Table of Content

15 January 2018, Volume 35 Issue 1 Previous Issue    Next Issue

Land and Water Resources

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Global Distribution Fields of Runoff Depths Calculated by Empirical Runoff Coefficient LIANG Shu-min, YU Zhi-yuan 2018, 35 (1):  1-11.  doi: 10.13866/j.azr.2018.01.01 Abstract ( 1456 )   PDF (2158KB) ( 1487 )   In this paper,the 110-year history of the estimated global runoff volumes was reviewed.The land slope and aridity index were taken as the independent variables,the method of Ordinary Least Squares (OLS) regression was employed to estimate the runoff coefficients in typical regions,and the empirical formula of runoff coefficient was used to calculate the runoff volumes in China.Based on the empirical formula and high-resolution precipitation grid data,the Grid and Spatial Analysis module in Geographic Information System (GIS) was applied to calculate the high resolution spatial distribution fields of global water resources.Main calculated results were that the total runoff volume in the world (excluding the Antarctic Continent) was 47 884 km3,the average runoff depth was 359 mm,and the average runoff coefficient was 0.462;the runoff depth in Africa was 230 mm,the runoff coefficient was 0.345,and both were the lowest in the 6 continents; the runoff depth in South America was 770 mm,the runoff coefficient was 0.507,and both were the highest;the runoff depth in Asia was 313 mm,which was lower than the average in the world,and the runoff coefficient was 0.495,which was higher than the average in the world.The results were compared with the relevant literatures.This study emphasized the importance of groundwater runoff and groundwater increment in arid and semiarid regions,and the estimated runoff depths in these regions were increased significantly.The calculated runoff volumes in Africa and Australia were 6 944 km3 and 3 026 km3 respectively,which were obviously higher than the average of 24 estimations between 1973 and 2014 in literatures.Moreover,the authors also calculated the runoff patterns of all the 31 interior drainage areas in detail in the world.The total area of the interior drainage areas in the world was 28.47 ×106 km2,the total runoff volume was 1 663 km3,the average runoff depth was 58.4 mm,and the average runoff coefficient was 0.252.The runoff depth in the interior drainage areas in Oceania was 35 mm,the runoff coefficient was 0.129,and both were the lowest in the world.Case studies in the interior drainage areas showed that the runoff depth fields calculated by the empirical formula were in accordance with the actual runoff distribution patterns in Africa,Oceania and 4 regions in Asia,including the Nura River in Kazakhstan,Hexi Corridor and west Inner Mongolia Plateau in China,southeast Mongolia and China’s central and eastern Inner Mongolia Plateau,and the interior drainage areas in Arabian Peninsula.The theoretical hypothesis was confirmed for the interior drainage subregions,and the higher the spatial resolution was,the larger the calculated runoff value would be.Main conclusions of this study are as follows: the spatial resolution of this study was 0.166 7 degrees,and it was 3 times of the major resolutions used in the runoff calculation;the runoff volumes were calculated from the high spatial resolution runoff fields in this study,including the runoff volumes in interior drainage basins and the runoff volumes consumed in the exorheic drainage basins before flow inflowed into the oceans;the differences between the runoff volumes in this study and the actually measured runoff volumes at the debouchures to the oceans or inland lakes should be the interruptive consumption of the evaporation from natural water surface and wetlands,the net water consumption of agricultural irrigation,and the net dissipation of artificial water usage in urban and industrial regions in watershed;the groundwater runoff and the increment of groundwater and of soil available water are the main forms of runoff in arid and semiarid climate zones.In available literatures,the underestimation of water resources was mainly the ignored evaporation from natural waters and wetlands as well as the net dissipation of artificial water usage. References | Related Articles | Metrics

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Variation of Continental Glacier and Temperate Glacier in China: A Case Study of Glacier No.1 at the Headwaters of the Urumqi River and Baishui Glacier No.1 LI Kai-ming, CHEN Shi-feng, KANG Ling-fen, LI Zhong-qin, LI Sheng-de, WEN Qiang 2018, 35 (1):  12-19.  doi: 10.13866/j.azr.2018.01.02 Abstract ( 1446 )   PDF (1287KB) ( 1081 )   It is of great scientific significances and realistic values to comparatively research continental glacier and temperate glacier change.As an indicator of climate change,glacier change has attracted many researchers to pay great attentions for a long time.This paper carried out a comparative study on the changes of Glacier No.1 (a continental glacier) at the headwaters of the Urumqi River and of Glacier No.1 (a temperate glacier) in the Baishui River Basin in the Yulong Mountain under global warming since the 1950s.The results showed that the glacial mass loss and equilibrium-line altitude as well as the temperature in mobile layer increased,glacier depth thinned,flow velocity slowed down,glacier terminus retreated,and the glacier area and volume reduced.The change rate of continental glacier increased or higher than that of temperate glacier,and the change gaps of two type glaciers reduced gradually or stabilized.Further analysis revealed that the ablation and retreat of two type glaciers was mainly caused by temperature increase,and then by the reduction of ice-surface albedo,and the differences between two type glaciers were the climatic environment,sensitivity of response to climate change,the mechanism of accelerated ablation,and others. References | Related Articles | Metrics

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Ecological Risk Assessment of Polycyclic Aromatic Hydrocarbons in Water at Batou Section of the Yellow River during Freezing and Thawing Periods PEI Guo-xia, ZHANG Qi, LI Han-qing, GAO Li-hui, WANG Jing 2018, 35 (1):  20-26.  doi: 10.13866/j.azr.2018.01.03 Abstract ( 3 )   PDF (1163KB) ( 0 )   Polycyclic aromatic hydrocarbons (PAHs) consist of two or more benzenoid rings,which are highly lipophilic and hydrophobic.PAHs can be transferred through food chain,and can accumulate in biological tissues,including human body.Because of their toxicity and persistence as well as their carcinogenic,teratogenic and mutagenic properties,PAHs are a topic of growing concern.PAHs have been detected in many water bodies,including the Yellow River.While there have been many studies of PAH concentrations in water,and PAH concentrations in water during freezing and thawing periods have rarely been reported.The study area is Baotou section of the Yellow River.A global positioning system was used to record the locations of the 8 sampling sites (S1-S8) along the main channel of the Baotou section.Baotou is an industrial city on the banks of the Yellow River.As the city has developed,large quantities of industrial wastewater containing organic pollutants have been discharged into the river.In particular,huge amounts of industrial wastewater have been channeled into the Yellow River from the Kundulun,Sidaoshai,East and West rivers.The Baotou section of the Yellow River is located in a zone of 40.248 9°-42.730 3°N and 109.253 3°-111.440 3°E.Winter lasts for more than three months in a year,and the Yellow River at Baotou is frozen in winter,which means that PAHs from the atmosphere are deposited onto the ice.In light of this unique situation,the distribution of PAHs in the Baotou section of the Yellow River should be investigated.In this study,water samples were collected from eight sites along the Baotou section of the Yellow River in freezing-thawing process during the period from 2012 to 2014.By establishing the pre-processing method used in water from the study area,the information on the PAH concentrations in the Baotou section of the Yellow River in freezing-thawing process was obtained,and the environmental risk of PAHs in this area was analyzed.In this paper,the main results are as follows: There were 11 kinds of PAHs detected in water samples from Baotou section of the Yellow River.The total PAH concentrations in water samples ranged from 6.58 ng·L-1 to 222.37 ng·L-1,the mean value was 61.48 ng·L-1,and PAH concentrations were dominated by fluoranthene.Some of them were higher than the standard of EPA882-Z-99-001,and benzo〔a〕pyrene exceeded the standard of GB3838-2002 “Surface Water Environment Quality Standard”.According to the ecological risk assessment of individual PAHs,the risk probability of anthracene in water was 83.92%,when the percent of aquatic organisms affected more than 5.00%.Water phase Σ6PAH joint toxicity was higher than that of the ecological risk of anthracene largest single role toxicity,even higher than the monomer ΣPAH overlap area.According to the joint risk assessment of PAHs,the joint risk was much higher than that of individual PAHs in water phase,and there was a significant joint toxicity. References | Related Articles | Metrics

