Table of Content

15 August 2024, Volume 41 Issue 8 Previous Issue   

Weather and Climate

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Spatiotemporal characteristics of different grades of precipitation in Yellow River Basin from 1960 to 2020 YUAN Zheng, ZHANG Zhigao, YAN Jin, LIU Jiayi, HU Zhuyu, WANG Yun, CAI Maotang 2024, 41 (8):  1259-1271.  doi: 10.13866/j.azr.2024.08.01 Abstract ( 84 )   HTML ( 15 )   PDF (14451KB) ( 160 )   The Yellow River Basin is an important ecologically fragile area in China. The clarification of the relationship between different levels of precipitation, precipitation days, and precipitation intensity in the basin is important to characterize the precipitation patterns in the basin. Using precipitation data collected from 96 meteorological stations in the Yellow River Basin from 1960 to 2020, the spatial and temporal variation characteristics of different grades of precipitation in the basin were analyzed using mathematical statistics and Pearson correlation analysis, and the contribution and impact of different grades of precipitation on the total precipitation were discussed. In the studied recent 61-year period, the annual precipitation and precipitation intensity in the Yellow River Basin followed increasing trends with rates of 0.008 mm·(10a)-1 and 0.12 mm·d-1·(10a)-1, respectively. The number of precipitation days followed a decreasing trend with a rate of -1.82 d·(10a)-1. The rainfall and days of light rain and moderate rain followed a downward trend; the amount and number of days of heavy rain, rainstorm, and heavy rainstorm followed an upward trend, and the precipitation intensity of each grade followed an increasing trend. Over the recent 61-year studied period, the highest occurrence rate of light rain was 84.32%, with the highest contribution rate from light rain (37.64%) followed by moderate rain (34.47%). The occurrence rate and contribution rate of light rain followed decreasing trends, whereas the occurrence rate and contribution rate of precipitation of heavy rain followed increasing trends. The areas with high values of light precipitation, light precipitation days, and light precipitation intensity were mainly concentrated in the southwest of the basin. As the precipitation level increased, the areas with high precipitation, precipitation days, and precipitation intensity were mainly concentrated in the southeast of the basin. Correlation analysis revealed that the annual precipitation of the Yellow River Basin was strongly affected by moderate and heavy rainfall, the annual precipitation days were strongly affected by the light rain days, and the annual precipitation intensity was strongly affected by the amount of heavy rain, rainstorm, and precipitation days. These findings can support ecological protection in the basin. Figures and Tables | References | Related Articles | Metrics

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Ideal numerical tests of topographic precipitation around the Helan Mountain under different wind field structures LI Chao, LONG Xiao, CAO Yiqing, HAN Zifei, WANG Hao, ZHENG Jingyuan 2024, 41 (8):  1272-1287.  doi: 10.13866/j.azr.2024.08.02 Abstract ( 32 )   HTML ( 4 )   PDF (25822KB) ( 25 )   Topographic precipitation is one of the main types of precipitation in northwest China. It is therefore of great significance to achieve a deeper understanding of the mechanism of topographic precipitation formation to improve forecasting ability. In this study, the vertical distribution structure of different types of wind fields was constructed based on the high-altitude environmental parameters during 20 heavy rains around the eastern foothills of Helan Mountain, and the em_hill2d_x module of WRF model was used to conduct ideal numerical experiments on the influence of different types of wind field on precipitation distribution. The results show that: (1) The dry air flow of two different types of wind fields (with/without wind shear) on the windward slope of the mountain range has an uplift effect of terrain on the windward slope air flow. The leeward slope fluctuation showed different characteristics; under the condition of single layer uniform flow, the leeward slope is mainly represented by a mountain wave propagating in the vertical direction. Under the wind field with low-level wind shear, the leeward side mainly reflects the characteristics of the dorsal wave, and the gravity wave has the characteristics of coexisting horizontal and vertical propagation. With the increase in low-level wind shear, the characteristics of the horizontal propagation of the dorsal wave become increasingly obvious. (2) The simulated precipitation under the condition of a single layer of uniform wet airflow is mainly located on the windward side, and the precipitation intensity is relatively weak on the leeward side under the influence of strong downhill wind. When the wind speed increases to more than 10 m·s-1, the large cloud water content area on the windward side converges to the top of the mountain, and the precipitation intensity increases significantly. In the presence of low-level wind shear flow moving over the mountains, the test result shows that both the windward and leeward side there is a strong rainfall center, with a deep convective system on the leeward slope, and the precipitation on both sides increases with the increase in wind speed. (3) The simulation results under the condition of low-altitude east wind and high-altitude west wind show that the appearance of high-altitude west wind strengthens the updraft on the windward slope and is not conducive to the transport of water vapor downstream; the precipitation on the leeward side is significantly weakened; the precipitation is more concentrated near the upper reaches of the mountain peak; and the intensity also increases to a certain extent. This is one of the main reasons for the significant difference in precipitation characteristics between the two sides of the Helan Mountain. Figures and Tables | References | Related Articles | Metrics

