Table of Content

15 March 2018, Volume 35 Issue 2 Previous Issue    Next Issue

Ecology and Environment in Central Asia

Select

Atmospheric Circulation Characteristics of Precipitation Anomaly in Arid Regions in Central Asia YANG Lian-mei, GUAN Xue-feng, ZHANG Ying-xin 2018, 35 (2):  249-259.  doi: 10.13866/j.azr.2018.02.01 Abstract ( 1071 )   PDF (3034KB) ( 1105 )   As a climate transition zone between the Mediterranean climate region and the East Asian monsoon region,the arid regions in Central Asia (including five Central Asian countries and Xinjiang of China) are influenced by high,medium and low latitude circulations,where the regional synoptic-climatic characteristics are widely different from those in Europe and East Asia.Central Asia has the unique and complicated topography and ecosystem patterns,such as the deserts,oases,glaciers and basins,and also has a highly representative environment of forming meteorological disasters under the influence of multiple backgrounds,multiple factors and multiple scales.These regions have abundant solar-heat energy,high evaporation and dramatic temperature change.Moreover,the precipitation in Central Asia is scarce and has extremely uneven distribution,but its value in the western and central parts of the Tianshan Mountains is high.Over the last one hundred years,a warm-wet trend occurred in the Tianshan Mountains.Precipitation in the eastern part (Xinjiang) of Central Asia was significantly increased under the active effects of low value system in Central Asia together with the high,medium and low latitude circulation systems.Currently,the studies are inadequate at the aspects of the regional peculiar circulation system,occurring regularity and formation mechanism of disastrous weathers,high-resolution regional numerical model,effects of land-atmosphere interaction on regional weather and climate change due to the insufficient construction of integrated meteorological observation network.Correspondingly,to carry out these studies is of the essential scientific significance and strategic value for the sustainable social and economic development along the Silk Road Economic Belt. References | Related Articles | Metrics

Select

Spatiotemporal Variation of Wetting or Drying in the Arid Regions in Central Asia HU Zeng-yun, HU Ru-ji, ZHOU Qi-ming, CHEN Xi, YIN Gang, QIAN Jing 2018, 35 (2):  260-268.  doi: 10.13866/j.azr.2018.02.02 Abstract ( 4 )   PDF (1821KB) ( 0 )   In the past 100 years,a global warming with regional difference occurred,which induced the dry regions became drier and wet regions became wetter.As one of the major arid regions in the world,the drying and wetting changes over the arid regions in Central Asia played an important role in ecosystems in these regions.The global monthly Palmer Drought Severity Index (PDSI) was applied to explore the spatiotemporal characteristics of the drying and wetting trends over the arid regions in Central Asia during the period of 1950-2014. The results showed that a weak wetting trend was obtained in these regions,and such trend became more significant after the 1980s.A nonlinear trend with a 3-7 year period was found according to the ensemble empirical mode decomposition (EEMD) method,which was consistent with the multi-periodic precipitation variation in Central Asia.A drying trend occurred in the five countries in Central Asia but a wetting trend in northwest China,which was consistent with the variation trend of precipitation over these regions.In addition,the results revealed that it was not true that the “dry regions become drier,and the wet regions become wetter” in Central Asia. These findings provide the important scientific bases for the water sources utilization and the sustainable development of ecosystem. References | Related Articles | Metrics

Select

Progress of Study on Variation of Atmospheric Water Cycle Factors over Arid Region in Northwest China YAO Jun-qiang, YANG Qing, MAO Wei-yi, LIU Zhi-hui 2018, 35 (2):  269-276.  doi: 10.13866/j.azr.2018.02.03 Abstract ( 805 )   PDF (941KB) ( 1013 )   The arid region in northwest China is one of the most sensitive areas to global change.Global warming accelerates water cycle,causes obviously the change of water cycle in atmosphere.In this paper,the characteristics of water cycle in atmosphere and the related scientific problems in the arid region in northwest China were analyzed based on the data analysis and the newest research results.The daily temperature,precipitation and relative humidity data from 96 meteorological stations in the study area were analyzed by the Mann-Kendall test and linear trend.The analyzed results showed that water vapor and precipitation experienced a sharp increase in the late 1980’s,however,such sharp increase trend has been replaced by an obvious decrease since the 21st century.Water vapor and precipitation over the east of northwest China decreased obviously due to the weakening of monsoon intensity.It was sensitive to the change of water vapor in northwest Xinjiang and the northwest of the Hexi Corridor.Proportion of the stations where precipitation increased was as high as 95.9%,especially in the Tianshan Mountains and the Qilian Mountain.Precipitation was increased significantly with the increase of elevation except that in a vertical zone from 500 to 1 500 m a.s.l.Precipitation was increased by 7 mm·(10a)-1 when the elevation was increased by 1 000 m in a vertical zone from 1 000 to 2 000 m a.s.l.,and by 10 mm·(10a)-1 in a vertical zone from 2 000 to 4 000 m a.s.l.Average water vapor balance was 2.8×1011 m3,the precipitation cycle rate was low,and the net water income in central troposphere was increased significantly.Actual evaporation was slightly decreased in the arid region in northwest China,and its reduction in the Tianshan Mountains was significant,but it was increased significantly in the Qilian Mountain. References | Related Articles | Metrics

Land and Water Resources

Select

Chemical Properties of Summer Precipitation in the Yushugou River Basin in the East Tianshan Mountains WANG Xiao-yan, JIANG Chan-wen 2018, 35 (2):  277-286.  doi: 10.13866/j.azr.2018.02.04 Abstract ( 620 )   PDF (1663KB) ( 695 )   As an effective means to study the change of atmospheric chemical composition,atmospheric precipitation chemistry could accurately reflect the local atmospheric environmental quality and air pollution.The precipitation chemical properties far away from human colonies can reflect the background value of atmospheric chemistry,and can also help us to study the atmosphere chemical conversion,transmission and the formation process and mechanism of acid rain.Restricted by the seasonal precipitation distribution and the observation conditions in drainage basin,the pH value,EC and ion composition in precipitation in the Yushugou River Basin in the east Tianshan Mountains from May to August 2013 were analyzed.The ionic sources were simultaneously investigated.The results showed that precipitation was neutral with mean pH value of 6.8.It suggested that there was no acid rain during the sampling period in the study area.The EC was in a range of 3.79-239 μs·cm-1,and it was obviously affected by precipitation.With the increase of rainfall,the under cloud wash action diluted the conductive ions in precipitation,and the precipitation conductivity decreased correspondingly.The concentrations of cations and anions were in the orders of Ca2+ > NH+4 > Na+ > K+ > Mg2+ and SO2- 4 > NO-3> Cl- >F- respectively.The cationic order was exactly the same as that of the elements in crust and different from that of cation concentration in seawater (Na+ > Mg2+ > Ca2+ > K+).It may be due to the geographic location.The Yushugou River Basin is located in an arid area where large deserts are distributed.The SO2-4/NO-3 ratio (1.76) indicated that SO2-4 was the main acid-causing substance in precipitation.The sources of the different ions in summer precipitation were different.SO2-4,NO-3,F- and NH+4 came mainly from man-made sources,such as coal burning,vehicle emission and agricultural production activities.Cl- almost came from the sea salt source and crust source.The sodium concentration was mainly affected by sea salt,and a quite part of which was from terrigenous sources.Ca2+ and K+ came from the non-sea-salt and affected mainly by the earth surface and human activities.In the study area, there were four water vapor paths including the northwest,southwest,southeast and north paths.Air mass from the northwest path originated from west Russia and Kazakhstan and passed through west Xinjiang.Water vapor originated from Mongolia passed across west Inner Mongolia with low population density and relatively underdeveloped economy.Human activities were frequent along the northwest path.There were the large deserts with alkaline soil along the northwest and north paths.Large amounts of alkaline substances were carried up to the atmosphere where alkaline substances could neutralize acid rain.Water vapor from the southwest path was from southwest inland of China and passed over the east Qinghai-Tibet Plateau.Vegetation in southwest inland grew well and less affected by human activities.Air mass along the southeast path was from the midwest region of China,and the vegetation coverage was very low,so precipitation was greatly influenced by terrigenous sources. References | Related Articles | Metrics

