Precipitation In May Research Articles

Yield and grain quality of spring durum wheat in the conditions of the Orenburg Cis-Urals

The article contains an analysis of the prevalence of spring durum wheat crops in the world and in the Orenburg region, and yields over a long period. There is a tendency to decrease the productivity of this crop over the studied period, primarily due to the increasing aridity of the growing season. The results of a correlation and regression analysis of the dependence of its yield on the main weather indicators are presented, while identifying their optimal values for the formation of highly productive crops of this crop. Analyzing the obtained dependencies, attention is focused on the intensity of the growing conditions of spring durum wheat in recent years in the arid zone, which do not allow realizing the potential of this crop. The calculated coefficients of the relationship between the yield of this crop and weather factors show reliable dependences on the temperature regime of May, July, the amount of precipitation in May and the relative humidity of the entire growing season. The results of the mathematical dependence of durum wheat grain quality indicators on the weather characteristics of the growing season are presented. At the same time, the optimal air temperature values in May were 13.4 °C, in June 15.0 °C, in July 23.3 °C, according to the amount of precipitation, the optimal amount for the months of vegetation was 30 mm in May and June and 36 mm in July. The above–mentioned optimal values of weather factors in May corresponded to the theoretical yield of durum wheat up to 30.0 c from 1 ha, the optimal values in June - 22.6 c from 1 ha and the optimal values in July – 18.9 c from 1 ha. Correlation coefficients and actual data on grain quality indicators allow us to note their significant variability from the conditions of the growing season and varietal specificity. A high correlation (r = 0,827-0,926) was established for the studied grain quality indicators with average relative humidity and with an average daily humidity deficit. The average relationship (r = 0.635-0.745) was obtained for the average air temperature, maximum air temperature and average daily humidity deficit. Grain quality is subject to variability from the conditions of the growing season: in harvest years, there is an increase in the vitreous content of grain to 92-93%, and in years with an increase in the temperature regime of the air, there is an improvement in the quality of gluten to the level of class II.

Effect of climate change on Clinopodium polycephalum (Vaniot) C. Y. Wu & S. J. Hsuan distribution adopting temporal data, ArcGIS, and the MaxEnt model.

Clinopodium polycephalum (Vaniot) C. Y. Wu & S. J. Hsuan, a vital plant in traditional Chinese medicine, has been used for its hemostatic properties since 1220 AD. Despite its recognized medicinal benefits including anti-inflammatory and cardiovascular applications and increasing market demands, research on this plant remains limited, particularly from the perspective of plant ecology. Due to global warming and the resultant climate change, studies on the distribution and conservation of C. polycephalum are of great importance, especially when a clear trend that its habitat shifts to the north was observed. To predict the potential distribution of C. polycephalum under distinct climate situations, the MaxEnt model was used along with the ArcGIS software. As a result, an AUC value of 0.931 was achieved, indicating high predictive accuracy of the model. By analyzing 135 occurrence points and their corresponding bioclimatic factors (including precipitation), soil data, and other environmental variables (49 in total), 16 key factors including pH value and basic saturation were selected for downstream analysis. It was found that solar radiation in May, precipitation in May and April, and the lowest temperature in the coldest month are important factors influencing the growth and distribution of C. polycephalum. Compared to the current climate scenario, the future suitable habitat for C. polycephalum is expected to shift northwest, and under the SSP245-2061-2080 climate scenario, its highly suitable habitat area is projected to increase by 886,000 km2. These findings provide crucial insights into the environmental drivers of C. polycephalum distribution and aid in its preservation and sustainable use in traditional medicine. Based on the findings of this study, future research should focus on factors such as solar radiation in May and the lowest temperature in the coldest month within the suitable habitat to ensure its effective conservation.