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Synergistic effects of sea surface temperature and sea ice on the anomalous characteristics of precipitation distribution during the flood season in Ningxia WANG Dai, LI Xin, ZHANG Wen, MA Yang, WANG Suyan, LI Jiayao 2024, 41 (8):  1288-1299.  doi: 10.13866/j.azr.2024.08.03 Abstract ( 35 )   HTML ( 6 )   PDF (9972KB) ( 46 )   There are significant climate differences between the north and south of Ningxia; however, the evolution characteristics and factors influencing precipitation spatial patterns closely related to ecology require more detailed and in-depth analysis. Using climate statistical diagnostic methods, this research examines precipitation data during the flood season for 20 meteorological stations in Ningxia, NCEP/NCAR atmospheric reanalysis, sea surface temperature and Arctic sea ice data from 1961 to 2022. An abnormal index for the north-south pattern of precipitation during the flood season in Ningxia was identified and explored the possible impact of the synergy of Pacific sea surface temperature and Arctic sea ice signals driving this anomaly. The results show that the characteristic components of the north-south reverse phase of precipitation during the flood season in Ningxia have significant interdecadal variations. The frequency of the typical “northern flood and southern drought” distribution patterns increased significantly in the recent interdecadal background compared with before 1991, the proportion of the north-south reverse phase distribution pattern increased, and the north-south difference become more obvious. The synergistic (consistent phase) and antagonistic (opposite phase) effects of key indicators of Pacific sea surface temperature (Isst) and Arctic sea ice (Iice) cause abnormal geopotential heights over the Ural Mountains, Lake Baikal, and the Okhotsk Sea, resulting in different impact paths of cold air and positions of water vapor transport. When Isst and Iice are both positive, Ningxia is prone to the distribution pattern of “southern flooding and northern drought” during the flood season, characterized mainly by more precipitation in the southern region, less in the northern region, and more in the southern region than in the northern region. When Isst is positive and Iice is negative, the “northern flooding and southern drought” distribution pattern is likely to occur, especially when the northern region has more precipitation and the southern region has less. When Isst and Iice are both negative, the “northern flooding and southern drought” distribution pattern was likely to occur, mainly because of more precipitation in the northern region, less precipitation in the southern region, and less precipitation in the northern region compared with the southern region. When Isst is negative and Iice is positive, this was mainly due to the precipitation in the southern and northern regions being lower. Figures and Tables | References | Related Articles | Metrics

