Table of Content

15 May 2024, Volume 41 Issue 5 Previous Issue    Next Issue

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Contents 2024, 41 (5):  0-0.  Abstract ( 79 )   PDF (526038KB) ( 92 )   Related Articles | Metrics

Weather and Climate

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Spatial and temporal variation of drought in Northwest China based on CMIP6 model SHAN Jian'an, ZHU Rui, YIN Zhenliang, YANG Huaqing, ZHANG Wei, FANG Chunshuang 2024, 41 (5):  717-729.  doi: 10.13866/j.azr.2024.05.01 Abstract ( 216 )   HTML ( 27 )   PDF (16569KB) ( 113 )   Based on data from 152 meteorological stations in Northwest China and 16 climate models of CMIP6, the CMIP6 model data were bias-corrected using the RoMBC method. The Standardized Precipitation Evapotranspiration Index (SPEI) was then constructed to analyze the spatial and temporal distribution and variation of drought in Northwest China under the historical and future scenarios (SSP1-2.6, SSP2-4.5, SSP3-7.0, SSP5-8.5). The results are as follows: (1) Under the historical scenario, the northwest area experienced a notable increase in both the temperature and precipitation. The temperature and precipitation have been rising at a rate of 0.15-0.74 ℃ and 2.71-14.83 mm per decade, respectively, and the same is expected for future scenarios. (2) From 1975 to 2014, the annual and seasonal SPEI in Northwest China decreased overall. The maximum decline rate in spring was 0.19 per decade. Droughts in most areas were increasingly intense throughout the year, particularly in spring and winter. In terms of drought frequency in Northwest China, mild and moderate droughts appeared more than severe and extreme droughts, and this type of natural disaster was more frequent in the east of the country than in the west. (3) From 2020 to 2100, Northwest China is likely to suffer from droughts, but there are no distinct drought characteristics identified in the research under the SSP1-2.6 scenario. The northwest region is expected to experience an increase in the number of droughts, trends in drought, and drought frequency under the other three scenarios. The most severe drought conditions were observed under the SSP5-8.5 scenario. This study provides insights into the spatial and temporal development of drought in Northwest China using meteorological and model data. The findings can serve as a basis for drought risk assessment, scientific water resources management, and agricultural production in the region. Figures and Tables | References | Related Articles | Metrics

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Properties of aerosol scattering and its influencing factors in semiarid areas of Inner Mongolia YE Hu, PEI Hao, JIANG Yanfeng, NA Qing, ZHANG Liwei 2024, 41 (5):  730-741.  doi: 10.13866/j.azr.2024.05.02 Abstract ( 156 )   HTML ( 6 )   PDF (10325KB) ( 58 )   From observational data of scattering coefficients, the mass concentrations of aerosols and pollutants, and meteorological elements, collected from July 9, 2020 to July 8, 2023 in Xilinhot, the characteristics of aerosol scattering coefficients—including the variation over time, probability density distribution, and correlation with different types of aerosols and meteorological impact factors—are studied. Consequently, the scattering coefficient levels are classified. The results show that: (1) the overall level of aerosol scattering is relatively low, but the transport of dust aerosol in spring and the high frequency of temperature inversions in winter and at night may increase aerosol scattering. (2) The smaller the aerosol, the higher the correlation between aerosols and scattering coefficients, with the correlation coefficients following the order BC>PM2.5>PM10, although seasonal differences are observed. In addition, NO2 is an important factor in increasing scattering in autumn, whereas SO2 contributes to scattering in summer, autumn, and winter. (3) The increases in correlation coefficients are considered as the contribution rates of current meteorological factors to scattering coefficients, with contribution rates of between 1% and 2%. Figures and Tables | References | Related Articles | Metrics

