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

Anthropogenic load іs a leading factor in the morphological variability of Chondrula tridens (Gastropoda, Enidae) in the northwestern Azov Sea region

Morphometric data are widely used in biology to assess intraspecific and inter-population variability and for bioindication and environmental condition assessment. The following hypotheses have been experimentally tested in the paper: 1) the vegetation type affects the change in the shell shape of Chondrula tridens martynovi Gural-Sverlova & Gural, 2010; 2) the change in the shell shape of this species is influenced by the biotope moisture regime; 3) the shell shape changes depending on the anthropogenic load level. The material in the form of empty, fully formed Ch. tridens shells was collected in 2019 in the north-western Azov region within the basin of the Molochna River. The collection points were located in settlements and outside them and differed in vegetation, moisture regime and level of anthropogenic load. The vegetation has been expertly attributed to two alternative types: herbaceous vegetation and tree plantations. By moisture level, the locations have been assessed as xerophytic and mesoxerophytic. The anthropogenic load levels have been assessed as low, medium and high. The study revealed that the morphological characteristics of Ch. tridens demonstrate a significant component of variability, which is due to the shell size. The shell size depends on the anthropogenic impact level. Under conditions of high anthropogenic impact, the shell size increases. Mollusks from locations with low and medium anthropogenic impact levels did not differ in shell size. After extraction of the size component, morphological properties develop three main trends of variability. The mouth apparatus development of mollusks does not depend on the vegetation type, but depends on the biotope moisture level and the anthropogenic transformation level. The mollusk shell elongation was observed to have the opposite dynamics of the height parameters in relation to the width and depended on the level of anthropogenic load. Rearrangement in the mouth apparatus depended on the biotope moisture level and the anthropogenic load level. There were distinguished four clusters, the quantitative morphological features of which allowed us to identify them as morphotypes. Each location was characterized by a combination of different morphotypes, according to which the sampling points may be classified. Morphotype 1 corresponds to biotopes with low level of anthropogenic load, morphotype 4 corresponded to biotopes with high anthropogenic load. Morphotypes 2 and 3 corresponded to moderate level of anthropogenic load. Vegetation type is not an important factor in determining the morphotypic diversity of populations. Under xerophytic conditions, morphotypes 2 and 3 are more common, and under mesoxerophytic conditions, morphotypes 1 and 4 are more common. The range of molluscs in different habitats needs to be expanded in the future to clarify climatic and other patterns

Antenna system of ultrawideband borehole radar based on loaded electric dipoles

The design of an ultrawideband borehole radar antenna system based on loaded electric dipoles is presented. The antennas are designed to operate in a dielectric medium in the frequency range of 0.25–1 GHz. The results of calculations and measurements of antenna characteristics are presented. The results of sounding the objects when placing antennas in a medium with a relative permittivity of 4 are presented as well

Temporal dynamic of the phylogenetic diversity of the bird community of agricultural lands in Ukrainian steppe drylands

This study discussed the importance of the phylogenetic components in the structure of bird communities of anthropogenically transformed ecosystems. The investigation was conducted in the landscapes of the south and south-east of Ukraine in the nesting seasons 1988–2018. The bird community in the agricultural landscape was found to be presented by 10 species. The number of species was closely correlated with its phylogenetic analogue – Faith’s index. Both indices were stationary over time, as they do not show a statistically significant time trend. The two axes were extracted as a result of the DPCOA procedure and the permutation test showed their statistical significance. The axis 1 was the most sensitive to the opposite dynamics of the abundance of Coturnix coturnix and Burhinus oedicnemus on the one hand and Alauda arvensis and Melanocorypha calandra on the other. The axis 2 is the most sensitive to the opposite dynamics of Corvus monedula and Melanocorypha calandra on the one hand and Coturnix coturnix and Motacilla flava on the other. Based on phylogenetic diversity, the years can be clustered with the extraction of four relatively homogeneous phylogenetic structures of bird communities. The indicator of the initial period of dynamics (1988–1992) was Burhinus oedicnemus. Sowing or mechanical weeding may be considered as a major factor of nest destruction of Burhinus oedicnemus. The decreasing of the abundance of the trophic recourses because of agricultural activity may have caused the monotonous negative trend over time of the Burhinus oedicnemus populations. The period 1993–2003 was a transitional one, for which there were no clear indicators, as a characteristic feature of this period was the processes of bird community restructuring. The period 2004–2013 was characterized by the loss of Burhinus oedicnemus from the community and a sharp increase in the abundance of Corvus monedula. These species are distinguished by their phylogenetic specificity and are located on the periphery relative to the phylogenetic core of the community. There was growing importance in the community of such species as Alauda arvensis, Anthus campestris, and Melanocorypha calandra between 2014 and 2018. Our results also confirm the assumption that phylogenetic overdispersion is an important requirement for the stability of the bird community in anthropogenically transformed landscapes

