Table of Content

15 March 2023, Volume 40 Issue 3 Previous Issue    Next Issue

Weather and Climate

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Variation of mean maximum temperature from March to April since 1923 in the northern section of Lvliang Mountain recorded by tree rings WANG Jiachuan, LI Shuheng, GUO Yili, HAN Yijie, MAO Zhonglei 2023, 40 (3):  337-348.  doi: 10.13866/j.azr.2023.03.01 Abstract ( 352 )   HTML ( 26 )   PDF (9152KB) ( 108 )   With the established standard chronology of the tree-ring width of Larix principis-rupprechtii in the Guancen Mountain in the northern section of Lvliang Mountain as basis, Pearson correlation analysis concluded that the average maximum temperature from March to April was the main controlling climate factor for the radial growth of trees in the study area (R = 0.509, P < 0.05). First-order linear regression equation was used to simulate and construct the change process of the average maximum temperature in the Guancen Mountains from March to April in the past nearly a century. The reconstructed equation was then cross-checked by the elimination method of leave-one-out test to verify its stability and reliability. Analysis of the temperature changes of the reconstructed temperature series showed that two warm periods and three cold periods in the past nearly a century in the Guancen Mountain area; the warm periods were 1932-1945 and 1957-1970, and the cold periods were 1946-1956, 1971-1983, and 1993-2010. Periodic analysis of the reconstructed temperature series based on Morlet wavelet analysis revealed periodic distribution characteristics of 3~5 a, 10~13 a, 22~33 a, and 40~45 a. El Niño-Southern Oscillation and sunspot activity were the drivers of this periodic variation. Large-scale spatial correlation analysis indicated that the reconstructed temperature series had a good spatial representation of temperature changes in large-scale regions such as central and eastern Russia, northern Japan, and central and eastern China. These results have important reference value for forest management and agriculture and animal husbandry development in Guancen Mountain area. Figures and Tables | References | Related Articles | Metrics

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Air quality characteristics and its potential health effects in Hotan City WANG Na, Tayierjiang AISHAN, Yumiti HALIKE, WANG Huijuan, Maierhaba WUMAIER 2023, 40 (3):  349-357.  doi: 10.13866/j.azr.2023.03.02 Abstract ( 495 )   HTML ( 21 )   PDF (9390KB) ( 330 )   The status of air pollution in China has been recognized as a serious health concern in numerous academic circles. Air quality is an important factor for defining air pollution, and main pollutants used to evaluate its quality, include PM2.5, PM10, SO2, NO2, CO, and O3. Hotan is one of the oasis cities with severe air pollution crisis. The located in the southwest edge of Taklimakan Desert in the southernmost part of the Northwest Xinjiang province in China. The soil structure in this area is loose, dust storms are frequent, and particles carried by dust storms are heavily deposited, which result in an increase in the concentration of pollutants. Therefore, the air Pollution caused by these particles results in severe challenges. Different types of air pollutants have varied hazards to human health, for example, PM2.5 and PM10, which are the main air pollutants in Hotan City, cause serious human respiratory tract infections, and their sources are extensive, hazardious, and difficult to eliminate. The rapid economic development in recent years and the accelerated urbanization have aggravated the deterioration of air quality in Hotan City, posing a great threat to the physical and mental health of local residents. Therefore, understanding the characteristics of air quality and its potential health effects in Hotan City is crucial for controlling urban air pollution and improving local ecological environment. This study used the historical air quality data in Hotan from 2016 to 2021 to analyze the distribution characteristics of pollutants, to determine the relationship between air quality and potential human health effects, and to evaluate the correlation between pollution levels and air pollutants, such as PM2.5, PM10, SO2, NO2, CO, O3-8H, and AQI. The results showed that between 2016 and 2021, the concentration of O3-8H in two air pollution monitoring points in Hotan had an inverted U-shaped trend, while the concentration of other pollutants showed a U-shaped curve distribution. PM2.5 and PM10 were detected as the main pollutants throughout the year, and their concentrations were relatively high in spring. In addition, concentrations of SO2 and NO2 were high in autumn and winter, while those of CO and O3-8H were high in winter and summer, respectively. During the study period, the concentration of PM2.5 and SO2 decreased, while that of PM10 increased, but the overall air quality did not show significant improvement. The AQI value of air quality index in Hotan City was higher than the national second class level, and its value during the “unhealthy” air quality period was much higher than that during the “healthy” air quality, which suggested a high harmful potential to the physical and mental health of residents. Figures and Tables | References | Related Articles | Metrics