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Spatial and temporal evolution characteristics of different grades of cold days in Qinghai Province CAI Yuqin, QI Donglin, WANG Liefu, LI Haifeng, ZHANG Deqin 2024, 41 (5):  742-752.  doi: 10.13866/j.azr.2024.05.03 Abstract ( 139 )   HTML ( 22 )   PDF (8369KB) ( 77 )   Based on the daily minimum temperature measured at 42 meteorological stations in Qinghai Province from 1961 to 2019, the spatial and temporal evolution of different grades of cold days (extreme cold, extremely cold, severe cold, major cold, minor cold, light cold, slightly cold, cool) were analyzed. The results showed that: (1) From 1961 to 2019, the number of cold days in Qinghai Province gradually increased with decreasing levels, mainly dominated by slightly cold days. The total number of cold days showed an overall decreasing trend, with a significant rapid decrease occurring in 1995. The decrease in total cold days was mainly caused by the reduction in extremely cold days. After the climate abrupt change in 1997, the trends of severe cold, major cold, minor cold, light cold, slightly cold, and total cold days decreased, while the trend of extremely cold days increased. The trends of extreme cold and cool days decreased and increased respectively, with a distribution roughly equal. (2) Qinghai Province exhibits significant spatial differences in cold days, with the total number of cold days gradually increasing with altitude, and the trends of higher-level cold days are more pronounced. As the level of coldness decreases, the trends of increase and decrease develop towards lower latitudes and areas with relatively lower altitudes. (3) The numbers of extreme cold, extremely cold, severe cold, light cold, slightly cold, and total cold days gradually decrease with increasing annual mean temperature, while the numbers of major cold, minor cold, and cool days gradually increase with increasing annual mean temperature. (4) Except for severe cold days, the numbers of other levels of cold days in Qinghai Province show persistence, and the downward trend will continue in the future, but the strength of persistence varies. Figures and Tables | References | Related Articles | Metrics

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Analysis of precipitation characteristics in the Xiagou reservoir watershed in Yiwu County, Hami City, during the rainy season YANG Xia, JIANG Yuan'an, ZHANG Linmei, LI Penglun, XIAO Jun'an 2024, 41 (5):  753-764.  doi: 10.13866/j.azr.2024.05.04 Abstract ( 125 )   HTML ( 11 )   PDF (12983KB) ( 133 )   Reservoirs play a pivotal role in regional economic development and societal well-being. In recent years, Xinjiang has experienced frequent extreme precipitation events, which pose significant challenges to reservoir safety. However, research on precipitation characteristics specific to Xinjiang’s reservoirs remains limited, preventing scientific guidance for water resource utilization and reservoir management. Using daily precipitation data from 1961 to 2022 and hourly precipitation data from 2009 to 2022 in the Xiagou reservoir watershed of Yiwu County, Hami City, this study analyzes long-term variations at different time scales and precipitation levels. The findings indicate following points: (1) During the rainy season from 1961 to 2022, the average precipitation in the Xiagou reservoir catchment area showed a weak increase, and the number of days with discontinuous precipitation enhanced significantly. The total number of precipitation days and the maximum number of continuous precipitation days reduced evidently. Together, these trends may lead to further enhancement of the precipitation intensity in the region. (2) The rainy season is mainly characterized by light rainfall; however, over the past 62 years, the number of light and moderate rain days has declined, unlike heavy and torrential rain days. The highest proportion of rainstorms to total rainfall during the rainy season was approximately 50.0%, which was the main reason for the increase in precipitation during the rainy season in the Xiagou reservoir catchment area. (3) Daily precipitation values displayed a rising pattern as the precipitation intensity strengthened. For instance, high values for light, moderate, heavy, and torrential rain occurred in the afternoon, midday, morning, and early morning, respectively. Except for torrential rain, high values for other precipitation levels were predominantly observed during the daytime. The daily variation curves for the average precipitation intensity exhibit multiple peaks with remarkable variations. The relationship between cumulative precipitation frequency and amount was more closely associated with light and moderate rain than with precipitation intensity. Conversely, the relationship between average precipitation intensity and cumulative precipitation amount was more closely related to heavy and torrential rain than to cumulative precipitation frequency. Figures and Tables | References | Related Articles | Metrics

