Table of Content

15 September 2023, Volume 40 Issue 9 Previous Issue    Next Issue

Weather and Climate

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Spatiotemporal distribution of precipitation in five Central Asian countries based on FY-4A quantitative precipitation estimates CHEN Aijun,Yin 2023, 40 (9):  1369-1381.  doi: 10.13866/j.azr.2023.09.01 Abstract ( 408 )   HTML ( 61 )   PDF (14655KB) ( 226 )   The FY-4A Quantitative Precipitation Estimation (QPE) product is crucial for comprehensive research on precipitation patterns and spatiotemporal distribution across Central Asian (CA) countries. In this study, FY-4A QPE data quality was evaluated using the Integrated Multi-satellite Retrievals for Global Precipitation Measurement Final run (IMERG-F), and the precipitation characteristics and spatiotemporal distribution over five CA countries were subsequently examined. The main findings were as follows. (1) FY-4A QPE accurately reflected precipitation spatial disparities across the CA countries, aligning well with the temporal changes of IMERG-F. (2) Annual average precipitation (AAP) exhibited substantial spatial variation over the CA countries in relation to altitude. High-altitude regions exceeded 500 mm AAP, encompassing <10% of the area, whereas low-altitude areas experienced <350 mm AAP, accounting for >90% of the region. (3) Precipitation distribution exhibited pronounced seasonality across the five CA countries. Summer exhibited the widest precipitation range, averaging >50 mm. Conversely, the autumn average, typically <40 mm, was the lowest. Kyrgyzstan and Tajikistan experienced sufficient precipitation year-round, with some areas showing an average >480 mm. However, central and western Kazakhstan, Uzbekistan, and northern Turkmenistan received <40 mm. (4) According to clustering of areas with a monthly average precipitation exceeding 40 mm, the five CA countries were classified into four spatial distribution types: point discrete, drought, semi-dry and semi-wet, and sandwich. (5) In summer across the five CA countries, areas with elevated precipitation density displayed a near 3-hour cyclic daily variation. Notably, one of these periods occurred from noon to the first half of the night. Furthermore, the predominant precipitation type was light rain, with a minor occurrence of moderate rain. Figures and Tables | References | Related Articles | Metrics

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Liftoff velocity distribution model of aeolian sand grains in saturated wind-sand flow JIANG Chanwen,WANG Xiaoyan 2023, 40 (9):  1382-1390.  doi: 10.13866/j.azr.2023.09.02 Abstract ( 218 )   HTML ( 11 )   PDF (5218KB) ( 140 )   The probability distribution function (PDF) of the liftoff velocities of aeolian (wind-blown) sand particles, an important parameter in sediment transport and dust emission models, remains poorly understood due to the challenges in tracking particle dynamics during the liftoff process. To reliably describe this distribution function, measurements of the individual particle trajectories near the sand-bed during sediment transport are required. In this study, we address this issue by employing an improved particle tracking velocimetry technique, enabling us to capture the particle-bed collision process of many liftoff grains in consecutive images and, consequently, to obtain multiple liftoff particle trajectories with different liftoff modes during sand transport in a boundary layer wind tunnel. Subsequently, using the wind tunnel, we measured the trajectory of splash particles, rebound particles that generated no splash particles, and rebound particles that generated only one splash particle near the sand bed. By analyzing the probability distribution of the liftoff velocities of these three liftoff modes, a probability distribution model for the liftoff velocities of particles in a steady-state wind-sand flow was constructed. The results indicate the following: (1) The liftoff angles and speeds of the three liftoff modes all follow a Lognormal probability distribution. (2) The PDF for the liftoff angle of the total liftoff particles is largely unaffected by the liftoff mode. (3) The PDF for the liftoff velocity of the total liftoff particles is mainly controlled by the number of splash particles to that of rebound particles. This indicates that the development process of wind-sand flow or turbulence fluctuations impacts the PDF of liftoff velocity. The different shapes of the probability distribution curve for liftoff velocities may only reflect the specific development of wind-sand flow. Our results offer new insights into the aeolian sand saltation process near the bed surface and are crucial for simulating particle-bed interactions and improving geomorphic dynamics models in aeolian sand transport. Our study on the probability distribution model of liftoff velocity opens a new avenue of investigation in the aeolian and soil sciences and aids the understanding of the dynamics of near-bed particle transport. This transport plays an essential role in aeolian research, as well as in the geomorphodynamics of Earth, Mars, and other celestial bodies within our solar system. Figures and Tables | References | Related Articles | Metrics

