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One of the most important conditions in time series analysis is that time series have to be stationary. A time series is stationary in its statistical parameters when its expected value is time independent. Most time series are non-stationary. Thus it is necessary to recognize the factors causing non-stationariness and eliminate them from the time series. One of the important factors causing non-stationariness is the time series trend. In this research, the annual precipitation data set of 31 synoptic stations in the captials of the provinces in Iran during the period of 1961 to 2010 were used to investigate possible trends. The results of this study indicated that among 31 stations in the country, approximately 32 percent of the stations had a non-significant upward trend at the level of 5 percent, 9 percent of the stations had a non-significant downward trend at the 1 percent level and almost 48 percent of the stations in the country had a non-significant downward trend at the 5 percent level in the recent half-century. [ABSTRACT FROM AUTHOR]

Important autumn oilseed rape has been bred considerably in the last period as a result of the fact that it provides raw materials for the manufacture of oil, which is an alternative to unconventional fossil sources of energy, as well as for the making of some oils of superior quality used in human nutrition and not only. The experimental results from Suceavaarea during the period 2011-2012 regarding two winter rape genotypes bred at different densities are presented. The results show that at lower densities, the collum development is better and an increased resistance to wintering of the rape plant is noticed. At lower densities, higher plants, with a great number of branches per plant and a greater number of seeds and capsule per plant have been obtained. The largest grain production was achieved in both genotypes at the density of 50 plants/m². [ABSTRACT FROM AUTHOR]

In this paper is analyzed rainfall regime with rainfall indices: the amount of rainfall, conventional balance of humidity (K), emberger rainfall coefficient. Specific precipitation amounts are calculated analysis of the ecological factors that characterize either the period of accumulation of biologically active water horizon (XI-III) or maximum biological activity (VII-VIII). We performed conventional moisture balance. We calculated the average yearly rainfall in 2009-2012. We calculated the eco-climatic indices for the city of Bucharest, a city with a lot of vegetation, parks, and green spaces to highlight issues tend aridity of the region. According to the data processed, the city of Bucharest has a temperate continental climate. Specific four seasons, winter, spring, summer and autumn. Bucharest winters are very mild with little snow and relatively high temperature, while in recent years are very hot summers, very hot with little precipitation. [ABSTRACT FROM AUTHOR]

Highlights: [•] Annual precipitation and runoff variability in the Yangtze River are very low. [•] No significant trend in annual precipitation and runoff over the period 1955–2011. [•] Mean annual temperature shows significant increasing trend over the period 1955–2011. [•] Annual runoff shows little response to major developments over the period 1955–2011. [•] No climate change effect on annual precipitation or runoff in the period 1955–2011. [ABSTRACT FROM AUTHOR]

Abstract: Geostatistical models have traditionally been stationary. However, physical knowledge about underlying spatial processes often requires models with non-stationary dependence structures. Thus, there has been an interest in the literature to provide flexible models and computationally efficient methods for non-stationary phenomena. In this work, we demonstrate that the stochastic partial differential equation (SPDE) approach to spatial modelling provides a flexible class of non-stationary models where explanatory variables can be easily included in the dependence structure. In addition, the SPDE approach enables computationally efficient Bayesian inference with integrated nested Laplace approximations (INLA) available through the R-package r-inla. We illustrate the suggested modelling framework with a case study of annual precipitation in southern Norway, and compare a non-stationary model with dependence structure governed by elevation to a stationary model. Further, we use a simulation study to explore the annual precipitation models. We investigate identifiability of model parameters and whether the deviance information criterion (DIC) is able to distinguish datasets from the non-stationary and stationary models. [Copyright &y& Elsevier]