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Temporal and spatial changes of evapotranspiration in the Shaliu River Basin of Qinghai Lake KANG Ligang, CAO Shengkui, CAO Guangchao, YANG Yufan, YAN Li, WANG Youcai 2023, 40 (3):  358-372.  doi: 10.13866/j.azr.2023.03.03 Abstract ( 377 )   HTML ( 30 )   PDF (16283KB) ( 155 )   Evapotranspiration (ET) is the total flux of water vapor transported by vegetation and the ground as a whole to the atmosphere. As an important part of energy balance and water cycle, ET affects the growth and development of plants and regulates climate by influencing atmospheric circulation. Using MODIS image data combined with digital elevation model data and meteorological data, this work applied ArcGIS spatial analysis and mathematical statistics to study the temporal and spatial characteristics of ET in the Shaliu River Basin of Qinghai Lake in the past 20 years from 2000 to 2019. The correlation between ET and meteorological factors such as air temperature, precipitation, and relative humidity and its topographic effect was also explored. Results show that: (1) the annual average ET in the Shaliu River Basin of Qinghai Lake is between 379.7 and 575.4 mm, and the average ET is 501.9 mm. The overall trend of fluctuation increases significantly with the number of years (P<0.05), and the linear slope is 5.9 mm·a-1. (2) From a spatial perspective, the average ET in the Shaliu River Basin of Qinghai Lake has significant spatial differences and shows a distribution pattern of “high in the middle and low at both ends,” that is, the ET in the source area and the downstream estuary delta area is lower than that in the middle reaches. The order is as follows: alpine meadow belt > alpine cold desert belt > alpine grassland belt. The areas with a relatively significant increase in ET are mainly distributed in the estuary delta area in the lower reaches of the basin, accounting for 9.7% of the basin area. Meanwhile, the areas with a relatively slight increase occupy the main body of the basin, accounting for 81.2%. (3) The annual ET is related to the annual average temperature, and the annual precipitation is significantly positively correlated with the annual average relative humidity. Warming is the fundamental driving force for the increase in ET. (4) The annual ET showed an “increase-decrease-increase” trend with the increase in the slope, but the overall difference between the slopes is not evident. Except for the smallest plane ET in different slope aspects, the differences in annual ET among the other slope aspects are small. The annual ET increases sharply at first and then gradually with the altitude. The above results show that in the past 20 years, the warming and humidification of the climate in the Shaliu River Basin of Qinghai Lake has led to an increase in ET. However, the band increase is small. Figures and Tables | References | Related Articles | Metrics

Land and Water Resources

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Capillary water movement characteristics in loamy sand under different water levels: A case study in the Yarkant River Irrigation Area of Xinjiang Province, China CHEN Yongbao, HU Shunjun, ZHANG Shujie, PEI Mingsong, ZHANG Qiaoli 2023, 40 (3):  373-380.  doi: 10.13866/j.azr.2023.03.04 Abstract ( 296 )   HTML ( 9 )   PDF (4309KB) ( 204 )   River canal leakage is the main mode of surface water replenishment to soil water for desert riverbank ecological protection, plant water absorption, and utilization. It is also an important cause of soil salinization during increased groundwater level periods. Therefore, studying the movement of groundwater and soil moisture under the condition of canal leakage recharge in arid areas can be crucial not only for constructing a benign ecological circulation system dominated by water environment, but also for preventing soil salinization. This study used laboratory simulation experiment to analyze the capillary water movement characteristics in loamy sand under different water levels in Yarkant River irrigation area. Results showed a decreasing trend in the capillary water supply rate, which could be subdivided into three stages, including rapid decrease, linear decrease, and stable-state, while the average stable recharge rate 0.02 mm·min-1 was detected. The rising height of capillary water and rising rate both had parabola relationships with the recharge time. Validation of the linear relationship between capillary water recharge and rising height of capillary water under different canal water levels revealed that the slope (B) was equal to the difference between the mean soil water content (θmean) and initial water content (θi), while B values under different canal water levels ranged from 0.3155 to 0.4046 cm3·cm-3, with a mean value of 0.3695 cm3·cm-3. A linear correlation was detected between capillary water supply rate and the reciprocal value of rising height of capillary water. The improved Green-Ampt model could successfully be used to simulate capillary water rise process in a homogeneous loamy sand. Overall, these results could potentially provide clues for studying the restoration and reconstruction of ecologically protected plants in canals, and for the prevention of soil salinization in arid areas. Figures and Tables | References | Related Articles | Metrics