Select

Variation of Precipitation and Vegetation NDVI and their Effects on Streamflow in the Beichuan River Basin DONG Zhe, HE Kang-ning, WANG Gen-zhu, WANG Xian-bang 2018, 35 (2):  287-295.  doi: 10.13866/j.azr.2018.02.05 Abstract ( 5 )   PDF (3100KB) ( 0 )   The Beichuan River is the main water resource of the area around Xining City. In recent years,there was a serious ecological environment degeneration in the Beichuan River Basin because of the influence of global climate change and human activity disturbance.In this study,the streamflow data and the precipitation data during the period of 1961-2013 were analyzed,and the Mann-Kendall test was employed to detect the long-term change of precipitation and runoff volume during the study period.The spatiotemporal distribution of hydrologic features was analyzed by the Mrolet wavelet analysis method.Moreover,the remote sensing images of the vegetation NDVI data during the period from 1982 to 2013 were interpreted by RS and GIS means.Furthermore,the relationships among precipitation,vegetation and streamflow in the Beichuan River Basin were analyzed.Results showed that precipitation and vegetation NDVI in the Beichuan River Basin increased during the period from 1982 to 2013.The average annual precipitation was 518 mm and increased by 0.729 5 mm·a-1 during the period of 1961-2013.The average,highest and lowest values of vegetation NDVI were 0.365,0.385 and 0.333 respectively.Streamflow decreased during the period of 1961-2013,the average streamflow of the Beichuan River was 269 mm and decreased by 0.490 5 mm·a-1.The periodic variation of precipitation and runoff volume was different at different time scale.There was a significant positive correlation between streamflow and precipitation,and also a positive correlation between precipitation and vegetation NDVI.Human activities affected the streamflow significantly. References | Related Articles | Metrics

Select

Driving Factors Causing the Change of Runoff Volume of the Balager River in Inner Mongolia BAI Yong, GAO Rui-zhong, WANG Xi-xi, LIU Ting-xi, WANG Wei-na 2018, 35 (2):  296-305.  doi: 10.13866/j.azr.2018.02.06 Abstract ( 981 )   PDF (4760KB) ( 984 )   The Balager River Basin is a typical inland drainage basin and is located in a grassland plateau in China,where the grassland degeneration and the change of hydrological process are caused by many factors. It is very important to quantitatively analyze the variation of runoff volume,climate change and human activities for the reasonable utilization of water resources and conservation of grassland eco-environment. In this paper,the double cumulative curve,departure accumulation,improved Mann-Kendall trend test method and change rate of cumulative slope were used to quantitatively calculate and analyze the characteristics and main driving factors causing the change of runoff volume at different scales based on the hydrological,meteorological and socioeconomic data in the Balager River Basin during the period from 1959 to 2015.The following results were concluded: ① The shift point of runoff volume occurred in 1998.The runoff volume was changed under the influence of precipitation before 1998 (named as the reference period),while there were the double influences of climate change and human activities on runoff volume after 1998 (named as the variable period);② The annual,wet-seasonal and dry-seasonal runoff volumes were holistically decreased,but there was no significant precipitation variation; ③ Although there was no significant variable trend of precipitation (P=0.428) at annual scale,the runoff volume was deceased significantly (P=0.042).The runoff volume in the reference period was higher than that in the variable period when the precipitation was similar; ④ Both the runoff volume (P=0.117) and precipitation (P=0.077) decreased slightly in wet season,while the runoff volume in dry season (P=0.003) decreased significantly but the precipitation (P=0.286) did not.No matter in wet season or dry season,the average runoff volume in the reference period was higher than that in the variable period; ⑤ The monthly precipitation and runoff volume in the whole time series,reference period and variable period fluctuated similarly.The precipitation in July (107 mm) was the highest,but the corresponding runoff volume (1.7 mm) was not the highest.The highest runoff volume (2.963 mm) occurred in April because of the melting of accumulated snow cover in winter; ⑥ Compared the climate factors in the reference period with those in the variable period,the variable ranges of temperature,precipitation and wind speed were 65.12%,-16.97% and-13.3% separately,while the fluctuations of other climate factors were less than 5%.So the temperature,precipitation and wind speed were the main climate factors affecting the runoff volume; ⑦ In the study area,the primary industry,sheep number and population increased by 3.8 times,12.06% and 9% separately; ⑧ The contribution rates of runoff volume reduction due to climate change and human activities were 28.86% and 71.14% respectively,so human activities were the main driving forces causing the change of runoff volume.The study results can provide the references for analyzing the ecological hydrological change,water resources utilization and conservation in the process of socio-economic development in grassland watershed in semiarid area of north China. References | Related Articles | Metrics

Select

Water use Efficiency of Alpine Wetland Ecosystem WU Fang-tao, CAO Sheng-kui, CAO Guang-chao, HAN Guang-zhao, LIN Yang-yang, CHENG Shu-yan 2018, 35 (2):  306-314.  doi: 10.13866/j.azr.2018.02.07 Abstract ( 6 )   PDF (4332KB) ( 0 )   As the largest lake in China,the Qinghai Lake is located in the northeast Qinghai-Tibetan Plateau and a critical transitional zone where the Asian Summer Monsoon and the Westerlies meet. The lake basin belongs to a sensitive area to global climate change and is a typically fragile ecosystem.In recent years,the wetland environment around the lake is being degenerated under the influence of natural factors and unreasonable human activities.The research on water use efficiency of alpine wetlands is helpful to clarify the degree of carbon-water coupling in alpine regions and to optimize water resources management.In this study,the changes of water use efficiency and the influence of the main environmental factors on the alpine wetlands in the two growing seasons in 2015 and 2016 were analyzed based on the eddy covariance system.The results showed that the daily variation of water use efficiency decreased at first and then increased,and the water use efficiency at the mid-stage of growing season was higher than that in the early and later stages.The seasonal variation of water use efficiency at the mid-stage of growing season was higher than that at the beginning and end of growing season,the cumulative GPPs in growth season in 2015 and 2016 were 2.69 kg·m-2 and 2.17 kg·m-2,the ETs were 496.60 kg·m-2 and 466.80 kg·m-2,and the overall water use efficiency were 5.42 g·kg-1 and 4.65 g·kg-1,respectively.The analyzed results of water use efficiency and environmental factors showed that the water use efficiency of ecosystem was significantly correlated with temperature,leaf area index,monthly precipitation and soil volume moisture content,but was poorly correlated with photosynthetically active radiation and vapor pressure deficit. References | Related Articles | Metrics