Rapid population growth and increased economic activity impose an urgent challenge on the sustainability of water resources in Beijing. Understanding the spatial and temporal variability of precipitation is of the upmost importance in order to sustain the region's water resources. Two time series, one long term (1724-2010) from a single meteorological station and a shorter time series (1980-2010) from 20 different meteorological stations within the Beijing area, were analysed using Linear Regression, Moving Average, Mann-Kendall, Rescaled Range and Spatial Interpolation methods. Results from both the long- and short-term meteorological data show a mean annual precipitation rate of 600 mm and 540 mm respectively. Annual precipitation rates have decreased during the 21st century by an estimated 100 mm or 16% in comparison to the 1990s. The 1980-2010 data show an increase in precipitation during the early 1990s followed by a sharp decrease during the subsequent years. The change of annual precipitation with time is more random and diverse in comparison to space. The main local impact factors (terrain, urbanization and elevation) and how they work on the local precipitation especially the spatial diversity are identified qualitatively. Generally speaking, (1) the annual precipitation of the plain area is more than that of the mountainous area (terrain effect), (2) the annual precipitation of the urban area in the plain area is obviously more than that of the surrounding suburb area (urbanization effect) and (3) the annual precipitation of the lower location is approximately more than that of the higher location (elevation effect). Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, we review the erosivity studies conducted in Brazil to verify the quality and representativeness of the results generated and to provide a greater understanding of the rainfall erosivity (R factor) in Brazil. We searched the ISI Web of Science, Scopus, SciELO, and Google Scholar databases and in recent theses and dissertations to obtain the following information: latitude, longitude, city, states, length of record (years), altitude, precipitation, R factor, equations calculated and respective determination coefficient (R2). We found 35 studies in Brazil that used pluviographic rainfall data to calculate the rainfall erosivity. These studies were concentrated in the cities of the south and southeast regions (~60% of all the cities studied in Brazil) with a few studies in other regions, mainly in the north. The annual rainfall erosivity in Brazil ranged from 1672 to 22,452MJmm ha−1 h−1 yr−1. The lowest values were found in the northeast region, and the highest values were found in the north region. The rainfall erosivity tends to increase from east to west, particularly in the northern part of the country. In Brazil, there are 73 regression equations to calculate erosivity. These equations can be useful to map rainfall erosivity for the entire country. To this end, techniques already established in Brazil may be used for the interpolation of rainfall erosivity, such as geostatistics and artificial neural networks. [Copyright &y& Elsevier]

Aim To assess effects of current global temperature and precipitation gradients on the trophic function of plant-herbivore-predator interactions. Specifically, I study effects of climatic gradients on factors that control herbivore abundances: top-down, bottom-up trophic cascades and plant defences. I include predictions of climate change on shifts in trophic function, under the assumption that temperature and precipitation affect the physiology and performance of plants, herbivores and predators. Location Global. Methods A search of the relevant experiments on trophic interactions was conducted using the Web of Science and Scielo databases. Strength of trophic interactions from each experiment was studied by the calculation of the log ratio effect size ( Ln R) of the control and experimental means. Each study was georeferenced and mean annual temperature ( MAT) and total annual precipitation ( TAP) were determined for each study location. Effect size of trophic interaction studies across the world were correlated with these environmental variables. Results In total, 387 effect sizes were extracted from the literature. With the exception of bottom-up trophic cascades, trophic interactions and factors controlling herbivore abundance exhibited significant linear or quadratic relationships with either temperature or precipitation gradients: plant growth, predation and the effect of plant defence on herbivores increased with temperature. In contrast, plant growth and herbivory increased with precipitation across ecosystems. Finally, top-down trophic cascades increased towards the extremes of MAT and TAP gradients. Main conclusions This study shows climatic gradients not only affect species geographic distributions and physiological tolerance but also the strength of their trophic functionality. This is especially true for the main biotic controls of herbivore populations (i.e. predation, top-down trophic cascades and plant defences). These results suggest future climate change will cause shifts in the strength of trophic interactions, resulting in increased or reduced population control of herbivores across global ecosystems. [ABSTRACT FROM AUTHOR]

The largest currently compiled database of plot runoff and soil loss data in Europe and the Mediterranean was analysed to investigate effects of land use on annual soil loss (SL), annual runoff (R) and annual runoff coefficient (RC). This database comprises 227 plot-measuring sites in Europe and the Mediterranean, with SL for 1056 plots (PL) representing 7024 plot-years (PY) and R for 804 PL representing 5327 PY. Despite large data variability, continental-wide trends are observed. Construction sites have the highest mean annual RC (57%) and SL (325 Mg.ha-1.yr-1). Bare soil, vineyards and tree crops have high mean annual RC (5–10%) and SL (10–20 Mg.ha-1.yr-1). Cropland and fallow show similar mean annual RC (8.0 and 7.3%), but lower SL (6.5 and 5.8 Mg.ha-1.yr-1). Plots with (semi-)natural vegetation cover show lowest mean annual RC (<5%) and SL (<1 Mg.ha-1.yr-1). Plot length and slope gradient correlations with R and SL depend on land-use type and are not concurrent for R and SL. Most land-use types show positive correlations between annual R and SL. Plots in cold climates have higher annual RC than plots in temperate and pan-Mediterranean climates. Annual SL in the pan-Mediterranean is less than in temperate zones, due to stony or clayey soils having a low erodibility. Annual RC in the pan-Mediterranean was higher than in temperate zones. Annual R increases strongly with increasing annual precipitation (P) above 500 mm.yr-1, while annual SL was found to stabilize at P > 500 mm.yr-1. For shrubland, annual SL was found to decrease for P > 250–500 mm.yr-1, which is attributed to an accompanying increase in vegetation cover. However, no such trend was found for R. The results allow a rapid assessment of the impact of land-use changes on annual R, RC and SL, based on field-measured plot data. [ABSTRACT FROM PUBLISHER]

