Table of Content

15 July 2021, Volume 38 Issue 4 Previous Issue    Next Issue

Water Resources and Utilization

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Effect of ecological water conveyance on groundwater depth and vegetation in the Kongque River LIU Lu,CHEN Yapeng,LI Xiaoyang 2021, 38 (4):  901-909.  doi: 10.13866/j.azr.2021.04.01 Abstract ( 474 )   HTML ( 37 )   PDF (6235KB) ( 306 )   To understand changes in groundwater depth and vegetation after ecological water conveyance, the spatial and temporal variation characteristics of groundwater depth, the relationship between groundwater depth and cumulative water volume, and changes in the normalized difference vegetation index (NDVI) and vegetation coverage after water conveyance were analyzed using statistical methods and remote sensing image data. In regards to temporal variation, the results showed a steady upward trend in the groundwater depth of the Kongque River after ecological water transfer, and that the yearly change in groundwater depth was mainly caused by human agricultural production. In regards to spatial change, the range of rising groundwater depth decreased with increasing distance in each perpendicular section to the river channel. The change of the buried depth of the middle reach along the river direction was the largest. There was a negative correlation between groundwater depth and cumulative ecological water delivery. The correlation of the middle reach section was the most significant. From 2016 to 2019, the NDVI of the upstream and midstream sections increased by 64.28% and 100%, respectively, whereas the NDVI value of the downstream reach was stable at 0.05. The vegetation coverage within 2 km from the three river reaches showed an increasing trend. Thus, ecological water conveyance had a positive effect on groundwater depth and vegetation in Kongque River Basin. These results suggest that a reasonable water conveyance amount should be maintained to strengthen groundwater supervision and control, and to protect ecological security. Figures and Tables | References | Related Articles | Metrics

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Evaluation of water resource exploration potential of the China-Mongolia-Russia Economic Corridor based on carrying capacity LI Li,LIU Shiqi,WANG Ping,QIAO Yuan,WANG Tao,WANG Tianye,LI Zehong,Tcogto Bazarzhapov 2021, 38 (4):  910-918.  doi: 10.13866/j.azr.2021.04.02 Abstract ( 562 )   HTML ( 21 )   PDF (7886KB) ( 240 )   In this study, the data of surface water resources, precipitation, population, and gross domestic product for 43 provincial administrative units in the China-Mongolia-Russia economic corridor in 2016 were used to systematically analyze the distribution characteristics and development potential of water resources in these regions by calculating the carrying capacity of water resources. We found that there were more surface water resources in the north and east of the China-Mongolia-Russia economic corridor and less in the west and south, with the middle of the area having the least water resources. Provincial administrative units in Russia were rich in surface water resources, accounting for about 95% of the total surface water resources of the economic corridor. These administrative units in Russia were characterized by having a low population, low demand for water resources, low exploitation and utilization, and high potential for water resources development. Regions in Mongolia were relatively rich in surface water resources in the north, with five administrative regions having a water resources carrying capacity of less than one, which indicates potential for development. However, there was a severe shortage of surface water resources found for the southern part of the Mongolia are in the economic corridor. For three northeastern provinces and the Inner Mongolia Autonomous Region of China, the development potential of water resources is low, as their water resources carrying capacities are more than two due to relatively high population densities and the high demand for water resources. The water resources carrying capacity in these regions was higher than two and had low development potential. From the perspective of optimal regional water allocation, the southern part of Mongolia and the four provinces (autonomous regions) of China are the key areas that require the optimal allocation of water resources. There are opportunities in Russia to solve water shortage problems in other regions of the China-Mongolia-Russia Economic Corridor. However, as the exploitation of water resources is closely linked to socio-economic development of each area, cooperation over water resources within the China-Mongolia-Russia economic corridor requires further study. Figures and Tables | References | Related Articles | Metrics

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Simulating surface energy and mass balance of the Puruogangri ice cap during 2012-2014 based on High Asia Refined analysis data LI Jianjiang,LI Jia,WU Lixin,WANG Yingzheng,GUO Lei 2021, 38 (4):  919-929.  doi: 10.13866/j.azr.2021.04.03 Abstract ( 421 )   HTML ( 18 )   PDF (4521KB) ( 560 )   Glacier mass balance is an important parameter for describing how glaciers respond to climate change. The Puruogangri ice cap is the largest ice cap on the Tibetan Plateau, and the retrieval of its mass balance is of great significance. In this study, the surface energy balance and mass balance of the Puruogangri ice cap between April 23, 2012 and May 11, 2014 were simulated from the High Asia Refined analysis data via the coupled snowpack and ice surface energy and mass balance model(COSIMA). Based on simulated surface energy balance and mass balance, we revealed the ablation mechanism of the Puruogangri ice cap and the reason why ablation accelerated between April 23, 2012 and May 11, 2014. From April 23, 2012 to May 23, 2013 and May 23, 2013 to May 11, 2014, the simulated mass balance values of the Puruogangri ice cap were -0.18 m w. e. and 0. 36 m w. e., respectively. These results were consistent with the previously reported result (-0.13 ± 0.03 m w. e. and -0. 34 ± 0.06 m w.e., respectively) that was derived by differencing the digital elevation models obtained at different times. The simulated mass balance indicated that the low areas, such as the western parts of the ice cap, experienced mass loss, while the high areas, such as the northern part of the ice cap, experienced mass gain. The maximum mass loss and gain during the observation period were 2.69 m w. e. and 0.85 m w. e., respectively. The energy used for ablation between May 23, 2013 and May 11, 2014 was less than that used between April 23, 2012 and May 23, 2013. Therefore, the surface ablation was weakened between May 23, 2013 and May 11, 2014. However, the solid precipitation between May 23, 2013 and May 11, 2014 was also less than that between April 23, 2012 and May 23, 2013; therefore, the net surface mass balance of the ice cap decreased between May 23, 2013 and May 11, 2014. Figures and Tables | References | Related Articles | Metrics

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Indication of hydrogen and oxygen stable isotopes in Dali Lake for evaporation and replenishment sources GUO Xin,LI Wenbao,SUN Biao 2021, 38 (4):  930-938.  doi: 10.13866/j.azr.2021.04.04 Abstract ( 431 )   HTML ( 5 )   PDF (3884KB) ( 389 )   The goal of this study was to study the applicability of the stable isotope mass balance method in the calculation of the water balance of Dali Lake in the Inner Mongolia Plateau. The water bodies of the Dali basin were collected three times in the summer of 2018, and surface water and ice samples were collected from the lakes during the winter. The stable hydrogen and oxygen isotopes (δD, δ18O) were tested in the different water samples. Then, the stable isotope mass balance method was used to calculate water evaporation and recharge from Dali Lake, and δD was used to analyze the source of water evaporation and recharge. The results showed that the stable isotopic spatial variability of hydrogen and oxygen in the Dali Lake water body was low, and the rate of enrichment of the water body continued to decrease in summer, which was mainly affected by the precipitation process. During winter, stable hydrogen and oxygen isotopes were enriched in the ice, which is mainly affected by the freezing process. The groundwater was hardly affected by the local atmospheric precipitation. The δ 18O-δD relation point of Dali Lake falls to the lower right of the local evaporation line, indicating that the lake region has the highest evaporation. Part of the δ18O-δD river-groundwater relationship point falls above the local atmospheric precipitation line, suggesting that the local atmospheric precipitation may not be the primary source of groundwater replenishment. The water of Dali Lake is uniformly mixed, with δD, δ18O, and the volume of lake water remaining relatively stable, which satisfies the applicable conditions of the stable isotope mass balance method. The stable isotope mass balance method was used to estimate the evaporation and recharge of groundwater from Dali Lake on an annual basis. The evaporation volume was about 269 million m3, and the annual groundwater recharge was about 165 million m3. The groundwater supply accounts for about 61% of the total supply of Dali Lake and is its main supply source. Using the relationship between δD and the residual water mass in the process of stable isotopic fractionation of the water mass, and taking into account the dynamic fraction and the initial isotopic composition of the water mass, the loss by evaporation of Dali Lake was calculated to be about 41%-46% of the initial water body. These results indicate that groundwater is an important source of recharge for river water. Figures and Tables | References | Related Articles | Metrics