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Spatial-temporal variations and trends in the human body comfort index in the Qaidam Basin, China, during 1979-2020 ZHANG Qunhui, CHANG Liang, GU Xiaofan, WANG Qian, MA Maonan, LI Xiaodeng, DUAN Rui, YOU Xiangzhi 2024, 41 (8):  1300-1308.  doi: 10.13866/j.azr.2024.08.04 Abstract ( 41 )   HTML ( 2 )   PDF (8230KB) ( 36 )   Research on climate comfort assessment in the Qaidam Basin is of great significance for the environment, the development of liveable climate resources, and the construction of ecology and civilization. This study utilized surface meteorological datasets with a long time series from 1979-2020, as well as the index of human body comfort, to analyze the spatial-temporal changes in human comfort at the interannual and seasonal scales in the Qaidam Basin. The results indicated that (1) the human comfort level in the entire basin increased over the years and in different seasons. Most areas were cold and uncomfortable, with the exception of some areas in the summer plains at a sufficient comfort level. (2) the change in the index of human body comfort had the strongest correlation with the change in air temperature in the entire basin, with a correlation coefficient >0.9, followed by wind speed and humidity. The correlation was weaker in the mountainous areas than in the plains. (3) through comprehensive analysis of trends and the Hurst index, it was observed that the air temperature and specific humidity continued to elevate with a strong persistence, while wind speed showed the opposite trend; except for the weak persistence in autumn in some mountainous areas, the index of human body comfort showed a conspicuous and continuous increasing trend in other seasons both in the mountains and plains. This study can provide some reference for the study of climate suitability in the Qaidam Basin and other alpine regions. Figures and Tables | References | Related Articles | Metrics

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Paleoclimatic evolution and driving mechanisms in arid areas of inland Asia during the Middle Miocene Climatic Optimum in the context of global climate warming LYU Zhuangzhuang, QIAO Qingqing, DONG Sunyi, WANG Dong 2024, 41 (8):  1309-1322.  doi: 10.13866/j.azr.2024.08.05 Abstract ( 30 )   HTML ( 2 )   PDF (13079KB) ( 35 )   The Mid-Miocene Climatic Optimum, a notable global warming event that occurred during cooling in the Cenozoic period, is being considered as a potential analog for future climate conditions. Arid areas of inland Asia are representative of mid-latitude arid zones throughout the globe, and their desertification exerts the strongest and most direct impacts on human habitation environments. Against the backdrop of global warming, which is compounded by human activities, these arid zones become increasingly fragile, with their expansion or alteration directly impacting human survival and sustainable development. The exploration of the climatic evolutionary history of the arid areas of inland Asia during the Middle Miocene under a global warming scenario can provide crucial insights for the projection of climate changes in arid regions under future warming patterns. This study reviewed the existing research on the paleoclimatic evolution during the Middle Miocene in typical basins of arid areas of inland Asia. Through a comprehensive analysis of various climatic proxies, including environmental magnetic parameters, pollen, and isotopes, the findings indicate the prevailing trend is toward increased humidity in most regions during this period, although there were variations in the timing of humidification and some areas remained arid. However, significant controversy remains regarding the primary regulator of the formation of the Mid-Miocene Climatic Optimum: some scholars argue that eruptions of Columbia basalt are the primary factor; others propose that tectonic activity is the main driver. To address the aforementioned controversies, obtaining higher-resolution records with precise age control is essential to determine the onset response time of the Mid-Miocene warming event. Through the accurate interpretation of climatic proxies, especially pollen, which directly and sensitively responds to paleoclimatic changes, as well as environmental magnetic parameters and geochemical ratios encapsulating paleoenvironmental information, the various factors influencing climate change can be clarified to reveal the driving mechanisms behind the climatic evolution during the Mid-Miocene Climatic Optimum in arid areas of inland Asia. Figures and Tables | References | Related Articles | Metrics

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Analysis of carbon component pollution characteristics and sources of PM2.5 in Urumqi City WEI Jiang, SONG Dandan, ZHAO Lili, ZHAO Caixin, WANG Lingxi 2024, 41 (8):  1323-1330.  doi: 10.13866/j.azr.2024.08.06 Abstract ( 30 )   HTML ( 3 )   PDF (5238KB) ( 17 )   To investigate the concentration of PM2.5, pollution characteristics, and sources of carbon components in the urban area of Urumqi from July 3, 2023, to December 31, 2023, air samples were collected and monitoring and analysis were performed in accordance with experimental procedures. The average concentration of PM2.5 in Urumqi is 20.1±8.1 µg·m-3, with average concentrations of OC and EC of 3.2±1.0 and 0.6±0.2 µg·m-3, respectively, and a trend for higher concentrations during the heating season than the nonheating season. Good correlations between OC and EC were observed in various time periods, suggesting a similar source for OC and EC. The estimated average total carbon aerosol concentration is 7.52±3.66 µg·m-3, accounting for approximately 16% of the PM2.5 concentration, and the concentration of secondary organic carbon (SOC) is 2.11±1.43 µg·m-3, with an SOC/OC ratio of 47.47%±12.69%, indicating that secondary organic carbon (SOC) accounts for nearly 50% of the OC in Urumqi’s atmosphere. Principal component analysis revealed that the main sources of carbon components in PM2.5 are coal combustion emissions and vehicular exhaust. Overall, severe atmospheric pollution persists during the heating season. Figures and Tables | References | Related Articles | Metrics

