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Effects of biochar on water movement characteristics in sandy soil under drip irrigation
Shenghai PU, Guangyong LI, Guangmu TANG, Yunshu ZHANG, Wanli XU, Pan LI, Guangping FENG, Feng DING
Journal of Arid Land    2019, 11 (5): 740-753.   DOI: 10.1007/s40333-019-0106-6
Abstract171)   HTML4)    PDF (869KB)(412)      

Biochar addition can improve the physical and hydraulic characteristics of sandy soil. This study investigated the effects of biochar on water holding capacity and water movement in sandy soil under drip irrigation. By indoor simulation experiments, the effects of biochar application at five levels (0%, 1%, 2%, 4%and 6%) on the soil water retention curve, infiltration characteristics of drip irrigation and water distribution were tested and analyzed. The results showed thatbiochar addition rate was positively correlated with water holding capacity of sandy soil and soil available water. Within the same infiltration time, with an increasing amount of added biochar, the diffusion distance of the horizontal wetting front (HWF) tended to decrease, but the infiltration distance of vertical wetting front (VWF) initially declined and then rose. The features of wetted bodies changed from "broad-shallow" to "narrow-deep" type. The relationship between the transport distance of HWF and VWF and the infiltration time was described by a power function. At the same distance from the point source, the larger was the amount of added biochar, the higher was the soil water content. Biochar had a great influence on the water content of the layer with biochar (0-200mm) and had some effects at 200-250mm without biochar; but had less influence on the soil water content deeper than 250mm. For the application rate of biochar of 4%, most water was retained within 0-250mm soil layer. However, when biochar application amount was high (6%), it would be helpful for water infiltration. During the improvement of sandy soil, biochar application rate of 4% in the plow layer had the best effect.

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Effects of different loading rates and types of biochar on passivations of Cu and Zn via swine manure composting
CHEN Yan, XU Yongping, QU Fangjing, HOU Fuqin, CHEN Hongli, LI Xiaoyu
Journal of Arid Land    2020, 12 (6): 1056-1070.   DOI: 10.1007/s40333-020-0026-5
Abstract61)   HTML4)    PDF (694KB)(550)      

Pollution of arable land caused by heavy metals in livestock and poultry manure has become a potential threaten to human health in China. Safe disposal of the contained toxic pollution with animal manure by co-composting with biochar is one of the alternative methods. Biochars from different sources (wheat straw, peanut shells and rice husks) amended with different loading rates were investigated for passivations of copper and zinc (Cu and Zn) in swine manure composting. Results showed that the passivation effects of the three types of biochar on Cu and Zn were enhanced with increasing biochar dose. Contents of Cu and Zn measured by diethylenetriaminepentaacetic acid (DTPA) and Community Bureau of Reference (CBR) showed that wheat straw biochar with the loading rates of 10%-13% (w/w) was superior to the other two types of biochar in this study. Compared with the control, sample from wheat straw biochar was more favorable for the bacterial growth of Proteobacteria, Firmicutes and Actinobacteria. In addition, pot experiment showed that organic fertilizer amended with wheat straw biochar could significantly improve the growth of Chinese pakchoi and enzyme activities (superoxide dismutase, peroxidase, polyphenol oxidase and catalase) as compared with the control. Cu and Zn contents of Chinese pakchoi in the organic fertilizer group containing wheat straw biochar reduced by 73.2% and 45.2%, 65.8% and 33.6%, respectively, compared with the group without loading biochar. There was no significant difference in the contents of vitamin C and reducing sugar between the groups of organic fertilizer amended with/without wheat straw biochar, however, there was significant difference compared with the heavy metal addition group. The application of organic fertilizer formed by adding biochar can effectively reduce the adverse effects of heavy metals on crops.

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Long-term variations in runoff of the Syr Darya River Basin under climate change and human activities
Sanim BISSENBAYEVA, Jilili ABUDUWAILI, Assel SAPAROVA, Toqeer AHMED
Journal of Arid Land    2021, 13 (1): 56-70.   DOI: 10.1007/s40333-021-0050-0
Abstract91)   HTML10)    PDF (1334KB)(523)      

In this study, we analyzed the hydrological and meteorological data from the Syr Darya River Basin during the period of 1930-2015 to investigate variations in river runoff and the impacts of climate change and human activities on river runoff. The Syr Darya River, which is supplied by snow and glacier meltwater upstream, is an important freshwater source for Central Asia, as nearly half of the population is concentrated in this area. River runoff in this arid region is sensitive to climate change and human activities. Therefore, estimation of the climatic and hydrological changes and the quantification of the impacts of climate change and human activities on river runoff are of great concern and important for regional water resources management. The long-term trends of hydrological time series from the selected 11 hydrological stations in the Syr Darya River Basin were examined by non-parametric methods, including the Pettitt change point test and Mann-Kendall trend tests. It was found that 8 out of 11 hydrological stations showed significant downward trends in river runoff. Change of river runoff variations occurred in the year around 1960. Moreover, during the study period (1930-2015), annual mean temperature, annual precipitation, and annual potential evapotranspiration in the river basin increased substantially. We employed hydrological sensitivity method to evaluate the impacts of climate change and human activities on river runoff based on precipitation and potential evapotranspiration. It was estimated that human activities accounted for over 82.6%-98.7% of the reduction in river runoff, mainly owing to water withdrawal for irrigation purpose. The observed variations in river runoff can subsequently lead to adverse ecological consequences from an ecological and regional water resources management perspective.

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Biomass and carbon stocks in three types of Persian oak ( Quercus brantii var. persica) of Zagros forests in a semi-arid area, Iran
Ali MAHDAVI, Soghra SAIDI, Yaghob IRANMANESH, Mostafa NADERI
Journal of Arid Land    2020, 12 (5): 766-774.   DOI: 10.1007/s40333-020-0027-4
Abstract92)   HTML5)    PDF (252KB)(501)      

Persian oak (Quercus brantii var. persica) is a dominant tree species of Zagros forests in a semi-arid area, western Iran. However, the capacity of biomass and carbon stocks of these forests is not well studied. We selected three types of oak, i.e., seed-originated oak, coppice oak and mixed (seed-originated and coppice) oak of Zagros forests in Dalab valley, Ilam Province, Iran to survey the capacity of biomass and carbon stocks in 2018. Thirty plots with an area of 1000 m2 were systematically and randomly assigned to each type of oak. Quantitative characteristics of trees, such as diameter at breast height (DBH), height, crown diameter and the number of sprouts in each plot were measured. Then, aboveground biomass (AGB), belowground biomass (BGB), aboveground carbon stock (AGCS) and belowground carbon stock (BGCS) of each tree in plots were calculated using allometric equations. The litterfall biomass (LFB) and litterfall carbon stock (LFCS) were measured in a quadrat with 1 m×1 m in each plot. One-way analysis of variance and Duncan's test were performed to detect the differences in biomass and carbon stocks among three types of oak. Results showed that AGB, BGB and BGCS were significantly different among three types of oak. The highest values of AGB, AGCS, BGB and BGCS in seed-originated oak were 76,043.25, 14,725.55, 36,737.79 and 7362.77 kg/hm2, respectively. Also, the highest values of LFB and LFCS in seed-originated oak were 3298.33 and 1520.48 kg/hm2, respectively, which were significantly higher than those of the other two types of oak. The results imply the significant role of seed-originated oak for the regeneration of Zagros forests. Further conservation strategy of seed-originated oak is an important step in the sustainable management of Zagros forests in Iran.

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Assessment of desertification in Eritrea: land degradation based on Landsat images
G GHEBREZGABHER Mihretab, Taibao YANG, Xuemei YANG, Congqiang WANG
Journal of Arid Land    2019, 11 (3): 319-331.   DOI: 10.1007/s40333-019-0096-4
Abstract378)   HTML32)    PDF (461KB)(826)      

Remote sensing is an effective way in monitoring desertification dynamics in arid and semi-arid regions. In this study, we used a decision tree method based on NDVI (normalized difference vegetation index), SAVI (soil adjusted vegetation index), and vegetation cover proportion to quantify and analyze the desertification in Eritrea using Landsat data of the 1970s, 1980s and 2014. The results demonstrate that the NDVI value and the annual mean precipitation declined while the temperature increased over the past 40 a. Strongly desertified land increased from 4.82×104 km2 (38.5%) in the 1970s to 8.38×104 km2(66.9%) in 2014: approximately 85% of the land of the countrywas under serious desertification, which significantly occurred in arid and semi-arid lowlands of the country (eastern, northern, and western lowlands)withrelatively scarce precipitation and high temperature. The non-desertified area, mostly located in the sub-humid eastern escarpment, also declined from approximately 2.1% to 0.5%. The study concludes that the desertification is a cause of serious land degradation in Eritrea and may link to climate changes, such as low and unpredictable precipitation, and prolonged drought.