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Effects of climate and land use change on the spatial distribution of hydrological factors in the source region of Datong River ZHAO Meiliang, CAO Guangchao, ZHAO Qinglin, CAO Shengkui 2023, 40 (3):  381-391.  doi: 10.13866/j.azr.2023.03.05 Abstract ( 298 )   HTML ( 19 )   PDF (10311KB) ( 70 )   Water shortage has become a major resource and environmental challenge worldwide. Climate and land use change have made the evolution of current hydrological factors complex and uncertain. Exploring the spatial distribution characteristics of hydrological factors under dynamic scenarios is of vital theoretical and practical significance for the sustainable development of regional economy and society. The meteorological and hydrological data of the Datong River source region from 1960 to 2019 were used in this study to quantitatively analyze the spatial distribution characteristics of hydrological elements under climate and land use change scenarios based on model simulation and scenario segmentation. The results showed that: (1) After calibration and verification of the SWAT model, the coefficient of determination, Nash coefficient, and percentage bias (PBIAS) all met the model requirements of 0.81%, 0.79%, and -0.8% in the rate period, and 0.81%, 0.75%, and 15.8% in the validation period, respectively, which indicated that the model had good applicability in the headwaters of the Chase River. (2) Obvious spatial heterogeneity of hydrological elements was detected in the headwater area of Datong River, and a single hydrological element could not represent the overall spatial distribution. Precipitation, potential evapotranspiration, and soil water content decreased with the increase in altitude, while surface runoff and water yield increased with the increase in altitude. (3) The spatial distribution of hydrological factors under the three scenarios were generally consistent, while the spatial distribution of water yield was greatly affected by the land use change. Under the climate change scenario, the actual evapotranspiration and soil water content showed a downward trend, while the surface runoff and water yield showed an upward trend. Under the land use change scenario, the changes of hydrological elements were contrary to these observations. Figures and Tables | References | Related Articles | Metrics

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Effect of the salinity of irrigation water on soil respiration rate in cotton field LI Yanqiang, WANG Zhenhua, YE Hanchun, SONG Libing, LIU Jian, WEN Yue, WU Xiaodi 2023, 40 (3):  392-402.  doi: 10.13866/j.azr.2023.03.06 Abstract ( 230 )   HTML ( 9 )   PDF (2654KB) ( 117 )   Four irrigation water salinity levels, namely, 0.85 g·L-1 (CK, local irrigation water salinity), 3 g·L-1 (S1), 5g·L-1 (S2), and 8 g·L-1 (S3), were examined to explore the effects of different salinity levels on soil respiration rate in cotton fields. A cotton field experiment with drip irrigation under film was carried out in Xinjiang. During the growth period of cotton, soil respiration rate (Rs) was recorded twice a month, along with soil temperature (ST), water content, electrical conductivity (EC), nitrate nitrogen content ($\mathrm{NO}_{3}^{-}-\mathrm{N}$) and ammonium nitrogen content ($\mathrm{NH}_{4}^{+}-\mathrm{N}$). The influence of soil parameters on soil respiration rate under different salinities of irrigation water was studied by path analysis. Results showed that brackish water irrigation (S1 and S2) increased soil moisture content, EC and ammonium nitrogen content to a certain extent. Salt water irrigation (S3) significantly increased soil moisture and salinity, and decreased soil nitrate nitrogen content. The increase in the salinity of irrigation water decreased the soil respiration rate. The correlation between soil moisture and temperature and respiration rate decreased with the increase in the salinity of irrigation water. The quadratic function was used to represent the response of ST in 0-10 cm soil layer to soil respiration rate (R2=0.669, P<0.001). The optimal ST for soil respiration rate was 26.9 ℃. Under saline irrigation, the stepped-regression equation containing ST, conductivity, and nitrate nitrogen content could explain 85% of the variation of soil respiration rate. In conclusion, the use of 3 g·L-1 irrigation water for drip irrigation under film can reduce soil respiration rate and farmland carbon emissions without significantly increasing soil salt content. This work provides theoretical support for the development and utilization of brackish water resources in Xinjiang. Figures and Tables | References | Related Articles | Metrics