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Simulation of land surface temperature in complex mountainous terrain and the influence of environmental factors: A case study in Daqingshan, Inner Mongolia ZHAO Lichao, ZHANG Chengfu, HE Shuai, MIAO Lin, FENG Shuang, PAN Sihan 2024, 41 (5):  765-775.  doi: 10.13866/j.azr.2024.05.05 Abstract ( 116 )   HTML ( 6 )   PDF (10349KB) ( 59 )   This study aimed to spatially and temporally characterize not only land surface temperature (LST) in the complex mountainous terrain of Daqingshan, Inner Mongolia but also the environmental factors affecting it. We used the Weather Research and Forecasting Mode (WRF) used to obtain LST data with high temporal and spatial resolution and analyze the variation of mountain influencing factors. The accuracy of the WRF simulated LST (WRF LST) was verified by the observation values of meteorological stations and MODIS LST values, and the relationship between LST and environmental factors was analyzed by the method of comprehensive impact factor analysis and the method of single impact factor analysis. The comprehensive impact factor analysis is based on regional WRF LST and regional environmental factors. Single impact factor analysis achieves the relationship between WRF LST and single environmental factors by fixing other environmental factors. The results revealed that the correlation coefficients between the simulated and observed values were >0.97 (P<0.001) and the spatial correlation with MODIS LST was 0.73 (P<0.05), indicating that WRF has good practicability in mountainous areas. After comprehensive impact factor analysis, it was found the annual WRF LST had the greatest correlation with elevation (R>0.97), followed by temperature at 2 m and water/air mixing ratio at 2 m (R>0.8), vegetation coverage and slope (R>0.3), and other factors. By single impact factor analysis, LST decrease rate with elevation was 0.83 K·(100m)-1, 0.79 K·(100m)-1, 0.80 K·(100m)-1 and 0.32 K·(100m)-1 in spring, summer, autumn and winter, and it increased by -0.05 K, 0.17 K, -0.14 K, and 0.02 K for every 10° increase in slope in spring, summer fall winter, respectively. LST also increased for every 10% increase in vegetation cover by 0.31 K, 1.41 K in summer and winter, and was not correlated with fall. The slope direction and average LST for the four seasons were south>southwest>southeast>west>east>northwest>northeast>north. The 2 m water-air mixing ratio increased logarithmically with LST, while the 2 m air temperature increased exponentially with LST. This study demonstrated that the WRF model can be used to simulate the spatial and temporal distribution of LST in mountainous terrain and analyze the LST relationship in complex mountain environments. Figures and Tables | References | Related Articles | Metrics

Land and Water Resources

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Spatiotemporal evolution of water yield in the lower Malian River Basin GAO Yayu, SONG Yu, ZHAO Tinghong, GAO Jinfang, HE Wenbo, LI Zexia 2024, 41 (5):  776-787.  doi: 10.13866/j.azr.2024.05.06 Abstract ( 125 )   HTML ( 13 )   PDF (17061KB) ( 67 )   This study examines water yield patterns in the lower reaches of the Malian River Basin, which are typical loess plateau gully areas in eastern Gansu Province, China. These areas are crucial for regional ecosystem health and understanding the temporal and spatial characteristics and response of water yield considering climate and land-use changes. Employing the Integrated Valuation of Ecosystem Services and Trade-offs (InVEST) model, we quantitatively assess the spatial and temporal patterns of water yields across four years: 1990, 2000, 2010, and 2020. Spatial heterogeneity in water yield across the lower reaches of the Malian River Basin was assessed using geographic detection techniques. Analysis revealed a fluctuating trend in total water yield from 1990 to 2020, characterized by an initial decrease, followed by an increase, and finally another decrease. Compared to 1990, total water yield in 2020 declined by 5.9×107 m3 (25.43% reduction). Furthermore, spatial analysis revealed a distinct pattern in water yield distribution across the basin. Higher water yield was observed in the southern and marginal areas, whereas lower yield characterized the northern and central regions. Land-use type significantly influenced water yield capacity. Ranked from highest to lowest, the order was as follows: construction land>bare land>agricultural land>low-coverage grassland>high-coverage grassland>shrub land>forest land>open water. Moreover, a significant positive correlation was identified between water yield and precipitation, suggesting that precipitation plays a key role in water production. Conversely, a negative correlation emerged between actual evapotranspiration and altitude. Our analysis identified precipitation and actual evapotranspiration as the primary drivers of spatial variations and temporal changes in water yield, with q values ranging from 0.616 to 0.735 and 0.517 to 0.653, respectively. These findings provide valuable scientific evidence to support the development, utilization, and management of soil and water resources in the loess plateau of eastern Gansu. Figures and Tables | References | Related Articles | Metrics

