Unstable Climatic Conditions Research Articles

A review of paleofloods in the middle-lower reaches of the Yangtze River during the Holocene: Processes, causes and effects

The understanding of the flooding processes in the entire basin of the middle-lower reaches of the Yangtze River (MLRYR) during the Holocene remains elusive. This is primarily attributed to the constraints posed by site-scale data characterized by limited spatiotemporal resolutions, compounded by conflicting results of the reconstructed Holocene paleoflood records in some of the previous studies. In this study, by synthesizing 114 paleoflood data with robust evidence of flood occurrence (including timing and location of flood occurrence), we comprehensively reconstructed the first continuous Holocene paleoflood record that cover the entire basin of the MLRYR. The results show that at the onset of the Holocene, flood frequency peaked notably in the middle reaches of the Yangtze River (MRYR), with no corresponding peak observed in the lower reaches of the Yangtze River (LRYR). However, in both the MRYR and LRYR, a significant flood frequency peak emerged around 8.0 ± 0.5 ka BP, and scarce flood occurrences appeared approximately 7.5–5.0 ka BP. This scarcity shifted abruptly to a surge in flood frequency from 5.0–4.0 ka BP. Following this, the MRYR witnessed three successive peaks in flood frequency, occurring at approximately 3.0 ka BP, 1.8 ka BP, and 1.0 ka BP, respectively. In contrast, flood events in the LRYR were infrequent during the 3.0–2.0 ka BP period, followed by a surge in frequency from 2.0 ka BP onwards. We further explored the driving mechanisms of paleofloods in the MLRYR and found that floods were more likely to occur during periods of weakened EASM, characterized by wet and unstable climate conditions in the MLRYR. Marine erosion may be also a key factor in the lack of geological evidence for palaeofloods during the early Holocene. Additionally, variations in the ISM and human activities during the late Holocene have significantly influenced the occurrence of floods in the MLRYR. By comparing the paleoflood frequency with the spatial distribution and number of archaeological sites in the MLRYR, respectively, we propose that the period of flood scarcity during the middle Holocene may have facilitated the development of rice agriculture and the prosperity of ancient settlements. In contrast, during flood-prone period, ancient societies adapted and coped with floods by migrating to higher terrain during the early Holocene and implementing simple hydraulic engineering techniques during the late Holocene.

COPING STRATEGIES ON CLIMATE VARIABILITY AMONG COWPEA FARMERS IN KWARA STATE, NIGERIA

<p><strong>Background.</strong> The unstable climatic conditions can no longer be predicted by farmers. The unpredictability intensity of temperature and pattern of rainfall in cowpea production has affected the farmers’ decision on production practices and general productivity. Therefore, farmers are beginning to improvise on management practices to avert the effects of climate change to remain relevant and profitable in the business of cowpea production. <strong>Objective.</strong> To examine the farmers’ coping strategies used against the effects of climate variability for cowpea production in Kwara State, Nigeria. <strong>Methodology.</strong> A multistage sampling technique was used to select 120 cowpea-based farmers. A structured survey questionnaire was used to collect primary data. Data were analysed with frequency, percentage, mean, and standard deviation while Pearson Product Moment Correlation was used to ascertain the relationship between socioeconomic characteristics and copying strategies used by farmers. <strong>Results.</strong> Majority (79.2%) of the respondents experienced high adverse effects of climate variability including abnormal rise in temperature (76.7%), irregular/unpredictable rainfall patterns (51.7%), and excessive rainfall (37.5%) on cowpea crop. The leading coping strategies used by farmers were use of fertilizer (x̄=2.73), herbicides (x̄=2.72), and planting early maturing variety (x̄=2.51). Farmers were mainly hindered by adequate irrigation facilities (x̄=1.72), inadequate access to extension services (x̄=1.66), and high cost of agrochemicals (x̄=1.60). Result education, cowpea farm size, years of experience in cowpea farming, membership in farmers group, and additional sources of information on cowpea production showed a positive significant relationship with the choice of coping strategies employed by cowpea farmers against the effects of climate change experienced at p<0.05 level. <strong>Implication.</strong> The study showed that abnormal rise in temperature and irregular rainfall patterns are affecting cowpea production and thus, some socioeconomic attributes significantly supported farmers’ choice of coping strategies employed against the effects of climate change and variability. <strong>Conclusion.</strong> The use of agrochemicals and cultivation of early maturing variety has played critical roles in coping with adverse effects of climate variability in cowpea production. </p>

