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15 September 2020, Volume 37 Issue 5 Previous Issue    Next Issue

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Dynamic variation and evaporation of seasonal lakes in arid areas:A case study for the Aiding Lake CAO Guo-liang, LI Tian-chen, LU Chui-yu, XU Zhi-xia 2020, 37 (5):  1095-1104.  doi: 10.13866/j.azr.2020.05.01 Abstract ( 1456 )   PDF (5315KB) ( 709 )   Lakes in arid areas are very sensitive to climate change and human activities, and lake area variations are controlled by changes and balance in the water cycle. Taking the Aiding Lake in Turpan, Xinjiang, as an example, this paper used Landsat remote sensing images and the water index method to interpret the lake area of 1986-2018. The relationships between lake area and regional climate change and river runoff changes were analyzed. The inter annual variations of lake water storage and lake evaporation throughout the years were also evaluated. The results show that the maximum surface area of the Aiding Lake generally occurs in March, and the inter annual variations of the largest area of the lake are basically consistent with changes in river runoff into the lake. The maximum lake volume calculated during 1996-2006 was significantly larger than the evaporation capacity of the lake. After 2006, the lake area decreased with the decline in runoff rates. River runoff affected by glacier shrinkage due to temperature change in arid regions is the decisive factor affecting changes in lake area in the wake of rivers in arid regions. References | Related Articles | Metrics

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Study of evapotranspiration estimation and drought characteristics of watershed in low coteau area of Hexi inland river CHENG Wen-ju, XI Hai-yang, SI Jian-hua, LI Ai-lin 2020, 37 (5):  1105-1115.  doi: 10.13866/j.azr.2020.05.02 Abstract ( 446 )   PDF (3256KB) ( 468 )   In order to reveal the evapotranspiration and drought characteristics of typical small watershed in low coteau area of Hexi inland river in the arid regions of northwest China, the Xitugou watershed in Dunhuang is used as an example to calculate the potential evapotranspiration of eight observation sites by Penman-Monteith formula based on the conventional meteorological data. On this basis, the actual evapotranspiration of each observation station was calculated by using the method of dual crop coefficient, which was based on NDVI, and then the standardized precipitation evapotranspiration index SPEI of the watershed was calculated. The results show that the annual potential evapotranspiration and actual evapotranspiration are 978 mm and 258 mm, respectively. From the upper reaches to the lower reaches, with the decrease of altitude, the evapotranspiration shows a different degree of increase; the duration of drought in the lower reaches of the basin is long, and the whole growth season will have different degrees of drought, autumn is the main season of drought; the precipitation in the upper reaches of the watershed is greater than the actual evapotranspiration, the actual evapotranspiration of middle and lower reaches is greater than precipitation; the Kc value of the crop coefficient calculated by the NDVI has good applicability in the estimation of actual evapotranspiration, and the drought index SPEI is more advantageous than SPI and PDSI in the drought assessment in the arid inland river basin of northwest in China. This study calculated the potential and actual evapotranspiration of the Xitugou watershed, evaluated the monthly and seasonal drought characteristics of the watershed, and provided guidance for the production and living water consumption of the watershed, especially in the middle and lower reaches. This research obtained the general disciplines to no data river in the low coteau area of the whole Hexi inland river. References | Related Articles | Metrics

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Study on CO2, CH4, and N2O emissions from reed wetlands in typical freshwater lake and saltwater lake in Xinjiang WANG Shun-ke, LI Yan-hong, LI Fa-dong, WANG Jin-long 2020, 37 (5):  1183-1193.  doi: 10.13866/j.azr.2020.05.11 Abstract ( 641 )   PDF (2492KB) ( 475 )   We compare and analyze the monitoring data of Bosten Lake, China’s largest inland freshwater lake, and Ebinur, Xinjiang’s largest saltwater lake, from December 2016 to November 2017, using static chamber gas chromatography, researching the difference of soil greenhouse gas emissions between typical freshwater lake and saltwater lake reed wetlands in Xinjiang. It showed that (1) by analyzing the average daily emissions during the observation period, it is found that the CO2 emission trend of the freshwater lake shows a single peak curve, and the CH4 emission trends at the adjacent time points are not prominent. The N2O of freshwater lake and saltwater lake are between 9 o’clock and 13 o’clock, and the differences in emissions between 17:00 and 21:00 were not obvious. (2) The seasonal changes of soil CO2, CH4, and N2O in the freshwater lake and saltwater lake reed wetlands showed a single peak curve trend. The peak of greenhouse gas emissions was mainly concentrated in summer. The peak of saltwater lake N2O emissions appeared in autumn. There were no significant differences in CO2 and N2O emissions between the freshwater lake and the saltwater lake (P>0.05), The difference of CH4 emissions between the two lakes is significant (P<0.05). (3) Lake wetlands store large amounts of greenhouse gases in winter. The release of CO2, CH4, and N2O from Bosten Lake in the spring melt accounts for 22%, 30%, and 12% of the total cumulative emissions for the year, and Lake Ebinur accounted for 40%, 0.8%, and 47%. (4) The effects of soil temperature, soil moisture content, and soil organic matter on the CO2 emissions of the saltwater lake were weak. pH inhibited N2O emissions from Bosten Lake, and soil salinity had a strong inhibitory effect on CO2 and CH4 emissions from Ebinur. (5) The global warming potential of lake reed wetland soil in arid areas was as follows: freshwater lake > saltwater lake. Both the freshwater lake and the saltwater lake reed wetlands contribute to global warming on the centennial scale. References | Related Articles | Metrics