Land and Water Resources

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Application of airborne LiDAR with fuzzy inference system in soil erosion monitoring on the Loess Plateau QIU Chunxia, LIU Xiaohong, LI Dou, ZHANG Jiamiao, LI Pengfei 2024, 41 (8):  1331-1342.  doi: 10.13866/j.azr.2024.08.07 Abstract ( 37 )   HTML ( 16 )   PDF (15389KB) ( 60 )   The Loess Plateau is widely recognized as one of the most severely eroded regions, both within China and globally. Because of the limitations in monitoring technology, the study of soil erosion has primarily focused on areas of small-scale flow; indeed, large-scale erosion studies and field observations remain relatively scarce. The introduction of airborne LiDAR technology has opened new possibilities for high-precision, large-scale soil erosion research. However, LiDAR is impacted by complex terrain and introduces height uncertainty, which limits its capacity to effectively monitor soil erosion. This study analyzes the typical small watershed of Qiaogou in the hilly gully area of the Loess Plateau in China. To overcome the aforementioned challenges, LiDAR measurements were combined with a fuzzy inference system (FIS) to quantitatively analyze the spatial distribution of the DoD uncertainty and investigate the spatial distribution characteristics of soil erosion and sedimentation within the small watershed. The results show that: (1) Terrain shape and point cloud density greatly influence the DEM error generated by interpolation, with significantly smaller DoD uncertainty in flat terrain regions than in steep terrain regions; (2) By integrating known error sources into a stable error model, the FIS algorithm reduces subjective intervention and human error, avoiding error estimation on complex DEM surfaces and improving the accuracy of calculation results; (3) The sediment yield volume of the hillslope area is 9.21 m³, comprising 15.89% of the sediment yield volume of the slope gully system. Erosion in the gully slope area is severe, with a sediment yield volume of 48.76 m³, comprising 84.11% of the sediment yield volume of the slope gully system; hence, it is the main component of the sediment yield of the slope gully system. The trench bed area is primarily sedimentary. Ridge slopes and gully slopes have a larger contribution to sediment production, whereas the bottom of the gully is mainly a sediment-producing area. These research findings provide a new perspective on the development of soil erosion monitoring technology in the small watersheds of the Loess Plateau and offer a theoretical basis and reference for the implementation of effective soil and water conservation measures. Figures and Tables | References | Related Articles | Metrics

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Soil moisture variation characteristics of alpine meadow with different cover types in the Three-River Source Region WAN Jiayi, SHI Jiayu, ZHANG Huamin, LI Lanhui, DING Mingjun 2024, 41 (8):  1343-1353.  doi: 10.13866/j.azr.2024.08.08 Abstract ( 33 )   HTML ( 3 )   PDF (9519KB) ( 49 )   Soil moisture is the material foundation for plant growth and reproduction; therefore, understanding its dynamic properties is critical for local water management and vegetation restoration. The study area of this research was the alpine meadows in the Three-River Source Region, and the study combined field surveys and laboratory experiments to analyze the annual, seasonal, and daily dynamic characteristics of soil moisture in alpine meadows under different cover types and explore the influence of vegetation and soil factors on soil moisture changes. The findings revealed that: (1) In 2022, when there was less rainfall and temperatures were higher, the soil liquid water content in different areas decreased by 1% to 18% compared with previous years; the soil unfrozen water content was higher in summer and fall than in winter and spring; and the highest monthly average water content of various sites occurred in October (0.495 m3·m-3) and the lowest value was in January (0.038 m3·m-3); the daily variations in the soil liquid water content in March and December were larger, ranging from 0.11 to 0.20 m3·m-3 and 0.07 to 0.16 m3·m-3, respectively. (2) Mildly and highly degraded alpine meadows (YG4) and native alpine meadows (YG5) have greater vegetation cover and lower bulk density, resulting in greater soil water content and less variance. (3) Artificial grassland did not promote soil water retention owing to its high water consumption, single species, and low soil fertility. The results of the study can provide a reference for the restoration and management of alpine meadow ecosystem in the Three-River Source Region. Figures and Tables | References | Related Articles | Metrics

