Table of Content

15 November 2018, Volume 35 Issue 6 Previous Issue    Next Issue

Water and Soil Resources

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Effect of Ecological Water Conveyance on Vegetation Coverage in Surrounding Area of the Qingtu Lake ZHAO Jun, YANG Jian-xia, ZHU Guo-feng 2018, 35 (6):  1251-1261.  doi: 10.13866/j.azr.2018.06.01 Abstract ( 933 )   PDF (4142KB) ( 705 )   Ecological water conveyance is an effective way to alleviate ecological problems in the form of human intervention to regenerate the degenerated ecology, and it is applied in the surrounding area of the Qingtu Lake, the tail-end lake of the Shiyang River in Minqin County, Gansu Province. The effect of ecological water conveyance on the ecology and environment in the region has attracted much attention. In this paper, the inversion of vegetation coverage (FVC) was reconstructed using the Landsat images in the surrounding area of the Qingtu Lake during the period from 1987 to 2016. The characteristics of the overall dynamic change of FVC were firstly explored, and then the relationship between such change and the ecological water conveyance was analyzed. The results showed that the average vegetation coverage in the surrounding area of the Qingtu Lake was increased from about 10% to 20% in the past 30 years. The change trend of vegetation coverage before and after 2010 was obviously different. The trend analysis was used to compare the characteristics of vegetation cover before and after the ecological water conveyance in September 2010, and the results showed that the effect of climate change on the vegetation coverage in the study area was slight although climate change was the main factor affecting the large-scale vegetation coverage. The vegetation coverage was mainly increased in the area near the lake, and the ecological water conveyance was the main factor affecting its increase. The change of annual vegetation coverage before the ecological water conveyance in 2010 was not obvious, but after that it was in a significant increase trend. References | Related Articles | Metrics

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Health Assessment of the Yarkant River Based on Harmonious Development Degree Model HE Bing, GAO Fan, TANG Xiao-yu, QIN Shan 2018, 35 (6):  1262-1270.  doi: 10.13866/j.azr.2018.06.02 Abstract ( 898 )   PDF (1627KB) ( 527 )   It is very important for the ecological hydrological conservation and river adaptability management in arid inland river basins to determine and evaluate the factors affecting the river health and its change.The river section from Kaqung to Ayriktam of the Yarkant River was considered to be typical,the river health evaluation index system was set up with 23 indexes based on the pressure state response model,and the river health evaluation standards were put forward.On which the theory of coordinated development degree was introduced for assessing the river health,the river health evaluation model was established based on the coordinated development degree,the standard level of the coordinated development evaluation was established and divided,and the river health in 2015 was evaluated and analyzed.The results revealed that the coordinated development index along the river section Dtotal=0.495,the comprehensive evaluation index Ttotal=0.537,the type of coordinated development belonged to the “slightly uncoordinated type”,and the health status belonged to the “sub-health”level.These revealed that the health of the river was threatened.At the aspect of comprehensive river management in the future,the coordinated development level of stress-state-response factors should be improved,and the corresponding index level under restoration response factors should be dominant. References | Related Articles | Metrics

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Response of Runoff Volume Change to Climate in the Keriya River in Xinjiang WANG Da-wei, SHI Qing-dong, DONG Di-wen, CHEN Chao-jun 2018, 35 (6):  1271-1279.  doi: 10.13866/j.azr.2018.06.03 Abstract ( 8 )   PDF (4021KB) ( 0 )   The characteristics of runoff are crucial for water resources management, water supply planning, environmental protection and ecological regeneration, and the temperature change caused by climate change decreases the stability of surface flow. In this study, the data of runoff volume, air temperature, precipitation and evaporation from Langan Hydrological Station, a management agency of the Keriya River Basin were used to analyze the sources of runoff with the wavelet analysis and M-K mutation test, and the response of runoff volume to temperature and precipitation change was also analyzed. The results showed that: ① In the past 57 years, the runoff volume and air temperature in the Keriya River Basin was in a significant non-linear upward trend, while the increase of precipitation and evaporation was not obvious; ② On the interannual scale, there was an 8 a period of runoff volume in the headwaters, and also a 12 a period of temperature and precipitation change. On the interdecadal scale, there was a 22 year period of runoff volume change, and also a 28 year period of the change of temperature, precipitation and evaporation. Moreover, there was a 22 a period of evaporation change; ③ Runoff volume was affected by both temperature and precipitation. On the interannual scale, runoff volume was positively correlated with precipitation, but negatively with temperature and evaporation. However, on the interdecadal scale, the correlation between runoff volume and air temperature was higher, and the effect of temperature on runoff volume was more significant; ④ In the periodic oscillation, temperature was in accordance with evaporation. The response of runoff volume change to the changes of temperature, precipitation and evaporation was time-lagged, such mode could regulate runoff volume of the Keriya River; ⑤ Compared with the Urumqi River, the mutation of runoff volume of the Keriya River lagged for about 10 years, which was caused by the low temperature in the Keriya River Basin in the 1990s. References | Related Articles | Metrics

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Management Regime in Alpine Meadow Based on the Assessment of Soil and Water Erosion MA Su-jie, JIA Sheng-hai, HUA Li-min 2018, 35 (6):  1280-1289.  doi: 10.13866/j.azr.2018.06.04 Abstract ( 7 )   PDF (2104KB) ( 0 )   In this study,the RUSLE model and the RS and GIS means were used to estimate the soil erosion in 10 years from 2004 to 2014 in Tianzhu County and Hezuo City in Gansu Province,where the household contract system and allied household contract system were separately implemented.The purposes of this study were to compare the grassland management regime in alpine meadow,improve the rangeland management system,and analyze the correlations between the soil erosion and the annual precipitation,farmer population,livestock number and animal husbandry production value.The reasons causing the difference of soil erosion modulus of grassland in two counties were analyzed by exclusion method.The result showed that: ① Slight soil erosion occurred in both Tianzhu County and Hezuo City. ② The average annual modulus of soil erosion in Tianzhu was 7.21 (t·a·km-2) and higher than that in Hezuo City.The increase rate of soil erosion in Tianzhu County was 4 times of that in Hezuo City.The increase of soil erosion modulus of all grassland types in Tianzhu County was higher than that in Hezuo City. ③ There was a significant positive correlation between annual precipitation and soil erosion (R=0.737,P<0.05) in Tianzhu County.In Hezuo,there was a significant negative correlation between farmer population and average rangeland erosion modulus (R=-0.829,P<0.05). ④ There was no correlation between the difference of grassland erosion modulus and the annual precipitation difference in both Tianzhu County and Hezuo City (P>0.05).The livestock overload rate in Hezuo City was higher than that in Tianzhu County.This study suggests that grassland management model is the main reason causing grassland degeneration and soil erosion,and the allied household management regime is superior to the individual household management regime in controlling soil and water erosion. References | Related Articles | Metrics

