Table of Content

15 October 2023, Volume 40 Issue 10 Previous Issue    Next Issue

Weather and Climate

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Spatial-temporal evolution and impact factors during the climatic growing season in the Yellow River Basin from 1960 to 2020 ZHANG Zhigao, SUN Zixin, ZHANG Xiuli, GUO Kexin, LI Zhuoya, HAO Haijiao, CAI Maotang 2023, 40 (10):  1537-1546.  doi: 10.13866/j.azr.2023.10.01 Abstract ( 251 )   HTML ( 52 )   PDF (7583KB) ( 216 )   Data from 89 meteorological stations in the Yellow River Basin from 1960 to 2020 was used in this investigation. The Mann-Kendall mutation test as well as Morlet wavelet and correlation analyses were conducted to assess the spatial and temporal change characteristics and influencing factors at the beginning of the growing season (GSS), the end of the growing season (GSE), and the length of the growing season (GSL), as well as days with an active accumulated temperature of ≥10 ℃ (AT10) and active accumulated temperature of ≥10 ℃ (DT10) during the growing season. From 1960 to 2020 the GSS significantly advanced at a rate of -2.04 d·(10a)-1, while the GSE showed a delayed trend with a change rate of 0.85 d·(10a)-1, and the GSL was significantly prolonged at a rate of 2.88 d·(10a)-1; there were also significant regional differences. The GSS in the lower reaches of the Yellow River Basin was the earliest (February 23), while that in the upper reaches was the latest (March 30). Furthermore, the GSE in the upper reaches ended early (October 24), while that in the lower reaches was the latest (November 30), and the GSL in lower reaches was the longest (334.03 d), while that in the upper reaches was the shortest (297.33 d). The significant extension of GSL was mainly due to the significant advance of GSS. Over the past 61 years, the growth season indices were found to have a main period of approximately 28 a in the Yellow River Basin. GSS, AT10, and DT10 mutated in 1998, and GSL mutated in 2002. The changing trends for the growth season indices in the upper, middle, and lower reaches of the Yellow River Basin were consistent, with the largest change occurring in the lower reaches, followed by the upper and middle reaches, respectively. Correlation analyses showed that GSS advances in the Yellow River Basin were mainly related to spring warming over the past 61 years, and the delay of GSE was mainly due to autumn warming, the extension of GSL in the upstream and downstream areas was mainly due to spring warming, and the extension of GSL into the middle reaches was mainly related to autumn warming. Figures and Tables | References | Related Articles | Metrics

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Future climate change trends in the Shiyang River Basin based on the CMIP6 multi-model estimation data DAI Jun, HU Haizhu, MAO Xiaomin, ZHANG Ji 2023, 40 (10):  1547-1562.  doi: 10.13866/j.azr.2023.10.02 Abstract ( 218 )   HTML ( 12 )   PDF (20912KB) ( 125 )   Due in large part to global climate change, drought, flood, and high temperature events have increased significantly around the world in recent years. The Shiyang River Basin is in Northwest China and fringes onto a monsoon region, and is consequently, highly sensitive to climate change. The rapid development of oasis agriculture has led to high levels of development and the utilization of water resources in fragile ecological environments. Future climate change will aggravate the uncertainty of water resources in the basin, posing a threat to food security and economic development. Coupled General Circulation Models (GCMs) play an important role in the prediction of future climate change and formulation strategies to help devise adjustments accordingly. Based on the observed data in the historical period (1985-2014), the simulation capabilities of 11 climate models from the 6th international Coupled Model Intercomparison Program (CMIP6) in the Shiyang River Basin were evaluated. The equidistant cumulative distribution function method was applied to downscale climate data to obtain the future climate change trend for the basin as presented in this paper. The results show that the CMIP6 multi-model ensemble has good applicability in the Shiyang River Basin, as it accurately depicts the annual and seasonal distribution characteristics of climate factors, including precipitation, temperature, and potential evapotranspiration. The model performs well when simulating temperatures, in comparison to precipitation. While multimodel ensemble mean data perform better when simulating precipitation and temperature in the Shiyang River Basin, in comparison with other models. Under different future scenarios (2023-2100), precipitation, temperature, and potential evapotranspiration in the basin show a significant upward trend and increase with the radiative forcing increase. The late 21 century shows a greater increase in climate factors than the early and middle periods. Compared to the historical period, precipitation in the future could increase by 45.02% in the winter and 0.38% in the summer, and the greatest temperature increases can occur in spring and autumn. In the future, the aridity index of the Shiyang River Basin will decrease overall. The climate of the basin will tend to warm and humidify, with the summer season becoming drier while the other seasons become wetter than those in the historical period. The Minqin Basin located in the lower reaches of the basin is the area most sensitive to climate change. The research results have important reference value as they will help to address future climate change and ensure sustainable economic and agricultural development in the Shiyang River Basin. Figures and Tables | References | Related Articles | Metrics