Effect of solar radiation and full spectrum artificial sun light drying on the drying characteristics, ultra-structural and textural properties of white radish (Raphanus sativus L.)

Traditional sun drying has long been employed as a method for preserving radishes (Raphanus sativus L.) However, it suffers from various uncertainties, including weather-related factors such as rain and cloudy days, the pressing issue of climatic change can lead to an impact on the traditional drying process and texture of radish. In this research, the full spectrum artificial sunlight drying (FSASLD) has been implemented to simulate the traditional open sun drying of white radish slices which helps to prevent hygienic issues and unstable climatic conditions. Water activity (Aw) was measured and observed to decrease from 0.89 to 0.60 under both drying methods, indicating the removal of moisture from radish cells. Mathematical modelling and color kinetics models were studied with respect to drying time. Texture Profile Analysis (TPA) was employed to assess hardness, and results showed an increase in hardness following both SD (1018.24 g to 1327.67 g) and FSASLD (1018.24 g to 1731.04 g) salt treated radish slices. These findings suggest that FSASLD can serve as a viable alternative to the conventional drying method and contributes to agricultural innovation and the food industry, reducing drying time significantly from 270 min to 200 min and minimizing the impact of adverse weather conditions and interference from animals and microorganisms.

УСТОЙЧИВОСТЬ ЯБЛОНИ К ВЫСОКОТЕМПЕРАТУРНОМУ СТРЕССУ

Under unstable climatic conditions, the resistance of apple trees to high temperatures is an important varietal trait. The aim of the research is to identify heat resistance indicators of different apple varieties in a heat chamber for dry air treatment. The heat treatment of the varieties Antonovka Obyknovennaya, Lobo, Rozhdestvenskoe, Bolotovskoe, Kandil Orlovskiy, Imrus was carried out in a heat chamber at the temperature of +38°С and air humidity of 40% for 90 days. For the heat treatment, 2-year-old apple plants were used. Higher heat resistance was observed in the Lobo variety compared to the other varieties studied. The apple varieties were characterized by medium (Lobo, Rozhdestvenskoe) and high (Bolotovskoe, Imrus, Antonovka Obyknovennaya, Kandil Orlovskiy) water content, high water losses after a simulated heat shock, increased (Kandil Orlovskiy) and high (Bolotovskoe, Imrus, Antonovka Obyknovennaya, Lobo, Rozhdestvenskoe) wa- ter deficit, high degree of restoration of leaf water content. The proposed heat resistance coefficient was characterized by a strong degree of association with water loss (r = –0.97) and a moderate degree of association with water content restoration (r = 0.65). Apple plants had a high survival rate after thermotherapy, which was 92.3%.

A Comparative Study of PSO, GWO, and HOA Algorithms for Maximum Power Point Tracking in Partially Shaded Photovoltaic Systems

Abstract Solar energy harnessed through photovoltaic technology plays a crucial role in generating electrical energy. Maximising the power output of solar modules requires optimal solar radiation. However, challenges arise due to obstacles such as stationary objects, buildings, and sand-laden winds, resulting in multiple points of maximum power on the P–V curve. This problem requires the use of maximum power point tracking algorithms, especially in unstable climatic conditions and partial shading scenarios. In this study, we propose a comparative analysis of three MPPT methods: particle swarm optimisation (PSO), grey wolf optimisation (GWO) and Horse Herd Optimization Algorithm (HOA) under dynamic partial shading conditions. We evaluate the accuracy of these methods using Matlab / Simulink simulations. The results show that all three methods solve partial shading problems effectively and with high precision. Furthermore, the Horse Herd Optimization approach has superior tracking accuracy and faster convergence compared with the other proposed methods.

