The atmosphere as a lens

The advent of manned satellites has made it possible for man to observe Earth from great distances. Many new phenomena have been discovered in the atmosphere. These are evidently caused by reflection, scattering or refraction of light on crystals and drops of water. It is possible to see small objects on the surface of Earth because of these anomalies

Two-proton radioactivity and three-body decay. IV. Connection to quasiclassical formulation

We derive quasiclassical expressions for the three-body decay width and define the ``preexponential'' coefficients for them. The derivation is based on the integral formulae for the three-body width obtained in the semianalytical approach with simplified three-body Hamiltonian [L.V. Grigorenko and M.V.\ Zhukov, arXiv:0704.0920v1]. The model is applied to the decays of the first excited $3/2^{-}$ state of $^{17}$Ne and $3/2^{-}$ ground state of $^{45}$Fe. Various qualitative aspects of the model and relations with the other simplified approaches to the three-body decays are discussed.Comment: 9 Pages, 2 figure

Increased soil penetration resistance drives degrees of hemeroby in vegetation of urban parks

Urban parks provide a variety of ecosystem services, and a range of management practices promote their maximisation. The species diversity of plant communities is a factor in the maintenance of ecosystem services. The reconstruction of parks is one of the management practices, but the environmental impact of such activities is not clear. The reconstruction of parks affects vegetation and soil cover, and the interconnection of these components of the urban park ecosystem has not been studied before. The study revealed the features of variability of physical properties of soil and vegetation cover and identified their interconnection in the conditions of urban park reconstruction. The study was conducted in the recreational area of the Botanical Garden of Oles Honchar Dnipro National University (Ukraine). The park was studied in the area where reconstruction activities had previously been carried out. During the reconstruction process, walkways were restored, shrubs were removed, old or damaged trees were excavated, and tree crowns were trimmed. Young trees were planted in place of the removed old trees. Old outbuildings that significantly impaired the aesthetic impression of the park were also dismantled. The reconstruction involved transport and construction equipment. Samples were collected within transects, two of which were located in the reconstruction area, and two other transects were located in a similar area of the park where no reconstruction was carried out. The plant community was found to consist of 65 species. The mean level of alpha diversity was 11.5 species and beta diversity was 5.7. The alpha diversity was higher in the reconstructed park. The principal component analysis of the variability of soil properties extracted four principal components with eigenvalues greater than one. The principal components 1 and 3 reflect the variability of soil properties induced by the park's reconstruction, while the principal components 2 and 4 reflect variability that may be caused by other anthropogenic factors unrelated to the park's reconstruction, or may be due to natural variability of the soil cover. The principal component 1 indicates a uniform increase in the soil penetration resistance as a result of the application of technological processes during the reconstruction. This effect may be the result of the direct technological impact of the mechanisms employed and the large number of employees involved in the park's reconstruction. The condition of the crown space of the park plantation can explain the variation in soil penetration resistance. The increase in the height and projective cover of the grass vegetation is due to a decrease in the closure of the stand crowns, but the effect of such coordinated stand and grass dynamics on soil penetration resistance is observed only at a depth of 25–55 cm. This effect can be explained by the influence of the plant root system on the physical state of the soil. The root system of herbaceous plants is capable of loosening the soil and reducing its soil penetration resistance. The reconstruction of the park led to an increase in the hemeroby of the plant community. The criterion for the success of the reconstruction may be an increase in the attractiveness of the park for visitors without the risk of increasing hemeroby. The trend of increasing hemeroby clearly coincides with the direction of transformation of soil conditions, which are indicated by the principal component 1. The increase in the soil penetration resistance is a driver of the growth of vegetation cover hemeroby. The physical environment of the soil cover acts as an important environmental filter that affects the structure of the vegetation cover and the species composition of plant species complexes

Time turnover of species in bird communities: the role of landscape diversity and climate change

