Table of Content

15 May 2018, Volume 35 Issue 3 Previous Issue    Next Issue

Land and Water Resources

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Characteristics of Soil Salinity in Arid Oasis WANG Qiao-huan, LU Yu-dong, SAI Jia-mei, LI Huan-huan 2018, 35 (3):  503-509.  doi: 10.13866/j.azr.2018.03.01 Abstract ( 734 )   PDF (1408KB) ( 673 )   The study area is located in the Yaoba Oasis irrigated area in the Alxa League of Inner Mongolia.Based on the field investigation,in this paper the distribution of total salt and salt ions in topsoil samples collected from the Yaoba Oasis was analyzed using the descriptive statistical method,correlation analysis and principal component analysis (PCA).According to the descriptive statistical analysis,the results showed that the topsoil in the oasis is alkaline chlorine-sulfate salinized soil.The cations in topsoil were dominated by Ca2+ and K++Na+,and HCO3- was dominant in anions.The total salt content in topsoil was high in the southwest but low in the northeast.Total soil salt content varied obviously from the east to the west but slightly from the south to the north.In topsoil,the variability of salt ions of HCO3-,K++ Na+,SO42- and Cl- was strong,that of Ca2+,Mg2+ and HCO3- was moderate,and that of pH value was slight.The correlation analysis revealed that there were the extremely significant positive correlations between total soil salt content and SO42-,Ca2+,K++Na+,Cl- and Mg2+,and the correlation coefficient between total soil salt content and SO42- was the highest (0.958).There were the extremely significant negative correlations between total soil salt content and Mg2+,Ca2+,Cl- and SO42-,and all the correlation coefficients were lower than 0.6.According to the PCA,there were two principal component factors,and they could be used to reflect the salt content in topsoil in the study area.One could be used to reflect the soil salt component,and another could be used to reflect the soil alkalinity,so it was concluded that SO42-,K++Na+,Ca2+ and Cl- could be used to characterize soil salinization.Moreover,the equations of comprehensive scores of the principal components were developed.According to calculated results of comprehensive scores of 42 soil samples,the values ranged from 3.6 to 10.7,the average value was 5,and the standard deviation was 1.5,so the variability was moderate.The study results could provide the theory and practical basis for preventing and controlling soil salinization and for safe development of agriculture and animal husbandry in the study area. References | Related Articles | Metrics

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Effects of NaCl on the Growth and Mineral Nutrient Content of Plants Grown from Dimorphic Seeds of Suaeda aralocaspica WANG Lei, JIANG Li, TIAN Chang-yan 2018, 35 (3):  510-514.  doi: 10.13866/j.azr.2018.03.02 Abstract ( 41 )   PDF (756KB) ( 4 )   Suaeda aralocaspica,an annual halophyte growing in the deserts in Central Asia,produces two distinct types of seeds that differ in shape,color,dormancy and germination. Brown and black seeds of S.aralocaspica have different salt tolerance during germination.However,there was no significant difference in salt tolerance of S.aralocaspica plants grown from dimorphic seeds at late growth stage.The possibility that plants grown from dimorphic seeds at middle growth stage may differ in salt tolerance was not investigated previously.Experiments were designed to investigate the growth and mineral nutrient concentrations of plants grown from dimorphic seeds of S.aralocaspica under different salinity levels.There was no significant difference between plants grown from dimorphic seeds with respect to growth and most physiological parameters.Low to medium salinity promotes the plant growth,but high salinity inhibits the plant growth.The biomass of S.aralocaspica plants growing under medium salinity was the highest.Concentrations of Na+ and Cl- were increased with the increase of supplied salinity.This indicated that S.aralocaspica plants require a certain amount of salinity to maintain osmotic homeostasis.In conclusion,the salt tolerance of the plants grown from dimorphic seeds of S.aralocaspica at middle growth stage was similar.The carry-over of differential salt tolerance in plants grown from dimorphic seeds may display at the early stage of plant growth. References | Related Articles | Metrics

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Response of Soil Microbial Biomass Carbon and Nitrogen Deposition to Precipitation and Temperature in the Gurbantunggut Desert WU Wen-chao, YUE Ping, CUI Xiao-qing, LI Kai-hui, LIU Xue-jun 2018, 35 (3):  515-523.  doi: 10.13866/j.azr.2018.03.03 Abstract ( 59 )   PDF (1454KB) ( 1 )   Soil microbial biomass plays a critical role in soil nutrient cycling and is sensitive to atmospheric nitrogen deposition,rainfall change pattern and global warming. However,the effects on soil microbial biomass,especially seasonal one,are still unclear.Therefore,a field multiple-factor experiment including precipitation increase,nitrogen addition and temperature increase was conducted in the Gurbantunggut Desert in September 2014 so as to understand the effects of atmospheric nitrogen deposition,precipitation and global warming on soil microbial biomass carbon(MBC)and nitrogen(MBN)in different seasons in temperate desert ecosystem.It was found that there were no seasonal differences in the responses of soil MBC and MBN and the ratio of MBC to MBN and simulated rainfall.The soil MBC and MBN and the ratio of MBC to MBN were positively correlated with nitrogen addition,and the high nitrogen in autumn 2015 affected significantly the MBC and MBN and the ratio of MBC to MBN.The temperature increase in autumn 2015 and spring 2016 decreased the soil MBC and MBN and the ratio of MBC to MBN,but increased significantly these in summer 2016.The precipitation and nitrogen increase affected interactively the seasonal soil MBC and MBN and the ratio of MBC to MBN,but the effects of interaction of nitrogen,precipitation and temperature increase on the seasonal soil MBC and MBN and the ratio of MBC to MBN were not significant.Owing to the ratio of MBC to MBN ranged from 1.52 to 4.34,our results suggested that bacteria were dominant in soil microbial community in the Gurbantunggut Desert. References | Related Articles | Metrics

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Spatial Variation of Soil Organic Carbon Content and Its Driving Factors along South-North Transect in the Loess Plateau of China REN Guang-qi, JIA Xiao-xu, JIA Yu-hua, GUO Cheng-jiu 2018, 35 (3):  524-531.  doi: 10.13866/j.azr.2018.03.04 Abstract ( 803 )   PDF (1279KB) ( 605 )   The China’s Loess Plateau is characterized by severe water shortage,thick loess deposits and intensive soil erosion,and it is a typical ecological fragile region in China and even around the world.Serious soil erosion and long-term irrational land reclamation in this region leads to a decline of soil organic carbon content(SOC).As an important component in the terrestrial ecosystem,the SOC which is closely related to soil physical,chemical and biological properties is a key factor affecting soil fertility and productivity of ecosystem.Slight fluctuation of soil organic carbon pool,which is caused by the changes of land use,land management measures or soil erosion rate,affects strongly the carbon dioxide in atmosphere and thus the global climate change.The spatial distribution of SOC has generally a high heterogeneity due to the influence of climate(i.e.temperature and precipitation),soil texture,soil type,vegetation type,terrain conditions(such as elevation,slope aspect and slope gradient)and land use type.However,the SOC was focused on mainly on the small spatial scales (generally<2 km2)in previous studies,which is insufficient for understanding the spatial characteristics of SOC on regional and/or global scale.Besides,the available researches overlooked the amount and spatial pattern of SOC in deeper soil layers (deeper than 1 m),which failed to provide a reliable evidence for precise regional soil carbon stock evaluation.In this study,an 860-km south-north transect was designed,and the values of SOC at 500 cm depth were measured at an interval of 10 km(n=86) along the transect.Thus,the objectives of the study were to investigate the spatial variation of SOC on regional scale and to derive the primary factors dominating the spatial distribution of SOC in different soil layers by using the classical statistics and geostatistics.The results showed that the mean SOC of the 0-500 cm soil profile decreased generally from the south to the north of the plateau along the horizontal direction.Along the vertical direction,SOC decreased gradually with the increase of soil depth above 100 cm soil layer,while it tended to be stable in the 100-500 cm layer.Under different land use types,SOC was generally in an order of cropland(5.79 g·kg-1)>forestland (3.34 g·kg-1)>grassland(2.20 g·kg-1).A moderate variation of SOC occurred in various soil layers along a 0-500 cm profile,and the best fitting semivariogram models for SOC in the 0-150 cm and 150-500 cm soil layers were Gaussian and Exponential.The controlling factors of SOC were different from different soil layers:SOC in the top 40 cm soil layer was mainly influenced by mean annual precipitation and slope gradient,while that in the 40-500 cm soil layer was controlled by soil texture,mean annual precipitation and temperature.Results suggested that the regional distribution of SOC in shallow soil layers(<40 cm in depth) was determined by climate and topographic conditions,while that in deep soil layers (40-500 cm in depth)tended to be determined by soil texture and climate.The results could provide a scientific basis for ecological regeneration and regional soil carbon stock evaluation. References | Related Articles | Metrics