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Ecological Effects of Condensed Water to Ephemeral Plants Lappula semiglabra in Desert LIU Zhi-dong, RAN Qi-yang, CHEN Yue, QIE Ya-dong, LYU Guang-hui 2018, 35 (6):  1290-1298.  doi: 10.13866/j.azr.2018.06.05 Abstract ( 10 )   PDF (1492KB) ( 0 )   In this study, Lappula semiglabra, an ephemeral plant species and the most sensitive to water conditions in the Ebinur Lake Wetland Nature Reserve, Xinjiang, northwest China, was selected as the research object. Three condensed water gradients, i.e., the group T1 without cover, group T2 treated with semi-covered and group T3 treated with complete cover, were designed. The purposes of the study were to lucubrate the effects of condensed water on the plant height, canopy size, leaf area, leaf thickness, root length, root diameter, leaf relative water content, leaf water potential and biomass allocation of L.semiglabra plant. The results showed that: ① In the late plant growth season, the plant height, canopy size, leaf area, leaf thickness, leaf relative water content, net photosynthetic rate, stomatal conductance and leaf water potential were significantly increased (P<0.05) with the increase of condensed water; on the contrary, there was no significant difference of root length and root diameter among the 3 treatments (P>0.05); ② The stem mass ratio (SMR) was relatively stable in the biomass allocation, and it varied in a range of 3.0%-13.5%. The difference of leaf mass ratio (LMR) among plants was significant (P<0.05), the root mass ratio (RMR) decreased gradually, but there was no significant difference. It could be concluded that the leaves of L.semiglabra in arid area can absorb and utilize condensed water. The morphological characters are highly sensitive to water and have high variability. References | Related Articles | Metrics

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Simulation of Soil Water and Salt Migration Under Open-ditch Drainage LI Kai-ming, LIU Hong-guang, SHI Pei-jun, LI Xin-xin 2018, 35 (6):  1299-1307.  doi: 10.13866/j.azr.2018.06.06 Abstract ( 4 )   PDF (2754KB) ( 0 )   In this study, the change of saline-alkaline soil salinity in 122nd State Farm of Xinjiang Corps of Production & Construction was monitored by controlling field irrigation. The purposes of the study were to explore the soil water and salt migration under the conditions of drip irrigation, plastic film mulching and open-ditch drainage, develop a HYDRUS numerical model, and simulate and analyze the change of soil salinity in cotton growth period. The results showed that the average desalination rate of 0-80 cm soil layer reached 50.09%, the total salinity of 80-200 cm soil layer was basically maintained, and the salinity of 0-200 cm soil layer was decreased by about 25%. The closer the place from the ditch was, the more efficient the soil desalination would be. The values simulated with the numerical model were in a good accordance with the measured values. The research results could be referred in field management in arid and semiarid saline-alkaline areas. References | Related Articles | Metrics

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Spatiotemporal Variation of Moisture Content of Different Soil Types in Desert Steppe SU Ying, CHEN Lin, LI Yue-fei, YANG Xin-guo, ZHANG Yi-fan, YANG Dong-dong, ZHU Lin 2018, 35 (6):  1308-1316.  doi: 10.13866/j.azr.2018.06.07 Abstract ( 5 )   PDF (3922KB) ( 0 )   Three soil types including sandy soil, residual soil of weathered bedrock and sierozem were used to equip a device of controlling rainfall, record soil moisture content by an installed American HOBOU 30, and monitor the long-term dynamic change of soil moisture content. The purposes of this study were to research the spatial and temporal dynamic changes of moisture content of different soil types in desert steppe and its response to precipitation variation. The results showed that the temporal variation of volumetric moisture content of sand soil, residual soil of weathered bedrock and sierozem were affected by rainfall, and three peak values occurred. Rainfall change affected the peak values to appear sooner or later. There were two major types of vertical change of soil volumetric moisture content, i.e. the fluctuation type and reduction type. They were mainly affected by surface vegetation and soil physical properties. The variation coefficients under the normal situation and the rain-reduced treatment of sandy soil and residual soil of weathered bedrock were decreased from the surface to the deeper layer. The variation coefficients of volumetric moisture content of sierozem were 1.21%, 1.36% and 1.46% under the normal situation, rain-increased treatment and rain-reduced treatment respectively. Under the normal situation and rain-increased treatment, the total soil water storage was in an order of residual soil of weathered bedrock>sandy soil>sierozem; under the rain-reduced treatment, however, it was in an order of residual soil of weathered bedrock>sierozem>sandy soil. References | Related Articles | Metrics

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Inversion of Soil Moisture Content in the Shule River Basin GUO Xiao-juan, ZHOU Yan-yan, GUO Jian-jun, CHEN Guan-guang, YUE Dong-xia 2018, 35 (6):  1317-1326.  doi: 10.13866/j.azr.2018.06.08 Abstract ( 2 )   PDF (2354KB) ( 0 )   Soil moisture is an important factor affecting vegetation growth in arid regions. Obtaining soil moisture data at a regional scale can provide a scientific basis for ecological regeneration and conservation of fragile ecosystem in arid and semiarid regions. In this paper, the Apparent Thermal Inertia method and statistical downscaling method were used to obtain the data of soil moisture content at 0-10 cm depth in the Shule River Basin in April, July, October and December 2016 with a 1km resolution based on the Moderate Resolution Imaging Spectroradiometer (MODIS) surface temperature and reflectance data and Global Land Data Assimilation System (GLDAS) soil moisture data. The purposes of the study were to lucubrate the spatiotemporal change of soil moisture content and the correlation between local soil moisture content and vegetation by geographically weighted regression analysis. The results showed that the average annual soil moisture in the Shule River Basin varied in a range of 10-18 mm with an average of 14.11 mm in 2016. Soil moisture content in the Shule River Basin changed significantly in 2016, and the average and discrete degree of soil moisture content was in an order of July>October>April>December. The soil moisture content in the east of the Shule River Basin was higher than that in the west. Soil moisture content was the highest in the upper reaches of the Shule River, three main irrigation areas and near the Mazong Mountain in the north of the basin, but it was the lowest in the Kumtag Desert and Gobi near Aksai-Dunhuang and the upper reaches of the Danghe River. The seasonal variation of spatial distribution pattern of soil moisture content in the basin was significant, and the spatial distribution of variation coefficient was similar to that of average annual soil moisture content. There was a positive correlation between the soil moisture content and the Normalized Difference Vegetation Index (NDVI), but the correlation was different from different regions. It was the highest in the irrigation areas. References | Related Articles | Metrics

