Table of Content

    25 September 2023, Volume 78 Issue 9 Previous Issue   
    Land Use and Carbon Peak & Carbon Neutrality
    Dynamics and driving mechanisms of cultivated land at county level in China
    ZHANG Jie, LIU Yujie, ZHANG Ermei, CHEN Jie, TAN Qinghua
    2023, 78 (9):  2105-2127.  doi: 10.11821/dlxb202309001
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    The land conversion processes concerning non-agricultural and non-grain production areas have prominently decreased arable land availability, which substantially impacted grain production capacity and threatened national food security. Thus, it is critical to establish a novel scientific approach to identify spatio-temporal evolution patterns of land conversion and its influencing factors in different stages. This study evaluates the evolutionary characteristics of non-agricultural and non-grain fields by constructing a comprehensive index system that considers factors like cultivated land resources, social and economic conditions, and farmers' subjective perspectives, using a county as the basic research unit. For a comprehensive analysis, a geographical detector model was utilized to quantify driving factors in different stages. The results indicated spatial clustering effects for non-agricultural and non-grain fields throughout China, particularly in the eastern region beyond the "Hu Huanyong Line". Further analysis revealed a spatial pattern for non-grain conversion phenomenon was more intense in the southwestern than the northeastern fields. Over the past four decades, non-agricultural fields recorded an area expansion, but the year-wise area increase was gradually reduced, while non-grain areas exhibited a "growth-stable" change pattern. Although progress in non-grain was less in primary producing areas over the last 40 years, an increase of 1.49 times and 1.33 times was recorded from 2010 to 2020 in PSB (production and sales balance area) and Mrt (marketing) areas, respectively. Compared to the period 1980-2000, the rate of non-agricultural conversion in primary producing areas decreased by 77% during 2010-2020, while the rate of non-agricultural conversion increased by 1.63 and 4.65 times for PSB and Mrt regions, respectively. Based on these findings, this paper puts forward suggestions, such as setting control rules and subsidy mechanisms according to area classification, promoting control policies based on regional considerations, strengthening dynamic monitoring and risk warning, as well as enhancing supervision and assessment.

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    Evaluation of suitability, adaptability, and reserve potential of construction land on the Qinghai-Tibet Plateau
    YANG Hua, XU Yong, ZHOU Kan, WANG Lijia, XU Lin
    2023, 78 (9):  2128-2146.  doi: 10.11821/dlxb202309002
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    Construction land is the main carrier of human activities such as production and living. Conducting the suitability evaluation of construction land on the Qinghai-Tibet Plateau (QTP) holds the significant implications for harmonizing the relationship between ecological preservation and human activities, as well as promoting the optimization of population and industrial spatial layout. However, there are no relevant studies which provide a complete assessment of the construction land suitability (CLS) on the QTP. In this paper, we developed a model- based CLS assessment framework coupling of patterns and processes to calculate the CLS across the entire QTP based on the CLS evaluation model. Then, using the land-use data of 1990, 2000, 2010, and 2020, we examined the adaptability of existing construction land to the assessment result of CLS through the adaptability index and vertical gradient index, and further analyzed the internal limiting factors of maladaptive construction land. Finally, we calculated the potential of reserve suitable construction land. This article includes four conclusions: (1) The area of CLS classes, including highly suitable, suitable, moderately suitable, marginally suitable, and unsuitable, are 0.33×104 km2, 10.42 ×104 km2, 18.06×104 km2, 24.12×104 km2, and 205.29×104 km2, respectively, accounting for 0.13%, 4.04%, 7.00%, 9.34%, and 79.50% of the total land area, respectively, with the unsuitable class being predominant. The highly suitable, suitable, and moderately suitable classes are mainly distributed in regions such as the Qaidam Basin, Yellow River-Huangshui River Valley, Gonghe Basin, Songpan Plateau, Shigatse Valley, Lhasa-Shannan Valley, and Nyingchi Valley. (2) The construction land adaptability index are 85.16%, 85.93%, 85.18%, and 78.01% in 1990, 2000, 2010, and 2020, respectively, with an average adaptability index exceeding 80% on the QTP. The distribution of existing construction land generally conforms to the characteristics of construction land suitable space, but with a significant spatial difference. (3) From 1990 to 2020, the mal-adaptive and low-adaptive construction land on the QTP is mainly composed of rural residential land, transportation land, and special land, the proportions of urban construction land and other construction land are rapidly increasing. The vertical gradient of elevation and slope of construction land have gradually strengthened, and the spatial extent has expanded. Construction land in the southern Qinghai Plateau, western Sichuan alpine canyon region, and Qilian Mountains is subjected to constraints of both elevation and slope, while the main limiting factor in the northern Tibetan Plateau, Gangdise Mountains, and Himalayan Mountains is elevation. (4) The potential area of reserve suitable construction land on the QTP is 12.41×104 km2, constituting 4.81% of the total land area, with suitable and moderately suitable classes dominant. The per capita potential area of reserve suitable construction land is 9928 m2/person. The Qaidam Basin has the richest reserve of suitable construction land, while the Gonghe Basin and Lhasa-Shannan Valley can serve as preferred destinations for ecological migration. The research results can provide decision-making references for ecological migration and optimizing the spatial distribution of human activities on the QTP.