The challenge of searching for patterns of species turnover dynamics in communities of living organisms is directly related to solving problems of stability and functioning of ecosystems. Avian communities are an essential structural and functional component of terrestrial and aquatic ecosystems which are highly diverse and play an important role in a wide range of ecosystem functions. The issue of changes in the dynamics of amphibiotic landscape complexes, where terrestrial and aquatic ecosystems conjugate, is practically not solved. In this connection, a study was carried out within a landscape system, which presents terrestrial and aquatic ecosystems that were in different degrees of anthropogenic transformation. The dynamics of bird communities was considered in the context of recent global climate change. The investigation was conducted in the landscapes of the south and south-east of Ukraine in the nesting seasons 1988–2018. Within the landscape system associated with the Molochny estuary, the ten most important types of ecosystems were distinguished, which included : agricultural lands, artificial forest belts, meadows, islands and spits, reed beds, urban areas, solonchaks, steppe, cliffs, artificial forests. The temporal turnover of the bird communities was decomposed into two parts: the first term (D1) related to the amount of change in community composition, and the second term (D2) being dependent only on the amount of change in community size sensu its abundance. The contribution ratio of the species and of the environment variable were calculated to identify drivers that influence the turnover measure. The average annual temperature and the sum of annual temperatures were considered as environment variables. The bird metacommunity of the studied landscape system was represented by 132 species from 86 genera, 42 families and 13 orders. During the research period the average annual temperature varied from 9.5 to 12.5 ˚C. and the temperature dynamics were subject to the linear trend. An oscillatory component was also present in the temperature dynamics. The annual rainfall ranged 220–761 mm. A coherent change in precipitation and temperature was observed in the period until 2011. After that, the temperature growth stabilized and the amount of precipitation began to fall sharply. The steppe bird community was represented by an extremely small number of species, but demonstrated the ability to maintain a stable structure for a long time. The main fluctuations of the community were quantitative changes in abundance, while the turnover of species was practically absent. Species of the community replace each other cyclically, but there were no targeted changes in community structure. Temperature and precipitation were the main drivers of the bird community in the steppe. The bird communities on salt marshes were characterized by a stable abundance, but a constant directed turnover of species. Reduced water levels and the disappearance of islands in the salt marshes increased the risk of threats from predators, which could lead to a decrease in the abundance of some species. The islands and spits were characterized by high species turnover with quasi-cyclical population dynamics. The main feature of the community dynamics was a decrease in the role of precipitation and an increase in the role of the time factor. The role of temperature remained stably low. The species richness of bird communities in agrarian lands was higher than in steppe communities. The turnover measure was significant because of the increased abundance of Alauda arvensis. Over time, the role of precipitation in the community dynamics has been decreasing and the role of time has been increasing. The value of temperature varied, but was at a stationary level. The turnover of species was compensated by an increase in the abundance of bird communities. The obtained results are in line with findings indicating that despite more stable land use intensities in recent years, climate change has not overtaken land use intensities as the main driver of bird population dynamics

The spatio-temporal trend of rapeseed yields in Ukraine as a marker of agro-economic factors influence

The paper demonstrates the applicability of several statistical methods to the analysis and interpretation of the average rapeseed yield data. It proves our hypothesis that the general trend of rapeseed yield variations in Ukraine during 1991–2017 occurred due to agro-economic and agro-technological factors, which are the determinants of the revealed general trend. The temporal trend of rapeseed yield in most administrative districts can be described by a fourthdegree polynomial, namely, its characteristic points enabled us to describe and interpret the dynamics of rapeseed yields. The absolute term of the polynomial shows the initial conditions of the process, and its mapping allows us to identify the areas with the most favorable soil-climatic conditions for the rapeseed cultivation. Indicators of the maximum rate of growth and decrease of yields are the markers of stability of agro-ecosystems to the external influences. Therefore, the mapping of the maximum rate of decline and increase of yields reveal areas in which yields respond rapidly (increasing / falling) to the changes in agro-economic and agro-technological conditions, as well as areas where yields are more stable and change gradually. Thus, the form of the yield trend is determined by the influence of agro-technological and agro-economic factors, whose contribution to the fluctuation in rapeseed yields varies from 53% to 90%

Application of geographically weighted principal components analysis based on soybean yield spatial variation for agro-ecological zoning of the territory