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Variations in the NDVI characteristics during the summer and the climatic factor responses in the Qinling-Daba Mountains FU Shasha, PENG Wei, SHAO Aimei, CAI Dihua, LUO Miaoxin, LIU Zhaojing 2023, 40 (10):  1563-1574.  doi: 10.13866/j.azr.2023.10.03 Abstract ( 209 )   HTML ( 19 )   PDF (23279KB) ( 138 )   Monthly summer NDVI and meteorological data from February to August, 2001-2019, were used to analyze the changes in NDVI and the time lag effects of NDVI on climate factors in the Qinling-Daba Mountains. The results showed that NDVI presented an overall increasing trend in the Qinling-Daba Mountains, and the area with a highly significant increase in NDVI accounted for the largest proportion, with a value of 77.1%. There were positive correlations between NDVI and the temperature and precipitation, in which the correlations between NDVI and temperature were higher than those with precipitation. The response of the NDVI to climate factor changes showed significant time lag effects, and the spatial distributions of the lag time had regional differences. In the western regions of the Qinling-Daba Mountains, NDVI had a timely response to temperature changes and a 2-month lag response to precipitation changes. In the central regions, the lag time of the NDVI responses to temperature and precipitation changes varied with latitude. There were generally 1-and 0-month lag responses for temperature changes and 0-and 3-month lag responses for precipitation changes from north to south, respectively. In the northeastern regions there was a 3-month temporal lag in NDVI to the changes in temperature and precipitation. In the southeastern regions, NDVI had a timely response to temperature change and a 3-month lag response to precipitation change. This study provides scientific basis for summer storm and geological disaster warnings in the Qinling-Daba Mountains. Figures and Tables | References | Related Articles | Metrics

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Comparative analysis of the temperatures and rainfall in loess hilly regions using the ANUSPLIN model XIAO Xu, ZHENG Cheng, DING Chengqin, FAN Chenzhe, BAI Yuejiang, LIN Longchao, YAN Ting, GAO Yu, SHI Haijing 2023, 40 (10):  1575-1582.  doi: 10.13866/j.azr.2023.10.04 Abstract ( 172 )   HTML ( 15 )   PDF (6018KB) ( 184 )   Meteorological elements are the key factors used to assess the earth’s hydrothermal processes. Accurate acquisition of meteorological data is thus of great significance to the development of ecological protection systems and agricultural research. Loess hilly areas typically have hills and gullies, and consequently, the terrain seriously affects the interpolation of meteorological data and its accuracy. Based on the professional meteorological interpolation software ANUSPLIN, this study has used the daily temperature and rainfall data from 105 meteorological stations in and around the Yanhe River Basin from 2010 to 2021 as the basis, and three digital elevation models (DEM) with resolutions of 25 m, 90 m, and 1 km as covariables to interpolate the grid of temperature and precipitation in the loess hilly region. The spatiotemporal variation of precipitation was analyzed, and the applicability of the ANUSPLIN interpolation method in the loess hilly region evaluated. The results show that temperatures in the eastern extension area of the Yanhe River Basin were higher, when compared with those in the western area. The rainfall was lower in the central and northwestern regions when compared with the eastern regions. The distributions of temperature and rainfall were consistent with the laws of the previous meteorological station data. The ANUSPLIN model had a good adaptability to the spatial interpolation of temperature and rainfall in the loess hilly-gully region. In three different DEM resolution simulation scenarios, the accuracy of temperature interpolation was ranked as 25 m > 90 m > 1 km, and the rainfall interpolation accuracy was ranked as 90 m > 25 m > 1 km. Figures and Tables | References | Related Articles | Metrics