Abstract: In southern Africa, multi-decadal trends over the latter half of the 20th century indicate declining mean annual precipitation, increasing variability, and increased number of warm phase ENSO events. One suggestion for the change in precipitation pattern is a shift in the global coupled ocean–atmosphere system during the late 1970s. We investigate the variability in inter-annual regional precipitation dynamics pre/post the late 1970s climate shift within the Okavango–Kwando–Zambezi (OKZ) catchment in southern Africa through a descriptive spatio-temporal analysis of rainfall patterns from 1950 to 2005. Annual precipitation totals for each basin are calculated and numbers of wet (upper tercile) and dry (lower tercile) years in two periods (1950–75 and 1980–2005) are compared. Rainfall associated with, and frequency of, El Niño Southern Oscillation (ENSO) events are also investigated. Coincidences of extremes in local and regional rainfall are examined to determine how association in precipitation patterns may vary across the catchment. Results indicate decreasing precipitation and increased dry years with warm phases of ENSO across all three sub-catchments. This has important implications for the future Kavango–Zambezi Transboundary Conservation Area (KAZA), a region that provides a vital wildlife corridor through which local precipitation and exotic streamflow constitute important water sources in an otherwise water-limited ecosystem. [Copyright &y& Elsevier]

Summary: Rainfall erosivity (R factor) has been used as a primary input parameter for soil erosion, sediment yield and water quality modeling. At least 20years of continuous high resolution rainfall data for the study area are required to compute original rainfall erosivity in (R)USLE, but such data are not available for many locations. Some simplified methods for estimating rainfall erosivity using readily available data have been presented to overcome this problem and are used in many countries. In Asia, annual precipitation is often used to estimate the R factor for (R)USLE modeling. The purpose of the present study is to evaluate models for estimating rainfall erosivity based on annual precipitation and to identify the most applicable model for Korea. Over 20years of actual rainfall erosivity data for 33 Korean weather stations calculated by high resolution precipitation data were used in this study. Correlation analyses between actual rainfall erosivity and eight rainfall parameters were investigated to identify appropriate estimators of rainfall erosivity. We found that 31 of the 33 stations indicated a strong positive relationship (r >0.5) between annual rainfall erosivity and annual precipitation with a 99% confidence level, but two stations indicated no correlation between the two variables. Twelve types of linear and nonlinear regression models were statistically evaluated for each weather station. Some parameters proved more useful to predict R factors for particular stations than annual precipitation. Nevertheless, the simplified estimation methods based on annual precipitation are still useful to predict long-term annual rainfall erosivity for the majority of locations in Korea. Finally, new simple regression models appropriate for each rain-gauge station were determined. Rainfall erosivities estimated by regression models for specific locations had limitations when used to predict actual rainfall erosivity in other locations due to site-specific conditions. Thus, simplified methods for estimating rainfall erosivity should be used with caution depending on location or period. [Copyright &y& Elsevier]

ording to the relationships among state transition probability matrixes with different step lengths, an improved Markov chain model based on autocorrelation and entropy techniques was introduced. In the improved Markov chain model, the state transition probability matrixes can be adjusted. The steps of the historical state of the event, which was significantly related to the future state of the event, were determined by the autocorrelation technique, and the impact weights of the event historical state on the event future state were determined by the entropy technique. The presented model was applied to predicting annual precipitation and annual runoff states, showing that the improved model is of higher precision than those existing Markov chain models, and the determination of the state transition probability matrixes and the weights is more reasonable. The physical concepts of the improved model are distinct, and its computation process is simple and direct, thus, the presented model is sufficiently general to be applicable to the prediction problems in hydrology and water resources. [ABSTRACT FROM AUTHOR]