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Objective weather classification of persistent floating dust weather in the Tarim Basin ZHU Congzhen,ZHAO Tianliang,MENG Lu,YANG Xinghua,HE Qing,Ali MAMTIMIN 2023, 40 (9):  1391-1403.  doi: 10.13866/j.azr.2023.09.03 Abstract ( 188 )   HTML ( 16 )   PDF (28061KB) ( 113 )   This study utilized observational data on floating dust days from multiple stations across the Tarim Basin spanning 2011 to 2020. In total, 396 days characterized by persistent floating dust were selected. Employing ERA5 meteorological reanalysis data, the PCT algorithm was used to objectively classify near-surface and upper-layer circulation patterns associated with persistent floating dust in the Tarim Basin. Furthermore, typical synoptic processes accompanying persistent floating dust were selected for analysis. The aim was to elucidate the relationship between persistent floating dust and synoptic circulation at different altitudes. The findings revealed three distinct near-surface weather patterns during persistent floating dust days: high-pressure front, high-pressure bottom, and uniform pressure field. Variations in meteorological conditions and pollutant concentrations were evident among these surface weather patterns. The near-surface weather system evolved from the high-pressure front to high-pressure bottom, culminating in the uniform pressure field. The upper-layer weather system alternated between the westerly trough type and the high-pressure ridge-zonal latitudinal type. As the Siberian cold high-pressure system moved eastward and southward, upper-layer circulations were influenced by the westerly trough and the Iranian high-pressure system. Persistent floating dust events occurred and developed alongside elevated near-surface PM10 concentrations. These events concluded when a near-surface uniform pressure field prevailed, marked by limited air pressure system activity and an upper-layer circulation characterized by the zonal latitudinal pattern. Figures and Tables | References | Related Articles | Metrics

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Water vapor transport mechanisms for varied precipitation grades during the summer half-year in Yinchuan Plain WANG Nana,HAN Lei,LIU Lili,PENG Ling,ZHOU Peng,Ma Yunlei,Ma Jun 2023, 40 (9):  1404-1413.  doi: 10.13866/j.azr.2023.09.04 Abstract ( 177 )   HTML ( 21 )   PDF (9511KB) ( 99 )   Global warming intensifies regional water cycles and alters water vapor transport routes. Investigating stable isotope traits in diverse precipitation grades and identifying water vapor origins can offer insights for efficient water resource utilization and drought-flood management. By analyzing precipitation samples from Yinchuan Plain in the May-October summer half-years of 2018-2020, the hydrogen and oxygen isotope fluctuations across precipitation levels and their secondary evaporation effects were estimated in this study. Backward trajectory modeling and water vapor flux methods were applied to determine vapor sources and potential evaporation areas. The findings revealed that the stable isotope signature in Yinchuan Plain during the summer half-year decreased with increased rainfall levels; light rain exhibited negative d-excess values, whereas moderate and heavy rains showed positive values. The slope and intercept of the regional atmospheric precipitation line diminished as rainfall magnitude increased. Secondary evaporation intensified with higher air temperature, but decreased with increased precipitation, air relative humidity, and raindrop diameter. Distinct water vapor origins existed across precipitation levels: westerly vapor dominated light rain, whereas moderate and heavy rains originated not only from westerly vapor but also from high latitude land evaporation vapor and southeast ocean vapor, respectively. Potential evaporative vapor source areas predominantly influenced light and moderate rainfall, encompassing the study area’s vicinity as well as northwest and southeast regions. Moderate rainfall events were largely observed in the study area’s vicinity, as well as northwest and southeast regions, whereas heavy rainfall clustered around the study area and the southeastern region. Figures and Tables | References | Related Articles | Metrics