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Characteristics of precipitation changes in the Shule River Basin JI Zonghu, SUN Dongyuan, NIU Zuirong, WANG Xingfan, WU Lanzhen, MA Yali, CHEN Caiping, CUI Yanqiang 2023, 40 (10):  1583-1594.  doi: 10.13866/j.azr.2023.10.05 Abstract ( 195 )   HTML ( 17 )   PDF (15568KB) ( 313 )   The annual and monthly precipitation data from five hydrological stations in the Shule River Basin from 1956 to 2020, were analyzed using linear tendency, sliding average, cumulative anomaly, Mann-Kendall mutation test, wavelet analysis, and other methods. The interannual variation process for precipitation in the Shule River Basin and its variation characteristics, such as mutability, trend, periodicity, persistence, heterogeneity, and concentration, were evaluated. The results show that the annual precipitation at each station in the Shule River Basin showed different increasing trends, and the precipitation at each station showed different mutation characteristics. Over the previous 60 years, precipitation in the entire basin presents a relatively uneven distribution on the time scale, and the precipitation in the upstream area is more than that in the downstream. Specifically, the annual precipitation at Changmabao and Dangchengwan stations showed obvious increasing trends, while the increasing trend at Panjiazhuang station and Shuangtabao and Danghe reservoir stations was not obvious. The analysis indicates that precipitation in the basin will continue to show an increasing trend in the coming period. Figures and Tables | References | Related Articles | Metrics

Land and Water Resources

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Simulation study of summer ablation in the debris area of Qingbingtan Glacier No. 72 in Mt. Tomor HE Jie, WANG Puyu, LI Hongliang, LI Zhongqin, ZHOU Ping, MU Jianxin, YU Fengchen, DAI Yuping 2023, 40 (10):  1595-1607.  doi: 10.13866/j.azr.2023.10.06 Abstract ( 160 )   HTML ( 4 )   PDF (6654KB) ( 144 )   Debris-covered glaciers are widely distributed in Western China. Their ablation areas are covered by varying degrees of rock debris, and consequently, their melting statuses differ greatly when compared to debris-free glaciers. There is currently a need for melting simulations to better understand debris-covered glaciers. In this paper, driven by field meteorological data, an energy balance model for debris-covered glaciers has been used to simulate the energy and ablation in debris-covered areas of Qingbingtan Glacier No. 72 in Mt. Tomor, Tianshan. Based on the heat conduction process and the energy balance equation, the model calculates the debris surface temperature and the internal temperature of the debris, then estimates the subdebris melt using the internal debris temperature. The results showed that the modeled ablation was 0.39 m w.e. in the summer of 2008, and the simulation accuracy (R2 = 0.92, RMSE = ±0.03 m w.e.) was higher when compared with the field data. The simulated debris temperatures at the surface and a depth of 10 cm inside the debris were also found to fit well with the measured data (R2 = 0.91 and 0.60, respectively). During energy exchange in the debris area, net shortwave radiation was the only energy income item, and sensible heat flux was the largest energy expenditure item (49.7%), followed by the heat conduction flux (ablation heat consumption) (25.8%), net longwave radiation (19.8%), and latent heat flux (4.6%), while precipitation heat was <1%. Cloud cover had a significant impact on the meteorological and energy characteristics of the debris area. Under overcast conditions, the incoming shortwave radiation in the debris area decreased from 854 W·m-2 on sunny days to 587 W·m-2, while the downward longwave radiation and relative humidity increased, and the average ablation decreased by 12%, when compared with sunny days. In addition, the sensitivity analysis of the key parameters for debris shows that the simulated ablation is most sensitive to the changes in thermal conductivity, and the changes in albedo and surface roughness cannot be ignored. Figures and Tables | References | Related Articles | Metrics