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Estimation of Soil Moisture Content in North Tibet Based on Vegetation Spectra and FY-3A/VIRR L1B Data WANG Feng-jie, FENG Wen-lan, Zhaxiyangzong, NIU Xiao-jun, LIU Zhi-hong, WANG Yong-qian 2018, 35 (3):  532-539.  doi: 10.13866/j.azr.2018.03.05 Abstract ( 67 )   PDF (1249KB) ( 2 )   In order to dynamically monitor soil moisture content and drought in north Tibet,this study tried to build a model to estimate soil moisture content.The model was based on the measured data of soil moisture content and vegetation indexes sensitive to soil moisture content.Firstly,the sensitive bands of soil moisture content were screened out through correlation analysis between the hyper-spectral reflectance and the first-order differential reflectivity with soil moisture content.The sensitive spectral parameters of soil moisture content were identified through establishing vegetation indices,including the ratio vegetation index RVI (850,1 330),normalized difference water index NDWI (850,1 330),enhanced vegetation index EVI (450,620,850) and normalized difference vegetation index NDVI (620,850).Secondly,the estimation model was established based on the data of soil moisture content and the vegetation indices from the measured hyperspectral values.Thirdly,the FY-3A/VIRR L1B data were preprocessed,including the atmospheric correction and geometric correction,and then the vegetation indexes were calculated.Finally,the vegetation indices of FY-3A/VIRR data were replaced by the vegetation indices from the measured hyperspectral values in the estimation model.In order to find the best estimation model,the model accuracy was judged by the determination coefficient (R2) and the root mean square error (RMSE).The results showed that all the indexes could be used to reflect the soil moisture content.The correlation coefficients between the NDVI (620,850),EVI (450,620,850),NDWI (850,1 330),RVI (850,1 330) and the soil water content were 0.232,0.256,0.537 and 0.554 respectively.Then,the corresponding models of estimating soil moisture content were established based on these indexes.Among them the best estimated results were obtained using the quadratic model because of the higher R2 and lower RMSE.The vegetation indices of FY-3A/VIRR data were brought into the model of estimating soil moisture content,the accuracy of MNDVI and MEVI for estimating soil moisture content was similar.The r values were 0.50 and 0.51,and the RMSE ones were 0.13 and 0.11,respectively.The results showed that the model MNDVI and MEVI could be used to effectively estimate soil moisture content in north Tibet.This study could provide a new method for the field hyperspectral estimation of soil moisture content in north Tibet,may be feasible to carry out the remote sensing monitoring of soil moisture content,and could also be referred in the further improvement of the accuracy of quantitative remote sensing monitoring of soil moisture content in different areas. References | Related Articles | Metrics

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Two Kinds of Ecological Service Values of Soil and Water Conservation in the Ili River Valley GAO Ya-ming, SUN Hui-lan 2018, 35 (3):  540-548.  doi: 10.13866/j.azr.2018.03.06 Abstract ( 51 )   PDF (1720KB) ( 2 )   It is a challenging task to conserve soil and water at the ecological aspects in the Ili River Valley.The potential impact of soil erosion should be paid great attention to in both ecological governance and further development.Distribution of soil erosion should be grasped so as to further clarify the development direction.A unified standard for estimating the ecological service value is not formed yet.Different valuation methods may produce an enormous difference in the results.The lack of comparability between the different assessment results has seriously hampered the widespread application of ecological service value in solving the practical social problems.In this paper,the main sources of various satellite remote sensing data in the Ii Valley during the period from 2001 to 2013 were analyzed.Options for assessing the value of ecological services in this paper included two approaches,i.e.the “index construction” and “equivalence factor”.During the assessment process,a number of empirical models were used,and their corrections were made based on the actual data of the study area.On which the assessed results of ecological service value were obtained based on soil and water conservation in the Ili Valley.The commons and differences of the conclusions obtained by the two methods were discussed.The results of this study showed that,during the study period,the annual soil and water conservation in the natural ecology in the Ili Valley was 2.64×108 t.The value of soil-related ecological services assessed by the “Indicator Construction method” was 2.38×108 to 4.72×108 yuan.The value of soil-related ecological services assessed by the “Equivalent Factor method” was 182.99×108 to 201.81×108 yuan,of which the highest value occurred in Zhaosu County where the ecological conditions are fine,and the lowest one occurred in Yining City.The difference between the two methods in the calculation was nearly a hundredfold.The geometric mean method was used to balance the results of the extreme differences.Combining the two results,the final average soil-related ecological service value in the Ili Valley was 23.95×108 yuan.The results from the two methods were similar.Maximum and minimum values of ecosystem services occurred in 2007 and 2012 respectively.The highest (29.73×108 yuan) and the lowest (20.93×108 yuan) ecological service values occurred in 2007 and 2012 respectively.The average annual ecological service value was high in Zhaosu County and Turks County but low in Yining County and Yining City. References | Related Articles | Metrics

Climatic Environment

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Spatiotemporal Variation of Air Temperature in the Middle and Eastern Parts of the Qilian Mountains and the Nearby Regions during the Period of 1960-2014 FU Jian-xin, CAO Guang-chao, LI Ling-qin, CAO Sheng-kui, TANG Zhong-xia, JIANG Gang, YANG Xiao-min, YU Min, YUAN Jie, DIAO Er-long 2018, 35 (3):  549-561.  doi: 10.13866/j.azr.2018.03.07 Abstract ( 34 )   PDF (5788KB) ( 1 )   In this study,the linear trend,correlation analysis,polynomial trend,5 year moving average,R/S analysis,Mann-Kendall test,sliding t-test and ARCGIS method were used to make a detailed analysis on the temporal variation and spatial distribution of temperature in the Qilian Mountains based on the temperature data from 19 meteorological stations in the middle and eastern parts of the Qilian Mountains and the adjacent regions during the period from 1960 to 2014.The results revealed that the multi-annual mean,maximum and minimum temperatures fluctuated with increase rates of 0.33 ℃·(10a)-1,0.27 ℃·(10a)-1 and 0.41 ℃·(10a)-1 respectively,and the temperature mutation occurred in 1991,1995 and 1990 respectively.The seasonal temperature was in an increase trend,and its increase rate reached a peak value in winter,which was mainly caused by the emission of greenhouse gases and the increase of atmospheric aerosol content.Interdecadally,the most significant temperature increase occurred in the 1990s,and the temperature increase trend was slowed down during the period of 2000-2014 compared with that during the period of 1990-1999.Such trend,however,could not considered that the global warming was stagnated because the Hurst index of temperature was between 0.5 and 1,and temperature variation trend in the future would be similiar to that in the past.Holistically,the temperature was low in the southwest but high in the east and the north.Difference of the multi-annual mean temperature variation between the north and the south was significant,the multi-annual mean temperature increase in the north was more significant than that in the south,the maximum temperature increase in the south was more obvious than that in the north,and the minimum temperature increase was similiar in both the north and south. References | Related Articles | Metrics

