Table of Content

15 January 2021, Volume 38 Issue 1 Previous Issue    Next Issue

Pan-Third Pole Environment and Green Silk Road

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Analysis of climate characteristics in the Pan-Central-Asia arid region YAN Xinyang,ZHANG Qiang,ZHANG Wenbo,REN Xueyuan,WANG Sheng,ZHAO Funian 2021, 38 (1):  1-11.  doi: 10.13866/j.azr.2021.01.01 Abstract ( 835 )   HTML ( 51 )   PDF (4095KB) ( 572 )   Climate change in arid areas is an important scientific issue. Based on monthly Climatic Research Unit data from 1949 to 2018, the characteristics of climate change in the Pan-Central-Asian arid region throughout the past 70 years were studied used empirical orthogonal function (EOF) and wavelet analyses. The results showed that precipitation in the Pan-Central-Asian arid area increased at the rate of 1.393 mm·(10a)-1 in the past 70 years. Precipitation in summer showed a decreasing trend, while the other three seasons showed an increasing trend, of which winter was the most obvious [0.834 mm·(10a)-1]. Winter also showed the largest temperature increase [0.360 °C·(10a)-1]. EOF analysis of precipitation anomalies shows that the precipitation anomalies in the Pan-Central-Asia arid region reflected overall consistency (the first mode of precipitation), the southwest-northeast showed reverse change characteristics (the second mode of precipitation), and west to east exhibited “-+-” alternating distribution characteristics (the third mode of precipitation). There were markedly quasi 3 a periods in all three modes, and the first mode also had quasi 5-7 a and quasi 12 a periods, while the third mode also exhibited a quasi 7 a change period. The EOF analysis of temperature anomalies showed that the temperature anomalies reflected the overall consistency (the first mode of temperature), east-west showed reverse change characteristics (the second mode of temperature), and the first mode had quasi 2 a and 8-10 a periods. At the same time, there were obvious 2-4 a and quasi 5 a cycles in the second mode. The warm season did not show a more obvious increase in the temperature and rainfall, while the cold season showed a larger increase in temperature and precipitation. Some regions presented a witting trend, such as the east and west sides of Kazakhstan, northern Xinjiang in China, and parts of the Pamir Plateau, while other places like central Kazakhstan, most of Mongolia, and Northwestern China exhibited an obvious drying trend. In general, most of Northwest China is in a weak wetting trend. With the weakening of the Asian summer monsoon, the precipitation increment in the cold season is higher than that in the warm season, which seems to indicate that the influence of the Asian winter monsoon on precipitation in the Pan-Central-Asia arid area is increasing. The research results of this paper aim to deepen the understanding of the characteristics of climate change in the Pan-Central-Asia arid region, as well as provide a scientific basis for further disaster prevention and mitigation, rational response to climate change, and sustainable development strategies. Figures and Tables | References | Related Articles | Metrics

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Bias analysis and applicability evaluation of the atmospheric infrared sounder (AIRS) radiance in Central Asia MA Yufen,LI Ruqi,ZHANG Meng,Ali Mamtimin,ZHANG Guangxing 2021, 38 (1):  12-21.  doi: 10.13866/j.azr.2021.01.02 Abstract ( 355 )   HTML ( 13 )   PDF (4448KB) ( 284 )   Due to a scarcity of observation sites, only a small amount of conventional observation data on the temporal and spatial distribution of temperature and humidity in Central Asia can be obtained, which makes analysis difficult. High-resolution air infrared detector (AIRS) data can effectively fill the gap. In this paper, the radiance temperature of AIRS simulated by the input radiosonde in the Community Radiative Transfer Model was utilized as the reference value, deviations in the brightness temperature of the AIRS observation were analyzed, and the applicability of AIRS satellite data in the Central Asia numerical weather forecast operation system was evaluated. First, it shows that the average value of the maximum positive deviation of brightness temperature over the selected stations was approximately 3.3 K, and the absolute value of the maximum negative deviation was approximately 2.6 K. Second, the average brightness temperature of the AIRS observation in multiple stations was slightly higher than the overall simulated brightness temperature, and its probability density distribution was closer to the normal distribution curve than that of a single station. Finally, the assimilation of AIRS improved the prediction effect of RMAPS-CA on the geopotential height, temperature, specific humidity, and other high-altitude elements, but did not improve the prediction of high-altitude wind speed. For each factor, the assimilation improvement range of AIRS was larger at the lower and higher levels. After assimilation, the root mean square error of the geopotential height, temperature, specific humidity, and wind speed were less than 20 gpm, 2 K, 8×10-4 kg·kg-1 and 5 m·s-1, respectively. It should be noted that, due to the time limitations imposed on the encrypted sounding experiment, only one full month in July 2016 was selected as the research time period in the deviation analysis of this study. Due to the relatively less vegetation coverage on the underlying surface in Central Asia, the surface radiation was large in summer, while the area without snow cover in winter was relatively small. Therefore, the conclusion of the deviation analysis in this paper is not necessarily applicable to other seasons. In addition, considering the possibility of a business transformation of the research results, this study was based on Rapid-Refresh Multiscale Analysis and Prediction System-Central Asia (RMAPS-CA) to carry out assimilation analysis when evaluating the applicability of AIRS. The system uses the three-dimensional variational data assimilation (3DVAR) method. If a more advanced four-dimensional variational data assimilation (4DVAR) assimilation method is adopted, the assimilation effect may improve. Figures and Tables | References | Related Articles | Metrics

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Analysis of precipitation change and its contribution in the rainy season in the northeast Qinghai-Tibet Plateau from 1961 to 2017 YANG Zhaoming,ZHANG Tiaofeng 2021, 38 (1):  22-28.  doi: 10.13866/j.azr.2021.01.03 Abstract ( 670 )   HTML ( 20 )   PDF (5551KB) ( 475 )   The study on the characteristics of precipitation in the Qinghai-Tibet Plateau under the background of climate warming is of great significance for revealing the impact of climate change on agriculture, animal husbandry, and ecological environment. Based on the daily precipitation data of 53 meteorological observation stations from May to September of 1961-2017, the characteristics of rainy season precipitation in the northeast Qinghai-Tibet Plateau and the relative contribution of changes in precipitation of different grades in precipitation increment were analyzed. The results showed that the rainy season precipitation in the arid region in the northeast of the Qinghai-Tibet Plateau increased and that in the semi-arid and semi-humid regions became extreme from 1961 to 2017. Precipitation intensity has generally increased in most areas. Further analysis showed that the change in rainy season precipitation in the northeast of the Qinghai-Tibet Plateau is caused by the change in precipitation intensity, and the increase in contribution of moderate rainfall grade precipitation is greater than that of other grade precipitation. The trend of precipitation extremization in the east of the semi-humid and semi-arid regions was obviously enhanced. The results are helpful in understanding the climatic effect of change in ecological environment on the northeast of Qinghai-Tibet Plateau. Figures and Tables | References | Related Articles | Metrics

