Search

This study analyzed the daily annual precipitation data for Shanghai from 1991 to 2023, sourced from the Global Historical Climatology Network daily (GHCNd). The aim was to assess the annual precipitation trends and flood estimation and explore the relationship between return periods and annual maximum precipitation in Shanghai, China. The Mann-Kendall test identified trends in annual precipitation, while flood estimation involved calculating maximum rainfall, probability of exceedance, and return periods. Linear regression assessed the significance of the link between maximum precipitation and return periods. Results indicated a significant increase in annual precipitation over time (p <0.05). Most annual maximum precipitation events had return periods between one and five years. The highest recorded maximum precipitation was 189.5 millimeters in 2013, with a return period of 34 years. Additionally, maximum rainfall was strongly correlated with return periods (p <0.01), indicating that higher return periods are associated with increased maximum rainfall. [ABSTRACT FROM AUTHOR]

Precipitation is crucial for water resource renewal, but climate change alters their frequency and amounts, challenging societies for correct and effective water management. However, modifications of precipitation dynamics appear to be not uniformly distributed, both in space and time. Even in relatively small areas, precipitation shows the coexistence of positive and negative trends. Local topography seems to be a strong driver of precipitation changes. Understanding precipitation changes and their relationship with local topography is crucial for society's resilience. Taking advantage of a dense and long-lasting (1920–2019) meteorological monitoring network, we analyzed the precipitation changes over the last century in a sensitive and strategic area in the Mediterranean hotspot. The study area corresponds to northern Tuscany (Italy), where its topography comprises mountain ridges and coastal and river plains. Forty-eight rain gauges were selected with continuous annual precipitation time series. These were analyzed for trends and differences in mean annual precipitation between the stable period of 1921–1970 and the last 30-year 1990–2019. The relationship between precipitation changes and local topography was also examined. The results show the following highlights: (i) A general decrease in precipitation was found through the century, even if variability is marked. (ii) The mountain ridges show the largest decrease in mean annual precipitation. (iii) The precipitation change entity over the last century was not homogenous and was dependent on topography and geographical setting. (iv) A decrease in annual precipitation of up to 400 mm was found for the mountainous sites. [ABSTRACT FROM AUTHOR]

Sustainable agriculture has garnered increasing attention in recent times, with corn stalk retention constituting a pivotal component of sustainable agricultural practices. Presently, whole corn stalk retention (CCR), three-year rotation corn stalk retention (TYR), and standing corn stalk retention (SCR) are prevalent corn stalk management techniques in northeast China. However, the question of which corn stalk management technique is best suited to specific local climates within northeast China remained unanswered. Therefore, this manuscript investigates the impact of these corn stalk management practices on nitrogen (N), phosphorus (P), potassium (K), and soil organic amendments by analyzing long-term practical data. To gather data for analysis, three locations with varying latitudes were selected. The results indicate that local climate has a significant influence (p < 0.05) on the decomposition process and level of retained corn stalks. In locations with sufficient annual accumulated temperature and precipitation, a larger amount of corn stalk retention is acceptable. For instance, CCR is deemed suitable for Liaoning Province in China. Conversely, in locations lacking sufficient annual accumulated temperature or precipitation, an excessive amount of corn stalk retention cannot decay completely within a given period. Consequently, farmlands cannot adsorb adequate soil nutrients or organic matter derived from decomposed corn stalks. Thus, TYR or SCR is more appropriate for Heilongjiang Province in China. The findings of this research can guide farmers in optimizing corn stalk management practices according to specific local climates. [ABSTRACT FROM AUTHOR]

Copyright of Revista Chapingo Serie Ciencias Forestales is the property of Universidad Autonoma Chapingo and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Reanalyses are utilized for calculating climatological trends due to their focus on temporal consistency. ERA5 reanalysis family has proven to be a valuable and widely used product for trend extraction. This study specifically examines long‐term trends in total annual precipitation across two climatic hotspots: the Alps and Italy. It is acknowledged by reanalysis producers that variations in the observational systems used for data assimilation impact water cycle components like precipitation. This understanding highlights the need of assessing to what extent temporal variations in ERA5 precipitation amounts are solely a result of climate variations and the influence of changes in the observational system impacting simulation accuracy. Our research examines the differences between ERA5 and similar reanalyses against homogenized, trend‐focused observational datasets. We find that discerning the climatological signal within ERA5 adjustments for observational system variations is challenging. The trend in ERA5 from 1940 to 1970 shows distinct patterns over the Alps and, to a lesser extent, Italy, diverging from later ERA5 trends and those in other reanalyses. Notably, ERA5 shows an increasing, although nonlinear, trend in the deviation between ERA5 and the observational datasets. Improving future reanalysis interpretability could involve adopting a model‐only integration for the same period, akin to the ERA‐20C and ERA‐20CM approach. [ABSTRACT FROM AUTHOR]

Abstract.Changes in precipitation directly impact river runoff volume, subsequently influencing food production, and the security of downstream urban areas. In this study, we introduce a random velocity field (RVF) capable of performing multi-step predictions while providing interpretable insights into precipitation variations. The RVF leverages the gradient of a Gaussian random field to learn spatiotemporal velocity patterns and employs a predictive process to reduce dimensionality and enable multi-step forecasting. Bayesian parameter estimation is obtained using the Markov Chain Monte Carlo (MCMC) method. Our analysis reveals a noticeable shifting trend in annual precipitation based on diverse real datasets. This trend serves as a valuable foundation for further exploration of urban flood control and agricultural development strategies. [ABSTRACT FROM AUTHOR]

Precipitation is crucial for water resource renewal, but climate change alters their frequency and amounts, challenging societies for correct and effective water management. However, modifications of precipitation dynamics appear to be not uniformly distributed, both in space and time. Even in relatively small areas, precipitation shows the coexistence of positive and negative trends. Local topography seems to be a strong driver of precipitation changes. Understanding precipitation changes and their relationship with local topography is crucial for society’s resilience. Taking advantage of a dense and long-lasting (1920–2019) meteorological monitoring network, we analyzed the precipitation changes over the last century in a sensitive and strategic area in the Mediterranean hotspot. The study area corresponds to northern Tuscany (Italy), where its topography comprises mountain ridges and coastal and river plains. Forty-eight rain gauges were selected with continuous annual precipitation time series. These were analyzed for trends and differences in mean annual precipitation between the stable period of 1921–1970 and the last 30-year 1990–2019. The relationship between precipitation changes and local topography was also examined. The results show the following highlights: (i) A general decrease in precipitation was found through the century, even if variability is marked. (ii) The mountain ridges show the largest decrease in mean annual precipitation. (iii) The precipitation change entity over the last century was not homogenous and was dependent on topography and geographical setting. (iv) A decrease in annual precipitation of up to 400 mm was found for the mountainous sites.