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Virtual Water Transfer and Linkages among Industries in the Heihe River Basin ZHANG Xin-xin, LIU Jun-guo, ZHAO Xu, GUAN Ying-jie 2018, 35 (1):  27-34.  doi: 10.13866/j.azr.2018.01.04 Abstract ( 3 )   PDF (1174KB) ( 0 )   Water scarcity has become as a major bottleneck for the development of arid regions in China.In particular,the contradiction between water urbanization and water scarcity has raised a lot of concerns in arid region.Virtual water,defined as the water consumption during the economic activities when producing goods and providing services,provides a new perspective for alleviating regional water scarcity.Most previous virtual water studies focused on the virtual water trade among different regions.However,less studies analyzed the virtual water transfers and linkages among different economic sectors.Under the background of “water caps on production”,it is necessary to study the water transfers and the resultant linkages in economic sectors in the form of virtual water flow.Combined with backward and forward linkages in economic analysis,in this study an environmental input-output method was used to analyze virtual water transfers and linkages among economic sectors in terms of water consumption.Both blue water (surface water and groundwater) and green water (rain water) consumptions were considered as the physical water input into the economic sectors.This physical water was then converted to virtual water and redistributed in the economic system.A case study was carried out in an arid region consisting of Ganzhou District and Linze and Gaotai counties (GLG) in the Heihe River Basin,China.The Heihe River Basin is the second largest inland river basin in China.The GLG region is the main consumer of water resources,accounting for over 90% of total water consumption in the Heihe River Basin.The results showed that total direct blue water consumption in 2012 was 5.96×108 m3.About 57% of the total direct blue water consumption for primary sector was transferred into secondary sector and tertiary sector.While only 19.5% and 3% of that for secondary sector and tertiary sector were transferred into other sectors,respectively.The total direct green water consumption was 1.29×108 m3,and about 57% of that was transferred into other sectors.This results also explained why agriculture had such high blue water consumption,accounting for 97% of total in GLG.This is because the virtual water transfer increased the virtual water demand of both secondary and tertiary sectors,as a result,the water consumption of primary sector was driven by both secondary and tertiary sectors.The combination of virtual water transfer and virtual water trade analysis showed that the volumes of 2.66×108 m3 of blue virtual water and of 0.59×108 m3 of green virtual water were transferred from primary sector to secondary and tertiary sectors,and then exported to the regions outside GLG.This volume of virtual water accounted for 80.6% of virtual water transferred out from primary sector.These results manifested that most of virtual water transfer from primary sector was used for the production of exported goods and services.The previous Backward Linkage and Forward Linkage Analysis were adapted in this study to reflect the virtual water transfer impact,so the Backward Linkage was further decomposed as the sum of Backward Transfer Linkage and Internal Redistribution,while the Forward Linkage was further decomposed as the sum of Forward Transfer Linkage and Internal Redistribution.The results showed that “Agricultural” had the single largest Forward Transfer Linkage among 40 sectors considered,while“Other Manufacturing”,“Food and Tobacco Processing”,“Transport and Communications” and “Hotel and Restaurant” were the sectors with the largest Backward Linkage.We suggested the linkage among the sectors above with agricultural sector should be decoupled to avoid the expansion of agricultural water consumption.This can be achieved through the compensation from the upstream sectors which used the agricultural products as raw materials.Finally,it was concluded that the considered virtual water transfers and linkages among sectors can support the regional decision-making in industrial restructuring and water resources management,and is an effective support to the fulfillment of “water caps on production”. References | Related Articles | Metrics

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Simulation of Rainstorm Flood Peak Discharge in the Qinghe River Basin in Xi’an Based on SWMM Model LIU Chun-chun, LIU Wan-qing, ZHANG Yue, WANG Tao, YANG Bo, YU Lei 2018, 35 (1):  35-42.  doi: 10.13866/j.azr.2018.01.05 Abstract ( 3 )   PDF (1438KB) ( 0 )   In order to discuss the applicability of storm water management model for flood peak discharge simulation in mountainous area,in this paper the Qinghe River Basin in Xi’an was taken to carry out a case study on flood peak discharge using the traditional lumped model and the semi-distribution model. The semi-distribution model was based on DEM and drainage basin system to develop the SWMM model.Two different modes of hydrological models could be validated by the peak discharge during several typical rainfall episodes in 2016.The results showed that the lumped pattern was in good fitting with the measured values,the relative error was only 6%,and the deterministic coefficient was 0.871.In order to further test the applicability of the lumped model,the results were satisfactory from the perspective of runoff process.The relative errors of the two rainfalls were 11%,and the certainty coefficient and Nash coefficient of the two rainfalls were higher than 0.8,which revealed that the good results were achieved in the simulation.Therefore,the lumped hydrological model based on SWMM is suitable for simulating the runoff discharge in the Qinghe River Basin.At last,the runoff processes in the drainage basin under different recurrence periods were simulated.The flood peak discharge occurred about 1.5 hours after starting rainfall,and the change of runoff discharge will be relatively stable during the following decade.This model has a certain application value to the local water conservancy department in assessing extreme rainfall events. References | Related Articles | Metrics

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Method and Application of Situ-measuring Soil Phosphorus in Arid Area Using Diffusive Gradients in Thin Film(DGT) Harlhax Yibat, LI Qing-jun, ZHANG Yan 2018, 35 (1):  43-49.  doi: 10.13866/j.azr.2018.01.06 Abstract ( 3 )   PDF (1015KB) ( 0 )   The performance of diffusive gradient in Thin Film Technique (DGT) for the situ-accumulation of bioavailable elements in natural waters,sediments and soil was investigated in recent years,it could represent the in-situ state of soil solution,the nutrient elements were not changed in the process of sampling and extracting susceptible interferences,and the elements of effective supply of plants could be represented. This study was conducted to evaluate the effects of environment factors on the migration and bioavailability of DGT in soil after phosphate fertilizer was applied. Pot experiments were performed to study the influence of time,temperature and relative soil moisture content on the bioavailable phosphorus. The mobility of phosphate fertilizer in 4 soil types including alluvial soil,anthropogenic-alluvia soil,gray desert soil and meadow soil was determined throughout the surface dressing and drip fertigation using DGT. Results showed that DGT-P was increased with the time (0 hour and 24 hours) and tended to be stable after 24 hours. DGT-P was increased with the increase of relative soil moisture content from 20% to 100%,and the highest DGT-P content was found when the relative soil moisture content varied in a range of 80%-100%. In addition,DGT-P tended to increase with the increase of temperature,and it became stable when the temperature was higher than 25 ℃. Compared with surface dressing,drip fertigation of phosphate fertilizer could be used to increase the DGT-P content in soil layer of 10-15 cm in depth. The migration of DGT-P content was also affected by soil types and texture,the highest migration of phosphorus occurred in meadow soil (71% sand),and the lowest one in alluvial soil (46.65% sand). Our present study indicated that the DGT technique can be successfully used in measuring soil bioavailable phosphorus in 24 hours under the conditions of relative soil moisture content of 80%-100% and temperature of 25 ℃. It was also found that,compared with surface dressing,drip fertigation of phosphate fertilizer could be used to increase the migration of phosphorus. References | Related Articles | Metrics