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Equivalent pore size characteristics in the soil physical crust LIU Guanheng, WU Guanyu, LI Jiande, WANG Jian, YANG Qinxia, XUE Dong 2023, 40 (10):  1608-1614.  doi: 10.13866/j.azr.2023.10.07 Abstract ( 135 )   HTML ( 3 )   PDF (2178KB) ( 62 )   Pore size in the soil physical crust directly affects soil water infiltration and gas exchange. However, few studies have investigated the changes in pore size within the soil physical crust during rainfall events. This study has utilized Lou soil as the research object and artificial rainfall simulations, with microdisk infiltration apparatus to study the infiltration of the soil physical crust under different rainfall intensities and the pore size changes. The results show that under the pressure head of -0.5 cm, the infiltration rate of the structural crust decreases with the rainfall duration and then increases after 20 min. As rainfall progresses, the proportion of large pores in the two types of crusts begins to decrease, and the proportion of medium pores increases. The proportion of small pores in the structural crust decreases at 20 min, and the proportion of medium pores in the sedimentary crust remains unchanged at 10 min. The average pore size for the two types of crusts was found to decrease with the extension of the rainfall duration. During the increase in the negative pressure head, the effective infiltration capacity of the soil crust decreased. When the soil crust developed completely, the infiltration rate tended to be stable. Figures and Tables | References | Related Articles | Metrics

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Spatial differentiation characteristics of soil salinity in Minqin Basin, downstream of Shiyang River, China LIU Xin, HAO Yuanyuan, HUA Limin 2023, 40 (10):  1615-1624.  doi: 10.13866/j.azr.2023.10.08 Abstract ( 199 )   HTML ( 12 )   PDF (5663KB) ( 209 )   Clarifying the spatial variability of soil salinity is the aim of soil salinization research and saline-alkali land improvements. In this study, the Minqin Basin in the lower reaches of the Shiyang River in the arid inland river basin was selected as the study area. By analyzing the statistical characteristics, spatial autocorrelation, variability, and distribution patterns of soil salinity in situ data of the 0-30 cm soil layer, the changes in the spatial heterogeneity of soil salinity could be explored to provide a theoretical basis for soil salinity in the study area. The measured soil salinity content and its variation range both decreased as the soil layer increased, and both were in a skewed normal distribution. Moran’s I index showed a “∽” type fluctuation trend, and the range of values increased with the soil layer, and the positive (negative) spatial autocorrelation decreased as the distance increased (negative spatial autocorrelation of 0-10 cm was opposite). The exponential model was the most suitable for use with the variogram. The R2 increased with soil depth (0.62→0.69→0.81), and the RSS was 0.0002. Variation rules of C0/(C0+C) and A0 were consistent, and the spatial heterogeneity ranged from weak to strong to moderate with soil depth. Accuracy of the interpolation was 10-20 cm > 20-30 cm > 0-10 cm. The soil salinity of the three layers had spatial differentiation characteristics, and the degree of salinization increased gradually from southwest to northeast in the horizontal direction (the same soil layer). In the vertical direction (different soil layers), the distribution patterns changed from simple to complex, and gradually tended to patches (10-20 cm) and spots (20-30 cm) from the aggregation state (0-10 cm). Nonsalinized soil (<1.50%) and four different levels of saline soil were distributed in the three soil layers, and the area of saline soil was moderate (>70.00%) > strength (approximately 20.00%) > mild (approximately 9.00%) > saline soil (<0.50 %). Figures and Tables | References | Related Articles | Metrics