Aim: Leaves display a remarkable variety of shapes, each with potential ecological advantages in specific climates. While the relations between leaf shape and either climate or height have been relatively well studied in eudicots, the macroecological drivers of shape remain poorly known in monocots. Here, we investigated the associations between climate and plant height with the evolution of leaf shape in a clade with high species and morphological diversity. Location: Global. Time period: Cretaceous to contemporary. Major taxa studied: Palms (Arecaceae). Methods: We apply a Bayesian phylogenetic mixed model to test for associations between climate and leaf shape (all – entire‐leaved, pinnate‐dissected, palmate‐dissected and costapalmate). We further reconstruct the ancestral leaf shape using multistate speciation and extinction models and compare the frequency of shapes with global temperatures through time. Results: We find that plant height associates with dissected leaves and that annual precipitation associates with pinnate shapes. The ancestral leaf shape is unclear, but early diversification was dominated by pinnate‐dissected palms, which has remained the most species‐rich form of leaves throughout palm history. Main Conclusions: Palms that are tall and live in humid regions are more likely to have pinnate leaves. Through geological time scales, temperature did not play an obvious role in determining leaf shapes. This study contributes to our understanding of how the diversity of leaf shapes is linked to biological and climatic factors. [ABSTRACT FROM AUTHOR]

Prescribed fires are one of the most effective tools to reduce the risk of wildfires but this treatment may negatively affect the hydrological and erosive response of soil, with noticeable increases in surface runoff and soil erosion. Many studies have been published on this matter but there is no consensus in the literature on the magnitude and duration of these effects since the relevant hydrological conditions are site‐specific. Moreover, the relationship between post‐fire hydrology and its main environmental drivers has been little explored. This study has carried out a bibliographic review and a meta‐analysis of the changes resulting from prescribed fire applications (water infiltration, soil water repellency (SWR), surface runoff and soil erosion) using a database of 85 case studies from 41 academic papers that have been published over the last 23 years. The effects of annual precipitation, soil slope, burn severity, fire application season, post‐fire ground cover, and vegetation type on those changes have also been statistically explored. The bibliographic review has revealed that previous case studies have not been equally distributed across the globe but concentrated in only a few countries, mainly the United States and Spain. The meta‐analysis has revealed that (i) water infiltration generally decreases and SWR appears with noticeable increases in surface runoff and soil erosion immediately after the prescribed fire, while the pre‐fire values progressively recover over time; (ii) the window of disturbance in burned soils may last a few months (with some exceptions); (iii) annual precipitation and soil slope significantly influence water infiltration and surface runoff, but not soil erosion, in both the short‐term and medium‐term; (iv) moderate‐to‐high levels of soil burn severity severely enhance surface runoff and soil erosion, and noticeably reduce water infiltration in the short‐term; (v) the level of ground cover burning is important for reducing the runoff rates, but it plays a minor role in water infiltration and soil erosion rates;and (vi) the prescribed fire applied in spring results in lower increases in short‐term runoff and erosion, while fire applications in summer and in shrublands produce the highest increases in soil loss. The following practical recommendations arise from this study: (i) research should be better distributed across all environmental contexts on a global scale; (ii) post‐fire management actions should be immediately implemented after the prescribed fire application; (iii) prescribed fire should be carried out in spring and the soil burn severity should be kept low during burning; (iv) the monitoring studies should be prolonged at least for some years (more than two or three) after prescribed fire; (iv) the catchment‐scale investigations, although more difficult and expensive, should be encouraged (avoiding, however, areas to sparsely burnt in the context of the whole catchment); (v) the monitored variables should also include the most important physical, chemical and biological properties of soil, the cover and structure of regenerating vegetation, as well as the water quality parameters; (vi) the effects of repeated applications of prescribed fire should be experimentally assessed; and (vii) guidelines for standardized and appropriate measurements and analytical methods in experimental activities should be set up. These indications support the use of land managers in the monitoring of the hydrological impacts of the prescribed fire and in the choice of sites where post‐fire management actions must be implemented. The last recommendation of this study is the creation of an experimental database supporting the bibliographic review and the meta‐analysis, which is made available to other researchers and land managers, to create a public, easily‐accessible and comprehensive tool for future research needs and professional use. [ABSTRACT FROM AUTHOR]

Copyright of Acta Scientiarum Naturalium Universitatis Sunyatseni / Zhongshan Daxue Xuebao is the property of Sun-Yat-Sen University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The length of historical records is important for analyzing trends and multidecadal variabilities in precipitation. Conventional studies usually used historical precipitation data less than 60 years, which may cause inaccurate precipitation predictions. To better understand the effects of the study period on precipitation trends and cycles, the Mann–Kendall test and Sen's slope test were applied to analyze the trend and wavelet, while the multi-temporal analysis was used to study the cycles of long historical precipitation data at four rain gauge stations in Shandong Province, China. The analysis results using long-term records show an insignificant upward trend and a longer cycle in the annual precipitation, whereas a downward trend is found when using short-term records. Furthermore, it is found that selecting the length of the representative cycle derived from the precipitation data series as the time scale for the study proved to be more reasonable. A thorough consideration of the impact of cycles on trends should, therefore, be taken to facilitate a more accurate precipitation trend analysis. HIGHLIGHTS The four representative rain stations in Shandong Province show an insignificant upward trend based on long-term records.; The length of the precipitation records affects the analysis results of the trend and cycle.; The representative cycle is the optimal period for the trend analysis of precipitation.; Different analysis periods (different initial years) with the same data length affect the trend analysis of precipitation.;

Current climate change make it increasingly important to assess the response of forest cover biomass to this change, which in turn determines the possibility of climate stabilization by reducing atmospheric CO2. Climate change projections can been linked to significant changes in water deficits and natural disturbance regimes in forest ecosystems across many parts of the world.Since the carbon-deposing potential of a plant community is determined by the biomass of assimilating organs, we focused in this article on comparative analysis of foliage biomass in the dark-coniferous genus Picea spp. and of leaved genus Quercus spp. in gradients of annual precipitation and winter temperature on the territory of Eurasia. The database for modelling involves 870 and 570 sample plots for spruce and oak correspondingly. When studying changes in the biomass of spruce and oak foliage in the hydrothermal gradients of Eurasia, we obtained statistically reliable, but surprising and paradoxical results. When the temperature increases by 1oC, the most increase in spruce foliage biomass occurs in cold regions with insufficient moisture supply, while oak leaf biomass, on the contrary, has the largest percentage of its decrease. In cold regions, as the transition from dry conditions to wet ones, the percentage of foliage mass in spruce decreases, and in oak increases. When the precipitation increases by 100 mm, there is the opposite patterns for spruce and oak: in warm regions, spruce has a decrease in the percentage of foliage mass, and oak, on the contrary, its increase. In the cold regions, these patterns change to the opposite: the spruce negative percentage changes to positive, and the oak positive percentage changes to negative. This phenomenon seems to be related to the positive ratio of photosynthesis and respiration in the spruce during the winter period when the oak does not have photosynthesis, but only respiration. It seems to be related to the fundamental difference between the winter physiology of evergreen and deciduous species, namely the ability of the former to assimilate atmospheric carbon dioxide and prolong the assimilation process beyond the vegetation period, which is usual for deciduous species. The development of such models for the main forest-forming species of Eurasia allow us to predict changes in the foliage productivity of the forest cover of Eurasia in relation to climate change.