Plant Ecology

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Morphological characteristics of Nitraria tangutorum nebkhas in Jilantai desert-oasis ecotone WEI Yajuan, DANG Xiaohong, WANG Ji, HAN Yanlong, XIE Yunhu, LIN Bo 2023, 40 (3):  403-411.  doi: 10.13866/j.azr.2023.03.07 Abstract ( 263 )   HTML ( 16 )   PDF (3615KB) ( 79 )   Nitraria tangutorum nebkha is a common natural landscape in the desert-oasis ecotone of Jilantai; however, the growth characteristics of N. tangutorum shrubs and the morphological characteristics of N. tangutorum nebkhas under different background vegetation coverages remain unknown. Through the measurement of shrubs and morphological characteristics of N. tangutorum nebkhas, the variability of morphological parameters of N. tangutorum nebkhas and the relationship between the growth characteristics and morphology of N. tangutorum nebkhas were quantitatively analyzed under different background vegetation coverages. The influence of background vegetation coverage on the succession of N. tangutorum nebkhas was also discussed. Results showed that: (1) the evolution of N. tangutorum nebkhas was stable under four different background vegetation coverages. The morphological parameters of N. tangutorum nebkhas gradually developed toward large scale and small density with the increasing background vegetation coverage. (2) Overall, a good correlation was found between the morphological parameters of N. tangutorum nebkhas under different background vegetation coverages. (3) In the desert-oasis ecotone of Jilantai, the relationship between the L and W of N. tangutorum nebkhas followed a quadratic or power function, and the relationship between the A and V of N. tangutorum nebkhas followed a power function. Except for sample site 1, the relationship between A and H and between H and D followed linear trend and power function, respectively. (4) The coverage of N. tangutorum nebkhas was mainly 40%-80%, accounting for 64.62% of total N. tangutorum nebkhas in the desert-oasis ecotone of Jilantai. This finding indicated that the N. tangutorum nebkhas in the study area is well grown, widely developed, and temporarily not a source of wind and sand damage to the oasis. Figures and Tables | References | Related Articles | Metrics

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Effects of hydraulic traits on the species abundance distribution pattern of desert plant communities SUN Qixing, YANG Xiaodong, LI Borui, KONG Cuicui, Elhamjan ANWAR, ZHOU Jie, LYU Guanghui 2023, 40 (3):  412-424.  doi: 10.13866/j.azr.2023.03.08 Abstract ( 289 )   HTML ( 14 )   PDF (6612KB) ( 132 )   Plant death caused by drought is an important cause of species composition changes in terrestrial ecosystems. Revealing the influence of hydraulic triats on species distribution, which is of great theoretical significance for understanding plant drought adaptation, restoration and management of desert vegetation. In this study, the woody plants in the Ebinur Lake Wetland Nature Reserve were selected as subject to compare the variation characteristics of species abundance and hydraulic traits under soil drought gradient and analyze the relationship between hydraulic traits and species abundance distribution. Results showed that the sum of abundance (community density) of all species did not change significantly. However, the responses of different species abundance to drought stress were significantly different. With the increase in soil drought, the specific conductivity, quasi-steady conductivity, and Huber value increased; the water potential of branches and leaves decreased continuously, and the stem wood density did not change significantly. The difference of hydraulic triats among species changed with the degree of drought. Redundancy analysis and generalized additive model showed that 92.8% of the variation of desert woody plant abundance distribution pattern can be explained by the measured hydraulic triats. In addition, plant abundance increased with the quasi-steady conductivity, specific conductivity, Huber value, and water potential of branches and leaves but decreased with the increase in stem wood density. Therefore, the changes of the woody plant abundance distribution can be predicted using the changes of hydraulic traits. Figures and Tables | References | Related Articles | Metrics