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PM2.5 Concentration over Typical Urban Green Spaces in Baotou City and Its Peripheral Regions Tongliga, LI Xue-ming, ZHANG Jing, TIAN Shen-zhen, CONG Xue-ping 2018, 35 (3):  562-567.  doi: 10.13866/j.azr.2018.03.08 Abstract ( 49 )   PDF (2049KB) ( 2 )   PM2.5 pollution has gradually become as the primary air pollutants over urban and regional areas in China.Baotou City is an important industrial base in China,and its PM2.5 pollution is serious.Based on the combination of field measurement and remote sensing means,the values of PM2.5 concentration over the typical urban green spaces in Baotou City and the surrounding roads and districts were compared and analyzed using the measured PM2.5 concentration data and Landsat 8 OLI image data,and the correlation analysis between NDVI and PM2.5 concentration was carried out.The results showed that the values of PM2.5 concentration over the Labor Park,Sai han Tara Ecological Park and Teachers’ College Grove were higher than that over the surrounding roads and the districts,those over the Children’s Park,Qingshan Park and Bayi Park were slightly lower or similar to those over the peripheral regions,and there was a weak negative correlation between NDVI and PM2.5 concentration.On the whole,the urban green spaces play a certain role in reducing the PM2.5 concentration.The high values of PM2.5 concentration over the urban green spaces was mainly caused by the high humidity,high canopy closure,low wind speed and dust emission. References | Related Articles | Metrics

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Effects of Land Use/Cover Change on Regional Environment in the Hami Oasis DU Hao-yang, HU Qi, ZHANG Chi, QIU Yuan, SHAO Hua, PAN Tao, JIN Xiao-long, CHANG Hong 2018, 35 (3):  568-578.  doi: 10.13866/j.azr.2018.03.09 Abstract ( 74 )   PDF (3259KB) ( 1 )   The oases in northwest China have experienced the rapid urbanization and agricultural reclamation during the last decades. In order to investigate the effects of these land use/cover changes on regional environment,the Weather Research and Forecast (WRF) model was used in researching the Hami Oasis in this study.Two 1-month simulations were conducted separately in July with different land use/cover datasets derived from the satellite images of 2000 and 2015.Firstly,we not only used the data from the observation stations to validate the model accuracy,but also used the remote sensing retrieval data to validate the land surface temperature.The values of 2 m height air temperature were validated through the bias between the observed values and the outputs of WRF model,and the root mean square error (RMSE) between the observed values and the model outputs,the correlation coefficient (R) between the observed values and the model outputs,and the average Bias,and RMSE and R between the observed values and the model outputs were 0.4,1.7 and 84% respectively.The average bias,RMSE and 2 m height relative humidity was 1.6,5.8 and 81% respectively.The correlation coefficient of land surface temperature between remote sensing retrieval value and the model out was 87%.These results showed that our model was very reliable.Secondly,this paper investigated the 2 m height temperature,2 m height relative humidity and land surface temperature in 2000 and 2015 respectively.Comparison between the model results showed that 2 m height temperature was increased by 1.2 ℃ and the 2 m height relative humidity by 2% from 2000 to 2015 in the whole region.The 2 m height temperature was increased by 2.5-3 ℃ and the land surface temperature by 6-7.5 ℃,but the 2 m height relative humidity was decreased by 4%-8% when the land use/cover transformed from oasis to urban area.On the contrast,the 2 m height air temperature was increased by 1-2 ℃ and the land surface temperature by 3-6 ℃,but the 2 m height relative humidity was decreased by 0-4% when the desert was replaced by urban area.In addition,the 2 m height temperature was decreased by 1.5-4 ℃ and land surface temperature by 0-7.5 ℃,but the 2 m height relative humidity was increased by 4%-16% when the land use/cover transformed from desert to oasis.As a conclusion,the urban sprawl intensified the effect of the urban heat and dry island,while the oasis expansion made the oasis cool and the wet island more obvious. References | Related Articles | Metrics

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Applicability of ITPCAS and CMORPH Precipitation Datasets over Shaanxi Province WANG Yu-dan, CHEN Hao, LIU Can-ran, DING Yong-jian 2018, 35 (3):  579-588.  doi: 10.13866/j.azr.2018.03.10 Abstract ( 816 )   PDF (2533KB) ( 655 )   Compared with the precipitation data from meteorological stations,the precipitation products based on remote sensing can be used to well present the spatial distribution of precipitation,whereas the accuracy of remote sensing products generally cannot match that of the meteorological stations.Thus it is necessary to evaluate the common used precipitation products.In this paper,the reliability of two satellites precipitation products ITPCAS and CMORPH with high spatial-temporal resolution over Shaanxi Province was evaluated using the observed data from 36 national and 23 regional meteorological stations.Analysis based on the indexes including the detection rate of precipitation events,capture rate over all precipitation magnitudes and errors of precipitation at different spatial-temporal scales were adopted in the evaluation.Results showed that the ITPCAS was accurate for the Shaanxi region because of its low bias of average daily precipitation,low false alarming ratio and missed ratio,high capture rate of precipitation for grades higher than moderate magnitude,good presentation of the distribution and variation pattern of the precipitation.The spatial distribution and change pattern of precipitation in the Shaanxi region could be well presented by ITPCAS precipitation.CMORPH also showed the spatial distribution pattern of precipitation in the Shaanxi region.However,the errors were comparatively higher as CMORPH did not merge any data from meteorological stations.Further revisions of the CMORPH are needed to ensure the accuracy of the products. References | Related Articles | Metrics

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Extreme Values of Temperature and Precipitation in Southeast Shanxi Province ZHANG Hong-ying, LI Yu-fu, LIU Yao-wen, ZHANG Rui-ting, PEI Kun-ning 2018, 35 (3):  589-596.  doi: 10.13866/j.azr.2018.03.11 Abstract ( 82 )   PDF (3041KB) ( 2 )   In this paper, the daily temperature and precipitation data from 16 counties and cities in southeast Shanxi Province (Changzhi City and Jincheng City) in nearly 40 years from 1976 to 2015 were used to analyze the spatiotemporal variation of extreme temperature and extreme precipitation. The purposes of the study were to reveal the extreme degree of weather and climate in the study area and grasp the variation range of meteorological factors and their discrete characteristics of spatiotemporal distribution. The results showed that extreme precipitation and extreme temperature were obviously regional. ① The extreme temperature was generally in an increase trend in the past 40 years. The study revealed that the extremely high value of temperature (40.2 ℃) occurred in Licheng County, and the extremely low one (-27.7 ℃) in north Qinyuan County. Viewed from the temporal distribution, the extreme maximum temperature occurred mainly during the period from late May to late July, and its highest frequency occurred in late June; the extreme minimum temperature occurred during the period from late December to next mid-January, and its highest frequency occurred in January; ② The maximum intensity of extreme precipitation during the period of 1976-1915 was in a significantly increase trend. In the recent 40 years, the maximum daily precipitation (221.2 mm) occurred in Jincheng. According to the spatial distribution of extreme precipitation, its low value occurred in the southeastern region of the province, and its high values in the northwestern and southern regions. The annual extreme precipitation occurred mainly in July and August, especially in early and late July; ③ There were the 4-year quasi-periods of extreme maximum temperature fluctuation, a 12-year ones of extreme minimum temperature, and 15-year and 8-year ones of annual precipitation fluctuation in the past 40 years; ④ The abrupt change of extreme temperature was significant, but that of extreme precipitation and extreme minimum temperature was not. References | Related Articles | Metrics