Increased Extreme Precipitation in May over Southwestern Xinjiang in Relation to Eurasian Snow Cover in Recent Years

Abstract In this study, the interdecadal variations of extreme precipitation in May over southwestern Xinjiang (SWX) and related mechanisms were investigated. The extreme precipitation in May over SWX exhibited a decadal shift in the 1990s (negative phase during 1970–86 and positive phase during 2003–18). The decadal shift corresponded to strengthened moist airflow from the Indian Ocean and an anomalous cyclone over SWX during 2003–18. It is found that the interdecadal change of the wave trains in Eurasia might account for the differences in atmospheric circulation between the above two periods. Further analyses reveal that spring snow cover over Eurasia is closely linked to extreme precipitation over SWX during 2003–18. Increased snow cover in western Europe (WE) from February to March is accompanied by more snowmelt. This resulted in less local snow cover and lower albedo, leading to warm temperatures over WE in May. The changes in temperatures increase the local 1000–500-hPa thickness over WE. These factors provide favorable conditions for the enhancement of the Eurasian wave trains, which significantly influence extreme precipitation over SWX. On the other hand, corresponding to decreased albedo caused by the reduction of snow cover in northern Eurasia (NE) in May, anomalous surface warming occurs over NE. The anomalous warming results in positive geopotential height anomalies that intensify the meridional geopotential height gradient over Eurasia and cause an acceleration of the westerly jet in May. Anomalous upper-level divergence in SWX induced by the enhanced westerly jet provides a favorable dynamical condition for increased extreme precipitation.

Hydrological dynamics of snowmelt induced streamflow in a high mountain catchment of the Pyrenees under contrasting snow accumulation and duration years

AbstractSnowmelt drives a large portion of streamflow in many mountain areas of the world. However, the water paths from snowmelt to the arrival of the water in the streams are still largely unknown. This work analyzes for first time the influence of snowmelt on spring streamflow with different snow accumulation and duration, in an alpine catchment of the central Spanish Pyrenees. This study presents the water balance of the main melting months (May and June). Piezometric values, water temperature, electrical conductivity and isotope data (δ18O) allow a better understanding of the hydrological functioning of the basin during these months. Results of the water balance calculations showed that snow represented on average 73% of the water available for streamflow in May and June while precipitation during these months accounted for only 27%. However, rainfall during the melting period was important to determine the shape of the spring hydrographs. On average, 78% of the sum of both the snow water equivalent (SWE) accumulated at the beginning of May and the precipitation in May and June converted into runoff during the May–June melting period. The average evaporation‐sublimation during the 2 months corresponded to 8.4% of the accumulated SWE and rainfall, so that only a small part of the water input was ultimately available for soil and groundwater storage. When snow cover disappeared from the catchment, soil water storage and streamflow showed a sharp decline. Consequently, streamflow electrical conductivity, temperature and δ18O showed a marked tipping point towards higher values. The fast hydrological response of the catchment to snow and meteorological fluctuations, as well as the marked diel fluctuations of streamflow δ18O during the melting period, strongly suggests short meltwater transit times. As a consequence of this hydrological behaviour, independently of the amount of snow accumulated and of melting date, summer streamflow remained always low, with only small runoff peaks driven by rainfall events.

Влияние метеорологических условий на рост культур ели с закрытой корневой системой

The assessment results of the five- and seven-year-old European spruce crops growth in the Gryazovetsky district of the Vologda region, created by one- and two-year-old seedlings with a root-balled tree system with improved hereditary properties, are presented. It is noted that in the studied seven year-old crops, the proportion of spruce in the plantation composition reaches four points, and in five-year-old — from two to four points. Natural renewal of hardwoods due to timely clearing is located mainly in the inter-row spacings and, by now, does not depress cultivated plants. All the surveyed sites are characterized by a tendency to increase the annual growth of terminal shoot, as well as a decrease in the level of its fluctuation with age. The correlation ratio (η = 0,85) indicates a high dependence of the growth of the axial shoot on the year of its formation. It is shown that meteorological factors influence the growth of spruce crops created by seedlings with a root-balled tree system in the phase of their individual growth. The greatest influence is the sum of the active temperatures of the growing season, precipitation, relative humidity in May and June and the average air temperature in the daytime. At the same time, the growth of axial shoots increases with an increase in the number of days with precipitation in May, but decreases with their increase in June. A significant positive dependence of the increase was noted on the relative humidity of the air in May, however, increased humidity in June leads to a decrease in the growth of spruce crops.