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Study on temporal and spatial variation characteristics and influencing factors of hydraulic erosion in the middle of the northern slope of Tianshan Mountains based on CSLE model CHANG Mengdi,WANG Xinjun,LI Na,YAN Linan,MA Ke,LI Juyan 2021, 38 (4):  939-949.  doi: 10.13866/j.azr.2021.04.05 Abstract ( 488 )   HTML ( 12 )   PDF (6644KB) ( 232 )   It is of great significance to ecological early warning and soil erosion prevention on mastering the spatial law and driving force of soil water erosion differentiation on the northern slope of Tianshan Mountains, which could provide theoretical basis and data support for comprehensive management of regional ecological environment on the northern slope of Tianshan Mountains. Taking the mountainous area in the middle of the northern slope of Tianshan Mountains as an example, the temporal and spatial pattern characteristics (area, intensity and geographical distribution) of soil hydraulic erosion in the study area from 2000 to 2018 were quantitatively analyzed by means of field investigation, geographic information system, mathematical statistics and geographic detectors, and the internal driving forces of rainfall, topography, soil and vegetation on soil hydraulic erosion intensity were explored by means of geographic detectors based on the Chinese soil loss equation (CSLE). The results showed that: (1) From 2000 to 2018, the intensity of soil hydraulic erosion in the middle of the northern slope of Tianshan Mountains was mainly slight erosion and mild erosion, accounting for 32.34%-40.87% and 33.36%-43.01% of the total area respectively. In recent 20 years, the area of slight and light erosion had a downward trend (-26.70, -77.47 km2·a-1), while the area of other erosion intensities had an upward trend (22.10-30.96 km2·a-1), and the overall soil hydraulic erosion intensity was in an increasing trend. (2) The overall soil erosion modulus was Urumqi > Changji City > Fukang City > Hutubi County > Manas County > Shawan County > Shihezi City. The spatial distribution of erosion intensity in the middle of the northern slope of the Tianshan Mountains was closely related to rainfall, topography, soil, and vegetation. The soil types were brown calcareous soil, grass felt soil, and chestnut soil. The area with vegetation coverage less than 15%, slope greater than 15° and rainfall in the range of 400-450 mm was a high-risk erosion area. (3) The magnitude of the differentiation was measured by the q value in the factor detector. The greater the q value, the stronger the explanatory power of the influencing factor to the spatial distribution of soil erosion, the rainfall (0.49) > soil type (0.17) > slope (0.11) > vegetation coverage (0.10). Different influencing factors obviously enhanced the spatial heterogeneity of soil erosion through interaction, and the coupling effect of vegetation coverage and rainfall factors made the q value increase greatly. It is of great significance to determine the key control areas of soil erosion for comprehensive soil erosion prevention and control. Figures and Tables | References | Related Articles | Metrics

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Dynamic evaluation of the risk of the spring snowmelt flood in Xinjiang ZHOU Gang,CUI Manyi,LI Zhe,ZHANG Shiqiang 2021, 38 (4):  950-960.  doi: 10.13866/j.azr.2021.04.06 Abstract ( 436 )   HTML ( 11 )   PDF (6996KB) ( 487 )   Xinjiang is an area with abundant snow and frequent snowmelt floods. In the context of global climate change, the frequency of flood disasters in Xinjiang, especially snowmelt floods, has increased, and flood losses have increased. Based on the mechanism of the spring snowmelt flood in Xinjiang, this study investigates snow depth, elevation, and water system distance, combined with historical disaster data, and uses an objective information model and geographical information system technology on the risk of Xinjiang spring snowmelt flood disasters. A quantitative evaluation was conducted, and a zoning map of the risk of snowmelt flood in Xinjiang in spring was obtained. Furthermore, the dynamic hazard factors of daily positive accumulated temperature and daily precipitation were used to determine static Xinjiang spring snowmelt flood risk zoning, and a dynamic evaluation system of spring snowmelt flood risk was established, which dynamically analyzes the daily occurrence of spring snowmelt floods in Xinjiang. We found that the high-risk areas of spring snowmelt floods in Xinjiang are primarily distributed in the Ili River Valley, Bozhou, the northern slope of the middle Tianshan Mountain, the northern part of Tacheng, and the Altay region in northern Xinjiang. Additionally, the dynamic evaluation test of the snowmelt flood disaster in the Ili area of Xinjiang in mid-to-early March 2005 found that the accuracy of the dynamic evaluation result of the snowmelt flood risk was high, and it can be applied to the dynamic evaluation of snowmelt floods in Xinjiang. This study provides support for the prevention and control of spring snowmelt floods and water resource management in Xinjiang. Figures and Tables | References | Related Articles | Metrics

Soil Resources

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Seasonal variation characteristics of different types of biological soil crust-soil system respiration in Mu Us Sandy Land WANG Rongnv 2021, 38 (4):  961-972.  doi: 10.13866/j.azr.2021.04.07 Abstract ( 472 )   HTML ( 9 )   PDF (4528KB) ( 381 )   Biological soil crust is an important type of surface cover in arid and semi-arid areas, and it is an important component of the carbon cycle in desert ecosystems. However, research on seasonal changes in biological soil crust-soil system respiration is still very scarce, and it is difficult to accurately assess the carbon cycle processes of desert ecosystems over time. We examined the well-developed moss crust and algae crust in the southwest of Mu Us Sandy land in 2018, and we used moving sand as a control. The soil carbon flux measurement system was used to observe the daily dynamics of respiration of the biological soil crust-soil system in different seasons. The relationship between biological soil crust-soil system respiration and environmental factors was explored, and the effects of seasonal changes on biological soil crust-soil CO2 release and temperature sensitivity were analyzed. The results showed that there was a single peak in the biological soil crust-soil system respiration rate in different seasons, but the timing of the peak varied. The peak time of different types of biological soil crust-soil system respiration rates in spring and summer was 13:00, but in winter and autumn, the algae crust-soil system and moving sand respiration rate appeared around 15:00, lagging behind spring and summer by 2 h. In the same season, different types of biological soil crust-soil systems released different amounts of CO2: moss crust>algae crust>moving sand (P<0.05). With the change of season, the amount of CO2 released by the biological soil crust-soil systems first increased and then decreased, and the pattern mainly manifested as: summer>spring>autumn>winter (P<0.05). By analyzing the principal components of the biological soil crust-soil system respiration rate and environmental factors, we found that compared with the 5 cm temperature, the 2 cm soil temperature was the primary influencing factor of biological soil crust-soil system respiration in different seasons. The relationship between the biological soil crust-soil system respiration rate and the 2 cm soil temperature in different seasons showed a good fit with the exponential model. Based on this function, the temperature sensitivity of respiration was calculated. It was found that the temperature sensitivity varied from 1.33 to 3.85. With the change in seasons, the temperature sensitivity first decreased and then increased: winter>autumn>spring>summer. Therefore, the higher the temperature, the lower the temperature sensitivity of the biological soil crust-soil system respiration. Figures and Tables | References | Related Articles | Metrics