Abstract: Pollen taxa of known indicator value are of great potential in the qualitative interpretation of pollen diagrams. Here we apply several numerical approaches to a lake-sediment based pollen data-set from the eastern and central Tibetan Plateau (112 samples) to assess the indicator value of Tibetan pollen taxa for modern vegetation types and for modern climate. Results from Multi-Response Permutation Procedures indicate that the differences between groups of pollen spectra originating from the same vegetation type (temperate desert, temperate steppe, alpine desert, alpine steppe, high-alpine meadow, subalpine shrub, and patchy forest) are statistically significant. Indicator Species Analyses identify several indicator taxa for most vegetation types. Multivariate regression tree analysis indicates that about 390mm of annual precipitation is the most critical threshold for the modern pollen spectra. This roughly separates desert and steppe vegetation from high-alpine meadow, subalpine shrub, and patchy forest vegetation. A strong pollen–climate relationship on the Tibetan Plateau is confirmed by the large number of statistically significant pollen taxa–climate (annual precipitation or/and annual temperature) relationships as evaluated by statistical response-modelling, involving generalised linear models. [Copyright &y& Elsevier]

Abstract: Plant yield and precipitation data from 23 to 29 years of field-based work were used to investigate the periodicity of the annual yield of Seriphidium-steppe desert (wormwood grassland) and its response to precipitation change in the lower Tianshan Mountains region, western China. There were very similar variations in annual yield (dry matter) of steppe desert with precipitation changes in most years. The annual yield (y) was estimated from precipitation (x) by a significant (P <0.01) regression model: y =−368.52+3.07x, averaged 736.35kg/ha, with 359.91mm precipitation, in the Seriphidium-gramineal grassland; and y =−420.58+3.5653x (P <0.01), Averaged 472.5kg/ha, with 252.2mm precipitation, in the Seriphidium-grassland, respectively. The spectral analysis of these data revealed the highest probability of a 10year periodic cycle of annual yield and only a weak cycle of 6year and then 16year period of the annual precipitation in the Seriphidium-gramineal grassland. Similarly, there was a high probability of a 10–12year periodic cycle of annual yield and a 16year cycle of annual precipitation in the Seriphidium-grassland. The different periodic patterns of plant yield in the study area indicated a prolonged periodic cycle of plant production when climate becomes drier. [Copyright &y& Elsevier]

Functionality of cheek teeth is essential for ruminants to masticate plant materials thoroughly and promote microbial degradation in their rumens. Thus, an excessive rate of tooth wear is expected to lead to premature loss of tooth functionality, and hence to reduced longevity. So far, however, the relationships between food habits, molar wear and longevity have not been investigated. We first compared molar wear rates among nine sika deer Cervus nippon populations with different food habits. We then investigated correlations between molar wear rate and two ecological factors, percentage of graminoids in diet and annual precipitation, relating to intrinsic and extrinsic abrasiveness of the ingested food, respectively. Secondly, we estimated ‘retained molar durability’ (molar height at a given age divided by wear rate) at successive ages for each population, and tested for correlation between molar durability and life expectancy among populations. The M1 and M3 wear rates differed among the populations and showed a positive correlation with graminoid consumption and a negative correlation with precipitation, suggesting that both ecological factors influence molar wear rates in the Japanese sika deer. M3 durability had a stronger correlation with life expectancy than M1 durability, especially at the older age stages. This implies that the influence of M3 durability on life expectancy becomes stronger at the time when the M1 is severely worn and loses its functionality, and is therefore more important for life span elongation than the M1. These results are concordant with the fact that the M3 is the most hypsodont molar in many ungulates. In the Japanese sika deer, microevolutionary acquisition of hypsodonty appears to be the case in a northern population (the Kinkazan Island), whose molar wear rates are extremely rapid due to their food habits. [ABSTRACT FROM AUTHOR]

Abstract: Holocene variations in annual precipitation (P ann) were reconstructed from pollen data from southern Argentinian Patagonia using a transfer function developed based on a weighted-averaging partial least squares (WA-PLS) regression. The pollen–climate calibration model consisted of 112 surface soil samples and 59 pollen types from the main vegetation units, and modern precipitation values obtained from a global climate database. The performance (r 2 =0.517; RMSEP=126 mm) of the model was comparable or slightly lower than in other comparable pollen–climate models. Fossil pollen data were obtained from a sediment core from Cerro Frias site (50°24''S, 72°42''W) located at the forest-steppe ecotone. Reconstructed P ann values of about 200 mm suggest dry conditions during the Pleistocene–Holocene transition (12,500–10,500 cal yr BP). P ann values were about 300–350 mm from 10,500 to 8000 cal yr BP and increased to 400–500 mm between 8000 and 1000 cal yr BP. An abrupt decrease in P ann at about 1000 cal yr BP was associated with a Nothofagus decline. The reconstructed P ann suggests a weakening and southward shift of the westerlies during the early Holocene and intensification, with no major latitudinal shifts, during the mid-Holocene at high latitudes in southern Patagonia. [Copyright &y& Elsevier]