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Uncertainty of Evapotranspiration Products Based on Fusion of Multi-source Remote Sensing Data and Land Surface Modes in Xinjiang CUI Jun-jie, BAI Jie, ZHENG Lei, LI Yu-zhen, ZHAO Hong-fei, YUAN Xiu-liang, LI Long-hui 2018, 35 (3):  597-605.  doi: 10.13866/j.azr.2018.03.12 Abstract ( 907 )   PDF (1721KB) ( 817 )   Evapotranspiration(ET)is an indispensable part of water resources consumption in arid region,and it is also one of the key indicators used for assessing water resources.As the vegetation here is extremely sparse and has relatively high spatial heterogeneity,it is a challenge to accurately estimate ET in arid region.Most of the common ET products based on fusion of multi-source remote sensing data and land surface modes showed the different ET results in arid region.The results of different ET products with eddy covariance(EC)measurements were generally compared in previous studies,but the issues of spatial scale mismatch between EC data and ET products are unresolved yet.It is difficult to obtain the true values of ET in large scale.The sources of uncertainty may be from the different model structures,calculation methods,forcing datasets,and so on.In this paper,three cornered hat(TCH)methods without requiring a priori knowledge of the observed ET values were used to estimate the uncertainties of ET output in Xinjiang based on the Common Land Model(CoLM),Global Land Evapotranspiration Amsterdam Model(GLEAM)and Moderate Resolution Imaging Spectroradiometer ET products(MOD16).The results showed that the spatial patterns of GLEAM and MOD16 ET products were similar,and the ET values in the mountains were significantly higher than that in the plains.The ET values of CoLM in the Altay and Tianshan mountains were significantly higher than that in the plains.In addition,the mean annual ET values in Xinjiang during the period from 2000 to 2014 differed markedly,and they were(142.36±11.11)mm·a-1,(126.66±19.12)mm·a-1 and(78.64±4.61)mm·a-1 obtained by the GLEAM,CoLM and MOD16 respectively.The CoLM and MOD16 products revealed that there was no significant decrease trend in ET during the period from 2000 to 2014(-1.03 mm·a-1 and -0.24 mm·a-1 respectively,P>0.05).The GLEAM product showed that there was no significant increase trend in ET(0.02 mm·a-1,P>0.05).The uncertainty based on the TCH method of CoLM was the highest(24.18 mm·a-1)in Xinjiang,that based on the GLEAM was moderate(21.58 mm·a-1),and that based on the MOD16 was the lowest(17.66 mm·a-1).In the shrub lands,Tianshan Mountains and semi-humid region,the uncertainties of CoLM(33.47,30.46 mm·a-1 and 32.11 mm·a-1)were significantly higher than those of GLEAM(28.31,24.73 mm·a-1 and 24.19 mm·a-1)and of MOD16(9.50,14.80 mm·a-1 and 14.34 mm·a-1).It was crucial to quantify the uncertainty of regional ET based on the CoLM,GLEAM and MOD16 ET products for accurately estimating water consumption and providing appropriate ET product for long-term water cycle change in Xinjiang.The method used in this paper might provide a reference for analyzing the uncertainty. References | Related Articles | Metrics

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Variations of Extreme Temperature in Turpan City,Xinjiang during the Period of 1952-2013 LV Ting, WU Sheng-li, LIU Qiang-ji, XIA Shi-shu, GE Huan-huan, LI Jing-long 2018, 35 (3):  606-614.  doi: 10.13866/j.azr.2018.03.13 Abstract ( 70 )   PDF (5244KB) ( 2 )   In this paper,the variations of 10 kinds of extreme temperature indices were analyzed based on the daily minimum and maximum temperatures at Turpan Weather Station during the period of 1952-2013 by using the linear method,moving average,Mann-Kendall test,Morlert wavelet analysis and principal component analysis.The results are as follows:① Six indices including the maximum and minimum air temperatures and the summer days,hot and warm nights and warm days were all in an increase trend with rates of 0.07 ℃·(10a)-1,1.31 ℃·(10a)-1,2.15 d·(10a)-1,5.15 d·(10a)-1,5.65 d·(10a)-1 and 2.04 d·(10a)-1,while the four indices including the ice days,frost days,cold nights and cold days were all in a decrease trend with rates of -0.61 d·(10a)-1,-5.49 d·(10a)-1,-6.09 d·(10a)-1 and -2.12 d·(10a)-1,respectively; ② The results of mutation analysis showed that there was no mutation of extreme maximum temperature,and the mutation of extreme minimum temperature occurred in 1984,while the mutations of absolute index occurred in the end 1980s,early 1990s and early 21st century,and the mutations of relative index happened in the end 1990s and the early 21st century; ③ There were about 28-29 a main recycles of maximum and minimum air temperatures,and about 12-29 a main recycles of cold and warm nights with high variable ratios;④ The results of principal component analysis showed that the first principal component accounted for 50.63% of the variance contribution rate,and the minimum air temperature,hot nights,frost days,cold nights,warm nights,cold days and cold nights affected significantly by the temperature change in Turpan.In general,both the highest and lowest temperatures in Turpan were in an increase trend,the latter increased more significantly than the former.The warming index increased but the cold index decreased significantly,the temperature in Turpan was in an increase trend,the change trend of extreme temperature in Turpan was consistent with the that in whole China and Xinjiang,the rangeabilities of summer days,frost days and hot nights were higher than those in whole Xinjiang and the extreme temperature index in China.The Arctic Oscillation (AO) and urbanization process were the main factors affecting the extreme temperature anomaly in Turpan,the hot and cold fluctuations were mainly caused by the extreme temperature events,which had an impact on the crop growth and yield,regional development,economic structure,and plant diseases and insect pests as well as the human activities and social sustainable development.The results could provide the theoretical basis for the sustainable development of local agriculture and for preventing meteorological disasters in Turpan.Because of the shortage of research sites,in this paper the change of extreme temperature indexes was analyzed just from the time scale rather than the spatial scale. References | Related Articles | Metrics

Biological Resources

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Spatiotemporal Variation of Vegetation Cover in the Pastoral Area in Northwestern China during the Period of 1981-2015 MOU Le, LU Yi-xiao, YANG Hui-min, FENG Qi-sheng 2018, 35 (3):  615-623.  doi: 10.13866/j.azr.2018.03.14 Abstract ( 954 )   PDF (3644KB) ( 948 )   The major parts of pastoral area in northwest China are generally the arid and semiarid regions,and the vegetation in this area is extremely sensitive to environmental change and susceptible to human activities.In recent years,the vegetation in the arid pastoral area is changed obviously,which is affected by the production of agriculture and animal husbandry and the ecological construction.Therefore,it is vital to further understand the vegetation variation in the pastoral area in northwest China,where the national ecological projects and planting structure adjustment of agriculture are implemented,and the theoretical supports are provided for the production of agriculture and animal husbandry and the ecological construction.In this study,the GIMMS 3 g NDVI product with a spatial resolution of 8 km × 8 km during the period from 1981 to 2015 was used to reveal the spatiotemporal characteristics of vegetation change in the study area with the Theil-Sen Median trend analysis,Mann-Kendall test and Hurst index.The results showed that the typical vegetation in the arid pastoral area was changed significantly during the period from 1981 to 2015,and the improved area accounted for 41.9% of the total area.The improvement of vegetation was the most obvious from 2006 to 2015,and the improved area occupied 63.7% of the total.All the 11 vegetation types were in a regenerating trend,in which the largest share came from cultivated vegetation,the improved area occupied more than 80% of the total,and the improved areas of pasture and hassock were over 60%.In the past 35 years,the vegetation coverage in the arid pastoral area was tended to a sustainable and positive development,and the proportion of continuously regenerating area was higher than 70% of the total.During the period of 2006-2015,the regeneration and stability occurred in 63.8% of the total area.National ecological projects and planting structure adjustment of agriculture affect significantly the vegetation cover in the arid pastoral areas in northwest China.In the future,the vegetation coverage is supposed to be continuously restored. References | Related Articles | Metrics