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Desert vegetationdistribution and species-environment relationshipsinan oasis-desert ecotone ofnorthwestern China
Peng ZHAO, Jianjun QU, Xianying XU, Qiushi YU, Shengxiu JIANG, Heran ZHAO
Journal of Arid Land    2019, 11 (3): 461-476.   DOI: 10.1007/s40333-019-0055-0
Abstract217)   HTML15)    PDF (452KB)(724)      

Environmental heterogeneity significantly affects the structure of ecological communities. Exploring vegetationdistribution and its relationship with environmental factorsis essential to understanding the abiotic mechanism(s)driving vegetation succession, especially in the ecologically fragile areas. In this study, based on the quantitative analysis of plant community and environmental factors in 68 plots at 10 different transects in the Minqin oasis-desert ecotone (ODE) of northwestern China, we investigated desert vegetation distribution and species-environment relationships using multivariate analysis.Two-way indicator species analysis (TWINSPAN), detrended correspondence analysis (DCA), and canonical correspondence analysis (CCA) methods were used. A total of 28 species, belonging to 27 genera in 8families,were identified. Chenopodiaceae, Zygophyllaceae, Gramineae, and Leguminosae were the largest families. Annual and perennial herbs accounted for 28.60% of the total number of plants, while shrubs (42.90%) werethe most dominant. Nitrariatangutorum was the constructive species of the desert plant community. We divided the 68plots surveyed in this study into 7 community types,according to the results of TWINSPAN. The distribution of these 7 communities in theDCAordination graph showed that species with a similar ecotype were clustered together. Results of CCA indicated that groundwater wasthe dominant factor influencing vegetation distribution, while distance between plot and oasis(Dis) and soil electrical conductivity (EC)were the local second-order factors. Our study suggests that optimizing the utilization of groundwater in oases is key to controlling the degradation of desert vegetation.The favorable topographic conditions of sand dunes should be fully utilized for vegetal dune stabilization, and the influence of soil salinity on the selection of afforestation tree species should be considered.

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Effects of water stress and NaCl stress on different life cycle stages of the cold desert annual Lachnoloma lehmannii in China
MAMUT Jannathan, Dunyan TAN, C BASKIN Carol, M BASKIN Jerry
Journal of Arid Land    2019, 11 (5): 774-784.   DOI: 10.1007/s40333-019-0015-8
Abstract148)   HTML4)    PDF (358KB)(533)      

For a plant species to complete its life cycle in arid and saline environments, each stage of the life cycle must be tolerant to the harsh environmental conditions. The aim of the study was to determine the effects of water stress (water potentials of -0.05, -0.16, -0.33, -0.56, -0.85 and -1.21 MPa) and NaCl stress (50, 100, 200, 300, 400, 500 and 600 mmol/L NaCl) on seed germination percentage, seedling survival and growth, juvenile growth and plant reproduction of Lachnoloma lehmannii Bunge (Brassicaceae), an cold desert annual that grows in the Junggar Basin of Xinjiang, China in 2010. Results indicated that low water stress (-0.05 and -0.16 MPa) had no significant effect on seed germination percentage. With a decrease in water potential, germination percentage decreased, and no seeds germinated at -0.85 and -1.21 MPa water stresses. Germination percentage of seeds was significantly affected by NaCl stress, and higher germination percentages were observed under non-saline than saline conditions. An increase in NaCl concentrations progressively inhibited seed germination percentage, and no seeds germinated at ≥400 mmol/L NaCl concentration. Non-germinated seeds were transferred from both PEG (polyethylene glycol-6000) and NaCl solutions to distilled water for seed germination recovery. The number of surviving seedlings and their heights and root lengths significantly decreased as NaCl stress increased. About 30% of the plants survived and produced fruits/seeds at 200 mmol/L NaCl concentration. Thus, seed germination, seedling establishment and reproductive stage in the life cycle of L. lehmannii are water- and salt-tolerant, with seedlings being the least tolerant. These tolerances help explain why this species can survive and produce seeds in arid and saline habitats.

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Factors determining soil water heterogeneity on the Chinese Loess Plateau as based on an empirical mode decomposition method
GONG Yidan, XING Xuguang, WANG Weihua
Journal of Arid Land    2020, 12 (3): 462-472.   DOI: 10.1007/s40333-020-0068-8
Abstract128)   HTML4)    PDF (972KB)(842)      

Soil water is a critical resource, and as such is the focus of considerable physical research. Characterization of the distribution and spatial variability of soil water content (SWC) offers important agronomic and environmental information. Estimation of non-stationary and non-linear SWC distribution at different scales is a research challenge. Based on this context, we performed a case study on the Chinese Loess Plateau, with objectives of investigating spatial variability of SWC and soil properties (i.e., soil particle composition, organic matter and bulk density), and determining multi-scale correlations between SWC and soil properties. A total of 86 in situ sampling sites were selected and 516 soil samples (0-60 cm depth with an interval of 10 cm) were collected in May and June of 2019 along the Yangling-Wugong-Qianxian transect, with a length of 25.5 km, in a typical wheat-corn rotation region of the Chinese Loess Plateau. Classical statistics and empirical mode decomposition (EMD) method were applied to evaluate characteristics of the overall and scale-specific spatial variation of SWC, and to explore scale-specific correlations between SWC and soil properties. Results showed that the spatial variability of SWC along the Yangling-Wugong-Qianxian transect was medium to weak, with a variability coefficient range of 0.06-0.18, and it was gradually decreased as scale increased. We categorized the overall SWC for each soil layer under an intrinsic mode function (IMF) number based on the scale of occurrence, and found that the component IMF1 exhibited the largest contribution rates of 36.45%-56.70%. Additionally, by using EMD method, we categorized the general variation of SWC under different numbers of IMFs according to occurrence scale, and the results showed that the calculated scales among SWC for each soil layer increased in correspondence with higher IMF numbers. Approximately 78.00% of the total variance of SWC was extracted in IMF1 and IMF2. Generally, soil texture was the dominant control on SWC, and the influence of the three types of soil properties (soil particle composition, organic matter and bulk density) was more prominent at larger scales along the sampling transect. The influential factors of soil water spatial distribution can be identified and ranked on the basis of the decomposed signal from the current approach, thereby providing critical information for other researchers and natural resource managers.

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Germination strategies of annual and short-lived perennial species in the Arabian Desert
Arvind BHATT, David J GALLACHER, Paulo R M SOUZA-FILHO
Journal of Arid Land    2020, 12 (6): 1071-1082.   DOI: 10.1007/s40333-020-0023-8
Abstract135)   HTML3)    PDF (329KB)(453)      

Germination timing is highly regulated in short-lived plant species since it strongly influences recruitment success of vegetation. In deserts, the spatiotemporal distribution of plant-available water is highly episodic and unpredictable, making winter months more favorable for seed germination when other abiotic conditions co-occur. We hypothesized that changes in photoperiod and thermoperiod would impact germination more in seeds that had undergone in situ storage. We assessed 21 annual and short-lived perennial species in the Arabian Desert to find (1) if seeds were dormant at maturity, (2) if in situ seed storage increased germination percentage compared with no storage, (3) if photoperiod and thermoperiod germination requirements were influenced by in situ storage, and (4) if a phylogenetic association in seed germination could be observed. Seeds of each species collected in early 2017 were divided into two batches. One was tested for germination within one week (fresh seeds). The other was stored in situ at the maternal location (stored seeds) until October 2017 and tested for seed germination in the first week of November. Seed germination was conducted in incubators at two thermoperiods (15°C/20°C and 20°C/30°C; 12 h/12 h), and two photoperiods (12 and 0 h light per day). Results indicated that seed germination percentages of 13 species were significantly enhanced by in situ storage. A thermoperiod response was exhibited by stored, but not fresh seeds. Light exposure increased germination of fresh seeds but had only a minimal effect on stored seeds. Germination traits exhibited no phylogenetic correlation. This result indicated that selection pressure for germination strategy was stronger than that for taxonomic traits of these desert species.