Previous studies have shown that surface urban heat island intensity (SUHII) across cities is significantly positively correlated with mean annual precipitation (MAP), including linear and nonlinear correlations. Different explanations for these SUHII–MAP relations have been suggested, yet a systematic examination of the impact of variability in reference rural land cover on geographic variations of daytime SUHII and the relation with MAP is still lacking. In this study, the previously proposed SUHII–MAP relations are reexamined by investigating 60 cities across North America and 346 cities across the globe, respectively. The focus of the study is on the role of variability of reference land cover types in the SUHII–MAP relations. The 10-yr time series of satellite-observed land surface temperature, precipitation and solar radiation data, in conjunction with global land cover data, are used for analysis. Our results confirm the reproducibility of both the linear and nonlinear SUHII–MAP relations; nevertheless, the significant positive correlations between the daytime SUHII and the MAP are found to be dependent mainly on the variability of the reference land cover types associated with MAP levels (i.e., varying from desert to tree cover). In contrast, when a constant land cover type is taken as the reference, no significant correlations between the daytime SUHII and the MAP are observed. The finding highlights that respecting SUHI intensity as a relative measure and accounting for variability of reference land cover is of crucial importance for proper interpretation and understanding of SUHI. • Relations between SUHII and mean annual precipitation (MAP) at the global scale are reexamined. • Impact of variability of reference rural land cover on the SUHII–MAP correlations is investigated. • The significant SUHII–MAP correlations are dependent on variability of reference land cover. • The significant SUHII–MAP correlations disappear when keeping reference land cover type fixed. • Respecting SUHII as a relative measure is of great importance to interpret SUHI. [ABSTRACT FROM AUTHOR]

The article discusses a study which examines a stochastic model for the analysis of regional droughts. A drought simulation method using a multivariate generation model is presented, along with details of the effects of variation of critical parameters on the statistics of the regional drought parameters. In the study, multivariate autoregressive models were found to be efficient in maintaining the regional drought characteristics in the generated sequences. Key findings suggest that the number of regional droughts increases as the critical area ratio increases and decreases with the critical level.

Three well-dated Sabina Przewalskii ring-width chronologies from Dulan, China, have been used to reconstruct annual precipitation (from prior July to current June) variations on the northeast Tibetan Plateau since 850 AD. The reconstructions account of the instrumentally recorded precipitation variance are: 54.7% for the period of 1385–2000AD; 50.5% for 1099–1384AD and 45.7% for 850–1098AD. On the millenary scale, the precipitation variation over this region displays “W” shape, which has three peaks and two valleys. The precipitation is low during 1571–1879 AD, and high during 1880–2000 AD. 1900–2000 AD is the century with the highest precipitation over the northeast Tibetan Plateau in the last 1000 years, and 1962–2000 is the period with the highest precipitation, and the highest variability of precipitation as well in the last 1000 years. The reconstructed series also reveals that the variability of annual precipitation is large when the precipitation is more, and contrarily, variability is small when the precipitation is low. With the temperature increasing obviously in the 20th century, the precipitation in the study region significantly increased too, the variability of precipitation became larger, and drought and flooding occurred more frequently. The yearly tree-ring width (high frequency signal) series in this region reflects the local annually precipitation variation. However, the series with 40-year moving average (low frequency signal) corresponds to the Northern Hemisphere temperature variations on the decadal to centurial scale. It correlates significantly with seven temperature curves of the Northern Hemisphere in the different time spans. For example, the correlation coefficients with the most temperature curves are around 0.9 during the period of 1852–1982 AD. In general, the temperature and the precipitation change synchronously in the Dulan region. It means that low temperature corresponds to low precipitation, and vice versa. This relationship may indicate that the climatic pattern is the combination of warm-wet and cold-dry on centenary to millenary scale over the Northern Tibetan Plateau in the past 1000 years. The departure series of 40-year moving average could be regarded as the millenarian temperature curve with annual resolution over the northeast Tibetan Plateau region. [ABSTRACT FROM AUTHOR]

We examine the annual precipitation in Beijing area response to solar activity changes during the period 1749–2001. A hierarchy of changing complex periods of precipitation is carefully detected and related cycles compared with results from SN analysis. Our findings support the suggestion that solar activity influence precipitation, at least in part in Beijing. [ABSTRACT FROM AUTHOR]