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Effects of Snow Cover and Arbuscular Mycorrhizal Fungi Network on the Seedling Growth of Erodium oxyrrhynchum WU Nan, ZHANG Jing, WANG Yue, YIN Jin-fei, ZHANG Yuan-ming 2018, 35 (3):  624-632.  doi: 10.13866/j.azr.2018.03.15 Abstract ( 785 )   PDF (1293KB) ( 732 )   Compared to other desert ecosystem,snow cover in winter in the Gurbantunggut Desert is relatively stable and thick.Moisturizing and warming effects of snow cover provide the good conditions for the growth of desert ephemeral plants.However,the desert ephemeral plants can make use of favorable conditions in early spring of two months to complete the whole process of their rapid growth.They have an important role in the formation and succession of plant community as well as sand-fixation.The well-developed herbaceous layer in the Gurbantunggut Desert is mainly related to the existence of stable snow cover in winter.A comprehensive understanding that the ephemeral plant-arbuscular mycorrhizal fungi (AMF) how to respond to the changes of snowfall and snow cover in winter is the key to reveal the stability and maintenance mechanism of desert ecosystem under the climatic and environmental changes.However,it is not clear whether there is an interaction between AM fungi and snow cover change,and how about the growth and reproductive characteristics of ephemeral plants response to the interaction. Erodium oxyrrhynchum is a typical dominant desert ephemeral plant species growing in deserts in the Junggar Basin in north Xinjiang.Our research was carried out at the ecosystem in the Gurbantunggut Desert on the basis of long-term monitoring of plots.A dual influence of physical factor (snow cover) and biological factor (AMF) on the seedling growth of dominant desert ephemeral plants was verified based on the altered treatments of field snow cover (snow cover removal,snow cover addition and natural snow cover left in place),on-site mycorrhizal treatments (PVC tube rotated and static) and analysis in laboratory.A dual influence of snow cover removal-PVC rotated treatment on the seedling growth of E.oxyrrhynchum was detected.The results are as follows: ① In non-mycorrhizal treatment (rotated PVC tubes),the leaf traits of E.oxyrrhynchum were lower than that under the mycorrhizal treatment (static PVC tubes).The snow cover removal (-S) treatment exacerbated the above difference.Compared to the snow cover addition (+S) treatment,the leaf area and leaf perimeter under the -S treatment were reduced by 70.92% and 37.26% respectively; ② Other surveys echoed the conclusions that the non-mycorrhizal treatment restricted the plant growth.In non-mycorrhizal treatment,the plant height and root length of E.oxyrrhynchum were also lower than that under the mycorrhizal treatments.Plant height was decreased by 40.45% under the (+S) treatment and by 39.47% under the (-S) treatment.Root length was also decreased by 47.75% under the (-S) treatment; ③ The non-mycorrhizal treatment was also suggested to impede the biomass accumulation.In non-mycorrhizal treatment,both aboveground and underground biomasses were lower than that under mycorrhizal treatments.The snow cover removal (-S) treatment exacerbated the above difference.Under the-S treatment,the aboveground and underground biomasses were decreased by 80.32% and 65.74% respectively.In conclusion,the dual ecological influence of non-mycorrhizal treatment and-S treatment was found to impede the seedling growth of desert ephemeral plants of E.oxyrrhynchum.Our results could provide the scientific data for speculating the adaptation mechanism of desert ephemeral plants under winter precipitation change. References | Related Articles | Metrics

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Effect of Burial on Seed Germination Traits of 10 Ephemeral Plant Species ZHANG Ling-wei, LIU Hui-liang, SHENG Jian-dong 2018, 35 (3):  633-639.  doi: 10.13866/j.azr.2018.03.16 Abstract ( 49 )   PDF (3253KB) ( 1 )   Seed germination of 10 ephemeral plant species under burial treatment and their relationship with seed mass and seed shape were tested.The aims were determined at the aspects of the population regeneration strategies and ecological mechanisms of the ephemeral plant species in the Junggar Desert.The results showed that the seed mass and seed shape were significantly different among the species.The germination percentages and rates of all the fresh matured seeds were very low,indicating that most fresh matured seeds of the ephemeral plant species had dormancy.The germination traits of the 10 ephemeral plant species under a 9-month burial treatment were significantly different.Based on their germination patterns,the plant species were divided into three types:improving type (Eremopyrum triticeum,Alyssum desertorum,Neotorularia korolkovii,Plantago minuta,Plantago cornuti and Glaucium squamigerom),inhibiting type (Trigonella arcuata) and constant type (Ceratocephalus orthoceras,Euclidium syriacum and Descurainia sophia).There were no significant correlations between the germination percentage and germination rate and the seed mass for the fresh matured seeds and burial treatment seeds,however,there were the positive correlations between the germination percentage and germination rate and the seed shape for the fresh matured seeds and burial treatment seeds.It could be concluded that the germination traits and dormancy release mechanisms differed among species,and the population regeneration strategies and ecological mechanisms of the species were vital under natural selection in desert.This conclusions are greatly useful for conserving and regenerating ephemeral plants under severe environment in desert. References | Related Articles | Metrics

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Physiological Response of Annual Desert Plants to Soil Nitrogen ZHANG Yong-mei, HUANG Gang, TANG Li-song, XU Zhi-cai, FAN Lian-lian 2018, 35 (3):  640-647.  doi: 10.13866/j.azr.2018.03.17 Abstract ( 65 )   PDF (1205KB) ( 1 )   Seasonality of available soil nutrient has an important effect on plant life history,plant growth and interspecies relations.It can be confirmed that the seasonal variation of soil nitrogen affects the process of flowering phenology,plant growth and biomass allocation of Malcolmia scorpioides and its interspecies relations with Descuminia sophia.In this study,the seasonal variation of available soil nitrogen was tested and simulated under three nitrogen treatments,i.e.the uniform,spring and summer nitrogen application modes,and the values of flowering phenology,plant height,biomass allocation and leaf nutrient content of M.scorpioides under three nitrogen treatments were measured.The growth situations of M.scorpioides plants potted alone and planted in a mixed way with D.sophia were compared,and the effects of different nitrogen application modes on the interspecies relations were analyzed.The main results are as follows:① The process of flowering phenology of M.scorpioides was significantly affected by the nitrogen application modes,and the curves of flowering amplitude of M.scorpioides plants potted alone were unimodal under uniform and spring nitrogen application modes but bimodal under summer nitrogen application mode.Cultivation ways affected significantly the process of flowering phenology of M.scorpioides.The flowering peak of M.scorpioides plants planted in a mixed way was 4-5 days earlier under the uniform nitrogen allocation mode,and the flowering proportion at flowering peak was 16% higher that of plants potted alone; ② There was no a significant interaction effect of nitrogen treatments and cultivation ways on the growth of M.scorpioides.The height of M.scorpioides plants potted alone was higher under spring nitrogen application mode than that under the uniform and autumn nitrogen application modes.Under the mixed environment,there was no significant effect of different nitrogen treatments on the plant height,aboveground biomass,underground biomass,total biomass of individual plants and root-shoot ratio of M.scorpioides; ③ There was no significant effect of nitrogen application mods and cultivation ways on the TN,TP and TN∶TP ratio in leaves of M.scorpioides.The competitiveness of M.scorpioides was higher than that of D.sophia when these two plant species were planted in a mixed way.The study results revealed that the seasonality of available soil nitrogen affected the phenological process,growth and community composition of desert herbs. References | Related Articles | Metrics

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Effects of Grazing on the Seed Production of Caragana pygmaea WANG Yue, WANG Li-hong, WANG De-kai, XIE Li-na, LI Qing-fang, MA Cheng-cang 2018, 35 (3):  648-652.  doi: 10.13866/j.azr.2018.03.18 Abstract ( 42 )   PDF (1121KB) ( 1 )   In order to understand the effect of grazing intensity on the seed production of Caragana pygmaea,the flower and fruit characteristics of C.pygmaea under different grazing intensities in Inner Mongolia,China were measured,which included the phonological period of sexual reproduction of C.pygmaea,flower number,flower biomass,coefficient of flower variation,sexual reproduction input of flower,pod number,total seed number,etc.Results showed that grazing treatments did not affect significantly the phonological period of sexual reproduction of C.pygmaea; grazing reduced significantly the flower number,flower weight and sexual reproduction input of flower,but it did not influence the coefficient of flower variation significantly.Besides,grazing reduced significantly the number of young pods and the seed number in pods,thus the total seed number of C.pygmaea was decreased.These results indicated that grazing could significantly reduce the seed production of C.pygmaea.In addition,the abortive rate of florescence was the highest under heavy grazing,which indicated that the life stage from florescence to young pods was a bottleneck for seed production of C.pygmaea.Therefore,the grazing intensity during florescence of C.pygmaea should be appropriately decrease. References | Related Articles | Metrics