Select

Variation of Soil Bulk Density,Saturated Hydraulic Conductivity and Soil Moisture Content in a Slope-gully Unit on the Northern Loess Plateau GAN Miao, JIA Yu-hua, LI Tong-chuan, MAO Na, ZHAO Ming-yang 2018, 35 (2):  315-324.  doi: 10.13866/j.azr.2018.02.08 Abstract ( 1104 )   PDF (1634KB) ( 893 )   Gully is an important kind of erosional landform in watershed on the northern Loess Plateau and has a profound effect on the surface processes,such as the hydrological,vegetational,geomorphologic and ecological processes.In order to clarify the response of three soil physical parameters (soil bulk density BD,saturated hydraulic conductivity Ks and soil moisture content SMC) to the gully topographical conditions,slope position and soil depth,in this study three sampling transects at the bottom,edge and nearby bank of an erosional gully were designed,and 40 sampling sites were designed.At every site,the undisturbed soil cores were sampled at three soil layers: 0-10 cm,10-20 cm and 20-30 cm,and they were regarded as surface,sub-surface and shallow soil layers respectively.The data of BD,Ks and SMC were obtained using the constant water-head method and oven-drying method.The results are as follows: ① Topographical conditions significantly or highly significantly affected the values of BD,Ks and SMC,and these three parameters fluctuated in a wave-like trend along the slope length.The BD values at the gully edge and bank were decreased slightly with the increase of slope length.Except the soil surface on the gully edge,the SMC on the downslope was significantly higher than that at the middle and upper slope; ② On the gully edge and bank,the variation trend of Ks and BD at different soil layers was opposite to that at the gully bottom; ③ At every soil-depth layer,SMCs on the gully edge and bank were significantly different from those at the gully bottom,and they were always lower on the gully edge than those on the gully bank.The results mentioned above indicated that the spatial pattern of BD,Ks and SMC on the slope were changed with the distribution of gully,and the influence of specific topographical conditions of the slope-gully unit on the soil physical parameters could not be neglected. References | Related Articles | Metrics

Select

Change of Ice Volume in the Qilian Mountains During the Period from 2000 to 2010 GAO Yong-peng, YAO Xiao-jun, AN Li-na, LI Xiao-feng, GONG Peng, QI Miao-miao 2018, 35 (2):  325-333.  doi: 10.13866/j.azr.2018.02.09 Abstract ( 4 )   PDF (1527KB) ( 0 )   It is of great value for systematically understanding the change of glaciers and water resources to monitor the glacier change on regional scale,especially the change of glacier mass balance.Based on the corrected SRTM and ASTER stereoscopic data,in this study the geodetic method was used to research the change of ice volume in the Qilian Mountains during the period from 2000 to 2010.The results are as follows:① The spatial matching error and spatial resolution relative error of the multi-source remote sensing DEM data were corrected,and the results revealed that the overall errors were small suitable for estimating and studying the glacier volume change and glacier mass balance on large spatial scale; ② The average decrease of glacier thickness in the Qilian Mountains during the period from 2000 to 2010 was(5.68±2.76) m,the average glacier mass balance was(-0.48±0.23) m w.e·a-1,and the change of glacier volume was(-1.59±0.72) Gt; ③ The changes of average glacier mass balance and glacier volume in the Shule River Basin (5Y44) were the most obvious,where the average glacier mass balance was(-0.80±0.27) m w.e·a-1,the average reduction of glacier thickness was(9.42±3.21) m,and the change of glacier volume was(-4.08±1.39) Gt.The change of glacier mass balance in the Heihe River Basin (5Y42) was the slightest,where the average glacier mass balance was(-0.05±0.21) m w.e·a-1,and the glacier volume loss in the Datong River Basin (5J42) was the least with an ice volume change of(-0.12±0.08) Gt; ④ The change of glacier volume in the Qilian Mountains was in an increase trend from the west to the east,however the glacier mass balance was in a decrease trend from the west to the east.Temperature increase was still a major factor resulting in glacial change. References | Related Articles | Metrics

Select

Historical Floods and Their Recurrence Intervals in Yulin Cave, Hexi Corridor MA Ling, WANG Nai-ang, JIA Peng 2018, 35 (2):  334-339.  doi: 10.13866/j.azr.2018.02.10 Abstract ( 4 )   PDF (1193KB) ( 0 )   Field observations and measurements of historical floods at Yulin Cave in the year of 1911 were conducted.The flood area was measured using a Leica TS06 Total Station,and the integration method was used to calculate flood area.The stage-discharge and slope-area methods were applied to calculate the peak discharge,and the rank method was used to calculate the recurrence intervals.Peak discharge values calculated by the stage-discharge and slope-area methods were 879 m3·s-1 and 738 m3·s-1 respectively.These two results were similar,and their difference was only 9.6%.Therefore the mean value of 809 m3·s-1 was taken as the estimated peak discharge. Furthermore,the calculations using the rank method suggested that a recurrence interval for the flood magnitude in the year of 1911 was 105 years. This work extended the flood record period for the Yulin River,and could provide a reliable basis for constructing flood control facilities at Yulin Cave in the context of global warming. References | Related Articles | Metrics

Biological and Biological Resources

Select

Research Progress of Community Structure and Ecological Functions of Phyllosphere Microorganisms LIU Yan, XU Zhi-cai, TANG Li-song 2018, 35 (2):  340-345.  doi: 10.13866/j.azr.2018.02.11 Abstract ( 705 )   PDF (722KB) ( 720 )   Phyllosphere and rhizosphere of plants are two unique and complex ecosystems with rich microbial components,and play an important role in promoting plant growth,enhancing plant disease resistance and stress resistance.Over the past decades,rhizosphere attracted many microbiologists and botanists,especially some research progresses were achieved at the aspects of rhizospheric microorganisms in promoting plant growth and enhancing the effect and mechanism of plant disease resistance.Comparatively speaking,the study on phyllosphere microorganisms was much more behind that on rhizospheric microorganisms.Initially,the study on phyllosphere microorganisms was focused on plant pathogenic microorganisms,so the progress of researching phyllosphere microorganisms was slow due to the limitation of technical conditions.The research on phyllosphere microorganisms was developed rapidly since the 21st century along with the development of molecular biological technique,especially the application of high-throughput sequencing technology.Recently,numerous studies proved that only a few of phyllosohere microorganisms were pathogenic,and most of them benefited plants by improving nutrients,promoting plant growth,and improving disease and stress resistance,thus a very important role of structuring plant communities and sustaining their functions was played.The objectives of this review are as follows: ① To introduce the definition of phyllosphere and the development of the methodology related to phyllosphere microorganisms as well as their biological functions and mechanisms;and ② To provide future perspectives in understanding microorganisms. References | Related Articles | Metrics