Analysis of Radial Growth Dynamics of Pinus Nigra Subsp. Pallasiana (Lamb.) Holmboe in Different Parts of the Slope Profile

The results of the research of radial growth of Pinus nigra trees growing in the foothill-forest-steppe zone (in Belogorosk district) with continental climate type of the Crimean Peninsula are presented. The research was con[1]ducted to evaluate the influence of the location of the growth site on the local slope on the total width of the annual ring. Geomorphologically, the sampling points were located along the profile of a gentle convex slope of eastern exposure. Wood samples were collected at sites within the lower, middle and watershed parts of the slope, as well as at the top of the Biyuk-Karasu River watershed. Generalised tree-ring chronologies were obtained for each part of the slope, the average age of the chronologies being 50 years. As a result of the research, a synchronism in growth dynamics of trees growing in the lower part of the slope and in the watershed was established; the radial growth of Pinus nigra trees in the middle parts of the slope reacts the earliest to the influence of environmental factors. The reaction lag of radial growth in the watershed part of the slope is about 11 years. Analysis of the constructed chronologies shows that over the past 50 years, the radial growth is comparable to the dynamics of meteorological parameters. The analysis of correlations of the obtained chronologies with the values of average monthly air temperatures and annual precipitation according to the data of the Simferopol meteorological station was carried out. For the lower and middle parts of the slope, as well as for the watershed, the amount of precipitation is more significant than air temperature. Correlations have been established between the radial growth index of the lower and middle parts of the slope, as well as watershed and the sum of precipitation in May, and the summer months of both the current and previous years. For Pinusnigra trees growing on the watershed parts of the slope, air temperatures of summer months of the current and previous year are more significant. The established close relationship can be used to reconstruct climatic conditions of Pinus nigra trees.

An analysis of yield dynamics in Peredovik sunflower variety in the conditions of the North Caucasus Region

The results of observations for 1971–2002 were used to analyze the long-term trends of yield and the duration of the growing season in the sunflower variety Peredovik. The regression analysis has shown that the growing season duration decreases with the increase in the sum of temperatures above 15 °C. The yield of sunflower was negatively associated with the sums of temperatures and the sums of precipitation in May–August, and positively with the precipitation in April. According to the regression analysis in differences, the main factor influencing the yield variability was the hydrothermal coefficient for the period with temperatures above 20 °C, the second factor was spring precipitation. The possible presence of a non-linear trend in yield dynamics that is not related to weather and climate conditions has been revealed. With the sustained tendency of the last 30 years towards an increase in temperatures and a decrease in precipitation in April, the growing season will keep shortening and the yield decreasing.

Species distribution model identifies influence of climatic constraints on severe defoliation at the leading edge of a native insect outbreak

Eastern North America is in the midst of a spruce budworm (Choristoneura fumiferana Clem., SBW) epidemic. SBW is one of the most important forest insects with regard to outbreak coverage and impacts to the forest industry in this region. Numerous bioclimatic, vegetation, and spatial–temporal variables can influence the distribution and outbreak patterns of phytophagous insects such as SBW. Published models have yet to agree on consensus drivers of SBW defoliation. Spatially-explicit, fine-scale predictive models are needed, however, to aid in our understanding of current and future SBW impacts. We used a species distribution model - MaxEnt to examine the relationships between the 1972–1981 SBW defoliation and 13 predictor variables for the island of Newfoundland, Canada the leading edge of the current SBW outbreak. The optimal model for predicting the probability of severe SBW defoliation included precipitation in May and June, precipitation in July and August, and maximum temperature in June and July. The probability of severe defoliation rapidly increased when precipitation ranged at 75.0 mm – 91.0 mm in May and June but showed a complex relationship with precipitation in July and August. Probability also increased with maximum temperature in June and July until temperature reached 18.0 °C. Defoliation probability decreased with increasing distance from major roads and river channels, suggesting possible corridor effects. Counter to research in other study areas, host tree species was not an important predictor of defoliation in our analysis. We then used this MaxEnt machine learning algorithm to predict the probability of severe defoliation for the forests of the entire island on a 2 km resolution raster. Areas with high probability (>0.80) were concentrated in the northeast part of the island where black spruce (Picea mariana (Mill.) BSP) dominates the forest landscape. The predicted severe defoliation area (probability 0.4–1.0) for black spruce was 1.4 times the area for balsam fir, which is the dominant canopy forming tree species on the island and preferred host species for SBW. The higher predicted probability of severe defoliation in black spruce stands relative to balsam fir stands may arise due to the unique combination of climatic conditions and geographical distributions of two species on the island. Species distribution models for irruptive insect impacts (i.e., defoliation) are relatively rare but may be an important tool in forecasting future insect damage.