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Vegetation characteristics of herb communities on highway slopes of the Loess Plateau and their relationship with soil MAO Guangrui, ZHAO Jinmei, ZHU Gong, CUI Haiming, LIU Wanzhi 2024, 41 (5):  788-796.  doi: 10.13866/j.azr.2024.05.07 Abstract ( 121 )   HTML ( 11 )   PDF (3244KB) ( 82 )   This study examined the vegetation characteristics and species diversity of mixed herb communities in different years on the slope of expressway in the Loess Plateau, and explored the relationship between herb community characteristics, species diversity, and soil physical and chemical properties. The characteristics of herb communities, α species diversity, and their correlation with soil physical and chemical properties were studied using the Mantel test after 15 a, 12 a, 8 a, 4 a, and 2 a of restoration of herb communities on the highway slope of the Loess Plateau by space instead of time. In total, 13 species of 13 genera in 8 families were investigated in 15 a of slope restoration, 10 species of 10 genera in 7 families were investigated in 12 a of restoration, 5 species of 5 genera in 3 families were investigated in 8 years of restoration, 5 species of 5 genera in 3 families were investigated in 4 a of restoration, and 6 species of 6 genera in 4 families were investigated in 2 a of restoration. Patric species richness recovered in the order 15 a>12 a>8 a>2 a>4 a, the Shannon-Wiener and Simpson indices recovered in the order 15 a>12 a>2 a>8 a>4 a, and the Pielou evenness index recovered in the order 15 a>2 a>8 a>12 a>4 a. Patric species richness was significantly positively correlated with total porosity and capillary porosity, organic matter, total nitrogen, and total phosphorus (P<0.05), and the Shannon-Wiener index was significantly positively correlated with organic matter and total phosphorus (P<0.05). After spraying mixed grass species in different years on the slope, the herb communities mostly contained perennials, but there were differences in species composition and quantity of the community. The species richness, Shannon-Wiener index, and Simpson index of patric species showed an upward trend as the number of restoration years increased. Soil total porosity, capillary porosity, organic matter, total nitrogen, and total phosphorus were the key environmental factors affecting patric species richness and the Shannon-Wiener index. Figures and Tables | References | Related Articles | Metrics

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The physicochemical and strength characteristics of root-soil composite system in the Xiazangtan super large scale landslide area of the upper Yellow River FAN Qiuxuan, YANG Fucheng, FU Jiangtao, LIU Changyi, HU Xiasong, XING Guangyan, ZHAO Jimei, ZHANG Peihao 2024, 41 (5):  797-811.  doi: 10.13866/j.azr.2024.05.08 Abstract ( 106 )   HTML ( 2 )   PDF (14980KB) ( 40 )   For this study of the physical and chemical properties and mechanical characteristics of soil in the distribution area of Xiazangtan super large scale landslide of the upper Yellow River, plants and soil samples at different positions of the landslide were collected, and the plant growth index, soil density, water content, root content, shear strength index, and nutrient element content were measured. Spearman’s correlation analysis was used to explore the vegetation types, physical and chemical properties of soil, and the shear strength characteristics of the root-soil composite system in different positions of the landslide. The number of plant species tended to increase as the altitude decreased, and the dominant herbaceous herbs were Stipa aliena, Oxytropis ochrocephala, and Artemisia desertorum. The pH of the soil in the distribution area of the landslide was neutral to alkaline. The contents of organic matter, total nitrogen, and total phosphorus change greatly at the trailing edge of the landslide, whereas the contents of total potassium, alkali-hydrolyzed nitrogen, and four other nutrients change greatly but do not show obvious variation. The water content of soil first increases and then decreases with the decrease in altitude, while the density of soil increases as the altitude decreases, increasing by 7.05% and 5.88%, respectively. The cohesion c value and root content of the root-soil composite system first increased and then decreased as the altitude decreased. In addition, Spearman correlation analysis showed that the cohesion c value of the root-soil composite system was negatively correlated with altitude, but positively correlated with root content, organic matter, and water content. The results of this study have practical significance for guiding the prevention and control of geological disasters such as soil erosion, and shallow landslide in the upper reaches of the Yellow River, from Longyang Gorge to Jishi Gorge. Figures and Tables | References | Related Articles | Metrics