Select

Spatiotemporal Distribution Pattern of Vegetation Communities in the Middle Section of the Qilian Mountains GE Li-juan, DANG Hong, RONG Zhan-lei, GAO Yun-fei, ZHAO Chuan-yan, WANG Hong-yi 2018, 35 (2):  346-353.  doi: 10.13866/j.azr.2018.02.12 Abstract ( 604 )   PDF (1781KB) ( 1093 )   It is a precondition of regenerating ecological environment to fully understand the spatial and temporal distribution pattern of vegetation communities.In this paper,a vegetation classification was carried out based on the LANDSAT images in 4 years of 1976,1991,2001 and 2016.The classified results were used to get three landscape indexes,i.e.,the mean patch area (MPA),fractal dimension (Fd) and aggregation index (AI),which were used to analyze the degree and driving forces of vegetation habitat change.Based on the classification for 2001 and 2016,the vegetation distribution in 2031 was predicted by CA-Markov model.The results showed that human activities were the main factors resulting in the change of vegetation communities.The distribution of vegetation communities was changed a lot during the period of 1976-2016,the areas of forests and grasslands were reduced by 91 km2 and 169 km2 respectively.From 1976 to 2001,the MNAs of forests,shrubberies and grasslands were reduced by 1.22 km2,0.14 km2 and 0.16 km2,the AIs of forests,shrubberies and grasslands were decreased by 2.79,0.03 and 8.77,and the Fds of forests,shrubberies and grasslands were increased by 0.013,0.001 and 0.005,respectively.The degree of vegetation community fragmentation was serious.But from 2001 to 2016,the MNAs of forests,shrubberies and grasslands were enlarged by 0 km2,0.13 km2 and 0.02 km2,the AIs of forests,shrubberies and grasslands were increased by 2.38,0.21 and 6.55,and the Fds of a forests,shrubberies and grasslands were decreased by 0.005,0.002 and 0.002,respectively.The habitat of vegetation communities was gradually regenerated after 2001.The predicted areas of forests,shrubberies and grasslands in 2031 are 409 km2,486 km2 and 550 km2 respectively,which nearly equaled to those in 1976.A significant effect of ecological conservation policy had been achieved. References | Related Articles | Metrics

Select

Distribution of Terrestrial Arthropod Communities in and out-of Caragana Korshinskii Shrubberies under Different Site Conditions LIU Ren-tao, XI Wei-hua, ZHAO Juan, LIU Jia-nan 2018, 35 (2):  354-362.  doi: 10.13866/j.azr.2018.02.13 Abstract ( 2 )   PDF (2052KB) ( 0 )   In desertified region in Yanchi County,Ningxia,a field investigation on terrestrial arthropods was carried out by taking the pitfall trapping method in and out-of the Caragana Korshinskii shrubberies under different site conditions with and without mobile sand cover in spring,summer and autumn.It was found that: ① There was a remarkably seasonal difference in the activity distribution of dominant groups including Melolonthidae,Tenebrionidae and Formicidae families between the two kinds of sites conditions; ② In spring and autumn,there was a similar distribution of total abundance between the shrub microhabitats under the same site conditions,but a significantly (P<0.05) difference in total abundance between shrub microsites under the distinctive site conditions.In summer,there was a reverse distribution of total abundance between the shrub microhabitats under two kinds of site conditions; ③ In summer and autumn,there were no significant (P>0.05) differences in group richness and Shannon index between the shrub microhabitats under both kinds of site conditions,but a significant (P<0.05) different distribution of group richness between the shrub microhabitats from one kind of site conditions to another in spring.Likewise,the distribution of dominance index between the shrub microhabitats was found to be affected by the site conditions in each season; ④ The seasonal Sorenson index between the shrub microhabitats showed a reverse pattern between the two kinds of site conditions with and without mobile sand cover; ⑤ It was suggested that the individual distribution of taxonomical groups and related total abundance and dominance index was affected by the site conditions,shrub microhabitat and seasonal change.It was found that the shrub canopy facilitated the diversity of terrestrial arthropods. References | Related Articles | Metrics

Select

Effect of Slope Position on Phylogenetic Diversity of Plant Community A Case Study in the Xilingol Typical Steppe JIN Yi-lan, ZHU Ling, YAN Ya-yuan, DING Yong, ZHANG Qing 2018, 35 (2):  363-369.  doi: 10.13866/j.azr.2018.02.14 Abstract ( 4 )   PDF (1185KB) ( 0 )   With the wide application of molecular biology technique in ecology,the study on phylogenetic diversity and maintenance mechanism of plant community has become as the research hotspots. In this study,a case study was carried out in the Xilingol typical steppe so as to reveal the phylogenetic diversity and difference of plant community as well as the driving factors of community construction at different slope positions in a typical steppe in Inner Mongolia.In our study,the phylogenetic tree of all species in the region was constructed based on the online APGⅢ system,and the phylogenetic diversity and structure of plant community at different slope positions were quantified by phylogenetic diversity index and net relatedness index. Moreover,the soil samples were collected,the soil nutrient content,water content,pH value and mechanical composition were detected,and their effects on the phylogenetic diversity were analyzed.The results are as follows:① The phylogenetic diversity of plant community was significantly decreased with the increase of slope position,and the coarse powder content was the dominant factor in soil mechanical composition; ② The aggregation level of phylogenetic structure of plant community was increased with the increase of slope position,and the available phosphorus content in soil was the dominant factor; ③ The net relationship index at all the slope positions was higher than zero,which indicated that the habitat filtering was the dominant factor of plant community construction. References | Related Articles | Metrics

Select

Distribution and Water Use Efficiency of Halophytes in the Ebinur Lake Nature Reserve LI Hong-xia, YANG Xiao-dong, LV Guang-hui, LIU Wei-guo 2018, 35 (2):  370-378.  doi: 10.13866/j.azr.2018.02.15 Abstract ( 2 )   PDF (946KB) ( 0 )   In this paper,the relationships among soil salinity,numerical distribution of plants and water use efficiency (WUE) of halophytes along soil salinity gradient in the Ebinur Lake Nature Reserve were revealed.Three halophyte types,i.e.pseudohalophytes,recretohalophytes and euhalophytes,were chosen as the research objects,and the WUE,numerical characteristics,physiological indexes and soil salinity were analyzed by using δ13C,community investigation and laboratory experiments.The results are as follows: ① The nine soil samples collected from the study area were divided into three types,i.e.the samples with high,moderate and low soil salinity; ② There was no significant abundance difference between pseudohalophytes and recretohalophytes along soil salinity gradient,but the abundance of euhalophytes in the areas with high soil salinity was significantly higher than that in the areas with moderate and low soil salinity (P<0.05).The richness of pseudohalophytes,recretohalophytes and euhalophytes was obviously higher in the areas with moderate soil salinity than that in the areas with high and low soil salinity (P<0.05).In the areas with high and moderate soil salinity,the abundance and richness of halophytes were in an order of euhalophytes > pseudohalophytes > recretohalophytes,but in an order of recretohalophytes>pseudohalophytes > euhalophytes in the areas with low soil salinity; ③ There was no significant difference in δ13C values of pseudohalophytes along soil salinity gradient (P>0.05),but a significant difference between pseudohalophyte and euhalophytes (P<0.05); ④ Except the δ13C values of recretohalophytes were significantly lower than those of secretohalophytes and euhalophytes in the areas with moderate soil salinity (P<0.05),there was no significant change of the δ13C values of 3 halophytes in the areas with high and low soil salinity (P>0.05); ⑤ There were no significant differences in the physiological indexes,i.e.proline,soluble protein,soluble sugar and nitrate reductase activity of pseudohalophyte,recretohalophytes and euhalophytes along three soil salinity gradients; ⑥ In most cases,there were no significant changes of physiological indexes among euhalophytes,pseudohalophyte and recretohalophytes along soil salinity gradients (P>0.05); ⑦ Relationships among physiological indexes,δ13C value,abundance and richness varied from the different types of halophytes. References | Related Articles | Metrics