Selecting High-Performing and Stable Pea Genotypes in Multi-Environmental Trial (MET): Applying AMMI, GGE-Biplot, and BLUP Procedures.

A large amount of data on various traits is accumulated over the course of a breeding program and can be used to optimize various aspects of the crop improvement pipeline. We leveraged data from advanced yield trials (AYT) of three classes of peas (green, yellow, and winter peas) collected over ten years (2012-2021) to analyze and test key aspects fundamental to pea breeding. Six balanced datasets were used to test the predictive success of the BLUP and AMMI family models. Predictive assessment using cross-validation indicated that BLUP offered better predictive accuracy as compared to any AMMI family model. However, BLUP may not always identify the best genotype that performs well across environments. AMMI and GGE, two statistical tools used to exploit GE, could fill this gap and aid in understanding how genotypes perform across environments. AMMI's yield by environmental IPCA1, WAASB by yield plot, and GGE biplot were shown to be useful in identifying genotypes for specific or broad adaptability. When compared to the most favorable environment, we observed a yield reduction of 80-87% in the most unfavorable environment. The seed yield variability across environments was caused in part by weather variability. Hotter conditions in June and July as well as low precipitation in May and June affected seed yield negatively. In conclusion, the findings of this study are useful to breeders in the variety selection process and growers in pea production.

Dendroclimatic response of Pinus tabuliformis Carr. along an altitudinal gradient in the warm temperate region of China.

Global climate change can affect the sensitivity of tree radial growth to climate factors, but the specific responses of tree radial growth to microclimate along the altitudinal gradient in the long term are still unclear. In this study, the tree-ring width chronologies of Pinus tabuliformis Carr. in Shanxi Province of China were studied at three altitude gradients (1200-1300m (low altitude), 1300-1400m (medium altitude) and 1400-1500m (high altitude)) during 1958-2017. The results showed that (1) the climate background could be divided into two periods based on the Mann-Kendall test analysis: 1958-1996 was a stable period (mean annual temperature (MAT)=10.25°C, mean annual precipitation (MAP)=614.39 mm), and 1997-2017 was a rapid change period (MAT=10.91°C, MAP=564.70 mm), indicating a warming and drying trend in the study region. (2) The radial growth of P. tabuliformis at different altitudes showed inconsistent variation patterns. The tree radial growth at low and medium altitudes (CV=27.01% for low altitude and CV=24.69% for medium altitude) showed larger variation amplitudes during the rapid change period than that in the stable period (CV=12.40% for low altitude and CV=18.42% for medium altitude). In contrast to the increasing trend, the tree radial growth rates at the high altitude showed a decreasing trend across years. (3) In the stable period, the radial growth of P. tabuliformis at the low altitude showed a significantly negative response to temperature and a positive response to precipitation in May and June. The tree radial growth at the medium altitude was positively related to precipitation in June and minimum temperature in February. The tree growth at the high altitude was mainly positively correlated with the temperature in May and August. In the rapid change period, the radial growth of P. tabuliformis at the low altitude was affected by more meteorological factors than that in the stable period. Medium-altitude trees were positively influenced by precipitation in June and minimum temperature in January, whereas high-altitude trees responded positively to wind speed in February. (4) Along altitudinal gradients, tree radial growth was more related to temperature than precipitation in the stable period. The tree radial growth at the high altitude during the rapid change period was only affected by wind speed in February, whereas the tree radial growth at low and medium altitudes was mainly affected by temperature to a similar extent during the two periods. The study indicated that tree growth-climate response models could help deeply understand the impact of climate change on tree growth adaptation and would be beneficial for developing sustainable management policies for forest ecosystems in the transition zone from warm-temperate to subtropical climates.