Weather and Climate

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Energy Balance During Three Snow Cover Processes at Maqu in the Headwaters of the Yellow River LI Dan-hua, WEN Li-juan, LONG Xiao, CHEN Shi-qiang, LIU Wei-ping, LU Guo-yang 2018, 35 (6):  1327-1335.  doi: 10.13866/j.azr.2018.06.09 Abstract ( 775 )   PDF (2161KB) ( 771 )   In this study, the meteorological data observed at Maqu Station for Climate and Environment Integrated Research, Chinese Academy of Sciences during the period from December 2011 to March 2012 were used. The purposes of the study were to compare and analyze the surface radiation and energy balance in three snow cover processes under the different conditions of soil freezing and thawing as well meteorological conditions in the headwaters of the Yellow River. The results showed that the net radiation was decreased significantly after snowfall, and the net radiations before and after snowfall were 154, 200 and 210 W·m-2 and 93, 129 and 130 W·m-2 respectively. After three times of snowfall and snowmelt, the ground-air energy exchange was strongly affected by weather conditions and soil freezing and thawing: After the first snowfall, the low temperature and land surface temperature did not affect the weak evaporation capacity of frozen soil, the latent heat flux and its difference before and after snowfall and snowmelt were low. On February 18 after second snowfall, the high wind speed (≥4 m·s-1) and strong solar radiation accelerated the sublimation of snow cover, the latent heat flux was high with a daily average of 118 W·m-2, the wind speed and latent heat flux changed synchronously, and their peak values of 15 m·s-1 and 300 W·m-2 occurred simultaneously. The sublimation energy consumption of snow cover reduced the surface temperature and was lower than the air temperature, and a negative sensible heat flux occurred with a daily average of -8 W·m-2 and a peak value of -40 W·m-2. After snowmelt, the latent heat flux and sensible heat flux reached their levels before snowfall. During the period from February 29 to March 3 after the third time of snowfall, the shallow soil temperature was gradually increased from -1 ℃ and maintained at -0.18 ℃, the frozen soil absorbed heat, the increase of latent heat flux was not significant compared with that before snowfall. March 4 was the last day of snowmelt, latent heat was released from damp soil and snowmelt water evaporation, the latent heat flux was increased significantly compared with that on March 3. After snowmelt, the effect of shallow soil evaporation capacity on the latent heat flux was increased significantly compared with that before snowfall. References | Related Articles | Metrics

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Correlation Between Sunspot Activity and Precipitation in the Ankang Region in Recent 63 Years ZHANG Bei-bei, WANG Peng, ZHANG Hui, WU Yue-xuan, WANG Miao-miao 2018, 35 (6):  1336-1343.  doi: 10.13866/j.azr.2018.06.10 Abstract ( 690 )   PDF (2683KB) ( 606 )   In this study, the Mann-Kendall test and Morlet wavelet analysis were used to lucubrate the variation of precipitation and its relationship with the relative number of sunspots in the Ankang region in recent 63 years based on the data of relative annual number of sunspots and daily precipitation observed by Ankang Meteorological Station, Ankang Meteorological Bureau during the period of 1953-2015. The results showed that, in the Ankang region, the annual and summer precipitations were significantly increased with increments of 0.99 mm·a-1 and 1.65 mm·a-1 respectively. The spring, autumn and winter precipitations were decreased slightly with reductions of 0.26 mm·a-1, 0.35 mm·a-1 and 0.06 mm·a-1 respectively. Precipitation occurred mainly in summer and autumn. There was a 0-3 a time lag of the anomaly of extreme precipitation than the occurrence of peak-valley value of relative sunspot number. There were the significant 3 a and 28 a variation periods of annual precipitation in the Ankang region, which was different from the 9 year variation period of relative sunspot number. References | Related Articles | Metrics

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Air Pollution in a Strong Sandstorm in North China JIANG Yu-he, WANG Shi-gong, JIN Shuang-long, FAN Jin 2018, 35 (6):  1344-1351.  doi: 10.13866/j.azr.2018.06.11 Abstract ( 883 )   PDF (3136KB) ( 794 )   In this study, the routine environmental monitoring of pollutant concentration data, NCEP/NCAR 0.5°×0.5° reanalysis data and conventional meteorological observation data were used. The purpose of the study was to lucubrate the air pollution process of a strong sandstorm in 13 provinces (including autonomous regions and municipalities directly under the central government) in China from May 3 to 6, 2017. The results showed that the average daily concentration of PM10 in the main cities suffering from the sandstorm was increased by 2-10 times relative to the monthly average. The average daily concentration of PM2.5 was increased by 5-8 times relative to the monthly average concentration. During the intense sandstorm, the concentration of particulate matter was in a clear upward trend, and the increase of PM10 concentration was more obvious than that of PM2.5, which indicated that the sandstorm carried a large amount of coarse particle pollutants. On the contrary, during the occurrence of sandstorm, the average daily concentrations of SO2, CO and NO2 were in a decrease trend, which revealed that the sandstorm had a certain effect of diffusing O3. In addition, the locations of the regions with low visibility, high PM10 concentration and 3 hour positive pressure were basically accorded with and located in the rear of ground cold front, which could provide a synoptic basis for predicting and preventing sandstorm and its pollution. References | Related Articles | Metrics