Select

Photosynthetic Characteristics and Response of Haloxylon ammodendron to Drought Stress in Hinterland of the Lop Nur YANG Si-rui, FAN Jing-wei, SUN Yong-qiang, LI Cong-juan, XU Xin-wen, FAN Jing-long, WANG Shi-jie, ZHANG Heng, ZHAI Zhi-zhong 2018, 35 (2):  379-386.  doi: 10.13866/j.azr.2018.02.16 Abstract ( 7 )   PDF (1254KB) ( 0 )   It is important to understand the photosynthetic process of Haloxylon ammodendron growing in the hinterland of the Lop Nur and its adaptation to environment. In this study,the photosynthetic characteristics and response of planted H.ammodendron to drought stress were revealed,and a suitable irrigation period was established.Three drought treatments were designed: i.e.the slight,moderate and heavy drought treatments.The results are as follows: ① Under heavy drought,LCP and LSP of H.ammodendron were 118.75 μmol·m-2·s-1 and 6174.79 μmol·m-2·s-1 respectively,which were the largest use of light energy in these three treatments.It means that,in an adverse environment,H.ammodendron expanded the scope of available light energy to improve the efficiency of using environmental resources; ② In the slight and moderate drought treatments after irrigation,the Pnmax values of H.ammodendron were 35.06 μmol·m-2·s-1 and 49.51 μmol·m-2·s-1,increased by 48.81% and 22.83%,respectively,and higher than those in drought.It could be seen that water supply is an important factor affecting plant growth in this region; ③ There was a long-duration midday depression of photosynthesis of H.ammodendron under drought stress,which might be an adaption to environment; ④ The difference of daily photosynthetic process between slight and moderate drought treatments was not significant,and the physiological indexes of photosynthesis were rapidly increased after irrigation.Considering to saving water,the moderate drought is the most suitable irrigation schedule. References | Related Articles | Metrics

Climate and Climatic Resources

Select

Spatiotemporal Variation of Drought in the Qaidam Basin YIN Wen-jie, ZHANG Meng-lin, HU Li-tang 2018, 35 (2):  387-394.  doi: 10.13866/j.azr.2018.02.17 Abstract ( 520 )   PDF (2523KB) ( 939 )   Using the measured precipitation and temperature data from the meteorological stations in and around the Qaidam Basin,the values of standardized precipitation index (SPI) and the standardized precipitation evapotranspiration index (SPEI) were calculated to describe the drought characteristics in the study area at different time scales. However,limited by the sparse distribution of stations,these two indexes were insufficient in evaluating the drought features in the region.Based on the globally distributed scPDSIpm data sets,in this study the Palmer drought severity index (PDSI) was used to analyze the characteristics of drought evolution and spatiotemporal distribution of drought in the whole study area.Results are as follows: ① It could be seen that the effect of temperature on drought was significant at inter-annual scale but not at monthly or seasonal scale; ② The correlation coefficients between PDSI index and the SPEI and SPI indices were higher than 0.7.In addition,PDSI was more suitable for evaluating drought in the areas without observed data; ③ As a whole,drought was the most serious in the central Qaidam Basin,and the occurring frequency of drought was low in the eastern marginal zone and the northwestern part of the study area.However,the situation had been greatly improved since 2000.This study has important guiding significance for evaluating the suitability of different drought indexes and drought evaluation in ungauged basins. References | Related Articles | Metrics

Select

Accuracy Evaluation and Seasonal Distribution of Precipitation over the Mongolian Plateau Based on TRMM Data QIN Fu-ying, JIA Gen-suo, YANG Jie, NA Yin-tai, HOU Mei-ting, BAO Yu-hai 2018, 35 (2):  395-403.  doi: 10.13866/j.azr.2018.02.18 Abstract ( 2 )   PDF (2233KB) ( 0 )   Accuracy of the latest version satellite product TRMM 3B43 V7 for precipitation over the Mongolian Plateau was evaluated based on the observational precipitation data from 134 meteorological stations,and the spatial and seasonal distribution of precipitation in recent 19 years was analyzed. The results showed that there was a significant positive correlation between TRMM and observational precipitation data at monthly scale,and the determination coefficient R2 was 0.88 (P<0.01),which indicated a good consistency between them. The inter-annual variation of annual precipitation showed a significant upward trend at the rate of 32.1 mm (10a)-1 (P<0.05) in recent 19 years. However,there were certain spatial differences:an increase trend of precipitation was observed in the northeast,north and southwest of the Mongolian Plateau,but a decrease trend in the west and southeast of the plateau and in the region west of the Greater Khingan Mountains.Regarding the inter-annual variation of seasonal precipitation,winter precipitation was in a decrease trend,while precipitation in other three seasons was in an increase trend,especially in summer and autumn,the 69.2% and 81.8% areas of the total area were in an increase trend in summer and autumn respectively.There was an obvious spatial differentiation in seasonal precipitation,the decrease of spring precipitation occurred mainly in the west of the plateau,and the significant increase of that in the eastern and northern parts of the plateau; the significant increase of summer precipitation occurred mainly in the southwestern and western-northern parts of the plateau; the significant increase of autumn precipitation occurred mainly in the southern and southeastern parts of the plateau; and the significant decrease of winter precipitation occurred mainly in the west plateau. References | Related Articles | Metrics

Select

Climatic Characteristics of Rainfall and Snowfall Days in the East Hexi Corridor YANG Xiao-ling, WANG Zong-cheng, YANG Mei, WANG He-ling 2018, 35 (2):  404-411.  doi: 10.13866/j.azr.2018.02.19 Abstract ( 3 )   PDF (2085KB) ( 0 )   According to the observed daily precipitation data from five meteorological stations in the east Hexi Corridor during the period of 1960-2016,the spatiotemporal changes,extreme values and abnormal variations of rainfall and snowfall days were systematically analyzed and summarized with climatic statistic method.The results revealed that the annual rainfall and snowfall days increased from the northeast to the southwest because of the influence of altitude,topography and weather system,and the difference of snowfall days between the north and the south was much higher than that of rainfall days.Monthly variation of rainfall days was consistent,high value occurred during the period from July to August,there was no rainfall during the period from December to next January or February.Monthly variation of snowfall days was relatively consistent,high value occurred in March,and there was no snowfall during the period from July to August.Annual and inter-annual variations of rainfall and snowfall days were different,but they were generally in an increase trend,climate trend coefficients were not examined by significance level test,and the increase trend was not significant.Time series of annual rainfall and snowfall days revealed that there were the 5-7 year and 6-8 year quasi-periodic variations respectively,and they were at the significant level of reliability α=0.05 test.Anomalies of annual rainfall and snowfall days were consistent,normal years occurrence probabilities were 64.9%-70.2% and 66.7%-73.7% respectively.Occurrence probabilities of abnormal years of rainfall and snowfall days were 29.8%-35.1% and 26.3%-33.3% respectively,and very many or very few rainfall and snowfall days would cause the serious effects on industrial and agricultural production and safety of life and property.This study could provide the scientific basis for preventing flood and drought disasters,scientifically utilizing water resources and conserving ecological environment,and could also provide the reference for studying climate change. References | Related Articles | Metrics