Land and Water Resources

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Runoff trend and attribution analysis of the Zhengyi Gorge in the middle reaches of the Heihe River HU Guanglu,TAO Hu,JIAO Jiao,BAI Yuanru,CHEN Haizhi,MA Jin 2023, 40 (9):  1414-1424.  doi: 10.13866/j.azr.2023.09.05 Abstract ( 217 )   HTML ( 24 )   PDF (5393KB) ( 621 )   This study utilized measured runoff data from the Zhengyi Gorge hydrological station in the middle reaches of the Heihe River to analyze the trend and mutation years of the runoff sequence from 1970 to 2020. Various methods, including linear regression, the Mann-Kendall mutation test, the sliding T mutation test, the Pettitt test, and cumulative offset verification, were employed for the analysis. Additionally, an attribution analysis of the runoff changes at the Zhengyi Gorge hydrological station was conducted using the Budyko water-energy coupled balance equation. The results indicate the following: (1) Over the study period, the runoff at Zhengyi Gorge showed fluctuations, alternating between periods of abundance and contraction but showed an overall increasing trend. The runoff experienced a mutation in 2004, resulting in a 3.08 × 108 m3 increase in average annual runoff volume, representing a growth rate of 32.7%. (2) In the period after the mutation (2005-2020), the elastic coefficients of runoff in response to precipitation, potential evaporation, and underlying surface parameters were 1.40, -0.40, and -1.57, respectively. The contribution rates of each factor to runoff were 42.73%, -12.52%, and 69.79%, respectively, indicating that runoff is most sensitive to underlying surface changes and that precipitation has a more significant impact on runoff than potential evaporation among climate factors. (3) Under certain regional climatic conditions, the changes in the underlying surface of the middle reaches caused by human activities, such as vegetation cover, land use, and watershed water transfer, are the main reasons for the changes in runoff at Zhengyi Gorge. The research findings can provide a scientific basis for river basin management departments to formulate water resource allocation and utilization plans. Figures and Tables | References | Related Articles | Metrics

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Distribution and coenrichment of arsenic and fluorine in the groundwater of the Manas River Basin in Xinjiang KANG Wenhui,ZHOU Yinzhu,SUN Ying,ZHOU Jinlong,CAO Yueting,LU Han,TU Zhi 2023, 40 (9):  1425-1437.  doi: 10.13866/j.azr.2023.09.06 Abstract ( 195 )   HTML ( 25 )   PDF (18519KB) ( 105 )   Arsenic (As) and fluoride (F) pollution in water bodies, along with their coexistence, are critical environmental concerns, with long-term exposure posing a significant threat to public health. This study focuses on the Manas River Basin as the research area, analyzing the hydrochemical, and spatial distribution characteristics of groundwater with high As and F content. Furthermore, the study aims to elucidate the hydrogeochemical processes related to the origin, migration, and enrichment of As, and F in groundwater, considering geological conditions, occurrence environments, and the influence of human activities. The results show that the groundwater in the study area exhibits an alkaline-reducing environment. The mass concentrations of As and F in groundwater range from 1.13 to 41.35 μg·L-1 and from 0.06 to 8.02 mg·L-1, respectively. Groundwater samples with high As and F content constituted 62.9% and 45.7% of the total samples, respectively, while samples with a coenrichment of As and F accounted for 37.1% of the total samples. As-F coenriched groundwater is mainly distributed in the northern plain region, near the edge of the desert, with the dominant hydrochemical types being HCO3·Cl and HCO3·SO4·Cl. The primary sources of As and F in groundwater are high-content rock strata found in the southern mountainous area of the Manas River Basin. The high pH value, low SO42-/Cl- molar ratio, and low Eh of the high-As-content groundwater in the Manas River Basin indicate that a weak alkaline-reducing environment facilitates As enrichment in groundwater. Conversely, groundwater with high F content is characterized by high pH, HCO3-, and Na+ levels, as well as low Ca2+, indicating that an alkaline environment with high Na+ and low Ca2+ content favors F enrichment in groundwater. Figures and Tables | References | Related Articles | Metrics

