird species. Thereby it is definitely a contribution of every gradation of edaphic factor to the structural genesis of dendrophilous bird communities. The strongest informative connection between humidity gradients and the avifauna structure of the wood stands is available in dry edaphotopes for margin representatives and fresh one for typical forest species. These two humidification types play a start function in the structural genesis of some blocks of dendrophilous bird communities per se. It is determined that change of bird species of forest-steppe faunogenetic complex by species from Nemoral complex undergoes in most cases on the border of the gradient between fresh and humid edaphotopes. For 53 species of birds from dendrophilous complex is was revealed that the importance of different levels of soil moisture has a different impact in shaping of the modern structure dendrophilous avifauna. Dry and especially drily edaphotopes determine the spatial structure of the species that are of forest-steppe origin and belong to the representatives of the optional component of dendrophilous bird communities. Wet edafotopes are involved in the formation of the spatial structure of species of predominantly immoral origin and relate to the obligate component of representatives of dendrophilous bitd comminities. Gradient wetting of edaphotopes on the verge of 'linked'/'fresh' is restructuring for the bird communities. It takes an optional replacement red communists feature to obligate. Stands rather dry and fresh items currently being the most active formation of the spatial structure of bird communities. In relation to the stands for dryish soil compaction observed populations of species that nest there. The fort stands on fresh soil tend to be the emergence of new species for nesting communities. Despite the small area and the uneven spatial arrangement of belts that are caused the effect of irrigation, there are some places of nesting of small belts for species that occur there only because of the increased level of humidity and the presence of open temporary ponds used by waterbirds. These belts have a 'hunchback' profile, caused by the constant flooding, and as a result - a tall and dense stands in the center of the forest belt. Formation of watering places is a separate factor that attracts birds in plantations. This phenomenon is described in detail in the literature. Significant structural adjustment of reserve stands caused by the age and condition of vegetation diversity management techniques, moreover the "island" effect becomes characteristic is fewer birds - like dendrophilous. Under present conditions, it does not describe the dendrophilous features for the bird communities in general. Only a few species possess the most biocenotical selectively retain the characteristics inherent to the "island" type populations. The biosphere reserve "Askania Nova" represents the diversity loam with varying degrees of moisture and salinity. The most common are dark chestnut soils in the north of the reserve bordering the southern black soils. Most belts representing tree plantation reserve, located in dark chestnut soils with low humus content in loess loam. Also, the composition of the physical and chemical properties of soil contributes to some zoogenic factors. In relation to the spatial distribution of birds in the reserve, one of the leading factors of the spectrum is the nature of hydration. Directly or through the woody vegetation it determines the nature of the spatial distribution of bird dendrophilous complexes. Relatively high diversity was registered due to the variety of types of moisturizing various irrigation methods for soils. Protected steppe area, which is an indigenous prairie biogeocoenoses and buffer zone of the reserve devoid of any irrigation. Dendroparks and the area of a typical land reserve is the only territory where we registered waterbirds in artificial plantations. This phenomenon is described in detail in the literature. Artificially created temporary pond (puddle) significantly enrich nesting avifauna in tree plantations. Internal cessation of irrigation, which contirubute to the shift of bird species from the category like "water" in fresh and significantly intensifies adjustment in quantitative and qualitative composition of the breeding avifauna of the reserve. Changes among other options moisturizing shades avifauna respond usually quantitative structure rearrangements of existing species. [ABSTRACT FROM AUTHOR]