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    Regional regulation and interregional coordination of cultivated land protection in China from the perspective of "Greater Food" approach
    ZHU Xiaohua, ZHANG Yan, ZHU Yuanyuan
    2023, 78 (9):  2147-2162.  doi: 10.11821/dlxb202309003
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    The foundation of food production lies in cultivated land, and the protection of cultivated land is the cornerstone to ensure national food security. Based on the food consumption data of Chinese residents from 1987 to 2020, this study introduced the concept of virtual land and imported food data to estimate the cultivated land area required for food and virtual imported cultivated land, and analyzed the overall and zonal agricultural planting structure of China at this stage. On this basis, it constructed the zonal regulation and coordination mechanism of cultivated land protection in China in the context of "Greater Food" approach. The Chinese dietary structure presented the characteristics of increasing animal food consumption and gradually focusing on meat. Therefore, this study found the following conclusions on the regulation of cultivated land: (1) From 1987 to 2020, the cultivated land required by the Chinese dietary structure gradually approached the critical value. The virtual imported cultivated land increased by nearly 20 times, and the cultivated land demand was changing to the orientation of diversified planting demand. (2) The total agricultural planting structure in China has not yet met the dietary consumption demand of residents, and there are problems of structural imbalance, insufficient supply, and excess inventory. There are significant differences in the agricultural planting structure of the nine major agricultural areas of China. (3) The transformation of cultivated land protection should take the protection of existing cultivated land resources as the base, the transformation of planting structure, the regulation of agricultural production layout as the main force, the implementation of regional coordination and the guarantee of appropriate international imports as the assistance, and the transfer of pressure on cultivated land resources to the living community as the core from a systematic perspective, so as to build a multi-directional protection mechanism for China's cultivated land. This study can provide a scientific reference for the formulation of cultivated land protection strategy oriented by food balance demand and provide a theoretical menu for ensuring national food security and sustainable resource utilization in the new era.

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    Characteristic evolution and trend prediction of cultivated land landscape fragmentation in China from 1990 to 2020
    LIU Jing, JIN Xiaobin, XU Weiyi, WANG Shilei, ZHOU Yinkang
    2023, 78 (9):  2163-2185.  doi: 10.11821/dlxb202309004
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    It is of great significance to systematically reveal the multi-scale evolution patterns and future trends of cultivated land landscape fragmentation (CLLF) in China since 1990 for optimizing the utilization and management of cultivated land resources and promoting appropriate scale agricultural management. This paper first discusses the theoretical cognition of CLLF, then systematically analyzes the evolution of multi-scale characteristics and scale nesting effect of CLLF at agricultural, provincial, municipal and county scales in China from 1990 to 2020, and predicts CLLF long-term evolution trend based on the data of China's land use in the study period and the spatial analysis and mathematical statistics methods such as Theil Index, scale variance, and Markov chain. Results showed that: (1) The pattern characteristics of CLLF in China show obvious scale differences, manifested as a ladder pattern along the three steps of China's terrain at the county scale, a cluster pattern of dual core, ring core group and belt area relying on the "Hu Huanyong Line" at the municipal scale, and a gradually strengthened concentric circular layered structure from east to west and from northeast to southwest at the provincial scale. The average contribution of differences in county, municipal, provincial and agricultural scales to the overall difference of CLLF in China is 84.87%, 14.64%, 0.31% and 0.18%, respectively, indicating that the smaller the scale, the better it can reflect the spatial heterogeneity of CLLF. (2) CLLF showed a trend of enhancement on multiple scales during 1990-2020, but the growth rate slowed down over time. Among them, the development of CLLF was the most intense during 2000-2010. (3) CLLF in China during 1990-2020 generally increased in the east and decreased in the west, but there were great differences in spatio-temporal evolution of the trend, intensity and spatial range at different scales. Spatially, major grain-producing areas such as the Huang-Huai-Hai Plain, the central and eastern parts of middle-lower Yangtze Plain and the Sichuan Basin became high-value agglomeration areas with increased fragmentation. (4) The long-term CLLF in China will follow the development pattern of a gradual increase from low to high. The counties with low- or relative low level of fragmentation will decrease greatly, while the counties with higher- or high-level will increase significantly. Meanwhile, different neighborhoods will also lead to significant differences in the long-term evolution of CLLF.