ArticleIn this study, the geographically weighted principal components analysis as an alternative method for agro-ecological characterization of the region was provided. The spatial and temporal distribution pattern of soybean yield was analyzed by using spatial statistics technology, which provided a good reference for agricultural development planning. The soybean yield was selected for the present study because it is a comprehensive indicator reflecting the production potential of the regional agroecosystems. The organized data set, which included the average per year yields of soybean in 10 regions (206 administrative districts) of Ukraine, was used for analysis. The regular temporal trend, specific for each district, was previously extracted from the time series data. The principal components analysis of the detrended data allowed to identify four principal components, which altogether can explain 58% of the soybean yield variation. The geographically weighted principal components analysis allowed to reveal that four spatially determined processes were influencing the yield of soybeans and had the oscillatory dynamics of different periodicity. It was hypothesized that the oscillating phenomena were of ecological nature. Geographically weighted principal component analysis revealed spatial units with similar oscillatory component of soybean yield variation. Our study confirmed the hypothesis that within the studied territory there are zones with the specific patterns of the temporal dynamics of soybean yield, which are uniform within each area but qualitatively different between zones. The territorial clusters within which the temporal dynamics of soybean yield is identical can be considered as agro-ecological zones for soybean cultivation

Diversity of diversity indices: Which diversity measure is better?

The article evaluates the dependence of the most common indices of species diversity on sample size and determines their ability to differentiate between different types of ecosystems, with a special emphasis on discriminating between natural and anthropogenic ecosystems. An approach to adjusting the indices to reduce their dependence on sample size was also proposed. The study was conducted in seven types of ecosystems: four were natural and three were anthropogenically transformed. Samples of soil animals were selected in 2011–2013 and 2021 using the same methods. A total of 20,518 soil animal specimens belonging to 202 species were collected in all study locations. The null alternative was generated by randomly selecting samples containing 2, 3, ..., 110 soil animals from the combined soil animal sample. For each gradation of sample size, 200 sample variants were formed. The density of soil macrofauna in natural ecosystems ranged from 3.6 ± 1.5 to 15.2 ± 6.9 specimens per sample, and in artificial ecosystems – from 13.2 ± 7.6 to 21.0 ± 11.9 specimens per sample. The number of species ranged from 22–80 species, and in artificial ecosystems it was 38–99 species. Indicators of species diversity correlated with each other. A high level of correlation was observed between indicators within groups of indices: indices of species richness and indices of heterogeneity and evenness. Fisher’s log-series alpha and the fundamental parameter of biodiversity were highly correlated with each other, as well as with the Margalef, species richness, and Chao’s species abundance indices. The log-normal distribution best describes the dominance patterns in terms of abundance in the natural ecosystems, and the Zipf-Mandelbrot distribution best describes the dominance patterns in terms of abundance in the artificial ecosystems. Diversity indices were ordered in the space of two dimensions, one explaining the variation between ecosystems and the other depending on sample size. The ordering of the traditional indices showed that there is a vacancy for the best index in the sense that such an index should best explain differences between ecosystems and differences between natural and artificial ecosystems. It should also be independent of sample size. The Simpson heterogeneity index and the Simpson evenness index were the best of the traditional indices, but they did not explain differences between ecosystems very well, especially when it came to distinguishing between natural and artificial ecosystems. The Margalef index, which is supposed to be independent of sample size, on the other hand, showed a very high level of dependence. Such a dependence was also found for the Menhinick index, though to a lesser extent. Obviously, size dependence negatively affects the differential ability of the indices. The corrected indices of species richness and the Shannon index are practically independent of sample size and have a greater ability to differentiate ecosystems by the level of diversity, with natural ecosystems characterized by consistently higher values of the corrected indices than artificial ecosystems. The dependence on the sample size makes indices from different ecosystems practically incomparable, which makes their use meaningless. Even minor differences in sample size can lead to significant deviations in the values of diversity indices. The application of the Michaelis-Menten model allowed us to suggest a method of correction of species richness indices and the Shannon index. After the correction, the indices are practically independent of the sample size, and their differential ability to characterize individual ecosystems and the level of anthropogenic transformation increases significantly

Electron-phonon relaxation and excited electron distribution in zinc oxide and anatase