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Effects on soil aggregate composition and stability under various fertilization regimes of defective forest land in a sandy soil area ZHANG Lu,MENG Tingting,HU Ya,WEI Jing 2021, 38 (4):  973-979.  doi: 10.13866/j.azr.2021.04.08 Abstract ( 298 )   HTML ( 5 )   PDF (1885KB) ( 176 )   To evaluate the stability of soil aggregates in cultivated land improvements in sandy soil areas, an experimental field was set up in the remnant forest land improvement project area of Jingbian County, Yulin, northern Shaanxi, China. The orthogonal experiment scheme [L9(34)] was used to analyze the effects of different fertilizer types and application rates on soil aggregates. The results showed that compared to non-fertilized farmland soil, the combined application of N fertilizer and organic fertilizer can increase the content of water-stable macro-aggregates. Among them, the content of water-stable macro-aggregates larger than 2 mm was relatively higher when applying the T7 treatment (421.34 kg·hm-2 urea, no P fertilizer, 125 kg·hm-2 potassium chloride, and 7.5 t·hm-2 organic fertilizer) than T1 (no N, P, or K fertilizer, and organic fertilizer), T2 (no N fertilizer, 333.33 kg·hm-2 superphosphate, 62 kg·hm-2 potassium chloride, 7.5 t·hm-2 organic fertilizer), and T3 (no N fertilizer, 675 kg·hm-2 superphosphate, 125 kg·hm-2 potassium chloride, 15 t·hm-2 organic fertilizer). The contents of macro-aggregates over 2 mm were 470.15%, 360.24% and 210.57%, respectively. The quantity distributions when the cumulative content of soil aggregates were 10%, 30%, 60% were D10, D30, D60, respectively. The mean weight diameter, geometric mean diameter, and the soil structure coefficient all had a significant influence, with water-stable large aggregates >2 mm and 0.25-2 mm having obvious promoting effects. The soil structure coefficient (Kctp) of T3, T4 (198.28 kg·hm -2 urea, no P fertilizer, 62 kg·hm-2 potassium chloride, and 15 t·hm-2 organic fertilizer), T5 (198.28 kg·hm-2 urea, 333.33 kg·hm-2 super phosphate, 125 kg·hm-2 potassium chloride, no organic fertilizer), T6 (198.28 kg·hm-2 urea, 675 kg·hm-2 superphosphate, no K fertilizer, 7.5 t·hm-2 organic fertilizer), T7 and T8 (421.34 kg·hm-2 urea, 333.33 kg·hm-2 superphosphate, no K fertilizer, and 15 t·hm-2 organic fertilizer) were between 1.5 and 0.67, with a good soil structure. In summary, the combined application of N fertilizer and organic fertilizer, especially with the urea application rate of 421.34 kg·hm-2 (basic application 60%, topdressing 40%), the potassium chloride application rate of 125 kg·hm-2, and the organic fertilizer application rate of 7.5 t·hm-2 can improve newly added forest land. The structure of arable soil aggregates enhances the resistance of soil aggregates to water erosion. Figures and Tables | References | Related Articles | Metrics

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Soil nutrient evaluation of cotton field based on distance clustering and K-means dynamic clustering FAN Xianglong,LYU Xin,ZHANG Ze,GAO Pan,ZHANG Qiang,YIN Caixia,YI Xiang 2021, 38 (4):  980-989.  doi: 10.13866/j.azr.2021.04.09 Abstract ( 398 )   HTML ( 7 )   PDF (1345KB) ( 367 )   This study used principal component analysis combined with distance clustering, K-means dynamic clustering, and comprehensive soil nutrient evaluation methods to analyze and evaluate the soil nutrient status of cotton field soil in Xinjiang, China. The results showed that the available copper, manganese, and alkali hydrolyzable nitrogen played a major role principal component analysis: The available copper content was high (1.82 mg·kg-1); the available manganese content was low (11.36 mg·kg-1); and the alkali hydrolyzable nitrogen content was 122.07 mg·kg-1. The available phosphorus, potassium, zinc and iron contents were low. Thus, the distribution of soil nutrients was uneven. In the distance clustering and K-means dynamic clustering, the organic matter, available nitrogen, and available manganese contents were lower, whereas the other nutrient contents were higher. In the distance cluster, the soil nutrients could be expressed as: class I > class V > class IV > class II > class III, whereas the soil nutrients could be expressed in the K-means dynamic cluster as: class III > class I > class V > class II > class IV. In the comprehensive evaluation of soil nutrients (IFI), the grades of 1 and 16 are higher. The second company, third company, fourth company, sixth company, 15th company, 19th company, and the second prison area had higher levels, whereas the 8th, 9th, 10th, 11th, 12th, 17th, 18th and 20th companies were in the middle level. The grades of companies 5, 7, and 1 supervision district and agricultural city station were lower. Thus, K-means dynamic clustering is better than distance clustering, as it can be more scientific, reasonable, accurate, and effective for the comprehensive evaluation of soil nutrients. Figures and Tables | References | Related Articles | Metrics

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Effects of land use types on the stoichiometric characteristics of soil C:N:P and the physical and chemical properties of soil in western Shanxi loess region HU Yawei,SUN Ruoxiu,SHEN Mingshuang,SHI Zhengle,LIU Chang,XU Qintao,LIU Junting,ZHANG Jianjun 2021, 38 (4):  990-999.  doi: 10.13866/j.azr.2021.04.10 Abstract ( 387 )   HTML ( 7 )   PDF (9174KB) ( 247 )   The aim of this study was to illustrate the effect of different types of land use on the physical and chemical properties of soil, as well as the influence of the ecological characteristics of chemical measurements in western Shanxi loess region, China. The study area included typical artificial mixed forests, Robinia pseudoacacia pure forests, economic forest lands, farmland, and grassland. Specifically, soil layers of 0-10 cm, 10-20 cm, 20-30 cm, 30-40 cm, 40-50 cm, and 50-60 cm were measured for soil bulk density, porosity, organic matter (TC), total nitrogen (TN), total phosphorus (TP) content, analysis of land use, soil physical and chemical properties, and the relationship between the ecological characteristics of chemical metrology to provide a basis for the rational use of land resources and ecological service functions. The bulk density (1.17 g·cm -3, 1.19 g·cm-3, 1.20 g·cm-3) of artificial mixed forest land, Robinia pseudoacacia pure forest, and economic forest land were significantly lower than that of cropland (1.31 g·cm -3) and wasteland (1.38 g·cm-3). The contents of TC and TN in Robinia pseudoacacia pure forest were the highest (9.94 g·kg -1, 0.88 g·kg-1, respectively), while those in the cropland were the lowest (7.26 g·kg-1, 0.63 g·kg-1, respectively), but TP showed no difference (P>0.05). Increased soil depth resulted in gradually increasing bulk density, gradually decreasing porosity, gradually decreasing TC and TN, and a relatively stable TP. The C:P (25.69, 20.51, 19.41) and N:P (2.23, 1.82, 1.58) of artificial mixed forest land, Robinia pseudoacinia pure forest land, and economic forest land, respectively, were higher than those of farmland (18.57, 1.62, respectively). The C:P and N:P decreased with increasing soil depth, but C:N remained stable. C:N was positively correlated with total porosity (P<0.05). C:P and N:P were significantly negatively correlated with soil bulk density (P<0.01), and significantly positively correlated with total porosity, non-capillary porosity, TC, TN, and C:N (P<0.05). The soil nutrient status of the forest land was significantly higher than that of the farmland, with the best effect found in the artificial mixed forest land. The conversion of cultivated land to forest improved soil quality. Thus, when returning cultivated land to forest and grassland, more attention should be paid to the collocation of tree species, instead of creating a single species forest over a large area. Figures and Tables | References | Related Articles | Metrics

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Study on the change of surface CO2 flux in sandy loamy soil under different land use types: An example from the Qingliangsi ditch watershed XU Zhiping,SHAO Tianjie,ZHANG Liankai,SHAO Mingyu,NIU Junjie 2021, 38 (4):  1000-1009.  doi: 10.13866/j.azr.2021.04.11 Abstract ( 440 )   HTML ( 4 )   PDF (4054KB) ( 240 )   Global climate change is closely related to the carbon cycle, and exploring changes in surface carbon emissions is an essential aspect of climate change research. In this study, the CO2 fluxes of surface soils in Qingliangsigou watershed of Loess Hills and Gullies in northwest Shanxi were measured using an LI-8100A soil carbon flux automatic measurement system, the soil particle size was measured using a laser particle size analyzer (mastersizer 2000), the soil organic matter was measured using a chemical titration method, and the soil water content was measured using the drying method. Additionally, we explored the diurnal and spatial variation of surface soil CO2 fluxes, temporal and spatial changes, CO2 fluxes under different land use types, and the influence of environmental factors on surface soil CO2 fluxes to complement the study of surface soil CO2 fluxes in small watershed areas in the Loess Hills and Gullies of northwest Shanxi. We found that CO2 fluxes showed a single peak in variation during the growing season, reaching a single day minimum around sunrise and a single day maximum between 16:00 and 22:00, and in the non-growing season, there was irregular variation. The CO2 fluxes of farmland were lower than the CO2 fluxes of waste grassland and jujube forest land. The highest CO2 fluxes were observed in August, followed by May, and the lowest CO2 flux was in November. The CO2 flux of surface soil was closely related to photosynthetic effective radiation, atmospheric temperature, soil temperature, soil water content, soil organic matter, and soil texture. Therefore, the carbon fixation of soil can be effectively improved through scientific land use. In conclusion, the results of this study can be applied to most of the Loess Plateau and used to improve the ecological environment. Figures and Tables | References | Related Articles | Metrics