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Variation in the leaf functional traits of typical desert shrubs under precipitation gradient LI Rui, SHAN Lishan, XIE Tingting, MA Li, YANG Jie, LI Quangang 2023, 40 (3):  425-435.  doi: 10.13866/j.azr.2023.03.09 Abstract ( 276 )   HTML ( 16 )   PDF (4595KB) ( 118 )   Natural precipitation is an important source of water for vegetation in arid areas. To explore the coping methods of desert shrubs under different precipitation conditions, this study selected typical desert shrubs as subject and determined their leaf morphological traits and stoichiomental characteristics under different precipitation condition. The overall characteristics of leaf functional traits and the relationship between individual functional properties and environmental factors were also analyzed. Results showed that (1) with the decrease in natural precipitation, the degree of fleshiness and water content of leaves of Reaumuria soongorica increased gradually and the tissue density of Kalidium foliatum increased. (2) Meanwhile, the C contents in the leaves of R. soongorica and Nitraria tangutorum and the N contents in the leaves of N. tangutorum and Salsola passerina showed an overall increasing trend with the increase in drought stress. In addition, the leaf N:P ratios of S. passerina and K. foliatum were all less than 14, indicating that the growth and development of these species were mainly restricted by nitrogen. (3) The leaf tissue density of R. soongorica, N. tangutorum, and K. foliatum was positively correlated with the average annual precipitation. The specific leaf area of R. soongorica and N. tangutorum and the P content of R soongorica, N. tangutorum, and S. passerina were negatively correlated with altitude. In arid environments, different plants exhibit different ecological adaptation strategies. To adapt to the desert environment of drought and less rainfall, K. foliatum reduces its specific leaf area and increases its tissue density, N. tangutorum increases the N content of its leaves, and R. soongorica increases the degree of fleshiness and water content of its leaves. Average annual precipitation and altitude are the main limiting factors affecting their growth and development. Figures and Tables | References | Related Articles | Metrics

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Water source of spruce (Picea schrenkiana) at different altitudes in the Tianshan Mountains during the growing season TIAN Shengchuan, ZHAO Shanchao, ZHENG Xinjun, WANG Yugang, LI Yan 2023, 40 (3):  436-444.  doi: 10.13866/j.azr.2023.03.10 Abstract ( 293 )   HTML ( 13 )   PDF (3261KB) ( 167 )   Picea schrenkiana is a typical constructive species in the Chinese Tianshan forest ecosystem with important ecological values. In this study, P. schrenkiana at three altitude gradients were selected to study its water sources during the growing season (June to September) in the natural forest conservation area of the northern slope of Tianshan Mountains. The hydrogen-oxygen stable isotope technique was used to determine the δ18O values of xylem water and soil water levels. In addition, the relationships between xylem water or soil water δ18O values and altitude were analyzed, and the IsoSource model was used to quantify the water sources of P. schrenkiana at different altitudes. The results showed that: (1) the δ18O of soil water at the three elevations were depleted in April and enriched from May to September. The δ18O values of stem water at 1450 m elevation showed the greatest variation between months, while the δ18O of stem water was gradually enriched at the three elevations from June to September; (2) the 0-0.2 m soil water contributed more than half of the P. schrenkiana water requirement at the three elevations during the growing season, with the surface soil water average contribution rates of 61.37%, 51.35%, and 58.42% in the high, middle, and low elevations, respectively. In May and June, P. schrenkiana tended to use soil water in all layers equally, and no significant shift in the plant water uptake was observed during the growing season. In addition, the water absorption of P. schrenkiana mainly occurred at 0-0.2 m soil water level, suggesting that it could rapidly absorb rainfall water, which can improve soil hydrology and reduce the damage caused by extreme rainfall. Therefore, strengthening the protection management of P. schrenkiana forests can effectively improve the water conservation capacity of forests and enhance their ecological benefits. Figures and Tables | References | Related Articles | Metrics