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Monitoring of Hulun Lake water level changes based on ICESat-2 satellite altimetry data LIU Junyan,WANG Shijie 2023, 40 (9):  1438-1445.  doi: 10.13866/j.azr.2023.09.07 Abstract ( 296 )   HTML ( 21 )   PDF (4715KB) ( 374 )   The water level changes of grassland lakes indicate the changes of grassland ecological environment, which is an important indicator of grassland ecological changes. We use the ATL13 global inland water data of ICESat-2 satellite from November 2018 to January 2022 to construct a high-precision water level change sequence of Hulun Lake. The results are verified using DAHITI, Hydroweb, and G-REALM water level data. Based on the relationship between lake area and water level change, a water level area relationship model is constructed to analyze the seasonal characteristics of lake water level changes and the influence of external factors on lake water level. The research results showed that: from November 2018 to January 2022, the water level of Hulun Lake showed an overall upward trend, with an average annual water level rise rate of 0.49 m·a-1. The water level of the lake decreases from March to June each year, rises from July to October, and stabilizes from November to February of the following year. It is known from the comparison and verification with DAHITI, Hydroweb, and G-REALM water level data that the ICESat-2 satellite monitoring water level data is stable, the water level sequence precision is high, and the root mean square error is 9.7 cm, which is reliable. The Combination of the ICESat-2 satellite water level monitoring results and the lake water level area model can achieve multi-time and high-precision lake water level monitoring, and calculate the time series of water level seasonal changes, which showed that the seasonal characteristics of Hulun Lake water level are obvious, and the inter annual trend is basically stable. The water level decreases from spring to summer and rises from summer to winter. The changes of lake water level is greatly affected by external factors. The increase of evaporation caused by the rise of temperature is the main factor leading to the decrease of lake water level. The temperature, evaporation, and water level change showed a strong negative correlation. The recharge of the lake water volume by artificial water injection has increased the lake level and the trend of increasing water level is obvious during the injection period in 2021. Figures and Tables | References | Related Articles | Metrics

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Effects of conservation tillage on soil nitrogen mineralization in dry wheat fields on the Loess Plateau PANG Ye,YUAN Jianyu,YAN Lijuan,DU Mengyin,LI Guang 2023, 40 (9):  1446-1456.  doi: 10.13866/j.azr.2023.09.08 Abstract ( 156 )   HTML ( 12 )   PDF (5204KB) ( 156 )   Soil nitrogen mineralization is an important process in the nitrogen cycle of terrestrial ecosystems and is vital for maintaining soil nitrogen supply capacity and crop growth. The semiarid region of the Loess Plateau in central Gansu is an important grain production area in Northwest China, and realizing efficient nitrogen utilization in local dry farmland is a key research focus. However, little is known about the effects of different tillage measures on soil nitrogen mineralization in dry wheat fields in this region. Therefore, this study focuses on the dryland wheat fields in the Loess Plateau and uses the resin core in situ culture method to monitor the effects of different tillage measures [traditional tillage (T), no-tillage (NT), traditional tillage + straw mulching (TS), and no-tillage+straw mulching (NTS)] on soil nitrogen mineralization during the spring wheat growth period (March-August) in 2021. This study analyzes the effects of these tillage measures on soil nitrogen content and hydrothermal conditions to understand their impact on the soil nitrogen mineralization process. The results indicate the following: (1) Soil nitrogen under T, NT, TS, and NTS treatments showed a net nitrogen fixation state during the early stage of spring wheat growth (presowing-flowering stage) and a net nitrogen mineralization state during the middle and late stages (flowering-maturity stage). There were significant differences in the soil net nitrogen mineralization rate under different tillage measures (NTS>TS>NT>T). (2) Compared with the T treatment, three conservation tillage methods increased soil total nitrogen, NH4+-N content, and moisture during the growth period of spring wheat while reducing soil NO3--N content and temperature accumulation. (3) The correlation analysis showed that soil nitrogen content and soil water and heat were the key factors affecting the soil net nitrogen mineralization rate. However, the influencing factors regulating soil nitrogen mineralization at different incubation stages varied. In conclusion, NTS treatment promotes soil nitrogen mineralization, improves soil nitrogen supply and water retention capacity, and is crucial for maintaining and restoring farmland productivity in the semiarid region of the Loess Plateau. Figures and Tables | References | Related Articles | Metrics