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Effect of drip irrigation under mulch combined with drainage by concealed pipes on soil leaching in Xinjiang WANG Dongwang,WANG Zhenhua,CHEN Lin,LI Wenhao 2021, 38 (4):  1010-1019.  doi: 10.13866/j.azr.2021.04.12 Abstract ( 406 )   HTML ( 3 )   PDF (5677KB) ( 378 )   Drip irrigation under film combined with subsurface drainage technology is a type of composite water-saving irrigation and drainage technology. We conducted field experiments in the Anjihai area of 141 production and construction corporations of Xinjiang using three different treatments to study the effect of the technology of drip irrigation under mulch combined with the drainage of underground pipes on the soil leaching effect: Drip irrigation under mulch combined with the drainage of underground pipes (T1), drip irrigation under mulch without the drainage of underground pipes (T2), and drip irrigation without the drainage of underground pipes (T3). We found that under the same soil layer, the changes in the soil moisture content of T1, T2, and T3 treatments were 6.32%, 10.03%, and 14.32%, respectively, which indicated that the T1 treatment could better maintain the stability of soil moisture than the T2 and T3 treatments, and the soil water conservation effect of different treatments was T1>T2>T3. The soil salt content of the 0-60 cm soil layer decreased in the T1 treatment, and it was 63.06%, 60.62%, and 48.42% in the 20 cm, 40 cm, and 60 cm soil layers, respectively. The soil salt content of the 20 cm and 40 cm soil layers decreased in the T2 treatment, but it increased in the 60 cm soil layer, indicating that desalination of the surface soil caused salt accumulation in the deep soil layer, and the surface salt returned in the T3 treatment, at the end of growth period. At the end of the cotton-growing period, the content of soil organic matter increased in the 20 cm, 40 cm, and 60 cm soil layers, but it decreased in the T2 and T3 soil layers without concealed pipes. With the increase in soil depth, the permeability of the soil improved within 0-60 cm. The pH and salt content of the water discharged by the concealed pipe were higher than that of the irrigation water, which indicates that the concealed pipe drained away the salt in the soil at the same time, which is helpful for the improvement of soil salinity and alkalinity. The study provides a theoretical basis for the improvement and management of saline, alkali land in Xinjiang. Figures and Tables | References | Related Articles | Metrics

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The relationship between ECa of sulfate saline soil and moisture content, salt content, and particle size ZHOU Linhu,WANG Haoyu,ZHANG Binglai,QI Zhaoxin,CAO Rongtai,FAN Yanbin,SUN Shenhai,LIU Yuping 2021, 38 (4):  1020-1030.  doi: 10.13866/j.azr.2021.04.13 Abstract ( 587 )   HTML ( 9 )   PDF (6297KB) ( 247 )   This study first measured the sulfate saline soil in the Xiaoxigou basin of the Beishan area in the Xining Basin, China. Five groups of soil samples with different particle sizes (<0.075 mm, 0.075-0.1 mm, 0.1-0.25 mm, 0.25-0.5 mm, 0.5-1 mm, and 1-2 mm) were obtained through the screening test. The apparent electrical conductivity (ECa) of the soil samples with different moisture contents, salt contents (Na2SO4), and particle sizes were then tested, and the relationship between ECa and moisture content, salt content, and particle size were analyzed, and the gray correlation degree was obtained using the gray correlation method. The results showed that increased moisture content, salt content, and particle size resulted in an increasing change law for ECa. For example, when the particle size was 0.075-0.1 mm, the salt content was 0.64%, and the moisture content increased from 5% to 25%, ECa increased by 0.99 mS·cm-1, an increase amplitude of 2475%. When the relationship model between ECa, moisture content and salt content was established, it was concluded that under higher moisture contents (greater than 15%), the correlation between ECa and salt content (P<0.05) was significantly higher than that of low moisture content conditions (less than 15%) (P>0.05). For example, when the moisture content was 10% or 20%, and the salt content increased from 3.18% to 12.18%, the increased amplitudes of ECa were 56.41% and 128.91%, respectively, indicating that the sensitivity of salt to ECa under high moisture content conditions was more significant than the low moisture content. The average gray correlation degree between ECa and the moisture content was 0.80, and between ECa and salt content was 0.68. This indicates that the consistency of the development trend between ECa and moisture content was higher than that of the salt content, when the moisture content was 5%-25%, and the salt content was 0.18%-12.18%. These research results have reference value for the evaluation of the electrical conductivity and salinization degree of sulfate saline soil. Figures and Tables | References | Related Articles | Metrics

Weather and Climate

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Evaluation of FY-2F satellite cloud products in Xinjiang LI Shuai,CHEN Yonghang,HOU Xiaogang,WANG Junhai,XU Zhide 2021, 38 (4):  1031-1039.  doi: 10.13866/j.azr.2021.04.14 Abstract ( 390 )   HTML ( 6 )   PDF (8155KB) ( 307 )   Clouds are an important element of weather and climate characteristics: they affect atmospheric movement and the earth’s climate through three mechanisms: radiative forcing, latent heat forcing, and convective forcing. Cloud is also an important parameter of artificial water augmentation, which is of substantial significance to judge precipitation capacity. Total cloud products from satellite observation are suitable for revealing large-scale climate characteristics, and they have advantages in the plateau, desert, ocean, and other areas where data are scarce. Xinjiang is part of the arid area of Northwest China, where weather stations are sparsely distributed and the types of underlying surface are complex. Therefore, it is suited to the use of total cloud cover products inversed from satellite. However, the retrieval of the amount total cloud from satellite data in arid areas with complex underlying surfaces is a challenging task. Based on the hourly data of total cloud cover observed by ground observation stations from June 2015 to May 2016, we compared and evaluated the correlation and consistency between the FY-2F/CTA products and manually observed total cloud cover in Xinjiang region. We found that FY-2F/CTA correlates with the total cloud cover observed on the ground, except in winter in the area north of Tianshan Mountains, including Tianshan Mountains. Additionally, the consistency rate of FY-2F/CTA products in Xinjiang region was 51.5%, and there was little difference in cloud cover among the three regions of Xinjiang, which is higher in summer and autumn but lower in winter in the northern of Tianshan Mountains and lower in spring in southern Xinjiang. The amount of total cloud inverted from satellite data was generally lower than that observed by ground observation stations, especially in southern Xinjiang. Under different cloud cover levels, the consistency rate was inversely proportional to the total cloud cover: the consistency rate was higher under sunny and partly cloudy conditions and lower under cloudy and overcast conditions. Dust reduced the consistency rate of FY-2F/CTA, increased the strong rate, but it has little effect on the identification of cloud and non-cloud. This study provides an important reference for satellite retrieval and the application of total cloud cover in arid areas. Figures and Tables | References | Related Articles | Metrics