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Impacts of Plant Diseases and Insect Pests on Tree Height Growth of Pinus sylvestris var.mongolica Plantations on Sandy Land ZHOU Yan-ping, LEI Ze-yong, ZHAO Guo-jun, HAN Yan-gang, ZHANG Yan-song, YU De-liang 2018, 35 (3):  653-661.  doi: 10.13866/j.azr.2018.03.19 Abstract ( 50 )   PDF (1827KB) ( 1 )   The first generation introduction of Mongolian scots pine (Pinus sylvestris var.mongolica) plantations on sandy land has been implemented in Zhanggutai in northwest Liaoning Province,China,and the final felling regeneration stage has been reached after the plantations grow for more than 50 years.In this study,the tree height growth of the first generation of Mongolian scots pine plantations on sandy land was summarized,and a theoretical basis was provided for further studying and analyzing the impact of plant diseases and insect pests on the tree height growth.The 14 candidate models were selected to fit the tree height-age relationship based on the data from 31 temporary sample plots of Mongolian scots pine plantations on sandy land located in Zhanggutai in northwest Liaoning Province,China.The models were evaluated and tested to identify the best model for the growth of Mongolian scots pine plantations on sandy land.Furthermore,the best model and the data of analytic trees suffered from plant diseases and insect pests were used to fit the individual tree height growth process.The annual growth and average growth of the plantations suffered from plant diseases and insect pests and those of the initially-protected mature plantations were calculated to provide some references for further studying and analyzing the impact of plant diseases and insect pests on tree height growth.The results indicated that the Richards model was adopted to develop the models for the tree height growth of Mongolian scots pine plantations on sandy land.A best fitting of the Richards model was achieved among the 14 candidate models to predict the tree height of Mongolian scots pine plantations on sandy land,which provided the most accurate of predicting the tree height growth with the lowest mean absolute error (MAE),residual sum of squares (SSE) ,root mean square error (RMSE) and the highest coefficient of determination (R2).Moreover,the Richards model could also be used to make an efficient fitting to the tree height growth of the plantations suffered from plant diseases and insect pests.After compared the predicted curves of tree height growth of the healthy plantations and the plantations suffered from plant diseases and insect pests,it was found that the Mongolian scots pine plantations about 16 years old on sandy land in the study area began to suffer from plant diseases and insect pests.The disturbance of plant diseases and insect pests could reduce 30.57% average maximum of tree height of Mongolian scots pine plantations on sandy land compared with the healthy plantations.As a result the maturity of initially-protected plantations could advance for 6 years,and the tree height of the plantations suffered from plant diseases and insect pests was decreased by 27.92%.However,the impact of plant diseases and insect pests on the maximums of annual growth and of average growth of the 16-year-old Mongolian scots pine plantations was not so significant in Zhanggutai. References | Related Articles | Metrics

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Response of Vegetation Coverage to Climatic Factors in the Middle Reaches of the Shiyang River in Growing Season ZHANG Yong, YANG Zi-hui, WANG Li, KANG Ying 2018, 35 (3):  662-668.  doi: 10.13866/j.azr.2018.03.20 Abstract ( 43 )   PDF (1265KB) ( 2 )   In this paper,the MODIS-EVI monthly data were used to calculate the values of vegetation coverage in the middle reaches of the Shiyang River in growing season during the period from 2006 to 2015. The interannual variation of vegetation coverage and its response to climate factors were investigated.The dimidiate pixel model (DPM) was used to calculate the values of vegetation coverage,and the interannual variation of vegetation coverage at different levels in the study area was extracted.The results showed that the low vegetation coverage was mainly distributed in the middle reaches in the 10 years,which was closely related to the interannual variation of precipitation in the same period.Secondly,the trend analysis was used to calculate the dynamic changes of vegetation coverage during the monitoring period.The results showed that the vegetation coverage in the middle reaches was increased,and its increase rate was 0.041·(10a)-1.Significant increase of vegetation coverage occurred in the oasis-desert ecotone.Finally,the correlations between vegetation coverage and temperature and precipitation in growing season were analyzed by correlation analysis.The results showed that the correlation between vegetation coverage and precipitation in growing season was higher than that between vegetation coverage and temperature,and the average partial correlation coefficients were 0.14 and -0.05 respectively.The desert-oasis ecotone was significantly correlated with climatic factors. References | Related Articles | Metrics

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Taxonomy of Lichen Family of Candelariaceae in Xinjiang Juldez Serik, Gulnaz Sahedat, Abudula Abbas 2018, 35 (3):  669-676.  doi: 10.13866/j.azr.2018.03.21 Abstract ( 58 )   PDF (2855KB) ( 1 )   The purpose of this study was to investigate the diversity of the lichen family Candelariaceae in Xinjiang.Two genera of Candelariaceae,i.e.Candelaria A.Massal (1852) and Candelariella Müll.Arg (1894),were studied,the Candelariaceae species were identified by the morphological anatomic observation.The results of chemical spot tests revealed that one species of Candelaria and six species of Candelariella were found.Among them,Candelariella antennaria Rsnen (1939),C.kansuensis H.Magn (1940) and C.vitellina (Hoffm.) Müll.Arg (1984) are the new species for Xinjiang.Newly recorded species were described and discussed according to their morphological,anatomical,chemical and ecological characters.Photos of the thallus,apothecia,asci,ascospores and paraphyses were also offered,and the morphological images of common species were given.Based on the analysis of morphological characteristics,the taxonomic keys to Candelariceae from Xinjiang were presented. References | Related Articles | Metrics

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Evaluation on Ecological Security of Coal Mining and Fragile Ecological Compound Area:A Case Study in Shanxi Province LIU Xiu-li, GUO Pi-bin, ZHANG Bo, GUO Shu-fen, JIA Yi 2018, 35 (3):  677-685.  doi: 10.13866/j.azr.2018.03.22 Abstract ( 61 )   PDF (1703KB) ( 1 )   The issues of ecological security in the areas with intense human activities and fragile ecology are becoming the focuses of global attention. In this paper,a case study on the ecological security in Shanxi Province,China during the period of 2000-2015 was carried out based on the emergy of ecological footprint,and the ecological security trend during the period from 2016 to 2020 was predicted using the ARIMA model.The results showed that the per capita emergy of ecological capacity in Shanxi Province was decreased from 1.48 hm2 to 1.12 hm2,but that of ecological footprint was increased from 5.92 hm2 to 13.08 hm2 during the period of 2000-2015.The ecological deficit was increased from -4.44 hm2 to -11.96 hm2.The ecological pressure index was increased from 4.55 to 11.72,and the ecological coordination coefficient was reduced from 1.19 to 1.08.The ecological security in Shanxi Province was safe during the period from 2000 to 2015.Based on the development capability of the ecological economic system,the ecological economic system in Shanxi Province had a great development potential from 2000 to 2015.The results predicted with the ARIMA model revealed that,during the period of 2016-2020,the per capita emergy of ecological capacity in Shanxi Province would be decreased from 1.08 hm2 to 0.81 hm2,but that of ecological footprint would be increased from 13.02 hm2 to 14.33 hm2.The ecological deficit in Shanxi Province would be increased from -11.94 hm2 to -13.52 hm2,and the ecological pressure index from 12.05 to 17.71,respectively.The ecological security in Shanxi Province would be extremely unsafe,and its warning level would be increased from the serious warning to the extremely serious warning during the period from 2016 to 2000.It was found that the ecological security in Shanxi Province in the future will be a key problem to be solved.The results would contribute to the strategy adjustment of regional development in Shanxi Province and be helpful to realize the transformation of resources-based economy and the regional sustainable development. References | Related Articles | Metrics