The characteristics of zonal anomaly and change rule of temporal distribution of annual precipitation in the northeastern China are revealed in this paper with EOF (Empirical Orthogonal Function) and REOF (Rotated Empirical Orthogonal Function) methods and results are drawn in the standard relief maps with GIS technology for practical application. Data used in the study were obtained from 208 meteorological stations over the northeastern China from 1961 to 2001. EOF results show that the first 3 loading vectors could give entire spatial anomaly structure of annual precipitation. In the Northeast Plain including the Songneng Plain and the Liaohe Plain, there is a regional compatibility (whether wet or dry) of annual precipitation change and this precipitation pattern has occurred since the late 1980s to the present. There also exist annual precipitation patterns of wet (or dry) in south and dry (or wet) in north and wet (or dry) in east and dry (or wet) in west. REOF results display 8 principal precipitation anomaly areas by the first 8 rotated loading vectors: the west plain, the Liaodong hills, the Sanjiang Plain, the Liaoxi hills, the Changbai Mountains, the Hulun Buir Plateau, the southwest plateau and the Liaodong Peninsula. [ABSTRACT FROM AUTHOR]

Continental differences in the variability of annual runoff were reassessed using an expanded precipitation database and an improved methodology for allocating precipitation and runoff stations to Köppen climate zones. Application of the new Köppen zone allocation methodology resulted in changes in Köppen zone for 44% of runoff stations. Statistical analysis of the data, stratified by continent and Köppen climate zone, confirmed the presence of continental differences in the variability of annual runoff and the conclusions of previous research. Variability of annual runoff for temperate Australia, arid southern Africa and temperate southern Africa was found to be higher than that for other continents across the same climate zones. In this analysis a more consistent hemispheric difference in the variability of annual runoff was observed, with variability being higher in the Southern hemisphere. Previously suggested causes of the continental differences in the variability of annual runoff were also confirmed in this re-analysis. Statistically significant continental differences in the variability of annual precipitation were observed and the influence of large-scale circulation systems on precipitation variability is more apparent in this analysis than in previous work. Continental differences in the variability of annual precipitation could not account for all of the continental differences in the variability of annual runoff. The distribution of evergreen and deciduous vegetation in temperate regions remains a potential cause of the runoff variability differences. Additional potential causes identified are: continental differences in the percentage of forested catchment area, and continental differences in mean annual daily temperature range. [Copyright &y& Elsevier]

13C of 367 C3 herbaceous plants was measured in loess area in northern China. Their δ13C values vary between −21.7%. and −30.0%., with a mean of −26.7%.. In the center of Loess Plateau (semimoist area) with annual precipitation of 400–600 mm, the δ13 C values of C3 herbaceous plants range from −24.4%. to −28.5%., with a mean of −27.5%.. In the west of Loess Plateau (semiarid and arid area) with annual precipitation less than 400 mm, they range between −21.7%. and −30.0%., with a mean of −26.2%.. Annual precipitation is the main factor that makes δ13C values of C3 herbaceous plants in the west greater than those in the central Loess Plateau. The composition of δ13C in C3 plants increases with deceasing annual precipitation, and the mean change is −49%./100 mm. [ABSTRACT FROM AUTHOR]

Hydrological variable frequency analysis is a fundamental task for water resource management and water conservancy project design. Given the deficiencies of higher distribution features for the upper tail section of hydrological variable frequency curves and the corresponding safer resulting design of water conservancy projects utilizing the empirical frequency formula and Pearson type III function-based curve fitting method, the normal cloud transform algorithm-based model for hydrological variable frequency analysis was proposed through estimation of the sample empirical frequency by the normal cloud transform algorithm, and determining the cumulative probability distribution curve by overlapping calculation of multiple conceptual cloud distribution patterns, which is also the primary innovation of the paper. Its application result in northern Anhui province, China indicated that the varying trend of the cumulative probability distribution curve of annual precipitation derived from the proposed approach was basically consistent with the result obtained through the traditional empirical frequency formula. Furthermore, the upper tail section of the annual precipitation frequency curve derived from the cloud transform algorithm varied below the calculation result utilizing the traditional empirical frequency formula, which indicated that the annual precipitation frequency calculation result utilizing the cloud transform algorithm was more optimal compared to the results obtained by the traditional empirical frequency formula. Therefore, the proposed cloud transform algorithm-based model was reliable and effective for hydrological variable frequency analysis, which can be further applied in the related research field of hydrological process analysis. [ABSTRACT FROM AUTHOR]