Weather and Climate

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Photosynthetically Active Radiation in Alpine Wetland in the Qinghai Lake Watershed GAO Li-ming, ZHANG Le-le, CHEN Ke-long, MAO Ya-hui 2018, 35 (1):  50-56.  doi: 10.13866/j.azr.2018.01.07 Abstract ( 1901 )   PDF (1115KB) ( 710 )   Photosynthetically active radiation (PAR) is an important parameter in the process of ecosystem. However,there are few reports on the change of PAR in alpine wetland. In this paper,the characteristics of PAR variation in the alpine wetland were analyzed based on the radiation data from the Xiaobohu and Wayanshan wetland meteorological stations in the Qinghai Lake Basin.The results showed that the annual global radiation (Q) and PAR at Xiaobohu Meteorological Station were 6 711.6 MJ·m-2 and 2 888.3 MJ·m-2,but they were 5 963.4 MJ·m-2 and 2 527.5 MJ·m-2 at Wayanshan Meteorological Station,respectively.The values of Q and PAR at the Wayanshan station were significantly lower than those at the Xiaobohu station.The daily and seasonal variations of both Q and PAR values at the two sites were obvious,and the maximum values of Q and PAR occurred around 13:00 o’clock.The maximum Q and PAR values appeared in June,and the minimum ones in December.The average annual photosynthetically active radiation coefficients (ηPAR) at the Xiaobohu and Wayanshan stations were 0.43 and 0.44 respectively.The seasonal variation of ηPAR at both sites was also obvious,the maximum value appeared in July,and the main reason was that the water vapor content over the Qinghai Lake Basin was the highest in July.Finally,a statistical model was developed based on the clearness index (Kt) and total solar radiation (Q) data at the Wayanshan station so as to estimate the PAR values in the whole Qinghai Lake Basin.The model was also verified at the Xiaobohu station,the results showed that the model could be used to meet the requirements of estimating the PAR values under different weather conditions in the Qinghai Lake Basin. References | Related Articles | Metrics

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Spatiotemporal Variation of Precipitation in the Fenhe River Basin during the Period of 1971-2011 ZHANG Chen, WANG Cui-hong, YAN Jun-xia, LI Hong-jian, KANG Na, GAO Zong-qiang 2018, 35 (1):  57-67.  doi: 10.13866/j.azr.2018.01.08 Abstract ( 5 )   PDF (2938KB) ( 0 )   The Fenhe River Basin is located in a semiarid and semi-humid region.As the main replenishment source,precipitation could exert the significant impact on the ecological environment and socioeconomic development in this basin.A dataset of monthly precipitation series (from 1971 to 2011) from 154 precipitation stations was used to analyze the spatiotemporal distribution of annual precipitation,precipitation in spring (from March to May),summer (from June to August),autumn (from September to November) and winter (from December to next January) as well as flood season (from June to September) in the whole Fenhe River Basin (FHRB) and its upper reaches (TUR),middle reaches(TMR) and lower reaches (TLR) during the period of 1971-2011.The geostatistical analyst module of GIS was used to compare and select the optimal interpolation model,and the nonparametric Mann-Kendall (MK) statistical method was used to test the trend and abrupt change.The study results are as follow: ① There were the similar spatial distribution patterns of annual precipitation and rainfall in summer and flood season in FHRB,TMR and TLR,the precipitation was in a decrease trend from the south to the north and from the mountainous areas to the basins,and the lowest rainfall value occurred in the central Taiyuan Basin.In spring and winter,the trend of isohyets was from the east to the west with a decrease trend from the south to the north.In autumn,the trend of isohyets was from the northwest to the southeast with a decrease trend from the southwest to the northeast.Spatial distribution of precipitation was homogeneous in spring and winter in TUR,while annual precipitation and rainfall in summer,autumn and flood season was high in the western mountainous areas than that in the eastern mountainous areas and central valley areas; ② As a whole,there was a negative trend of annual precipitation and rainfall in summer and flood season,but a positive trend of precipitation in spring,autumn (including TUR) and winter in FHRB,TMR and TLR.On the contrary,there was a positive trend of annual precipitation and rainfall in summer and flood season,but a negative trend of precipitation in winter in TUR.The liner trends of annual precipitation,precipitation in spring,summer,autumn,winter and flood season in FHRB during the period from 1971 to 2011 were -6.0 mm·(10a)-1,5.3 mm·(10a)-1,-10.0 mm·(10a)-1,6.6 mm·(10a)-1,0.2 mm·(10a)-1 and -7.2 mm·(10a)-1 respectively.All the decrease or increase trends were not significant (P>0.10); ③ Abrupt changes of annual precipitation and rainfall in summer,autumn and flood season were detected during mid-late 1970s,most of which occurred in 1979.After the abrupt years,precipitation trends were mainly negative but not reached the significant level (P>0.05).In spring,abrupt changes of precipitation were detected in 1973,and the positive trend reached a significant level (P< 0.01) in the 1980s.In winter,abrupt changes of precipitation were detected in 1973 in FHRB and TLR but in 1979 in TUR and TMR,and the negative trend reached a significant level (P<0.05) in 1999. References | Related Articles | Metrics

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Spatiotemporal Variation of Temperature and Precipitation in Northwest China in Recent 54 Years SHANG Sha-sha, LIAN Li-shu, MA Ting, ZHANG Kun, HAN Tuo 2018, 35 (1):  68-76.  doi: 10.13866/j.azr.2018.01.09 Abstract ( 1259 )   PDF (1800KB) ( 1221 )   Based on the temperature and precipitation data from 191 meteorological stations in northwest China during the period from 1961 to 2014,many methods,such as the linear trend,running means,accumulative anomaly and IDW,were used to study the spatiotemporal variation of temperature and precipitation in northwest China. The results showed that the average temperature was in an increase trend,especially in winter.The trend of extreme maximum temperature and extreme minimum temperature was similar to that of average temperature.Precipitation was also in an increase trend,especially in recent years.Precipitation occurred mainly in summer,in particular,the precipitation in winter increased sharply since the 21st century.The high annual temperature occurred mainly in south Xinjiang and the southeast Qilian Mountains,especially in the Junggar Basin and the southwest Tianshan Mountains.Precipitation decreased gradually from the east to the west.More precipitation occurred in the southeast Qilian Mountains,and its low value occurred in south Xinjiang.Precipitation increase was significant in the west Tarim Basin and north Xinjiang.Viewing from the spatiotemporal variation of temperature and precipitation,there was a warming-wetting trend in northwest China. References | Related Articles | Metrics

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Responses of Grassland Productivity to Climate Change in the Yunwu Mountain in Recent 20 Years LUO Rui-min, GUO Liang, CHENG Ji-min 2018, 35 (1):  77-84.  doi: 10.13866/j.azr.2018.01.10 Abstract ( 1185 )   PDF (1482KB) ( 736 )   It is important to study the relationship between grassland productivity and climate change so as to carry out the rational countermeasures for regenerating the vegetation and ecology in the Yunwu Mountain. The grassland productivity,potential climate productivity trend and their correlations with climate change were analyzed based on the long-term climatic data and productivity records of Yunwu Mountain grassland on the Loess Plateau during the period of 1992-2011. The results are as follows: ① In recent 20 years,the mean annual temperature increased significantly,and the temperature increase in winter and early spring was higher than that in summer. There was no significant trend of annual precipitation,however,rainfall in July decreased significantly; ② Warming and drought in summer resulted in the decrease of productivity and potential climate production of the grassland,while the temperature increase in winter restricted the increase of grassland productivity; ③ The utilization ratio of climatic resources in the study area was 53%,which indicated that about another half of potential productivity needed to be further developed. Proper use and improvement of natural grassland and development of artificial pastures will further increase the productivity of the grassland on the Loess Plateau. References | Related Articles | Metrics

Application Climate

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Time Series Area of the Ayakkum Lake and Its Response to Climate Change LI Jun-li, BAI Jie, WANG Ya-jun 2018, 35 (1):  85-95.  doi: 10.13866/j.azr.2018.01.11 Abstract ( 1888 )   PDF (6528KB) ( 1238 )   In order to analyze the annual,monthly and spatial variations of arid lake extent change under climate change,the Ayakkum Lake in the Alkin Mountains in Xinjiang,China was selected as an example to map the changes of lake area and level based on the time series of Corona and Landsat images in recent 50 years.The results showed that the change of the Ayakkum Lake experienced 3 stages,i.e.the periods of 1964-2004,2005-2010 and 2011-2014,and the annual change rates of their lake area were -0.012 km2·a-1,-0.256 km2·a-1 and -4.798 km2·a-1 respectively.Holistically,the lake area was shrunk gently at first and then significantly,lake water was firstly found to be extinct on September 25th,2014,and its ecological function was weaker and weaker.The seasonal variation of the Chaiwopu Lake extent revealed that the lake water extent reached its peak in spring and was shrunk down to its valley in autumn,the seasonal change became more obvious,and its sharp shrinkage occurred after 2005.Monthly lake area curves showed that the Chaiwopu Lake was lost its water area rapidly year by year.The variation of the Ayakkum Lake was highly similar to that of the Chaiwopu Lake.Before 2005,the change of lake water area and water level was insignificant.After 2005,the lake water area was sharply shrunk.When these lakes was shrunk to their bottoms in 2012,the groundwater level in the study area was highly correlated with the variation of lake water area.In the wet years between 1999 and 2004,the lake shrinking rate was decreased,but a dynamic water balance of the Chaiwopu Lake was kept.Excessive groundwater pump after 1993 was the main reason of lake extinction,which resulted in the ecological disasters in this region. References | Related Articles | Metrics