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Spatial-temporal characteristics of drought detected from meteorological data with high resolution in Shaanxi Province, China
WANG Yudan, KONG Yunfeng, CHEN Hao, DING Yongjian
Journal of Arid Land    2020, 12 (4): 561-579.   DOI: 10.1007/s40333-020-0066-x
Abstract148)   HTML18)    PDF (2112KB)(458)      

The spatial pattern of meteorological factors cannot be accurately simulated by using observations from meteorological stations (OMS) that are distributed sparsely in complex terrain. It is expected that the spatial-temporal characteristics of drought in regions with complex terrain can be better represented by meteorological data with the high spatial-temporal resolution and accuracy. In this study, Standard Precipitation Evapotranspiration Index (SPEI) calculated with meteorological factors extracted from ITPCAS (China Meteorological Forcing Dataset produced by the Institute of Tibetan Plateau Research, Chinese Academy of Sciences) was applied to identify the spatial-temporal characteristics of drought in Shaanxi Province of China, during the period of 1979-2016. Drought areas detected by SPEI calculated with data from ITPCAS (SPEI-ITPCAS) on the seasonal scale were validated by historical drought records from the Chinese Meteorological Disaster Canon-Shaanxi, and compared with drought areas detected by SPEI calculated with data from OMS (SPEI-OMS). Drought intensity, trend and temporal ranges for mutations of SPEI-ITPCAS were analyzed by using the cumulative drought intensity (CDI) index and the Mann-Kendall test. The results indicated that drought areas detected from SPEI-ITPCAS were closer to the historical drought records than those detected from SPEI-OMS. Severe and exceptional drought events with SPEI-ITPCAS lower than -1.0 occurred most frequently in summer, followed by spring. There was a general drying trend in spring and summer in Shaanxi Province and a significant wetting trend in autumn and winter in northern Shaanxi Province. On seasonal and annual scales, the regional and temporal ranges for mutations of SPEI-ITPCAS were different and most mutations occurred before the year 1990 in most regions of Shaanxi Province. The results reflect the response of different regions of Shaanxi Province to climate change, which will help to manage regional water resources.

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Ice thickness distribution and volume estimation of Burqin Glacier No. 18 in the Chinese Altay Mountains
JIN Shuang, LI Zhongqin, WANG Zemin, WANG Feiteng, XU Chunhai, AI Songtao
Journal of Arid Land    2020, 12 (6): 905-916.   DOI: 10.1007/s40333-020-0083-9
Abstract117)   HTML17)    PDF (2563KB)(566)      

Information on the thickness distribution and volume of glacier ice is highly important for glaciological applications; however, detailed measurements of the ice thickness of many glaciers in the Chinese Altay Mountains remain lacking. Burqin Glacier No. 18 is a northeast-orientated cirque glacier located on the southern side of the Altay Mountains. This study used PulseEKKO® PRO 100A enhancement ground-penetrating radar (GPR) to survey the ice thickness and volume of Burqin Glacier No. 18 in summer 2018. Together with GPR surveying, spatial distributed profiles of the GPR measurements were concurrently surveyed using the real-time kinematic (RTK) global navigation satellite system (GNSS, Unistrong E650). Besides, we used QuickBird, WorldView-2, and Landsat TM to delineate accurate boundary of the glacier for undertaking estimation of glacier ice volume. GPR measurements revealed that the basal topography of profile B1-B2 was flat, the basal topography of profile C1-C2 presented a V-type form, and the basal topography of profile D1-D2 had a typical U-type topographic feature because the bedrock near the central elevation of the glacier was relatively flat. The longitudinal profile A1-A2 showed a ladder-like distribution. Glacier ice was thin at the terminus and its thickness increased gradually from the elevation of approximately 2620 m a.s.l. along the main axis of the glacier tongue with an average value of 80 (±1) m. The average ice thickness of the glacier was determined as 27 (±2) m and its total ice volume was estimated at 0.031 (±0.002) km3. Interpretation of remote sensing images indicated that during 1989-2016, the glacier area reduced from 1.30 to 1.17 km2 (reduction of 0.37%/a) and the glacier terminus retreated at the rate of 8.48 m/a. The mean ice thickness of Burqin Glacier No. 18 was less than that of the majority of other observed glaciers in China, especially those in the Qilian Mountains and Central Chinese Tianshan Mountains; this is probably attributable to differences in glacier type and climatic setting.

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Spatial and temporal patterns of the inter-annual oscillations of glacier mass over Central Asia inferred from Gravity Recovery and Climate Experiment (GRACE) data
Chuandong ZHU, Yang LU, Hongling SHI, Zizhan ZHANG
Journal of Arid Land    2017, 9 (1): 87-97.   DOI: 10.1007/s40333-016-0021-z
Abstract1053)   HTML2)    PDF (432KB)(1336)      

Monitoring glacier mass balance is crucial to managing water resources and also to understanding climate change for the arid and semi-arid regions of Central Asia. This study extracted the inter-annual oscillations of glacier mass over Central Asia from the first ten principal components (S-PCs) of filtered variability via multichannel singular spectral analysis (MSSA), based on gridded data of glacier mass inferred from Gravity Recovery and Climate Experiment (GRACE) data obtained from July 2002 to March 2015. Two significant cycles of glacier mass balance oscillations were identified. The first cycle with a period of 6.1-year accounted for 54.5% of the total variance and the second with a period of 2.3-year accounted for 4.3%. The 6.1-year oscillation exhibited a stronger variability compared with the 2.3-year oscillation. For the 6.1-year oscillation, the results from lagged cross-correlation function suggested that there were significant correlations between glacier mass balances and precipitation variations with the precipitation variations leading the response of glacier mass balances by 9-16 months.

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Hydraulic resistance partitioning between shoot and root system and plant water status of Haloxyolon ammodendron growing at sites of contrasting soil texture
GuiQing XU, Yan LI, Ting ZOU
Journal of Arid Land    DOI: 10.3724/SP.J.1227.2010.00098
Abstract2482)      PDF (427KB)(2835)      
Hydraulic resistance components and water relations were studied on Haloxyolon ammodendron, a small xeric tree, growing at sites significantly differed in soil texture. Soil water content, leaf water potential (ψl), xylem water potential (ψx), root water potential (ψroot), leaf transpiration rate (TR) and stomatal conductance (gs) were measured at the two sites during the growing season of 2005 and 2006. Leaf specific hydraulic resistance (Rplant) during the whole growing season, hydraulic resistance of plants (Rp), shoots (Rshoot) and roots (Rroot) in the August of both years were calculated and expressed on leaf area basis. The results showed the proportion of the hydraulic resistance of the aerial part (Rshoot) to the Rp was the same to the proportion of the hydraulic resistance of the soil part (Rroot) to the Rp, indicating that both parts were equivalent important to plant water hydraulic system from soil to leaf. Positive significant correlations were found between Rp and Rroot, suggesting that root hydraulics resistance was a major determinant of plant hydraulic resistance (Rp) and transpiration rate. The integrated effect of stomatal control, hydraulic regulation and morphology adjustment enabled plants at heavy soil site surviving the extreme water deficit period.
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Sand particle lift-off velocity measurements and numerical simulation of mass flux distributions in a wind tunnel
Fengjun XIAO, Zhibao DONG, Liejin GUO, Yueshe WANG, Debiao LI
Journal of Arid Land    2017, 9 (3): 331-344.   DOI: 10.1007/s40333-017-0096-1
Abstract719)   HTML1)    PDF (704KB)(1359)      

Lift-off velocity of saltating sand particles in wind-blown sand located at 1.0 mm above the sand bed surface was measured using a phase Doppler particle analyzer in a wind tunnel. The results show that the probability distribution of lift-off velocity can be expressed as a lognormal function, while that of lift-off angle follows an exponential function. The probability distribution of lift-off angle conditioned for each lift-off velocity also follows an exponential function, with a slope that becomes steeper with increasing lift-off velocity. This implies that the probability distribution of lift-off velocity is strongly dependent on the lift-off angle. However, these lift-off parameters are generally treated as an independent joint probability distribution in the literature. Numerical simulations were carried out to investigate the effects of conditional versus independent joint probability distributions on the vertical sand mass flux distribution. The simulation results derived from the conditional joint probability distribution agree much better with experimental data than those from the independent ones. Thus, it is better to describe the lift-off velocity of saltating sand particles using the conditional joint probability distribution. These results improve our understanding of saltation processes in wind-blown sand.