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Comparative analysis of summer water sources of different shrubs on the northern slope of Tianshan Mountains by MixSIAR and IsoSource models LI Hongmei, Bahejiayinaer TIEMUERBIEKE, CHANG Shunli, Gulihanati BOLATIBIEKE, ZHANG Yutao, LI Jimei 2023, 40 (3):  445-455.  doi: 10.13866/j.azr.2023.03.11 Abstract ( 712 )   HTML ( 40 )   PDF (8858KB) ( 135 )   This study aims to provide reference for quantifying the selection model of plant water sources. MixSIAR model and IsoSource model are commonly used to quantify plant water sources by combining hydrogen and oxygen stable isotope technology. However, different models yield varying quantitative results. Hence, choosing the best model is important to reduce the uncertainty of results. In this work, the hydrogen and oxygen stable isotope compositions of stem xylem water and each potential water source of two shrubs were measured from July to September in 2019 and 2021. The dominant tree species Cotoneaster melanocarpus and Berberis heteropoda in the premontane shrub zone of the northern slope of Tianshan Mountain were selected as subjects. MixSIAR and IsoSource models were used to quantify plant water sources, and their results were compared and evaluated according to the root mean square error (RMSE) and parameter R. Results showed (1) differences in the quantification results of the two models for the main potential water sources of plants. These differences were related to the calculation principles of the two models. (2) Under the premise that the two models quantify the same main potential water sources of plants, the IsoSource model quantifies larger values than the MixSIAR model. (3) The results of RMSE and parameter R showed that the error of IsoSource model in quantifying plant water sources was smaller than that of MixSIAR model possibly due to the large difference between C. melanocarpus and B. heteropoda In summary, the MixSIAR model may be more accurate in quantifying the similarity of plant water sources than the IsoSource model. Figures and Tables | References | Related Articles | Metrics

Ecology and Environment

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Spatiotemporal changes of habitat quality before and after the implementation of Grain for Green Project in the middle reaches of the Yellow River CHEN Shi, HUANG Yinlan, JIN Yunxiang 2023, 40 (3):  456-468.  doi: 10.13866/j.azr.2023.03.12 Abstract ( 266 )   HTML ( 10 )   PDF (15154KB) ( 133 )   It is of great practical significance for the ecological protection, rehabilitation, and high-quality development of the middle reaches of the Yellow River to analyze the spatial and temporal characteristics of habitat quality and its development trend. On the basis of the land cover data of the European Aeronautics and Space Administration from 1992 to 2020, the InVEST model was used to estimate the habitat quality. Sen+MK test and Hurst index analysis methods were applied to explore the spatial and temporal changes and development trends of the habitat quality in the middle reaches of the Yellow River before and after the implementation of the Grain for Green Project. Results showed that the habitat quality in the middle reaches of the Yellow River was good overall in recent 29 years, with the average habitat quality index of 0.652. However, a slight downward trend was observed (a drop of 0.004 per decade). Meanwhile, the habitat quality in the Grain for Green area showed an upward trend (an increase of 0.174 per decade), of which the most significant reached 0.656 recorded from 2011 to 2020. The spatial and temporal changes of habitat quality in the middle reaches of the Yellow River from 2001 to 2020 mainly showed an obvious decrease trend. In terms of the development of different time periods, the area with good habitat quality in 2011-2020 increased compared with that in 2001-2010. This finding was reflected in the improvement of habitat quality in the Grain for Green area. In the future, the temporal and spatial changes of habitat quality in the middle reaches of the Yellow River will be dominated by obvious decrease and obvious increase trends, respectively, and the sustainability will be strong. The significantly reduced areas will be mainly distributed in the Fenwei plain and the urban centralized development areas, and the significantly increased areas will be mainly located in the border areas of Shanxi Province, Shaanxi Province and Inner Mongolia Autonomous Region. Figures and Tables | References | Related Articles | Metrics