Select

Spatiotemporal Characteristics of Dust Weather in Qinghai During the Period of 1961-2015 LI Fan, XU Wei-xin, QI Dong-lin, YAN Ying-cun 2018, 35 (2):  412-417.  doi: 10.13866/j.azr.2018.02.20 Abstract ( 2 )   PDF (2311KB) ( 0 )   The interannual,decadal and seasonal temporal changes of dust weather were analyzed with the regression method and Mann-Kendall test based on the daily dust weather data observed by 50 meteorological stations over Qinghai Province of China during the period from 1961 to 2015,and the spatial variations of dust weather at different levles were researched using the Inverse Distance Weighting interpolation.The results are as follows: ① The dust weather days were in a decrease trend in a fluctuation way during the period from 1961 to 2015,and the annual mean dust weather days increased by 3.42 d·a-1 (P<0.01).The decrease speed of floating dust days was the highest,and that of dust storm days was the lowest.During the 55 years,the days of three kinds of dust events increased at first,and then decreased.The days of dust weather began to decrease from 1976.The abrupt change of dust weather days occurred in 1994,and dust weather occurred froquently in the 1970s with population growth and land use intensification; ② Curve of the seasonal variation of dust weather days was “V-shaped” from spring to winter,that was to say,the most dust weather days appeared in spring and winter,and then in summer and autumn.The decrease trend of the days of dust storm,blowing dust and floating dust were significantly high from November to next July (α=0.01),and slightly high from October to September (α=0.01); ③ Dust storm and float dust generally occurred most frequently in the Qaidam Basin.The center of frequent occurrence of blowing dust was in Wudaoliang south of the Kunlun Mountains,and the dust weather was dominated by blowing dust in Qinghai. References | Related Articles | Metrics

Select

Variation of Pan Evaporation and Its Affecting Factors in the West Horqin Sandy Land CAO Jing, Aramusa 2018, 35 (2):  418-424.  doi: 10.13866/j.azr.2018.02.21 Abstract ( 3 )   PDF (977KB) ( 0 )   Under the background of global warming and shortage water resources,the research on evaporation is not only conducive to understanding the variation of hydrologic cycle,but also could provide a theoretical basis for water resources planning and management.Based on the meteorological data in the west Horqin Sandy Land during the period of 1981-2016,the trends of pan evaporation and some meteorological factors,including precipitation,wind speed,temperature,cloud cover,relative humidity and vapor pressure deficit,were analyzed using the linear trend,Mann-Kendall trend and Sen’s slope tests.The main factors affecting pan evaporation were also determined by means of Partial correlation method,principal component analysis and stepwise regression analysis.The results showed that,in recent 36 years,pan evaporation and wind speed decreased significantly (P<0.001),while total cloud and low cloud were in a significant increase trend (P<0.001).Furthermore,the seasonal pan evaporation and wind speed also decreased significantly (P<0.001),while the seasonal low cloud was in a significant increase trend (P<0.001),and the decrease rates of pan evaporation in spring and summer were higher than those in autumn and winter.The result of partial correlation analysis showed that the annual and seasonal pan evaporation was more closely related to the wind speed and cloud cover.A further examination in which the principal component and stepwise regression analysis were used showed that the decrease of wind speed and the increase of cloud cover were the main meteorological factors affecting annual pan evaporation.Based on the results above,it was concluded that the decrease of wind speed and the increase of cloud cover were the main causes resulting in the decrease of pan evaporation in the west Horqin Sandy Land in recent 36 years.Additionally,the change of precipitation and relative humidity was not significant,the annual mean temperature increased (P<0.05) but the pan evaporation decreased,significantly (P<0.001),which revealed that the climate warming in the study area was significant,but the increase of aridity degree was not so obvious in recent 36 years. References | Related Articles | Metrics

Select

Affecting Mechanism of Moisture Sources of Isotopes in Precipitation in the Tianshan Mountains Based on GCMs and Ice Core YANG Sen, ZHANG Ming-jun, WANG Sheng-jie 2018, 35 (2):  425-435.  doi: 10.13866/j.azr.2018.02.22 Abstract ( 3 )   PDF (3019KB) ( 0 )   The interannual variations of δ18O from the GCMs and ice core were studied according to the six simulations of several isotope-equipped general circulation models (GCMs) (including the GISS-E(MERRA),GISS-E(NCEP),isoGSM(NCEP),LMDZ(free),LMDZ(ECMWF) and MIROC(free)) and the data of δ18O from the Miaoergou ice core. By correlation analysis,the six simulations of isotope-enabled GCMs and the δ18O data from ice core were analyzed.Six simulations of isotope-enabled GCMs data and the ice core data were involved,and the monthly series of stable oxygen isotopes in precipitation for each grid were applied to calculate the linear trends.By observing the change trend of δ18O data from ice core and simulated data,the most suitable isotope-enabled general circulation model (GCM) was selected to analyze the data of δ18O in precipitation in the Tianshan Mountains,and the sources of water vapor in the most suitable model were further analyzed.The results showed that there was a “temperature effect” in the results simulated with GCMs on an interannual timescale.Generally,the correlation between oxygen isotope composition and surface air temperature on interannual timescale was lower than on seasonal timescale.The trend of MIROC(free) model was similar to that of the Miaoergou ice core (a=-0.01).MIROC(free) model was the most suitable model used to simulate the values of δ18O in precipitation in the Tianshan Mountains,and the result from the MIROC(free) model was similar to the measured one.The direction and proportion of water vapor sources determined the poverty or enrichment degree of δ18O in precipitation.Based on the continuous wavelet transform methods,the strongest energy occurred during the period from 1990 to 2001.Even though the values of δ18O in precipitation during the period from 1990 to 2001 presented many positive fluctuations,a significant decrease trend was characterized in general.After observing the vapor source trajectories,the increased water vapor from the Arctic Ocean resulted in a significant decrease trend of δ18O in precipitation,and the increased water vapor from the mid-latitude Atlantic caused many increasingly fluctuations of δ18O. References | Related Articles | Metrics

Select

Effects of Clouds on Solar Radiation over Typical City in Arid Area CHEN Chun-mei, ZHONG Ke, CHEN Yong-hang, QIN Rong, XIN Yu, CHEN Bin, LIU Qiong, ZHOU Dai-yi 2018, 35 (2):  436-443.  doi: 10.13866/j.azr.2018.02.23 Abstract ( 2 )   PDF (1344KB) ( 0 )   The ecological environment in arid and semiarid areas is very fragile and sensitive to climate change.The change of solar radiation is very important to climate and ecological environment.The effects of clouds on solar radiation are significant.In this study,the effects of clouds on solar radiation over Urumqi,a typical semiarid city,were studied so as to provide a scientific basis for improving the accuracy of predicting climate change in the region using the data with high temporal and spatial resolution and the long-term series of Single Scanner Footprint TOA/Surface Fluxes and Clouds (SSF) dataset,CER_SSF_Aqua-FM3-MODIS_Edition3A dataset from the Earth’s Radiant Energy System (CERES) of NASA’s EOS (The NASA Earth Observing System).Another purpose of this study was to examine the annual and inter-annual variations of solar radiation,cloud physical properties and cloud shortwave radiative forcing over Urumqi during the period from January 2006 to December 2015.The results showed that the annual distribution curves of net surface shortwave radiation flux and the shortwave radiation flux at the top of atmosphere on clear day were unimodal.The peak values,187.5 W·m-2 and 792.3 W·m-2,occurred in June and May respectively.The cloud radiative forcing at both the top of atmosphere and on the surface were negative,i.e.-253.7 W·m-2 and -249.0 W·m-2 respectively.The annual distribution of cloud shortwave radiative forcing kept a downward trend.The inter-annual average values of cloud shortwave radiative forcing for 10 years were close to a symmetrical unimodal distribution.The peaks values,-391.3 W·m-2 and -355.0 W·m-2,occurred in July.Seasonally,the values were the highest in summer but the lowest in winter,and they were slightly higher in spring than in autumn.There was a similarity in annual variation of cloud physical parameters and cloud shortwave radiative forcing.The total cloud cover in winter was low,and its maximum value occurred in June.Cloud optical depth peak values,22 and 26.1,occurred in July and November respectively,and the minimum value (6.1) occurred in February.The maximum value (263.5 K) and the minimum value (242.6 K) of cloud equivalent temperature occurred in June and February separately. References | Related Articles | Metrics