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Evaluating agricultural water-use efficiency based on water footprint of crop values: a case study in Xinjiang of China
HAI Yang, LONG Aihua, ZHANG Pei, DENG Xiaoya, LI Junfeng, DENG Mingjiang
Journal of Arid Land    2020, 12 (4): 580-593.   DOI: 10.1007/s40333-020-0058-x
Abstract119)   HTML6)    PDF (665KB)(499)      

Efficient agricultural water use is crucial for food safety and water conservation on a global scale. To quantitatively investigate the agricultural water-use efficiency in regions exhibiting the complex agricultural structure, this study developed an indicator named water footprint of crop values (WFV) that is based on the water footprint of crop production. Defined as the water volume used to produce a unit price of crop (m3/CNY), the new indicator makes it feasible to directly compare the water footprint of different crops from an economic perspective, so as to comprehensively evaluate the water-use efficiency under the complex planting structure. On the basis of WFV, the study further proposed an indicator of structural water-use coefficient (SWUC), which is represented by the ratio of water-use efficiency for a given planting structure to the water efficiency for a reference crop and can quantitatively describe the impact of planting structure on agricultural water efficiency. Then, a case study was implemented in Xinjiang Uygur Autonomous Region of China. The temporal and spatial variations of WFV were assessed for the planting industries in 14 prefectures and cities of Xinjiang between 1991 and 2015. In addition, contribution rate analysis of WFV for different prefectures and cities was conducted to evaluate the variations of WFV caused by different influencing factors: agricultural input, climatic factors, and planting structure. Results from these analyses indicated first that the average WFV of planting industries in Xinjiang significantly decreased from 0.293 m3/CNY in 1991 to 0.153 m3/CNY in 2015, corresponding to an average annual change rate of -3.532%. WFV in 13 prefectures and cities (with the exception of Karamay) has declined significantly during the period of 1991-2015, indicating that agricultural water-use efficient has effectively improved. Second, the average SWUC in Xinjiang decreased from 1.17 to 1.08 m3/CNY in the 1990s, and then declined to 1.00 m3/CNY in 2011-2015. The value of SWUC was highly consistent with the relative value of WFV in most prefectures and cities, showing that planting structure is one of the primary factors affecting regional agricultural water-use efficiency. Third, the contribution rate of WFV variations from human factors including agricultural input and planting structure was much more significant than that from climatic factors. However, the distribution of agricultural input and the adjustment of planting structure significantly differed among prefectures and cities, suggesting regional imbalances of agricultural development. This study indicated the feasibility and effectiveness of controlling agricultural water use through increasing technical input and rational selection of crops in the face of impending climate change. Specifically, we concluded that, the rational application of chemical fertilizers, the development of the fruit industry, and the strict restriction of the cotton industry should be implemented to improve the agricultural water-use efficiency in Xinjiang.

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Spatial-temporal variations in near-surface soil freeze-thaw cycles in the source region of the Yellow River during the period 2002-2011 based on the Advanced Microwave Scanning Radiometer for the Earth Observing System (AMSR-E) data
Rui WANG, Qingke ZHU, Hao MA, Ning AI
Journal of Arid Land    2017, 9 (6): 850-864.   DOI: 10.1007/s40333-017-0032-4
Abstract288)   HTML5)    PDF (665KB)(645)      

Detecting near-surface soil freeze-thaw cycles in high-altitude cold regions is important for understanding the Earth’s surface system, but such studies are rare. In this study, we detected the spatial-temporal variations in near-surface soil freeze-thaw cycles in the source region of the Yellow River (SRYR) during the period 2002-2011 based on data from the Advanced Microwave Scanning Radiometer for the Earth Observing System (AMSR-E). Moreover, the trends of onset dates and durations of the soil freeze-thaw cycles under different stages were also analyzed. Results showed that the thresholds of daytime and nighttime brightness temperatures of the freeze-thaw algorithm for the SRYR were 257.59 and 261.28 K, respectively. At the spatial scale, the daily frozen surface (DFS) area and the daily surface freeze-thaw cycle surface (DFTS) area decreased by 0.08% and 0.25%, respectively, and the daily thawed surface (DTS) area increased by 0.36%. At the temporal scale, the dates of the onset of thawing and complete thawing advanced by 3.10 (±1.4) and 2.46 (±1.4) days, respectively; and the dates of the onset of freezing and complete freezing were delayed by 0.9 (±1.4) and 1.6 (±1.1) days, respectively. The duration of thawing increased by 0.72 (±0.21) day/a and the duration of freezing decreased by 0.52 (±0.26) day/a. In conclusion, increases in the annual minimum temperature and winter air temperature are the main factors for the advanced thawing and delayed freezing and for the increase in the duration of thawing and the decrease in the duration of freezing in the SRYR.

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Isolation and identification of desert habituated arbuscular mycorrhizal fungi newly reported from the Arabian Peninsula
Sarah SYMANCZIK, Janusz B?ASZKOWSKI, Sally KOEGEL, Thomas BOLLER, Andres WIEMKEN, Mohamed N AL-YAHYA'EI.
Journal of Arid Land    2014, 6 (4): 488-497.   DOI: 10.1007/s40333-014-0021-9
Abstract1931)      PDF (378KB)(3748)      
Arbuscular mycorrhizal fungi (AMF) are known to facilitate the growth and vigour of many plants, particularly in arid ecosystems. In a survey of AMF in a date palm plantation and two natural sites of a desert in Oman, we generated many single spore-derived cultures of AMF. We identified a number of these isolates based on spore morphotyping and molecular phylogenetic analysis using the sequence of the LSU-rDNA. Here, we presented the characteristics of four species of AMF recovered, namely Claroideoglomus drummondii, Diversispora aurantia, Diversispora spurca and Funneliformis africanum. The four species have been described previously, but for the Arabian Peninsula they are reported here for the first time. Our endeavor of isolation and characterization of some AMF habituated to arid sites of Arabia represents a first step towards application for environmental conservation and sustainable agriculture in this region.
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Heavy metal contamination of urban topsoil in a petrochemical industrial city in Xinjiang, China
WANG Wei, LAI Yingshuai, MA Yuanyuan, LIU Zilong, WANG Shufen, HONG Chenglin
Journal of Arid Land    2016, 8 (6): 871-880.   DOI: 10.1007/s40333-016-0057-0
Abstract919)      PDF (280KB)(1454)      
Heavy metal pollution is a widespread phenomenon in many countries of the world. In this study, we conducted a field investigation to assess the status of heavy metal pollution in urban soils of Dushanzi, a district of Karamay city in Xinjiang, China. A total of 56 soil samples in the topsoil layer of 0–15 cm were collected within the urban area and seven elements (Cu, Zn, Cd, Pb, Cr, As and Ni) were analyzed. The mean concentrations of these metals were all higher than their corresponding background values of soils in Xinjiang. We used the pollution index and ecological risk index to assess the degree of heavy metal pollution and the potential ecological risk of urban soils. The pollution index values of Cu, Zn, Cd, Pb, Cr, As and Ni were 1.81, 1.35, 4.64, 1.27, 1.80, 1.39 and 1.22, respectively; and the potential ecological risk index values for them were 12.03, 1.79, 185.05, 8.39, 4.78, 18.44 and 1.79, respectively. These results indicated that urban soils in Dushanzi were polluted by heavy metals to some extent and demonstrated a high ecological risk, as influenced by industrial activities. Cd was the key element for the metal pollution of urban soils in the study area. Correlation analyses, principal component analysis coupled with the spatial distribution maps of element concentrations further revealed that heavy metal pollution of urban soils can be mainly attributed to petrochemical industry, coal chemical industry, traffic and commercial activities.
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Interaction between climate and management on beta diversity components of vegetation in relation to soil properties in arid and semi-arid oak forests, Iran
MEHDI Heydari, FATEMEH Aazami, MARZBAN Faramarzi, REZA Omidipour, MASOUD Bazgir, DAVID Pothier, BERNARD Prévosto
Journal of Arid Land    2019, 11 (1): 43-57.   DOI: 10.1007/s40333-018-0024-z
Abstract238)   HTML5)    PDF (310KB)(694)      

This study aimed to investigate the interaction between regions with different climatic conditions (arid vs. semi-arid) and management (protected vs. unprotected) on the turnover and nestedness of vegetation in relation to physical, chemical and biological properties of soils in the Ilam Province of Iran. In each of the two regions, we sampled 8 sites (4 managed and 4 unmanaged sites) within each of which we established 4 circular plots (1000 m2) that were used to investigate woody species, while two micro-plots (1 m×1 m) were established in each 1000-m2 plot to analyze herbaceous species. In each sample unit, we also extracted three soil samples (0-20 cm depth) for measuring soil properties. The results indicated that the interaction between region and conservational management significantly affected the percent of canopy cover of Persian oak (Quercus brantii Linddl), soil respiration, substrate-induced respiration, as well as beta and gamma diversities and turnover of plant species. The percent of oak canopy cover was positively correlated with soil silt, electrical conductivity, available potassium, and alpha diversity, whereas it was negatively correlated with plant turnover. In addition, plant turnover was positively related to available phosphorus, while nestedness of species was positively related to organic carbon and total nitrogen. According to these results, we concluded that physical, chemical, and biological characteristics of limited ecological niche generally influenced plant diversity. Also, this study demonstrated the major contribution of the beta diversity on gamma diversity, especially in semi-arid region, because of the higher heterogeneity of vegetation in this area.