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Evolution of Drought in China during the Period of 1961-2012 DONG Ting, MENG Ling-kui, ZHANG Wen 2018, 35 (1):  96-106.  doi: 10.13866/j.azr.2018.01.12 Abstract ( 2 )   PDF (3768KB) ( 0 )   Drought is a complex natural hazard,and it is affected by many factors.Climate change brought about by global warming causes the intensification and increased frequency of drought,which triggers negative economic,social,and environmental impacts.Drought occurs frequently in China,resulting in considerable impacts and economic losses.The long-term ground-based observation data,meteorological drought indices and the non-parametric Mann-Kendall trend test were used to study the drought evolution in China during the period from 1961 to 2012.Drought monitoring worldwide has significantly progressed through various drought indices,such as the Standardized Precipitation Index (SPI) and Standardized Precipitation Evapotranspiration Index (SPEI).The calculation of the SPI values is based on the statistical probability derived from precipitation data.The SPI can be flexibly designed to quantify the precipitation anomaly for a specific time period based on the long-term precipitation records for specific drought types.The SPEI is an improved drought index based on both precipitation and potential evapotranspiration (PET) data.SPEI considers the effect of reference evapotranspiration on drought severity,and retains the simplicity multi-scalar nature of the SPI which allows for the identification of different drought types.The multi-scale SPIs and SPEIs (e.g.,1,3,6,9,or 12 months) from all available weather stations were calculated using the long-term monthly precipitation and mean temperature data during the period from 1961 to 2012.The characteristics of drought including the frequency and its distribution as well as the proportion of area affected were analyzed based on these two meteorological drought indices.Results showed that SPI and SPEI with short timescales showed a high temporal frequency of dry and moist periods.The spatial patterns of drought severity change implicated by SPI and SPEI were basically alike,and these two indices could be used to characterize the regional drought conditions effectively.Additionally,the SPEI performed better in drought monitoring than the SPI,largely because the SPI values are based only on precipitation data,while the SPEI ones were based on both precipitation and temperature,and the very warm temperature during those decades may have an influence on the SPEI values.The SPEI values identified 17 drought events in both Guizhou and Ningxia during the period from 1961 to 2012,and the average durations of drought episodes in these two areas were 3 and 4.7 months respectively.The frequency distribution of drought showed that,compared with other time periods,drought occurred more frequently during the period of 2001-2010.The Mann-Kendall trend test was used to detect the trend of in situ reference data.A downward trend at high confidence levels was detected at 38 stations,and a nonsignificant downward trend of average precipitation was detected at most stations.The increase trend of mean temperature at high confidence levels and significant drying trend (in terms of the SPEIs) were detected at most of the stations in north China (Inner Mongolia,Hebei and Shanxi),northeast China (Liaoning,Jilin and Heilongjiang),northwest China (Shaanxi,Gansu,Ningxia,north Qinghai and southeast Xinjiang) and southwest China (southeast Sichuan,Yunnan,Chongqing and Guizhou).The drought area was in a significant enlargement trend in most of these zones. References | Related Articles | Metrics

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SPH-based Numerical Calculation of Sand Grain Velocity Distribution in Wind-blown Sand Flow JIN A-fang, Maimtimin Ayni, HU Guo-yu, XIONG Min, MA Xiao-jing 2018, 35 (1):  107-113.  doi: 10.13866/j.azr.2018.01.13 Abstract ( 6 )   PDF (2247KB) ( 0 )   The wind-blown sand movement is a kind of air-sand two-phase flow problem.Under the action of air flow,sand grains experience a lift-off when they are changed from static state to movement.The research on lift-off of sand is very important in physics of wind-blown sand,and the distribution of the lift-off speed and the lift-off angle are the main physical factors and play an important role in deciding the motion state of sand in air.There are three types of sand movement in air flow,such as creep,suspension and saltation.Among them,the saltation accounts for about 75% of the wind-blown sand movement types.Tomaster mechanism of saltation can help us understand the law of wind-blown sand movement,and it can be used to further improve the study on the physics of wind-blown sand.There are two main reasons for the lift-off of sand,i.e.,fluid starting driven directly by air flow and the impact starting caused by other sand grains.Speed distribution function of sand can reflect the information of the macro-scale movement and the micro-scale movement in wind-blown sand movement.To determine the speed distribution function of the sand can work out the various macro-scale statistical variables.The Smoothed Particle Hydrodynamics (SPH) method,a Lagrange Particle method,was applied in this paper to dissect the mathematical model of wind-blown sand movement.The air and sand phases are dissected to single particles.The status of dissected sand grains was consistent with their natural status,so the sand movement can be accurately described.It is very simple and accurate to deal with the collision role by setting smoothing length.SPH method was firstly applied in the numerical simulation of gas-solid two-phase flow in this paper.In this study,the numerical simulation of wind-blown sand movement near the ground surface was performed to observe the micro-scale motion of sand,and to reveal the interaction mechanism of air flow and sand. References | Related Articles | Metrics

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Applicability of Meteorological Drought Indices in Drought Monitoring in the Qinghai Plateau LI Hong-mei, LI Lin, LI Wan-zhi 2018, 35 (1):  114-121.  doi: 10.13866/j.azr.2018.01.14 Abstract ( 6 )   PDF (5748KB) ( 0 )   The 114 drought cases in the Qinghai Plateau during the period from 1986 to 2013 and the monthly,seasonal and annual SPI,PA,K and MCI indexes during the period from 1981 to 2015 were used in this study.The annual and seasonal consistencies of meteorological drought and actual drought were compared,and the characterization capabilities of different drought indexes for the typical drought events were evaluated.The main conclusions were as follows: ① The SPI and K indexes could be used to well monitor the inter-decadal variation of the total occurring frequency of drought,the drought-monitoring capability of SPI was the highest,and then that of K,and that of PA and MCI was poor; ② The SPI and K indexes could be used to well monitor the spring drought and summer drought,but the results of monitoring autumn drought and winter drought were unideal.The seasonal drought-monitoring results of PA and MCI indexes were significantly different; ③ The SPI index could be used to monitor the occurrence and degree of drought.There was some deviation in drought degree between the K and PA indexes,but a significant deviation in both the drought degree and extent based on MCI index; ④ The results based on SPI and K indexes were more reasonable to describe the process of drought,but those based on PA and MCI indexes did not accord with the drought occurrence and development; ⑤ Taken together,SPI index was optimal used to monitor spring drought and summer drought,then K index,and PA and MCI indexes were poor in monitoring the spring drought and summer drought. References | Related Articles | Metrics