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Changes in the mass balance of Arctic Alpine glacier and its response to climate change WANG Pan-pan, LI Zhong-qin, WANG Pu-yu, HE Hai-di, LIANG Peng-bin, MU Jian-xin 2020, 37 (5):  1205-1214.  doi: 10.13866/j.azr.2020.05.13 Abstract ( 643 )   PDF (3515KB) ( 215 )   As an indicator of climate change, glacier mass balance is used to evaluate the contribution of glaciers to runoff and sea-level rise. The monitoring of glacier mass balance has been going on for more than 70 years. On the basis of the data of mass balance, equilibrium- line altitude, and accumulation area ratio published by the world glacier monitoring service (World Glacier Monitoring Service, WGMS), we choose 23 glaciers with long- term observation in the Arctic as the research objects to analyze the mass balance of glaciers and the relationship between mass balance and equilibrium-line altitude and accumulation area ratio. We found that the average thickness of Arctic glaciers decreased by 14.8 m during 1960-2017, with the smallest decrease in Russia, 4.3 m, and the largest in Alaska, 27.7 m; of the 23 glaciers, only the average mass balance of the Engabreen glacier was positive, the Kongsvegen glacier maintained a weak negative balance, and the mass balances of the other 21 glaciers were in a strong negative balance, indicating that the Arctic glaciers were in a strong negative balance. In the past 60 years, the mass balance of glaciers in the Arctic has shown a negative trend. From the late 1990s, glaciers began to melt faster, with a loss rate rising from -128.2 to -594 mm·a-1. The mass balance negatively correlates with equilibrium-line altitude, with a positive correlation with the specific rate of accumulation area ratio. The increase in Arctic temperature is the main reason for the melting of glacial mass balance. The large increase of temperature in the 1990s resulted in the massive loss of glacial mass in the same period, and precipitation has little effect on the mass balance. References | Related Articles | Metrics

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Magnitude of groundwater evapotranspiration in the Badain Jaran Desert based on groundwater dynamics method and empirical model:A case study of the Sumujilin Lake Area ZHANG Wen-jia, WANG Nai-ang, YU Xin-ran, NIN Zhen-min, ZHAO Li-qiang 2020, 37 (5):  1215-1222.  doi: 10.13866/j.azr.2020.05.14 Abstract ( 593 )   PDF (4752KB) ( 316 )   The Sumujilin Lake Area was taken as a study case to determine the contribution of evapotranspiration to groundwater drainage in the Badain Jaran Desert hinterland. Using high- resolution remote sensing image, digital elevation model (DEM), and field- measured groundwater depth, we extracted the ranges of lake water surface, different types of vegetation coverage areas, and groundwater depth hierarchic areas in the study area. Meanwhile, the evapotranspiration of vegetation coverage area and bare land wererespectively calculated on the basis of the groundwater dynamic method and the groundwater evapotranspiration empirical model. The results showed that the evapotranspiration from the Phragmites australis observation area is larger than that from the Nitraria tangutorum- Achnatherum splendens observation area during the same period. There are differences in the evapotranspiration patterns of the two types of observation areas. The former reaches the peak of the evapotranspiration rate during the middle stage of the growing season, whereas the latter reaches the peak during the early stage. Under the same atmospheric conditions, the total amount of groundwater evapotranspiration with vegetation cover in the Sumujilin Lake Area during the growing season is 16% to 18% more than that without vegetation coverage. Therefore, using only bare land groundwater evapotranspiration formulas or models to calculate the groundwater balance of the lake basin would produce large errors. Finally, the total amount of groundwater evapotranspiration in the Sumujilin Lake Area, including vegetation coverage and bare zone with shallow groundwater depth, accounts for 11.3% to 13.2% of the total groundwater drainage in the lake area, which proves that groundwater evapotranspiration is one of the key items of the water cycle of Badain Jaran Desert lakes and could not be negligible in the water balance studies. References | Related Articles | Metrics