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Growth of the Sayram Lake and retreat of its water-supplying glaciers in the Tianshan Mountains from 1972 to 2011
CHENG Weiming, WANG Nan, ZHAO Shangmin, FANG Yue, ZHAO Min
Journal of Arid Land    2016, 8 (1): 13-22.   DOI: 10.1007/s40333-015-0139-4
Abstract1325)      PDF (249KB)(1997)      
Inland lakes and alpine glaciers are important constituents of water resources in arid and semiarid regions. Understanding their variations is critical for both an accurate evaluation of the dynamic changes of water resources and the retrieval of climatic information. On the basis of earlier researches, this study investigated the growth of the Sayram Lake and the retreat of its water-supplying glaciers in the Tianshan Mountains using long-term sequenced remote sensing images. Our results show that over the past 40 years, the surface area and the water level of the lake has increased by 12.0±0.3 km 2 and 2.8 m, respectively, and the area of its water-supplying glaciers has decreased continuously since the early 1970s with a total reduction of about –2.13±0.03 km 2. Our study has indicative significance to the research of regional climate change.
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Revision of two species of Calligonum from the desert of Xinjiang, Northwestern China
Ying FENG, BoRong PAN, GuanMian SHEN
Journal of Arid Land    DOI: 10.3724/SP.J.1227.2010.00231
Abstract2958)      PDF (145KB)(2277)      
By examination of Calligonum pumilum A. Los. and Calligonum ruoqiangense Liou f., collected from natural habitats, and the analysis of their variance, this paper revealed that the morphological characters of these specimens are quite different from each other, especially in the twist direction of ribs on fruits, rows of bristles along each rib, rigidity, interweaving degree of bristles, and their geographical distribution. Therefore, it is suggested that C. pumilum and C. ruoqiangense should be considered as two independent species.
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Grazing exclusion-induced shifts, the relative importance of environmental filtering, biotic interactions and dispersal limitation in shaping desert steppe communities, northern China
Xing WANG, Naiping SONG, Xinguo YANG, Lei WANG, Lin CHEN
Journal of Arid Land    2018, 10 (3): 402-415.   DOI: 10.1007/s40333-018-0411-5
Abstract368)   HTML9)    PDF (400KB)(1180)      

Grazing exclusion is one of the most efficient approaches to restore degraded grassland but may negatively affects the recovery of species diversity. Changes in plant species diversity should be a consequence of the ecological assembly process. Local community assembly is influenced by environmental filtering, biotic interactions, and dispersal. However, how these factors potentially contribute to changes to species diversity is poorly understood, especially in harsh environments. In this study, two management siteswithin a Stipabrevifloradesert steppe community (typical natural steppe)were selected in northern China. In one of the two management sites, grazing has been excluded since 2010 and in the other with open grazing by sheep. In August 2016, three plots were established and 100 sampling units were created within each plot in a 5 m×5 m area at the two management sites.To assess the effects of grazing exclusion on S. breviflorasteppe, we analyzed the vegetation biomass, species diversity, soil organic carbon, and soil particle size distribution using pairedT-tests. In addition, variation partitioning was applied to determine the relative importance of environmental filtering and dispersal limitation. Null mode analysis was used to quantify the influence of biotic interactions in conjunction with EcoSim niche overlap and co-occurrence values. Our results demonstrated that (1) species diversity significantly decreased and the main improvements in soil quality occurred in the topsoil 0-10 cm after the grazing exclusion; (2) environmental filtering was important for community assembly between grazed and fenced grassland and this appears particularly true for soil particle size distribution, which may be well correlated with soil hydrological processes; and (3) however, competitive exclusion may play a significant role within the exclusion. The multiple pathways of assembly may collectively determine negative effects on the restoration of species diversity. Therefore, designers should be aware of the risk of reducing grazing exclusion-induced species diversity and account for manipulating processes.This in turn will reduce dominant species and promote environmental heterogeneity to maximize species diversity in semi-arid regions.

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Comparing phreatic evaporation at zero water table depth with water surface evaporation
Shunjun HU, Yongde GAN, Yongbao CHEN
Journal of Arid Land    2018, 10 (6): 968-976.   DOI: 10.1007/s40333-018-0108-9
Abstract289)   HTML4)    PDF (389KB)(707)      

Salt-affected soils are mostly found in irrigated areas within arid and semi-arid regions where the groundwater table is shallow. Soils of this type have become an increasingly severe problem because they threaten both the environment and the sustainable development of irrigated agriculture. A tool to estimate phreatic evaporation is therefore urgently required to minimize the salinization potential of salt-affected areas. In this context, phreatic evaporation at zero water table depth (E0) is a key parameter for establishing a model for calculating phreatic evaporation. The aim of this study was to explore the law of phreatic evaporation and to develop structurally rational empirical models for calculating phreatic evaporation, based on E0 data of six types of soil (i.e., gravel, fine sand, sandy loam, light loam, medium loam, and heavy loam) observed using the non-weighing lysimeter and water surface evaporation (E601) data observed using a E601 evaporator of same evaporation area with a lysimeter-tube at the groundwater balance station of the Weigan River Management Office in Xinjiang Uygur Autonomous Region, China, during the non-freezing period (April to October) between 1990 and 1994. The relationship between E0 and E601 was analyzed, the relationship between the ratio of E0 to E601 and the mechanical compositions of different soils was presented, and the factors influencing E0 were discussed. The results of this study reveal that E0 is not equal to E601. In fact, only values of the former for fine sand are close to those of the latter. Data also show that E0 values are related to soil texture as well as to potential atmospheric evaporation, the ratio of E0 to E601 and the silt-clay particle content (grain diameter less than 0.02 mm) is negatively exponentially correlated, and that soil thermal capacity plays a key role in phreatic evaporation at E0. The results of this analysis therefore imply that the treatment of zero phreatic depth is an essential requirement when constructing groundwater balance stations to study the law of phreatic evaporation.

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Effects of warming and clipping on plant and soil properties of an alpine meadow in the Qinghai-Tibetan Plateau, China
ManHou XU, Fei PENG, QuanGang YOU, Jian GUO, XiaFei TIAN, Min LIU, Xian XUE
Journal of Arid Land    2015, 7 (2): 189-204.   DOI: 10.1007/s40333-014-0010-z
Abstract1767)      PDF (457KB)(2158)      
Climate warming and livestock grazing are known to have great influences on alpine ecosystems like those of the Qinghai-Tibetan Plateau (QTP) in China. However, it is lacking of studies on the effects of warming and grazing on plant and soil properties in these alpine ecosystems. In this study, we reported the related research from manipulative experiment in 2010–2012 in the QTP. The aim of this study was to investigate the individual and com-bined effects of warming and clipping on plant and soil properties in the alpine meadow ecosystem. Infrared radia-tors were used to simulate climate warming starting in July 2010, while clipping was performed once in October 2011 to simulate the local livestock grazing. The experiment was designed as a randomized block consisting of five replications and four treatments: control (CK), warming (W), clipping (C) and warming+clipping combination (WC). The plant and soil properties were investigated in the growing season of the alpine meadow in 2012. The results showed that W and WC treatments significantly decreased relative humidity at 20-cm height above ground as well as significantly increases air temperature at the same height, surface temperature, and soil temperature at the depth of 0–30 cm. However, the C treatment did not significantly decrease soil moisture and soil temperature at the depth of 0–60 cm. Relative to CK, vegetation height and species number increased significantly in W and WC treatment, respectively, while vegetation aboveground biomass decreased significantly in C treatment in the early growing season. However, vegetation cover, species diversity, belowground biomass and soil properties at the depth of 0–30 cm did not differ significantly in W, C and WC treatments. Soil moisture increased at the depth of 40–100 cm in W and WC treatments, while belowground biomass, soil activated carbon, organic carbon and total nitrogen increased in the 30–50 cm soil layer in W, C and WC treatments. Although the initial responses of plant and soil properties to experimental warming and clipping were slow and weak, the drought induced by the down-ward shift of soil moisture in the upper soil layers may induce plant belowground biomass to transfer to the deeper soil layers. This movement would modify the distributions of soil activated carbon, organic carbon and total nitrogen. However, long-term data collection is needed to further explain this interesting phenomenon.
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Potato absorption and phytoavailability of Cd, Ni, Cu, Zn and Pb in sierozem soils amended with municipal sludge compost
Zheng LIU, Zhongren NAN, Chuanyan ZHAO, Yang YANG
Journal of Arid Land    2018, 10 (4): 638-652.   DOI: 10.1007/s40333-018-0062-6
Abstract382)   HTML3)    PDF (310KB)(933)      

Effects of sludge utilization on the mobility and phytoavailability of heavy metals in soil-plant systems have attracted broad attention in recent years. In this study, we analyzed the effects of municipal sludge compost (MSC) on the solubility and plant uptake of Cd, Ni, Cu, Zn and Pb in a soil-potato system to explore the mobility, potato plant uptake and enrichment of these five heavy metals in sierozem soils amended with MSC through a potato cultivation trial in Lanzhou University of China in 2014. Ridge regression analysis was conducted to investigate the phytoavailability of heavy metals in amended soils. Furthermore, CaCl2, CH3COONH4, CH3COOH, diethylene triamine pentacetic acid (DTPA) and ethylene diamine tetraacetic acid (EDTA) were used to extract the labile fraction of heavy metals from the amended soils. The results show that the MSC could not only improve the fertility but also increase the dissolved organic carbon (DOC) content of sierozem soils. The total concentrations and labile fraction proportions of heavy metals increase with increasing MSC percentage in sierozem soils. In amended soils, Cd has the highest solubility and mobility while Ni has the lowest solubility and mobility among the five heavy metals. The MSC increases the concentrations of heavy metals in the root, stem, peel and tuber of the potato plant, with the concentrations being much higher in the stem and root than in the peel and tuber. Among the five heavy metals, the bioconcentration factor value of Cd is the highest, while that of Ni is the lowest. The complexing agent (DTPA and EDTA) extractable fractions of heavy metals are the highest in terms of phytoavailability. Soil properties (including organic matter, pH and DOC) have important impacts on the phytoavailability of heavy metals. Our results suggest that in soil-potato systems, although the MSC may improve soil fertility, it can also increase the risk of soils exposed to heavy metals.