Thermal conductivity in a mixed state of a superconductor at low magnetic fields

We evaluate accurate low-field/low-temperature asymptotics of the thermal conductivity perpendicular to magnetic field for one-band and two-band s-wave superconductors using Keldysh-Usadel formalism. We show that heat transport in this regime is limited by tunneling of quasiparticles between adjacent vortices across a number of local points and therefore widely-used approximation of averaging over circular unit cell is not valid. In the single-band case, we obtain parameter-free analytical solution which provides theoretical lower limit for heat transport in the mixed state. In the two-band case, we show that heat transport is controlled by the ratio of gaps and diffusion constants in different bands. Presence of a weaker second band strongly enhances the thermal conductivity at low fieldsComment: 7 pages, 1 figure, discussion of the clean case and discussion of experiment adde

Intra population polymorphism of Caspian gull (Larus cachinnans) from the North-Western Coast of the Azov Sea (oological aspect)

Наведено результати дослідження у 1988–2013 рр. гніздових колоній мартина жовтоногого (Larus cachinnans Pallas, 1811) на островах Молочного лиману та Обитічної затоки Азовського моря (Південна Україна). Опис розмірних характеристик і забарвлення яєць жовтоногого мартина проводили за загальноприйнятими методиками. Було виміряно 1004 яйця мартина жовтоногого з п’яти колоній. За фоновим забарвленням шкаралупи яєць виділено 7 фенів, за типом малюнка на поверхні шкаралупи – чотири фени. У гніздових колоніях, які входять до складу різних гніздових поселень, спостерігаються відмінності розподілу типових і нетипових фенів забарвлення яєць і малюнка шкаралупи. За фоновим забарвленням і характером малюнка шкаралупи переважають яйця 3–4 фенотипів: сіро-зелені, з малюнком, який складається із плям середнього розміру (5–60%) та коричневі, з малюнком із великих плям (2–40%). Розміри яєць у різних поселеннях варіюють у межах 54,5–86,3 х 39,2–60,4 мм, об’єм яйця – 61,7–113,7 см3, індекс округлості – 63,6–85,3%. Лінійні розміри яєць залежать від чисельності гніздових колоній. Ооморфологічні ознаки можуть коливатися у визначених інтервалах. Вони характеризують самостійність окремих колоній, поселень і популяцій. На основі кластерного аналізу показників середніх лінійних розмірів яєць птахів декількох популяцій виділено три групи колоній: Дунайсько-Сиваська, Азово-Чорноморська та Кавказо-Каспійська. У межах Азово-Чорноморського регіону найбільшу схожість установлено між поселеннями Сиваша та Південного Криму, які, у свою чергу, подібні до колоній на Лебединих островах і Канівському заповіднику на Середньому Дніпрі. Азовські та Чорноморські поселення споріднені, відносно відокремлена Кавказо-Каспійська гілка. Встановлено вплив рівня гніздової чисельності на розмірні характеристики яєць: у період зростання чисельності (із 1970-х до початку 1990-х рр.) вони були максимальними, у період зменшення чисельності (2001–2005 рр.) – мінімальними. Ооморфологічні показники – зручний та об’єктивний метод дослідження стану популяцій птахів. Наведено результати дослідження у 1988–2013 рр. гніздових колоній мартина жовтоногого (Larus cachinnans Pallas, 1811) на островах Молочного лиману та Обитічної затоки Азовського моря (Південна Україна). Опис розмірних характеристик і забарвлення яєць жовтоногого мартина проводили за загальноприйнятими методиками. Було виміряно 1004 яйця мартина жовтоногого з п’яти колоній. За фоновим забарвленням шкаралупи яєць виділено 7 фенів, за типом малюнка на поверхні шкаралупи – чотири фени. У гніздових колоніях, які входять до складу різних гніздових поселень, спостерігаються відмінності розподілу типових і нетипових фенів забарвлення яєць і малюнка шкаралупи. За фоновим забарвленням і характером малюнка шкаралупи переважають яйця 3–4 фенотипів: сіро-зелені, з малюнком, який складається із плям середнього розміру (5–60%) та коричневі, з малюнком із великих плям (2–40%). Розміри яєць у різних поселеннях варіюють у межах 54,5–86,3 х 39,2–60,4 мм, об’єм яйця – 61,7–113,7 см3, індекс округлості – 63,6–85,3%. Лінійні розміри яєць залежать від чисельності гніздових колоній. Ооморфологічні ознаки можуть коливатися у визначених інтервалах. Вони характеризують самостійність окремих колоній, поселень і популяцій. На основі кластерного аналізу показників середніх лінійних розмірів яєць птахів декількох популяцій виділено три групи колоній: Дунайсько-Сиваська, Азово-Чорноморська та Кавказо-Каспійська. У межах Азово-Чорноморського регіону найбільшу схожість установлено між поселеннями Сиваша та Південного Криму, які, у свою чергу, подібні до колоній на Лебединих островах і Канівському заповіднику на Середньому Дніпрі. Азовські та Чорноморські поселення споріднені, відносно відокремлена Кавказо-Каспійська гілка. Встановлено вплив рівня гніздової чисельності на розмірні характеристики яєць: у період зростання чисельності (із 1970-х до початку 1990-х рр.) вони були максимальними, у період зменшення чисельності (2001–2005 рр.) – мінімальними. Ооморфологічні показники – зручний та об’єктивний метод дослідження стану популяцій птахів. This study presents the results of a long term study of nesting colonies of the Caspian gull (Larus cachinnans Pallas, 1811) on the islands of the Molochniy Liman and in Obitochnaya Bay (Azov Sea), in the South of Ukraine (Zaporizhia region), conducted between 1988 and 2013. A description of the size and coloring of eggs of Caspian gull was conducted by generally accepted methods. We measured 1000 eggs from 5 colonies of Caspian gulls. The background coloration of the eggs’ shells was classified into 7 types, the pattern of markings on the surface of the shells was classified into 4 types. In the nesting colonies, comprising different nesting settlements, the study tested differences in the distribution of typical and atypical coloring types and patterns on the surface of the shells. The background color and character of the shell marking patterns is dominated by eggs of phenotypes 3 and 4: gray-green, with a pattern of spots, of medium size (5–60%) and brown, with a pattern of large spots (2–40%). In different settlements the Caspian gull egg sizes vary in length and diameter of 54.5–86.3 x 39.2–60.4 mm, volume 61.7–113.7 cm3 and index of roundness 63.6–85.3%. The study revealed that the linear dimensions of eggs also depend on the number of birds in the nesting colonies. We found that morphological and dimensional characteristics of Caspian gull eggs can vary at certain intervals and characterize individual colonies, settlements and populations. Based on cluster analysis, conducted in terms of the average of the linear sizes of eggs of Caspian gull from several populations within the range of the species, the study identified three groups of colonies – Danube-Sivash, Azov-Black Sea and Caucasus-Caspian. In region of the Azov-Black Sea, the greatest similarity was shown between the settlements of Sivash and the South of Crimea, which in turn is similar to Lebiyazhyi Islands and Kaniv Nature Reserve (river Dnipro). A related link combined the Azov and Black Sea branches, while the Caucasus-Caspian group is relatively separate. As a result this study the influence of the number of nesting birds on the dimensional characteristics of the eggs was established; in the period of increase in the Caspian gull population from the 1970s to the early 1990s they had the highest scores, and in periods of decreasing population in 2001–2005, their values were lowest. Consequently, the use of oomorphological indicators turned out to be a fairly easy and objective method for studying the monitoring data for separate colonial bird species.