Water Resources and Utilization

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Flow regime alterations of upper Heihe River based on improved RVA ZHANG Ruqiang,LIU Junguo,MAO Ganquan,WANG Li 2021, 38 (1):  29-38.  doi: 10.13866/j.azr.2021.01.04 Abstract ( 486 )   HTML ( 11 )   PDF (5003KB) ( 278 )   Objective evaluation of flow regime alteration is the foundation of river ecological restoration and integrated water resources management. Various approaches that take hydrological year types into consideration could objectively evaluate the altered flow regime. Due to climate change in the recent decades, the flow regime of upper Heihe River has altered and needs further research. Our study area was the upper Heihe River, where we employed an improved range of variability approaches to analyze the alterations of the flow regime. Firstly, we applied the Mann-Kendall method to identify the catastrophe point. We analyzed the flow regime using hydrological alteration indicator method. This method includes 33 parameters classified into five groups: The magnitude of monthly water conditions, magnitude and duration of annual extreme water conditions, timing of annual extreme water conditions, frequency and duration of high and low pulses, and rate and frequency of water condition changes. Based on these groups, we used the range variability approach to calculate the degree of alteration of these 33 parameters. We measured the difference in typical hydrologic years before and after the catastrophe point using the Euclidean distance. The degree of hydrologic alteration was calculated considering the alteration of these 33 parameters and the difference between typical hydrologic years. Our results indicated that the year 2002 was catastrophic point of the river flow regime. The main hydrological type years before and after 2002 were normal flow and wet years. The improved method calculated an alteration degree of 74.62%, while the range of variability approach showed an alteration of 54.68%, indicating underestimation of the effect. Compared to 1960-2002, the monthly mean streamflow in 2003-2015 increased to various extents in the upper Heihe River’s flow regime. The annual minima 1 day, 3 day, 7 day, and annual maxima 7 day decreased, whereas the other extreme water condition indicators increased. The frequency and duration of high and low pulses changed slightly, and the average peak flow duration decreased while the other indicators increased. Rate and frequency of water condition increased. The degree of hydrologic alteration was 74.62% considering the change of HYTs, which indicated a high alteration in the upper Heihe River’s flow regime. Climate change is the main reason causing the flow regime alteration. Figures and Tables | References | Related Articles | Metrics

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Evaluation of ecological water security and analysis of driving factors in the lower Tarim River, China LI Mengyi,DENG Mingjiang,LING Hongbo,WANG Guangyan,XU Shengwu 2021, 38 (1):  39-47.  doi: 10.13866/j.azr.2021.01.05 Abstract ( 484 )   HTML ( 14 )   PDF (3502KB) ( 365 )   Due to the continuous strengthening of the unified water resource management programs in the Tarim River Basin, the ecological water transport in its lower reaches has increased, and periodic improvements in ecological protection have been achieved. However, there is a lack of scientific evaluation regarding the impact of strict water resource management program on the water ecological security status and changes. This study used principal component analysis and comprehensive coefficient method to evaluate the water ecological security status and reveal the changing characteristics of the driving factors affecting it. The analyses were based on the 2000 to 2017 index data of water quantity, groundwater depth of the monitored section, new Populus euphratica biomass, vegetation coverage, and drought indices in the lower reaches of the Tarim River. The results showed that from 2000 to 2017 the comprehensive water ecological security evaluation index increased from 39.1 to 84.7, and the ecological security level continuously improved, changing the area from a “moderate warning” to a “safe” area. Hydrological and vegetative influences are the two driving factors affecting downstream water ecological security; therefore, the volume of discharge, groundwater depth, and vegetation diversity significantly impact water ecological security. This study could provide an important scientific basis for optimizing the ecological water transport model in the lower reaches of the Tarim River. Figures and Tables | References | Related Articles | Metrics

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Analysis of the change in water level and its influencing factors on Bosten Lake from 1960 to 2018 LI Yujiao,CHEN Yaning,ZHANG Qifei,FANG Gonghuan 2021, 38 (1):  48-58.  doi: 10.13866/j.azr.2021.01.06 Abstract ( 2540 )   HTML ( 67 )   PDF (4490KB) ( 419 )   Using measurements of the water level and runoff into the lake as well as data from meteorological stations of Bosten Lake from 1960 to 2018, this paper provides a detailed analysis of the trend in water level change based on ensemble empirical mode decompsition and the water balance model. In addition, this paper uses the climate elasticity method to explore the response of the water level to hydroclimatic factors in different time periods, and then analyzes the complex response of the lake water level to climate change and human activities. The results revealed the following: (1) The lake level shows a significant decreasing trend from 1960 to 2018, which is shown in the four periods as “descending-rising-descending-rising”. (2) Ensemble empirical mode decomposition analysis results show that the water level of Bosten Lake has periodic oscillations of 3-4 a and 8-9 a on the interannual scale, and 29-30 a and 33-34 a on the interdecadal scale. (3) The contributions of precipitation, temperature, and potential evapotranspiration to runoff to the Kaidu River, Huangshui River, and Yanqi Basin from 1960 to 2018 were approximately 85.1%, 42.1%, and 23.8%, respectively. Other factors contributed approximately 14.9%, 57.9%, and 76.2% to the runoff. (4) The prime reason for the decline in water level in Bosten Lake from 1960 to 1987 was the decrease in runoff into the lake and substantial evaporation of the lake surface. Increase in lake water intake due to the climate change was the main cause of rise in water level from 1988 to 2002. The decrease in runoff into the lake and increase in the amount of lake water are responsible factors for the decreased water level from 2003 to 2014. An increase in lake water intake and strict controls on discharge from 2015 to 2018 were the major reasons for the rising water level in Bosten Lake. Figures and Tables | References | Related Articles | Metrics

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Estimation of groundwater evapotranspiration with measured diurnal groundwater variations: A case study of typical oasis in Hexi Corridor WANG Jingjing,LIU Hu,XU Zongxue,WANG Sijia 2021, 38 (1):  59-67.  doi: 10.13866/j.azr.2021.01.07 Abstract ( 475 )   HTML ( 10 )   PDF (3749KB) ( 345 )   Daily groundwater evapotranspiration (ETg) was estimated for the shallow groundwater area of the new oasis in the middle reaches of the Heihe River basin using diurnal water level fluctuation methods （White, Hays, Loheide）. The results were compared with the potential evapotranspiration (PET) estimated using Penman method, water surface evaporation (ET0) measured using E-601 pan, and water surface evaporation (ET1) measured using Φ20, and the differences between ETg and PET (ET0 and ET1) were analyzed using Pearson correlation coefficient. The results showed that among these calculation methods, Hays method performed the best with the highest accuracy, followed by the White method, and the Loheide method performed the worst with the lowest accuracy. Therefore, Hays method is recommended for estimation of daily ETg and ET0 is recommended for testing the estimation accuracy. Loheide method showed high ETg accuracy (R=0.821, P<0.01) with approximate 3 hr time lag, which was also found in other areas of the Heihe River basin (old oasis, desert edge, shelterbelt). The results obtained in this study will be helpful and may offer scientific support for rational allocation, sustainable development, and utilization of regional water resources in the Heihe River basin. Figures and Tables | References | Related Articles | Metrics