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Evolution Trend of Vegetation Coverage and Its Risk Assessment in the Bashang Region in Hebei Province SU Wang-xin, LI Zhuo, CHEN Shu-qin, LI Hai-fang 2018, 35 (3):  686-694.  doi: 10.13866/j.azr.2018.03.23 Abstract ( 58 )   PDF (1745KB) ( 1 )   As an ecological barrier for preventing the invasion of wind-blown sand and a major water source in Beijing,the Bashang region in Tianjin and Hebei Province is significant for constructing the ecological security in capital economic circle and for achieving the coordinated development of the economy,society and environment. In this study,the MODIS NDVI remote sensing data were analyzed,and the spatiotemporal change of vegetation coverage in the Bashang region during the period of 2005-2015 was identified. The analysis methods used in the study included the linear regression,coefficient of variation,R/S analysis and other mathematical methods. The results are as follows:① The regional difference of vegetation coverage was obvious in the Bashang region over the past 11 years,and the vegetation coverage increased from the west to the east;② Area of the regions with the very significant improvement and significant improvement of vegetation coverage was the largest and occupied 65.89% of the total study area. Areas of the regions with insignificant improvement of vegetation coverage and with vegetation degeneration occupied 32.28% and 1.82% respectively; ③ The holistic stability of vegetation coverage was high in the east but low in the west. The area of the regions with high stability and relatively high stability of vegetation coverage was the largest and occupied 61.32%. The areas of the regions with medium stability and relatively low stability of vegetation coverage occupied 24.35% and 14.33% respectively; ④ In the future,the areas of the regions with continuous improvement of vegetation coverage,potential vegetation degeneration,continuous vegetation degernation and potential improvement of vegetation coverage would occupy 59.48%,38.67%,1.04% and 0.82% respectively. References | Related Articles | Metrics

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Land Use Change in the Three-River Headwaters in Recent 40 Years XU Qian, LI Qi, CHEN Dong-dong, LUO Cai-yuan, ZHAO Xin-quan, ZHAO Liang 2018, 35 (3):  695-704.  doi: 10.13866/j.azr.2018.03.24 Abstract ( 822 )   PDF (2406KB) ( 1296 )   In this study,the ArcGIS 10.0 spatial statistical analysis and the qualitative and quantitative methods were used to analyze the spatial distribution,dynamic change and future trend of land use/cover change in the three-river headwaters based on the 1∶100 000 land use dataset from 1980 to 2015.The purposes of the study were to solve the problems of degeneration of grasslands,soil erosion and environment deterioration in the study area.The results are as follows:① Land use change was significant during the whole research period.The main land use change was divided into three periods: a degeneration of grasslands occurred during the first 15-year period (1980-1955),the land use change was slow during the second 15-year one (1995-2000),and the degenerated grasslands were regenerated during the last 15-year one (2000-2015); ② During the period from 1980 to 2015,the areas of grasslands with low and high coverage,waters and construction land were enlarged in a fluctuation way,the area of unused land (sandy land,saline land,swamp,etc.) was reduced significantly,the areas of grasslands with moderate coverage and woodlands were basically unchanged,and the total area of grasslands was enlarged by 13.45% and mainly from the reduction of unused land; ③ The land use change was mainly caused by the conversion among grasslands,unused land and waters; ④ The CA- Markov model was used to predict that the total area of waters would be unchanged,the areas of grasslands with high and low coverage,unused land,cultivated land and construction land would be continuously enlarged,but the area of woodland would be reduced; ⑤ The change of population,economic structure and policy were the main reasons affecting land use change,and the supply-demand balance of ecological assets was the driving factor of land use/cover change.Therefore,it was proposed to strengthen the basic cultural construction,conserve the natural grasslands and optimize the land use and production modes so as to promote the sustainable development in the study area. References | Related Articles | Metrics

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Effects of Climate Change on Grain Production in Plain Oasis in the Yarkant River Basin ZHANG Xue-qi, Mansur Shabiti, MA Guo-fei 2018, 35 (3):  705-712.  doi: 10.13866/j.azr.2018.03.25 Abstract ( 706 )   PDF (2356KB) ( 567 )   In order to analyze the grain production situation in the study area and its response to climate change,the meteorological and agricultural data were used to analyze the climate change in recent 60 years and its effect on agricultural climate resources,sown area and per unit area yield with the linear trend,cumulative anomaly and mutation method,and a multiple linear regression equation was developed to predict the future changes in grain yield for guiding scientific farming and better serving the agricultural ecosystem.The results are as follows: ① Over the past 60 years,an obvious warming-wetting trend occurred in the study area.The temperature and precipitation increase rates were 0.24 ℃·(10a)-1(P<0.01) and 4.49 mm·(10a)-1(P< 0.05) respectively,but the sunshine duration decreased with a decrease rate of 21.06 h·(10a)-1.The temperature mutation occurred in 1996,but there were no obvious mutations in precipitation and sunshine duration; ② With climate warming,the duration of cumulative temperature ≥10 ℃ increased by 19 d,but that of negative one shortened by 8 d; ③ In addition to the negative cumulative temperature,the grain yield was positively correlated with air temperature,sunshine duration,cumulative temperature ≥10 ℃,sown area,per unit area yield and applying quantity of chemical fertilizer;④ The multiple regression model revealed that 7 independent variable factors could be used to explain the 99.70% grain yield variation without considering other factors.Climate change is conducive to expanding grain sown area and increasing per unit area yield to a certain extent. References | Related Articles | Metrics

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Morphologic Features and Forming Causes of Plant Sandpiles in Alpine Sand Land WU Wang-yang, ZHANG Deng-shan, TIAN Li-hui, ZHANG Ming-yuan, ZHOU Xin 2018, 35 (3):  713-721.  doi: 10.13866/j.azr.2018.03.26 Abstract ( 746 )   PDF (2526KB) ( 712 )   Morphology of plant sandpiles is an important reflection of ecological suitability and sand-fixing benefits of different artificial plants.Based on the explorations of the features and formation causes of sandpiles,the erosion and deposition of plant sandpiles can be instinctively compared to provide some basic reasons for selecting the sand-fixing plant species.It is also vital to reveal the relationship between alpine vegetation growth and wind-blown sand activities.The main sandpiles where five typical sand-fixing plant species were afforested in the Ketu sand land on the eastern shore of Qinghai Lake were focused on.Based on the methods of morphological fitting and sand-deposition monitoring,three-dimensional morphology of vegetation sandpiles was simulated and analyzed with the vegetation investigations and wind-blown sand observations during the period of 2015-2016.Based on the statistic results of the total and sectional deposition depths,intensity and affecting factors of wind-blown sand,we found that: ① The sandpiles with conical,hemispherical or linear shapes could form if Hippophae rhamnoides,Salix cheilophila,Pinus sylvestris,Simon poplar and Artemisia desertorum were afforested.Deep and strong sand deposition could occur on the H.rhamnoides and A.desertorum sandpiles,and the projected area and three-dimensional volume of these sandpiles were larger than those of other three light-erosive or light-depositional plant sandpiles; ② Among the eight directional sections of the sandpiles,sand deposition occurred mainly along the northeast-east-southeast directions.In consequence of significant negative correlations between depositional intensity and sediment transport rate along the same directions,the depositional intensity and direction over all the vegetation sandpiles were quite different,especially over the S.cheilophila,S.poplar and A.desertorum sandpiles.In addition,the deposition depth and intensity changed significantly along the directions of northwest,east and southeast; ③ The morphologic differences of plant sandpiles were mainly affected by vegetation growth,the sand depositional depth of H.rhamnoides and S.poplar sandpiles increased with the increase of plant height and canopy and soil crust,especially with their coupling effects.P.sylvestris and S.poplar sandpiles were strongly affected by the basal diameter and clear bole length.Furthermore,the strong west-northwest-north winter wind affected the sandpile erosion,it was also verified by the significantly negative correlations between the directional sand accumulated depth and sand transport intensity,especially for the S.cheilophila and A.desertorum.Calculated by the sand-fixing intensity and surface sediment transport intensity,we could predict the sand accumulation modulus of the five forest dunes,the H.rhamnoides and S.cheilophila forests prevented the sand most with the amount of 400-1 100 t·hm-2 because of their high afforesting density and surviving rates.In general,H.rhamnoides,S.cheilophila and A.desertorum could be chosen as the adaptive and efficient sand-fixing vegetation species with sand-fixing benefits of 40.45%,15.53% and 62.72% respectively,while the other artificial plant species demand afforesting conservation and structure optimization for their low sand-prevention effects lower than 5%. References | Related Articles | Metrics