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    Dynamic evolution and driving effects of carbon emissions from grain production in China
    ZHANG Qingqing, QU Yanbo, ZHAN Lingyun, SU Desheng, WEI Chuanchen
    2023, 78 (9):  2186-2208.  doi: 10.11821/dlxb202309005
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    Ensuring food security under the "double carbon" goal is an important issue for China to tackle climate change and build a community of human life. This paper employs the life cycle assessment method to gauge the grain production carbon emissions in China and its 31 provincial-level regions from 1997 to 2020, and uses the Dagum Gini coefficient, standard deviation ellipse and kernel density methods to explore the dynamic evolution characteristics. It further identifies the underlying factors of China's grain production carbon emissions, as well as their spatio-temporal impacts, under a comprehensive, period-based, and regional-level decomposition perspective. The results show that: (1) During the inspection period, China's total carbon emissions from grain production showed an upward trend, with an annual growth of 1.30%, yet since 2017 it has been in a continuous downward trajectory. Material inputs and straw burning account for the lion's share of emissions. The total carbon emissions in 2020 amounted to 494.78 million tons. (2) With regard to the three major grain production functional areas and six grain crop planting system areas, the carbon emissions of grain production in the main grain production areas, the middle and lower reaches of the Yangtze River and North China provinces have been in the forefront during the investigation period, while those in the main grain sales areas have displayed a diminishing trend. (3) The absolute difference of China's grain production carbon emissions enlarged manifesting as a tendency of high level convergence and widening of regional disparities. (4) China's grain production carbon emissions are jointly affected by economic, social, technological, demographic and natural factors. With gross agricultural output value and gross grain output serving as the key influential factors, they display negative spatial spillover effects; meanwhile, regional economic structure, labor saving technology, and agricultural production composition demonstrate diametrically opposite effects. The stage effect takes the 11th Five-Year Plan period (2006-2010) as the node, and the driving factors tend to be simplified. In the regional effect, the driving factors from the main sales area, the main production area to the balanced production and marketing area tend to be complex. This study provides a theoretical and methodological basis for promoting green grain production under the "dual carbon" strategy.

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    Estimation of soil carbon storage change from land use and management at a high spatial resolution in China during 2000-2020
    TONG Rongxin, LIANG Xun, GUAN Qingfeng, SONG Yu, CHEN Yuling, WANG Qinyi, ZHENG Lina, JIN Qun, YU Yanping, HE Jie, XIONG Xuehui, LIAO Weilin
    2023, 78 (9):  2209-2222.  doi: 10.11821/dlxb202309006
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    Soil organic carbon (SOC) storage and soil carbon sinks play a crucial role in the global carbon cycle of terrestrial ecosystem. However, many previous studies of soil carbon storage and sinks utilized low-resolution land use dataset, with limited focus on soil carbon sinks from farmland and grassland management. To address this issue, this study employed a series of accounting models to estimate the carbon sink from farmland and grassland management, the carbon sink from forest management, changes in soil carbon storage, changes in carbon storage due to land use conversion from 2000 to 2020, as well as the soil carbon storage in China in 2000 and 2020 using a 30 m-resolution land use dataset. The results showed that the national carbon sink from farmland management in China was approximately 17.918 Tg C a-1 and the carbon sink from grassland management was approximately 20.171 Tg C a-1 during 2000-2020. The carbon sink from forest management in China was approximately 81.622 Tg C a-1 during 2000-2020. The soil carbon storage (0-100 cm) in China increased from 86.074 Pg C in 2000 to 86.771 Pg C in 2020. The soil carbon storage increased by approximately 34.850 Tg C a-1 from 2000 to 2020. The land use transformation during the study period resulted in a decrease of approximately 17.621 Tg C a-1 in soil carbon storage. The findings of this study can help researchers understand China's carbon storage and provide scientific data to China's 2060 Carbon Neutrality Target.