Current trends and prospects of apple breeding (<i>Malus</i> Mill) in Russia: review

In the Russian Federation, 506 varieties of apple trees are approved for use (10 included in 2023) with different periods of consumer ripeness of the fruit. The activities of breeding institutions have made it possible to improve the assortment of apple trees, while it is necessary to obtain new varieties of apple trees with a complex of adaptive traits and commercial and consumer qualities of fruits that ensure stable fruiting, productivity in unstable climatic conditions, as well as a long period of post-harvest storage of fruits; and, accordingly, determining the profitability of using these varieties in production plantings. In accordance with the increasing requirements for varieties, new breeding achievements must surpass previous analogues in a set of valuable breeding traits, which confirms the need to improve breeding programs. The key areas of apple tree selection are increasing winter hardiness, drought resistance, disease resistance, improving the biochemical composition and shelf life of the fruit, and columnar crown shape. Intensification of the selection process is necessary to reduce the time to obtain a new variety and its production development; in connection with this, marker-mediated selection is a promising direction for accelerating the selection process. The review article presents data on the work of scientific institutions where apple tree selection is carried out. The results of many years of work by leading research organizations of the Russian Federation in the field of apple breeding are covered. Data on scientific institutions, depending on their territorial location, are sorted by regions of admission of the State Register of Selection Achievements approved for use. The results of many years of work of leading research organizations, the main directions of apple breeding are covered, data on the use of modern methods for studying breeding material in research institutions are provided, and approaches to the early selection of economically valuable genotypes are presented. The analytical review is supplemented with information on ways to expand the genetic variability of hybrid offspring. The creation of varieties with a high level of adaptability, commercial and consumer characteristics of fruits will contribute to the further improvement of the apple tree assortment in the Russian Federation.

Salt and Water Stress Tolerance in Ipomoea purpurea and Ipomoea tricolor, Two Ornamentals with Invasive Potential

Invasive plants pose a significant threat to biodiversity, especially under the current unstable climatic conditions. This study aimed to test the salt and drought tolerance of two ornamental species of the genus Ipomoea during germination and vegetative growth. Germination tests were performed in the presence of increasing NaCl concentrations or iso-osmotic PEG concentrations—to mimic the osmotic stress caused by drought. Both species showed great invasive potential because of their high seed germination percentages and rapid germination under control (distilled water) and salt stress conditions, up to 200 mM NaCl. Germination and early seedling development were more affected in the presence of PEG. Subsequently, water stress (complete withholding of irrigation) and salt stress (watering with 100 mM and 200 mM NaCl) treatments were applied to young plants for three weeks, when all plants were harvested, to determine several morphological and biochemical parameters. Both species were sensitive to water deficit but relatively resistant to salt stress. Their salt stress responses were similar, based mainly on the inhibition of Na+ and the activation of K+ transport from roots to leaves and the uptake and accumulation of Ca2+; however, I. tricolor showed a slightly higher tolerance to salt stress than I. purpurea. Although I. tricolor has only been locally reported as invasive and is generally considered a ‘low-risk’ species, our results indicate that it may have an invasive potential even higher than I. purpurea, a recognised invasive weed, spread into areas with moderate salinity, affecting agricultural land or natural habitats of ecological interest.

Enhanced debris flow activities in the subtropical mountainous catchment of South China during early Marine Isotope Stage 3