• Plastic mulching significantly increased ET by 2.6% across the entire dataset. • Plastic mulching significantly increased SWS at 0−60 cm soil layer. • Soil water loss in deep soil was replenished during the fallow season. • Plastic mulching did not disrupt the annual equilibrium of soil water storage. • Crop yield and WUE were substantially improved under plastic mulching. In rain-fed semiarid areas, low soil water availability is a major challenge constraining crop productivity and agricultural sustainability. Soil surface mulching with plastic film has been widely used to improve soil water availability in the Loess Plateau of China. However, a systematic assessment on soil water balance dynamics under plastic mulching is still lacking. We conducted a meta-analysis on plastic mulching observations across the Loess Plateau to quantify the intensity of evapotranspiration (ET), spatiotemporal dynamics of soil water storage (SWS), and annual soil water balance in the plastic mulching systems. The results indicated that compared with non-mulching, plastic mulching significantly enhanced ET by 2.6% across the entire dataset. The magnitude of intensified ET was strongly associated with mulching pattern, mean annual precipitation and nitrogen application. Plastic mulching led to a significant increase in SWS by 8.4% at 0−60 cm soil layer, yet a decrease by 0.8% at 60−200 cm layer over the growing season, comparing with non-mulching. Importantly, an effective water recovery effect was observed at the deep soil layer under plastic mulching, as evidenced by the significantly greater SWS (+30%) over the fallow season, in comparison with that of non-mulching. Nitrogen input level and mean annual precipitation proved to be the most important factors in driving SWS. As a result, crop yield and water use efficiency were substantially improved under plastic mulching, and such enhancements were the most pronounced under full plastic mulching and lower annual mean precipitation. Increased vegetation growth due to plastic mulching can turn to impact soil water dynamics in both growing and fallow seasons, but it did not disrupt the annual equilibrium of SWS. Particularly, more precipitation storage at deep soil layer during the non-growing season appeared to fully offset the extra water loss by enhanced ET. Our findings provide critical insight into the success of plastic mulching farming practice regarding field productivity and soil water sustainability. [ABSTRACT FROM AUTHOR]

in Korea was measured to estimate the amount and pattern of genetic diversity and population structure. The mean genetic diversity within populations was 0.166. Korean alder populations have slightly high levels of genetic diversity compared to those of two Canadian alder species. The genetic differentiation among populations accounted for 9% of the total variation. The rate of gene flow was estimated high ( Nm=2.63). Analysis of inbreeding coefficient, calculated for all polymorphic loci in each population, showed a substantial heterozygote deficiency relative to Hardy-Weinberg expectations. The mean G ST value of A. hirsuta in Korea was 0.087. The low value of G ST in this species, reflecting little spatial genetic differentiation, may indicate extensive gene flow. A relationship between the mean heterozygosity and annual rainfall showed a positive relationship ( r2=0.54, F=4.67). [ABSTRACT FROM AUTHOR]

In the Loess Plateau, due to the inappropriate vegetation restoration mode, large areas of artificially restored vegetation began to degrade, thus the optimization of vegetation allocation has become an urgent necessity. The main purpose of this study was to identify and evaluate slope runoff and soil loss rates, and to review all of the plot-scale studies in the Chinese Loess Plateau, by meta-analysis. Based on data collected from the runoff plot, the effect of land use on annual runoff and annual soil loss under natural rainfall conditions was analyzed. The optimization of land use in different climatic regions of the Loess Plateau was evaluated. The plot database contained 55 plot measuring sites in the Loess Plateau, which included 461 runoff plots and 535 soil loss plots. Bare soil was found to have the highest average annual runoff (58.57 mm·yr−1) and annual soil loss (122.06 t·ha−1·yr−1). Natural grassland and mixed forest had the lowest annual runoff (<15 mm·yr−1) and annual soil loss (<20 t·ha−1·yr−1), exhibiting a better effect of soil and water conservation when the precipitation was <200 mm and >600 mm, respectively. When the precipitation was 400–600 mm, shrubland showed the lowest mean annual runoff (21.36 mm·yr−1) and annual soil loss (13.36 t·ha−1·yr−1), which conducive to reducing water and sediment. Therefore, shrubland could be selected as the recovery vegetation type in the semi-humid climatic region. Land-use types determined the relationship between annual soil loss and annual runoff with plot length and slope gradient. These results enabled the assessment of the impact of land-use change on water erosion, providing a basis for formulating soil and water conservation management programs. Unlabelled Image • The data sets of all available runoff plots in the Loess Plateau were compiled. • The optimization of the land use in the Loess Plateau was evaluated. • Evaluated the ability of different land-use types to intercept and store rainfall. • Shrubland could be preferred in the ecological management in Loess Plateau. [ABSTRACT FROM AUTHOR]