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Influence of Dust on Snowpack in the Tianshan Mountains YANG Tao, GUO Ling-peng, HUANG Fa-rong, LI Qian, LI Lan-hai 2018, 35 (1):  122-129.  doi: 10.13866/j.azr.2018.01.15 Abstract ( 3 )   PDF (1528KB) ( 0 )   Snowpack is an important source of water resources in arid area in northwest China. In spring,dust storm weather occurs frequently in the basins around the Tianshan Mountains. Dust deposition on snow cover surface from dust storm can reduce the reflectance of snow cover,increase the solar radiation absorption on snow cover surface,and accelerate snowmelt. It is necessary to study the effects of deposited dust on the dynamic change of snowpack in the Tianshan Mountains for better water resources management in the region. In this study,a simulation experiment of the influence of dust deposition on the dynamic change of snowpack in snowmelt season was carried out at the Tianshan Station for Snow and Avalanche Research. Four treatments,i.e. the natural conditions,2 g·m-2,4 g·m-2 and 8 g·m-2 dust deposition with three replicates,were designed for the field experiment. The experiment was started on March 4 and ended on March 11. After observing and analyzing the physical characteristics of snowpack,the results indicated that snowmelt in the snowpack was significantly affected by dust deposition. The snow grain size on snow surface was increased with the time,and the more dust deposition there was,the larger the snow grain size but the lower the snow reflectance would be. The snowmelt rates under the treatments with 2 g·m-2,4 g·m-2 and 8 g·m-2 dust deposition were increased by 22.36%,46.05% and 76.90% compared with that of natural snowpack,respectively. The results of the study could provide the references for simulating the dynamic change of snowpack and managing water resources in arid area in northwest China. References | Related Articles | Metrics

Plant Resources

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Water Use Process of Constructive Plants in Desert Riparian Forest CHEN Ya-ning, LI Wei-hong, CHEN Ya-peng, ZHOU Hong-hua, HAO Xing-ming, ZHU Cheng-gang 2018, 35 (1):  130-136.  doi: 10.13866/j.azr.2018.01.16 Abstract ( 1145 )   PDF (1812KB) ( 1660 )   Desert riparian forest is an important component of the ecosystem in arid area.The study on the water use process of constructive plants in desert riparian forest is of great significance to formulate the countermeasures for ecological conservation and restoration in arid area.In this study,the arid lower reaches of the Tarim and Heihe rivers in northwest China were taken as the study areas to explore the plant water resources and root hydraulic lift process of desert riparian forest plants,and the water use processes of Populus euphratica and Tamarix ramosissima growing under drought stress were analyzed.The results indicated that water use pattern and survival strategy of desert riparian forest plants are various under different groundwater depths and drought stress conditions in the lower reaches of the Tarim and Heihe rivers.In plant water acquiring,P.euphratica and T.ramosissima use mainly deep subsoil water and groundwater,but their water absorption is more diversified in the lower reaches of the Tarim River than in the lower reaches of the Heihe River; In water distribution,P.euphratica growing in the lower reaches of the Tarim River generally has strong hydraulic lift capacity and significant ecological effect on water redistribution.The essential reason for difference in plant water use strategy is groundwater depth,if groundwater level is deep(within 7 m),P.euphratica suffers from serious drought stress,and the hydraulic lift capacity of P.euphratica roots is also strong.The ecology in the lower reaches of the Heihe River has been balanced at the maintenance and development stages,while the desert riparian forest plants in the lower reaches of the Tarim River are still in severe drought stress. References | Related Articles | Metrics

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Functional Traits and Interrelations of Dominant Plant Species on Typical Grassland in the Horqin Sandy Land,China ZHANG Jing, ZUO Xiao-an, LV Peng, YUE Xi-yuan, ZHANG Jing 2018, 35 (1):  137-143.  doi: 10.13866/j.azr.2018.01.17 Abstract ( 1115 )   PDF (1501KB) ( 698 )   In this study,five functional traits including the height,specific leaf area (SLA),leaf dry matter content (LDMC),leaf carbon content (LNC) and leaf nitrogen content (LNN) of 19 dominant plant species on the Horqin sandy land under enclosure were measured.The functional traits differed in two life forms (annual/biennial plants and perennial plants) and two photosynthetic pathways (C3 plants and C4 plants).The discrepancies in functional traits between different life forms and photosynthetic pathways were compared and analyzed.Furthermore,the interrelations of functional traits and the adaptabilities of the plant species to the environment in the typical grassland were discussed.The results showed that the LDMC of perennial plants was significantly higher than that of annual/biennial plants.Regarding to the perennial plants,the height of C3 plants was significantly higher than that of the C4 plants.For the annual/biennial plants,the LNC of C3 plants was significantly higher than that of the C4 plants.Relative to the C4 plants,the LDMC and LNC of the perennial plants were significantly higher than those of the annual/biennial plants.Correlation analyses showed that there was an extremely significant negative correlation between SLA and LDMC,but an extremely significant positive one between LNC and LNN.Based on the results above,following conclusions were obtained: there were the obvious discrepancies in the plant functional traits between the different life forms and the different photosynthetic pathways in the enclosure grassland ecosystem.The adaptability of perennial C4 plants to drought environment was strong. References | Related Articles | Metrics

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Effects of Competition on Tree Height Growth of Sand-fixation Plantations of Pinus sylvestris var.mongolica in Northwest Liaoning Province LEI Ze-yong, ZHOU Yan-ping, ZHAO Guo-jun, ZHANG Yan-song, YU De-liang 2018, 35 (1):  144-149.  doi: 10.13866/j.azr.2018.01.18 Abstract ( 2 )   PDF (773KB) ( 0 )   In forest,competition intensity can be expressed with the total basal area of breast-height or the number of trees per hectare as the degree of crowding neighboring trees.Competition plays a very important role in forest composition,structure and function,it influences the individual survival,population dynamics and physiological process of forest directly or indirectly.In this study,the goal was to determine a reasonable range of competition among individuals for the forest management and the research objective.The Pinus sylvestris var.mongolica plantations planted on sandy land in the Zhanggutai area,Liaoning Province were focused on,where the average annual precipitation was 518.24 mm during the period of 2005-2015.Four sample plots with different stand density were separately selected from the young P.sylvestris var.mongolica plantations (10 a) and the mature ones (40 a),the densities in A1,A2,A3 and A4 were 975,1 175,1 425 and 1 625 plants per hectare in the young forest,and those in B1,B2,B3 and B4 were 350,750,1 200 and 2 975 plants per hectare in the mature forest,respectively.The effects of competition on tree height growth of P.sylvestris var.mongolica plantations on sandy land were assessed with the methods of normality test and variance analysis.The results showed that the tree height of individuals met the normal distribution (α≤0.05) in young P.sylvestris var.mongolica plantations (10 a) and mature ones (40 a) on sandy land,meanwhile,the tree height of individuals met the normal distribution (α≤0.05) in eight different stand density sample plots.The distribution curves of individual tree height of all 10 a stand age sample plots were left skewed,the coefficient of skewness (g1) was in an order of A1<A4<A3<A2<0,and the kurtosis coefficient (g2) was in an order of A4<A2<A3<A1<0.Both the individual tree height and average tree height reached the maximums in competition of 1 425 plants per hectare.Moreover,there were significant differences between competition 1 175 plants per hectare and competition 975 plants per hectare but not in competition 1 625 plants per hectare (P≤0.05).The value of the skewness (g1) kept an order of B1<B2<B3<0<B4,and the kurtosis coefficient (g2) was in an order of B3<B4<B2<0<B1 in stand density. References | Related Articles | Metrics

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Impact of Future Climate Change on Distribution Pattern of Tamarix taklamakanensis and Its Conservation Revelation SU Zhi-hao, PAN Bo-rong, ZHUO Li, LI Wen-jun, LIU Hui-liang, JIANG Xiao-long, YAN De-min 2018, 35 (1):  150-155.  doi: 10.13866/j.azr.2018.01.19 Abstract ( 2 )   PDF (892KB) ( 0 )   In order to predict the impact of future climate change on the potential suitable distribution of Tamarix taklamakanensis,a rare endemic plant species in China,the climate situations in the past (1961-1990),2050 and 2070 were selected to simulate the dynamic change of the distribution of T. taklamakanensis in the Kumtag Desert using the Maxent model. The research results are as follows:① The suitable distribution areas of T. taklamakanensis would be the Tarim Basin,Turpan Basin,Kumtag Desert,and northwest region of the Alxa Desert in Inner Mongolia,and the most suitable potential distribution area would be the Kumtag Deser in the hinterland and the eastern part of the Tarim Basin;② Compared with the past potential distribution of T. taklamakanensis, the most suitable potential distribution areas would be shrunk in both 2050 and 2070;③ The climatic factors affecting the potential distribution of T. taklamakanensis would be mainly the precipitation in the driest season,annual precipitation,annual temperature and precipitation in the warmest season. References | Related Articles | Metrics