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Spatiotemporal characteristics and influencing factors of dust weather in Qaidam Basin in recent 60 years CHEN Jing,GUO Xiaoning,BAI Wenjuan,WEN Xia,YANG Yanhua 2021, 38 (4):  1040-1047.  doi: 10.13866/j.azr.2021.04.15 Abstract ( 491 )   HTML ( 13 )   PDF (7633KB) ( 239 )   This study analyzes the spatial-temporal variation in sand-dust weather and its influencing factors in Qaidam Basin. Meteorological data on blowing sands, floating dusts, sandstorms, temperature, precipitation, and relative humidity were analyzed for 58 years from nine representative stations in Qaidam Basin using the Mann-Kendall test, wavelet analysis, and other statistical methods. According to the results, the number of days of blowing sands, floating dusts, and sandstorms in the region over the past 58 years has dropped significantly, with the number of days with sand-dust weather being highest in the 1970s and lowest in the 2000s. The number of days of sand-blowing changed abruptly in 1997 and showed a downward trend after the sudden change. The number of sandstorm days had a long period of 10-15 years and a short period of 5-7 years, the number of blowing sand days also had a long period of 10-15 year, and the number of floating dust days had no evident periodicity. There was more sand-dust weather in the southwest of the basin and less in the northeast of the basin. The number of days of blowing sands, floating dusts, and sandstorms were positively correlated with air pressure, gale days, and area and intensity of polar eddies in Asia, and they were negatively correlated with temperature and area and intensity of subtropical highs in the Western Pacific, Tibetan Plateau, Indo-Burma Trough, and Indian Ocean warm pool. Figures and Tables | References | Related Articles | Metrics

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Statistical characteristics of raindrop size distribution and its Z-R relationship for different precipitation clouds in summer in the Qilian Mountains ZHANG Yuxin,HAN Huibang,GUO Shiyu,TIAN Jianbing,TANG Wentin 2021, 38 (4):  1048-1057.  doi: 10.13866/j.azr.2021.04.16 Abstract ( 389 )   HTML ( 6 )   PDF (5414KB) ( 443 )   The microphysical characteristics, raindrop spectrum distribution, particle falling velocity, and Z-R relationship of the precipitation particle spectrum in different precipitation cloud systems (stratiform cloud and convective cloud) in the southern foothold of Qilian Mountains were analyzed using laser raindrop spectrometer observation data from August to September of 2019. The results show that the microphysical parameters of convective cloud precipitation in summer in the Qilian Mountains were all larger than those of stratiform cloud precipitation, and the different stages of convective cloud development had a substantial influence on the rain intensity and microphysical parameters of raindrops. The actual raindrop distribution in summer was most similar to a Gamma distribution in Qilian Mountain, but both an M-P distribution and Gamma distribution led to the overestimation of raindrop concentration. The falling velocities of raindrops at different scales were different, and at the same scale, the range of particle velocities in convective cloud precipitation was slightly larger than that in stratiform cloud precipitation. The fitting curves of traditional particle velocities were underestimated. The Z-R relationship of summer stratiform cloud precipitation in the Qilian Mountain was Z=445R 1.50 and that of convective cloud precipitation was Z=427R 1.88. The traditional radar precipitation estimation method underestimated precipitation in this area. Figures and Tables | References | Related Articles | Metrics

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Sand environment and type during sandy desertification of an alpine meadow AN Zhishan,SHI Boyuan,TAN Lihai,ZHANG Kai,ZHANG Kecun 2021, 38 (4):  1058-1064.  doi: 10.13866/j.azr.2021.04.17 Abstract ( 353 )   HTML ( 11 )   PDF (3324KB) ( 247 )   Alpine meadow desertification in Maqu County is a typical case of desertification in the alpine and humid regions of China. The causes, trends, and management of desertification have received considerable attention; however, due to the limitations of research methods and other factors, the precise positioning of sand sources is still unclear. Here, we combined a three-dimensional laser scanner with traditional methods, such as field surveys and indoor analysis, to locate sand sources accurately from a morphological perspective. The results showed that the regional annual sand drift potential was 164.34 VU, synthetic sand transport potential was 91.57 VU, synthetic sand transport direction was 132.37°, and wind direction variability was 0.56, which belonged to a medium-ratio low wind energy environment. According to the complexity of the contribution of regional sand material, this paper further subdivides the sandy zone along the Yellow River into two types: blowout desertification and complex desertification. The blowout desertification was characterized by isolated sand dunes with a slightly smaller area and wind erosion blowout in the upwind direction. The long axis direction was highly consistent with the regional main wind direction, the length ratio of the wind erosion area and sand accumulation area, volume and other morphological parameters, and the special diagnosis of sand material particle size. The desertification process was relatively simple. Also, the sand material mainly came from wind erosion blowout. The complex desertification area was larger than the blowout desertification area. The causes of desertification include dune activation, regional wind erosion, thermal melt slump. The sources of dune material include surrounding activated dunes, wind erosion land, desertified grassland. Compared with the former, the sand source of complex desertification was relatively wide, and the desertification process was complex and diverse. In modern desertification, the wind-eroded depressions around the region were still the main contributors of sand accumulation in the complex desertification type. At the same time, the Yellow River also provides some amount of sand material for regional desertification. Figures and Tables | References | Related Articles | Metrics

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Phenology of forest vegetation and its response to climate change in the Qinling Mountains YANG Qi,LI Shuheng,LI Jiahao,WANG Jiachuan 2021, 38 (4):  1065-1074.  doi: 10.13866/j.azr.2021.04.18 Abstract ( 485 )   HTML ( 17 )   PDF (5491KB) ( 358 )   It is important to investigate the vegetation phenology pattern and the driving mechanism of vegetation phenology change in a mountain transition zone. In this study, we used the double logistic curve fitting method to extract the phenological parameters of forest vegetation in the Qinling Mountains on the basis of the moderate resolution imaging spectro radiometer and normalized difference vegetation index time-series images from 2000 to 2018. Combining temperature and precipitation data, we performed trend analysis, correlation analysis, and redundancy analysis to study the characteristics of time and space changes in different phenological periods and the response to climate elements in the Qinling area. The following results were obtained: (1) The start and end of the growing season ranged from 60 days to 102 days and from 315 days to 345 days, respectively. The length of the growth season ranged from 225 days to 255 days. From a spatial perspective, it has evident vertical zone distribution characteristics. With an increase in altitude, the start, end, and growth periods of phenology were delayed, advanced, and shortened, respectively. (2) The beginning of phenology was advanced, whereas the end of phenology was postponed. The proportions of pixels in advance and delayed phenologies were 62.25% and 53.42%, respectively. The length of the growing season exhibited a lengthened trend of 59.18%. Of the significantly extended area, 5.12% area was mainly located in the middle and high altitude areas of the central and eastern regions. (3) The initial period of vegetation phenology was negatively correlated with the average temperature and precipitation from February to May, accounting for 50.29% and 65.24% of the total area, respectively. The end of phenology was positively correlated with the average temperature and precipitation from August to November, accounting for 66.63% and 59.77% of the total area, respectively. (4) Redundancy analysis results show that the vegetation phenology in the Qinling Mountains was affected by both the current season and the earlier period of meteorological factors. The spring phenology was more affected in the phenology occurrence period than in the winter of previous year. Compared with autumn weather factors, temperature and precipitation in the early period of phenology exhibit a more significant relationship with the end of phenology. The phenological changes of different slopes exhibit different responses to meteorological factors. Figures and Tables | References | Related Articles | Metrics