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Spatiotemporal characteristics of sierozem and aeolian soil moisture levels in a desert steppe YANG Shuangqi, SONG Naiping, WANG Xing, CHEN Xiaoying, CHANG Daoqin 2023, 40 (10):  1625-1636.  doi: 10.13866/j.azr.2023.10.09 Abstract ( 188 )   HTML ( 9 )   PDF (6290KB) ( 111 )   Due to the interference from human activities and natural factors, the primary sierozem area in the Ningxia desert steppe has gradually shrunk due to long-term desertification and formed island patches within the surrounding aeolian soil. To reveal the spatiotemporal characteristics of soil moisture after sierozem desertification, a comparative study was carried out between the large (200-300 m2), medium (approximately 100 m2), and small (approximately 50 m2) sierozem patches and the surrounding aeolian soil in Wanjigou Village, Yanchi County, Ningxia, during the growing season (May to October from 2017 to 2019). The uniform rainfall pattern in 2017 led to the highest annual average soil moisture content. While the annual rainfall in 2018 was slightly higher than that in 2017, it was concentrated in the spring, and there were almost no rainfall events in the summer and autumn, resulting in a low soil moisture content throughout the year. The summer rainfall pattern in 2019 resulted in the highest average soil moisture content during the summer period. The soil moisture content of sierozem in the 0-100 cm soil layer first showed an increase and then a decrease with increases in soil depth and was greatest in the 10-40 cm soil layer. The soil moisture content of the aeolian soil increased with soil depth, and the soil moisture content of the 0-20 cm soil layer was much lower than that of the 20-100 cm layer. The moisture content of sierozem in the 0-20 cm soil layer was greater than that of the aeolian soil, while the moisture content of the sierozem in the 20-100 cm soil layer was significantly lower than that of the aeolian soil (except for small and medium-sized patches in 2018). There was no significant difference (P > 0.05) in the soil moisture content of the sierozem between the different patch sizes, except that the soil moisture content of the aeolian soil surrounding the large-sized patches was significantly greater than that of the small and medium-sized patches (P < 0.05). The water storage of sierozem in the 0-100 cm soil layer was generally lower than that of the aeolian soil, and the variation range was smaller than that of the aeolian soil during the same period. When the rainfall was <16 mm, the water in both soil types was in a consumption state. When the rainfall ranged from 16 to 25 mm, the water storage capacity of the sierozem was greater than that of the aeolian soil, but when the rainfall was >25 mm, the water storage capacity of the aeolian soil was greater than that of the sierozem. The soil moisture content in the desert steppe was dominated by the rainfall, its distribution pattern, and soil type. The moisture contents of the sierozem and aeolian soils differ in their profiles, as well as in response to rainfall. Figures and Tables | References | Related Articles | Metrics

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Influence of freezing and thawing on the shear resistance of meandering riverbank soil in the Yellow River source region LIU Guosong, ZHU Haili, ZHANG Yu, LIU Yabin, LI Guorong 2023, 40 (10):  1637-1643.  doi: 10.13866/j.azr.2023.10.10 Abstract ( 121 )   HTML ( 2 )   PDF (2196KB) ( 120 )   Soil shear resistance in the Riparian zone directly affects riverbank stability. Furthermore, the influence of freezing and thawing on the structure and mechanical properties of alpine meadow soils is directly related to the collapse frequency and lateral migration of the river bank in the source region of the Yellow River. To investigate the change rules and generation mechanisms of the root bearing soil mass, the shear strength index in the meandering Riparian zone of the source region of the Yellow River under the effects of freezing and thawing were assessed. The subsequent impacts of different root contents on the soil mass shear strength index were also determined using an indoor freeze-thaw direct shear test with remolded soil. The experimental results show that plant roots can significantly and increasingly enhance soil cohesion, which can range from 2.7% to 77.9%. Variations in the internal friction angle with root content were not significant. The freeze-thaw cycle weakens soil cohesion, especially in the early stages. The maximum decrease in cohesion of 19.0% occurred with three freeze-thaw cycles, after which the changes stabilized, while the internal friction angle showed a slight increasing trend. The effects of the freeze-thaw action on the shear strength index of the rooted soil is smaller than that of the plain soil. Under the same freeze-thaw frequency conditions, the decrease in cohesion of the rooted samples was found to be smaller than that of the plain soil samples. The root systems of meadow plants can block the changes in soil temperature, reduce the decrease in soil cohesion, and increase with the root content. When the root content reaches 11%, its weakening effect on soil cohesion is 4.2%-27.7% less than that of plain soil. The Riparian zone, as the source area of the Yellow River, should strengthen the protection of riverside meadow vegetation, maximize the role of the root system in enhancing Riparian stability, and protect river ecology. Figures and Tables | References | Related Articles | Metrics