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The spatiotemporal patterns of water ecological footprints, depth, size, and influencing factors in Shaanxi Province MA Xiaolei,QIAO Yaqi,WANG Jie,JIAO Shixing,ZHANG Man 2023, 40 (3):  469-480.  doi: 10.13866/j.azr.2023.03.13 Abstract ( 334 )   HTML ( 15 )   PDF (11945KB) ( 73 )   This study measured the spatiotemporal evolution of water ecological footprint, size, and depth in the Shaanxi Province from 2000 to 2019. In addition, the “cross-section fixed effects model” was used to build an indicator system based on the factors influencing water ecological footprint, including economy, population, environment, agriculture, and water conservancy. The results show that: (1) An upward flactuating trend occurred in the water ecological footprint of Shaanxi Province, with a multi-year average of 14.03 million hm2, and agricultural water accounted for the hight average proportion of ecological footprint with 66.65%, while industrial and domestic water accounted for 15.84% and 13.39%, respectively; (2) The interannual distribution of water ecological carrying capacity showed an unbalanced and fluctuating trends with specific values between 6.035 and 37.41 million hm2. The annual average of water ecological carrying capacity in Shaanxi was 16.329 million hm2, which was higher than the water ecological footprint, and showed a surplus water ecological state; (3) In the past ten years, Shaanxi Province mainly consumed the flow capital of water resources, and the size of the water ecological footprint was at high level. However, a large stock capital consumption of water resources occurred in 2001 and 2016; (4) A large difference in the regional water ecological carrying capacity and water ecological footprint was observed in Shaanxi Province, but with a relatively small inter annual change; (5) The economic development level, population, and reservoir storage capacity showed a significant positive impact on the water ecological footprint of Shaanxi Province. To strengthen the ecological carrying capacity of water resources, Shaanxi Province should further improve and consolidate the construction of water conservancy facilities, increase the reservoir capacity, improve the water resources management system, and strengthen the rigid constraints on water resources. Figures and Tables | References | Related Articles | Metrics

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Evaluation of Dongzhi Loess Plateau Gully development based on combined entropy weight Rank-Sum Ratio method CUI Shuai, XU Qiang, YUAN Shuang, PU Chuanhao, CHEN Wanlin, JI Xu 2023, 40 (3):  481-491.  doi: 10.13866/j.azr.2023.03.14 Abstract ( 259 )   HTML ( 10 )   PDF (12412KB) ( 46 )   As a typical erosion geomorphic unit in the loess areas, gullies continuously erode loess surface under the action of internal and external forces, rainfall, and other factors. There are significant differences in the degree of development of gullies and valleys. Evaluating the development pattern of gullies and valleys can enhance the understanding of their organized, systematic formation and evolution. In addition, comprehensive quantitative indexes can facilitate the understanding of the longitudinal, lateral, and horizontal characteristics of gullies and valleys from multiple perspectives, which can help in the accurate and effective implementation of gully consolidation and loess protection projects, and reduce the constraints on development caused by this fragile geological environment. Evaluating the development of loess valleys is also crucial for exploring the intrinsic mechanism of valley formation, soil erosion, and guiding the ecological restoration of loess areas. In this study, ten quantitative indicators of gully development were selected based on the horizontal spatial, climatic, and point-line characteristics of the gullies, and used to establish an indexed evaluation model of the developmental stages of Dongzhi Loess Plateau gullies based on the efficient multi-factor comprehensive indexing evaluation capacity of the combined entropy-weight rank-sum ratio (RSR) method. Results showed that: (1) The highest weight of 16.08% could be attributed to the normalized vegetation index (NDVI) based on the entropy weighting method, followed by gully density (15.621%), both of which are important indicators for predicting the degree of gully development. (2) The combined entropy weighting RSR method could classify the 82 gullies of Dongzhi Loess Plateau into juvenile, youth, prime, and old age categories, with the percentage of gully area under the prime and old age categories accounting for 88.48% and 88.48%, respectively, while the eastern and northern parts of Dongzhi Loess Plateau exhibited more developed features and strong erosion on the loess surface. (3) The degree of gully development was highly correlated with the underlying palaeomorphology, tectonic geology, and loess thickness. (4) A significant model variance consistency test at P<0.001, with a linear regression R2 fit of 0.986 was observed, which indicated a good performance of the model. Figures and Tables | References | Related Articles | Metrics