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Study on leaf water uptake traits of desert plants in Minqin WANG Fei, GUO Shu-jiang, HAN Fu-gui, WANG Fang-lin, ZHANG Wei-xing, ZHANG Yu-nian 2020, 37 (5):  1256-1263.  doi: 10.13866/j.azr.2020.05.18 Abstract ( 435 )   PDF (3077KB) ( 370 )   Leaf water absorption strategy is of great ecological significance in arid areas, where the water input is dominated by small precipitation and condensate water. In this study, 20 desert plants were taken as the study object in Minqin.We measured LWUC, RW, WSD, SLA, and LDMC and analyzed the distribution characteristics of plant leaf traits and their correlation; the variation characteristics of leaf water uptake traits of small functional groups were compared. The results showed that (1) the leaves could absorb water and could make use of small precipitation. There were significant interspecific differences in leaf traits. (2) LWUC was significantly negatively correlated with LDMC (P<0.01), and RW was positively correlated with WSD (P<0.01). (3) There were no significant differences in LWUC, RW, and WSD of different plant growth forms (P>0.05). (4) There was a significant difference in LWUC among plants with different leaf textures (P<0.01); the succulents had significantly (P<0.05) higher LWUC than the herbaceous and coriaceous plants, and there was no significant difference between the succulents and the aphyllous plants. (5) There was no significant difference in LWUC between plants with different leaf surface traits (P>0.05), but the RW and WSD of tomentose leaves were significantly higher than those of smooth leaves (P<0.01).This study is expected to help better understand the water use manners and strategies of different functional plantsin desert ecosystems and to improve our knowledge of ecological adaption strategies of desert plants and the changes of desert vegetation patterns to provide a scientific basis for their protection and restoration. References | Related Articles | Metrics

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Variation characteristics of canopy nutrients during the rainfall process of Haloxylon ammodendron and Haloxylon persicum in the Gurbantunggut Desert YUE Yue-meng, LI Chen-hua, XU Zhu, TANG Li-song 2020, 37 (5):  1293-1300.  doi: 10.13866/j.azr.2020.05.22 Abstract ( 544 )   PDF (4426KB) ( 219 )   Nutrients are relatively scarce in arid regions, and adequate nutrient input after rainwater flows through the canopy is of great significance to the growth and development of plants in arid regions. Through the study ofcanopy nutrients during the rainfall process of Haloxylon ammodendron and H.persicum, which were the maindominant species in the southern margin of the Gurbantunggut Desert, the concentration differences of carbon,nitrogen, and phosphorus in stemflow, throughfall, and rainwater were analyzed, and the concentration degree ofions after rainwater flows through the plant canopy was determined. The results showed that the total organic carbon (TOC) and total nitrogen (TN) concentrations of rainwater increased significantly after passing through the canopy of Haloxylon ammodendron and Haloxylon persicum, and the total phosphorus (TP) did not increase significantly. Thechange of ammonium nitrogen ( NH4+ -N) concentration is basically consistent with that of TN, and the difference between nitrate-nitrogen ( NO3- -N) and nitrite-nitrogen ( NO2- -N) concentrations is not completely significant. Among them, the trunk organic nitrogen (TON) has the highest proportion, and its proportion in TN is always greater than 50%. For the average concentration of different nutrient inputs, in addition to TP and NO3- -N, other ions have increased. The concentrations of TP, NO3- -N, and NO2- -N are lower, and they flow in the stems of stemflow,through fall, and rain. The coefficient of variation is larger in. References | Related Articles | Metrics

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Ecological security evaluation of an oasis in the north of the Tianshan Mountains based on three-dimensional ecological footprint model LI Peng-hui, XU Li-ping, LIU Xiao, WU Pin-ru 2020, 37 (5):  1337-1345.  doi: 10.13866/j.azr.2020.05.27 Abstract ( 531 )   PDF (5646KB) ( 318 )   We used an improved three-dimensional ecological footprint model to evaluate the ecological security of the northern oasis of the Tianshan Mountains from 2000 to 2016. The results show that (1) from 2000 to 2016, the overall ecological environment of the northern oasis of the Tianshan Mountains is in an unsustainable state of development, and the ecological footprint continues to increase. The ecological footprint has increased from 8.38×106 hm2 to 2.73×107 hm2 with an average growth rate of 1.11×106 hm2·a-1. Ecological security is seriously threatened. (2) After 2002, the relative disparities in the unsustainability of the northern oasis of the Tianshan Mountains gradually decreased, and the relative differences in the ecological deficits of the internal administrative units gradually narrowed. (3) The ecological utilization efficiency of the northern oasis of the Tianshan Mountains as a whole has shown an increasing trend, which has tripled in 17 years. The degree of utilization of resources has become more and more abundant, and the economic value created by unit resources has continuously increased. However, the rate of change in each year has fluctuated dramatically, and the fluctuation range is between -18.23% and 120.84%. (4)Although the ecologically moderate population of the Tianshan Mountains’northern oasis shows a fluctuating growth trend, the demand for and use of resources are also increasing rapidly, and the continuously growing population has caused tremendous pressure on the ecological environment. Finally, some suggestions were put forward to ease the ecological pressure, reduce the ecological deficit, and promote the sustainable development of the northern oasis of the Tianshan Mountains. References | Related Articles | Metrics