Precipitation deficits are the main physical drivers of droughts across the globe, and their level of persistence can be characterized by the Hurst coefficient H (0.5 < H < 1), with high H indicating strong long‐term persistence (LTP). Previous analyses of point and gridded annual global precipitation datasets have concluded that LTP in precipitation is weak (H ∼ 0.6) which is inconsistent with higher values of H for large river basins, for example, the Nile. Based on an analysis of gridded annual precipitation data for eight selected regions distributed across the globe, an important new finding is that H increases with the spatial scale of averaging, with mean H values at the grid and regional scale of 0.66 and 0.83, respectively. The discovery of enhanced LTP at the regional scale of averaging of precipitation has important implications for characterizing the severity of regional droughts, as well as LTP in the annual flows of large rivers and recharge to major aquifers. Teleconnections with known modes of low frequency variability in the global climate system are demonstrated using correlation analysis and stepwise regression. Despite having several constituent regions exhibiting LTP, the Northern Hemisphere surprisingly has no LTP; this is shown to result from different modes of low frequency climatic variability canceling each other out. LTP for the Southern Hemisphere is moderate, and weak for Global average precipitation. LTP in Blue Nile basin scale precipitation is shown to explain the Hurst Phenomenon in naturalized annual flows for the River Nile, more than 70 years after its discovery by Hurst. Plain Language Summary: In the 1950s, Harold Edwin Hurst, a British physicist and hydrologist, observed that the annual river Nile flows exhibited long‐term persistence (LTP) where alternating periods of above and below average flows could be unusually long. He characterized LTP using a parameter H which increases from 0.5 (no LTP) up to a limit of 1, and found H of 0.90 for Nile flows. Analyses of long precipitation gauge records have typically given values of H in the range 0.55–0.60, leading some to conclude that precipitation could not account for the stronger LTP in the flows of the Nile and other large rivers. We analyze a long gridded global annual precipitation data set and find that, for eight selected regions, the average value of H increased from 0.66 at the grid scale to 0.83 at the regional scale of averaging. As flows in large rivers result from precipitation gathered over large upstream areas, this explains why the Nile exhibits LTP. Strong LTP at the regional scale is shown to be linked to known long‐term fluctuations in the climate system. Our findings have important implications for characterizing the risks of droughts which can extend over large areas. Key Points: For selected climatic regions, long‐term persistence in gridded annual precipitation data increases with the spatial scale of averagingLong‐term persistence at the regional scale of averaging is linked to large scale modes of fluctuation in the climate systemLong‐term persistence in basin average precipitation for the Blue Nile is shown to explain the Hurst Phenomenon for the Nile at Aswan [ABSTRACT FROM AUTHOR]

Copyright of China Rural Water & Hydropower is the property of China Rural Water & Hydropower Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Climate change over the past decades has significantly altered global hydrothermal conditions and caused an evident shift in species distribution. Predicting species distribution patterns and identifying their influencing factors will be essential in developing coping strategies to prevent species extirpation and extinction. Yet, environmental factors affecting the distribution of woody species in Central Asia remain largely unknown. Here, I used the MaxEnt model to predict the current distributions and future distribution under three SSP-RCP scenarios of six common woody species in Central Asia. The results indicated a good performance of the MaxEnt model. Precipitation of driest month and annual mean temperature were the dominant factors affecting species distribution. For the species with wide ecological niches, i.e., Acer negundo and Rosa chinensis, the suitable areas showed an evident expansion trend under future scenarios. In addition, a trend toward higher elevation was found for the species that grew at high altitudes (1600–3200 m). However, the average elevation of suitable area for A. negundo and R. chinensis firstly increased but then decreased under future scenarios. Even though the areas with high species diversity increased from 0.59% under the current situation to 0.82% and 0.81% under ssp245 in 2021–2040 and 2041–2060, respectively, species diversity showed an apparent loss in parts of the northwest and southeast areas under ssp370 and ssp585. This study can guide susceptible habitat protections under climate change. [ABSTRACT FROM AUTHOR]

We have studied the communities of soil-surface Coleoptera (Carabidae et Tenebrionidae) in the mountain hollows of Altai (Kurai and Chuya) and Tuva (Ulug-Khem and Ubsu-Nur; the arid western sector and the more humid eastern sector have been studied in the latter). Collections were made in the same habitats at intervals of about 60 years: in 1962–1963 and in 2018–2020. Climate change patterns over this period have been analyzed. In general, the climate of the characterized steppe hollows retains sharply continental features, with negative mean annual temperatures, moisture deficit, and a high frequency of fluctuations of all parameters. The average annual temperatures and the annual precipitation (during the last 10–20 years) have increased in all regions. These changes are most sharply pronounced in the Ulug-Khem hollow, creating the background for a reduction in aridity of environmental conditions. Over 60 years, the number of beetles of the studied taxa has changed several times, sometimes by more than an order of magnitude. At the same time, the number of representatives of the more xerophilic Tenebrionidae family decreased, while the number of the more mesophilic Carabidae increased. The proportions of tenebrionids in different habitats in 2018–2020 decreased significantly in comparison to the 1960s in almost all cases. More beetle species with a more northern or broader (polyzonal and/or trans-palaearctic) distribution are becoming more common in the Tuva hollows. Such species are found in both humid and arid regions. These changes in species compositions and soil-dwelling beetle communities may reflect mitigating climatic conditions due to some increase in precipitation in the studied region. The mean values of the indices of species diversity and evenness do not differ in general for the previous and current states of ecosystems. There are also no reliable differences for total species richness and total abundance. However, there are noticeable interannual differences for some diversity indices calculated for the Altai ecosystems in 2018 and 2020. This may indicate that differences between the overall diversity indices of ground beetle communities in dry and wet years overlap the long-term trend caused by climate change, and populations of species with different life strategies respond quickly to these changes without losing the overall structural complexity of the animal population. [ABSTRACT FROM AUTHOR]

Comparison of microbial diversity in the exposed surface Cambisol and paleosols buried beneath kurgans from 3900–3700 to 2400–2300 cal BC in the desert-steppe zone of the Ergeny Upland was carried out. Chemical and morphological properties of paleosols differed indicating different natural conditions of the time of kurgan erection. Microbial diversity in Ae and Bt horizons was studied by the TRFLP method. Using the RDP database, the taxonomic identification of bacterial phylotypes was carried out. Bacterial communities were diverse and reflected the functioning of soil biota, including plant and fauna pathogens. In the exposed surface soil bacterial diversity in Ae and Bt horizons differed, while in paleosols they were more similar. In the most ancient paleosol buried at 3900–3700 cal BC, bacterial groups were common to other paleosols and/or to the exposed surface soil. In contrast, two paleosols buried at the arid periods of the Bronze Age (second half of 3rd Millennium BC) had more specific bacterial groups, especially the paleosol buried on the peak of climate aridization (2400–2300 cal BC). High microbial biodiversity of buried soils of arid periods is related to the changes in the intra-annual course of precipitation. [ABSTRACT FROM AUTHOR]

Global change is influencing production and respiration in ecosystems across the globe. Lakes in particular are changing in response to climatic variability and cultural eutrophication, resulting in changes in ecosystem metabolism. Although the primary drivers of production and respiration such as the availability of nutrients, light, and carbon are well known, heterogeneity in hydrologic setting (for example, hydrological connectivity, morphometry, and residence) across and within regions may lead to highly variable responses to the same drivers of change, complicating our efforts to predict these responses. We explored how differences in hydrologic setting among lakes influenced spatial and inter annual variability in ecosystem metabolism, using high-frequency oxygen sensor data from 11 lakes over 8 years. Trends in mean metabolic rates of lakes generally followed gradients of nutrient and carbon concentrations, which were lowest in seepage lakes, followed by drainage lakes, and higher in bog lakes. We found that while ecosystem respiration (ER) was consistently higher in wet years in all hydrologic settings, gross primary production (GPP) only increased in tandem in drainage lakes. However, interannual rates of ER and GPP were relatively stable in drainage lakes, in contrast to seepage and bog lakes which had coefficients of variation in metabolism between 22–32%. We explored how the geospatial context of lakes, including hydrologic residence time, watershed area to lake area, and landscape position influenced the sensitivity of individual lake responses to climatic variation. We propose a conceptual framework to help steer future investigations of how hydrologic setting mediates the response of metabolism to climatic variability. [ABSTRACT FROM AUTHOR]