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Hydrochemical characteristics and cause analysis of the shallow groundwater in Shihezi City ZENG Xiaoxian,ZENG Yanyan,ZHOU Jinlong,LEI Mi,SUN Ying 2021, 38 (1):  68-75.  doi: 10.13866/j.azr.2021.01.08 Abstract ( 575 )   HTML ( 14 )   PDF (4818KB) ( 370 )   We studied the groundwater hydrochemical characteristics from the Shihezi City, Xinjiang. We used descriptive statistics and trilinear diagrams of Piper to analyze the main groundwater chemical contents and hydrochemical types of 19 phreatic groundwater and 25 shallows confined to groundwater samples. We used Schoeller diagram, Gibbs diagram and ion ratio diagram to analyze the causes of groundwater chemical characteristics formation. The shallow groundwater had weak alkaline water with low salinity, and the total groundwater hardness was 68.4%. The groundwater total dissolved solids were 97.7% in fresh groundwater. The main cations were Ca2+ and Na++K+, and the main anions were HCO3- and SO42-. The groundwater recharge sources were different in space, and ions might migrate from relatively high concentration points to relatively low concentration points along the groundwater flow direction. The primary groundwater hydrochemical types were HCO3-Ca and HCO3·SO4-Ca, followed by HCO3·SO4-Na. The Gibbs diagram results showed that the phreatic groundwater was mainly affected by both rock weathering and infiltration recharge after evaporation-concentration of surface water, while shallow confined groundwater was affected primarily by rock weathering. The saturation index method and ion ratio diagram indicated that the main ions in groundwater originated from the dissolution of evaporite. The dissolution of halite was the primary source of K+ and Na+ in groundwater, and the dissolution of evaporite or calcium magnesium silicate was the main source of Ca2+ and Mg2+. There was a negative correlation between γ(Na+-Cl-) and γ(Ca2++Mg2+)-γ(HCO3- + SO42-), indicated that cation exchange also played an essential role in the hydrochemical formation of shallow groundwater. Shihezi City is a typical oasis city in the Northwest arid region. Our results revealed the formation mechanism of shallow groundwater and provided a scientific basis for the rational development and utilization of shallow groundwater and water treatment. Figures and Tables | References | Related Articles | Metrics

Soil Resources

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Variation of soil moisture content in vegetation restoration area of sandy land at east shore of Qinghai Lake WANG Haijiao,TIAN Lihui,ZHANG Dengshan,WANG Qiaoyu 2021, 38 (1):  76-86.  doi: 10.13866/j.azr.2021.01.09 Abstract ( 590 )   HTML ( 9 )   PDF (4646KB) ( 219 )   Spatial-temporal heterogeneity of soil moisture is the main driving force for variation of vegetation patterns and processes in the desert, directly affecting plant growth in arid and semi-arid regions. Here, we used the dunes of planted sand-fixing plants (Populus sylvestris, Pinus sylvestris, Hippophae rhamnoides, and Salix cheilophila) at the eastern sandy shore of Qinghai Lake as study site and compared them to natural fixed dunes dominated by Artemisia ordosica. Our objectives were to analyze how soil’s moisture and geomorphological features influence the plants’ distribution in alpine semi-arid sandy lands. Our results showed that: (1) Precipitation, vegetation transpiration, soil’s surface evaporation were the main environmental features affecting soil’s seasonal moisture content, that varied among species, but that was the highest in July; (2) Depending on the dune’s position, soil moisture content might be different, even for the same species: Populus simonii had the most increased soil’s moisture content windward, while P. sylvestris, H. rhamnoides, and S. cheilophila had the most increased soil’s moisture content when leeward, and A. ordosica had the highest soil’s moisture content at dune’s top. However, geomorphology only played a significant difference in soil’s moisture content for S. cheilophila (P<0.05). Soil’s water content for different species in the same position was also different: At the windward, soil’s water content for P. sylvestris was 1. 81% and that of A. ordosica was 3.48%. At the dune’s top, the soil’s water content for S. cheilophila was 1. 82%, while that for A. ordosica was 3.58%. There was no significant difference in soil’s moisture content among species at the leeward, but that for S. cheilophila was 3.41%; (3) Soil’s moisture varied with depth and was the highest at 10-20 cm. The soil’s moisture vertical distribution also varied according to the plant species: it increased with depth with P. simonii and H. rhamnoides, while it gradually decreased with increasing soil depth for the other species. The soil’s water content decreased with soil’s depth for P. sylvestris and P. sylvestris, while it showed no noticeable change with H. rhamnoides and A. sylvestris up to 120 cm in depth. A varying soil’s water content was observed with S. cheilophila in different geomorphological positions and soil layers, which showed that no obvious change on the windward, lowering of the chest and increasing of the leeward. The soil’s moisture content distribution with different vegetation restoration measures in alpine semi-arid sandy land was affected by precipitation, soil distribution, species type, plant root distribution, and dunes’ micro-topography. Figures and Tables | References | Related Articles | Metrics

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Effects of grazing intensity on soil aggregates composition, stability, nutrients and C/N in desert shrubland QI Zhengchao,CHANG Peijing,LI Yongshan,TIAN Xuemei,LI Xudong,GUO Ding,NIU Decao 2021, 38 (1):  87-94.  doi: 10.13866/j.azr.2021.01.10 Abstract ( 370 )   HTML ( 11 )   PDF (2505KB) ( 196 )   We studied the effects of different grazing intensities upon soil physical-chemical properties, aggregates composition and stability, nutrients, and the C/N ratio in the Alxa desert steppe. We observed that heavy grazing decreased soil’s organic carbon and total nitrogen contents in the 0-5 cm, 5-10 cm, and 10-20 cm layers while increased soil’s bulk density compared to light grazing. In all layers, 0.053-0.250 mm aggregates were dominant. Both mean weight diameter and geometric mean diameter of soil aggregates decreased, whereas soil fractal dimension increased, indicating damages to the soil aggregates’ structure and stability decrease. Heavy grazing decreased larger soil aggregates (0.25-2.00 mm) to smaller ones (0.053-0.250 mm and <0.053 mm) and increased the C/N ratio of soil aggregates, limiting the release of available nutrients and causing nutrients deficiency. We conclude that heavy grazing is a vital degradation factor for the Alxa desert steppe’s soils. Figures and Tables | References | Related Articles | Metrics

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Effects of short-term nitrogen and phosphorus addition on unprotected soil organic carbon in desert grassland ZHANG Yarou,AN Hui,WANG Bo,WEN Zhilin,DU Zhongyu,WU Xiuzhi,LI Qiaoling 2021, 38 (1):  95-103.  doi: 10.13866/j.azr.2021.01.11 Abstract ( 387 )   HTML ( 4 )   PDF (4294KB) ( 344 )   To explore the response of the proportion of unprotected organic carbon and the transformation rate of unprotected soil organic carbon into protected soil organic carbon into nutrient addition, the content, proportion, and sensitivity index of particulate organic carbon (POC) and light fraction organic carbon (LFOC) were investigated under nitrogen (N) and phosphorus (P) addition in a desert grassland in arid and semiarid regions. The results showed that soil POC in topsoil (0-10 cm layer) significantly increased by 50%-70% under nutrient addition (N addition, P addition, and combined N and P addition), and the soil LFOC in topsoil significantly increased by 15%-31%. The proportion of unprotected organic carbon significantly increased under nutrient addition (25%-52%), but the conversion rate of unprotected soil organic carbon to protected soil organic carbon decreased (24%-42%). Soil organic carbon is mainly stored as unprotected organic carbon in desert grassland. The labile components of soil organic carbon increased as the proportion of unprotected organic carbon increased under short-term nitrogen and phosphorus addition. Therefore, nutrient addition was detrimental to the stability of soil organic carbon in desert grassland. Figures and Tables | References | Related Articles | Metrics