Geomorphic processes and their responses to climatic change in subtropical mountainous catchments are not yet well understood. In this study, a unique sequence of alluvial sediments (>33 m thick) from the Nanxu karst valley, Guilin, South China, was investigated to characterize the nature of erosion–deposition processes in humid, subtropical catchments and decipher any climatic constraints on the earth surface dynamics and landscape evolution. Erosional outcrops show that the Nanxu valley fill sequence mainly comprises m-scale sheets of matrix-supported gravel (a debris flow facies), which, in the distal part of the valley, are intercalated with beds of fine-grained sediments (facies of horizontally interbedded sand and mud or massive mud). The fine-grained sediments were likely deposited in a subaqueous environment, which was probably formed when the karst sinkhole was contemporarily blocked by a large volume of debris flows. Optically stimulated luminescence (OSL) as well as radiocarbon dating constrained a chorology framework of ca. 62–42 ka for the valley fill sequence. Comparisons of the sedimentation phase with local and regional climate proxy records revealed that enhanced debris flow activities and sediment aggradation occurred under generally warm and wet but unstable climatic conditions during early Marine Isotope Stage 3. Under these climatic conditions, there was likely a subtropical landscape with high vegetation cover in the catchment at the time of sedimentation, as supported by our palynological data. Thus, it is suspected that enhanced debris flow activities were triggered by the recurrence of extreme monsoonal rainfall events. Since ∼ 42 ka, the stream-channel process dominated the valley, and the valley fill was deeply dissected, which might be related to changes in the overall intensity and internal variability of monsoonal rainfall over a period. These findings identify the role of high-intensity monsoonal precipitation in controlling geomorphological activities in humid, subtropical landscapes of South China.

An IoT-Based Model for Monitoring Plant Growth in Greenhouses

The unstable climatic conditions are promoting the adoption of smart agriculture. The introduction of IoT technology in the cultivation process allows for the monitoring and control of plant growth through automation. While the traditional greenhouse system is already an upgrade to the traditional cultivation system, it still has room for improvement with the integration of technology. The traditional greenhouse system requires close monitoring of growth rates through manual intervention and can be prone to various hazards. Incorrect interpretations of plant requirements can result in wrong interventions that may severely affect plant growth. It is imperative to have accurate data to maintain the health of plants throughout the cultivation process. IoT plays a predominant role in providing accurate data for constant monitoring of plant growth. The aim of this paper is to present a fully functional greenhouse automation model using microcontrollers, sensors, fans, pumps, and appropriate networking routing technology capable of providing instant data for proper monitoring of plant growth. The presented model includes safety features and can issue alerts in case security measures are breached. The system may even allow users to perform remote monitoring using a web application. Therefore, the proposed model will contribute to enhancing the horticultural industry by increasing output and reducing the need for human intervention.

Orbital‐ to millennial‐scale variation of the speleothem δ18O record during Marine Isotope Stages 5 to 3 on the southeast Chinese Loess Plateau and its climatic and environmental implications

ABSTRACTThe Chinese Loess Plateau (CLP) is located in northern China, a region climatically dominated by the East Asian monsoon. Speleothem records from this region are crucial to fully understand the variability of the East Asian summer monsoon (EASM) and reconcile the disparity seen between loess records and speleothem δ18O records for the EASM. Here, we present an absolutely dated stalagmite isotope record spanning most of Marine Isotope Stage (MIS) 5 to MIS 3 from Xiaotian Cave, southeast CLP. The Xiaotian speleothem δ18O record is dominated by precessional variations and punctuated by notable millennial‐scale oscillations; in particular, the δ18O values in MIS 5e, 5c and 5a were in the same range, consistent with other speleothem δ18O records from the EASM region within quoted errors, verifying the difference between speleothem δ18O and loess records (e.g. magnetic susceptibility) and the proposition that those two archives may record different aspects of the EASM changes. The similar values in MIS 5e, 5c and 5a observed from the speleothem δ18O records in EASM regions, incompatible with the relatively higher North Hemisphere Summer Insolation (NHSI) during MIS 5e, were probably caused by an equivalent or even increased contribution of 18O‐enriched moisture from the South China Sea and North Pacific, implying that an El Niño‐like state existed during MIS 5e. The Xiaotian δ18O values increased abruptly at ~121.7 thousand years (kyr) before the present (bp, present refers to ad 1950), consistent with the trend seen in previously reported Chinese speleothem δ18O records, indicating an abrupt regime shift in atmospheric circulations or hydroclimate conditions in the Asian monsoon systems. It cannot be definitely ruled out that an increase in sea ice extent in the northern North Atlantic, responding to a decrease of NHSI, reached a threshold to have led to abrupt changes in the Asian summer monsoon (ASM) through rapid shifts in the position of circulation of the westerlies and/or in the position of Intertropical Convergence Zone (ITCZ). Here, we hypothesized that sea surface cooling in the tropical Indian and Pacific Ocean caused by the decreased summer insolation reached a threshold that eventually resulted in an abrupt shift to more positive precipitation δ18O, either through weakened convection over the tropical ocean, or through abrupt shifts in moisture transport and cycling of tropical moisture sources for the ASM. The Xiaotian speleothem δ18O record also shows centennial‐scale variability with amplitude up to 3‰ within MIS 5e. These changes are similar to variations recorded by the speleothem δ18O record from Tianmen Cave on the south‐central Tibetan Plateau and Shangxiaofeng Cave in Shandong Province, northern China, suggesting a heightened sensitivity of precipitation δ18O to climate changes at the marginal zone of the ASM even during the warm and humid MIS 5e interglacial. Climatic oscillations during MIS 5e appear to be comparable to those typical of the Holocene, implying rather unstable climate conditions during the Last Interglacial.