A constrained stochastic weather generator (CSWG) for producing daily mean air temperature and precipitation based on annual mean air temperature and precipitation from tree-ring records is developed and tested in this paper. The principle for stochastically generating daily mean air temperature assumes that temperatures in any year can be approximated by a sinusoidal wave function plus a perturbation from the baseline. The CSWG for stochastically producing daily precipitation is based on three additional assumptions: (1) In each month, the total precipitation can be estimated from annual precipitation if there exists a relationship between the annual and monthly precipitations. If that relationship exists, then (2) for each month, the number of dry days and the maximum daily precipitation can be estimated from the total precipitation in that month. Finally, (3) in each month, there exists a probability distribution of daily precipitation amount for each wet day. These assumptions allow the development of a weather generator that constrains statistically relevant daily temperature and precipitation predictions based on a specified annual value, and thus this study presents a unique method that can be used to explore historic (e.g., archeological questions) or future (e.g., climate change) daily weather conditions based upon specified annual values. [ABSTRACT FROM AUTHOR]

• Mountain ecosystems of Central Asia are a biodiversity hotspot under climatic risk. • Lagochilus species are key medicinal herbaceous plants native to Central Asia. • Lagochilus climate sensitivity was assessed by population structure and carbon 13. • Lagochilus populations regeneration and carbon 13 were highly sensitive to drought. • Conservation of Lagochilus should become a priority in drying Central Asia. The high-mountain ecosystems of Central Asia are a biodiversity hotspot with unique plant communities and many endemic species. Intense human pressure and global warming have caused habitat destruction in these areas and a parallel increase in the number of endangered species. Lagochilus species are key medicinal herbaceous plants native to Central Asia, many of which have been recently added to the endangered of species in Uzbekistan. To assess the climate sensitivity of Lagochilus species, we (1) located populations of six species in their native sites across Uzbekistan, and assessed their health by partitioning to ontogenetic stages along five consecutive years; (2) collected plant materials from these species, as well as from old herbarium samples (1918–1964); and (3) analyzed the carbon-13 composition in those samples, as an indicator for drouht stress. Over the course of five years (2014–2018) of continuous monitoring, fluctuations in annual precipitation in the region indicated a decrease by ∼20 %, and the fraction of young plants in each population decreased from 20–50% to 0–5 %, depending on the species. Comparing the carbon-13 composition in current and historical leaf samples showed an increase of 1.5–3.5‰ associated with a decrease in precipitation of 2–30 %, depending on the site and species. Our results show the high sensitivity of Lagochilus populations' regeneration to drying, among six species and in sites across Uzbekistan. On a multi-decadal temporal scale, the dramatic changes in carbon-13 indicate that the response to precipitation reduction is related with drought stress. Considering the expectation for drier and hotter climate in Uzbekistan in the coming decades, conservation of Lagochilus populations should become a priority in Central Asia. [ABSTRACT FROM AUTHOR]

Annual precipitation inputs to the Lake Mweru basin, Zambia, were computed from historic data and recent gridded data sets to determine historic (1925–2013) changes in lake level and their potential impacts on the important fisheries of the lake. The results highlight a period from the early 1940s to the mid-1960s when interannual variability of inputs doubled. Existing lake level data did not capture this period but they did indicate that levels were positively correlated with precipitation one to three years previously, reflecting the hydrologic storage of the lake, the inflowing Luapula River and the upstream Bangweulu wetland complex. Lag cross-correlations of rainfall to El Niño-Southern Oscillation (ENSO) and the Indian Ocean Dipole were weak and spatially and temporally discontinuous. The two drivers were generally positively correlated and induced opposing effects upon annual precipitation and lagged lake levels. This correlation became non-significant during the time of high observed interannual variability and basin inputs were prone to the vagaries of either driver independently or reinforcing drought/excess conditions. During times of high flows and persistent elevated lake levels, breeding habitat for fish increased markedly, as did nutrition supplied from the upstream wetlands. High hydrologic storage ensures that lake levels change slowly, despite contemporary precipitation totals. Therefore, good conditions for the growth of fish populations persisted for several years and populations boomed. Statistical models of biological populations indicated that such temporally autocorrelated conditions, combined with abundant habitat and nutrition can lead the "boom and bust" of fish populations witnessed historically in Lake Mweru. [ABSTRACT FROM AUTHOR]