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    Global Change Impact and Adaptation
    Experience and future research trends of wetland protection and restoration in China
    JIANG Weiguo, ZHANG Ze, LING Ziyan, DENG Yawen
    2023, 78 (9):  2223-2240.  doi: 10.11821/dlxb202309007
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    Wetland is an important natural resource for human beings and plays an irreplaceable ecological function in the terrestrial ecosystem. In order to curb the continued loss of wetlands around the world, international organizations and many countries have taken a series of major protection and restoration measures. This paper reviews the wetland protection and restoration measures of international organizations and some countries, comprehensively interprets China's wetland protection and restoration management experience, and proposes that future research on wetland resources should be carried out from the aspects of international frontier and national strategy, social economy and intelligent services. The results show that: (1) The 27 International Wetlands Day from 1997 to 2023 provide new goals and tasks for the protection and management of wetlands in corresponding years. The important topics and outcomes of the 14 International Convention on Wetlands Conferences from 1980 to 2022 provide new directions and new challenges for wetland development in the coming period. In the future, we should enhance ecological functions of wetlands, promote the sustainable development of wetlands, and overcome the technical bottleneck of ecological restoration of fragile wetland ecosystems from 2020 to 2035. (2) During the 30-year period from 1992 to 2022, China embarked on a new phase of wetland protection and restoration. The overall experience of wetland protection and restoration with Chinese characteristics has been formed through "national strategic deployment-legal policy establishment-project planning and implementation". Emphasis was placed on the need to provide for and prepare planning for the long-term protection of wetlands at the national legal level, to innovate restoration and management techniques and application systems, and to effectively address the complex issues of wetland protection and restoration through collaborative division of labor among multiple departments. (3) The research on the future trend of wetlands should be directed towards the exploration and practice of "United Nations Sustainable Development Goals and several international conventions" in support of the sustainable development of wetlands. Wetland protection, restoration and management services should be promoted for "national strategic needs and local social and economic high-quality development". Research on the cross-integration and academic innovation development also should be enhanced for "disciplinary development - global supervision - comprehensive assessment-intelligent decision-making".

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    Response of vegetation phenology to extreme climate and its mechanism
    ZHANG Jing, HAO Fanghua, WU Zhaofei, LI Mingwei, ZHANG Xuan, FU Yongshuo
    2023, 78 (9):  2241-2255.  doi: 10.11821/dlxb202309008
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    Global climate change caused by human activities results in frequent extreme climate events, and shifts the physiological processes of plants, and the carbon, water cycle and energy balance of terrestrial ecosystems. Vegetation phenology is the most sensitive biological indicator to climate change. In recent years, the responses of vegetation phenology to climate change mainly focus on the mean state of the climate, while the response mechanisms of vegetation phenology to extreme climate are still unclear. In this paper, the response of vegetation spring and autumn phenology to various extreme climatic events and their mechanisms were reviewed. We found that extreme low temperature and extreme precipitation directly delayed the vegetation green-up date and advanced the leaf senescence, while extreme high temperature and extreme drought led to stomatal closure, inhibited photosynthesis and transpiration, and thus advanced leaf senescence at middle and high latitudes of the Northern Hemisphere. Currently, the studies on the response of vegetation phenology to extreme climate events pay less attention to compound extreme climate events, and there are only few studies on the lag effect of vegetation phenology response to extreme climate events and the recovery process of vegetation after the occurrence of extreme events. Under future climate change scenarios, it is necessary to modify the vegetation phenological models by considering the impact of extreme climate events and couple it into the dynamic global vegetation models to improve the simulation accuracy of the carbon cycle in terrestrial ecosystems.