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The influence of alpine meadow degradation on soil conductivity change WANG Yingcheng,LU Guangxin,ZHAO Lirong,DENG Ye,WANG Junbang 2021, 38 (1):  104-113.  doi: 10.13866/j.azr.2021.01.12 Abstract ( 657 )   HTML ( 10 )   PDF (3711KB) ( 382 )   Grassland degradation is a complex and long-term process, and the most apparent sign of its occurrence is vegetation degradation (e.g., vegetation community composition, productivity, and spatial structure). During this process, soil physical-chemical properties change, impoverishing the soil and making it arider. Soil electric conductivity is an index for measuring the water-soluble salinity, reflecting soil salinization. To explore how the soil conductivity changes during the degradation of alpine meadow, whether the soil conductivity presents a regular change with the degradation of alpine meadow, just like the physical-chemical characteristics of vegetation and soil. Therefore, to analyze the influence of alpine meadow degradation on soil conductivity, we studied the undergraded and degraded alpine meadows in the Three River Source Region. We adopted a statistical test method to systematically analyze the relationship between vegetation and soil characteristics and the degraded alpine meadow’s soil conductivity. The degradation of alpine meadow significantly affected the vegetation coverage and biomass, causing the reduction of total soil nitrogen, organic matter, and moisture, turning it more infertile. We found that alpine meadow’s degradation negatively impacted soil conductivity. The soil conductivity showed a consistent trend with alpine meadow’s degradation indexes, including vegetation coverage, aboveground biomass, soil organic matter, and total nitrogen content. Therefore, we believe that alpine meadow’s degradation will change soil conductivity, and that these parameters can be used as an index of the degree of soil salinization and meadow degradation. Our study aims to reveal the characteristics of vegetation-soil conductivity during the alpine meadow’s degradation process, enrich the evaluation indexes of degraded alpine meadow, and provide a scientific basis for the early warning and restoration management of degraded alpine meadow. Figures and Tables | References | Related Articles | Metrics

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Characteristics of salinization and fertility of saline-alkali soil adjacent to drainage ditch in Hetao irrigation area of Inner Mongolia ZHOU Liying,LI Ruiping,MIAO Qingfeng,DOU Xu,TIAN Feng,YU Dandan,SUN Chenyun 2021, 38 (1):  114-122.  doi: 10.13866/j.azr.2021.01.13 Abstract ( 649 )   HTML ( 8 )   PDF (2343KB) ( 454 )   Reasonable improvement of saline-alkali soil in Hetao irrigation area adjacent to drainage ditch irrigation area can effectively promote ecological restoration and sustainable agricultural development. We analyzed saline-alkali soil’s salinization and fertility characteristics adjacent to drainage ditch irrigation area in Urad Front Banner with descriptive statistical analysis and principal component analysis. The soil in the study area has heavy chloride saline, with Mg2+ being the key cation of soil salinization. The excessive content slows down the absorption rate and increase soil’s alkalization rate. Soil’s alkalinity in 0-40 cm depth ranged from 13.0%-28.6%. The alkalinity degree we observed was caused because calcium carbonate could not prevent the soil from absorbing sodium ions. On the other hand, Mg2+ in soil could not promote Na+ adsorption, and there was a function correlation between soil’s pH, alkalinity, and total alkalinity. The principal component analysis results showed that the soil salinity, Cl-, Ca2+, Mg2+, pH, total alkalinity, and alkalinity were the main factors of soil salinization. The soil in the study area was potassium-rich, whereas other fertility levels were low. The soil adjacent to the drainage ditch belongs to compound saline-alkali chloride soil and alkaline soil. Such soils are hard to cultivate because of particle dispersion, muddy, impermeable characteristics, and low fertility, requiring soil enrichment with fertility elements other than potassium. Our study contributes significantly for analyzing the saline-alkali soil in the Hetao irrigation area, allowing rational land use policy and ecological improvement measures to be taken and incentivizing regional sustainable development. Figures and Tables | References | Related Articles | Metrics

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Application of stable carbon isotope technique in soil organic carbon research: A literature review LIU Lizhen,PANG Danbo,WANG Xinyun,CHEN Lin,LI Xuebin,WU Mengyao,LIU Bo,ZHU Zhongyou,LI Jingyao,WANG Jifei 2021, 38 (1):  123-132.  doi: 10.13866/j.azr.2021.01.14 Abstract ( 966 )   HTML ( 21 )   PDF (641KB) ( 604 )   Soil carbon turnover is an important part of carbon transfer between the atmosphere, biosphere, and lithosphere. Even small changes in the soil carbon pool could affect the atmospheric CO2 concentration and dynamic carbon above and underground. Stable carbon isotope technology is currently used widely in carbon biogeochemical cycle research at different time and space scales. However, there is a lack of integration of this technology with soil carbon turnover research. This literature review examined numerous studies on the application of stable carbon isotope technology to soil carbon origin, turnover, and dynamic changes. It also analyzed stable carbon isotope (δ13C) variations in the leaf-litter-soil leaf-soil continuums, and terrestrial ecosystems; focusing on (1) the characteristics of stable carbon isotope technology in the soil carbon cycle, (2) the main factors influencing the cycle, (3) the adaptive rules of soil carbon cycle turnover, (4) the similarities and differences between natural and artificial13C labeling methods, and (5) the aspects of future research integration that should be emphasized. This review could elucidate the role of soil carbon sources and sinks in terrestrial ecosystems and soil organic carbon turnover mechanisms and processes. Figures and Tables | References | Related Articles | Metrics

Weather and Climate

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Analysis of the upper-air temperature change in Xinjiang region ZHANG Liancheng,ZHANG Taixi,MAO Weiyi,SI Jiayi,ZHANG Tongwen,WANG Shengli 2021, 38 (1):  133-143.  doi: 10.13866/j.azr.2021.01.15 Abstract ( 600 )   HTML ( 14 )   PDF (5651KB) ( 321 )   Here, we analyzed the mean annual variations in upper-air temperature features in the Xinjiang region with the NCEP/NCAR reanalysis dataset. We used stepwise regression to interpolate the missing values in the measured data and verified them using a cross-validation method. We analyzed the change in upper-air temperature both in the coldest (January) and the warmest (July) months. Additionally, we verified the NCEP/NCAR data’s accuracy in both January and July with the upper-air measured data. The results indicated that the measured data can describe the upper-air temperature in Xinjiang more accurately after interpolation. We examined the average temperature trends in the troposphere (at the bottom, middle, and upper layers) and the lower stratosphere on both the coldest and warmest months and throughout the year. As the height rises, the temperature trend changes from warming to cooling temperatures. The critical height at which the temperature trend reverses is higher during the warmer months. In most years after 2000, the air temperature exhibited a warm anomaly in the troposphere a cold anomaly in the lower stratosphere. The turning point in the annual mean temperature anomaly, which turned from cold to warm, occurred in 1996 at both 850 hPa and 700 hPa levels. However, between 1995 and 1997, it happened at the 100 hPa level, showing a warm to cold trend. The temperature anomaly did not change abruptly between 500 hPa and 300 hPa. The NCEP/NCAR data and measured data in January and July had a correlation coefficient mostly above 0.9, indicating a relatively small error. Figures and Tables | References | Related Articles | Metrics