Plant and Plant Physiology

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The status of natural vegetation water demand in the Kezi River Basin in recent over 28 years LI Li,ZHANG Qingqing,LI Hong,WANG Yamei,ZHAO Xinfeng 2021, 38 (4):  1075-1084.  doi: 10.13866/j.azr.2021.04.19 Abstract ( 303 )   HTML ( 4 )   PDF (7588KB) ( 221 )   The natural vegetation of the Kezi River Basin is essential to the ecological environment, economic development, and social benefits of the entire region. The dynamic changes in time and space of the natural vegetation in the Kezi River Basin in 1990, 2000, 2010, and 2018 were analyzed using Lansat TM images and annual statistical data of the watershed. Using diving evapotranspiration, the ecological water demand of natural vegetation in the basin was calculated during these four periods. Then, the author combined the research results of the predecessors to determine the limit buried depth of natural vegetation evaporation in the Kezi River Basin, which is the lowest groundwater level that can meet the ecological water requirements of the natural vegetation in the Kezi River Basin, and the amount of water that needs to be restored. We found that between 1990 and 2018, the area of natural vegetation in the Kezi River Basin reduced by 1612.48 km2. The overall reduction over the 28 years was 18.99%, and the total vegetation coverage also decreased by 22.26%. Additionally, the water demand of natural vegetation in the Kezi River Basin during the four periods was 7.69×108 m3, 7.49×108 m3, 6.65×108 m3, and 5.84×108 m3, respectively. During the four periods, the vegetation types with the highest water requirements for natural vegetation in the basin were medium-covered grasslands, and the ecological water requirements were 3.59×108 m3, 3.63×108 m3, 2.92×108 m3, and 2.42×108 m3, respectively. The vegetation with the lowest water requirement were sparse forest land, and the water requirements in the four periods were 0.19×108 m3, 0.19×108 m3, 0.18×108 m3, and 0.17×108 m3, respectively. The water requirements of natural vegetation in the Kezi River Basin in 1990 and 2010 were 16.48% and 8. 13%, respectively, and they were zero in both 2000 and 2018. In the four periods, the inflow of water in the basin could not fully meet the ecological water demand of natural vegetation, and the water shortages were 6.65×108 m3, 7.49×108 m3, 6.11×108 m3, and 5.84×108 m3, respectively, which shows that water shortage in the basin has been severe. The phreatic evaporation limit groundwater depth was estimated as 5.5 m to ensure the ecological water demand of natural vegetation. Based on the current data, the water required to restore the groundwater depth to 5.5 m is 9.73×108 m3. Figures and Tables | References | Related Articles | Metrics

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Simulation of vegetation change based on BP-SVM mode JIA Songtao,HUANG Shengzhi,WANG Hao,LI Ziyan,HUANG Qiang,LIANG Hao 2021, 38 (4):  1085-1093.  doi: 10.13866/j.azr.2021.04.20 Abstract ( 377 )   HTML ( 10 )   PDF (3801KB) ( 346 )   Vegetation is an important link that connects the biosphere, atmosphere and hydrosphere, and has an important impact on the watershed in the ecological environment and on the exchange of water and heat. Previous studies focused on correlation analyses between the normalized difference vegetation index (NDVI) and climate factors, but the lag and the increase of forecast factors were rarely used to improve the precision of the NDVI model. Thus, this article compared the prediction performance of the multiple linear regression, artificial neural network and support vector machine, then selected the model with the highest precision. Using conventional factors (rainfall and temperature), the prediction performance was tested when soil moisture and sunshine duration were increased, which affect vegetation growth, and the time lag effect between the different factors and NDVI were considered. (1) SVM had the strongest fitting ability and the highest NDVI prediction accuracy. The root-mean-square error of the Jing River Basin and the Beiluo River Basin were reduced by more than 1.8%. (2) The root-mean-square error (RMSE) of Jing River Basin decreased by up to 8.8% when soil moisture, sunshine and other factors were added. (3) Considering the lag time, the root-mean-square error of the Jing River Basin and the Beiluo River Basin decreased by 15% and 11%, respectively, and the predicting accuracy of NDVI was improved further, thus increasing the reliability of the model. These prediction results have an important reference significance for the formulation of ecological protection strategies and the guidance of ecological restoration in the future. Figures and Tables | References | Related Articles | Metrics

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Influence on stoichiometric characteristics during the growth period of Salsola subcrassa M. Pop. under different precipitation frequencies SUN Jing,REN Wen,DU Lan,ZHENG Xinjun,LI Yan,ZHAO Jin 2021, 38 (4):  1094-1103.  doi: 10.13866/j.azr.2021.04.21 Abstract ( 352 )   HTML ( 5 )   PDF (6335KB) ( 173 )   In this study, the stoichiometric characteristics in plant organs and the construction of nutrient transmission pathways were studied under changing precipitation patterns to better significance to the survival of native plants. Four treatmentswere tested: Once a month by 20 mm rainfall(W1); twice a month with 10 mm rainfall each time(W2); and 4 times a month with 5 mm rainfall each time(W4) and natural precipitation(CK). We explored thestoichiometric characteristics of leaves, stems and fruitsof S. subcrassa, and also determined differences in its neutral detergent fiber(NDF), acid detergent fiber(ADF)and acid detergent lignin(ADL). The results showed that the N content in the leaves and fruits decreased under each treatments as the plant grew, but increased in stems. Compared with CK, the W4 increased the N contents in the organsduring the growth period; and the P content in the leaves and stems decreased with plant growth, but increased in fruits. The W4 increased the P content in the stems and fruits during the entire period compared to other treatments. Under each treatment, the C:N of the leaves and stems showed a trend of first increasing, then decreasing over time. The C:P and N:P increased, whereas the C:N and C:P in the fruit were stable. The N:P in the fruit decreased. The W4 significantly increased the N:P in the leaves and fruits during the fruit growth period(P˂0.05) compared to the other treatments. Other treatments optimized the nutrient distribution strategy of plant compared to CK. As the plant grew, the NDF, ADFand ADL contents in the leaves and stems increased significantly(P˂0.05); the significant difference was reached in leaves under the same treatment at different stages(P˂0.05). Only W4 increased the ADF content of the stems and fruits during fruit growth. Results indicated that S. subcrassawas more conducive to optimizing nutrient distribution under W4. Figures and Tables | References | Related Articles | Metrics

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Spatiotemporal evolution of vegetation coverage in Alhagi sparsifolia Reserve in Turpan Basin, Xinjiang LI Ziyu,CHENG Qihui,HUANG Feng,GUO Zhentian 2021, 38 (4):  1104-1110.  doi: 10.13866/j.azr.2021.04.22 Abstract ( 505 )   HTML ( 12 )   PDF (2997KB) ( 223 )   It is of substantial significance for ecological and environmental protection to restore vegetation coverage by returning grazing land to grassland. In this study, the regional normalized difference vegetation index (NDVI) data were extracted from Landsat Thematic Mapper (TM)/ Enhanced Thematic Mapper Plus (ETM+)/Operational Land Imager multi-phase remote sensing images, which were selected from July to September of each year from 1996 to 2020. Meanwhile, Fractional Vegetation Coverage (FVC) was calculated by computing the equation of Excess Green minus Excess Red (ExG-ExR). Additionally, the variables in the equation were based on Unmanned Aerial Vehicle images in the early part of August 2019. The best-fit curve between NDVI and FVC was first established based on the above NDVI and FVC data in the same period. Then, two parameters of the pixel binary model were calculated through the fitted curve between NDVI and FVC: NDVI for the pure bare soil pixels and NDVI for the pure vegetation cover pixels. Then, the pixel binary model was used to retrieve the vegetation coverage of the Alhagi sparsifolia reserve in the Turpan Basin from 1996 to 2020. Finally, linear regression analysis was used to investigate the evolution of vegetation coverage in the A.sparsifolia Reserve in the Turpan Basin throughout the study period. The results showed that vegetation coverage increased in the A.sparsifolia Reserve in the Turpan Basin over the past 25 years. The area of the significant improvement area accounted for 20.14% of the total area of the A. sparsifolia Reserve in the Turpan Basin, and the vegetation coverage of the significant improvement area increased from 3.09% to 18.30% over the past 25 years. A.sparsifolia was primarily distributed from western to central regions in the significant improvement area along the tail of the Baiyang River, which empties into the Aiding Lake, its terminal lake, at the lowest altitude of the A.sparsifolia Reserve. The areas in the west and northeast of the A.sparsifolia Reserve, which were close to residential land located in the south of the Flaming Mountains and east of Tuokesun County, also belonged to the significant improvement area. The results of this research provide a scientific reference for selecting the two parameters of the pixel binary model and a scientific basis for ecological environment management and protection of the Turpan Basin in Xinjiang. Figures and Tables | References | Related Articles | Metrics