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    Topographic regulatory role of vegetation response to climate change
    XIONG Xueting, LI Chuanhua, CHEN Jiahao
    2023, 78 (9):  2256-2270.  doi: 10.11821/dlxb202309009
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    Topography largely contributes to the spatial heterogeneity of regional climate change and thus influences the response of vegetation to climate change. In this paper, using Three-River Headwaters Region of the Qinghai-Tibet Plateau as the study area, and structural equation modeling is utilized to explore the regulatory effect of topography factors on the Normalized Difference Vegetation Index through temperature and precipitation. The study shows that slope and aspect in the Three-River Headwaters Region mainly affect the response of vegetation to climate change by regulating precipitation, while elevation mainly affects the response of vegetation to climate change by regulating temperature. Elevation has the largest effect, which slows down the response of vegetation to climate change, with a total effect of -0.35; slope has the second largest effect, which intensifies the response of vegetation to climate change, with a total effect of 0.31; aspect has the smallest regulatory effect, with a total effect of 0.03; the total effect of topographic factors is -0.01, indicating that the three types of topographic factors have offsetting effects. In the Three-River Headwaters Region, the effect of topographic factors on vegetation regulation is the largest at slopes 5°-15°, shady slope and elevations 3000-3500 m, and their effects are 0.23, 0.08 and 0.39, respectively. At slopes 5°-15° and elevations 4500-5000 m, the aspect makes the vegetation respond to climate change the most by regulating precipitation; at slopes 5°-15°, shady slope and elevation lower than 4000 m, the elevation intensifies the vegetation response to climate by regulating temperature, and at elevation more than 4000 m, the elevation slows down the vegetation response to climate mainly by regulating precipitation. This paper can provide a basis for the study of the response pattern of mountain vegetation to climate change.

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    Modeling and validation of flash flood inundation in drylands
    GAO Dan, YIN Jie, WANG Dandan, YANG Yuhan, LU Yi, CHEN Ruishan
    2023, 78 (9):  2271-2283.  doi: 10.11821/dlxb202309010
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    In the context of climate change and human activities, flood disasters in arid mountainous areas become increasingly frequent, and the safety of people's lives and property has been seriously threatened. Rapid and accurate flash flood inundation modeling is an important and basic work to reduce casualties and disaster losses, and it is also a bottleneck problem that needs to be solved urgently in flash flood forecasting and warning. This paper aims to construct a numerical modeling method for flash flood in drylands. Based on a 2D high-resolution flood numerical model (FloodMap-HydroInundation2D), we hindcast the dynamic process of flash flooding and reveal the spatio-temporal characteristics of flash flood inundation for the "8.18" flash flood disaster that occurred in Datong county, Qinghai province. The results show that the model output agrees well with the observed inundation after the event, in terms of both spatial extent and temporal process. The extensive flooding mainly occurred between 00:00 and 1:00 on August 18, 2022. Qingshan, Hejiazhuang and Longwo villages are most heavily affected. We further conduct model sensitivity analysis and find that the model is highly sensitive to both roughness and hydraulic conductivity in drylands, and the effect of hydraulic conductivity is found to be more pronounced. This study confirms the good performance of the model for the simulation of flash flooding in arid areas, unlocking the potential for flash flood assessment and management in arid areas.