We propose a first-principle method for evaluations of the time-dependent electron distribution function of excited electrons in the conduction band of semiconductors. The method takes into account the excitations of electrons by external source and the relaxation to the bottom of conduction band via electron-phonon coupling. The methods permits calculations of the non-equilibrium electron distribution function, the quasi-stationary distribution function with steady-in-time source of light, the time of setting of the quasi-stationary distribution and the time of energy loss via relaxation to the bottom of conduction band. The actual calculations have been performed for titanium dioxide in the anatase structure and zinc oxide in the wurtzite structure. We find that the quasi-stationary electron distribution function for ZnO is a fermi-like curve that rises linearly with increasing excitation energy whereas the analogous curve for anatase consists of a main peak and a shoulder. The calculations demonstrate that the relaxation of excited electrons and the setting of the quasi-stationary distribution occur within the time no more than 500 fsec for ZnO and 100 fsec for anatase. We also discuss the applicability of the effective phonon model with energy-independent electron-phonon transition probability. We find that the model only reproduces the trends in changing of the characteristic times whereas the precision of such calculations is not high. The rate of energy transfer to phonons at the quasi-stationary electron distribution also have been evaluated and the effect of this transfer on the photocatalyses has been discussed. We found that for ZnO this rate is about 5 times less than in anatase.Comment: 21 p., 9 figure

The importance of relief for explaining the diversity of the floodplain and terrace soil cover in the Dnipro River valley: The case of the protected area within the Dnipro-Orylskiy Nature Reserve

Floodplains are centers of species diversity, so floodplain habitats often contain protected areas. However, conservation strategies pay little attention to soils, on which the functional stability of both individual ecosystems and landscape chains as a whole depends. Soil morphology provides structural and functional information about floodplain ecosystems. The spatial and temporal heterogeneity of soil morphology is a cost-effective ecological indicator that can be easily integrated into rapid assessment protocols for floodplain and riverine ecosystem restoration projects. Therefore, the aim of our work was to consider the morphological features of soils of the Dnipro-Orylskiy Nature Reserve and assess the role of soil diversity as a factor of structural and functional sustainability of ecosystems of the protected area, as well as to identify the significance of geomorphological predictors for differentiation of soil types to create a soil map of the territory. The World Reference Base for Soil Resources reference soil groups were classified using geomorphological predictors. Soil types were able to explain 90% of the variation in elevation occupied by soils. Arenosols occupied a statistically significantly higher position in topography than other soil types. In turn, Eutric Arenosols occupied a higher position (68.91 ± 0.48 m) than Eutric Lamellic Arenosols (63.32 ± 0.54 m). Other soils occupied positions in the topography that were not statistically significantly different in height. Soil types were able to explain 38% of the variation in elevation that the soils occupied. The highest Topography Wetness Index values were found for Fluvisols (12.73 ± 0.23) and Solonetz (13.06 ± 0.28 m). Differences between these soils were not statistically significant. Topography Wetness Index was slightly lower for Cambisols (11.80 ± 0.21) and Eutric Lamellic Arenosols (12.21 ± 0.28), which also did not differ on this measure. The lowest Topography Wetness Index value was found for Gleysols (11.15 ± 0.17) and Eutric Arenosols (10.95 ± 0.24), which did not differ from each other on this index. Eutric Arenosols and Eutric Lamellic Arenosols are formed at great depths of the water table (7.89 ± 0.50 and 2.62 ± 0.46 m, respectively). Gleysol and Solonetz form at close groundwater level to the surface (0.28 ± 0.27 and 0.21 ± 0.46 m, respectively) compared to Fluvisol and Cambisol (0.46 ± 0.38 and 0.41 ± 0.35 m, respectively). Elevation was the most informatively valuable predictor, but Topography Wetness Index and Vertical Distance to Channel Network significantly improved discrimination. Arenosols were very different from other soils which occupy an automorphic position. Cambisols occupied a transitional position. Other soils occupied hydromorphic positions. Fluvisols and Solonetz occupied wetter positions, while Gleysol occupied less wet positions. Fluvisols and Solonetz differed in the groundwater table. Solonetz predominantly occurred at close groundwater levels. The classification matrix confirmed the possibility of using geomorphological predictors to build a model of spatial variation of soils in the study area. The spatial model demonstrates the organization of the soil cover of the reserve. Calculations showed that Cambiosols occupy 20.7% of the area, Eutric Arenosols occupy 16.0%, Eutric Lamellic Arenosols occupy 17.9%, Fluvisols occupy 15.2%, Gleysols occupy 28.7%, and Solonetz occupy 1.5%