Flash floods and landslides in the city of Recife, Northeast Brazil after heavy rain on May 25–28, 2022: Causes, impacts, and disaster preparedness

From late May to early June 2022, 130 people died in catastrophic landslides and flash flood events triggered by exceptionally heavy rains in the states of Pernambuco, Alagoas, and Paraíba, along the coast of Northeast Brazil. Total rainfall in the city of Recife on May 25–30 was 551 mm, 140 mm higher than the average of the month of May. Rain was heaviest on May 25 and 28, with 100–200 mm and 151–250 mm, respectively. This coincided with easterly wave disturbances. May 28 saw the most rain, due to a significant cold front. Fourteen municipalities in the metropolitan region of Recife declared a state of emergency. According to the Civil Defense of Pernambuco state, the rain impacted 130,000 people there. Most of the heavy precipitation fell over areas with medium to very high geological vulnerability to landslides and extreme hydrological events. The loss of life and substantial economic impacts in Recife caused by the heavy precipitation of May 2022 and the disasters induced by it show that this city, like many others around the world, has limited capacity to cope with climate extremes. Urbanization has increased population density occupying hills and slopes of the city, contributing to the problem. To reduce the impact of such disasters, residents must be made aware of the risks of climate-related events, and they must be encouraged to heed alerts warning of natural disasters issued by state and federal institutions. Efficient monitoring of risk is also needed. Risk management will be viable only when everyone participates, which requires education and cultural change.

Радиальный рост сосны обыкновенной в условиях северной тайги

The research aims at assessing the influence of daytime and nighttime meteorological parameters (air temperature, dew point, relative air humidity, wind velocity and amount of precipitation) on the pine radial growth in the northern taiga subzone in blueberry, lingonberry and bush-sphagnum forest types. The study was carried out in the Arkhangelsk region near the Pinega settlement (northern taiga subzone). Sample plots were laid out in areas with different forest types specific for this territory. A total of 63 core samples were taken from 7 of the most representative sites. Meteorological parameters for 2008–2015 were collected by a digital weather station WMR918 H (Huger GmbH, Germany) located in the research area and operating in the monitoring mode. In blueberry pine forest, we have detected a high correlation of radial growth with air temperature and dew point in July (0.80–0.88), and even higher correlation with the night values of these parameters (0.90). Both direct and inverse correlations were found with wind velocities in May, June, and September: from 0.77 to 0.78 and from –0.84 to –0.79. An inverse correlation was observed in one of the sample plots with precipitation of May and June. Dependencies similar to the blueberry pine forest have been found in the lingonberry pine forest. A correlation with relative air humidity was found in the shrub-sphagnum forest type. Direct and inverse correlations of radial growth with wind velocity indicate its different influence on physiological processes in the leaf blade by cooling it and enhancing transpiration. Significant variability in the correlation in the blueberry forest type is probably caused by differences in the inventory parameters of the studied stands, and may also be a feature of blueberry pine forests. Generally, pine in the blueberry, lingonberry and shrub-sphagnum forest types has a similar response to the variability of meteorological factors, the main of which is the air temperature regime. Acknowledgments: The research was carried out within the framework of the state assignment No. 122011300380-5 of the N. Laverov Federal Center for Integrated Arctic Research of the Ural Branch of the Russian Academy of Sciences. For citation: Neverov N.A., Chistova Z.B., Mineev A.L. Radial Growth of Scots Pine in the Northern Taiga. Lesnoy Zhurnal = Russian Forestry Journal, 2022, no. 6, pp. 193–205. (In Russ.). https://doi.org/10.37482/0536-1036-2022-6-193-205

The Role of Tibetan Plateau–Indian Ocean Thermal Contrast in the Significant Increasing Precipitation over the Southern Tibetan Plateau in May after the Mid-1990s