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    Spatio-temporal differences of enhanced aeolian sand activity in the northeastern Tibetan Plateau over the past 1500 years
    TANG Daobin, YANG Kunmei, ZENG Lanhua, LIU Xiangjun, XIN Cunlin, XU Yantian
    2023, 78 (9):  2284-2298.  doi: 10.11821/dlxb202309011
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    Based on previous studies, aeolian sand activity in northeastern Tibetan Plateau (NETP) had strengthened during the past 1500 years, but the reasons are still unknown, concerning climate change, human activities, or a combination of both. In this study, according to the natural environment and population distribution, the NETP is divided into two regions: Zone I, which mainly includes Qinghai Lake Basin, Gonghe Basin and Hehuang Valley, has better hydrothermal condition and the larger population than Zone II that is comprised of Yellow River source area and Qaidam Basin, with cold and dry climate and sparse population. Then, this paper summarizes the published ages of aeolian sand, aeolian sand activity records, paleoclimate proxy indicators and the related records of human activities in these two zones. Also, we analyze the spatio-temporal differences and influencing factors among the increasingly enhanced aeolian sand activity during the past 1500 years in the NETP. The results show that there are spatio-temporal differences of enhanced aeolian sand activity in the NETP over the past 1500 years. Aeolian sand activity in Zone I significantly strengthened during the relatively warm and humid period of 1.5~1.0 ka ago, while that in Zone II did not enhance until since 1.0 ka. The time when the aeolian sand activity began to strengthen in Zone I was 0.5 ka earlier than in Zone II. Through the comprehensive analysis, the study shows that the destruction of natural vegetation caused by increased human activities is the reason why the enhanced aeolian sand activity in Zone I was 0.5 ka earlier than that in Zone II. The enhanced aeolian sand activity in Zone II were mainly caused by climate change over the past 1.0 ka. This study provides an insight in the spatio-temporal differences of the enhanced aeolian sand activity in the NETP over the past 1500 years, as well as a reference for ecological environment governance and predicting the change of aeolian sand activity under the trend of global warming in the future.

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    Global Energy and World Regional Studies
    Energy transition reshapes geopolitics: Logic and research frontiers
    YANG Yu, XIA Siyou, JIN Zhijun
    2023, 78 (9):  2299-2315.  doi: 10.11821/dlxb202309012
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    The transition from fossil energy to renewable energy will change the structure of global energy geopolitical power structure, national relations, and the driving factors of geopolitical game, which will have a far-reaching impact on the geopolitical shaped by fossil energy. On the basis of combing the origin of energy and geopolitics, this paper expounds the internal logic of the energy transition to reconfigure geopolitics and provides an outlook on the geopolitics of the energy transition. The conclusions are as follows: (1) The connotation and attributes of energy, as well as the differences between energy and geopolitics, determine that energy geopolitics presents significant intergenerational transformation characteristics. (2) The competition for key minerals, the game of low-carbon technology, the reconstruction of geopolitical pattern and the global energy governance are the four dimensions of the geopolitics of energy transformation reconstruction, of which the competition for key minerals is the basis of the geopolitical game of energy transformation, the game of low-carbon technology is the new focus of the geopolitics of energy transformation, and the reconstruction of geopolitical pattern is the direct characterization of the geopolitics of energy transition, energy governance is the path to ease the geopolitical game of energy transformation. (3) In the process of energy transformation and reconstruction of geopolitics, the competition for key minerals, the game of low-carbon technology, the reconstruction of geopolitical pattern and global energy governance are interrelated and interacted, which aggravates the complexity and uncertainty of energy geopolitics in the era of renewable energy. (4) Looking forward to the future, to better promote the development of energy geography and serve the major strategic needs of national energy security, the geopolitical research of energy transformation urgently needs to strengthen the theoretical innovation of energy transition reshaping geopolitics, promote the quantitative research of the geopolitical impact of energy transformation, construct the path of China's deep participation in global energy governance, and pay attention to the energy security issues caused by energy transformation under the background of "carbon neutrality".

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    Spatio-temporal evolution and key drivers of global energy structural power
    ZHANG Qiang, DU Debin, GUO Weidong, YAN Ziming, CAO Wanpeng, XIA Qifan
    2023, 78 (9):  2316-2337.  doi: 10.11821/dlxb202309013
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    As a strategic resource, energy has become essential to national geopolitical strategies competition over energy structural power between states, and has implications for both their state power and energy security. Using the cross-country input-output data collected from the United Nations, we measure the structural power of energy in each country from 2001 through 2017. We evaluate the evolution of global structural power in energy through spatial structure, network, and the distribution of value added and identify the key drivers of its shift. The study shows that (1) The global energy structural power system was increasingly polarized and volatile and conflicts among energy superpowers gave rise to a big number of shatter belts. (2) We saw the rise of the East and the decline of the West in the trend of the global structural energy power, and China, the United States, and Germany are its major leading forces. Specifically, energy exporting power increasingly shifted to China, whereas energy importing power was further centered in West Europe and North America. (3) The associations of global structural engergy power saw both shrinkage and diffusion: they expanded their coverage in the Asia-Pacific and Eastern Europe whereas decreased their coverage in Western Europe and the United States. (4) The hierarchical order of global energy structural power gradually shifed from dual cores, triple cores, to mutiple cores, and the relationship between different hierarchical orders changed drastically. (5) As for the core chain of energy value flow, energy structural superpowers represented by Germany and the United States led the chain and dominated the distribution of energy value, while small nations in energy production serve as followers and subordinates were stuck in low-end industries. The sections of the energy industrial chain exhibited a U-shaped curve in which energy exploration, mining, processing perform relatively high values, whereas transportation and storage produce relatively low values. (6) The key drivers of national energy structural power gradually shifted from early energy endowment and energy trades to market capitals. We propose corresponding policy advice that fosters the consolidation of China's structural energy power.