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Multiscale Meteorological Characteristics during a Sandstorm in Minqin WEI Qian, LONG Xiao, TIAN Chang, ZHAO Jian-hua 2018, 35 (6):  1352-1362.  doi: 10.13866/j.azr.2018.06.12 Abstract ( 4 )   PDF (6493KB) ( 0 )   The multiscale meteorological characteristics during a strong sandstorm in Minqin on 27 March,2007 were analyzed using the data from Minqin Meteorological Station. The results were as follows: ① It was obvious that the development of meteorological elements was characterized by the multiscale variations in surface layer during the strong sandstorm. Specifically,there were two main periods of wind speed near the surface,and they were for 2.5 hours and 1 hour respectively,which was the same as the disturbed temperature at 20 m height.Different from wind speed and disturbed temperature,the period of PM10 concentration was for 1.5 hours,and there was a period of relative humidity longer than 3.5 hours; ② Wind speed signal on a scale about 1 hour occurred 3 hours earlier than that on a scale about 2.5 hours,which revealed that an adverse scale development of wind speed was apparent during the sandstorm.Compared with the signals of wind speed and PM10 concentration,the perturbed temperature signal on a scale about 1 hour emerged earlier and its intensity reduced when the sandstorm occurred; ③ It was found that the wind speed signal varied synchronously with the change of PM10 concentration signal during the sandstorm,however,its variation over the time was not synchronous with the disturbed temperature signal,which probably meant that the development of gravitational wave played a critical role in sand raising. References | Related Articles | Metrics

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Numerical Simulation of Climate Effect in East Asia by Plastic Film Mulching Farmland in Arid Area ZHAO Shu-man, ZUO Hong-chao, WEI Xiang-qian, YANG Bin, WU Li-yang, WANG Shi-xin 2018, 35 (6):  1363-1372.  doi: 10.13866/j.azr.2018.06.13 Abstract ( 8 )   PDF (6070KB) ( 0 )   As an effective way of farming,plastic film mulching on farmland is widely used in arid and semiarid areas in China. In order to study the climate effect of plastic film mulching on farmland in East Asia,in this research a model of heat-water transfer process on mulched farmland was developed based on carrying out the experimental observation and theoretical research and introducing the mulched farmland module into RegCM 4 and WRF model to carry out a climate simulation experiment in summer for 17 years.The outputted parameters,such as precipitation,soil moisture content,surface soil temperature,sensible heat flux and latent heat flux,were compared by RegCM 4 model with the experimental observation and theoretical value,and the parameters were verified by the outputted results of WRF model.The result showed that,after mulching plastic film,the regional climate model can be used to exactly describe the characteristics of farmland underlying surface.Further comparison revealed that the potential field and wind field could be changed by mulching plastic film through influencing heat and water transfer near surface,and the water vapor transmission was affected,resulting in a reduction of precipitation in northwestern and southwestern parts of China,but an increase of precipitation in southwest China and the Huai River Basin. References | Related Articles | Metrics

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Applicability of GPM and TRMM Remote Sensing Precipitation Products in the Central Tibet Plateau YU Kun-lun, ZHANG Yin-sheng, MA Ning, GUO Yan-hong 2018, 35 (6):  1373-1381.  doi: 10.13866/j.azr.2018.06.14 Abstract ( 6 )   PDF (2319KB) ( 0 )   In this paper, the uncertainties of satellite precipitation products, both of Global Precipitation Measurement (GPM) and widely used precipitation product—Tropical Rainfall Measuring Mission (TRMM), were evaluated based on the data from five meteorological stations in the Silin Co Basin in the Tibetan Plateau during the period from April 2014 to March 2015. The accuracies of GPM and TRMM were studied using the correlation evaluation index (Person Correlation Coefficient R), Error statistical evaluation index (including the root mean square error RMSE and percent bias PB) and classification statistical evaluation index (BIAS, POD, FAR and HKS score). The results showed that: ① The accuracy of GPM was higher than that of TRMM at both daily and annual timescales, and the precipitation was significantly overestimated if the TRMM products were used; ② Although GPM performed better than TRMM in detecting weak precipitation events, there were some big flaws of both products in detecting the heavy precipitation events; ③ The accuracy of GPM was obviously increased with the increase of timescale. References | Related Articles | Metrics

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Spatiotemporal Variation of Extreme Climatic Events in the Hulunbuir Grasslands during the Period of 1960-2017 CUI Feng-qi, TANG Hai-ping, ZHANG Qin, DAI Lu-wei 2018, 35 (6):  1382-1391.  doi: 10.13866/j.azr.2018.06.15 Abstract ( 10 )   PDF (4455KB) ( 0 )   Thirteen extreme climatic indices related with regional meteorological disasters and vegetation growth were calculated based on the daily meteorological data from 6 meteorological stations in the Hulunbuir Grasslands and its surrounding area during the period of 1960-2017. The linear trend method, Mann-Kendall test, Sen’s slope estimator and wavelet analysis were used. The results showed that the summer days (SU25), warm nights (TN90P), warm days (TX90P) and continuous warm days (CWD) used to characterize the extreme high temperature increased significantly (P<0.01) with the rates of 3.53 d·(10a)-1, 4.09 d·(10a)-1, 3.1 d·(10a)-1 and 2.67 d·(10a)-1 respectively. The exponential frost days (FD0) and cold nights (TN10P) used to characterize the extreme cold events decreased significantly with the rates of 3.22 d·(10a)-1 and 2.9 d·(10a)-1 respectively (P<0.05). The abrupt change of extreme temperature began from the 1990s. The region with the highest warming rate was located in the northeastern part of the study area. The significant period of extreme high temperature index was concentrated on the scale of 2-9 years. The maximum 5 day precipitation(RX5D)and consecutive wet index (CWD) in the study area were in a significantly decrease trend (P<0.01) with rates of 5 mm·(10a)-1 and 0.2 d·(10a)-1 respectively. The consecutive dry index (CDD) was in a slight increase, and the annual wet day precipitation (PRCPTOT) and precipitation intensity were in a slight decrease trend. The indices used to characterize the extreme precipitation events (common daily intensity index, wet day precipitation , consecutive dry index and maximum 5 day precipitation) were delimited along the central axis of the study area in a north-south direction. The drying index in the eastern region was in a decrease trend. Annual precipitation increased significantly. In the western region, the consecutive dryness index (CDD) increased, and the consecutive wetness index (CWD) decreased significantly. References | Related Articles | Metrics