Abstract This study investigates the impact of the interannual variation of Tibetan Plateau (TP)–Indian Ocean thermal contrast on southern TP precipitation in May and its changes in the mid-1990s. It is found that the southern TP precipitation is closely related to the TP–Indian Ocean thermal contrast, which could be represented by a thermal contrast index (TCI). The analysis reveals that the southern TP precipitation in May increases significantly after 1996. Meanwhile, the TCI also enhances notably. It is also found that compared with the period in 1979–96 (P1), the relationship between the southern TP precipitation and the TCI is more pronounced in 1997–2014 (P2). Further analysis shows that the meridional water vapor flux anomaly over the Arabian Sea (ABS_QV) acts as a linkage between the southern TP precipitation and the TCI. During P2, associated with the positive ABS_QV, positive water vapor flux anomalies emerge over the Arabian Sea and divide into two branches to the southwest of TP. One branch transports the moisture to the southern TP directly and forms a stronger southwesterly anomaly at the southwest edge of the TP than P1. The other branch stretches northward and imposes positive diabatic heating (Q1) anomalies over the Ural Mountains region (UMR_Q1). The results obtained by composite analysis and an anomaly atmospheric general circulation model both confirm that the UMR_Q1 anomalies can induce the wave activity propagating from the UMR_Q1 area to the TP and form the northerly anomaly over the TP, contributing to the convergence that favors the southern TP precipitation.

Impact of Climate Change on Food Security in Kazakhstan

Global food production faces immense pressure, much of which can be attributed to climate change. A detailed evaluation of the impact of climate change on the yield of staple crops in Kazakhstan, a major food exporter, is required for more scientific planting management. In this study, the Mann–Kendall test and Theil–Sen Median slope were used to determine climate trends and staple food yields over the past 30 years; random forest was used to analyze the importance of monthly climatic factors; states were classified according to climatic factors through systematic clustering method; and lastly, the influence of climate on yield was analyzed using panel regression models. The upward trend in wind speed and potato yield throughout Kazakhstan was apparent. Furthermore, barley and wheat yields had increased in the southeast. We determined that for wheat, frostbite should be prevented after the warmer winters in the high-latitude areas. Except for July–August in the low-latitude areas, irrigation water should be provided in the other growth periods and regions. As similar effects were reported for barley, the same preventive measures would apply. For potatoes, tuber rot, caused by frost or excessive precipitation in May, should be prevented in high-latitude areas; soil dryness should be alleviated during the germination and seedling stages in low-latitude areas; and irrigation and cooling should be maintained during tuber formation and maturation. Furthermore, hot dry air in March and April could damage the crops.

Assessment of the influence of weather factors on the quantitative indicators of sweet cherry fruits by Ridge regression

Sweet cherries are a favourite stone crop among consumers of fruit products. At present, the demand for sweet cherries is growing, which encourages the expansion of the varietal range of crops with different ripening periods. The purpose of this study was to develop a mathematical model for predicting the formation of fruit and sweet cherry pyrene mass depending on weather factors and varietal characteristics. The study was conducted during 2008–2019 in the conditions of the Southern Steppe zone of Ukraine on 33 varieties of sweet cherries of early, medium, and late ripening periods. The average mass of the sweet cherry fruit over the years of research was 8.41 g, and the average mass of the pyrene was 0.56 g. Late-ripening sweet cherry varieties had the best fruit mass (7.27–12.18 g). According to the maximum average mass of the fruit, the varieties Kazka, Dilema, and Kosmichna were distinguished. Sweet Erlise, Pervistok, Melitopol black and Krupnoplidna varieties had the lowest pyrene mass in sweet cherry fruits. In the group of early ripening, the best ratio of pyrene to fruit pulp was found in the Kazka variety, in medium-ripening varieties – Cordia, Perviystok, and Orion, in late-ripening varieties – Udivitelna, Krupnoplidna, and Prazdnichna.The smallest variability in sweet cherry fruit mass in the group of early-ripening varieties was detected in Sweet Erlise, in mid-ripening – Temp, and in late-ripening – Regina, while in pyrene mass – Rubinova Rannia, Vynka and Regina, respectively. Weather conditions had a dominant influence on the formation of fruit mass for all sweet cherry varieties under study, and varietal characteristics had a dominant effect on pyrene mass. The maximum influence on the formation of sweet cherry fruit mass of early varieties was provided by the indicator – the number of days with precipitation in May exceeding 1 mm, and for medium and late ripening varieties – the average monthly amount of precipitation in June. Decisive importance for the formation of pyrene mass in sweet cherry fruits of early ripening varieties was the average monthly amount of precipitation in May, in the middle ripening period – the average monthly amount of precipitation in June, in the late ripening period – the number of days with precipitation exceeding 1 mm in May.