Plant Ecology

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Time lag and cumulative effect of drought on gross primary productivity in the grasslands of northern China WU Rina, LIU Buyun, BAO Yuhai 2023, 40 (10):  1644-1660.  doi: 10.13866/j.azr.2023.10.11 Abstract ( 267 )   HTML ( 23 )   PDF (28866KB) ( 180 )   In recent years, with global warming, the increase of drought events has a more important impact on the photosynthesis of vegetation, and also seriously affects the balance of terrestrial ecosystems. Based on SPEI base v.2.7 and GOSIF GPP data set, this paper studies the cumulative and time-delay effects of drought on GPP in northern grassland. Sen’s slope test, MK trend test and Mann-Kendall mutation test were used to study the temporal and spatial changes of GPP and SPEI during the study period. Pearson correlation analysis method was used to explore the cumulative and time-delay effects of drought on GPP in the north grasslands. The results showed that: (1) From 2001 to 2020, the annual average GPP of the northern grasslands showed a spatial distribution pattern of high in the northeast and low in the southwest, and the annual average SPEI showed a spatial distribution pattern of low in the northeast and high in the southwest, and the annual average of SPEI and GPP showed an upward trend over time. (2) Drought has a cumulative effect on 84.99% of the northern grassland, and the longest cumulative time scale is mainly concentrated in 3-4 months, covering 39.82% of the northern grassland; Drought had a lagging effect on 63.11% of the northern grassland, and mainly occurred in 7 months, covering 19.73% of the northern grasslands. (3) By comparing the variation trends of drought and drought under different water conditions, we found that the cumulative effect of drought on grassland GPP was stronger than the time-lag effect. Figures and Tables | References | Related Articles | Metrics

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Factors affecting Picea schrenkiana regeneration on different slope directions WANG Guanzheng, CHANG Shunli, WANG Jianping, ZHANG Yutao, SUN Xuejiao, LI Xiang 2023, 40 (10):  1661-1669.  doi: 10.13866/j.azr.2023.10.12 Abstract ( 173 )   HTML ( 8 )   PDF (3797KB) ( 193 )   The influence of different slope-facing environmental factors on the natural regeneration of Picea schrenkiana in the middle section of the northern slope of Tianshan Mountains was investigated. A series of plots were established on shady, semishady, semisunny, and sunny slopes at the same altitude, in a Picea schrenkiana forest to develop the structure equation model for the regeneration index which uses different slope-facing environmental factors. According to the environmental characteristics of the different slope-facings, the relationship between the survival status of Picea schrenkiana seedlings and environmental factors was analyzed. The results showed that the semishady and semisunny slopes were more suitable for the survival and growth of seedlings, and the regeneration indexes of the two slopes (0.065 and 0.057) were significantly higher than those of the shady and sunny slopes. Litter was found to have a dual effect on the regeneration of Picea schrenkiana. The undecomposed litter layer was too thick to be beneficial to regeneration, while the rich organic matter could promote the formation of a high nitrogen environment in the soil, which was conducive to the regeneration of seedlings. The influence of different slope-facing environmental factors on the regeneration index was in the order of total nitrogen content (0.60) > adult tree density (0.46) > litter half-decomposed layer (0.37) > total potassium content (0.24) > organic matter content (0.23) > total phosphorus content (-0.16) > available phosphorus content (-0.32) > litter undecomposed layer thickness (-0.34). Overall, the regeneration of Picea schrenkiana seedlings in the region was best on the semishady and semisunny slopes with a closure degree of approximately 0.6 and litter thickness of approximately 2.5 cm, as well as high total nitrogen and total potassium contents in the soil. Figures and Tables | References | Related Articles | Metrics