At present, the relationship between the diversity distribution patterns of different taxonomic levels of plants and climatic factors is still unclear. This paper explored the diversity pattern of vascular plant families, genera, and species in China at the municipal scale. It also studied the effects of accumulated temperature ≥ 10°C, annual precipitation, and hydrothermal base which reflect the effect of hydrothermal resources on the plant diversity pattern. The results showed that: There were extremely significant correlations among the diversities of plant families, genera, and species, and the interpretation degree of diversity between adjacent the taxonomic levels was more than 90%. The diversity pattern of plant families was mainly affected by dominant climatic state indicators such as the maximum value of accumulated temperature, annual precipitation, and hydrothermal base, and the gradient range of the hydrothermal base, which showed a clear latitudinal gradient law. The diversity pattern of plant species was found to be mainly dependent on the climatic heterogeneity indicators, being closely related to the heterogeneity indicators and sum indicators of the hydrothermal base. It was also affected by the range of precipitation gradient range. Plant genus and its diversity pattern are not only significantly affected by heterogeneity and sum indicators but also closely related to climate state indicators. In comparison with the humidity index in vegetation ecological studies, the related indicators of the hydrothermal base proposed in this paper excelled at revealing the relationship between climate and diversity patterns of plant families, genera, and species, and could effectively solve the species-area relationship issue in arid and low-temperature areas. The results of this paper have presented important theoretical and practical values for comprehensively understanding the correlation between climate and diversity of plant families, genera, and species, clarifying the impact of climate difference and climate change on plant diversity.

Human society faces problems of a global scale today, as a result of which the priorities of environmental research are shifting to the macro level, and ecology has entered the era of "big data". The authors have created a database of 1,717 model trees of Betula spp. with measured indicators of diameter at breast height (DBH), tree height, age, and aboveground biomass growing in the territory of Eurasia. Regression models for aboveground biomass components are calculated, including the dendrological indices mentioned, and two climate indicators as independent variables. Based on the theory of space-for time substitution, the obtained patterns of changes in aboveground biomass in the territorial climatic gradients of Eurasia are used to predict changes in biomass due to climate shifts. In accordance with the law of the limiting factor by Liebig, it is established that in sufficiently moisture-rich climatic zones, an increase in temperature by 1°C with a constant amount of precipitation causes an increase in biomass, and in water-deficient zones — its decrease. In warm climatic zones, a decrease in precipitation by 100 mm at a constant average January temperature causes a decrease in biomass, and in cold climatic zones - its increase. [ABSTRACT FROM AUTHOR]

【Background】 Hetao irrigation district in Inner Mongolia is the largest managed irrigation district in China. As a major grain and oil production base in western China, its agriculture relies on irrigation using water taken from the Yellow River. With available water for diversion from the river dwindling, improving irrigation water use efficiency has become increasingly important to sustain crop production in this region. One technology developed over the past few years is to use the saline groundwater as a complementary water resource in the after-autumn irrigation, with the spring and autumn irrigations using the river water. The efficacy of such alternate irrigations depends on intra-annual precipitation. 【Objective】 The purpose of this paper is to study a suitable autumn irrigation scheduling for spring maize in that it meets the requirement of the crops sown in the following spring by moistening the soil while in the meantime keeping soil salinity not exceeding a threshold value. 【Method】 The experiment was conducted at Shahaoqu experiment station in the district. Data measured from the fields were used to calibrate the SWAP-WOFOST model, and the calibrated model was then used to compare different autumn irrigation schedules for spring maize based on precipitation data measured from 1987 to 2017. 【Result】 The SWAP-WOFOST model can accurately simulate the dynamics of soil moisture, soil salt and temperature, as well as crop growth. The results indicated that in order to improve water productivity of the spring maize, the most suitable autumn irrigation amount was 200 mm, regardless of annual precipitations. We also found that the irrigation time needs to vary with precipitation pattern, started on 30 September in wet and normal years and on 30 October in dry years. 【Conclusion】 The SWAP-WOFOST model was able to simulate crop growth under different salt and water conditions, and can thus be used to help design irrigation scheduling for spring maize under different annual precipitation patterns in Hetao irrigation district and beyond.

Formulation of the problem. The article discusses changes in the main climatic characteristics in the Debed river basin (Armenia) at six meteorological stations. The aim of the work is to analyze and assess peculiar territorial distribution of the main climatic indicators in the Debed river basin, their changes over the past 80-90 years in different conditions of Armenia. Methods. To solve the set tasks, the authors used corresponding research and published works as a theoretical basis in the work. As a starting material, the work used the daily factual data of the "Center for Hydrometeorology and Monitoring" of the SNCO, Ministry of Environment of the Republic of Armenia for the period from 1930 to 2018 at six meteorological stations. The authors applied the following research methods in the article: mathematical and statistical, extrapolation, analysis, analogy, correlation, cartographic. Results. Climate of the earth has been changing rapidly over the past decades, leading to global warming. As a result, we are facing the problem of assessing the macroeconomic consequences of climate change in this territory. Armenia did not remain aloof from the problems of global climate change. On the territory of the river Debed's basin air temperature distribution and precipitation is uneven, due to the geographical latitude of the area, general and local circulation of the atmosphere, radiation energy and orographic features. We notice a decrease in air temperature and an increase in precipitation with the height of the terrain and the vertical gradient, respectively, is 0.54 ºC / 100 m and -20 mm / 100 m. The average annual air temperature ranges from 3.74 ºC to 12.3 ºC, and the annual precipitation is from 462 mm to 770 mm. Studies have also shown that long-term fluctuations in average air temperature over the year are generally characterized by positive trends. Air temperature in the basin of the river Debed increased by 1.65 °С on average over the year from 1964 to 2018. A particularly significant increase in annual temperatures has been observed after the 1990s, when the rate of annual warming reached +0.389 ºС / 10 years (for the period 1993-2018). The warmest years were 1966, 2010 and 2018. The tendency towards a decrease in the annual amount of precipitation prevails in the area. The most significant amount of precipitation decreased in the basin of the river Debed after 2002. The rate of changes in the annual amount of atmospheric precipitation for the period 2002–2018 reached -61.7 mm / 10 years, and for the entire period 1964-2018 - 1.02 mm / 10 years. On average a decrease in annual precipitation was 126 mm from 1964 to 2001, 105 mm - from 2002 to 2018 in the basin of the river Debed. There is a tendency for a slight increase in the amount of precipitation at the Stepanavan weather station.

The altitude of alpine timberline elevation has been considered to correlate with certain climatic factors. Many related isotherms (e.g., warmest month 10 °C isotherm) have been proposed to explain the altitudinal distribution of alpine timberline at the global scale. However, any climatic index actually has a wide range at the alpine timberline position worldwide. The altitudinal position of the alpine timberline is related to far more than just one climatic factor. Therefore, we developed a multivariable model for timberline elevation variability by collecting data from 473 timberline sites on the Eurasian continent. We analyzed 12 climatic variables that potentially account for timberline variation. Principal component and regression analyses were used to mine four climatic variables. The mean temperature of the warmest month (MTWM), mean temperature of the coldest month (MTCM), climatic continentality (K), and annual precipitation (AP) explained 95% of the variability of timberline elevation. MTWM, MTCM, K, and AP contributed 18%, 41.28%, 34.9%, and 5.82%, respectively, to the altitudinal distribution of alpine timberline on the whole continent; 20%, 44%, 28.86%, and 7.14% in the eastern continent; and 17.71%, 39.79%, 40.21%, and 2.29% in the western continent. We showed that MTWM, MTCM, K, and AP are deterministic factors for the altitudinal distribution of alpine timberline in the Eurasian continent. MTCM and K contributed to explaining the altitudinal distribution of timberline both in the entire, eastern, and western parts of the Eurasian continent. Our research highlights the significance of MTCM for the altitudinal distribution of timberline.