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Deformation characteristics of the straight roots of Amorpha fruticosa BAI Luyi,LIU Jing,HU Jinghua,ZHANG Xin,LI Shiwen 2021, 38 (4):  1111-1119.  doi: 10.13866/j.azr.2021.04.23 Abstract ( 539 )   HTML ( 6 )   PDF (6805KB) ( 419 )   The strength characteristics, constitutive relation, and elastic deformation characteristics of the straight roots of Amorpha fruticose, with diameters of 1-5 mm, were measured using a TY8000 servo control testing machine to clarify the mechanical properties of the materials of the plant roots under axial or radial loads. We found that the limit force was negatively correlated and limit strength was positively correlated with root diameter as a power function. When the stress-strain curve (σ-ε curve) was calculated from elastic deformation to plastic deformation under two type loads, there was no significant difference between the ultimate stress and elastic stress of straight roots, but the ultimate strain (15.04%) and elastic strain (2.71%) under axial load were significantly smaller than the radial load (20.39%, 4.19%). The tensile modulus and bending modulus were negatively correlated with root diameter as a power function, and the tensile stiffness and bending stiffness were positively correlated with root diameter as a power function. The percentage of the average elastic stress to the ultimate stress under axial load of each diameter level (50.45%) was significantly higher than the radial load (34.08%). Overall, the elastic property of root system is better under an axial load, and Amorpha fruticosais best suited to planting in an area of wind and hydraulic erosion where the primary load type is axial load. Figures and Tables | References | Related Articles | Metrics

Ecology and Environment

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Identification and optimization of ecological corridors in Shenmu City based on landscape ecological security WU Jinhua,LIU Siyu,BAI Shuai 2021, 38 (4):  1120-1127.  doi: 10.13866/j.azr.2021.04.24 Abstract ( 459 )   HTML ( 6 )   PDF (7401KB) ( 127 )   In this study, the ecological security of the Shenmu City landscape was evaluated to optimizing its ecological pattern. Principal component analysis, the natural break point method, and the multivariate curve resolution (MCR) model were used to obtain the distribution of the ecological security pattern in Shenmu City, China. Then, the ecological source area was extracted and the MCR model was used to construct the ecological corridor that optimizes the ecological landscape pattern. The results showed that the landscape security of Shenmu City is divided into five levels: The first level area is mostly located in the northwest, with a few areas distributed in the southeast and the northern marginal areas; the secondary and tertiary regions are distributed in fragmented phases throughout the whole region; due to the impact of human activities and natural conditions, the fourth and fifth level regions are concentrated and distributed in the central construction area, with the southeast gully crisscross area of fragmented distribution. Of the 121 ecological corridors in Shenmu City, 19.08% exist independently, and 43.51% are not connected to the main ecological corridor group. Thus, 10 new ecological corridors were designed, with a total length of 76.69 km to improve the ecological corridor network and strengthen the connection between the independent ecological corridors and the ecological source land. The results of this study are of great significance to optimize the landscape ecological environment of Shenmu City and to construct an ecological security pattern. Figures and Tables | References | Related Articles | Metrics

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Ecological security assessment and ecological restoration countermeasures in the dry-up area of the lower Tarim River KONG Zijie,DENG Mingjiang,LING Hongbo,WANG Guangyan,XU Shengwu,WANG Zengru 2021, 38 (4):  1128-1139.  doi: 10.13866/j.azr.2021.04.25 Abstract ( 443 )   HTML ( 15 )   PDF (9073KB) ( 267 )   Harnessing the ecological environment of the cutoff river in the lower reaches of Tarim River is of great significance for maintaining the overall ecological security of the downstream Tarim River and consolidating the achievements of ecological water conveyance in the past 20 years. The lower reaches of Tarim River have been involved in ecological water conveyance since 2000, and now remarkable achievements have been made. However, ecological degradation in some areas of the lower Tarim River Basin is severe, and its branches, the Karanqi River and Nashen River, are still fragmented. Remote sensing images and meteorological and hydrological data of the river cutoff area combined with GIS technology and Mann-Kendall nonparametric test method were used to analyze the temporal and spatial variation laws of ecological environment elements, to evaluate the ecological security situation, and to propose countermeasures for ecological restoration. The results show that in terms of meteorological elements, the number of sandstorm days increased under the condition of extremely significant reduction of gale days from 1971 to 2019, the temperature and precipitation showed an upward trend from 1957 to 2019, and the temperature-vegetation drought index increased greatly from 2000 to 2018. In terms of the variation law of vegetation factors, although the vegetation coverage and productivity showed no significant increasing trend from 2000 to 2018, their levels were very low. Furthermore, the ecological security of the cutoff river area is in the early and moderate warning levels. Figures and Tables | References | Related Articles | Metrics

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Optimization of land use structure based on ecosystem service value in the mainstream of Tarim river LIN Jing,ZHAO Chengyi,MA Xiaofei,SHI Fengzhi,WU Shixin,ZHU Jian 2021, 38 (4):  1140-1151.  doi: 10.13866/j.azr.2021.04.26 Abstract ( 355 )   HTML ( 9 )   PDF (8252KB) ( 185 )   In this study, the effect mechanism of land use and land cover change (LUCC) on ecosystem service value (ESV) in a complex environment was analyzed, and the land use structure was optimized based on ESV. The results showed that after the implementation of ecological water conveyance (EWC), the average annual variation rates of cultivated land, woodland, grassland, desert, water area in the mainstream of the Tarim River were 7.26%, 2.68%, -1.90%, 1.22% and 0.08%, respectively. The increase of cultivated land and woodland areas were mainly caused by grasslands, and the inflow of EWC increased the water areas. An increasing-decreasing-recovering tendency of time series in ESV with 299 million yuan in the lower reaches of the Tarim River was observed, and showed a decrease over all of the mainstream of Tarim River with 3.96 billion yuan. The water resources were of great significance to the stabilization and improvement of ESV in arid areas. Based on past analysis, the water area had the dominant influence on ESV, with the direct and indirect effects of 0.610 and 0.345, respectively. Based on the relationship between the different land use types, the optimal structure was calculated for the proportion of cultivated land, woodland, grassland, desert and wetland, which were 3.34%, 10.03%, 38.22%, 45.95%, and 0.96%, respectively. In this circumstance, the ESV can reach a maximum of 53.369 billion yuan. With the expansion of cultivated land areas, the contradiction between agricultural water consumption and ecological water utilization becomes more and more serious. It is of great significance to balance the characteristics of land use structure and water consumption for the maintenance of ESV and the rational allocation of water resources, which can provide a basis for exploring the optimal state of man-land relationships in the Tarim River Basin. Figures and Tables | References | Related Articles | Metrics

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Multi-scenario simulation prediction of ecological space in the Fenhe River Basin using the FLUS model SU Yingqing,LIU Geng,ZHAO Jingbo,NIU Junjie,ZHANG Enyue,GUO Ligang,LIN Fei 2021, 38 (4):  1152-1161.  doi: 10.13866/j.azr.2021.04.27 Abstract ( 695 )   HTML ( 15 )   PDF (9565KB) ( 144 )   Multi-scenario simulation and prediction of watershed ecological space was conducted for the Fenhe River Basin to provide reference and guidance for the coordinated and sustainable development of watershed production-living-ecological space. An ecological-economic-social model was used with land use type data for 2015 and 2018, and 20 drivers were selected. The accuracy and effectiveness of the future land use simulation model was verified, and the spatiotemporal evolution characteristics and drivers of ecological change in the Fenhe River Basin were simulated and predicted for 2024 and 2030 under four scenarios: production space priority, living space priority, ecological space priority, and production-living-ecological space coordination. We found that the ecological space of the Fenhe River Basin presented two types of evolution trends from 2018 to 2030. It showed linear growth under the ecological space priority and production-living-ecological space coordination scenarios, with increases of 5.92% and 5.13%, respectively, while there was a linear decrease under the production space priority and living space priority scenarios, with decreases of 9.40% and 2.20%, respectively, and the proportion of production space, living space, and ecological space land structure maintained a ratio of 4:1:5. In the spatiotemporal pattern, the ecological space was located in the marginal mountainous area of the watershed, and the production space and living space were located in the core basin. The ecological space, production space, and living space as a whole present successively nested pattern characteristics. The range of change in the core area of the ecological space was small, and the change in the marginal area was significant. The evolution trend of ecological space under the production-living-ecological space coordination scenario and ecological space priority scenario was similar in 2024 and 2030. Affected by the natural-social development trend of the watershed and national policies, the available reserve land resources are predicted to be limited in the future, and the ecological space change of the watershed is predicted to be small, but there are also hidden threats. Therefore, we suggest strictly following the basic principles of three lines, the permanent basic farmland protection red line, ecological protection red line, and urban development boundary line, reasonably planning the reserve land resources of the production-living-ecological space, actively governing and conserving the ecological space edge areas (ecologically sensitive areas), restricting the development of core areas, and promoting the scientific development of watersheds. Figures and Tables | References | Related Articles | Metrics