Plant Ecology

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Characterization of soil multifunctionality and its determining factors under moss crust cover in the arid regions of Northwest China LEI Feiya, LI Xiaoshuang, TAO Ye, YIN Benfeng, RONG Xiaoying, ZHANG Jing, LU Yongxing, GUO Xing, ZHOU Xiaobing, ZHANG Yuanming 2024, 41 (5):  812-820.  doi: 10.13866/j.azr.2024.05.09 Abstract ( 128 )   HTML ( 11 )   PDF (6881KB) ( 59 )   Biological soil crusts (BSCs) are the main active groundcover community in arid regions. BSCs can significantly affect the material cycle and energy exchange, improve the physical, chemical, and biological properties of surface soil, and influence the soil multifunctionality (SMF). Moss crust is an important type of BSCs. This study investigates the SMF variability of moss crust-covered and bare sand in the deserts of northwestern arid regions, and explored the main drivers of the variability. We analyzed eight crucial ecosystem function indicators. SMF was calculated by applying the mean method and factor analysis approach. We used the ordinary least square and structural equation modeling to explore the drivers of SMF changes. The results show that: (1) soil monofunctionality and SMF under moss crust cover were higher than those in bare sand (P<0.05). (2) The drivers of the SMF change in bare sand and under moss crust cover were very different. The main drivers of SMF in bare sand were aridity and soil water content, whereas the driver of SMF under moss crust cover was soil sand content (Sand). (3) The mean annual temperature had the largest indirect effect on changes in SMF for both soil in bare sand and under moss crust cover. Therefore, the development of moss crust significantly increased SMF and, in addition, modulated the relevant drivers of SMF. Our results are important for a deep understanding of the differences and drivers of SMF in desert soil with bare sand and under moss crust cover. Figures and Tables | References | Related Articles | Metrics

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Effects of different habitats and substrates on seed germination and seedling growth of Malus sieversii after passing through digestive tract of cattle BAI Shilin, LYU Yaya, SHI Xiaojun 2024, 41 (5):  821-829.  doi: 10.13866/j.azr.2024.05.10 Abstract ( 120 )   HTML ( 5 )   PDF (6691KB) ( 69 )   This study aimed to reveal the effects of different habitats and substrates on seed germination and seedling growth of Malus sieversii after passing through digestive tract of cattle. A controlled experiment was set up in field based on the different habitats and substrates in which seeds were deposited after passing through the digestive tract of cattle. The three habitats were as follows: forest edges, gaps, and understory. The four treatments were as follows: W (seeds through digestive tract+intact feces), P (seeds through digestive tract+broken feces), T (seeds through digestive tract+soil), and control C (seeds not through digestive tract+soil). The results showed that: The seed germination rates, seedling survival rate, and seedling biomass of M. sieversii were significantly different (P<0.05) in different habitats and treatments. In the forest edge habitat, seeds germinated rate was higher in soil substrate compared to fecal substrate, while the gaps and understory habitats showed the opposite trend. Seedling survival rate was significantly higher in the forest edge and gaps habitats compared to the understory habitat. Under the same treatment, seedling biomass was higher in the forest edge compared to the gaps, and higher in the gaps compared to the understory. Within the same habitat, seedling biomass from fecal substrate in forest edge and gap habitats surpassed that of soil substrate. The study revealed that the heterogeneity of habitat and substrate is the main reason that affects the seed germination and seedling establishment of M. sieversii after passing through digestive tract of cattle. Figures and Tables | References | Related Articles | Metrics