Improvement of the grapevine gene pool on the basis of agrobiological and physio-biochemical assessment of new genotypes under the unstable moderate continental climate conditions of Southern Russia

Background. Development of table grape cultivars is currently aimed not only at higher vineyard productivity and grape quality but also at enhancing the adaptive potential of plants under the dynamic change in the climate conditions of Southern Russia. Increasing the share of modern Russian cultivars of table grapes will update and improve the assortment. The aim of this study was to evaluate new Russian hybrid grapevine forms according to their agrobiological, physiological and biochemical characteristics in the central agroecological zone of Krasnodar Territory.Materials and methods. Agrobiological characters were assessed using modern methods. Among physio-biochemical characters, the content of photosynthetic pigments was measured as well as the level of stress parameters under drought, such as the total water content in leaves and the content of malondialdehyde. Artificial drought was simulated to identify the most stress-resistant hybrid forms.Results. The highest values of fruitfulness coefficients k1 and k2 in the period of research were recorded for the Akello and Agat Dubovsky hybrid forms. Timoti and Agat Dubovsky had the maximum average yield for two years among the hybrid forms. The Gamlet, Kishmish Dubovsky, Agat Dubovsky and Timoti genotypes significantly exceeded the reference cultivar in the bunch weight. The Akello and Agat Dubovsky hybrids were identified for their physio-biochemical parameters: the highest content of chlorophyll in their leaves, high adaptive potential expressed in a low development level of secondary oxidative processes under stress, and the highest content of carotenoids.Conclusion. The obtained results evidenced that the Agat Dubovsky hybrid form could be identified as the most promising among the studied genotypes for cultivation in Southern Russia.

Diatom oxygen isotope records of Northern Eurasia as indicators of environmental, hydrological and climate changes in the regions

Abstract. The environmental, hydrological and climate dynamics were assessed in Northern Eurasia during the Holocene. The reconstructions are based on oxygen isotope composition of lacustrine diatom silica ( 18Odiatom) preserved in sediment cores from Ladoga, Bolshoye Shchuchye and Emanda lakes. Interpretation of the 18Odiatom data is supported by a comprehensive study of modern isotope hydrology and analysis of local and regional proxies. The Northern Eurasia 18Odiatom records are characterized by pronounced short term variations (1.5 5 ), pointing to the unstable climatic and hydrological conditions in the study regions. All records have clearly demonstrated a gradual depletion over the Holocene in their 18Odiatom values by ~3 4 , which follows the trend of decreasing summer insolation, as well as the temperature history of the Northern Hemisphere (NH), indicating a positive response of diatom oxygen isotope signal to large-scale climate changes.