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Stoichiometry of carbon, nitrogen, and phosphorus in the litter and soil of Pinus sylvestris var. mongolica in the Hulunbuir Sandy Land DONG Peng, REN Yue, GAO Guanglei, DING Guodong, ZHANG Ying 2024, 41 (8):  1354-1363.  doi: 10.13866/j.azr.2024.08.09 Abstract ( 33 )   HTML ( 5 )   PDF (3456KB) ( 20 )   To reveal the characteristics of litter and soil C, N, and P stoichiometry and their main driving factors in the Hulunbuir Sandy Land. Different ages of Pinus sylvestris var. mongolica plantation forests and natural forests (medium-mature, near-mature, and mature forests) were used as research subjects to analyze the characteristics of litter and soil C, N, and P stoichiometry and their correlation with soil factors was explored. (1) The degree of decomposition significantly affected litter C, N, P, and the C:N ratio (P<0.05) and the soil layer significantly affected soil N and C:N and C:P ratios (P<0.05); however, the stand age of the forest and its interactions with the degree of decomposition and soil layer did not have a significant effect on litter and soil C, N, and P stoichiometric characteristics (P>0.05). There were significant differences (P<0.05) between natural and plantation forests in litter and soil relating to C and N contents and C:P and N:P ratios. (2) Litter C content was significantly and positively correlated with litter N and P content (P<0.05), and the litter C:P ratio was significantly and positively correlated with the C:N ratio (P<0.05); the soil C:P ratio was significantly and positively correlated with the soil N:P and C:N ratios (P<0.05). (3) The C, N, and P stoichiometric characteristics of litter were mainly significantly affected by pH, phosphatase, and urease (P<0.05), and the soil C, N and P stoichiometric characteristics were mainly significantly affected by pH, phosphatase, and convertase (P<0.05). The growth of P. sylvestris var. mongolica forest in the Hulunbuir Sandy Land may be limited by nitrogen, whereas the decomposition of litter may be limited by phosphorus; the main drivers of litter and soil C, N, and P stoichiometric characteristics were pH and phosphatase, respectively. This improved information is of great significance for guiding the management of P. sylvestris var. mongolica forests. Figures and Tables | References | Related Articles | Metrics

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Soil physical and mechanical properties of lightly grazed and prohibited grasslands: A case study of Xiazangtan landslide area ZHANG Peihao, XING Guangyan, ZHAO Jimei, LIU Changyi, HU Xiasong 2024, 41 (8):  1364-1372.  doi: 10.13866/j.azr.2024.08.10 Abstract ( 26 )   HTML ( 0 )   PDF (2619KB) ( 16 )   To determine the effects of light grazing and grazing prohibition on the physical and mechanical properties of grassland soil in the landslide distribution area of the upper reaches of the Yellow River, the Xiazangtan landslide distribution area in the upper reaches of the Yellow River was selected as the study area. The plant growth and physical and mechanical properties of soil in different slope directions of lightly grazed grassland and grazing-prohibited grassland were compared and analyzed by conducting a field investigation, sampling, and testing the indoor soil physical and mechanical properties. The effects of light grazing and grazing prohibition on plant growth and soil physical and mechanical properties of slope in landslide distribution area were discussed. The results showed that the number of plant species, average cover, and average plant height in the grazing-prohibited grassland were higher than that in the lightly grazed grassland, and increased by 65.1%, 62.8%, and 13.6%, respectively. With the increase in soil depth, the soil density of the two types of grassland showed a trend of decreasing first and then increasing, soil water content and root dry weight density followed a decreasing trend, soil cohesion showed a “V”-type change, and the soil physical and mechanical properties of the same type of grassland with different soil depth were significantly different (P<0.05). The soil density, soil moisture content, root dry weight density, and soil cohesion of the two types of grassland followed an increasing trend from the top to the bottom of the slope. In the same slope direction, the soil density of lightly grazed grassland was significantly higher than that of grazing-prohibited grassland (P<0.05), whereas the soil moisture content, root dry weight density, and soil cohesion of grazing-prohibited grassland were significantly higher than those of lightly grazed grassland (P<0.05). The soil internal friction angle did not show a significant pattern of change in response to the soil depth and slope position, and there was no significant difference between the two types of grassland in the same slope direction. Soil cohesion was positively correlated with soil moisture content and soil density and soil cohesion was significant positively correlated with root dry weight density (P<0.05) in two types of grasslands. Therefore, grazing prohibition is beneficial for the restoration of degraded grasslands, the improvement of plant community structure, and inhibits soil erosion. The results of this study provide a theoretical basis and practical guidance for the effective prevention and control of secondary geological disasters, such as soil erosion and shallow landslides, on riverbank slopes in the study area. Figures and Tables | References | Related Articles | Metrics