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Seed germination and seedling growth of typical sand-fixing plants in response to soil moisture YANG Zhuqing, WANG Lei, ZHANG Xue, SHEN Jianxiang, ZHANG Yijing, LI Xinyu, ZHANG Bo, NIU Jinshuai 2024, 41 (5):  830-842.  doi: 10.13866/j.azr.2024.05.11 Abstract ( 124 )   HTML ( 6 )   PDF (5987KB) ( 81 )   Seed germination and the seedling growth of sand-fixing plants are decisive aspects of land desertification management, and soil moisture is the main limiting factor affecting these aspects. In this study, we compared and analyzed the seed germination of three sand-fixing plants under different moisture gradients (4%, 6%, 8%, 10%, 15%, 20%, and 25%) in an indoor potting experiment using Hedysarum scoparium, Caragana korshinskii, and Artemisia desertorum to investigate the response of seed germination and seedling growth of sand-fixing plants to changes soil in moisture. The results showed that: (1) significant differences (P<0.05) were observed in the seed germination characteristics of the three sand-fixing plants as the soil moisture increased. The germination rates tended to increase and then decrease as the soil moisture increased. C. scoparium had the highest germination rate at 15% and 20% soil moisture (83.00% in both); C. korshinskii had the highest germination rate at 10% soil moisture (73.00%); and the seed germination rate of A. desertorum reached the maximum value of 77.50% at 15% soil moisture, and then slowly decreased, although the change was not significant. (2) The leaf area and root length of the three plants showed tended to first increase and then decrease as the soil moisture increased, and the specific leaf area and root:crown ratio tended to decrease and then increase. (3) The highest biomass of C. scoparium, C. korshinski, and A. desertorum seedlings was 0.0733 g, 0.1142 g, and 0.0363 g at 10%, 8%, and 20% soil moisture, respectively, and the aboveground biomass was significantly higher than the belowground biomass (P<0.05), although the allocation of belowground biomass by C. korshinski seedlings was higher than that of C. scoparium and A. desertorum. (4) The SOD activity, POD activity, CAT activity, Pro content, SS content, and Chl content of the three sand-fixing plants tended to increase and then decrease as the soil moisture increased, whereas the MDA content, membrane permeability, and relative water content tended to decrease and then increase. Based on the above results, it was concluded that the three sand-fixing plants of C. scoparium, C. korshinski, and A. desertorum had the best seedling growth at 15%, 8% and 8% soil moisture, respectively, through the analysis of the affiliation function method. Therefore, when these three sand-fixing plants are used for vegetation restoration, the changes in soil moisture caused by rainfall conditions should be fully considered in addition to the seeds’ own traits to improve the seedling emergence rate and the success of seedling growth. Figures and Tables | References | Related Articles | Metrics

Ecology and Environment

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Changes of farmland use intensity in the YLN region from 2000 to 2020 SANG Yiming, XIN Liangjie 2024, 41 (5):  843-855.  doi: 10.13866/j.azr.2024.05.12 Abstract ( 99 )   HTML ( 5 )   PDF (9258KB) ( 37 )   Farmland use intensity is an important factor to improve food production, alleviate the conflict between humans and land, and achieve sustainable agricultural development. Based on the farmland data obtained from high spatial resolution remote sensing images, this paper explores the farmland use intensity and its driving mechanism in the Yarlung Zangbo-Lhasa-Nyangqu River (YLN) region in 2000 and 2020 through a comprehensive evaluation index model. The results show that: (1) the degree of farmland use intensity in the YLN region has increased in the past 20 years, but the overall level is low. The farmland use intensity in 2020 was 38.2% higher than in 2000, which is mainly attributable to the increase in agricultural input, technological input, and the exploitation and utilization level. (2) There is a large difference in the change in farmland use intensity among different districts and counties; the high intensity areas migrated from east to west and increased in scope. The difference in farmland use intensity between east and west regions narrowed, and the number of low intensity districts and counties decreased. (3) The irrigation index, proportion of farmland area, and farmland quality have the most significant independent effects on the degree of farmland use intensity in the YLN, whereas socioeconomic factors, agricultural science and technology factors, and policy and environment factors interact with farmland resource endowment to increase the degree of impact on the farmland use intensity. Based on the above results, the following policy recommendations are proposed: the continuous promotion of agricultural science and technology innovation in the YLN region with a focus on regional differences, to realize sustainable development in high intensity areas and total factor inputs in low intensity areas, and facilitate the synergistic effects of agricultural policy and economy to coordinate and promote enhanced farmland use intensity in the YLN region. Figures and Tables | References | Related Articles | Metrics