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A study of cultivated land utilization efficiency and its influencing factors in Hebei Province based on DEA-Malmquist index ZHAO Qianshi,PAN Peipei,WANG Xiaoxu,WANG Xueran,WANG Xiaomeng,LI Ning,WANG Xinyun 2021, 38 (4):  1162-1171.  doi: 10.13866/j.azr.2021.04.28 Abstract ( 352 )   HTML ( 7 )   PDF (4318KB) ( 336 )   The improvement of arable land use efficiency is of great significance to ensure food security in the main grain production areas, given the rapid non-agriculturalization of arable land brought on by urbanization. This study used the DEA model, the Malmquist index, and the GWR model to analyze the temporal and spatial characteristics, dynamics, and influencing factors of the cultivated land use efficiency in Hebei Province, China from 2000 to 2015 at the county scale. The results showed the comprehensive efficiency, pure technical efficiency, and scale efficiency of arable land use was maintained at a relatively high level of 0.8-1. The comprehensive efficiency of arable land use first decreased from 0.9 to 0.8 by 2003, then had a volatility increase to reach 1 in 2015. From a spatial point of view, the overall efficiency of cultivated land utilization between regions changed significantly, and the regional homogeneity increased. In regards to dynamic changes, the total factor productivity index of arable land use fluctuated from 1.03 to 1.18. The comprehensive improvement of arable land use was mainly distributed in the northern part of the province, whereas the improvement of technological progress was distributed in central and southern Hebei, and the improvement of technological change only existed in the Hengshui City district, and the comprehensive descending type was scattered in the central and southern regions. From the perspective of influencing factors, the comprehensive efficiency of arable land under a certain probability level was positively correlated with the proportion of agricultural output value and the multiple crop index, and was negatively correlated with the elevation, slope, proportion of agricultural population, and proportion of non-grain crops. Among them, elevation, slope, the multiple cropping index, and the proportion of agricultural population had little influence. The proportion of agricultural output value and the proportion of non-grain were more obvious, with the proportion of non-grain having the most significant influence with a correlation coefficient of -0.520249. Based on these results, suggestions are given to improve the arable land use efficiency. Figures and Tables | References | Related Articles | Metrics

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Land coverage change and driving forces of an oasis in the southern margin of Tarim Basin GAO Yuting,YU Yang,SUN Lingxiao,YU Ruide 2021, 38 (4):  1172-1183.  doi: 10.13866/j.azr.2021.04.29 Abstract ( 612 )   HTML ( 18 )   PDF (3928KB) ( 303 )   The characteristics of land use/cover change of the Cele oasis, in the southern margin of Tarim Basin, from 1990 to 2018 were explored and attributed based on four phases of land use and remote sensing images, as well as meteorological, hydrological, and socio-economic data. We found that the land use types in the Cele oasis changed substantially: The farmland area expanded to the surrounding area, the forest land distribution area shifted substantially, and the coverage of grassland changed frequently. Overall, 138.41 km2 (53.85%) of the total area was transformed. In descending order, the single dynamic attitude was high covered grassland>farmland>low cover grassland>construction land>medium covered>grassland unused land>forest land, and in descending order, the double directional trend was high covered grassland>farmland>low cover grassland>construction land>forest land>medium covered>grassland unused land. The results also showed that the vegetation index of the green continent was less than 0, which indicates that forest land and grassland have been in a state of degradation. The driving forces of land use change in the oasis were population, precipitation, and runoff, based on the factors influencing surface cover in the oasis. Figures and Tables | References | Related Articles | Metrics

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Numerical simulation of wind-blown sand flow field and formation mechanism of sand damage on road surface in shifting dune area ZHANG Xingxin,ZHANG Kai,SHI Boyuan,CUI Baohong,ZHAO Liming 2021, 38 (4):  1184-1191.  doi: 10.13866/j.azr.2021.04.30 Abstract ( 470 )   HTML ( 8 )   PDF (5063KB) ( 318 )   This study analyzed the wind-sand flow field of a highway roadbed to reveal the formation mechanism of pavement sand damage, which provides a theoretical basis for the prevention and control of sand damage on a road surface in a shifting dune area. The study area was Highway 303 in Zhongzaohuo, Qinghai Province, China, which was selected based on computation fluid dynamic numerical simulation. The numerical simulation results showed that when the airflow passes through the shifting dune and the roadbed, the airflow velocity is divided into zones. In the presence of a flowing dune, the range of the deceleration zone around the subgrade increased significantly, while the subgrade slope and the leeward slope were all in the low speed airflow zone. On the top of the sand dunes, the air velocity increased sharply and was affected by the shape of the obstacles, which caused the wind speed to change from the “Ω” type to “M” type distribution. When the original sand control system on the dune surface is not maintained and updated, sand grains accumulate in large quantities near the dune. In this manner, the dunes will slowly move in the main wind direction and become the sand source, thus burying the roadbed and causing sand damage. The numerical simulation results are consistent with the actual results obtained, which indicates the accuracy of the numerical simulation. For the prevention and control of road sand damage in the shifting dune area, the local geomorphologic form and the law of wind-sand flow movement should be investigated in detail. Checking and maintaining the original protection system regularly, and cleaning up the accumulated sand in a timely manner will prevent the wind-sand flow from supplying the sand source, and will prevent the sand itself from becoming the sand source. Figures and Tables | References | Related Articles | Metrics

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Effects of Rhombomys opimus disturbance on soil physical and chemical properties of artificial Haloxylon ammodendron forest MENG Ruiling,XU Xianying,WANG Li,LIU Hujun,ZHAO Peng,LI Fengbo 2021, 38 (4):  1192-1198.  doi: 10.13866/j.azr.2021.04.31 Abstract ( 337 )   HTML ( 4 )   PDF (2960KB) ( 157 )   An investigation into the influence of Rhombomys opimus disturbance on the physical and chemical properties of soil could clarify the ecological function and role that R. opimus plays in artificial Haloxylon ammodendron forest. Specifically, the in-use (effective burrows) and abandoned (abandoned burrows) burrows of R. opimus in an artificial H. ammodendron forest were analyzed for the layered determination of 0-30 cm soil moisture, organic matter, total nitrogen, and other parameters to determine how R. opimus excavation activities influence the physical and chemical properties of soil. The results showed that the water content and bulk density of the 0-30 cm layer of soil had the same change laws: Abandoned cave < effective hole < control; and the water content and bulk density increased with increased burrow depth. The salt content in the soil layers in the effective and abandoned burrows decreased with increased soil depth. The pH of each soil layer increased in the effective burrows, but decreased in the abandoned burrows. The total nitrogen in each soil layer (0-10 cm, 10-20 cm, 20-30 cm) in the effective burrows was 0.23 g·kg -1, 0.13 g·kg-1, and 0.22 g·kg-1 higher than in the abandoned burrows. The total phosphorus and total potassium in the soil layers were: Effective burrows > abandoned burrows > control, with the highest content in the 0-10 cm layer. The available phosphorus in the soil layers of both burrows had the same change rule, with the highest content in the 20-30 cm layer. The effective potassium in each soil level in the effective burrows was 1.05, 1.01, and 1.01 times that of the abandoned burrows. Organic matter: The total amount of organic matter in the effective and abandoned burrows increased by 63.2% and 48.8%, respectively. In summary, the soil nutrients of the effective burrows were generally higher than those of the abandoned burrows, and the soil nutrients increased in different degrees, indicating that R. opimus disturbance could change the soil bulk density and water patterns, promote nutrient accumulation, and increase soil fertility. Figures and Tables | References | Related Articles | Metrics