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Water adaptive traits of deep-rooted C 3 halophyte ( Karelinia caspica (Pall.) Less.) and shallow-rooted C4 halophyte ( Atriplex tatarica L.) in an arid region, Northwest China
Yuan FAN, PinFang LI, ZhenAn HOU, TuSheng REN, ChunLian XIONG, Biao ZHANG
Journal of Arid Land    2012, 4 (4): 469-478.   DOI: 10.3724/SP.J.1227.2012.00469
Abstract2971)      PDF (608KB)(2431)      
This paper focused on the water relations of two halophytes differing in photosynthetic pathway, phe-notype, and life cycle: Karelinia caspica (Pall.) Less. (C 3, deep-rooted perennial Asteraceae grass) and Atriplex tatarica L. (C 4, shallow-rooted annual Chenopodiaceae grass). Gas exchange, leaf water potential, and growth characteristics were investigated in two growing seasons in an arid area of Xinjiang to explore the physiological adaptability of the two halophytes. Both K. caspica and A. tatarica showed midday depression of transpiration, in-dicating that they were strong xerophytes and weak midday depression types. The roots of A. tatarica were con-centrated mainly in the 0–60 cm soil layer, and the leaf water potential ( YL )) increased sharply in the 0–20 cm layer due to high soil water content, suggesting that the upper soil was the main water source. On the other hand, K. caspica had a rooting depth of about 1.5 m and a larger root/shoot ratio, which confirmed that this species uptakes water mainly from deeper soil layer. Although A. tatarica had lower transpiration water consumption, higher water use efficiency (WUE), and less water demand at the same leaf water potential, it showed larger water stress impact than K. caspica, indicating that the growth of A. tatarica was restricted more than that of K. caspica when there was no rainfall recharge. As a shallow-rooted C 4 species, A. tatarica displayed lower stomatal conductance, which could to some extent reduce transpiration water loss and maintain leaf water potential steadily. In contrast, the deep-rooted C 3 species K. caspica had a larger root/shoot ratio that was in favor of exploiting groundwater. We concluded that C 3 species ( K. caspica) tapes water and C 4 species ( A. tatarica) reduces water loss to survive in the arid and saline conditions. The results provided a case for the phenotype theory of Schwinning and Ehleringer on halophytic plants.
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Endemics and endangered species in the biodiversity hotspot of the Shada Mountains, Saudi Arabia
THOMAS Jacob, A EL-SHEIKH Mohamed, A ALATAR Abdulrehman
Journal of Arid Land    2017, 9 (1): 109-121.   DOI: 10.1007/s40333-016-0025-8
Abstract835)   HTML2)    PDF (535KB)(1875)      

Shada Mountains in Saudi Arabia, separated by Maleel Wadi into twin mountains (i.e., Shada Alalah and Shada Asfal), are rich in biodiversity. We investigated the diversity of endemics and endangered species of the mountains based on the data collected from 38 stands falling in 8 elevational zones ranging from 500 to 2215 m a.s.l. Results indicated that 495 plant species falling in 314 genera and 76 families occurred in the Shada Mountains, including 19 endemic species and 43 endangered species, and accounting for 22% of the total flora in Saudi Arabia. Canonical correlation analysis indicated that physiographic features, particularly altitude play an important role in the frequency and abundance of species. Endemics were not evenly distributed in the Shada Mountains and mostly restricted in the elevation zone of 1000-1500 or >1500 m a.s.l. When the altitude reached up to 2000 m a.s.l., the endemics decreased substantially due to the significantly low temperature. The endangered species existed three different distribution patterns: (i) most endangered species distributed in the altitudes of 1000-1800 m a.s.l.; (ii) endangered trees, lianas, and shrubs occupied the altitudes 1000-1300 m a.s.l.; and (iii) endangered subshrubs and herbs inhabited the altitudes 1500-2100 m a.s.l. The results demonstrated that the biodiversity of endangered species in the Shada Mountains is high and undisturbed by invasive species, and protective measures should be taken against human disturbances to the small-scale hotspot.