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Precipitation characteristics in alluvial fan in the north and south of Kumtag Desert based on measured data PANG Yingjun,WU Bo,KONG Deyong,GAO Junliang 2021, 38 (1):  144-153.  doi: 10.13866/j.azr.2021.01.16 Abstract ( 464 )   HTML ( 5 )   PDF (4129KB) ( 365 )   This study analyzed the precipitation characteristics in detail using the field precipitation data from June 2017 to May 2018 in alluvial fan in the north and south of Kumtag Desert. The results are as follows: (1) Due to the effect of geographical location, topography, etc. , the spatial distributions of precipitation in Kumtag Desert vary greatly. The minimum annual precipitation in Sanlongsha, Beishan alluvial fan in the north of Kumtag Desert, is 21. 6 mm. The precipitation in Altun alluvial fan in the south of Kumtag Desert gradually increases from west to east, and the annual precipitation in upper reach of Huyang, Wushikate, Saimagou, and Duobagou ditches is 73.0、75.2、176.0 mm, and 137.4 mm, respectively. The precipitation in Altun alluvial fan in the south of Kumtag Desert gradually increases from the north to south and the annual precipitation in lower and middle reaches of Huyang ditch is 58.0 and 56.4 mm, respectively, which is lower than that in upper reach of Huyang ditch. (2) The precipitation in alluvial fan in the north and south of Kumtag Desert mainly occurs from May to August and the cumulative precipitation can account for more than 90% of full year. (3) The number of precipitation events in alluvial fan in the north and south of Kumtag Desert lies between 11 and 26, and a small number of large precipitation events contributes immensely to the total annual precipitation. Figures and Tables | References | Related Articles | Metrics

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Simulation characteristics of planetary boundary layer parameterizations: A case study in Xinjiang during summer ZHANG Hailiang,LI Huoqing,Ali Mamtimin 2021, 38 (1):  154-162.  doi: 10.13866/j.azr.2021.01.17 Abstract ( 542 )   HTML ( 10 )   PDF (3783KB) ( 169 )   Planetary boundary layer (PBL) parameterization has significant impacts on the simulation and prediction of climate, weather, and environmental air quality. Here, ideal experiments were conducted using the single-column model to study the response characteristics of specific humidity and potential temperatures on soil moisture under different PBL parameterizations. A heavy precipitation synoptic process in Xinjiang from 15th-18th August 2019 was simulated and verified with six PBL parameterizations, including YSU, ACM2, BOULAC, GBM, MYJ, and QNSE. As the soil moisture increases, the simulated atmospheric boundary layer presents significant characteristics, namely, increasing specific humidity, decreasing potential temperatures, and decreasing boundary layer height. In GBM and ACM2 cases, the vertical water vapor transport efficiency was low, atmospheric specific humidity was also low, the potential temperature was high, eddy action scope was large, and precipitation was underestimated. In QNSE and MYJ cases, the vertical water vapor transport efficiency was high, atmospheric specific humidity was high, the potential temperature was low, eddy action scope was small, and precipitation was overestimated. The maximum 2 m specific humidity was achieved using QNSE and MYJ, while the minimum 2 m specific humidity was by ACM2. The lowest 2 m temperature was achieved at nighttime using QNSE, while the highest 2 m temperature was at daytime using MYJ. The highest 10 m wind speed was achieved using QNSE and MYJ. These simulating characters are closely related to the differences in the vertical water vapor transport efficiency of the different PBL parameterizations. Figures and Tables | References | Related Articles | Metrics

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Impact of boundary layer parameterization schemes on the simulation of a dust event over Northwest China WEI Qian,LONG Xiao,ZHAO Jianhua,HAN Zifei,WANG Siyi 2021, 38 (1):  163-177.  doi: 10.13866/j.azr.2021.01.18 Abstract ( 535 )   HTML ( 11 )   PDF (9745KB) ( 279 )   In this study, WRF-Chem(version 3.4) model was used to compare the performance of different Planetary Boundary Layer (PBL) parameterization namely, the YSU(Yonsei University), MYJ(Mellor-Yamada-Janjic), QNSE(Quasi-Normal Scale Elimination), MYNN2.5(Mellor-Yamada-Nakanisfii and Niino 2.5) and BouLac PBL schemes, over the dust event in northwest china on 27 March 2007. Surface observations were used for comparisons and evaluating model performance for meteorological variables. It is shown that simulations with the five PBL schemes can successfully reproduce the evolution of the dust event. The YSU and BouLac schemes produced higher surface friction velocity, 10 m wind speed, 2 m air temperature and surface PM10 concentration and lower 2-mrelative humidity, thus simulating stronger weather processes than those of the MYJ, QNSE and MYNN2.5 schemes. These results indicate that different boundary layer schemes affect the dust emission flux and PM10 concentration through different simulation effects of friction velocity. The dust emission flux and PM10 concentration tend to increase with higher friction velocity. Therefore, the dust event was enhanced due to the high friction velocity and the characteristics of high temperature as well as lower humidity in near-surface layer in the afternoon. As a result, the simulated dust event with the BouLac scheme was the strongest while the weakest by the QNSE scheme. Observations from Minqin meteorological station are used to validate the simulated results over Minqin region. Statistical analysis of the five simulations shows that the QNSE scheme simulated better PM10 concentration, the BouLac scheme performs well for 10 m wind speed and the YSU scheme resulted in the best model performance for simulating air temperature and relative humidity at 2 m. Overall, the YSU scheme was concluded as the best PBL scheme for the dust storm and the QNSE scheme was the worst one. Figures and Tables | References | Related Articles | Metrics

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Spatial-temporal variation characteristics of land surface temperature in Qinghai Province from 1980 to 2017 ZHAO Meiliang,CAO Guangchao,CAO Shengkui,LIU Fugang,YUAN Jie,ZHANG Zhuo,DIAO Erlong,FU Jianxin 2021, 38 (1):  178-187.  doi: 10.13866/j.azr.2021.01.19 Abstract ( 714 )   HTML ( 24 )   PDF (4232KB) ( 337 )   Land surface temperature is an important factor affecting the regional climate, agricultural production, and soil nutrients. It is of great significance to analyze the variation law of ground temperature to understand the causes of climate change and the layout of agricultural production. The characteristics of land surface temperature change and its relationship with the meteorological factor in the Qinghai Province were studied by using linear trend analysis, the Mann-Kendall mutation test, and wavelet analysis based on the data of daily land surface temperature, air temperature, and wind speed data from 35 meteorological stations in the study area from 1980 to 2017. The results showed that: (1) The annual average land surface temperature in Qinghai Province showed a fluctuating and rising trend at a rate of 0.68 °C·(10a)-1（P<0.01）, and the mutation point was in 2001. There was a significant seasonal difference in the change of surface temperature, and the rate of change was most obvious in winter, which was 0.77 °C· (10a)-1 (P<0.01). There was little difference in the other seasons. The average annual land surface temperature of Qinghai Province was based on two periodic changes of 4-7 a and 11-16 a. (2) The average annual land surface temperature of two low-temperature centers in the Qingnan plateau and Qilian mountain area was compared with two high-temperature centers of the Qaidam Basin and Eastern agricultural area, and the rate of temperature increase of the low-temperature center was faster. (3) The annual and quarterly average land surface temperatures had a significant positive correlation with the average temperature but were negatively correlated with wind speed and altitude. (4) The average surface temperature showed an obvious vertical decreasing pattern, and the warming trend was more obvious in areas with high altitude. Figures and Tables | References | Related Articles | Metrics