Variability and change of precipitation were investigated in Kumamoto on Kyushu Island in southwestern Japan, to assess water resources and flooding risk. Annual precipitation, annual maximum daily precipitation, and annual maximum hourly precipitation have increased over the period from 1891 to 2018 (128 years). Trends are 26.2 mm per decade, 6.07 mm/day per decade, and 2.17 mm/h/decade, respectively. Precipitation in the rainy season (June and July) is on average 37% (ranging from 12 to 59%) of annual precipitation for the 128-year period. Maximum daily precipitation in a year occurred at Kumamoto in the rainy season in 92/128 (72%) of the years of observation from 1891 to 2018, in the typhoon (August to November) season in 23/128 (18%), and in the March to May season in 12/128 (10%). This indicates that the rainy monsoon season poses the largest daily flooding risk. A wavelet analysis revealed that from 1891 to 2018 annual precipitation and daily maximum precipitation fluctuate with 2 and 4 years periods, which may be related to the El Nino-Southern Oscillation (ENSO). It is likely that air temperature rises, ENSO and topographical characteristics contributed to an increase in precipitation in the period. The analysis also showed that typhoons hitting or approaching Kumamoto have significantly affected annual precipitation and annual maximum daily precipitation, while the interval between typhoons affecting Kumamoto has been getting longer since the 1970s. HIGHLIGHTS Annual precipitation, annual maximum daily precipitation, and annual maximum hourly precipitation in Kumamoto, on Kyushu Island in southwest Japan, have increased from 1891 to 2018 (128 years). Trends are 26.2 mm per decade, 6.07 mm/day per decade, and 2.17 mm/h/decade, respectively. All three trends are statistically significant at the 1% level.; Precipitation in the rainy season (June and July) is on average 37% (ranging from 12 to 59%) of annual precipitation over the period from 1891 to 2018. The correlation between rainy season precipitation and annual precipitation is strong (R2 = 0.66, Figure 3).; Maximum daily precipitation in a year occurred at Kumamoto in the wet monsoon (June and July) season in 92/128 (72%) of the years of observation from 1889 to 2018, in the typhoon (Aug to Nov) season in 23/128 (18%) of the years of observation, and in the March to May season in 12/128 (10%) of the years of observation. This is also shown in Figure 5 and indicates that the rainy monsoon season poses the largest daily flooding risk.; A wavelet analysis revealed that precipitation in Kumamoto fluctuated from 1891 to 2018 with 2–4 years as periods, which may indicate a relationship to ENSO. It is likely that ENSO plays an important role in annual precipitation in the periods of 1890–1900, 1920–1930, 1950–1960, 1970s, and 1990–2010, because annual precipitation in a given year becomes necessarily higher or lower in phase with the ENSO.; The analysis also showed that typhoons hitting or approaching Kumamoto have significantly contributed to annual precipitation and annual maximum daily precipitation, while the interval between typhoons affecting Kumamoto has been getting slightly longer since the 1970s.;

With the continuous increase in the amount of mulch film, "white pollution" caused by plastic fragments (PF) has seriously affected agricultural production progress and poses a great threat to the safety and health of the agricultural environment. In the present study, PFs collected from 20 mulched agricultural farmlands in Sichuan Province were investigated. The PFs were separated and screened following the density flotation method. Optical microscopy was used to assess the fragments' distribution, abundance, color, size, and morphology, and Raman spectroscopy was used to identify the types. In addition, through the analysis of a questionnaire survey, a random forest (RF) model was conducted to assess the effects of environmental factors on the amount of PF. The results showed that the abundance of PFs was the highest in Lade Town, Zigong City, reaching 1158.33 ± 52.04 particles kg−1. Meanwhile, PFs were less abundant in Foyin Town, Luzhou City, with 50.00 ± 25.00 particles kg−1; the morphology features of PF in the cultivated soil were mainly transparent (60.06%) and flaky-like (83.41%), with sizes < 5 mm (63.61%). In total, 75% of the representative PFs were PE PFs, while PVC PFs were 25%. The RF model indicated that there were significant effects due to the total mulch film amount, annual precipitation, and planting pattern on the number of derived residues (PF). This study provides data indicating the urgent need to prevent and control plastic pollution in mulch farming, specifically in the soils of Sichuan Province. [ABSTRACT FROM AUTHOR]

In order to study the characteristics of climate change in the Yellow River Basin, temporal and spatial variation of precipitation from 1961 to 2019 in this basin were analyzed by using linear trend, moving average, Mann-Kendall test and empirical orthogonal function decomposition (EOF). From 1961 to 2019, the precipitation in the Yellow River Basin generally showed a downward trend, but the downward trend was not significant. 1961-1972 and 1985-2001 were two periods of annual precipitation decline. Annual precipitation increased from 1973 to 1984 and from 2002 to 2019. There was a sudden decrease for annual precipitation before or after 1964. The overall summer and winter precipitation of the Yellow River Basin showed an increasing trend but not statistically significant, while the spring and autumn showed no significant decreasing trend. Except for the upstream watersheds, which showed a significant increasing trend in winter, all watersheds showed no significant increasing or decreasing trend in the four seasons. According to EOF analysis, the first two eigenvectors of the annual precipitation field in the Yellow River basin from 1961 to 2019 can better express their spatial-temporal variation characteristics. The first modal eigenvector field shows consistent distribution and the second eigenvector field shows “northwest-southeast” antiphase distribution. According to its time coefficient, precipitation characteristics in different years in the Yellow River basin can be divided into four distribution forms of less in the whole basin, more in the whole basin, more in the southeast (less in the northwest) and more in the northwest (less in the southeast). [ABSTRACT FROM AUTHOR]

Understanding climate as a driver of low- to moderate-severity fires in the Montane Cordillera Ecozone of Canada is a priority given predicted and observed increases in frequency and severity of large fires due to climate change. We characterised historical fire-climate associations using 14 crossdated fire-scar records and tree-ring proxy reconstructions of summer drought and annual precipitation from the region. We compared fire-climate associations among years when fires burned in multiple study areas. From 1746 to 1945, there were 32 years with moderate fire synchrony in which four to six study areas recorded fire. During four high fire synchrony years, 7 to 10 study areas recorded fire. Below-average annual precipitation and summer drought synchronised fires, whereas infrequent years of high fire synchrony were preceded by a wet summer. After 1945, decreased fire occurrence and synchrony reflects fire exclusion, suppression and climatic variation. Global climate change manifests as blocking high-pressure ridges that superimpose on longer fire-seasons and increased droughts. Combined, they make dry forests increasingly susceptible to synchronous fires, which are difficult to suppress as observed during the record-breaking 2017, 2018 and 2021 fire seasons in British Columbia. From 1746 to 1945, fires commonly burned in dry forests of the Montane Cordillera Ecozone, Canada, synchronised by regional drought. Moderate-to-highly synchronous fires recurred once per 5.5 years. Post-1945 fire suppression, fuel accumulation and climate change enhanced the size and intensity of synchronous fires in 2017, 2018 and 2021 in British Columbia. [ABSTRACT FROM AUTHOR]