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Calorific values of forest surface fuels in the eastern Tianshan Mountains of Xinjiang, China ZHOU Xiang, WANG Peng, Bumaliyamu MAIMAITI, WANG Qiuyan, YUE Jian 2023, 40 (10):  1670-1677.  doi: 10.13866/j.azr.2023.10.13 Abstract ( 132 )   HTML ( 3 )   PDF (2964KB) ( 105 )   Forest surface combustibles are one of the important factors in forest fire propagation, and their calorific values are an important index by which to assess combustibility. This study has aimed to assess the surface fuels available in four typical vegetation types in the eastern Tianshan Mountains of Xinjiang, China. The characteristics of the surface fuel calorific values and relationship with ignition point and absolute moisture content were analyzed. The results show that in coniferous and broad-leaved forests, there were significant differences between herb and litter components, while in shrub forest, there were significant differences between shrub and litter components. Within the same forest the calorific values were litter > herb > shrub > humus. The calorific values in the coniferous forests were the highest among the herbaceous fuel components (19.38 ± 0.08 kJ·g-1), while those in the coniferous forests were highest among the litter fuel components (19.55 ± 0.05 kJ·g-1). Differences were identified in the relationship between the calorific value and the ignition point of the surface combustibles for the different components. There was a significant correlation between the burning point of the shrub fuel components and the calorific value (R2 = 0.81, P < 0.01), and between the burning point of litter fuel components and the calorific value (R2 = 0.38, P < 0.05). However, there was no significant correlation between the burning point and calorific value of the herbs and humus (P > 0.05). In addition, there was no significant correlation between the calorific values of the surface fuel and the absolute moisture content of all forest types. Forest type, tree species, physical and chemical properties, and other conditions were thus found to have a comprehensive effect on the calorific values of the different fuels. The results of this study provide a theoretical basis for forest fire management in the eastern Tianshan Mountains as they will help to accurately predict the calorific energy and potential forest fire risks and provide data support for in-depth research on regional surface fuels. Figures and Tables | References | Related Articles | Metrics

Ecology and Environment

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Influences of railway viaducts on local wind power: A case study of the Shashangou Bridge used by the Dunge Railway XUE Chengjie, ZHANG Kecun, AN Zhishan, ZHANG Hongxue, PAN Jiapeng 2023, 40 (10):  1678-1686.  doi: 10.13866/j.azr.2023.10.14 Abstract ( 143 )   HTML ( 4 )   PDF (11303KB) ( 92 )   The dynamic wind environment characteristics on the east and west sides of the Shashangou Bridge used by the Dunge Railway were investigated using field observations, indoor analysis, and CFD numerical simulations. The results show that the sand-driving winds on the east and west sides of Shashangou Bridge were mainly NW and WNW winds in the spring and summer, and SE and S winds in the autumn and winter. The annual sand transport potential on the west side of Shashangou Bridge is 284.19 VU, which indicates a medium wind energy environment. The sand transport potential was determined to be 27.4 VU, and the sand transport with the wind direction was 124°. The directional variability index is 0.10, which indicates a small ratio and variable wind direction. The sediment transport potential on the east side of Shashangou Bridge is 31.24 VU, indicating a low wind energy environment. The results of the sediment transport potential were 8.97 VU, while the results of the sediment transport wind direction were 91°, and the directional variability index was 0.29, indicating a medium ratio. The average wind speed, frequency of sand-driving wind, sand transport potential, and resultant sand transport potential on the west side of Shashangou Bridge were larger, indicating that the monitoring and control of sand damage on the west side of the bridge should be improved. According to the characteristics of the wind dynamic environment on the west side of the bridge when combined with the flowing dune, the numerical simulation analysis results show that the wind speed in the overhead area and bridge deck is greater than the sand-driving wind speed, and the sand transport capacity was strong, indicating that sand accumulation does not readily occur. However, with the advance of sand dunes, the possibility of sand accumulation at the bottom of the bridge and wind sand on the rail increases. Figures and Tables | References | Related Articles | Metrics