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Identification of sand and dust storm source areas in Iran
CAO Hui, LIU Jian, WANG Guizhou, YANG Guang, LUO Lei
Journal of Arid Land    2015, 7 (5): 567-578.   DOI: 10.1007/s40333-015-0127-8
Abstract1593)      PDF (485KB)(4576)      
Sand and dust storms (SDS) are common phenomena in arid and semi-arid areas. In recent years, SDS frequencies and intensities have increased significantly in Iran. A research on SDS sources is important for understanding the mechanisms of dust generation and assessing its socio-economic and environmental impacts. In this paper, we developed a new approach to identify SDS source areas in Iran using a combination of nine related datasets, namely drought events, temperature, precipitation, location of sandy soils, SDS frequency, human-induced soil degradation (HISD), human influence index (HII), rain use efficiency (RUE) and net primary productivity (NPP) loss. To identify SDS source areas, we firstly normalized these datasets under uniform criteria including layer reprojection using Lambert conformal conic projection, data conversion from shapefile to raster, Min-Max Normalization with data range from 0 to 1, and data interpolation by Kriging and images resampling (resolution of 1 km). After that, a score map for the possibility of SDS sources was generated through overlaying multiple datasets under average weight allocation criterion, in which each item obtained weight equally. In the score map, the higher the score, the more possible a specific area could be regarded as SDS source area. Exceptions mostly came from large cities, like Tehran and Isfahan. As a result, final SDS source areas were mapped out, and Al-Howizeh/Al-Azim marshes and Sistan Basin were identified as main SDS source areas in Iran. The SDS source area in Al-Howizeh/Al-Azim marshes still keeps expanding. In addition, Al-Howizeh/Al-Azim marshes are now suffering rapid land degradation due to natural and human-induced factors and might totally vanish in the near future. Sistan Basin also demonstrates the impacts of soil degradation and wind erosion. With appropriate intensity, duration, wind speed and altitude of the dust storms, sand particles uplifting from this area might have developed into extreme dust storms, especially during the summer.
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Variability and divergence in horsegram (Dolichos uniflorus)
Kanaka K DURGA
Journal of Arid Land    2012, 4 (1): 71-76.   DOI: 10.3724/SP.J.1227.2012.00071
Abstract2697)      PDF (442KB)(3883)      
 Horsegram is an important and unexploited tropic and sub-tropic legume crop grown mostly in dry land agriculture. The study involving 23 cultivars of horsegram (Dolichos uniflorus) was conducted at the Seed Research & Technology Centre in Rajendranagar, Hyderabad, India during the early spring seasons of 2008 and 2009 to assess the nature and magnitude of variability in the existing species and also to identify diverse parents for use in further breeding programmes. The results indicated significant differences among the 23 cultivars for all characters studied, indicating the presence of sufficient genetic variation. High variability and heritability coupled with high genetic advance were reported for seed yield per plant and pod hulm per plant, indicating additive gene action and a possible scope for the improvement of these characters. Mahalanobis D2 statistics grouped all the 23 cultivars of horsegram into six clusters. The maximum inter cluster distance (62.39) was noticed between cluster IV (HG 50) and cluster V (HG 11). The maximum intra cluster distance ranged from 0 (clusters III, IV, V and VI) to 15.17 (cluster ?), indicating that the genotypes in these clusters were relatively more diverse than the genotypes within other clusters. Seed yield per plant contributed the maximum (33.20%) to the genetic divergence.
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A new ornithological record, Pechora Pipit Anthus gustavi Swinhoe, 1863, from Xinjiang
Peng DING, Ming MA, Ying CHEN, Geoff CAREY, Paul HOLT
Journal of Arid Land    2011, 3 (4): 300-302.   DOI: 10.3724/SP.J.1227.2011.00300
Abstract2843)      PDF (1084KB)(2404)      
On 15 September, 2010, a Pechora Pipit Anthus gustavi Swinhoe was found in the Hami prefecture (41°13′N and 93°29′E, 1,143 m a.s.l.), Xinjiang, during the period of a comprehensive scientific survey in Lop Nur region. The bird, which was photographed, is a new avian record for Xinjiang. The pipit reproduces in northern Eurasia, mainly in wide meadows and low hills, and can be found in open forests and nearby residential areas in the process of on migration. The species is an insectivore and is a rare migrant or vagrant in Xinjiang. The geographical distribution, character, habitat, ecological habit and subspecies of the Pechora Pipit were discussed in this paper.
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Impact factors of soil wind erosion in the center of Taklimakan Desert
Qing HE, XingHua YANG, Ali Mamtimin, ShiHao TANG
Journal of Arid Land    DOI: 10.3724/SP.J.1227.2011.00009
Abstract3647)      PDF (239KB)(5471)      
The development and progress of soil wind erosion are influenced by the factors of climate, terrain, soil and vegetation, etc. This paper, taking Tazhong region, a town in the centre of the Taklimakan Desert, as an example and using comparative and quantitative methods, discussed the effects of climate, surface roughness (including vegetation cover) and surface soil properties on soil wind erosion. The results showed that the climate factor index C of annual wind erosion is 28.3, while the maximum of C is 13.9 in summer and it is only 0.7 in winter. The value of C has a very good exponential relationship with the wind speed. In Tazhong region, the surface roughness height is relatively small with a mean of 6.32 × 10-5 m, which is in favor of soil wind erosion. The wind erosion is further enhanced by its sandy soil types, soil particle size, lacking of vegetation and low soil moisture content. The present situation of soil wind erosion is the result of concurrent effects of climate, vegetation and surface soil properties.
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Ecophysiological aspects in 105 plants species of saline and arid environments in Tunisia
Abdallah ATIA, Mokded RABHI, Ahmed DEBEZ, Chedly ABDELLY, Houda GOUIA, Chiraz CHAFFEI HAOUARI, Abderrazak SMAOUI
Journal of Arid Land    2014, 6 (6): 762-770.   DOI: 10.1007/s40333-014-0028-2
Abstract1600)      PDF (297KB)(2936)      
In Tunisian arid regions, plant life forms, ecotypes, physiological types and photosynthetic pathways (C 3, C 4 or CAM) remain unclear. Understanding the characters of these plant species could be important for land restoration. A literature survey was conducted for 105 species from arid regions of Tunisia. These plant species belong to several eco-types: halophytes, xerophytes, gypsophytes, psamophytes, xero-halophytes, gypso-halophytes, psamo-halophytes, psamo-xerophytes, xero-gypsophytes and hygro-halophytes. The variation of photosynthetic pathway types in the 105 studied species shows that 56.2% are C 3, 41.0% are C 4, 1.9% are CAM and 1.0% are C 3-CAM. The C 3 pathway is more abundant in the halophytes, whereas the C4 one is more common in the xerophytes, gypsophytes, gypso-halophytes and psamo-halophytes. The ratio of C 3 to C 4 species (C 3/C 4 ratio) is 0.2 in the psamo-halophytes, 0.8 in the gypso-halophytes, 1.1 in the xerophytes, 1.6 in the xero-halophytes, 1.8 in the hygrohalophytes, 2.0 in the psamophytes and 3.8 in the halophytes. The annuals are mainly C 3 plants whereas most of perennials are C 4 ones. The C 3/C 4 ratio is 1.3 in succulent species and 1.4 in non-succulent species. Thus, succulence seems not to affect the distribution of C 3 and C 4 pathways within the studied plants.  This investigation shows high percentages of C 4 plants in plants of Tunisian arid regions. However, there are significant differences in their abundance among ecotypes. Based on C 3/C4 ratio, the abundance of the C 4 pathway is in the following order: psamo-halophytes, gypso-halophytes, xerophytes, xero-halophytes, hy-grohalophytes, psamophytes, halophytes. In Tunisian arid regions, C 4 species are most abundant in xerophytes and less abundant in halophytes. In the Chenopodiaceae the number of C 3 plants is 13 and the number of C 4 species is 20 and in the Poaceae the number of C 3 was 23 and the number of C 4 was 19 species. Thus, the most C4 proportion is in the Chenopodiaceae and Poaceae species. This confirms the fact that the Chenopodiaceae and the Poaceae were the leading families that tolerate salinity and aridity.
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Rangelands of Central Asia: challenges and opportunities
Alisher MIRZABAEV, Mohamed AHMED, Jutta WERNER, John PENDER, Mounir LOUHAICHI
Journal of Arid Land    2016, 8 (1): 93-108.   DOI: 10.1007/s40333-015-0057-5
Abstract1398)      PDF (258KB)(2031)      
Rangelands of Central Asia (referring to Kazakhstan, Kyrgyzstan, Tajikistan, Turkmenistan and Uzbekistan in this study), the largest contiguous area of grazed land in the world, serve as an important source of livelihood for pastoral and agro-pastoral communities in this region. They also play an important role in absorbing CO 2 as a global carbon sink. However, unsustainable management of rangelands has led to their degradation hugely by downgrading their potential agro-ecological, environmental and socio-economical roles. This paper reviewed the rangeland degradation in Central Asia, a topic which so far has received only scant coverage in the international scientific literature. It also provided examples of successful experiences and outlined possible options that land managers can adopt to enhance the sustainable management of these vast degraded rangelands. The experiences and lessons described in this paper may also be relevant for other degraded rangeland areas, especially in the developing countries. The causes of rangeland degradation within the Central Asian region are numerous, complex and inter-related. Therefore, while addressing the factors associated with improper rangeland management may shed some light on the causes of rangeland degradation, the scope of this paper would not be all-encompassing for the major causes of degradation. There is a need to develop and widely apply the viable and locally accepted and adapted packages of technical, institutional and policy options for sustainable rangeland management. Incentivizing the collective action of small-scale pastoralists who group together to facilitate access to remote pastures can reduce the degree of overgrazing within community pastures, such as those near the settlements. We also found that migratory grazing through pooling of resources among small-scale pastoralists can increase household income. After their independence, most Central Asian countries adopted various rangeland tenure arrangements. However, the building of enhanced capacities of pasture management and effective local rangeland governance structures can increase the likelihood, which will be sustainable and equitable. Finally, this paper presented several promising technical options, aiming at reversing the trend of rangeland degradation in Central Asia.
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Environmental factors influencing snowfall and snowfall prediction in the Tianshan Mountains, Northwest China
Xueting ZHANG, Xuemei LI, Lanhai LI, Shan ZHANG, Qirui QIN
Journal of Arid Land    2019, 11 (1): 15-28.   DOI: 10.1007/s40333-018-0110-2
Abstract403)   HTML7)    PDF (484KB)(1019)      

Snowfall is one of the dominant water resources in the mountainous regions and is closely related to the development of the local ecosystem and economy. Snowfall predication plays a critical role in understanding hydrological processes and forecasting natural disasters in the Tianshan Mountains, where meteorological stations are limited. Based on climatic, geographical and topographic variables at 27 meteorological stations during the cold season (October to April) from 1980 to 2015 in the Tianshan Mountains located in Xinjiang of Northwest China, we explored the potential influence of these variables on snowfall and predicted snowfall using two methods: multiple linear regression (MLR) model (a conventional measuring method) and random forest (RF) model (a non-parametric and non-linear machine learning algorithm). We identified the primary influencing factors of snowfall by ranking the importance of eight selected predictor variables based on the relative contribution of each variable in the two models. Model simulations were compared using different performance indices and the results showed that the RF model performed better than the MLR model, with a much higher R2 value (R2=0.74; R2, coefficient of determination) and a lower bias error (RSR=0.51; RSR, the ratio of root mean square error to standard deviation of observed dataset). This indicates that the non-linear trend is more applicable for explaining the relationship between the selected predictor variables and snowfall. Relative humidity, temperature and longitude were identified as three of the most important variables influencing snowfall and snowfall prediction in both models, while elevation, aspect and latitude were of secondary importance, followed by slope and wind speed. These results will be beneficial to understand hydrological modeling and improve management and prediction of water resources in the Tianshan Mountains.

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Performance of different drought indices for agriculture drought in the North China Plain
Xianfeng LIU, Xiufang ZHU, Yaozhong PAN, Jianjun BAI, Shuangshuang LI
Journal of Arid Land    2018, 10 (4): 507-516.   DOI: 10.1007/s40333-018-0005-2
Abstract500)   HTML12)    PDF (400KB)(1595)      

The Palmer drought severity index (PDSI), standardized precipitation index (SPI), and standardized precipitation evapotranspiration index (SPEI) are used worldwide for drought assessment and monitoring. However, substantial differences exist in the performance for agricultural drought among these indices and among regions. Here, we performed statistical assessments to compare the strengths of different drought indices for agricultural drought in the North China Plain. Small differences were detected in the comparative performances of SPI and SPEI that were smaller at the long-term scale than those at the short-term scale. The correlation between SPI/SPEI and PDSI considerably increased from 1- to 12-month lags, and a slight decreasing trend was exhibited during 12- and 24-month lags, indicating a 12-month scale in the PDSI, whereas the SPI was strongly correlated with the SPEI at 1- to 24-month lags. Interestingly, the correlation between the trend of temperature and the mean absolute error and its correlation coefficient both suggested stronger relationships between SPI and the SPEI in areas of rapid climate warming. In addition, the yield-drought correlations tended to be higher for the SPI and SPEI than that for the PDSI at the station scale, whereas small differences were detected between the SPI and SPEI in the performance on agricultural systems. However, large differences in the influence of drought conditions on the yields of winter wheat and summer maize were evident among various indices during the crop-growing season. Our findings suggested that multi-indices in drought monitoring are needed in order to acquire robust conclusions.