Abstract Background Net primary productivity (NPP) in forests plays an important role in the global carbon cycle. However, it is not well known about the increase rate of China’s forest NPP, and there are different opinions about the key factors controlling the variability of forest NPP. Methods This paper established a statistics-based multiple regression model to estimate forest NPP, using the observed NPP, meteorological and remote sensing data in five major forest ecosystems. The fluctuation values of NPP and environment variables were extracted to identify the key variables influencing the variation of forest NPP by correlation analysis. Results The long-term trends and annual fluctuations of forest NPP between 2000 and 2018 were examined. The results showed a significant increase in forest NPP for all five forest ecosystems, with an average rise of 5.2 gC·m− 2·year− 1 over China. Over 90% of the forest area had an increasing NPP range of 0–161 gC·m− 2·year− 1. Forest NPP had an interannual fluctuation of 50–269 gC·m− 2·year− 1 for the five major forest ecosystems. The evergreen broadleaf forest had the largest fluctuation. The variability in forest NPP was caused mainly by variations in precipitation, then by temperature fluctuations. Conclusions All five forest ecosystems in China exhibited a significant increasing NPP along with annual fluctuations evidently during 2000–2018. The variations in China’s forest NPP were controlled mainly by changes in precipitation.

In the Mediterranean basin, climate change signals are often representative of atmospheric transients in precipitation patterns. Remote mountaintop rainfall stations are far from human influence and can more easily unveil climate signals to improve the accuracy of long-term forecasts. In this study, the world’s longest annual precipitation time-series (1884–2021) from a remote station, the Montevergine site (1284 m a.s.l.) in southern Italy, was investigated to explain its forecast performance in the coming decades, offering a representative case study for the central Mediterranean. For this purpose, a Seasonal AutoRegressive-exogenous Time Varying process with Exponential Generalised Autoregressive Conditional Heteroscedasticity (SARX(TVAR)-EGARCH) model was developed for the training period 1884–1991, validated for the interval 1992–2021, and used to make forecasts for the time-horizon 2022–2051, with the support of an exogenous variable (dipole mode index). Throughout this forecast period, the dominant feature is the emergence of an incipient and strong upward drought trend in precipitation until 2035. After this change-point, rainfall increases again, more slightly, but with considerable values towards the end of the forecast period. Although uncertainties remain, the results are promising and encourage the use of SARX(TVAR)-EGARCH in climate studies and forecasts in mountain sites.

Copyright of Arid Zone Research / Ganhanqu Yanjiu is the property of Arid Zone Research Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Climate change has broadly impacted on the China areas. There will be severe challenges due to the variations of precipitation and temperature in the future. Therefore, a comprehensive understanding of the future climate change over China areas is desired. In this study, future annual precipitation and annual mean temperature under two SSPs over China areas were projected through multiple global climate models. Meanwhile, to explore the sources of uncertainty in projecting future climate change, the multi-factorial analysis was conducted through GCMs (five levels) and SSPs (two levels). This study can help us understand the possible changes in precipitation, temperature, and the potential extreme climate events over the China area. The results indicate that China would have more annual precipitation and higher annual mean temperature in the future. Compared with the historical period, the annual mean temperature would face a continuously increasing trend under SSPs. Regardless of SSP245 or SSP585, the growth rate of annual precipitation and annual mean temperature increase in the northern region (e.g., Northeast China, North China, and Northwest China) are higher than those in the southern parts (e.g., East China, South China, and Central China). The future temperature rise may increase the frequency of heat-related extreme climate events, which needs to be focused on in future research. Moreover, GCM was the main contributing factor to the sources of uncertainty in projecting future precipitation and SSP was the main factor for future temperature. Overall, climate change is an indisputable fact in China. The annual precipitation and annual mean temperature would increase to varying degrees in the future. Reducing the systemic bias of the climate model itself will undoubtedly be the top priority, and it would help to improve the projection and evaluation effects of relevant climate variables.

The Improvement and development of predictions in ungauged catchments require recognizing effective factors and understanding the interactions between different components of the catchments and hydrological response in different climatic zones. The most important factors affecting the flow duration curve (FDC) indices are precipitation and its characteristics. Since the flow duration curve represents the hydrologic response of watersheds, investigating and recognizing the effect of rainfall distribution on it can help to identify predictive factors for estimating the flow duration curve in ungauged catchments. The purpose of this study was to analyze the relationships between the number of rainy days and the indices FDC in the different climate zones of the country. Catchments of each climatic region were separated using the climate map of the country and overlapping it with the four-level border map of the watershed, and 314 hydrometric stations with the common period (1976–2011) in six climatic zones were selected. Flow duration curve using daily stream flow data were extracted by the Hydro Office software (2015) and indices of Q2, Q5, Q10, Q15, Q20, Q50, Q75, and Q90 were selected. The average of rainy days for each catchment was calculated and the regression relations between the FDC indices and the average of the number of rainy days in different climatic regions were extracted and analyzed. The results showed that the correlation between the indices of the first part of FDC with the number of rainy days in all selected watersheds of climatic zones had a weak and unreliable relationship for prediction and estimation of FDC in the ungauged catchments. But the relationships for the end parts of FDC (Q75 and Q90), were strong. It is noteworthy that the average coefficient of determination for the low flow indices (Q75 and Q90) with the average annual rainy days in catchments of different climatic zones was approximately equal to 0.66. This indicates the importance of the parameter of the number of rainy days as the predictor of the low flow indices associated with the end part of the FDC in different climatic zones. Therefore, it is suggested that the number of rainy days should be used as a predictive parameter for estimating the indices of the end section of FDC; its use for estimating other indices is not recommended.

With global warming, precipitation events are often prone to intensify in some regions. Understanding the changing characteristics of annual and daily extreme precipitation as well as the underlying mechanisms plays an import role for early warning of precipitation-induced disaster (e.g. floods, landslides) and water resources management, especially in densely populated urban areas. In this study, we investigate the long-term trend of annual and daily extreme precipitation in China during 1960–2010 based on daily observations from 539 meteorological stations, and the land cover map with impervious information. We find an overall increasing trend in annual and daily extreme precipitation, particularly in South-East and North-West of China. Moreover, 157 stations located in metropolitan regions experience higher increasing trends of daily extreme precipitation, particularly in Shanghai and Guangzhou metropolitan areas. It is noted that the central urban area of one metropolitan region may have significantly higher increasing trends of daily extreme precipitation than corresponding surrounding areas.

To explore the changing trend of species diversity and interspecific relationship of the forests in coastal hills of Sanya City(from east to west)from coastal rain forest to semi-deciduous monsoon forest and deciduous monsoon forest, the phytocoenological investigation methods were used to investigate those three types of vegetation communities in our field works. The species diversity in different types of vegetation were analyzed by the species richness index(dGL), Shannon-Wiener index(H), Simpson index(P)and Pielou evenness index(E). The interspecific relationships in different types of vegetations were analyzed by association coefficient(AC), co-occurrence percentage(PC)and Spearman's rank correlation coefficient test. The results were as follows:(1)Dominant species gradually changed from hygrophilous species to drought-tolerant species during the process of ecological sequence change from coastal rain forest to semi-deciduous monsoon forest and then to monsoon deciduous forest;(2)The change trend of species diversity was positively related to the annual precipitation, which decreased gradually from east to west;(3)Interspecific relationship of the three vegetation types was relatively loose; while the intensity of interspecific association in coastal rain forest was relatively high, and showed likeness between the semi-deciduous monsoon forest and deciduous monsoon forest. Those indicated that the co-existence of species was weakened from coastal rain forest to deciduous monsoon forest while the repelling competition was strengthened. In conclusion, the species composition, diversity and interspecific associations of semi-deciduous monsoon forest were more similar to those of deciduous monsoon forest. [ABSTRACT FROM AUTHOR]