Plant Ecology

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Changes in vegetation biomass and its relationship with soil carbon during restoration processes in degraded sandy grasslands ZHOU Jing,SUN Yongfeng,DING Jieping,BAI Haojiang,MA Xiang,WANG Xuyang,Luo Yongqing 2023, 40 (9):  1457-1464.  doi: 10.13866/j.azr.2023.09.09 Abstract ( 154 )   HTML ( 25 )   PDF (3705KB) ( 165 )   The allocation pattern of plant biomass and its input into the soil are key processes for restoring degraded sandy grassland, especially regarding soil carbon accumulation. In this study, mobile dunes, semifixed dunes, fixed dunes, and fenced grasslands in Horqin Sandy Land at different restoration stages were investigated. By analyzing the biomass allocation of herbaceous vegetation, root traits, soil physicochemical properties, and their interrelations, it was found that the aboveground biomass, root biomass, surface litter, and underground necromass all increased significantly (P<0.05) with the extent of desertified grassland restoration. Compared to severely desertified mobile dunes, the total dry matter (biomass+litters) in semifixed dunes, fixed dunes, and fenced grasslands increased by 11.01%, 116.29%, and 151.18%, respectively. Similar to the changes in biomass, soil carbon content also increased significantly (P<0.05) with the extent of desertified grassland restoration, with a higher increase rate observed in the 0-10 cm layer than the 10-20 cm layer. Structural equation modeling indicated that the soil carbon content in the 0-10 cm layer was influenced by the surface litter mass, underground necromass, and root surface area. Conversely, soil carbon content in the 10-20 cm layer was affected only by underground necromass and root surface area. Moreover, the soil carbon content in both layers showed an insignificant relationship with aboveground biomass. In conclusion, the soil carbon content in degraded sandy grassland is primarily affected by litter input and root traits but has an insignificant relationship with aboveground biomass. Figures and Tables | References | Related Articles | Metrics

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Effects of saline-alkali stress on organic osmoregulatory substances and antioxidant enzyme systems of Helianthus tuberosus QIAN Yue,LI Siyuan,RAO Liangyi 2023, 40 (9):  1465-1471.  doi: 10.13866/j.azr.2023.09.10 Abstract ( 150 )   HTML ( 9 )   PDF (2000KB) ( 122 )   To reveal the physiological response of typical crops to saline-alkali stress, we selected Jerusalem artichoke (Helianthus tuberosus) as our research object. We set up three different treatments: a complete nutrient soil group (CK), a light saline-alkali soil group (LS), and a moderate saline-alkali soil group (MS). Changes in physiological indicators, such as organic osmoregulatory substances (soluble sugar, soluble protein, and proline); malondialdehyde (MDA) content; and activities of antioxidant enzyme systems [superoxide dismutase (SOD), peroxide dismutase (POD), and catalase (CAT)] of Helianthus tuberosus were investigated. The results showed the following: (1) The content of organic osmoregulatory substances in Jerusalem artichoke leaves, including soluble sugar, proline, and soluble protein, increased under different intensities of saline-alkali stress. (2) The groups had no significant differences in MDA content. However, with increased saline-alkali stress intensity, the activity indexes of antioxidant enzyme systems, such as SOD, POD, and CAT, in Jerusalem artichoke leaves showed an upward trend. After 150 days of saline-alkali stress, the SOD activity in the LS and MS groups increased significantly by 22.13% and 26.49%, respectively, compared to the CK group. Additionally, CAT activity in the LS and MS groups increased significantly by 81.66% and 92.38%, respectively, compared to the CK group (P < 0.05). Moreover, POD activity in the MS group was significantly higher than in the CK group during the same period. The above findings demonstrate that Helianthus tuberosus can adapt to a saline-alkali environment by increasing the content of osmoregulatory substances (soluble sugar, soluble protein, and proline) and activating the antioxidant enzyme system (SOD, CAT, and POD), indicating its strong tolerance to saline-alkali stress. Figures and Tables | References | Related Articles | Metrics