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Age Composition and Dynamic Characteristics of the Main Populations of Endangered Malus sieversii MA Chuang, YANG Mei-ling, ZHANG Yun-xiu, YAN Guo-rong, XU Zheng 2018, 35 (1):  156-164.  doi: 10.13866/j.azr.2018.01.20 Abstract ( 3 )   PDF (1268KB) ( 0 )   Malus sieversii is a precious and endangered species in China. In this study,the sample plots of M. sieversii were delimited at the typical sites including Nazi (NZ),Mohuer (MH),Narat (NRT) and Jiaotuohai (JTH) in the Ili River Valley so as to investigate the age composition and population status of M. sieversii,make the static life table,and carry out the survival analysis.The time series analysis was used to predict the population trend.The study results could provide the theoretical information for protecting M.sieversii .The results showed that the proportion of young trees was low,and that of middle-aged and old trees was high.The average age in NZ was older,and that in JTH was younger.Compared with others,the population in MH was more sensitive to environment disturbance.The number of survivors,total individual number and life expectation of the population were lower in NRT than in other places.The population in NRT decreased early with high elimination rate.The survival curve appeared to approach the Deevey-Ⅱ type,which indicated that the mortality rate of the trees with different ages was similar.With the age increase,the mortality density curve decreased firstly and then increased.The hazard rate increased obviously after age class Ⅳ,which indicated that the effect of environment pressure on M.sieversii was significant after age class Ⅳ.Because of the disturbance from grazing,tourist activities and insect pests,it was predicted with the time series analysis that the proportion of old trees increased with the decrease of the proportion of young and middle-aged individuals.It was suggested that the protection of M.sieversii resources should be strengthened by a series of measures,such as artificially increasing the number of seedlings,regulating the forest density,strictly preventing and controlling plant diseases and insect pests,and protecting the core areas to relieve the contradiction between forestry and grazing. References | Related Articles | Metrics

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Effect of Death Individual on the Genetic Diversity of Malus sieversii Population LI Yu-xiu, ZHANG Hong-xiang 2018, 35 (1):  165-170.  doi: 10.13866/j.azr.2018.01.21 Abstract ( 2 )   PDF (1019KB) ( 0 )   Malus sieversii is one of the national second-class protective plants and an important wild fruit germplasm resources.In this study, the M.sieversii population in Xinyuan County, Xinjiang was selected to research the genetic difference between the death and alive individuals of M.sieversii suffering from the serious diseases and insect pests than other populations, the effect of death individuals on the genetic diversity of M.sieversii was evaluated, and the genotypes of death and alive individuals were marked using the microsatellite markers.The results are as follows: ① There was no significant genetic divergence between the death and alive individuals, which indicated that the death of M.sieversii was random and out of genetic correlation;② Genetic structure of M.sieversii population in Xinyuan was not significantly influenced by tree death.The level of genetic diversity decreased slightly after the tree death, but a lot of low frequency alleles were lost;③ During the future monitoring and evaluation of the change of M.sieversii genetic resources, the number of alleles (Na) was more suitable for effectively reflecting the variation of genetic resources than the indexes of genetic diversity. References | Related Articles | Metrics

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Spatiotemporal Variation of NDVI in the Middle Reaches of the Tarim River Based on GIS Buffer Function LIU Jiao, HUANG Xian-feng, FANG Guo-hua, CHEN Ying-qing 2018, 35 (1):  171-180.  doi: 10.13866/j.azr.2018.01.22 Abstract ( 3 )   PDF (4018KB) ( 0 )   Hydrological conditions affect the development of riparian ecosystems in sensitive watershed.The water-conveyance embankment project constrains overflow in the middle reaches of the Tarim River in flood season and improves the water conveyance efficiency downstream.However,the project also brings about some ecological problems.In this paper,the natural vegetation along the middle reaches of the Tarim River was regarded as the research object,and the changes of normalized differential vegetation index (NDVI) and land use in 2000 (before the project) and 2010 and 2014 (after the project) were comparatively analyzed using the remote sensing and GIS means.The results showed that the NDVI of natural vegetation decreased with the increase of the distance away from the embankment.The NDVI value in a 2 km wide zone away from the embankment in 2000 was holistically higher than that in 2010 except that in a 600-800 m wide zone; in a 20 km wide zone away from the embankment,the NDVI value around a 10 km wide zone in 2000 was higher than that in 2010,on the contrary,it in a zone further than 10 km away from the embankment in 2010 was higher than that in 2000 due to the increase of human activities and the decrease of the effect of natural factors on vegetation.Viewing from the land use change,the area of cultivated land in the study area in 2014 was about 9 times of that in 2000,the vegetation area was reduced by 11.22%,and some natural forest land was transformed into farmland. References | Related Articles | Metrics

Plant Physiology

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Morphological Characters of Peristome and Spore of Bryum Hedw. (Bryaceae) from the Altun Mountain National Nature Reserve in Xinjiang Mamtimin Sulayman, Atigul Molla, Gulnigar Aysirahun, LIU Yong-ying 2018, 35 (1):  181-191.  doi: 10.13866/j.azr.2018.01.23 Abstract ( 2 )   PDF (3624KB) ( 0 )   The paper aimed to figure out the taxonomic values of the peristomial structure and spore morphology in Bryum,and also to discuss the relationship between the natural environmental conditions and the diversity of Bryum at the Altun Mountain National Nature Reserve in Xinjiang. Morphological characters of peristome and spores from 18 species of the genus Bryum in the area were observed by the scanning electronic microscope (SEM).The results showed that: ① The characters,such as the exostomium teeth shape,pattern of exostomium dorsal surface,width of perforation on the endostomium segments,length of the endostomum basal membrane,development of cilia and exine ornamentation of spore,were different among the taxa in Bryum,and they were stable for each species in the genus.So their presence is often considered to be highly diagnostic and taxonomical in infrageneric classification combining with other sporophyte characteristics and/or gametophyte characteristics;② When the peristome developed most highly (the so-called perfect peristome),it was consisted of the longer exostome teeth,a high endostomium basal membrane,broad segments and appendiculate cilia.Otherwise,less intricate peristomes (the so-called simpler peristome) of some Bryum species had shorter exostome teeth,lower endostomium basal membrane,narrower segments and shorter and fewer cilia or absent;③ It seems that the rich diversity of Bryum in the Altun Mountain National Nature Reserve is related to the peristomium structure and spore morphology being adaptive for spore dispersing in dry environment. References | Related Articles | Metrics

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Response of C,N and P Stoichiometry of Chenopodium quinoa to Phenological Phase in the Hexi Corridor LIU Min-guo, WANG Shi-jia, LU Jiao-yun, YANG Mei, YANG Hui-min 2018, 35 (1):  192-198.  doi: 10.13866/j.azr.2018.01.24 Abstract ( 2 )   PDF (997KB) ( 0 )   Chenopodium quinoa is a traditional crop in South America with its high nutritional value and strong environmental adaptability,while its adaptability in arid area of northwest China needs to be further studied.Ecological stoichiometry is the study of the elemental composition of organisms (mainly C,N,P) and their relationships,and it can be used to reflect the characteristics of organisms and their relationship with environment.The changes of contents of carbon (C),nitrogen (N) and phosphorus (P) and stoichiometric ratio at different phonological phases of C.quinoa were studied in a field trial in the Hexi Corridor.The organic carbon (OC) content hardly changed with the change of phenological phases,while the contents of total nitrogen (TN) and total phosphorus (TP) decreased significantly.There was no difference of OC content among organs,while the contents of TN and TP were significantly different with higher values in leaves and spikes.The C∶N and C∶P tended to increase with the plant growth,while N∶P decreased at first and then increased significantly.The C∶N and C∶P in roots and stems were higher than those in leaves and spikes,while N∶P in leaves was higher.The contents and stoichiometric ratios of C,N and P of C.quinoa were significantly affected by phenological phases and organs,showing the very close links with the growth and accumulation rate of dry matter. References | Related Articles | Metrics