As a grassland type distributed in the desert steppe with warmer climate in the steppe region of central Asia, Stipa breviflora steppe has the following characteristics, i.e. transition and vulnerability. Therefore, it is susceptible to global climate changes and anthropogenic disturbances. The resistance and resilience of a plant community to the disturbances or climate changes mainly depend on plant functional traits of the dominant species. Yet there are few studies focus on the interaction between annual precipitation and grazing pressure on the variation of plant traits of desert steppe. We investigated the functional traits of S. breviflora under contrasting annual precipitations (wet and dry years) and different long-term grazing intensities (no grazing, light grazing, moderate grazing, MG, and heavy grazing, HG), and revealed the influence of grazing and the precipitation on the variability of functional traits of S. breviflora. Moreover, we discussed the vulnerable grassland type’s adaptation mechanism to grazing disturbances and precipitation changes, and its grazing adaptation strategy under different annual rainfall precipitation conditions. Plant height, coverage, above-ground biomass, leaf length, single leaf area of S. breviflora, were sensitive to grazing interference and precipitation, while leaf dry matter content, specific leaf area, and leaf nitrogen content were inert traits. S. breviflora’s resistance and resilience in response to grazing disturbance strongly depended on rainfall conditions. In the dry year, the functional traits of S. breviflora showed higher plasticity in responses to grazing treatment, in which moderate interference was favorable for the compensatory growth of S. breviflora. The functional traits of S. breviflora were not sensitive to the drastic changes of precipitation in grazing exclusion plot for many years. It was concluded that grazing in dry year had an adverse effect on S. breviflora desert steppe, and that light grazing or banning grazing in dry years is a better management practice for the desert steppe.

With the continuous increase in the amount of mulch film, “white pollution” caused by plastic fragments (PF) has seriously affected agricultural production progress and poses a great threat to the safety and health of the agricultural environment. In the present study, PFs collected from 20 mulched agricultural farmlands in Sichuan Province were investigated. The PFs were separated and screened following the density flotation method. Optical microscopy was used to assess the fragments’ distribution, abundance, color, size, and morphology, and Raman spectroscopy was used to identify the types. In addition, through the analysis of a questionnaire survey, a random forest (RF) model was conducted to assess the effects of environmental factors on the amount of PF. The results showed that the abundance of PFs was the highest in Lade Town, Zigong City, reaching 1158.33 ± 52.04 particles kg−1. Meanwhile, PFs were less abundant in Foyin Town, Luzhou City, with 50.00 ± 25.00 particles kg−1; the morphology features of PF in the cultivated soil were mainly transparent (60.06%) and flaky-like (83.41%), with sizes < 5 mm (63.61%). In total, 75% of the representative PFs were PE PFs, while PVC PFs were 25%. The RF model indicated that there were significant effects due to the total mulch film amount, annual precipitation, and planting pattern on the number of derived residues (PF). This study provides data indicating the urgent need to prevent and control plastic pollution in mulch farming, specifically in the soils of Sichuan Province.

Formulation of the problem. The article discusses changes in the main climatic characteristics in the Debed river basin (Armenia) at six meteorological stations. The aim of the work is to analyze and assess peculiar territorial distribution of the main climatic indicators in the Debed river basin, their changes over the past 80-90 years in different conditions of Armenia. Methods. To solve the set tasks, the authors used corresponding research and published works as a theoretical basis in the work. As a starting material, the work used the daily factual data of the "Center for Hydrometeorology and Monitoring" of the SNCO, Ministry of Environment of the Republic of Armenia for the period from 1930 to 2018 at six meteorological stations. The authors applied the following research methods in the article: mathematical and statistical, extrapolation, analysis, analogy, correlation, cartographic. Results. Climate of the earth has been changing rapidly over the past decades, leading to global warming. As a result, we are facing the problem of assessing the macroeconomic consequences of climate change in this territory. Armenia did not remain aloof from the problems of global climate change. On the territory of the river Debed's basin air temperature distribution and precipitation is uneven, due to the geographical latitude of the area, general and local circulation of the atmosphere, radiation energy and orographic features. We notice a decrease in air temperature and an increase in precipitation with the height of the terrain and the vertical gradient, respectively, is 0.54 ºC / 100 m and -20 mm / 100 m. The average annual air temperature ranges from 3.74 ºC to 12.3 ºC, and the annual precipitation is from 462 mm to 770 mm. Studies have also shown that long-term fluctuations in average air temperature over the year are generally characterized by positive trends. Air temperature in the basin of the river Debed increased by 1.65 °С on average over the year from 1964 to 2018. A particularly significant increase in annual temperatures has been observed after the 1990s, when the rate of annual warming reached +0.389 ºС / 10 years (for the period 1993-2018). The warmest years were 1966, 2010 and 2018. The tendency towards a decrease in the annual amount of precipitation prevails in the area. The most significant amount of precipitation decreased in the basin of the river Debed after 2002. The rate of changes in the annual amount of atmospheric precipitation for the period 2002-2018 reached -61.7 mm / 10 years, and for the entire period 1964-2018 - 1.02 mm / 10 years. On average a decrease in annual precipitation was 126 mm from 1964 to 2001, 105 mm - from 2002 to 2018 in the basin of the river Debed. There is a tendency for a slight increase in the amount of precipitation at the Stepanavan weather station. [ABSTRACT FROM AUTHOR]

Premise: Cryptic species are evolutionarily distinct lineages lacking distinguishing morphological traits. Hidden diversity may be lurking in widespread species whose distributions cross phylogeographic barriers. This study investigates molecular and morphological variation in the widely distributed Caulanthus lasiophyllus (Brassicaceae) in comparison to its closest relatives. Methods: Fifty‐two individuals of C. lasiophyllus from across the species' range were sequenced for the nuclear ribosomal internal transcribed spacer region (ITS) and the chloroplast trnL‐F region. A subset of these samples were examined for the chloroplast ndhF gene. All 52 individuals were scored for 13 morphological traits, as well as monthly and annual climate conditions at the collection locality. Morphological and molecular results are compared with the closest relatives—C. anceps and C. flavescens—in the "Guillenia Clade." To test for polyploidy, genome size estimates were made for four populations. Results: Caulanthus lasiophyllus consists of two distinct lineages separated by eight ITS differences—eight times more variation than what distinguishes C. anceps and C. flavescens. Fewer variable sites were detected in trnL‐F and ndhF regions, yet these data are consistent with the ITS results. The two lineages of C. lasiophyllus are geographically and climatically distinct; yet morphologically overlapping. Their genome sizes are not consistently different. Conclusions: Two cryptic species within C. lasiophyllus are distinguished at the molecular, geographic, and climatic scales. They have similar genome sizes and are morphologically broadly overlapping, but an ephemeral basal leaf character may help distinguish the species. [ABSTRACT FROM AUTHOR]

Precipitation is one of the most important meteorological criteria whose quantity significantly varies throughout the earth. One of the methods to study precipitation trends in the past and present is the analysis of time series in different time scales. In this study, time series analysis was used for modeling and forecasting the average annual precipitation in Shiraz. Accordingly, the annual precipitation data in Shiraz were collected in the time interval 1951-2010. The results of this study indicated that 2.5, 5, 10, 12 and 20-year cycles cover in the study area and the third Compatible with a return period of 20-years and variance about 12 percent was dominanted in the study area. In the end, to make sure of the trend in the past and also forecasting the future precipitation, the ARIMA modeling was used. Finally, by trial and error in the ARIMA patterns family, a final pattern called M4(0,1,1) CON was selected as the optimum pattern in terms of statistical criteria. This pattern has suggested a 1.44 mm decline in precipitation until the year 2020. According to the results (the decreasing annual precipitation) and according to the climate change as a main topic, a comprehensive planning for the management of water resources unavoidable in Fars province and Shiraz city.