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Effects of Different Climate States on Climate Change in the Tianshan Mountains and Neighbouring Areas ZHOU Ling, SUN Hui-lan, YANG Yu-hui, MA Qian, WU Shan-shan, ZHOU Yong-chao 2018, 35 (6):  1392-1401.  doi: 10.13866/j.azr.2018.06.16 Abstract ( 6 )   PDF (6578KB) ( 0 )   In this paper, the effects of different climatic states on climate change in the Tianshan Mountains were discussed based on the data of monthly temperature and precipitation from 26 meteorological stations during the period from 1961 to 2015. The purposes of this study were to provide more scientific and objective bases for monitoring, assessing and studying climate change in the study area. Research shows are as follows: ① The east Tianshan Mountains was a sensitive region to the temperature change under different climatic conditions, and the northern slope of the mountains was a sensitive region to annual precipitation change. Based on referring the change of Ⅳ state during the period of 1961-2015, the analyzed results of temperature elements and precipitation elements under State Ⅰ (1961-1990) and State Ⅱ (1971-2000) were higher, but those under State Ⅲ (1981-2010) were lower; ② By taking the mutation time of Ⅳ state as the criterion, there was holistically no mutation of temperature under State Ⅰ, but the mutation of temperature under State Ⅱ became earlier and that under State Ⅲ became later; ③ The grades of temperature and precipitation under State Ⅰ and State Ⅱ were lower, but those under State Ⅲ were higher. There were no the effects of different climatic states on the precipitation anomaly, and the effects of State Ⅲ on the temperature anomaly were the lowest; ④ Both the positive change and negative change occurred when the different climatic states were used to analyze the same elements in the Tianshan Mountains. Moreover, it is necessary to use multiple elements in making an objective evaluation on the analyzed results of climate change using the climatic criterion. References | Related Articles | Metrics

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GIS-based Estimation of Meteorological Disaster Risk During Tibetan Sheep Growth HAN Bing-hong, ZHOU Bing-rong, ZHAO Heng-he, SHI Ming-ming, SUN Ying, NIU De-cao, FU Hua 2018, 35 (6):  1402-1409.  doi: 10.13866/j.azr.2018.06.17 Abstract ( 8 )   PDF (2911KB) ( 0 )   Tibetan sheep in alpine fragile ecological environment was researched using the daily meteorological data during the period of 1961-2017,and the vulnerability of the sheep,environmental sensitivity and social and economic conditions were analyzed.The theory model of disaster,meteorological disaster risk estimation and ArcGIS spatial analysis were applied to lucubrate and estimate the sheep growth in different periods.The results showed that the risk in the alpine zone was higher in lambing and shearing periods but lower in the hills and on the gentle slope.In copulation and grass harvest periods,the risk was higher in the hills and valleys and on the gentle slope but lower in the nalpine zone.Thus it can be seen that terrain is a dominant factor affecting Tibetan sheep growth in the alpine zone. References | Related Articles | Metrics

Biological Resources

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Variation of NDVI and Its Response to Climate Change in Hoh Xil during the Period of 1982-2015 CHEN Deng-kui, MA Chao, WANG Xia-bing, LIU Chang 2018, 35 (6):  1410-1417.  doi: 10.13866/j.azr.2018.06.18 Abstract ( 865 )   PDF (2127KB) ( 886 )   In this study,the latest data of GIMMS NDVI 3g plus,MVC,trend analysis,coefficient of variation and partial correlation analysis were used to study the spatial and temporal distribution and change trend of NDVI in the Hoh Xil Natural and Cultural Heritage Reserve in Qinghai Province during the period of 1982-2015 and to analyze the driving factors.The results showed that: ① The NDVI in the study area increased gradually from northwest to southeast due to the change of water and heat conditions caused by altitude; ② During the period of 1982-2015,the NDVI in the study area was in an obvious increase trend,the increase rate of NDVI in the core was 0.69%·(10a)-1,and it was 0.41%·(10a)-1 higher than that in the buffer area; ③ The area of the regions with NDVI improvement in the study area was much larger than that with NDVI degeneration,and the NDVI was holistically in a slow increase trend.The areas of the regions with NDVI improvement and NDVI degeneration in the core accounted for 47.92% and 3.00% respectively,65.70% area in the buffer area was basically maintained; ④ The area of the regions with relatively low and moderate NDVI fluctuation in the 34 years accounted for 75.54% of the total,and these regions were mainly distributed in the central and southern parts of the core and most areas of the buffer zone; ⑤ The results of correlation and partial correlation analysis showed that the NDVI in the study area was affected by temperature and precipitation,especially by temperature. References | Related Articles | Metrics

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Spatiotemporal Variation of Vegetation Phenology and Its Driving Factors in the Bayanbuluk Region GAO Qing, Alishir Kurban, XIAO Hao 2018, 35 (6):  1418-1426.  doi: 10.13866/j.azr.2018.06.19 Abstract ( 5 )   PDF (1673KB) ( 0 )   Vegetation phenology is the most significant and intuitive indicator of climate change, and it is of great significance for understanding the interaction between climate change and vegetation phenology. The response and feedback of different ecosystems to climate change are different. It is of great significance for understanding the mechanism of phenological change to explore the relationship between spatiotemporal variation of vegetation phenology and its driving factors in various ecosystems under climate change. In this study, the Bayinbuluke with a variety of ecosystems was selected as the study area. The MODIS NDVI time-series data during the period of 1989-2011 were used to get the spatial distribution and spatiotemporal variation of vegetation phenology, and to analyze its relationship with elevation and climate factors. The results showed that: ① The beginning time of vegetation growth season was mainly from early April to mid-May, and the ending time was mainly from mid-September to mid-October; ② The beginning time of vegetation growth season in most regions of the study area became earlier during the period of 2001-2017, and that of the grassland, meadow and swamp became significantly earlier except for the alpine vegetation. The ending time of vegetation growth season became earlier in the north of the study area but was delayed in the south, and that of the alpine vegetation and grassland became significantly earlier; ③ On the whole, the beginning time of vegetation growth season was delayed but the ending time became earlier with the increase of elevation, and phenological difference among different ecosystems was decreased with the increase of elevation; ④ There was a negative correlation between the beginning time of vegetation growth season and the spring temperature. The beginning time of growth season of alpine vegetation was significantly affected by temperature in May, that of grassland and swamp by temperature in April, and that of meadow by temperature in April and May. References | Related Articles | Metrics