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Spatial-temporal evolution characteristics of land use change and habitat quality in the Lhasa River Basin over the past three decades WANG Peng, QIN Sitong, HU Huirong 2023, 40 (3):  492-503.  doi: 10.13866/j.azr.2023.03.15 Abstract ( 353 )   HTML ( 22 )   PDF (17014KB) ( 103 )   This study used the Lhasa River Basin, which is a typical plateau basin to clarify the spatiotemporal characteristics of land use change and its impact on a plateau basin habitat quality. The google earth engine (GEE) platform and random forest classification algorithm were used to interpret the land use information of the Lhasa River Basin from 1990 to 2020, and to analyze the spatiotemporal dynamic changes of land use in the past 30 years. The InVEST model was integrated to evaluate the habitat quality of the basin, and to explore the characteristics of its habitat quality changes. The results showed that the efficiency and accuracy of land use classification improved by selecting the vegetation growing season, supplementing and replacing missing data with images obtained in the previous and following years, and generating annual composite cloud free images for land use classification in the alpine and high-altitude areas. An optimal RF classification model combining the spectral, textural, and topographical features of Landsat images was established to classify land use information in the plateau basin. The observed OA, Kappa coefficient, and the F1-score were 88.16%, 0.84, and 0.70, respectively. Since the 1990, the features of the land use change in the Lhasa River Basin have been characterized by “five increases and three decreases,” with an increase being observed in the areas under grassland, construction, forest land, wetland, and water, while the areas under cultivated land, glaciers, and permanent snow or unused land having a decrease. Among them, the growth rate of construction land had the largest increase of 288.35%, while the largest decrease was detected in cultivated land with 50.18%, which could mainly be attributed to overpopulation in the urban areas. Most significant decrease occurred in the unused land area, and the changed area was mainly converted with grassland. During the study period, high quality habitats were mainly distributed in the downstream areas, southwest, and the main source areas of the basin, included the grassland, water, glaciers, permanent snow, and wetland. Poor qualities of habitats were observed in the Lhasa municipal district, Dazi District, Linzhou County, Qushui County, and Mozhugongka County, as well as in the unutilized land in the middle and upper reaches of the basin. The overall habitat quality of the watershed showed an alternating transition pattern of initial decrease, then increase, followed by a decrease, and a slowed down transition, while the habitat quality index increased from 0.53 to 0.57. Population growth and rapid urbanization accelerated the expansion of urban areas and the reduction of arable land, while climate change and ecological engineering played a positive role in improving the quality of habitat in Lhasa River Basin. This study provides a scientific basis and reference for formulating ecological restoration strategies, sustainable land use, and habitat quality improvement in a plateau area. Figures and Tables | References | Related Articles | Metrics

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Remote sensing monitoring of aeolian desertification in Ongniud Banner based on GEE MA Haowen, WANG Yongfang, GUO Enliang 2023, 40 (3):  504-516.  doi: 10.13866/j.azr.2023.03.16 Abstract ( 443 )   HTML ( 24 )   PDF (8085KB) ( 159 )   In this study, google earth engine (GEE) was used to extract the normalized difference vegetation index (NDVI) and Albedo parameters. The NDVI-Albedo space was constructed to monitor aeolian desertification in Ongniud Banner from 1991 to 2015, and the influence of key driving factors and mechanism of aeolian desertification in Ongniud Banner were analyzed using geographical detectors combined with natural and anthropogenic factors. The following key results were obtained: (1) Aeolian desertification in Ongniud Banner first experienced the development of evolution process, which then was reversed. During the development period from 1991 to 2000, the total area of aeolian desertified land increased by 2130.29 km2, with extremely severe changes in both aeolian and non-aeolian desertified land, which had dynamic attitudes of 9.5 and -4.8, respectively. From 2000 to 2015, the total desertified land area of aeolian decreased by 3364.61 km2, and the extreme severe aeolian and non-aeolian desertification land were the main changes, with dynamic attitudes of -4.2 and 8.3, respectively; (2) The extreme areas of aeolian desertification in the Ongniud Banner were mainly distributed in the central east and the north of Xiliaohe Plain, while the aeolian desertification in most areas of Jibeiliaoxi Mountain in southwest region is relatively light. From the perspective of transfer, the development area of various types of aeolian desertification land was 5333.75 km2, while the reversed area from 1991 to 2000 was 1157.29 km2. Notably, the non-aeolian desertified to moderate aeolian desertified land area was the largest covering 1000.24 km2. From 2000 to 2015, the development area of all types of aeolian desertified land was only 424.65 km2, while the reversed area was 7041.80 km2. The area of moderate desertified land covering 1449.74 km2 was reverted to non-desertified land; (3) From 1991 to 2000, both natural and anthropogenic factors drove the aeolian desertification process in the study area, with terrain and sand source as the main reasons for the formation of spatial distribution pattern of aeolian desertified land in Ongniud Banner. The warm and dry climate conditions, as well as intensified human activities led to the development of aeolian desertification in Ongniud Banner. From 2000 to 2015, aeolian desertification reversal was driven by the implementation of a series of anti-desertification policies and the improvement of natural conditions. Figures and Tables | References | Related Articles | Metrics