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Study on using deep learning method to retrieve the biomass of natural Picea forest from GEDI data SUN Danyang,WEI Jianxin,YANG Liao,WANG Jie,TANG Yuqi,Babierjiang DILIXIATI 2023, 40 (9):  1472-1483.  doi: 10.13866/j.azr.2023.09.11 Abstract ( 254 )   HTML ( 28 )   PDF (25975KB) ( 86 )   As the largest carbon reservoir on land, forests play a crucial role in human life and development. Understanding the dynamic changes in forest resources and modernizing their sustainable development is currently a significant research focus. This study focuses on natural Picea forests in the Tianshan Mountains and uses ground measurement data, helicopter airborne LiDAR point cloud data, and Global Ecosystem Dynamics Investigation (GEDI) data to construct a multisource fusion data framework. By utilizing deep learning algorithms within the AutoKeras framework, the study aims to predict the regression model of multiple relative height quantiles of GEDI data and their aboveground biomass in the study area, thereby validating the feasibility of GEDI data for large-scale aboveground biomass retrieval. The main conclusions are as follows: (1) GEDI data are highly feasible for estimating forest aboveground biomass. Through automated deep learning algorithms and training and verification sets, the overall data achieve a coefficient of determination (R2) of 0.69, 0.63, and 0.67, respectively, along with a mean absolute error of 3.73 mg·hm-2, 4.22 mg·hm-2, and 3.89 mg·hm-2, demonstrating high prediction accuracy. (2) Helicopter LiDAR, an intermediate technology for estimating aboveground biomass using GEDI data, exhibits a single tree recognition accuracy of over 0.75 across the study area. The study successfully utilizes multimodal data fusion to quantitatively describe the structural parameters of the single tree foundation in the study area while verifying the potential of GEDI data for obtaining forest aboveground biomass. Moreover, the study provides a theoretical basis for estimating carbon sources and sinks, biomass, stock, forest management, biodiversity protection, and other projects in similar areas, offering essential guidance, and fundamental data support. Figures and Tables | References | Related Articles | Metrics

Ecology and Environment

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Spatiotemporal dynamics of grassland vegetation and its responses to climate change in Changji Hui Autonomous Prefecture, Xinjiang CHEN Chunbo,LI Junli,ZHAO Yan,XIA Jiang,TIAN Weitao,LI Chaofeng 2023, 40 (9):  1484-1497.  doi: 10.13866/j.azr.2023.09.12 Abstract ( 188 )   HTML ( 31 )   PDF (17088KB) ( 122 )   As the most widespread ecosystem on Earth, grassland is vital for maintaining ecological security, sustainability, and human well-being. In this study, we used systemic methods of maximum synthesis, regression analysis, and partial correlation analysis to investigate the spatiotemporal dynamics of grassland and its responses to temperature and precipitation on the northern slope of the Tianshan Mountains in Changji Hui Autonomous Prefecture, Xinjiang, from 2000 to 2020. The research was based on remote-sensed time series images (e.g., MODIS NPP and EVI) and related auxiliary data. The results indicate a significant increase in grassland NPP and EVI from 2000 to 2020, with temporal fluctuations. However, after 2016, both NPP, and EVI declined year over year. Over the past 20 years, the mean average NPP, and EVI of grassland vegetation were 0.095 kg C·m-2 and 0.186, respectively. In 2020, grassland NPP (0.099 kg C·m-2）and EVI (0.194) increased by 28.57% and 16.87%, respectively, compared to their values in 2000 (NPP: 0.077 kg C·m-2; EVI: 0.166). The spatial heterogeneity of grassland vegetation NPP increased substantially and showed a trend toward expansion, while the spatial heterogeneity of grassland EVI increased annually. The range of variation observed during this research was 0.038 kg C·m-2 for NPP and 0.059 for EVI. Overall, the spatial distribution of grassland NPP and EVI was generally coherent, but variations also existed. Grassland NPP and EVI showed an upward trend with altitude, with an elevated EVI along the oasis edge and the southern edge of the Gurbantunggut Desert. In this study, we suggest that abundant water and heat induce the formation of vigorous layers of short-lived plants, resulting in higher coverage than other grassland plants after withering. These short-lived plants begin their life cycle in early spring, when hydrothermal conditions (e.g., temperature, soil moisture, and root zone soil temperature) are favorable, and they complete their germination, growth, fruiting, and withering phases from April to June. The area percentages of NPP (65.01%) and EVI (21.93%) showed a significant increasing trend on the northern slope of Tianshan Mountains in the Changji Hui Autonomous Prefecture, Xinjiang, over the last 20 years. The proportion of vegetation NPP and EVI in the 9 grassland types showed a significant positive correlation with precipitation, which was much greater than that with temperature during the same period, confirming that precipitation is the major factor affecting grassland vegetation. Furthermore, the reactions of each grassland vegetation type (e.g., NPP and EVI) to precipitation varied. While precipitation remained a key driver for grassland, moderate warming, especially at high altitudes, was found to be suitable for the growth of grassland vegetation. These findings provide theoretical references for evaluating grassland ecological health and degradation, as well as the high-quality development of grassland on the northern slope of Tianshan Mountains in the Changji Hui Autonomous Prefecture, Xinjiang. Figures and Tables | References | Related Articles | Metrics