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Study on main aeolian sand environment characteristics and formation mechanism in Wuzhumuqin Sandy Land ZHANG Hao, DANG Xiaohong, MENG Zhongju, GAO Yong, LIU Yang, QIN Qingchuan 2023, 40 (10):  1687-1697.  doi: 10.13866/j.azr.2023.10.15 Abstract ( 186 )   HTML ( 9 )   PDF (13995KB) ( 144 )   Mastering the regional wind sand movement environment and sediment particle size characteristics is the key to studying wind sand flow, and is of great significance for the prevention and recovery of regional wind sand disasters. Based on the wind regime data of Wuzhumuqin Sandy Land, this paper studies the variation characteristics of sand driving wind regime and sand transport potential, and reveals the spatial differences of sand environment in this area by combining with the sediment particle size data. The results show that:（1）The annual average frequency of sand blowing in the Wuzhumuqin sandy land is 33.8%, with an average wind speed of 3.34-5.40 m·s-1, and an average sand blowing wind speed of 6.46-8.49 m·s-1. The frequency and wind speed of sand blowing in the north of the sandy land are greater than those in the south, and those in the west are greater than those in the east. （2）The overall annual frequency and wind speed of sand storms are the highest in spring. The wind direction of sand storms is mainly in the southwest direction, and the frequency in the WSW direction is the highest.（3）The sand transport potential in the sandy land is 19.2-193.7 VU, which is generally a low wind energy environment. The wind conditions are mostly sharp bimodal wind conditions. The sand transport potential in the north of the sandy land is greater than that in the south, and that in the west is greater than that in the east. Throughout the year, sand material is transported to the east and northeast, and spring is the most important period of wind sand activity.（4）The sandy land is mainly composed of coarse and medium sand components, with soil particle sizes in the south and west being coarser and finer in the east. The sorting of sediment in the northern and eastern parts of the sandy land is poor, and the particle size components are greatly influenced by external factors. Overall, the sandstorm activity in the northern part of the sandy land is the strongest, making it suitable for artificial planting or laying sand barriers to fix sand. Protection forest is planted in the east of the sandy land to avoid the continuous eastward movement of sand. Figures and Tables | References | Related Articles | Metrics

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Spatiotemporal evolution characteristics and influencing factors of production-living-ecological spaces in the farming-pastoral ecotone: Taking Hohhot of Inner Mongolia as an example DANG Hui, RONG Lihua, LI Yitong, ZHAO Mingjun 2023, 40 (10):  1698-1706.  doi: 10.13866/j.azr.2023.10.16 Abstract ( 177 )   HTML ( 9 )   PDF (9018KB) ( 107 )   The agropastoral ecotone is an important ecological security barrier and grain producing area in northern China. Elucidating the spatial evolution law and influencing factors of production-living-ecology spaces in the ecologically fragile areas for land space optimization and sustainable development is extremely important. In this study, the methods of land use dynamic degree, land transfer matrix, and geographical detector were used to explore the spatial evolution characteristics and influencing factors of production-living-ecological spaces in Hohhot, a typical farming-pastoral ecotone in Inner Mongolia, from 2000 to 2020. The results show that during the study period, the overall dynamic changes in the production-living-ecological space of Hohhot were gentle (0.02%-0.04%). The spaces for ecology, agricultural production, and animal husbandry decreased, while the spaces for life and other production increased. From 2000 to 2020, the spatial patterns for production-living-ecological in Hohhot changed significantly, and this was mainly manifested in the occupation of agricultural and animal husbandry production spaces by the living space outside the urban area, and the mutual transformation of agricultural production, animal husbandry, and ecological spaces in the Tumochuan Plain and its northern and southeastern hilly areas. During the study period, the mutual transformation of ecological, agricultural, and livestock production spaces was intense, but this decreased after 2010. Living spaces and other production spaces were in a state of net inflow, especially in the latter decades. The average slope is the dominant factor affecting the spatial layout of agricultural and animal husbandry production (0.24-0.4). Industrial development, human activities and agricultural production scales have a greater impact on the local spatial patterns. Based on refined governance, the role of policy guidance is increasingly prominent. Figures and Tables | References | Related Articles | Metrics