Adaptation mechanisms of grape varieties in unstable climatic conditions of the autumn-winter period

Despite the increase in the average annual temperature observed in recent decades, the urgency of the problem of cold resistance of plants not only does not decrease, but also increases. The purpose of the work is to identify the mechanisms of adaptation of grape varieties of various origins to low temperatures in the autumn-winter period in terms of physiological and biochemical indicators, to identify varieties with a high adaptive potential for cultivation in the Anapo-Taman zone of the Krasnodar Region. Objects of the study: interspecific hybrids of grapes of various ecological and geographical origin: Crystal (control) - Euro-Amur-American; Krasnostop AZOS, Dostoyny - Euro-American; Vostorg - Amur-American; Zarif - Eastern European; Aligote - Western European origin. The implementation of the mechanisms of resistance of grapes to low temperatures was achieved by reducing the water content of tissues, increasing the proportion of bound water, the content of ascorbic acid, and changing the activity of peroxidase. Varieties Crystal, Krasnostop AZOS, Vostorg were distinguished by an increased ratio of bound and free water - 3.8-6.8; maximum accumulation of ascorbic acid (19.3-21.3 μg/g fresh weight), reduced peroxidase activity in comparison with other studied varieties. Varieties such as Crystal, Krasnostop AZOS, Vostorg proved to be more adaptive in comparison with other studied varieties and are recommended for the usage in the breeding process.

Breeding behaviour of ectotherms at high latitudes: the case of the natterjack toad Epidalea calamita at its northern range limit

Abstract We explored the breeding behaviour of a threatened amphibian, the natterjack toad, at its northern range limit in Estonia, to determine the extent to which reproduction is affected by harsh and unstable climatic conditions. Using photo identification of specimens, we found that in optimal weather conditions males formed three breeding cohorts, while in adverse conditions only a single cohort occurred and under extreme conditions reproduction was skipped entirely. During the extended breeding season, larger males participated in reproduction throughout the breeding period, while smaller males appeared in later cohorts. Breeding success was related to the calling effort of a male, where larger males had greater mating success than smaller ones. We found that the natterjack toad males exhibit significant plasticity in reproductive behaviour at the northern range limit, which, given the energetic cost of reproduction and the increased risk of predation, allows them to increase their fitness at high latitudes.

PECULIARITIES OF THE MEDICAL AND BIOLOGICAL EMERGENCY MANAGEMENT PROCESS IN A REGION WITH UNSTABLE NATURAL AND CLIMATE

The solution of the problem of determining the features of the process of emergency management of medical and biological nature in the region with unstable natural and climatic conditions in the conditions of constantly changing information load on the crisis management bodies is considered. Within the framework of the set task the modern tendencies of change of natural and climatic conditions in Ukraine and their influence on dynamics of distribution of medical and biological danger are analyzed. To consider the natural and climatic features of medical and biological emergency management on the example of the Cherkasy region as a region with unstable natural and climatic conditions. The obtained results allow, using innovative organizational and technical methods of prevention of emergencies of a similar nature, to further form a modern method of counteracting emergencies of medical and biological nature, supplementing these methods with an effective system of crisis management. It is determined that on the territory of Ukraine there is a sharp and heterogeneous change of weather and climatic conditions, which leads to potential negative consequences, as a man-made ecological nature, namely: thermal overload of a number of territories; increase of flooding areas; reduction of areas and violation of the species composition of green areas; increase of natural hydrometeorological phenomena; reduction of quantity and deterioration of drinking water quality; disruption of the normal functioning of energy systems and medical and biological nature, namely the increase in the number of infectious diseases and allergic manifestations, their modification and uncharacteristic growth and change of distribution areas; secondly, the nature of changes in weather and climatic characteristics in the Cherkasy region of Ukraine and its corresponding territorial location in relation to global climatic world processes defines the latter as a region with unstable weather and climatic conditions that territorially inhomogeneously affect the spread of medical and biological emergencies. Key words: emergency situation, mathematical model, medical and biological danger, anti-crisis management, unstable natural and climatic conditions.