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Remote sensing monitoring of the ecological environment of hydropower station construction and operation in arid areas： A case study of Longyangxia Hydropower Station MA Yaoyao, SHI Peijun, XU Wei, ZHANG Gangfeng 2023, 40 (9):  1498-1508.  doi: 10.13866/j.azr.2023.09.13 Abstract ( 169 )   HTML ( 37 )   PDF (16518KB) ( 92 )   Hydropower is an important clean energy source in China. However, the construction and operation cycles of hydropower stations are long, and their long-term impact on the ecosystem is unclear. In arid areas, with their unique geographical location and dry climate, ecosystems often have limited self-regulation abilities, making restoring the local ecological environment after damage challenging. This study focuses on Longyangxia Hydropower Station, a representative hydropower station in an arid region of China, and uses Landsat series satellite data and land remote sensing products to monitor the ecological environment surrounding the hydropower station from 2000 to 2021. The study employs buffer zone and trend analyses to assess the impact on the ecological environment arounding the Hydropower. The results indicate the following: (1) The land use pattern around Longyangxia Hydropower Station did not change significantly from 2000 to 2021. However, the proportion of grasslands increased slightly, while that of other land use types decreased slightly. (2) During the same period, the wetland area around Longyangxia Hydropower Station increased significantly. (3) The vegetation in the surrounding area of Longyangxia Hydropower Station showed good growth over the past two decades, with an increase in the proportion of areas with high vegetation coverage. (4) The carbon sequestration capacity of vegetation in the vicinity of the hydropower station improved, and vegetation productivity gradually recovered as the growth rate of the wetland area decreased. Figures and Tables | References | Related Articles | Metrics

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Construction of the ecological network in the Aksu River Basin SUN Maosen,WANG Ranghui,NING Husen 2023, 40 (9):  1509-1516.  doi: 10.13866/j.azr.2023.09.14 Abstract ( 141 )   HTML ( 10 )   PDF (6490KB) ( 173 )   The Aksu River Basin exhibits a typical oasis-desert pattern and is a significant ecological barrier along the Belt and Road. Rivers are crucial to the stability and development of ecosystems in arid regions. In the 1980s, the ecological environment of the Aksu River Basin faced severe environmental problems. Several ecological restoration projects have been implemented since 1986 to address these issues, resulting in improvements to the ecological environment. In this study, five counties and cities within the Aksu River Basin were selected as the study area to establish an ecological safety network. This network, which is of great research value and significance, was constructed by identifying ecological source areas, building an ecological resistance surface, extracting ecological corridors, and recognizing ecological pinch points and ecological barrier points in the Aksu River Basin. To identify and extract the ecological source areas, a morphological spatial pattern analysis was employed. Based on the physical geography and climate characteristics of the region, seven factors were selected to build an ecological resistance surface. Using the ecological sources and resistance surface as a foundation, the ecological corridors within the basin were identified. Furthermore, the data from five periods (1980, 1990, 2000, 2010, and 2020) were compared and analyzed to reveal changes in the ecological safety network over time. Additionally, an ecological network optimization plan was developed by identifying ecological pinch points and obstacles within the basin as of 2020. The research findings indicated the following: (1) Over the 40-year period, ecological restoration, and afforestation projects positively impacted the ecological environment of the Aksu River Basin. The ecological source area increased by 6%, almost double its previous size. (2) Due to the process of urbanization and industrial development, the resistance value of the river basin generally increased slightly. Areas with high resistance values were evident around towns in the economically developed areas of Aksu City. (3) Ecological corridors were mainly concentrated in the central and northern parts of the basin, with six new corridors added during the study period, indicating a denser ecological network and a more stable ecosystem than before. (4) The ecological network included 12 pinch points and seven barrier points in 2020. Based on these points, the government could implement ecological restoration to improve the resilience of the ecological network and propose corresponding improvement measures for land cover types. This research can provide a reference for ecological network restoration, key area identification, and land space optimization along the Belt and Road against the background of dual carbon. Furthermore, this study provides new inspiration for green development in arid basins. Figures and Tables | References | Related Articles | Metrics