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Construction and optimization of ecological network of Lanzhou-Xining urban agglomeration based on adaptive cycle XU Jing, WANG Deren 2024, 41 (5):  856-864.  doi: 10.13866/j.azr.2024.05.13 Abstract ( 92 )   HTML ( 1 )   PDF (5107KB) ( 34 )   The construction and optimization of an ecological network is an effective way to prevent landscape fragmentation and ensure regional ecological security. In this study, the Lanzhou-Xining urban agglomeration was selected as the research area. Using the adaptive cycle as the theoretical basis, coupled with the granularity inverse method and morphological spatial pattern analysis, the ecological sources were identified, and the comprehensive “potential-connectivity-resilience” ecological resistance surface was established. The circuit theory was applied to determine the vital ecological nodes and corridors. On this basis, an ecological network was constructed and optimization strategies were proposed. The results showed that the spatial distribution of ecological sources was uneven and fragmented, covering a total area of 4147.84 km2. As a whole, the resistance of the study area was characterized by a “high in the west and low in the east” trend, decreasing from the main city to surrounding areas. In total, 40 ecological corridors with a total length of 2278.59 km were extracted and distributed in the central part of the study area. Similarly, 24 ecological pinch points were extracted, primarily distributed in major river corridors and ecological sources; 25 ecological barrier points were identified, mostly located in ecological corridors. The structural indices of the ecological network α, β, and γ were 0.60, 2.00, and 0.74, respectively. By adding 12 stepping-stone patches, these indices increased by 18.33%, 14.00%, and 9.46%, respectively. These results can provide a references point for land-space development and ecological security maintenance in the Lanzhou-Xining urban agglomeration. Figures and Tables | References | Related Articles | Metrics

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Mechanism of climate influence on carbon storage in the Tarim River Basin and attribution under topographic differentiation CHENG Xiaoyu, LYU Jiehua 2024, 41 (5):  865-875.  doi: 10.13866/j.azr.2024.05.14 Abstract ( 119 )   HTML ( 7 )   PDF (10278KB) ( 61 )   Using the InVEST model, the carbon storage in the Tarim River Basin was estimated over a long period, and the spatial--temporal variation characteristic were described using trend analysis, correlation coefficients, and band set statistics to explore the overall spatial-temporal correlation between climate change and carbon storage in the study area; in addition, quantitative analysis of was performed the attribution of carbon storage in different topographic locations with the help of partial least square method. The results showed that: (1) From 2002 to 2020, the overall carbon storage level in the Tarim River Basin was low, following a horseshoe-shaped distribution characteristic (“low in the middle and high in the periphery”), and overall followed an increasing trend. (2) Carbon storage and average annual temperature, potential evapotranspiration, and average annual precipitation in the study area had the characteristics of opposite spatial distribution rather than the same spatial distribution, and the spatial differentiation was obvious. (3) The overall influence of climate factors on carbon storage followed the order: potential evapotranspiration>average annual temperature>average annual precipitation. (4) The potential evapotranspiration is the most significant variable for the levels I, III, and IV topography in the Tarim River Basin, whereas the average temperature and average precipitation are the most significant variables for the levels II and V topography in the Tarim River Basin. Figures and Tables | References | Related Articles | Metrics