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Spatio-temporal evolution of the extreme dry and wet events in Tianshan Mountains, Xinjiang, China CAO Lijun,SUN Huilan,LAN Xiaoli,ZHANG Lele,LU Baobao,LIU Tianyi 2021, 38 (1):  188-197.  doi: 10.13866/j.azr.2021.01.20 Abstract ( 563 )   HTML ( 5 )   PDF (9795KB) ( 120 )   The FAO Penman-Monteith model was used to calculate the monthly surface humid index at 26 meteorological stations in the Tianshan Mountains, Xinjiang, China, based on their meteorological data from 1960 to 2017. The extreme dry and wet event frequencies were calculated after standardizing the data. Subsequently, the Mann-Kendall trend analysis and inverse distance weighting methods were used to explore their spatio-temporal evolutionary characteristics. Pearson and partial correlation analyses and cross wavelet transform were used to investigate the influence of meteorological factors and atmospheric circulation on the extreme dry and wet events. The results showed that (1) the interannual decrease and increase in extreme dry and wet events were -0.40 and 0.37 times per decade, respectively. The highest occurrence of extreme dry and wet events and the largest decrease in extreme dry events occurred in summer, while the largest increase in extreme wet events was in autumn; (2) the northern slope exhibited the highest incidence of extreme dry and wet events, with a frequency of 4.36 and 2.76 times a year, respectively. It also exhibited the fastest rate of decline in extreme dry and increase in extreme wet events, with an average annual incidence of -0.75 and 0.58 times per decade, respectively; and (3) the average relative humidity was the primary meteorological factor influencing the changes in extreme dry and wet events in the region, and the El Ni?o-Southern Oscillation was the main atmospheric circulation factor. Figures and Tables | References | Related Articles | Metrics

Plant and Plant Physiology

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Physiological and biochemical characteristics and adaptability of Tamarix taklamakanensis in different ecological habitats in the Tarim Basin SU Zhihao,ZHOU Xiaobing,JIANG Xiaolong,WANG Liuqiang,GONG Yanming,KANG Xiaoshan 2021, 38 (1):  198-206.  doi: 10.13866/j.azr.2021.01.21 Abstract ( 430 )   HTML ( 11 )   PDF (2689KB) ( 212 )   Tamarix taklamakanensis is a tree endemic to China and it is the most drought-resistant species in drifting sand dunes within the Tarim Basin. It plays an important role in sand fixation and desert prevention. We selected populations in three different habitats (green belt near the desert road, gravelly desert in riverbed, and drift sand dunes) to quantify the water status, chlorophyll contents, antioxidant enzyme activities, and osmotic adjustment substances contents. We evaluated the species’ physiological and biochemical characteristics in different habitats and its adaptive mechanisms to deal with extreme drought conditions. In soils with low moisture content, superoxide dismutase (SOD) activities, peroxidase (POD) activities, total antioxidant capacity, and soluble protein contents increased, whereas catalase (CAT) and nitrate reductase (NR) activities decreased. In the driest drift sand dune habitat, the population had highest chlorophyll a and soluble sugar contents. Under drought stress, T. taklamakanensis increased SOD and POD activities and total antioxidant capacity, while it decreased CAT and NR activities to maintain the metabolic balance of reactive oxygen. It increased soluble protein, soluble sugar, and malondialdehyde to maintain high osmotic adjustment ability for resisting drought environments. Figures and Tables | References | Related Articles | Metrics

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Study on the relationship between vegetation community characteristics and soil moisture in Badain Jaran Desert QIN Jie,SI Jianhua,JIA Bing,ZHAO Chunyan,LI Duan,LUO Huan,REN Lixin 2021, 38 (1):  207-222.  doi: 10.13866/j.azr.2021.01.22 Abstract ( 548 )   HTML ( 11 )   PDF (3523KB) ( 339 )   Following investigation and sampling of Badain Jaran Desert periphery and hinterland, this study has summarized the life forms and community types of vegetation in the area, analyzed the diversity, dominance, and evenness index of vegetation, and then investigated the response of vegetation community to soil water. The results obtained are as follows. First, a total of 52 genera and 56 species of plants belonging to 20 families were recorded in this survey, which belonged to 8 types of life forms, including arbors, small arbors, shrubs, small shrubs, semi-shrubs, grassy vines, perennial herbs, and annual herbs. The vegetation communities were mostly shrubs and perennial herbs, and most of them were desert xerophytes or super xerophytic perennials. Second, the overall biodiversity index of the Badain Jaran Desert community is low, whereas the species richness and diversity indices around the lakes in the desert hinterland are relatively high, and those in the marginal area are low. The shrub layer is dominant and uniformly distributed in the plant community, and the herb layer consists of various forms of vegetation. Third, the Badain Jaran Desert has low soil water content, and more than 61% of the region has less than 5% soil moisture. The soil moisture content is negatively correlated with the Simpson dominance index (C), and positively correlated with the Shannon-Winner diversity index (H′), Simpson Diversity Index (D), and Alatato uniformity index (Ea). Additionally, Simpson Dominance Index (C), Shannon-Winner Diversity Index (H′), and Simpson Diversity Index (D) have good cubic function fitting effect on response relations of soil moisture. Figures and Tables | References | Related Articles | Metrics

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Study on vegetation community characteristics and soil physical and chemical properties of abandoned land in Qingtu Lake HE Hongsheng,TIAN Qing,WANG Lide,MENG Cunhong,HE Fanglan,GUO Chunxiu,WU Hao 2021, 38 (1):  223-232.  doi: 10.13866/j.azr.2021.01.23 Abstract ( 389 )   HTML ( 8 )   PDF (643KB) ( 281 )   We selected arable areas with different years of abandonment (1 a, 2 a, 4 a, 8 a, 13 a, 20 a, 30 a, 40 a, and CK) as research objects and used the space-time substitution method to analyze the vegetation community and soil physical-chemical characteristics during the restoration period at the Qingtu Lake. Our results showed that 15 plant families, with 29 genera and 43 species appeared in our plots during the 40-year restoration process, with most species belonging to a few plant families and few species belonging to one dominant plant family. We divided the vegetation restoration process into four stages. The first rapid-recovery stage (grain for 1a to 2 a) is composed of annual and perennial root herbs; the second stage (grain for 2 a to 8 a) is composed of annual herbaceous and perennial herbaceous plants; in the third stage (grain for 8 a to 20 a), perennial herbaceous and perennial shrub are the most common species; and perennial shrubs dominate the fourth final succession stage (grain for 20 a to 40 a). In areas where farming activities were more intensive, the soil-water content was more volatile, with increasing and decreasing periods. In the final succession stage, the topsoil layer had more moisture in compasrison to the lower-soil layer. Independent of the restoration stage, the proportion of fine sand grains was the largest, followed by the proportion of powder grains, whereas the proportion of coarse sand grains and clay grains were the smallest, and these particle proportions did not change depending on time and intensity of farming activities. We observed that according to the intensity of the farming activities, both total nitrogen and organic matter showed a downward trend. Still, the soil’s available potassium first increased and then decreased, whereas the available phosphorus showed the opposite trend. The surface aggregation phenomenon was evident. Finally, the succession of the vegetation community was closely related to soil physical-chemical properties. The Margalef richness index positively correlated with total soil nitrogen and organic matter, whereas the Shannon diversity index positively correlated with soil bulk density and fine sand particles and negatively correlated with soil clay and silt particles. The 4th year of the return of farming activity was crucial in the recovery process at Qingtu Lake. Figures and Tables | References | Related Articles | Metrics