Исследование вопроса возможности проектирования «зеленых» крыш в России на примере Рязанской области

Introduction. The era of high technologies and economy disrupts interaction between man and nature, worsening the state of the environment and living conditions on Earth. In Russia, the construction industry follows a classical development model and applies stereotypical patterns of urban design. Finding problem solving methods means identifcation of problem triggers that help to clearly understand and develop rational problem tackling mechanisms. Green roofs suggest an advanced approach to architecture and urbanization whereby green spaces take the place of new buildings. Supplementary dynamic space is not reduced to its decorative and environmental functions. Materials and methods. We applied such research methods as analysis, the system approach, synthesis, deduction, and comparative analysis. The initial review of the state of affairs in the Ryazan region was performed with regard for the theoretical nature of this study; correlation and regression analysis were employed to assess territories and spaces. Results. The history of green roof systems is analyzed in the article. Systematization of the effective regulatory and technical framework enabled the co-authors to assess the widespread applicability of the green roof technology in Russia. Special attention is paid to the issues that are not covered by effective domestic regulations. The research work has shown that the frst edition of GOST (All-Russian State Standard) 58875 is an attempt to consolidate previously issued manuals and recommendations. There is no information available about the seasonal efciency of green roof solutions in different Russian regions. A number of issues remain unresolved. The “green roof” policy has not been developed. Conclusions. Russia is not ready for large-scale construction of green roofs. Further research into green construction should be carried out with regard for unstable climatic conditions in different regions of the country to confrm the feasibility of green roofing at the legislative level.

Large-scale genetic structure and diversity of Arctic rainbow smelt Osmerus dentex Steindachner et Kner, 1870 throughout its distributional range based on microsatellites

Arctic rainbow smelt Osmerus dentex is one of the most abundant fish species widely distributed in the NW Pacific and Arctic seas. Studying this species can contribute to understanding the microevolutionary processes of the Arctic fauna in unstable climatic conditions and new habitats. However, little is known about the genetic structure and the mechanisms underlying its population dynamics. Ten microsatellite loci were used to genotype 822 individuals in 20 locations throughout a large part of the species’ range in the Sea of Japan, Sea of Okhotsk, Bering, Kara, and White seas (across more than 11,000 km). O. dentex displayed substantial levels of genetic differentiation (overall FST = 0.067, RST = 0.091) and STRUCTURE identified eight distinct clusters. The significant regional variation was demonstrated in both genetic diversity and population structure, most notably between Arctic and Pacific basins. On a regional scale, contrasting patterns were revealed with limited gene flow between populations of the Arctic region (FST = 0.117) and high gene flow between the Bering Sea (FST = 0.017) or Sea of Okhotsk (FST = 0.031), which were probably associated with differences in larval distribution from the spawning grounds due to different oceanographic conditions of the studied areas. These results demonstrate the effect of local contemporary forces in shaping different patterns of genetic connectivity and diversity within O. dentex.

Community dissimilarity of angiosperm trees reveals deep‐time diversification across tropical and temperate forests

AbstractQuestionTo better understand the influence of deep‐time diversification on extant plant communities, we assessed how community dissimilarity increases with spatial and climatic distances at multiple taxonomic ranks (species, genus, family, and order) in angiosperm trees. We tested the prediction that the dissimilarity–distance relationship should change across taxonomic ranks depending on the deep‐time diversification in different biogeographical regions reflecting geohistories and geographical settings.LocationGlobal.MethodsUsing a data set of plot‐based surveys across the globe (861 plots), we compiled a community composition matrix comprising 21,455 species, 2,741 genera, 240 families, and 57 orders. We then calculated Sørensen's pairwise dissimilarity (βsor), and its turnover (βsim) and nestedness (βsne) components, among plots within seven biogeographical regions. Finally, we modeled the relationships between the biotic dissimilarities and the spatial/climatic distances at each taxonomic rank, and compared them among regions.Resultsβsor and βsim increased with increasing spatial and climatic distance in all biogeographical regions: βsim was dominant in all biogeographical regions in general, while βsne showed relatively high contributions to total dissimilarity in the temperate regions with historically unstable climatic conditions. The βsim‐distance curve was more saturated at smaller spatial scales in the tropics than in the temperate regions. In general, the curves became flatter at higher taxonomic ranks (order or family), with the exception of Africa, North America, and Australia, pointing to region‐specific geographical constraints.ConclusionsCompositional dissimilarity was generally shaped through the abrupt turnover of species along spatial/climatic gradients. The relatively high importance of the nestedness component in the temperate regions suggests that historical dispersal filters related to extinction/colonization may play important roles. Region‐specific changes in the turnover and nestedness components across taxonomic ranks suggest differential imprints of historical diversification over deep evolutionary time in shaping extant diversity patterns in each biogeographical region.