Plant Ecology

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Changes in vegetation cover and driving factors in the Yellow River Basin from 2001 to 2021 WU Siyuan, HAO Lina 2024, 41 (8):  1373-1384.  doi: 10.13866/j.azr.2024.08.11 Abstract ( 37 )   HTML ( 2 )   PDF (18910KB) ( 61 )   As an important ecological barrier and economic corridor in China, the study of the Yellow River Basin reveals the response mechanism of vegetation cover change, which is conducive to promoting the coordinated development of ecology, economy, and society. Based on MOD13A3 climate and economic data, this paper uses trend analysis and correlation analysis to determine the characteristics of vegetation cover change in the Yellow River Basin from 2001 to 2021, and explores the mechanisms of impact of climate and human activities on vegetation. The results show that: (1) From 2001 to 2021, the rate of vegetation cover increase in the study area was 0.35%·a-1, and the vegetation cover in 81.33% of the area followed an increasing trend. (2) On the time scale, the NDVI response to climate and human activities in the Yellow River Basin lags; on the spatial scale, NDVI is positively correlated with precipitation and temperature. NDVI’s response to precipitation is concentrated in the 200 mm precipitation line, and its response to temperature is distributed in the plateau subarctic zone and the middle temperate zone. The impact of human economic activities on NDVI was a predominantly positive correlation, among which NDVI was positively correlated with the primary industry and negatively correlated with the secondary industry, accounting for 51.45% and 7.47% of the total area, respectively. (3) The vegetation change in the Yellow River Basin is affected by both climate and human activities. The area affected by human economic activity factors comprised 55.25% of the total area, which was a majority, indicating that human activities, such as economic development, have a significant impact on the growth and distribution of vegetation that exceeds the effects of precipitation and temperature changes. Figures and Tables | References | Related Articles | Metrics

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Characteristics of vegetation cover changes in the upper reaches of the Yellow River Basin and the influencing factors ZHANG Hongwei, BIE Qiang, SHI Ying, SU Xiaojie, LI Xinzhang 2024, 41 (8):  1385-1394.  doi: 10.13866/j.azr.2024.08.12 Abstract ( 44 )   HTML ( 1 )   PDF (10683KB) ( 46 )   Vegetation coverage provides a good reflection of the ecological status of the watershed, and remote sensing technology is important for the large-scale, efficient, and accurate monitoring of changes in vegetation coverage. This study examined the temporal and spatial variation characteristics of vegetation coverage in the upper reaches of the Yellow River Basin from 2001 to 2020, using the Hurst index and Cv coefficient to test persistence and stability. The effects of climate, topography, and population on changes in vegetation coverage were analyzed. The results showed that the vegetation coverage increased from northeast to southwest, with an increasing trend in 69.25% of the areas. Stable areas accounted for 73.79% of the total area, and areas of strong sustainability accounted for 66.49%. (2) Of the total area, 75.63% was positively correlated with precipitation and 39.28% was positively correlated with temperature. (3) As elevation increased, vegetation coverage first increased and then decreased; coverage was positively correlated with slope but not significantly related to aspect. (4) The vegetation coverage was highest when the population density was 65-85 individuals·km-2 and the GDP was 27000-37000 yuan·km-2, indicating that human activities promoted changes in the vegetation cover in the upper reaches of the Yellow River Basin. The results of this study provide a scientific reference to support the high-quality ecological development of the upper reaches of the Yellow River Basin. Figures and Tables | References | Related Articles | Metrics