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Comparative study on the reed rhizospheric microenvironment and reed rhizome growth and development in different habitats WANG Ting,LI Chaozhou,JIAO Jian,ZHI Xianghong 2021, 38 (1):  233-240.  doi: 10.13866/j.azr.2021.01.24 Abstract ( 523 )   HTML ( 3 )   PDF (7144KB) ( 302 )   Comparative study on the reed rhizospheric microenvironment and reed rhizome growth and development in four different habitats were reported in this paper. The rhizome and reed rhizospheric soil in four habitats (sand dune habitat, transitional habitat from saline to sand dune, saline habitat, marsh habitat) were studied in Linze County. Relevant indicators, such as the growth and development indexes of the reed rhizome, quantity of microorganisms, soil water, and soil salt content, were determined in the rhizospheric soil of different habitats. Based on the analysis, the relationship between the growth and development of the rhizome and the quantity of microorganisms, water content, and salt content in rhizospheric soil in different habitats was elucidated. The results showed that: (1) There were significant differences in the biomass of the reed rhizome among the four habitats, among which the internodal length was largest in the four habitats. The pitch diameter, biomass, water content, and length of the rhizome as well as the number of adventitious buds were smallest under the salt habitat, which showed that the growth of the reed rhizome was inhibited by saline soil. Compared with the development of the rhizome in four habitats, from salt habitat to salt-dune transition habitat to sand dune habitat, and then to marsh habitat, which were manifested as a shortening trend of internodal length, thickening trend of pitch diameter, and increasing trend of rhizome length, adventitious bud number, rhizome water content, and rhizome biomass. (2) There were significant differences in the number of rhizospheric soil microorganisms among the four habitats; the highest salt content of reed rhizospheric soil, largest number of soil fungi, and smallest number of bacteria and actinomycetes were found in the salt habitat. The smallest number of fungi and the largest number of bacteria and actinomycetes existed in the marsh habitat. (3) A correlation analysis showed that the number of soil microorganisms in the reed rhizosphere had different driving effects on the number characteristics of reed rhizomes. The number of soil bacteria, actinomycetes, and B/F value are the main influencing factors of the reed rhizome length, rhizome node diameter, rhizome biomass, rhizome water content, plant height, and base diameter. Soil fungi are the main influencing factors of reed rhizome node spacing. Soil bacteria, fungi, actinomycetes, and B/F were the main factors affecting the number of adventitious buds. Soil bacteria, actinomycetes, and B/F value were positive driving factors, whereas fungi were negative driving factors. The oil water content has the greatest direct effect on the number of soil bacteria in the rhizosphere, and the soil salt content has a negative direct effect on the number of soil bacteria. Soil salinity has an indirect effect on soil bacteria through the soil water content. Soil salinity has the greatest direct effect on soil fungi, and soil water content has a greater indirect effect on soil fungi through soil salinity. It has a negative direct effect on soil actinomycetes, and the soil salt content has a greater indirect effect on soil actinomycetes through the soil water content. Figures and Tables | References | Related Articles | Metrics

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Floristic analysis of woody plants in the northern foot of Yinshan Mountain FENG Shuang,LAN Dengming,ZHAO Hongsheng,ZHAO Xinghua,GUO Lu 2021, 38 (1):  241-246.  doi: 10.13866/j.azr.2021.01.25 Abstract ( 466 )   HTML ( 9 )   PDF (716KB) ( 418 )   The northern foot of Yinshan Mountain is a typical transition area from grassland to the desert, which has a particularly rich and complex species composition, plant community structure, and ecological function. Using the theory and methods of floristic geography and field investigation, we assessed the floristic and geographic compositions of woody plants in the northern foot of Yinshan Mountain. Our results show that the woody flora consists of 68 species, 38 genera, and 16 families. Three dominant families with more than ten woody plant species were observed, including two genera and one species. Thirty-one genera accounted for 81.58% of the genera richness. Five distribution types and one distribution form in the flora family distribution was seen, and the world distribution type was dominant. Eleven distribution types and four distribution forms of floristic geographical elements were seen, and the temperate distribution type was dominant. Figures and Tables | References | Related Articles | Metrics

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Effects of drought stress and arbuscular-mycorrhizal fungi on root growth, nitrogen absorption, and distribution of two desert riparian plant seedlings SANG Yu,GAO Wenli,Zainur Tursu,FAN Xue,MA Xiaodong 2021, 38 (1):  247-256.  doi: 10.13866/j.azr.2021.01.26 Abstract ( 527 )   HTML ( 9 )   PDF (2005KB) ( 396 )   Arbuscular mycorrhizal fungi (AMF) play an essential role in plants’ drought resistance and nutrient absorption. We studied the dominant shrub, T. ramosissima, and the common subshrub, Alhagi sparsifolia, in the desert riparian forest in the lower reaches of the Tarim River. The inoculation of AMF under drought stress management (CK and S, soil relative water contents of 70% ± 5% and 20% ± 5%) and the single (TR, AS) and mixed planting (TR + AS) modes was analyzed. Also, the effects of inoculation and non-inoculation of AMF on the growth and root characteristics of T. ramosissima and A. sparsifolia were compared. The results showed that (1) under drought stress, the mycorrhizal infection rate of T. ramosissima and A. sparsifolia decreased, and the mycorrhizal infection rate of T. ramosissima seedlings increased significantly under mixed planting. (2) Under drought stress, the under-and aboveground biomass of T. ramosissima seedlings increased significantly under mixed planting. (3) Under drought stress, AM significantly increased the roots’ length and surface area of their fine roots under different planting modes and significantly reduced the specific root length of the A. sparsifolia. Also, the ratio of fine roots to root length of T. ramosissima seedlings under M+ treatment was significantly reduced. (4) Compared with single planting, AMF significantly increased the nitrogen intake and distribution ratio in the aboveground part of T. ramosissima seedlings under drought stress. Therefore, AMF has a compensatory effect on the growth and nitrogen absorption of T. ramosissima seedlings mixed with A. sparsifolia under drought stress, which is beneficial for T. ramosissima seedlings in the lower reaches of the Tarim River to survive the fragile growth period. Figures and Tables | References | Related Articles | Metrics