Select

Variation of Snow Cover and Its Response to Climate Change in the Xilin River Basin in Recent 35 Years HAO Xiang-yun, ZHU Zhong-yuan, ZHANG Shen-wei, SONG Hai-qing, XI Xiao-kang, LIU Dan-dan, HAN Dong-dong 2018, 35 (2):  444-450.  doi: 10.13866/j.azr.2018.02.24 Abstract ( 2 )   PDF (2027KB) ( 0 )   The variations of snow cover depth and snow cover duration in the Xilin River Basin,Inner Mongolia were studied using the 35 year (from 1981 to 2016) daily meteorological data (precipitation,temperature,etc.) and the daily snow cover depth data from the Xilinhot,Abagachi,Linxi and Hexigten Banner meteorological stations.The relationships among the climate factors and the snow cover depth and snow cover duration were analyzed.Results indicated that both the snow cover depth and snow cover duration were in a slight increase trend.There were the turning points of both the snow cover depth and snow cover duration,the mutation of average annual snow cover depth occurred in 1984,but there was no significant mutation of snow cover duration.Furthermore,the change cycles of snow cover depth and snow cover duration were 10-30 years and 12-30 years respectively.There were the significant negative correlation between the snow cover depth and snow cover duration and the climate factors,such as temperature,average wind speed,sunshine duration and effective accumulated temperature in snow cover season.However,there were the significant positive correlations among the snow cover depth,snow cover duration and relative humidity.Path analysis indicated that the effect of temperature on snow cove variation was more remarkable than that of other climate factors no matter directly or indirectly.It is very import to study the variation of snow cover and its response to climate change in cold and arid areas for water resources management,agricultural development and disaster prevention and control in grassland drainage basin. References | Related Articles | Metrics

Select

Impact of Observation Error of Desert Underlying Surface Energy Flux on Energy Closure in Arid Area YANG Bin, ZUO Hong-chao, DONG Long-xiang, YANG Hai-long, CHEN Bo-long, DAI Lin-dong 2018, 35 (2):  451-460.  doi: 10.13866/j.azr.2018.02.25 Abstract ( 2 )   PDF (1537KB) ( 0 )   In this paper, the characteristics of the energy transmission near the surface layer over desert substantial underlying surface in arid area were analyzed, the study was carried out with the observation instruments, and the influence of these instruments on the surface energy balance was researched based on the observed data obtained from the Inner Mongolia Micro meteorological Observation Experiment (IM-MmOE). In designing the experiment, the observed inconsistent impact on energy closure was maximized as much as possible. The ideal underlying surface for the observation should be homogeneous, but the actual one was inhomogeneous, so the observation precision of surface energy flux was not reached an ideal level, and the influence of observation errors on the surface energy closure was widely concerned. The results showed that the surface energy transfer in the desert underlying surface in arid area was mainly dominated by sensible heat flux and surface soli heat flux. The observed correlation coefficients of the most radiation instruments were higher than 0.98, the correlation coefficients of observed surface soil heat flux and sensible heat flux were higher than 0.97, and the correlation coefficient of observed latent heat flux was the lowest and only 0.92. The mean squared errors of surface soil heat flux, latent heat flux and sensible heat flux were 14.3 W·m-2, 8.9 W·m-2 and 8.0 W·m-2 respectively, the observed data of all the instrument were consistent well, and the observation errors were low. Deviations of the observed data caused by the nonuniformity could affect directly the rate of energy closure, the observed deviations of turbulent flux (the sum of sensible heat flux and latent heat flux) caused an uncertainty of 1%-3% of the surface energy closure rate, the effective energy (the difference between net radiation and surface soil heat flux, the deviation of observed surface soil heat flux was considered only) brought about an uncertainty of 5%, and the total deviation of the data of turbulent flux and effective energy resulted in an uncertainty of 6%-8% of surface energy. References | Related Articles | Metrics

Select

Dynamic Parameterization and Simulation of Surface Albedo in Maize Cropland Mulched by Plastic Film in Arid Region LU Sha, ZUO Hong-chao, MIAO Wen-hui, CHEN Ji-wei, GUO yang, WANG Shi-xin 2018, 35 (2):  461-470.  doi: 10.13866/j.azr.2018.02.26 Abstract ( 457 )   PDF (6024KB) ( 1289 )   Based on the observed data of surface albedo in maize cropland mulched by plastic film in an arid region from June 1 to July 24,2015,the variation of surface albedo during the vegetation growth period and the relationship between surface albedo and soil moisture content were analyzed. It was found that the surface albedo variation and the correlation between surface albedo and soil moisture content were significantly different from that on underlying surface without mulching plastic film,thus a corresponding dynamic parameterization scheme of surface albedo was established.Furthermore,the modified dynamic parameterization scheme of surface albedo was applied to the land surface process model CoLM,and three simulation tests were carried out to analyze and verify the accuracy and applicability of the new scheme on cropland underlying surface mulched by plastic film.The numerical simulation results showed that the three tests could reflect the daily variation trend of land surface process,but the comparison revealed that the simulation performance of the new model was the best,because the simulation capability of the upward shortwave and longwave radiation was obviously increased,and the simulated results of soil temperature and soil moisture content in shallow soil were improved to some extent.Hence,the dynamic parameterization method of surface albedo could significantly facilitate the land surface process simulation capability on cropland underlying surface mulched by plastic film in arid region,and it could be referred in further developing and improving the land surface process models in the future. References | Related Articles | Metrics

Others

Select

Oxygen Isotopic Content in the Main Deserts (Sandy Lands) in China HUO Jun-peng, GUO Hao, GUO Cui-ping, XIN Zhi-ming 2018, 35 (2):  471-476.  doi: 10.13866/j.azr.2018.02.27 Abstract ( 2 )   PDF (618KB) ( 0 )   The widely distributed arid land in northwest China provides abundant dust for sandstorm occurrence,which causes the serious economic and social problems.It is important to monitor the change of environmental and meteorological factors and to study the desert ecosystem and desertification control.In recent years,some researchers found that dust play a positive effect on increasing the nutrient content of river and enriching the nutrient content of topsoil.So the study on provenances of aeolian sand is of not only the great theoretical and practical significance in aeolian geomorphology,but is also essential for understanding the complex linkages among dust emission,loess accumulation,climate system,and ocean biogeochemistry cycle.It is generally known that the dust sources in China are mainly the vast deserts and sandy lands in northwest China,but the specific distribution and contribution rate are unclear.Previous researchers found that the isotopic exchange of sand-sized quartz was minor under sedimentary conditions.In other words,the isotopic features of quartz will not be changed even after a number of sedimentary cycles.So this paper studied the oxygen isotopic distribution of quartz to establish a foundation for dust tracing.In order to understand the oxygen isotopic distribution of quartz in the main deserts (sandy lands) in China,seventy-five sediment samples were collected from eight deserts and four sandy lands in China,including the Taklimakan Desert,Gurbantunggut Desert,Kumtag Desert,Qaidam Desert,Tengger Desert,Ulan Buh Desert,Mu Us Sandy Land,Hobq Desert,Badain Juran Desert,Hulunbuir Sandy Land,Otindag Sandy Land,and Horqin Sandy Land during the period from 2014 to 2016.Samples were taken from 10 cm thick topsoil far away from human habitation.The samples were crushed to pass through a 200 mesh.Oxygen isotopic compositions of quartz were measured by means of isotope ratio mass spectrometry.The result showed that the quartz δ18O values varied between 7.8‰ and 14.9‰.There was a big difference in homogenization degree of internal surface sediment among different deserts (sandy lands),in which the homogenization degree in the Taklimagan Desert was the lowest,and that in the Badain Juran Desert was the highest;the spatial variation of oxygen isotopic compositions of quartz in the main deserts (sandy lands) in China was obvious. References | Related Articles | Metrics