Tree rings reveal a growth-decline event in A.D. 1875–1883 in a Tibetan plateau juniper forest

Forest declines under global warming have received much attention in studies of forest ecology, yet such events in periods before climate warming have been less studied because of shortage in documentation of past decline events. Here we used dendroecological techniques to identify forest decline events in the past five and a half centuries for a juniper forest near Lhasa of Tibet, China. Data of tree ring-widths were obtained from 42 relatively old trees after sample collection, measurement and crossdating. Radial growth of these trees was significantly and positively correlated with total precipitation in May and June. Persistent and severe growth reductions, lasting for at least eight years, were identified for each sample. We found that greater than 35% of the trees exhibited persistent and severe growth reductions in the interval A.D. 1875–1883, suggesting a growth decline event in the forest. This growth decline was the most severe event in the past five and half centuries. The weakened Indian monsoon in A.D. 1875–1878, which would result in extreme and prolonged droughts at spatially large scale in the monsoon zone, was most likely the driving force for the forest decline event discovered in this study. Our results suggested that future risk of juniper forest declines in central Tibetan plateau will be related to extreme droughts which could be amplified by warming. The study highlighted the importance of examining growth trajectory of individual trees in assessing forest health in a long perspective.

Climate-Growth Relationships of Chinese Pine (Pinus tabulaeformis Carr.) at Mt. Shiren in Climatic Transition Zone, Central China.

Simple SummaryTree rings are widely used in global change research based on the accurate dating capabilities, climate sensitivity and wide distribution of samples. In the context of global warming, the response of tree growths in north–south transition zones to climate change is one of the hot issues in Dendroecology. The research results found that trees’ growth had different responses to May–June temperature and precipitation on the north and south of the mountain. Therefore, we analyzed the relationship between tree ring and a regional hydrothermal composite factor and reconstructed its variation. The variations agree with other drought series and represent the drought variation in central and eastern monsoon regions, and may provide better understanding of drought variation and service for agricultural production.Tree ring data from the southern boundary of Chinese Pine (Pinus tabulaeformis Carr.) distribution where is the southern warm temperate margin, the paper analyzes the response of climate factors along north–south direction to tree growth. The results show that temperature and precipitation in May–June and relative moisture from March to June are main limiting factors on trees growth; however, the temperature in the south of the mountains and the moisture in the north of the mountains have relatively greater influence on trees’ growth. Additionally, we also found that the regional scPDSIMJ (that is scPDSI in May–June) was the most significant and stable factor limiting tree growth to be used for reconstruction. The reconstructed scPDSIMJ revealed that there were 29 extremely dry years and 30 extremely wet years during 1801–2016, and it could represent the drought variation in central and eastern monsoon region. The variation exists in good agreement with the reconstructed PDSI for Mt. Shennong and the drought/wetness series in Zhengzhou. Further research found that the droughts of May–June in central China were mainly impacted by local temperature and moisture (including precipitation, soil moisture, potential evaporation and water pressure), and then by the northern Pacific Ocean and the northern Atlantic Ocean. These results may provide better understanding of May–June drought variation and service for agricultural production in central China.