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Effects of Environmental Factors and Interspecific Competition in Community Biodiversity Pattern ZHU Ling, JIN Yi-lan, CONG Ri-hui, LIU Qing-fu, DING Yong, ZHANG Qing 2018, 35 (6):  1427-1435.  doi: 10.13866/j.azr.2018.06.20 Abstract ( 7 )   PDF (1303KB) ( 0 )   This study was conducted in hillside in a typical grassland enclosed for many years in Inner Mongolia,and six transects with 96 sample plots in total were evenly designed along the slope.The purposes of the study were to explore the effects of slope position on species diversity and functional diversity of a typical grassland community,and to discuss the effects of environmental factors and interspecific competition in two different dimensions of diversity.The results showed that: ① The trend of species diversity and functional diversity of the community was consistent with the change of slope position.With the increase of slope position,the species richness and functional richness of the community decreased monotonically; while the species evenness,species dominance,functional evenness and functional dispersion increased at first and then decreased; ② The total phosphorus content on the whole slope was the main factor affecting the species richness of the community and correlated with the functional richness significantly.Interspecific competition was the key factor affecting the species evenness,species dominance,functional dispersion and functional evenness and correlated with the functional evenness significantly; ③ The species diversity and functional diversity of the community were mainly affected by the interspecific competition and environmental factors in the uphill position,but mainly affected by interspecific competition in the downhill position.Therefore,the joint effects of environmental factors and biological factors should be taken into account in exploring the change of community biodiversity pattern. References | Related Articles | Metrics

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Allelopathic Effect of Foliage Water Extract of Artemisia halodendron on Seed Germination of Four Herbaceous Species in Sandy Land DING Jie-ping, YAN Zhi-qiang, CHEN Yin-ping, LI Yu-qiang, LUO Yong-qing 2018, 35 (6):  1436-1443.  doi: 10.13866/j.azr.2018.06.21 Abstract ( 4 )   PDF (2131KB) ( 0 )   Artemisia halodendron is one of the dominant species in vegetation succession for sand land restoration.At the initial stage of vegetation regeneration over sand land,A.halodendron was one of the dominant specie over semi-fixed dune.Thereafter it is replaced by other annual or perennial species,such as Lespedeza bicolor,Corispermum macrocarpum and Agropyron cristatum with the development of sand land recovery.However,the mechanism of its succession is still unclear.In this study,we focused on the allelopathic effect of leaf water extract with different concentrations (0,10,20,40,60,80 and 100 g·L-1) from A.halodendron on seed germination of one symbiosis specie Seteria virids and three competitive species in terms of L.bicolor,C.macrocarpum and A.cristatum.The results showed that the leaf water extract of A.halodendron affected seed germination of S.virids slightly,and which was promoted under low concentration of the foliage water extract of A.halodendron.However,the seed germination was significantly inhibited by the foliage water extract of A.halodendron,and this allelopathic inhabitation was increased with the increase of the concentration.In conclusion,A.halodendron showed a strong allelopathic effect to other species in vegetation regeneration in the process of sand land restoration.Allelopathic effect was induced by the matters released from the fallen leaves,which may be one of the vital strategies to keep competitiveness. References | Related Articles | Metrics

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Effects of Salt and Water Stress on Seed Germination of Gymnocarpos przewalskii WEI Zhen-yan, HUANG Hai-xia, OUYANG Er-qian, YANG Qi-qi, LIAN Zhuan-hong 2018, 35 (6):  1444-1449.  doi: 10.13866/j.azr.2018.06.22 Abstract ( 2 )   PDF (1462KB) ( 0 )   In this study,the effects of simulated water (PEG-6000) and salt (NaCl) stresses on seed germination of Gymnocarpos przewalskii were analyzed so as to determine its drought and salt tolerance by designing the osmotic potentials of -0.3,-0.5,-0.7,-0.9 and -1.2 MPa and distilled water as control (0 MPa).The result showed that the seed germination of G.przewalskii was inhibited significantly by the two stresses.PEG stress reduced significantly the seed germination index,vigor index and radicle length.When the osmotic potential was ≤-0.7 MPa,the germination rate was significantly decreased.Germination index and radicle length were decreased significantly under NaCl stress.When the osmotic potential was ≤-0.9 MPa,the germination rate was significantly reduced.Germination index,vigor index and radicle length were sensitive to salt and water stresses and could be used as the main indexes to evaluate the drought and salt tolerance of G.przewalskii seeds.Under iso-osmotic condition,when the osmotic potentials were -0.7 MPa and -0.9 MPa,the germination rate,vigor index and hypocotyl length of PEG stress were significantly lower than those of NaCl stress; when the osmotic potential was ≤-0.7 MPa,the germination potential and germination index under PEG treatment were significantly lower than those under NaCl treatment,which indicated that the main factors affecting seed germination was osmotic stress rather than ionic toxicity.The critical and limit values of seed germination were -0.8 MPa and -1.1 MPa respectively under PEG stress,and they were -1.5 MPa and -2.2 MPa under NaCl stress.Which indicated that the salt tolerance of seed germination of G.przewalskii was higher than drought tolerance. References | Related Articles | Metrics

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Effects of Climate Change and Human Activities on the Distribution Pattern of Calligonum mongolicum Turcz. Sayit Hamit, Nurbay Abdushalih, LI Xue-ping, SHAO Hua, Arman Jiesisi, Ateng Guli 2018, 35 (6):  1450-1458.  doi: 10.13866/j.azr.2018.06.23 Abstract ( 5 )   PDF (2156KB) ( 0 )   Calligonum mongolicum Turcz. is an important species of vegetation in desert, and is also a preferred species for artificial sand-fixation and afforestation. This study was based on the geographical distribution of 119 geographical distribution data of C.mongolicum and 24 environmental variables. The effects of climate change and human activities on the distribution pattern of C.mongolicum were elucidated using the CMIP5 reduction global model data. The MaxEnt model and ArcGIS spatial analysis means were used to develop the models of predicting suitable habitats of C.mongolicum under different climatic conditions and human activities so as to quantitatively demonstrate the different climate change scenarios (RCP2.6, RCP 4.5, RCP 8.5) and the change of distribution pattern of C.mongolicum in China under climate change. The results showed that the prediction accuracy of the model was relatively high (the AUC values of the training data set and the test data set were 0.958 and 0.951 respectively). The main climatic factors affecting the distribution of C.mongolicum were precipitation, topographical factors and elevation, and the disturbance of human activities made the suitable proportion of C.mongolicum decrease from 13.04% to 9.57%. The breeding habitat of C.mongolicum was negatively correlated with human activities. Under current climatic conditions, the proportions of total suitable area of C.mongolicum was 13.04%; in the three scenarios of RCP2.6, RCP4.5 and RCP8.5, the predicted proportions of total adaptive area would be 13.36%, 13.18% and 14.78% up to the 2050s, and they would be 13.39%, 12.76% and 12.71% up to the 2070s. The change of scope and area of adaptation is different. References | Related Articles | Metrics