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Changes in NDVI and its multiscale spatiotemporal responses to precipitation in the Mu Us Desert SHI Tianyi, ZHANG Mengmeng, PU Yang, LIU Shuoyuan 2024, 41 (8):  1395-1404.  doi: 10.13866/j.azr.2024.08.13 Abstract ( 26 )   HTML ( 0 )   PDF (19266KB) ( 27 )   The Mu Us Desert possesses a delicate ecological environment. It is therefore of utmost importance to understand the correlation between sand-fixing vegetation and precipitation to achieve effective ecological restoration and implement the concept of “water-oriented greening” in the desert. This study examined the fluctuation patterns in vegetation within the Mu Us Desert from 2000 to 2018, as well as its reaction to delayed and cumulative precipitation effects. Our findings revealed significant trends in the annual and seasonal average NDVI of the study area from 2000 to 2018 (P<0.01). However, the spatial distribution of these trends exhibited substantial variation. Notably, the region with a significant increase in summer NDVI accounted for 83.2% of the total area, whereas the region with a significant increase in annual NDVI accounted for only 34.15% of the total area. Moreover, the annual and monthly variations in vegetation NDVI showed no significant time lag in response to precipitation, but a significant cumulative effect was observed. Approximately 38.58% of the study region exhibited a cumulative response of NDVI to precipitation lasting between one and two years, which was mostly concentrated in areas with lower annual precipitation and negligible changes in annual NDVI. Finally, the spatial and temporal distribution of the correlation coefficient between seasonal NDVI and cumulative monthly precipitation exhibited pronounced differences. The response time and percentage of NDVI to precipitation varied across seasons, with a range of 2-3 months (19.25%) for spring, 4 months (73.58%) for summer, and either 1 month (27.22%) or 3 months (34.91%) for autumn. This study revealed the absence of significant temporal delays in the vegetation response to precipitation in the Mu Us Desert. Additionally, it revealed that the cumulative effects varied significantly across different spatiotemporal scales. Consequently, the findings of this study serve as a foundation for optimizing ecological restoration programs involving artificial vegetation, as well as implementing the “water-based greening” approach. Figures and Tables | References | Related Articles | Metrics

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Species diversity and distribution patterns of threatened vascular plants in Kyrgyzstan SU Yuqi, MA Suliya, LI Yufan, WEI Qiuyu, WANG Hongfeng, LI Wenjun 2024, 41 (8):  1405-1412.  doi: 10.13866/j.azr.2024.08.14 Abstract ( 34 )   HTML ( 4 )   PDF (2384KB) ( 34 )   In order to understand the current situation of threatened vascular plant resources in Kyrgyzstan, this paper took threatened vascular plants in Kyrgyzstan as the research object, and used ArcGIS software to study their species richness distribution pattern combined with existing protected area data, and analyzed their family and genus composition, threat grade, life forms, and plant resource diversity. The results showed that there were 86 species of threatened plants in 27 families, 61 genera (including subspecific grades, the same below). Angiosperms dominate, monotypic families and monotypic genera are the main components of families. In terms of threat level, there are 12 species of Critically Endangered species (CR), 22 species of Endangered species (EN), and 52 species of Vulnerable species (VU), and human activities are the most important threat factors. The life types were divided into 64 species of perennial herbs, 9 species of trees, 7 species of shrubs, 6 species of subshrubs and 1 species of annual herbs and vines. The distribution of threatened plants is not uniform at the phytogeographic area scale, and they are concentrated in the west and southwest of Gilji, and the geographical protection area of plants with high species richness is small. On this basis, some suggestions for the protection of threatened vascular plants in Kyrgyzstan were put forward in order to provide reference for the conservation of plant diversity in the study area. Figures and Tables | References | Related Articles | Metrics