Intraspecific Pollen Morphology Variation and Its Responses to Environmental Factors of Wild Cathaya argyrophylla Chun Et Kuang Endemic to China

Studying the pollen morphology of this remnant and endemic wild species of Cathaya argyrophylla can be of use for paleobiologists. During this study, 23 genotypes sampled from four natural populations in two regions of Hunan Province, China. A total of 460 pollen grains were analyzed for seven quantitative and seven qualitative traits (including five new traits). Three quantitative traits (B, P, and A) (Width of the saccus (B); Length of the polar axis (P); Length of the saccus (A)) and four qualitative traits (O-CO, B-SD, O-CSR, and B-SU) (Pollen corpus outlined in the polar distal view (O-CO); Whether the outline of two sacci was distinct or not in the polar proximal view (B-SD); Roughness degree between corpus from the polar proximal view and the sacci from the polar distal view (O-CSR); Whether the overall size of two sacci was uniform or not (B-SU)) were the diagnostic pollen features that could possible to differentiate one population and classified 23 samples into two, three, or four clusters. Furthermore, 24 environmental factors were evaluated and precipitation factors effected more on pollen morphology than geographic and temperature factors, which including annual precipitation (bio12), precipitation of wettest month and driest month (bio13, bio14), precipitation seasonality (bio15) and monthly averaged precipitation in May (05-precip). The main precipitation and temperature factors exhibited positive and negative correlation with pollen size (B and E (Equatorial diameter (E))), respectively. This article provides deeper insight into intraspecific variability of pollen grains of C. argyrophylla, which have been investigated for the first time. In addition, the insights gained from this study could assist with the seed breeding and population reproduction of the endangered C. argyrophylla tree.

Influence of agrometeorological climate changes on grain productivity of spring barley in the Non‐chernozem zone of the Russian Federation

Aim . To study the influence of weather conditions on the formation of the spring barley crop under prevailing climatic changes. Material and Methods . The object of research was varieties and lines of spring barley of the FITZ Nemchinovka selection, which were studied annually in 2001‐2020 in a competitive test in the conditions of the Moscow region. According to the meteorological data for the FITZ Nemchinovka, the average monthly indicators of precipitation, air temperature and GTCM were calculated. Mathematical processing of yield data was undertaken on a computer using the Excel programme. Results . A significant increase in the average monthly air temperature during the spring‐summer season, an increase in the amount of precipitation in May and a decrease in other months of the growing season indicate a change in the climatic conditions of the region. In favorable years, with a GTCM value from 1.32 to 2.34, the average yield of barley was 5.88 t/ha and in dry years with GTCM values from 0.48 to 1.26 – 3.28 t/ha. In the spring‐summer period, there was a relatively stable variability in yield from the dynamics of precipitation and GTCM (r= 0.346...0.572). The negative correlation dependence of the yield of varieties on the average monthly air temperature throughout the season had a relatively unstable character and manifested itself as very weak or medium (r= ‐0.021...‐0.372). Conclusion . The positive yield trend observed in the conditions of the Moscow region with the annual use of the same agricultural machinery is due to an increase in the adaptive potential of new varieties and breeding lines of FITZ Nemchinovka.

Effect of Climate Change on the Growth of Tree Species: Dendroclimatological Analysis

Tree ring analyses can assist in revealing the effect of gradual change in climatic variables on tree growth. Dendroclimatic analyses are of particular importance in evaluating the climate variables that affect growth significantly and in determining the relative strength of different climatic factors. In this study, we investigated the growth performance of Pinus sylvestris, Picea abies, and Pseudotsuga menziesii in northern Germany using standard dendrochronological methods. The study further analyzed tree growth responses to different climatic variables over a period of a hundred years. Both response function analysis and moving correlation analysis confirmed that the climate and growth relationship is species-specific and variable and inconsistent over time. Scots pine and Douglas fir growth were stimulated mainly by the increase in winter temperatures, particularly the January, February, and March temperatures of the current year. In contrast, Norway spruce growth was stimulated mainly by the increase in precipitation in May, June, and July and the increase in temperature in March of the current year. Climate projections for central Europe foresee an increase in temperature and a decrease in the amount of summer precipitation. In a future, warmer climate with drier summers, the growth of Norway spruce might be negatively affected.