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Effects of Self-healing of Caragana microphylla on Root Soil Reinforcement in Arid Diggings WANG Bo, LIU Jing, WANG Chen-jia, ZHANG Xin, LI Qiang, LIU Jia-wei, ZHANG Qiang 2018, 35 (6):  1459-1467.  doi: 10.13866/j.azr.2018.06.24 Abstract ( 4 )   PDF (1413KB) ( 0 )   In this study, the HG100 digital push & pull tester and self-developed experimental installation were used to investigate the anti-fracture mechanical properties of tap roots (diameter was 1-4 mm) and lateral roots of Caragana microphylla before and after occurring the fracture force injury. The purposes of the study were to clarify the effects of fracture force injury on mechanical properties and self-healing mechanism of plant roots after soil erosion occurred in the Shendong diggings. The results indicated that: ① There was a positive power function correlation between the root ultimate anti-fracture force and root diameter of C.microphylla in early growth season, but a negative one between the anti-fracture strength and root diameter. Moreover, the ultimate anti-fracture force and strength of tap roots were higher than that of lateral roots. ② The fracture force injury restricted significantly the normal growth of roots, and the activity, growth and survival rate of C.microphylla roots after self-healing were all lower than those of contrast. Root diameter and root type were the important factors affecting evidently such restriction, the activity and survival rate of lateral roots were decreased more significantly than those of tap roots after injured; ③ The ultimate anti-fracture force and strength of C.microphylla roots were increased to some extent after self-healing compared with those in early growth season, but such increase was restricted by the external injury, and the growth rate was significantly lower than that of control. The self-healing rates of ultimate anti-fracture force and strength after three months were 48.91% and 57.59% respectively. In conclusion, the root system could not completely lose its soil reinforcement capability after injured, the original function could be restored gradually through self-healing capability. The self-healing rates of tap roots and lateral roots were 60.55% and 36.34% respectively, which showed that the self-healing capability of tap roots was obviously higher than that of lateral roots. References | Related Articles | Metrics

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Spatiotemporal Evolution of Vegetation Cover and Surface Humidity Since Implementing the Grain for Green Project in the Loess Plateau ZHANG Chong, WANG Jing, LEI Tian-wang, MA Ling, SONG Dian-xing 2018, 35 (6):  1468-1476.  doi: 10.13866/j.azr.2018.06.25 Abstract ( 4 )   PDF (3027KB) ( 0 )   Based on the MODIS data and Landsat data during the period from 2000 to 2014, the temperature vegetation drought index was used to reflect the surface humidity, and the temporal and spatial changes of surface humidity and vegetation cover on the Loess Plateau since implementing the Grain for Green Project were analyzed. The findings suggested as follows: ① The growth rate of normalized vegetation index in the Loess Plateau during the period from 2001 to 2014 was 6.3%·(10a)-1, the temperature vegetation drought index was decreased by -4.5%·(10a)-1, the vegetation cover and surface humidity were increased, the vegetation coverage was high in the southeast but low in the northwest, and it could be generally seen that there was a positive correlation between the surface humidity and the vegetation coverage; ② According to the change trend of TVDI and NDVI, the vegetation cover and surface humidity were in an increase trend in the Loess Plateau. The spatial change of vegetation cover was in accordance with the variation of surface humidity perfectly, but there was a regional difference; ③ The correlative coefficient indicated that there was a positive correlation between the vegetation cover and the surface humidity in the Loess Plateau. From the perspective of the change trend, the changes of vegetation cover and surface humidity in the northeast-southwest zone of the Loess Plateau in 14 years were beneficial to the improvement of ecological environment. Intensive human activities in the plain are very unfavorable to the improvement of ecological environment. It is worth to pay attention to the key areas where the Grain for Green Project is implemented because they are critical for monitoring and managing the ecological environment change in the future so as to avoid degenerating again. References | Related Articles | Metrics

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Effect of Grain for Green Project on Vegetation Regeneration in Shaanxi Province:Based on PCSE Panel Data Model CHENG Pei-kun, HU Shou-geng, SUN Tao, CHEN Hai-bin 2018, 35 (6):  1477-1486.  doi: 10.13866/j.azr.2018.06.26 Abstract ( 7 )   PDF (3515KB) ( 0 )   In this paper,the temporal and spatial variations of vegetation cover in Shaanxi Province were analyzed.The purposes of this study were to explore the driving effect of the Grain for Green Project on vegetation regeneration,and the relative contributions of some natural and socio-economic factors (such as the Grain for Green Project and rainfall level) to vegetation cover change were estimated based on the SPOTVEG NDVI data during the period from 1998 to 2013 by using the pixel dichotomy method and the Panel Corrected Standard Errors (PCSE).The result showed that the vegetation coverage in Shaanxi Province was holistically improved,the annual average NDVI value was increased by 0.98% from 1998 to 2013,and the effect of vegetation regeneration was obvious by implementing the Grain for Green Project from 1998 to 2009.The spatial difference of vegetation regeneration effect in the province was significant.During the 16 years,the NDVI in the province increased with different rates,it was increased by 0.1 in 40.61% area,by 0.2 in 29.05% area,and by 0.25 in 23.69% area.In which the most evident effect of the project on vegetation regeneration occurred in Yan’an City located in north Shaanxi Province,where the NDVI was increased by 1.12%.The NDVI was increased by 1.97% if the Grain for Green Project was implemented in 1% area of the total,which was equivalent to increasing 4.29% precipitation.The results of this study are of great significance for reconstructing the ecological environment in the study area. References | Related Articles | Metrics