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Principal Components and Cluster Analysis on the Physiological and Biochemical Indexes of Introduced Plants in Lop Nur GAO Jie, LI Cong-juan, XU Xin-wen, SUN Yong-qiang 2018, 35 (1):  199-206.  doi: 10.13866/j.azr.2018.01.25 Abstract ( 3 )   PDF (1255KB) ( 0 )   Lop Nor is a desert area in the eastern part of the Taklimakan Desert in Xinjiang,China.It is extremely arid and there are scarcely any plants in this region.In 2013,Xinjiang Institute of Ecology and Geography,the Chinese Academy of Sciences,established a 1.3 hm2.artificial ecological demonstration zone and introduced more than 70 plant species.Because of the extremely harsh natural conditions,fewer than 30 species have been introduced so far.In the process of growth and development,plants will be subject to a variety of abiotic factors.Water and temperature are the main factors affecting plant growth.Under the conditions of high temperature and water shortage,the plants adjust their physiological and biochemical processes to adapt the changes of temperature and moisture.In addition,the plants form a certain high temperature resistance and drought resistance mechanism.In order to study the drought resistance and high temperature resistance capability of different species,the high resistance species groups suitable for the severe environment and ensure the introduction of artificial vegetation to Lop Nor,the correlation,principal component and cluster methods were used to analyze the physiological and biochemistry indicators of 20 main introduced plant species in the artificial ecological demonstration garden in the Lop Nur area.The results are as follows: ① There was an extremely significant correlation between photosynthetic pigment and free proline content in leaves,both of them were at a high level under normal irrigation system; ② The indexes of plants were measured by four principal components,they were the photosynthetic capacity,enzyme activity of plant leaves,drought tolerance and organic solvent content in plant leaves.The principal component factor score and ranking showed that Elaeagnus angustifolia L.,Atriplex patens Iljin.and Sphaerophysa salsula DC.were the top 3,which revealed that the growth status of the three species was the best; ③ When the Euclidean distance was 7,the plants were divided into four categories by cluster analysis: (Ⅰ) General growth plants,including Apocynum venetum L.,Calligonum mongolicum Turcz.and other plants,accounting for 80% of the total samples,the high sugar content in leaves of these plants was the main physiological characteristic; (Ⅱ) Good growth plant,Lycium barabrum L.,the high photosynthetic pigment content high soluble protein and high free proline content in leaves were the main physiological characteristics; (Ⅲ) Dominant plants,Atriplex patens Iljin.and Sphaerophysa salsula DC.,the high photosynthetic pigment content but the low soluble sugar and free proline content in leaves of these plants were the main physiological characteristics; (Ⅳ) Best growth plant,Elaeagnus angustifolia L.,the extremely high Chla/b value in leaves but low one in other organic solvents were the main physiological characteristics .The results also showed that the physiological mechanism of introduced plants in the severe environment varied greatly.How do these dominant plants adapt the severe environmental conditions in their morphology and organization structure? How does the physiology of the plant change in such severe environment? What are the most significant factors for environmental stress change? What are the causes of this difference in the climate mechanisms of different plants adapting to drought? These issues should be carefully analyzed for future study. References | Related Articles | Metrics

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Ecological Stoichiometric Differences of Nine Typical Eremophyte Species LIU Pei, MA Hui, ZHI Ying-biao, CUI Yan, SUN An-an, GUO Yang-nan, LI Qiang, GAO Tian-yun, ZHANG He-liang, LIU Hai-ying 2018, 35 (1):  207-216.  doi: 10.13866/j.azr.2018.01.26 Abstract ( 2 )   PDF (2435KB) ( 0 )   Chemometrics is normally utilized for studying the energy balance and mass balance in ecological process.It can be used to quantify the relationship between C,N and P in living organisms.In recent years,some studies indicate that the introduction of chemometrics avails the solution of various scientific issues associated with the nutrient demand and supply of plants and ecosystems.In other words,chemometrics provides a novel methodology for addressing issues in terms of nutrient demand,supply and cycle of ecosystem.Chemometrics has become as one of the major methods in studying the balance of chemical elements of ecosystem and the biogeochemical cycle.In order to elucidate the adaptation ability in adversity of eremophytes and clarify how chemical element cycle under extreme environmental conditions,this paper carried out a research on nine dominant eremophytes in desert ecosystem in the east Alxa-west Erdos,including Sarcozygium xanthoxylon,Populus euphratica,Tetraena mongolica,Nitraria tangutorum,Amygdalus mongolica,Ammopiptanthus mongolicus,Calligonum arborescens,Hedysarum scoparium and Hippophae rhamnoides,to figure out the contents of C,N and P in their roots,stems and leaves,and to analyze the characteristics of ecological stoichiometry.The results are as follows: ① The average contents of C,N and P in roots,stems and leaves of the nine eremophytes were 418.96 mg·g-1,15.07 mg·g-1 and 1.10 mg·g-1; 460.88 mg·g-1,12.99 mg·g-1 and 1.03 mg·g-1;and 435.07 mg·g-1, 23.40 mg·g-1 and 1.18 mg·g-1,respectively.The stoichimetric ratios of C∶N∶P were 381∶14∶1, 447∶13∶1 and 369∶20∶1 respectively.These figures showed that the amount of C in these nine eremophytes was excessive,but that of P was limited; ② The reserve capacity of C in roots of eremophytes was low due to the infertile soil,strong sunshine and low annual precipitation in the desert ecosystem; ③ The average stoichimetric ratio of N∶P of global terrestrial plants is 12.6,of that in China is 16.3,and of plants in typical desert and desertification areas in north China is 15.8.Compared with them,the stoichimetric ratio of N∶P of T.mongolica was significantly lower and only 9.45.This result showed the peculiarity of chemometrics of T.mongolica, and it is one of endemic and rare plants in China; ④ Compared with the available results of the studies on chemometrics of eremophytes,the contents of N in roots,stems,and leaves of these nine eremophytes were significantly higher,and the contents of P in stems and leaves were significantly lower.There was no remarkable difference in the content of P in roots.The long-term biological and environmental co-evolution allows eremophytes to establish their unique stoichiometric characteristics under specific environmental stress,such as extreme temperature,drought,nutrient limitation and radiation damage.The results of this study provide a reference for analyzing the cycle of chemical elements in eremophytes growing in desertification areas in northwest China,and also provide a case for determining the limit nutrient at the respect of conservation of biological diversity. References | Related Articles | Metrics