Developing donors of ultra-early maturity in barley

Background. The length of the growing season is a limiting factor in many regions with unstable climatic conditions. The development of ultra-early barley donors makes it possible to accelerate the breeding process aimed at producing commercial cultivars adapted to cultivation area requirements.Materials and methods. The donors Kibel, Kibel uluchshenny, Kibtsel and Kibkor were obtained through individual selection of barley forms combining earliness and productivity from the hybrid combination Belogorsky × k-15881. The experiments were carried out according to the approved guidelines. Yield components were used to calculate the index of productivity for the donors versus the reference cv. ‘Belogorsky’.Results and conclusions. Earliness is controlled in the donors by three recessive genes. The donors’ period from emergence to heading was 7–9 days shorter than that of the reference cv. ‘Belogorsky’, with a low norm of reaction, which attested to their high adaptability. The resulting barley forms were highly resistant to lodging. The donor Kibel uluchshenny in all spike yield components did not differ from the reference. The other donors were close to the reference in spike length and 1000 seed weight. The example of Kibel uluchshenny was used to demonstrate the possibility of producing barley forms combining high earliness and good productivity. The developed donors may prove useful in the breeding for earliness in the areas where the length of the growing season is a limiting factor.

ИЗОТОПНЫЙ СОСТАВ КИСЛОРОДА И ВОДОРОДА ПОВТОРНО-ЖИЛЬНЫХ ЛЬДОВ ЦЕНТРАЛЬНОГО ЯМАЛА

New data on the distribution of the isotopes δ18О and δD of ice wedges in Central Yamal are presented. In the summer of 2019, the massive wedge ice was studied in the thermal circus of the third marine terrace. On the surface of the terrace, polygonal-vein relief is common with a polygon size of about 10–20 m. The largest ice wedge № 1 in the upper part was 1.5 m wide, and its visible depth in the outcrop amounted to 2.3 m. Perpendicular to this wedge, another one № 2 was opened with a width of 60 cm, and 20 m from them the wedge № 3 was opened along the strike. At the level of the head of the wedge № 1, radiocarbon AMS dating was performed based on a sample of host deposits, which showed that the ice in the upper part was about 13 thousand years old (the ice age was of 13.6 cal. BP). According to the isotopic characteristics (average values of δ18О = −24.8, and δD = −187.6 ‰), the ice corresponds to the Yamal ice-wedge ice, which was formed during the MIS‑2 isotopic stage (the end of the Late Pleistocene). The isotopic composition of oxygen indicates temperatures of the cold period of the vein formation from −22.8 to −26.8 °C (on average 7 °C colder than the present-day) and the January temperatures from −34.2 to −40.2 °C (on average 10 °C colder than the present-day). For some ice samples (11 out of 43), high values of deuterium excesses (dexc = 12÷17 ‰) were observed, which is unusual for this type of ice. A few examples of high dexc values of ice wedges are mentioned in the literature for sections of Seyakha yedoma, Cape Sabler and Bolshoi Lyakhovsky Island, and note that for the ice dated to the Late Pleistocene. The deuterium excess values may reflect the unstable climatic conditions of the Late Pleistocene associated with changes in the vapor source and the trajectories of the air masses over the continent.