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Identification Method of Maize Drought in Northwest Liaoning Province LIU Xiao-Jing, MA Dong-lai, ZHANG Ji-quan, CHEN Peng 2018, 35 (3):  722-727.  doi: 10.13866/j.azr.2018.03.27 Abstract ( 75 )   PDF (1135KB) ( 1 )   Identification of agricultural drought is a prerequisite for agricultural drought risk assessment and management.The key indicator for identifying agricultural drought is soil moisture content because the crop growth depends on moisture in soil in arid area.In this paper,a case study on maize drought in northwest Liaoning Province was carried out,and the whole growth period of maize was divided into six growing stages based on the information of FAO (Food and Agriculture Organization of the United Nations) and the observational data in northwest Liaoning Province during the growth period of maize for many years.The Cropland Soil Moisture Indexes (CSMIs) at different growing stages of maize were calculated using the MOD09A1 data.The correlation between CSMIs and the corresponding measured soil moisture content at 0-50 cm depth was analyzed.The results showed that all the absolute values of the correlation coefficients were higher than or equal to 0.5,and the confidence level reached 0.01.Taking the severe summer drought in northwest Liaoning Province in 2009 as an example,the CSMI indexes of maize in late-June and mid-August and at jointing and heading stages were calculated.The indexes at two growing stages were divided into four drought levels,i.e.the light drought,medium drought,heavy drought and severe drought by using the Natural Breakpoint Classification method.The drought level maps were drawn by using GIS (Geographical Information System) means.The results showed that the drought levels of maize at jointing and heading stages in northwest Liaoning Province in 2009 were mainly the light drought,medium drought and heavy drought.The area of medium drought was the largest compared with that at other two growing stages,and the area of heavy drought enlarged significantly at heading stage.Spatially,medium drought of maize occurred in Zhangwu County,Fuxin county,Kaiyuan City and north Shenyang,and heavy drought in Changtu County,Jianchang County,Beipiao City,Yi County and Linghai City,respectively.The distribution of maize drought levels in the most counties and cities in the study area was basically in line with the information of actual drought disaster situation in the same period in 2009.But there was a regional difference,for example,the drought in Chaoyang County and Jianping County might be caused by different regional climatic conditions and local disaster prevention and mitigation.The results of this study showed that the research method was feasible in identifying maize drought in northwest Liaoning Province,and could provide the technical support for the evaluation and management of agricultural drought disaster risk. References | Related Articles | Metrics

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Correlation between the Stable Carbon Isotopes in Annual Layers of Tamarix ramosissima Sand-hillocks in the Lower Reaches of the Tarim River LIU Bo, LIU Hong-ling, MU Yu-di, LI Gui-fang, HE Ya-ling, ZHUANG Li 2018, 35 (3):  728-734.  doi: 10.13866/j.azr.2018.03.28 Abstract ( 852 )   PDF (1313KB) ( 454 )   The Tarim River is located in the north of the Taklimakan Desert in Xinjiang Uygur Autonomous Region,China.The recession of groundwater level and concomitant increase of soil salinity have reduced vegetation coverage in the lower reaches of the river.Tamarix ramosissima is one of the dominant plant species in the riparian ecosystem.With the continuous growth of T.ramosissima shrubberies,sand is blocked by the formation of T.ramosissima sand,the T.ramosissima sand-hillocks with unique hierarchical structure form ultimately after a long-term interaction of sand and T.ramosissima shrubberies.T.ramosissima sand-hillocks are rich in environmental information.The sand thickness,grain size and mineral composition of the T.ramosissima sand-hillocks were analyzed.Three observation sections of Yingisu,Abdullah and Karda in the lower reaches of the Tarim River were designed to study the relationship between δ13C and carbon content in annual layers of T.ramosissima sand-hillocks and that between the morphological characteristics of T.ramosissima shrubberies and the morphological changes of T.ramosissima sand-hillocks.The results are as follows: ① The content of δ13C in the litters of T.ramosissima was gradually decreased with the increase of annual layers of T.ramosissima sand-hillocks,and there was a negative correlation between δ13C value and carbon content.The average value of δ13C of the measured samples was -24.42‰,the maximum and the minimum were -22.09‰ and -25.24‰ respectively; ② As the annual layers of T.ramosissima sand-hillocks increased,the δ13C value of the T.ramosissima shrubberies was reduced year by year,and the long axis and short axis,height and spatial occupancy of T.ramosissima shrubberies and the height,length,width and spatial share of the T.ramosissima sand-hillocks were all in an increase trend; ③ There were the good correlations among the morphological parameters of the T.ramosissima shrubberies and of the T.ramosissima sand-hillocks,in which the correlations among the annual layers and the T.ramosissima shrubberies and sand-hillocks were significant,and these revealed that there was a mutual feedback effect between the promotion of the T.ramosissima sand-hillocks to the growth of T.ramosissima shrubberies and the δ13C value of the T.ramosissima shrubberies. References | Related Articles | Metrics

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Physiological Response and Drought Resistance of Seed Watermelons in Dry Sandy Land YANG Yu-miao, JIANG Zhi-rong, AN Li 2018, 35 (3):  735-742.  doi: 10.13866/j.azr.2018.03.29 Abstract ( 66 )   PDF (1185KB) ( 2 )   In this study,an experiment about breeding the new variety “Heifeng 1” and the major local variety “Jingyuan Daban” was carried out so as to enrich the study on the physiological and ecological aspects of seed watermelons and provide the scientific basis for the local introduction of the new variety.In addition,the atmospheric drought method was used to simulate drought stress with ethephon as a desiccant at 7 concentration levels,and the 6 physiological indexes of 2 kinds of seed watermelons were measured and analyzed.The results are as follows: ① The cell relative permeability,MDA content and Pro content of 2 kinds of seed watermelons were increased with the aggravation of drought stress,while the CHL content was decreased.The activities of SOD and POD were increased at first and then decreased; ② The chlorophyll a/b ratios of 2 kinds of seed watermelons were higher than 1 under all the drought stress levels,so it could be determined that both kinds of seed watermelons are sun plants,and Jingyuan County is rich in sunshine which is advantageous for the growth of seed watermelons; ③ Under the drought stress of 300-500 mg·L-1 concentration,6 physiological indexes of drought resistance were changed obviously,which revealed that the response of both kinds of seed watermelons to this concentration is the most sensitive.Moreover,the ethephon concentration for ripening seed watermelons is 100-300 mg·L-1.It should be paid great attention to that ethephon is sprayed on fruits when ripening and on the leaves when stressing drought; ④ The principal component analysis and subordinate function analysis revealed that the drought tolerance of “Heifeng 1” was stronger than that of “Jinyuan Daban”.Under the same drought stress,the osmotic regulation capability and water-retaining property of “Heifeng 1” were high,and it was feasible to introduce and widely plant in Jingyuan County. References | Related Articles | Metrics

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Temporal and Spatial Variation of Human Appropriation of Net Primary Productivity in the Middle Reaches of the Heihe River Basin LI Feng, MENG Ji-jun 2018, 35 (3):  743-752.  doi: 10.13866/j.azr.2018.03.30 Abstract ( 81 )   PDF (2632KB) ( 1 )   The human appropriation of net primary productivity (HANPP) is an important measure to evaluate the impact of land use on ecosystems.In this paper,the temporal and spatial distribution of HANPP in the middle reaches of the Heihe River Basin was estimated by Thornthwaite Memorial model,advanced CASA model calculation and statistical data,and then analyzed by the spatial correlation method.Temporally,in the case of grain yield increase year by year,the HANPP of the Heihe River Basin is fluctuated significantly,which is mainly driven by the fluctuation of precipitation.However,the HANPP ratio is at a relatively high level,ranging from 38% to 71%.Spatially,HANPP’s spatial pattern has been significantly altered.The high value of HANPP in the region has been transferred from the southern region of Minle County and Shandan County to away from Zhangye City and Shandan County.HANPP’s spatial pattern is related to the spatial pattern of actual net primary productivity.During the period from 2001 to 2013,HANPP had a positive spatial auto-correlation,which remained stable as a whole.The conclusion of this paper is of referential significance for the tradeoff of the economic development and ecological protection in the middle reaches of the Heihe River Basin as an ecological fragile area in the future. References | Related Articles | Metrics