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Assessment of ecological protection benefits in the Huangshui River Basin based on ecological assets SUN Bingqing,DU Jiaqiang,MAO Jialin,ZHANG Jing,SHENG Zhilu,ZHANG Yangchengsi 2023, 40 (9):  1517-1526.  doi: 10.13866/j.azr.2023.09.15 Abstract ( 108 )   HTML ( 16 )   PDF (12423KB) ( 37 )   Ecological assets refer to ecological systems that provide benefits and services to human beings. Assessing changes in ecological assets can objectively reveal the effectiveness of ecological protection efforts. Situated in the transition area between the Qinghai-Tibet Plateau and the Loess Plateau, the Huangshui River Basin has a fragile and sensitive ecological environment. It also has the highest population density and socioeconomic intensity in the region, making it the key area for implementing ecological protection policies and projects. By calculating the stock and discharge of ecological assets in the Huangshui River Basin, we comprehensively analyze the spatiotemporal dynamic changes in ecological assets in the watershed, investigate the driving factors behind the gains and losses in ecological assets using the geographical detectors model, and explore the ecological protection benefits in combination with different ecological protection measures. The results are as follows: (1) The comprehensive index of ecological assets in the Huangshui River Basin in 2020 was 30.98, showing a distribution pattern of low ecological assets in the southeast plain and high ecological assets in the northwest mountains. From 2000 to 2020, the comprehensive index of ecological assets increased by 6.71%, indicating an overall improvement in the quality of ecological assets. (2) In 2020, the ecological asset flow value of the Huangshui River Basin was approximately 107.374 billion yuan, with the regulation service value accounting for 69.50%. Over the past 20 years, ecological assets have increased by 83.116 billion yuan, of which 57.123 billion yuan was attributed to regulating services. The regulation of grassland ecological resources primarily contributed to the flow value, which is also influenced by the stock quality of ecological assets. (3) There was a notable spatial difference in the driving influence of ecological asset profit and loss in the Huangshui River Basin. Socioeconomic factors (average contribution of 12.95%) impacted ecological asset profit and loss more than natural factors (average contribution of 10.54%). (4) Ecological assets in the Huangshui River Basin have shown steady improvement, and considerable success has been achieved in ecological protection and restoration. However, the region faces challenges due to the imbalance between natural background restrictions and economic development, leading to significant spatial differentiation in ecological assets and continued pressure on local ecological protection. This study is of great significance for understanding the ecological status of the Huangshui River Basin and guiding the protection of its ecological assets. Overall, the ecological assets of the Huangshui River Basin have improved steadily. Figures and Tables | References | Related Articles | Metrics

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Identification of priority areas for ecological compensation under soil and water conservation in Ningxia SHEN Cao,REN Zongping,LI Peng,WANG Kaibo,LU Kexin,REN Zhengyan,WEI Xiaoyan 2023, 40 (9):  1527-1536.  doi: 10.13866/j.azr.2023.09.16 Abstract ( 124 )   HTML ( 9 )   PDF (10617KB) ( 66 )   Identifying priority areas for ecological compensation under soil and water conservation is an important reference for establishing a suitable compensation system to support local ecological development. In this study, the Ningxia Hui Autonomous Region is taken as the study area, and the InVEST model is employed to evaluate three major soil and water conservation service functions: water connotation, soil conservation, and carbon storage. Their respective value amounts were assessed. Additionally, the ecological compensation priority and ecological vulnerability index of each district and county are considered to conduct a spatial identification of priority areas for ecological compensation for soil and water conservation in Ningxia. Research has shown that the value of soil and water conservation in Ningxia has steadily increased each decade from 2000 to 2020, reaching 247.89 billion yuan, 266.17 billion yuan, and 295.85 billion yuan, respectively. Geographically, the southern regions generally exhibit higher values, whereas the northern regions show lower values, with Jingyuan County, Guyuan City, and Jinfeng District, Yinchuan City, representing the highest, and lowest values, respectively. Over the years, the priority compensation areas for soil and water conservation have experienced relatively minor changes. These areas are mainly located in the southern regions, characterized by high ecological value but economic backwardness. The secondary priority areas for ecological compensation are located in the central and northern regions, characterized by low ecological value but high economic development. Compensating these priority areas can effectively improve the efficiency of ecological compensation, foster the regional ecological environment, and promote sustainable economic, and social development. Figures and Tables | References | Related Articles | Metrics