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Change Trend of Residual Film in Soil in Cotton Field under the Long-term Mulched Drip Irrigation HE Huai-jie, WANG Zhen-hua, ZHENG Xu-rong, ZHANG Jin-zhu, LI Wen-hao 2018, 35 (6):  1487-1495.  doi: 10.13866/j.azr.2018.06.27 Abstract ( 8 )   PDF (1762KB) ( 0 )   In order to explore the pollution and distribution of residual mulching plastic film in soil in cotton field in recent 30 years, the sample plots in 121st State Farm of Xinjiang Corps of Production and Construction were selected as the experimental areas, where the mulching film was used for 5, 9, 11, 13, 15 and 19 years respectively. The Matlab program was used to develop the BP neural network model for hierarchical prediction and overall prediction of sample data. The results showed that the residual film area and quality data predicted with the model could be used to perfectly reflect the distribution of residual film in soil in cotton field in recent 30 years. The residual film in topsoil was broken year by year with the time increase of mulching plastic film and moved down to deep soil (30-40 cm). The predicted result revealed that the residual film density in cotton field would reach 419.19 kg·hm-2 after mulching plastic film was used for 30 years, which would be nearly 6 times of the national standard limit (75.0 kg·hm-2). In order to solve this problem, it is suggested to use the plastic film thicker than 0.010 mm, increase the recovery of mulching plastic film, and ensure the sustainable development of cotton field. References | Related Articles | Metrics

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Effect of Barchan Dune on Surface Wind Erosion over Lacustrine Plain CAI Dong-xu, LI Sheng-yu, LEI Jia-qiang, WANG Hai-feng, MENG Xiao-yu 2018, 35 (6):  1496-1504.  doi: 10.13866/j.azr.2018.06.28 Abstract ( 1672 )   PDF (2086KB) ( 856 )   Barchan dune is an important type of aeolian landform and forms during the process of desertification. In the previous researches, more researchers focused mainly on the surface dynamic process of barchan dune but less on the influence of barchan dune on surface wind erosion during desertification process. In this paper, the plugging-brazing method was used to measure the distribution pattern of wind erosion/deposition on the surface around barchan dunes at the Taitema playa. The wind tunnel was used to simulate the distribution pattern of airflow over the typical barchan dune. The mechanism of barchan dune affecting surface wind erosion around dune was analyzed. The results showed that the airflow structure changed with the varying geometry shapes of barchan dunes, and it affected significantly the intensity of wind erosion/deposition over the surface. Although the wind erosion depth and sedimentary thickness were slightly greater than those on flat sand, the average volume of net wind erosion per unit area was close to an equilibrium in the frontal region of windward slope and on both sides of dunes. Deposition was dominant in the frontal region on leeward slope of barchan dune, but wind erosion was dominant on the surface of flank wake zone of leeward slope. The average volume of net wind erosion per unit area was slightly increased with the increase of dune size. In a word, the barchan dunes affect the intensity of surface wind erosion and deposition during the process of desertification in playa. References | Related Articles | Metrics

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Structure of Drifting Sand Flow over the Surface of Blowouts in the Hulun Buir Sandy Grasslands ZHANG Xi-wei, WANG Ji, HAI Chun-xing, DING Yan-long, BAO Cheng 2018, 35 (6):  1505-1511.  doi: 10.13866/j.azr.2018.06.29 Abstract ( 2 )   PDF (2207KB) ( 0 )   The blowouts at different development stages in the northern sandy zone of the Hulunbuir sandy grasslands were selected to analyze and compare the structure of drifting sand flow based on the simultaneous observation of wind-sand flux over blowout surface (0-200 cm). The purpose of the study was to provide a theoretical basis for wind erosion control in sandy grasslands. The results showed that the wind profiles were in a logarithmic distribution in the sand patches at their different development stages, while the un-eroded grasslands and the blowouts at their extinction stage were in an “S-shaped” distribution because the air flow was disturbed by the underlying surface. The optimal fitting model for sand flux and height over blowout at each development stage was a negative exponential model, and the difference of sand flux in blowout at different development stages was obvious. More than 95% sand flux was distributed within a height of 0-30 cm from the land surface, and 63.97%-90.96% sand flux was distributed in 10 cm height. The sand saltation height was positively correlated with wind speed and in an order of active development>reactivation stage>sand patch>fixed stage>extinction stage>un-eroded grassland. The analyzed results of sand flux coefficient revealed that the high value of sand flux moved upwards over sand patch at the active development and reactivation stages, and the wind-blown sand flux concentrated near ground because of the high vegetation coverage. References | Related Articles | Metrics

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CO2 Carbon Flux over Moraine Area of the Koxkar Glacier in the Tianshan Mountains WANG Jian, DING Yong-jian, XU Min, XU Jun-li 2018, 35 (6):  1512-1520.  doi: 10.13866/j.azr.2018.06.30 Abstract ( 670 )   PDF (1891KB) ( 575 )   At some flux sites, the alpine zone surrounding the measuring tower is affected by complex topography and strong wind, which results in the distortion of atmospheric CO2 flux. The goal of this study was to carry out a numerical experiment with the eddy covariance system in moraine area of the Koxkar Glacier in the Tianshan Mountains, and to evaluate the integral of footprint function over the considered domain and distance of the corresponding farthest point from the sensor with the ART (Agroscope Reckenholz Tanikon) Footprint Tool base on the Kormann Meixner method. Results are as follows: ① The prevailing wind direction in snow accumulation period was NW, and its frequency accounted for 53.31%. NW wind evolved gradually into NNW one in snow melting season and early ice-glacial ablation season; ② Atmospheric CO2 sank during the majorly typical period and even snow accumulation period, because soluble substances reacted chemically under snow-ice melting; ③ Temporally, the proportion of more than 80% 0.5 h CO2 flux data of footprint function in each period was in an order of >snow accumulation period (95.96%)>snow melting period (93.75%)>intense glacial ablation season (86.30%)>early glacial ablation season (82.35%). The footprint distance to the farthest point was almost in reverse order, which meant that the major areas of CO2 flux contribution were relatively concentrated, and the effect of CO2 flux change at the glacial terminal and on the ridges could be ignored; ④ Under the stable atmosphere in the daytime, the CO2 flux (78.55±2.08)% was slightly higher than that under the unstable atmosphere (77.72±1.41)% at night, but they were significantly lower than the interpretated ones. References | Related Articles | Metrics