Ecology and Environment

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Magnetic properties of Lop Nur saline sediments and the environmental implications LI Wen,MU Guijin,LIN Yongchong,ZHANG Huijuan,WU Wangyang 2021, 38 (1):  257-266.  doi: 10.13866/j.azr.2021.01.27 Abstract ( 478 )   HTML ( 10 )   PDF (3791KB) ( 289 )   This article presents the particle size, total organic matter, rock magnetic, and x-ray diffraction analyses of saline lake sediments, aeolian sands, Tramarix cone, and yardangs sediments distributed along the west bank of Lop Nur. The aim was to investigate the vertical variations and influencing factors of magnetic characteristics, as well as the paleoenvironmental implications. Based on the magnetic properties, Lop Nur sediments can be divided into two types. In oxidizing environments, sediment magnetic properties are dominated by magnetite, which is consistent with the source materials (Tarim Basin) and are unaffected by early diagenesis. In reducing environments, sediment magnetic properties are dominated by authigenic iron sulfide (greigite and pyrite), which formed in the early diagenesis process. Layers that are dominated by greigite or pyrite have markedly higher or lower χ, SIRM, χARM, and χARM/χ and S-300 mT, respectively, reflect the significant impact of early diagenesis on magnetic properties in the Lop Nur. Combined with the results of chronology from a previous study, we determined that the iron sulfide-bearing sediments were deposited during cold and wet periods, which were probably caused by the North Atlantic cold events that occurred throughout the past 3400 yr. During these periods, iron sulfide formation was likely driven by an enhanced organic matter supply. The magnetic parameters of Lop Nur sediments can be regarded as an indicator of the hydrological and climatic evolution of the Tarim Basin. Figures and Tables | References | Related Articles | Metrics

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Study on change in carbon storage and its spatial pattern in Mata Watershed from 1999 to 2016 based on InVEST model LIU Guan,LI Guoqing,LI Jie,ZHANG Yanru,LU Qi,DU Sheng 2021, 38 (1):  267-274.  doi: 10.13866/j.azr.2021.01.28 Abstract ( 640 )   HTML ( 29 )   PDF (2848KB) ( 393 )   The soil and water conservation forests in the areas surrounding Yan’an city are being replaced by economic forests such as orchard, which will definitely have an impact on the regional carbon storage. Therefore, it is necessary to determine a method to quantify the impact of orchard construction on the regional carbon storage capacity. Based on the InVEST model and ArcGIS platform, this study evaluated the change in carbon storage in the Mata Watershed in southern Yan’an from 1999 to 2016, and explored the influence of slope, slope aspect, and slope position on the spatial distribution of change in carbon storage. The results showed that the carbon storage of forest, grassland, and orchard has increased, whereas that of shrub, cropland, and other lands has declined during the 18 years of vegetation and reconstruction in the Mata Watershed (mainly orchard construction). The regional total carbon storage has increased by 7.63%, of which 39.71% has been contributed by orchard. The increase in spatial position of carbon storage was mainly located in half-shaded-slopes, middle, and top of slopes; as well as slopes with range of 10°-30°. This study provides a methodological case study for quantifying the impact of economic forest construction on regional carbon storage function in the loess hilly region. Figures and Tables | References | Related Articles | Metrics

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Analysis of canopy light interception and dry matter distribution characteristics of different winter wheat yield groups in Xinjiang WANG Lihong,ZHANG Hongzhi,LI Jianfeng,WANG Zhong,GAO Xin,SHI Jia,ZHANG Yueqiang,FAN Zheru,ZHAO Qi 2021, 38 (1):  275-282.  doi: 10.13866/j.azr.2021.01.29 Abstract ( 375 )   HTML ( 4 )   PDF (1272KB) ( 234 )   The effects of photosynthetically active radiation (PAR) interception, dry matter distribution, and the yield of winter wheat at different yield levels were studied to provide a theoretical basis for narrowing the yield gap, improving the utilization of light energy resources, and high-yield cultivation of winter wheat in the Xinjiang province. This experiment was conducted in Junhu and Qitai regions from 2018 to 2019. The main varieties planted in the region were used as experimental materials, and the integrated management model was adopted to simulate the four yield levels, namely, super high (SH: ≥9000 kg·hm-2), high (HH: 7500-9000 kg·hm-2), peasant household (FP: 6000-7500 kg·hm-2), and basic yields (CK: ≤4500 kg·hm-2). The characteristics of light interception, dry matter accumulation, and distribution in the upper, middle, and lower canopies of winter wheat at the four yield levels were studied, and the correlation between them and yield composition was analyzed to explore ways of increasing yield. The results showed that the population with a high-yield level could still maintain a high leaf-area index (LAI) during its grouting stage. With production level increased, PAR interception rate and volume in the upper, middle, and lower layers of the canopy all increased, and the overall performance was greater in the upper than in the middle layer, presenting a vertical distribution characteristic of “strong at the top and weak at the bottom.” The variation trend of PAR transmittance was opposite. Dry matter accumulation in the middle layer was lower than in the upper and lower layers, and dry matter increase in the upper layer was greater than in the middle and lower layers, with an increase in yield level. The dry matter accumulation in the upper, middle, and lower layers was significantly correlated with the PAR interception rate, and the correlation coefficient with grain yield was 0.97, 0.90, and 0.78, respectively. Therefore, maintaining high LAI, increasing PAR interception, and increasing dry matter accumulation after flowering are approaches to achieving increased wheat yield and reduced yield difference. Figures and Tables | References | Related Articles | Metrics

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Tensile resistance of mechanical sand barriers: A case study of high vertical and flat sand barrier along Lince Railway JIA Guangpu,ZUO Hejun,YAN Min,HAN Xueying,Yao Yunfeng 2021, 38 (1):  283-292.  doi: 10.13866/j.azr.2021.01.30 Abstract ( 342 )   HTML ( 3 )   PDF (3670KB) ( 234 )   Suitable sand-resisting and sand-fixing materials were selected in order to reveal the tensile properties of mechanical sand barriers. We used the TY8000 series servo controller to conduct longitudinal tensile evaluation on the test objects. Our results indicated that when the porosity is uniform (full-sparse or full-dense), the width of sand barriers made up of different materials is positively correlated with the power function, whereas the tensile strength is negatively correlated with the power function. When the material is the same, the tensile strength and elongation change form unimodal curves. The width of sand barriers with different porosity and its tensile strength are positively correlated with the power function and negatively correlated with the tensile strength. The tensile forces of uniform sand barriers are unimodal, while that of mixed type (sparse upper and lower dense) sand barriers are bimodal. When the width of the sample is greater than 4 cm, the upper sparse and lower dense elongation is greater than the elongation of full dense type, followed by that of the full sparse type, with sizes of 141.23±2.56 mm (mean±standard deviation), 103.46±3.20 mm, and 63.50±1.20 mm, respectively. The values recorded for large sample width are smaller than those recorded for small sample width. The “necking” phenomenon occurs due to the local wire mesh’s uneven force during the process. We recommend using the upper sparse and lower dense sand barriers when laying in the field. Depending on the existing local wind conditions, the tensile properties of sand barrier materials should be pre-tested indoors to avoid problems due to insufficient wind protection and maximize the benefits of sand fixation. Figures and Tables | References | Related Articles | Metrics