Ecology and Environment

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Grain size characteristics and sand source analysis of three aeolian landforms in the lower reaches of the Qira River floodplain LI Xinxin, MAO Donglei, LAI Fengbing, XUE Jie, HE Qiangqiang, MA Yujiao 2024, 41 (8):  1413-1422.  doi: 10.13866/j.azr.2024.08.15 Abstract ( 39 )   HTML ( 1 )   PDF (10046KB) ( 50 )   The grain size characteristics of sediments provide extensive information on environmental change, which is of great importance for the study of desert management and for preventing desertification. The grain size characteristics and sedimentary environment stability of different aeolian landforms were studied using grain size analysis, the grain size-standard deviation method, and Sahu genetic discrimination. The results show that: (1) The surface sediments of barcrescent dune s, scrub dunes, and low bare flat sand are dominated by medium sand, fine sand, and extremely fine sand. The surface sediments were coarsest in barcrescent dunes and smallest in scrub dunes, with average grain sizes of 270.42 µm and 95.60 µm, respectively. (2) The sediment sorting of the three geomorphic types was poor, with proportions of 74.47%, 90.47% and 66.7%, respectively. The surface sediments of barcrescent dunes have a negatively skewed distribution and medium peak state, whereas the surface sediments of scrub dunes and low bare flat sand have a symmetrical distribution, medium peak state, and narrow peak state. (3) The environmentally sensitive components of the three different aeolian landforms were concentrated in the size range from 22.4-399 µm, which is more sensitive to climate change and therefore more able to reflect changes in the sedimentary environment, indicating that the aeolian sedimentary environment is mainly dominated by aeolian sedimentary environment. (4) The surface sediments of scrub dunes were found wholly in the aeolian environment, and the surface sediments of barchan dunes and low bare flat sand were found in both aeolian and fluvial environments. Figures and Tables | References | Related Articles | Metrics

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The impact of photovoltaic power plant operation on local ecological environments in arid areas WANG Yiwen, MA Yaoyao, SHI Peijun, ZHANG Gangfeng 2024, 41 (8):  1423-1433.  doi: 10.13866/j.azr.2024.08.16 Abstract ( 89 )   HTML ( 5 )   PDF (14002KB) ( 52 )   The emerging use of photovoltaic power is aligned with the progression of the energy industry. In China, photovoltaic power plants are widely constructed in the arid areas of the northwest. The ecological environment in the arid areas of the northwest is relatively fragile, and the potential environmental impacts of photovoltaic power plants during operation are not yet fully revealed. In this research, a comprehensive analysis of the impact of photovoltaic power plant construction on the local atmosphere, soil, vegetation factors, and other elements of the ecological environment was performed on the research area of Tala photovoltaic power station in Gonghe County, Qinghai Province (the world’s largest photovoltaic industrial park). The analysis combined observational data on ecological indicators of the areas adjacent to photovoltaic panels and the open space for photovoltaic power plants from March 2023 to February 2024 with remote sensing data from 2000 to 2020. The results show that the construction of photovoltaic panels has the effects of warming, humidifying, increasing temperature extremes, and wind speed reducing on the local atmosphere. The average humidification was 3.87%, the wind speed was reduced by 0.25 m·s-1, and the temperature extreme value changed by 1.72 ℃. The construction of photovoltaic panels also caused the effects of warming, reducing moisture, and reducing soil CO2 content in the local soil, with an average temperature increase of 1.83 ℃, a decrease in humidity of 4.81%, and a reduction in soil CO2 by 156.94 ppm. Finally, the construction of photovoltaic power plants promoted an increase in vegetation coverage and growth in the area, and had a positive promoting effect on the carbon fixation capacity of the ecosystem. The average growth rate of NDVI in the study area was faster than that in Hainan Prefecture; the difference was 0.001 kg C·m-2·a-1. The study shows that the operation of photovoltaic power plants can improve the environment in arid areas, by altering air humidification, soil warming, wind prevention, and sand fixation, promoting vegetation growth, and continuing to promote the local ecological environment. Figures and Tables | References | Related Articles | Metrics