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Saline dust storms and their ecological impacts in arid regions
Jilili Abuduwaili, DongWei LIU, GuangYang WU
Journal of Arid Land    DOI: 10.3724/SP.J.1227.2010.00144
Abstract3339)      PDF (210KB)(3893)      
In many arid and semiarid regions, saline playas represent a significant source of unconsolidated sediments available for aeolian transport, and severe saline dust storms occur frequently due to human disturbance. In this study, saline dust storms are reviewed systematically from the aspects of concept, general characteristics, conditions of occurrence, distribution and ecological impact. Our researches showed that saline dust storms are a kind of chemical dust storm originating in dry lake beds in arid and semiarid regions; large areas of unconsolidated saline playa sediments and frequent strong winds are the basic factors to saline dust storm occurrence; there are differentiation characteristics in deposition flux and chemical composition with wind-blown distance during saline dust storm diffusion; and saline dust storm diffusion to some extent increases glacier melt and results in soil salinization in arid regions. An understanding of saline dust storms is important to guide disaster prevention and ecological rehabilitation.
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Distribution of soil aggregates and organic carbon in deep soil under long-term conservation tillage with residual retention in dryland
Bisheng WANG, Lili GAO, Weishui YU, Xueqin WEI, Jing LI, Shengping LI, Xiaojun SONG, Guopeng LIANG, Dianxiong CAI, Xueping WU
Journal of Arid Land    2019, 11 (2): 241-254.   DOI: 10.1007/s40333-019-0094-6
Abstract245)   HTML5)    PDF (389KB)(704)      

To ascertain the effects of long-term conservation tillage and residue retention on soil organic carbon (SOC) content and aggregate distribution in a deep soil (>20-cm depth) in a dryland environment, this paper analyzed the SOC and aggregate distribution in soil, and the aggregate-associated organic carbon (OC) and SOC physical fractions. Conservation tillage (reduced tillage with residue incorporated (RT) and no-tillage with residue mulch (NT)) significantly increased SOC sequestration and soil aggregation in deep soil compared with conventional tillage with residue removal (CT). Compared with CT, RT significantly increased the proportion of small macroaggregates by 23%-81% in the 10-80 cm layer, and the OC content in small macroaggregates by 1%-58% in the 0-80 cm layer. RT significantly increased (by 24%-90%) the OC content in mineral-SOC within small macroaggregates in the 0-60 cm layer, while there was a 23%-80% increase in the 0-40 cm layer with NT. These results indicated that: (1) conservation tillage treatments are beneficial for soil aggregation and SOC sequestration in a deep soil in a dryland environment; and (2) the SOC in mineral-associated OC plays important roles in soil aggregation and SOC sequestration. In conclusion, RT with NT is recommended as an agricultural management tool in dryland soils because of its role in improving soil aggregation and SOC sequestration.

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Status and distribution of ungulates in Xinjiang, China
XingYi GAO, WenXuan XU, WeiKang YANG, David A BLANK, JianFang QIAO, KeFen XU
Journal of Arid Land    DOI: 10.3724/SP.J.1227.2011.00049
Abstract2778)      PDF (205KB)(2690)      
Based on a long-term field investigation and other research results, we reviewed the status and distribution of ungulates in Xinjiang, China. The ungulates in Xinjiang included 19 ungulate species (30 subspecies) from 6 families and 2 orders. Among them, 3 species (2 subspecies) relate to Equidae (Perrisodactyla), and 16 species (28 subspecies) are from 5 families of Artiodactyla. In this paper, we analyzed the conservation status of most rare and important 13 ungulate species. Firstly, we proposed the protection of genetic diversity of Camelus ferus and the distribution areas of Moschus sifanicus, Procapra przewalskii and Saiga tatarica in Xinjiang. We found that Moschus sifanicus but not Procapra przewalskii distributed in Xinjiang. It was not clear whether the remnant populations of Saiga tatarica existed in Xinjiang and China-Kazakhstan border or not. We discussed that the protection level and rational use of Capra sibirica and enhancing protection level and enlarging monitoring and research projects for Pantholops hodgsoni and Gazella subgutturosa. And we would like to suggest Forestry Department to develop the captive breeding of Tibetan antelope for rational use. In addition, the captive breeding of Cervus elaphus in Xinjiang was reviewed. Local government should lessen strong control to Cervus elaphus because of many breeding centers’ establishment.
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Model based decision support system for land use changes and socio-economic assessments
Yang YU, Xi CHEN, HUTTNER Philipp, HINNENTHAL Marie, BRIEDEN Andreas, Lingxiao SUN, DISSE Markus
Journal of Arid Land    2018, 10 (2): 169-182.   DOI: 10.1007/s40333-018-0091-1
Abstract426)   HTML31)    PDF (939KB)(840)      

Hydrological models are often linked with other models in cognate sciences to understand the interactions among climate, earth, water, ecosystem, and human society. This paper presents the development and implementation of a decision support system (DSS) that links the outputs of hydrological models with real-time decision making on social-economic assessments and land use management. Discharge and glacier geometry changes were simulated with hydrological model,water availability in semi-arid environments. Irrigation and ecological water were simulated by a new commercial software MIKE HYDRO. Groundwater was simulated by MODFLOW. All the outputs of theses hydrological models were taken as inputs into the DSS in three types of links: regression equations, stationary data inputs, or dynamic data inputs as the models running parallel in the simulation periods. The DSS integrates the hydrological data, geographic data, social and economic statistical data, and establishes the relationships with equations, conditional statements and fuzzy logics. The programming is realized in C++. The DSS has four remarkable features: (1) editable land use maps to assist decision-making; (2) conjunctive use of surface and groundwater resources; (3) interactions among water, earth, ecosystem, and humans; and (4) links with hydrological models. The overall goal of the DSS is to combine the outputs of scientific models, knowledge of experts, and perspectives of stakeholders, into a computer-based system, which allows sustainability impact assessment within regional planning; and to understand ecosystem services and integrate them into land and water management.

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Effects of mulches on water use in a winter wheat/summer maize rotation systemin Loess Plateau, China
Minhua YIN, Yuannong LI, Yuanbo XU, Changming ZHOU
Journal of Arid Land    2018, 10 (2): 277-291.   DOI: 10.1007/s40333-018-0092-0
Abstract390)   HTML13)    PDF (477KB)(1076)      

Limited water resources often result in reducedcrop yield and low water productivity(WP). In northwestern China, crop production is generally dependent on precipitation. Therefore, a variety of agricultural rainwaterharvesting (ARH) techniques have been used for conserving soil moisture, ameliorating soil environment, increasing crop yield, and improving water use efficiency. A two-year (2013-2015) field experiment was conducted under a typical sub-humid drought-prone climate in Yangling (108°24′E, 34°20′N; 521 m a.s.l.), Shaanxi Province, China, to explore the effects of mulching(same for summer maize and winter wheat) on soil moisture, soil temperature, crop water consumption, and crop yield with a winter wheat/summer maize rotation. Crops were planted in a ridge-furrow pattern and the treatments consisted of a transparent film mulch over the ridges (M1), a crop straw mulch in the furrows (M2), a transparent film mulch over the ridges and a crop straw mulch in the furrows (M3), a black film mulch over the ridges and a crop straw mulch in the furrows (M4), and a control with no mulch (CK). Results showed that M4 was the best treatment for improving soil water storage and content, and decreasing crop water consumption during the summer maize and winter wheat rotation.In both maize and wheat seasons, M1 had a higher soil temperature than M2 and CK, and M3 had a higher soil temperature than M4. In the maize seasons, M4 had the highest yield, WP, and precipitation productivity (PP), with the average values for these parameters increasing by 30.9%, 39.0%, and 31.0%, respectively, compared to those in CK. In the wheat seasons, however, M3 had the highest yield, WP, and PP, with the average values for these parameters being 23.7%, 26.7%, and 23.8% higher, respectively, than those in CK. Annual yield (maize and wheat yields combined) and WP did not differ significantly between M3 and M4. These results suggested that M3 and M4 may thus be the optimal ARH practices for the production of winter wheat and summer maize, respectively, in arid and semi-arid areas.

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