Evapotranspiration (ET) is the largest component of water loss from terrestrial ecosystems; however, large uncertainties exist when estimating the temporal and spatial variations of ET because of concurrent shifts in the magnitude and seasonal distribution of precipitation as well as differences in the response of ecosystem ET to environmental variabilities. In this study, we examined the impacts of precipitation seasonality and ecosystem types on ET quantified by eddy covariance towers from 2002 to 2004 in three ecosystems (grassland, deciduous broadleaf forest, and evergreen needleleaf forest) in the Yukon River Basin, Alaska. The annual precipitation changed greatly in both magnitude and seasonal distribution through the three investigated years. Observations and model results showed that ET was more sensitive to precipitation scarcity in the early growing season than in the late growing season, which was the direct result of different responses of ET components to precipitation in different seasons. The results demonstrated the importance of seasonal variations of precipitation in regulating annual ET and overshadowing the function of annual precipitation. Comparison of ET among ecosystems over the growing season indicated that ET was largest in deciduous broadleaf, intermediate in evergreen needleleaf, and lowest in the grassland ecosystem. These ecosystem differences in ET were related to differences in successional stages and physiological responses.ccccc

This paper attempts to design statistical models to forecast annual precipitation in the Neuquen and Limay river basins in the Comahue region of Argentina. These forecasts are especially useful as they are used to better organize the operation of hydro-electric dams, the agriculture in irrigated valleys and the safety of the population. In this work, multiple linear regression statistical models are built to forecast mean annual rainfall over the two river basins. Since the maximum precipitation occurs in the winter (June–August), forecasting models have been developed for the beginning of March and for the beginning of June, just before the rainy season starts. The results show that the sea-surface temperatures of the Indian and Pacific oceans are good predictors for March models and explain 42.8% of the precipitation index variance. The efficiency of the models increases in June, adding more predictors related to the autumn circulation. [ABSTRACT FROM AUTHOR]

Understanding the spatiotemporal (ST) characterization of precipitation is one key component in evaluating the climatic environment, which provides executable and effective suggestions for the implementers of climatic strategy. In this paper, the ST ordinary kriging method was used to obtain the ST distribution of annual precipitation (AP) based on the data collected from the 961 meteorological monitoring stations of the Huanghuaihai basin in China during 1956–2016. Then, stochastic site indicators were applied to quantitatively assess the ST uncertainties, and the results indicated the probability that higher precipitation (beyond 1000 mm) occurred simultaneously at any two regions was extremely low. In terms of the AP intensity analysis, the annual rainfall in 50% of the regions exceeded 500 mm, and the largest fragmentation of AP was calculated from this threshold. Furthermore, the ST characterization and the trend of AP were analyzed in different climatic environments, indicating that (1) the AP increased from west to east, exhibiting a significant gradient distribution; (2) overall, the temperature of the study area increased by approximately 0.027 °C per year, while the AP decreased by 0.2 mm per year; (3) the temperature in three subregions [high-altitude region (HAR), mid-altitude region (MAR), low-altitude region (LAR)] exhibited an increasing trend, and the significant increasing trend of temperature occurred primarily in the LAR; (4) the precipitation in the MAR and LAR exhibited a nonsignificant decreasing trend, while the precipitation in the HAR showed a significant increasing trend. [ABSTRACT FROM AUTHOR]

A comparative discussion on advantages and disadvantages of natural stands and plantations, including their productivity and resistance, began from the moment of first forest plantings and continues to this day. In the context, progressive replacement of natural forests by plantations, the question of how that will change the carbon storage capacity of forest cover when replacing natural forests with planted ones in a changing climate becomes extremely relevant. This article presents the first attempt to answer this question at the transcontinental level on a special case for two-needles pine trees (subgenus Pinus L.). The research was carried out using the database compiled by the authors on the tree biomass allocation structure for major tree species of Eurasia, in particular, the 1880 and 1967 data of naturally regenerated and planted sample pine trees, respectively. Multi-factor regression models were calculated after combining the matrix of initial data on the structure of tree biomass with the mean temperature of January and mean annual precipitation; their adequacy indices allow us to consider them reproducible. It is found that the aboveground biomass of equal-sized and equal-aged natural and planted trees increases with the rise in the temperature in the month of January and annual precipitation. This pattern is only partially valid for the branches' biomass. Iit has a specific character for the foliage one. The biomass of all components of planted trees is higher than that of natural trees, but the percentage excess varies among different components and depends on the level of January's temperature, but does not depend at all on the level of annual precipitation. The uncertainties of estimations, as well as the nature of the obtained regularities, are discussed in the text. [ABSTRACT FROM AUTHOR]

A comparative discussion of the advantages and disadvantages of natural stands and plantations, including in terms of their productivity and stability, began from the moment of the first forest plantings and continues to this day. In the context of the progressive replacement of natural forests by plantations due to deforestation, the question of how will change the carbon storage capacity of forest cover when replacing natural forests with artificial ones in a changing climate becomes extremely relevant. This article presents the first attempt to answer this question at the transcontinental level on a special case for two-needled pine trees (subgenus Pinus L.). The research was carried out using the database compiled by the authors on the single-tree biomass structure of forest-forming species of Eurasia, in particular, data of 1880 and 1967 of natural and plantation trees, respectively. Multi-factor regression models are calculated after combining the matrix of initial data on the structure of tree biomass with the mean January temperature and mean annual precipitation, and their adequacy indices allow us to consider them reproducible. It is found that the aboveground and stem biomass of equal-sized and equal-aged natural and plantation trees increases as the January temperature and precipitation rise. This pattern is only partially valid for the branches biomass, and it has a specific character for the foliage one. The biomass of all components of plantation trees is higher than that of natural trees, but the percent of this excess varies among different components and depends on the level of January temperatures, but does not depend at all on the level of annual precipitation. A number of uncertainties that arose during the modeling process, as well as the preliminary nature of the obtained regularities, are noted. [ABSTRACT FROM AUTHOR]

The hydrological properties of the clearcutting of forested catchments were widely investigated by analyzing runoff in the pre- and post-harvesting periods. Deforestation worldwide is primarily to meet the wood and fiber products demand for household and industry. It is a widely known phenomenon that deforestation enhances the streamflow and water yield. However, due to the complexity of forest structure and functions, little is known about the exact estimation of a percent increase in water yield after various harvesting intensities of conifers and broadleaved forest globally. To assess these effects, this study analyzed 145 catchments dataset collected from 21 publications. The study evaluates the influence of 25, 50, 75, and 100% deforestation on streamflow. Moreover, changes in the context of various variables like treatment years, elevation, area and mean annual precipitation were also analyzed. Overall comparison showed that after harvesting of broadleaved water yield increases up to 8-23% and in needle-leaved up to 9-28%. The study provides scientific insight into the essential role that annual precipitation, area, elevation, and year of treatment play in influencing hydrology. This research suggests that a target specific approach should be adopted in future forest management under the umbrella of integrated research to mitigate the challenges of climate change. [ABSTRACT FROM AUTHOR]