Agricultural Ecology

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Effects of the regulation of water-salt-nitrogen on water-salt nutrient transport and yield in drip-irrigated cotton fields ZHANG Ziqi, YANG Lili, HE Xinlin, LI Xiaolong 2024, 41 (5):  876-893.  doi: 10.13866/j.azr.2024.05.15 Abstract ( 129 )   HTML ( 3 )   PDF (29899KB) ( 64 )   The effects of water, salt, and nitrogen (N) regulation on changes in the soil water, transport of salt nutrients, and growth indices and yield of cotton (Gossypium hirsutum) were analyzed under drip irrigation covered by film. A two-year three-factor full-combination field experiment was conducted to study the effects of three levels of irrigation (W1: 2700 m3·hm-2, W2: 3600 m3·hm-2, and W3: 4500 m3·hm-2), salinity (S1: 3 dS·m-1, S2: 6 dS·m-1, and S3: 9 dS·m-1), and N (F1: 105 kg·hm-2, F2: 210 kg·hm-2, and F3: 315 kg·hm-2). The effects of different combinations of water-salt-nitrogen on soil moisture, salinity, N distribution, plant growth, and yield were investigated. The results showed the following: the soil moisture was mainly located in the 30-40 cm soil layer, and the water content of different soil depths essentially first increased and then decreased. The average water content of the 0-40 cm soil layer in the bud and boll stages of S3F3W1 and S2F3W1 increased by 1.3%-21.8% compared with that of S1F3W1, and the average water content of the combination of S1F3 increased by 1.39%-13.83% compared with those of S1F2 and S1F1 under the same amount of irrigation. The soil salinity tended to decrease and then increase during the fertile period. The S1 treatment increased and then decreased the soil salinity as N application increased, and the soil salinity in S2 and S3 decreased as the N application increased. The N content was significantly higher with the F3 treatment than F1 or F2. In the W2 and W3 treatments, N slowly accumulated in the 40-60 cm soil layer, and the N content was significantly higher with the S1 treatment than S2 or S3. The soil moisture, salinity, and N content interacted; under appropriate soil moisture and N conditions, lower soil salinity enabled the plants to utilize nutrients more efficiently, which facilitated their growth, and thus enhanced yield. To obtain high economic benefit, the recommended rate of irrigation for low and medium saline soils is 3600 m3·hm-2 and the rate of N is 210 kg·hm-2. For highly saline soils, the recommended rate of irrigation is 4500 m3·hm-2 and the rate of N is 315 kg·hm-2. This study provides a theoretical basis to explore the mechanism of water and salt nutrient transport and the efficient use of water and fertilizer in cotton farmland ecosystems under multiyear drip irrigation under a membrane in arid areas. Figures and Tables | References | Related Articles | Metrics

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Monitoring soil salinization of cotton fields in the Aral Reclamation Area using multispectral imaging HONG Guojun, XIE Junbo, ZHANG Ling, FAN Zhenqi, YU Caili, FU Xianbing, LI Xu 2024, 41 (5):  894-904.  doi: 10.13866/j.azr.2024.05.16 Abstract ( 119 )   HTML ( 7 )   PDF (15070KB) ( 47 )   Given the difficulties in the field measurement of soil salinization in Xinjiang and the difficulty in quickly and broadly evaluating the potential hazards of soil salinization, this study considers cotton fields in the Aral Reclamation Area of Xinjiang as the research object, and uses multispectral remote sensing image data from Sentinel-2 SR and Landsat-9 OLI to construct a high-dimensional data set by comprehensively integrating 20 spectral indices and combining spectral indices. The optimal feature subset is screened using the method of exhaustive feature combination and cross-validation, and the inversion accuracy of soil salinization is compared for four machine learning algorithms (i.e., XGBoost, random forest, deep neural network, and K-nearest neighbor) under different feature combinations. Simultaneously, the difference in accuracy between Sentinel-2 SR and Landsat-9 OLI remote sensing images in soil salinization inversion is analyzed. The results show that: (1) The model constructed based on XGBoost algorithm can achieve high-precision prediction of cotton field salinization, with R2 higher than 0.74, MSE lower than 0.04, and MAPE lower than 0.13. (2) Under the condition of feature combination 1, Sentinel-2 SR (S3+GBNDVI) and Landsat-9 OLI (SI+NDVI) remote sensing images achieved the highest prediction accuracy using XGBoost algorithm. (3) Sentinel-2 SR image data in cotton field salinization prediction (R2=0.73-0.88) is better than that of Landsat-9 OLI image data. This study realizes the precise monitoring of soil salinization in cotton fields in the Aral Reclamation Area of Xinjiang, which should provide an effective and timely technical reference for soil salinization control and prevention in cotton fields in reclamation areas. Figures and Tables | References | Related Articles | Metrics