Select

Spatial Distribution of Grain Size Composition of Surface Sediment in the Bosten Lake Region, Xinjiang PU Jia, MA Long, Jilili Abuduwaili, LIU Wen, GE Yong-xiao 2018, 35 (2):  477-485.  doi: 10.13866/j.azr.2018.02.28 Abstract ( 2 )   PDF (3940KB) ( 0 )   In this paper,the spatial distribution characteristics of grain size and its affecting factors were discussed by using the mathematical and statistical methods and analyzing the characteristics of the composition,parameters and frequency curves of grain size of surface sediment in the Bosten Lake region,Xinjiang. The results revealed that the fine silt composition was dominant in surface sediment in the lake region,and its content varied in a range of 19.2%-62.1% with an average of 40.1%. The surface sediment was holistically in a concentric-ring distribution centered on the northwest area,and extended from the northwest area to the southwest and east areas under the effects of the Qingshui River,Huangshui Stream and clockwise or counterclockwise circulating flow. With the increase of distance from the circle center,the content of fine particles increased but that of coarse particles decreased,gradually,and much clay deposited on the south bank. The results of cluster analysis showed that the sediment samples could be divided into two classes,indicating the different deposition environment:① In the broad lake region,the grain size frequency curves of surface sediment were mostly multimodel,but their shape was similar,the high peak was dominated by the particles with moderate diameter of 6-20 μm,and the low peaks were dominated by the particles of 500 μm and about 1 μm respectively,and they were in a negative skewness,showing a hydrostatic and low-energy depositional environment in the suspended transportation of the particle; ② In the estuary area,the grain size frequency curves of surface sediment were multimodel,the high peak was dominated by the particles with diameter of 70-100 μm,and even there was a secondary peak dominated by the particles with diameter of 2-10 μm,suggesting a high-energy deposition environment under the mixing effect of lake wave and river water. Through analyzing the spatial distribution of grain size of surface sediment and its affecting factors,the modern sediment environment and the hydropower conditions in the different lake areas were revealed,and the results could be referred for researching the ecological environment in the lake region. References | Related Articles | Metrics

Select

Effects of Land use Change on Carbon Reserve and Carbon Sink Value in Yanchi County LIU Shu-qin, WANG Rong-nv, XIA Chao-zong, HOU Rui-ping, CHEN Jian, ZHANG Ke-bin 2018, 35 (2):  486-492.  doi: 10.13866/j.azr.2018.02.29 Abstract ( 2 )   PDF (876KB) ( 0 )   The effect of LUCC on carbon budget of terrestrial ecosystem is one of the important contents in the research field of global climate change.In this study,the monitoring data of land use,land use change and forestry carbon sink were used to research the land use change and its carbon sink effects in Yanchi County during the period from 2005 to 2013.The results are as follows: ① The land use level in the county was below the average level of China,and its transfer activities occurred mainly among other land use types,such as the farmland,grassland and forest land; ② The carbon reserve of vegetation in the county was increased by 23.96%,the soil carbon reserve was decreased by 0.30%,and the total carbon sink value was decreased by 5.00×109 US dollars during the period of 2005-2013; ③ Enlargement of forest land was the main reason for the increase of carbon reserve in Yanchi,and the change and management of grassland were the important factors that affected the soil carbon reserve; ④ From the analyzed results of land use change,carbon reserve and its price driving,it could be found that the biggest effect on the carbon reserve in Yanchi was the transfer of land use types.Therefore,the carbon reserve in the county may be improved by considering other land use types in the future development.Moreover,the grassland and forest land management would be an important cause of carbon source/sink change in the county. References | Related Articles | Metrics

Select

Spatiotemporal Evolution of Intensive Cultivated Land use in the County-level Regions in Xinjiang Based on the PSR Model CHENG Lan-hua, YANG De-gang, ZHANG Xin-huan, ZHANG Yu-fang 2018, 35 (2):  493-502.  doi: 10.13866/j.azr.2018.02.30 Abstract ( 3 )   PDF (4833KB) ( 0 )   It is an effective way to improve the level of intensive cultivated land use scientifically and reasonably so as to guarantee the regional food security and promote the regional sustainable development. In this study,the 83 county-level regions in Xinjiang were taken as the study units,an index system was developed based on the PSR model,the entropy value method was used to determine the index weight,and the composite model of weighted summation was taken to evaluate the level of intensive cultivated land use.Moreover,the PSR system coordination model was built to evaluate the subsystem coordination of cultivated land use in Xinjiang.In Addition,the longitudinal comparison coefficient and the comprehensive comparison coefficient were introduced,the ArcGIS 10.2 spatial analysis means were used to reveal and analyze the spatiotemporal evolution of intensive cultivated land use at county scale in Xinjiang during the period from 2000 to 2013.In the end,an in-depth discussion on the factors affecting the spatial and temporal evolution of cultivated land use in Xinjiang was made using the multiple regression analysis method.The results of this study revealed that the pressure index P of whole Xinjiang was holistically promoted steadily during the period from 2000 to 2013; the state index S of whole Xinjiang was overall fluctuated and eventually decreased during the study period; the response index R of whole Xinjiang was overall fluctuated and eventually increased during the period from 2000 to 2013.On the side,it was pretty obvious that the variation trends of state index S and response index R were opposite in different periods.It was also found that the degree of intensive cultivated land use F was overall increased steadily,and the harmonization degree of cultivated land PSR system D was overall decreased in a fluctuation way in whole Xinjiang during this period.It was also pretty easy to find that the regions with an increase of intensive cultivated land use F were more than those with a decrease in the 83 county-level regions in Xinjiang during the study period.On the contrary,the regions with a decrease of harmonization degree of cultivated land PSR system D were more than those with an increase in the 83 county-level regions in Xinjiang during the period from 2000 to 2013.Most of regions were not scientifically in intensive cultivated land,as having only 15 regions with increase of intensive cultivated land use F and harmonization degree of cultivated land PSR system D in Xinjiang duruing the study peiod.The spatial difference of intensive cultivated land use in the 83 county-level regions in Xinjiang was obvious,and the spatial aggregation was developed towards a spatial balance.Some factors,such as the high-tech agricultural development,population growth,natural conditions and economic development level,affected the intensive cultivated land use to varying degrees,but the relationship between factors and intensive cultivated land use was slightly different in various years. References | Related Articles | Metrics