Ecologyand Environment

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Changes of Land Use and Landscape Pattern in the Guanzhong Area in Recent 25 Years DU Jin-long, ZHU Ji-wei, XIE Jian-cang, MA Zeng-hui 2018, 35 (1):  217-226.  doi: 10.13866/j.azr.2018.01.27 Abstract ( 2 )   PDF (1568KB) ( 0 )   The Guanzhong area in Shaanxi Province is the core area of Guanzhong-Tianshui Economic Zone.It is an important part of the national “seven zones and twenty-three zones” agricultural development strategy and a new starting point for the economic belt of the Silk Road that is currently in the full construction at the same time.Influenced by the natural environment and human activities,the land use and landscape pattern in the study area were changed obviously in recent 25 years.Based on the four periods of 30 m grid land use data of Shaanxi Province during the period from 1990 to 2015,the temporal and spatial variation characteristics and driving forces of land use and landscape pattern in the study area in recent 25 years were analyzed by using GIS technology and landscape ecological methods.There were six types of land use in the study area,and the results showed that the main land use types were cultivated land,forestland and grassland.The area of cultivated land was the largest and accounted for 46.25%,45.81%,44.73% and 43.94% in 1990,2000,2010 and 2015,respectively.During the study period,the areas of cultivated land and grassland were continuously shrunk,especially the area of cultivated land was sharply shrunk by 12.79×104 hm2.The areas of forestland,waters,urban construction and rural housing land were holistically in an enlarging trend.The area of urban construction and rural housing land was enlarged by 14.94×104 hm2.with an enlargement of 69.88%.The area of unused land was shrunk by 0.58×104 hm2.with a reduction of 38.16%.Because of the intervention of human activities,the mutual conversion among land use types was frequent in the study area.The cultivated land was changed into urban construction and rural housing land,grassland and forestland.The whereabouts and sources of grassland were mainly cultivated land and forestland,and the whereabouts and sources of forestland were mainly cultivated land and grassland.The landscape pattern index highly condenses the information of landscape pattern,which can be used to quantitatively reflect the characteristics of its structural composition,spatial configuration and dynamic change.There are many indexes describing landscape pattern,and some indexes have strong correlation.After fully understanding the ecological significance represented by each index and the emphasis of the landscape pattern reflected by it,a set of reasonable and widely used landscape pattern indices was selected.The landscape shape index was increased from 204.693 4 to 211.805 5,the landscape diversity index was increased from 1.774 6 to 1.851 8,and the landscape evenness index was increased from 0.574 1 to 0.599 1,these indicated that the landscape fragmentation and the landscape heterogeneity were increased during the period from 1990 to 2015.The change of land use and landscape pattern reflected the interaction between human activities and natural factors,and the main driving forces were different from different regions.Landscape pattern change and driving forces have temporal and spatial dynamic relationship.Principal component analysis was used to analyze the ten selected indexes by SPSS 22.0 in this study.The result showed that the driving factors of land use and landscape pattern change in the study area were the socio-economic development,regional policies and agricultural production. References | Related Articles | Metrics

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Spatiotemporal Evolution and Their Formation Mechanism of Settlements in Pastoral Area:A Case Study in Zhenglan Banner ZHANG Su-li, TONG Bao-quan, HAO Jing-jing 2018, 35 (1):  227-234.  doi: 10.13866/j.azr.2018.01.28 Abstract ( 2 )   PDF (2417KB) ( 0 )   As one kind of the important carriers and of the spatial distribution types of the man-land interaction in pastoral area,the spatiotemporal characteristics of settlements can be used to characterize the evolution law of pastoral areas and human settlements.In this study,the statistical analysis methods of GIS and Excel were used to study the spatiotemporal distribution of pastoral settlements in the typical grassland in Zhenglan Banner during the period from 2000 to 2017,and the main factors affecting the settlement formation and development were analyzed.The conclusions are as follows: ① Spatiotemporal distribution of the settlements in Zhenglan Banner was in a rapid growth trend,the overall distribution of settlements was centralized,and the settlement density was high in the south but low in the north; the scale of settlement patches was quite different,and the small settlements were dominant; ② In the region,there was an obvious regional difference in distribution pattern of settlements.Settlements were mainly distributed in the regions with slope of 5°-15°and elevation of 1 196-1 428 m a.s.l.With the change of elevation and slope,the number and scale of settlement patches tended to be a normal distribution,and the number and the scale of settlement patches tended to a gradual decrease with the change of roads and rivers; ③ Hydrology,traffic,topography and other geographical factors limited the location choice of settlements in Zhenglan Banner,and these factors were dominant in spatial distribution of the settlements.In general,the analyzed results of development and formation mechanism of the settlements in pastoral area could provide the important references for regulating and optimizing the spatial layout of the whole pastoral area. References | Related Articles | Metrics

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LUCC-Based Human Disturbance and Ecological Security in Arid Area: A Case Study in the Economic Zone on Northern Slope of the Tianshan Mountains SONG Wen-jie, ZHANG Qing, LIU Sha-sha, YANG Jiang-ning 2018, 35 (1):  235-242.  doi: 10.13866/j.azr.2018.01.29 Abstract ( 2 )   PDF (1410KB) ( 0 )   Ecological security is closely related to the people’s survival and development.In the context of global warming,the ecological and environmental problems have become increasingly prominent with the frequent human activities.Oases in arid areas are the regions with vulnerable environment and economy.Study on ecological security of oases in arid areas is of great significance to the economic stability and development of oases.Based on the land use/cover data in 1965,1980,1995,2005 and 2015,the study analyzed the temporal and spatial changes in human disturbance and ecological security of oases in the economic zone on northern slope of the Tianshan Mountains in recent 50 years by establishing the ecological security index through human disturbance index and landscape vulnerability index.The results showed that the human disturbance in the study area in recent 50 years was increased year by year and reached to a moderate-strong degree in 2015.The human disturbance degree in Urumqi,Shihezi,Kuytun,Miquan and Changji was higher than that in other regions.The ecological security in the economic zone on northern slope of the Tianshan Mountains tended an increase firstly and then a decrease in recent 50 years.The unsafe level and critical level were dominant in the economic zone on northern slope of the Tianshan Mountains,and the regions with these levels were increased and shifted northwestward.The ecological security level was low in Karamay,Shawan and Manas County.Urban construction,oasis expansion and excessive land reclamation were the main factors in reducing ecological security.Structure,human activities and policy were the driving factors of ecological security change in the study area.Structural and policy factors affected the large-scale pattern of ecological security,and human factors affected the small-scale one,On the whole,the ecological environment in the economic zone on northern slope of the Tianshan Mountains is currently still in a high hidden danger,and it is necessary to make reasonable use of land resources in the future development so as to ensure a sustainable development of the study area. References | Related Articles | Metrics

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Complexation of As (Ⅲ) with Extracellular Polymeric Substance from Biofilm in the Salt-discharging Channel in Kuytun,Xinjiang LIN Qing-hua, ZHANG Dao-yong 2018, 35 (1):  243-248.  doi: 10.13866/j.azr.2018.01.30 Abstract ( 2 )   PDF (1448KB) ( 0 )   There is a heavy arsenic pollution in the salt-discharging channel due to the geological background in Kuytun,Xinjiang. The complexation between extracellular polymeric substance of the algal biofilm and As (Ⅲ) influences the transportation and diffusion of arsenic and further affects the biological toxicity and the ecological risk of arsenic.At present,the effects of the widespread biofilm on the transport and fate of arsenic in channel are completely unknown.In this study,the interaction of extracellular polymeric substance of the algal biofilm and As (Ⅲ) was investigated by fluorescence quenching test and isothermal titration calorimetry.The results of fluorescence quenching test showed that the fluorescent components of extracellular polymeric substance were composed of three fluorescence peaks: Peak A belonged to aromatic protein Ⅱ,Peak B belonged to soluble microbial by-product-like,and Peak C belonged to humic acid-like.Peak A and B were collectively referred to protein-like substance,and peak B was further intended to be tryptophan-like substance.There was a strong complexation between the protein-like substance and As (Ⅲ),while the interaction between As (Ⅲ) and the humic-like substance was ignorable.Both static quenching and dynamic collision were involved in fluorescence quenching of extracellular polymeric substance by As (Ⅲ).The binding constant,lgKb,for interaction of As (Ⅲ) with the aromatic protein-like substance and tryptophan-like substance were 3.82 and 2.22 respectively,indicating the binding affinity of As (Ⅲ) to the former is one order of magnitude greater than the latter.Multiple sites were involved in competition for binding As (Ⅲ) in the aromatic protein-like substance,and only one class of binding sites were taken part in tryptophan-like substance for their complexation with As (Ⅲ).The data obtained from isothermal titration calorimetry test were fitted by independent model,and the thermal dynamic parameters ΔH,ΔG and ΔS of complexation reaction were acquired.Negative enthalpy change ΔH and negative Gibbs free energy ΔG proved that the complexation between extracellular polymeric substance and the As (Ⅲ) is a spontaneous exothermic reaction.The degree of disorder in the complexing reaction increases,and the reaction is driven by entropy.The protein-like substance in the biofilm in salt-discharging channel may have significant effects on environmental fate and risk of arsenic,while the role of humic acid-like substance in extracellular polymeric substance is ignorable. References | Related Articles | Metrics