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 dy-namics 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 turno-ver 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. Keywords: ecosystem stability, temporal dynamic, estuary, beta-diversity, temperature, precipitation

Microscopic theory of thermal phase slips in clean narrow superconducting wires

We consider structure of a thermal phase-slip center for a simple microscopic model of a clean one-dimensional superconductors in which superconductivity occurs only within one conducting channel or several identical channels. Surprisingly, the Eilenberger equations describing the saddle-point configuration allow for exact analytical solution in the whole temperature and current range. This solution allows us to derive a closed expression for the free-energy barrier, which we use to compute its temperature and current dependences

Annual course of temperature and precipitation as proximal predictors of birds’ responses to climatic changes on the species and community level

The study was conducted in the landscapes of south-eastern Ukraine during the nesting seasons 1988–2018. Within the landscape system associated with the Molochny Estuary, the ten most important ecosystem types were investigated, including the following: agricultural land, vegetated strips, meadows, islands and spits, reedbeds, urban areas, salt marshes, steppe, cliffs, artificial forests. Bird species responded to temperature and precipitation gradients. The patterns of responses were presented using Huisman, Olff and Fresco expanded by the Jansen-Oksanen hierarchical models. The nature of species response in the gradient of temperature or precipitation conditions depends on the type of particular ecosystem and is not uniform for all populations inhabiting the different landscape types. The bird communities were revealed to demonstrate an abrupt dynamic over time. The continuous changes in community structure initiated by the external environmental factors are combined with modifications of internal biotic interactions, which may lead to abrupt reorganization of the community