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    Research on the coupling coordination between the scale of China's overseas farmland investment and geo-economy
    PAN Zichun, MA Linyan, ZHU Yuchun
    2023, 78 (9):  2338-2357.  doi: 10.11821/dlxb202309014
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    Exploring the spatial differentiation and driving factors of the coupling coordination between the scale of China's overseas farmland investment and geo-economy can provide a reference for Chinese enterprises to scientifically implement overseas farmland investment activities. This paper establishes a system to evaluate China's overseas farmland investment scale and geo-economy, measure the degree of coupling coordination between the two using the coupling coordination model, and analyze the spatial differentiation characteristics and driving factors. The results show that: (1) The scale of China's overseas farmland investment and the geo-economic ties between China and each host country are highly decentralized, with the regions having a higher investment scale and closer geo-economy located in Russia and Southeast Asia. (2) The coupling coordination degree of investment scale and geo-economy is significantly and positively correlated, and strong spatial differentiation has been observed in certain localities. The high-high agglomeration is distributed in Southeast Asia. (3) The coupling coordinated development is heavily influenced by six factors, including the ease of doing business index, GDP, per capita freshwater resource ownership, cereal yield, internet ownership of millions of people and legal rights strength index. (4) The effects of six factors, namely the ease of doing business index, GDP, per capita freshwater resource ownership, cereal yield, internet ownership of millions of people and legal rights strength index, has spatial differences and enhanced interaction effects. Among them, the enhancement effect value produced by GDP and any factor is more obvious. The following four aspects should be considered to strengthen the coupling coordination development of overseas farmland investment and geo-economy: optimizing the spatial pattern between the two, exploring regional differentiation paths, improving strategic planning and considering the factors influencing the promotion of the coupling coordination.

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    Historical geographical evolution in Ladakh region
    ZHANG Xiaohong, CHEN Hao, HUANG Yu, XU Jianping, CHEN Fahu
    2023, 78 (9):  2358-2372.  doi: 10.11821/dlxb202309015
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    Ladakh is located in the northwest of the Qinghai-Tibet Plateau, the western section of the Himalayas, and the upper reaches of the Indus River valley. It is now part of Indian-controlled Kashmir. Since ancient times, Ladakh has been the "key point" from northwest South Asia to the Ngari Prefecture of Xizang and southern Xinjiang. However, most existing research on Ladakh focuses on its local history and culture. Although there are some related works on geopolitical relations, few have studied the historical changes of this region and its subordinate relationship and geographical value with China over a long time scale and analyzed the geographical significance of Ladakh. At the same time, some erroneous views and geographical maps have been disseminated on the Internet at home and abroad, which urgently needs a comprehensive correction from the academic level. Based on a variety of historical documents, map data, and a detailed review of previous research results, this paper demonstrates the changes in place names, historical evolution, and regional scope of Ladakh from the 1st to the 21st century and analyzes its significance in the homeland security of western China. The results show that: (1) As the native land of China's Xizang Ladakh was part of the Tubo Dynasty until the 9th century. After the collapse of the Tubo Dynasty in the middle of the 9th century, Ladakh was an essential part of the Ngari local administration established by the descendants of the Tubo Royal family. In the 13th century, Ladakh was again united within the territory of China's Yuan Dynasty and continued through the Ming and Qing dynasties. It remained until the mid-19th century when the Prince-state of Jammu in southern Kashmir invaded it and incorporated it into the British Indian colony. It was then occupied by the Indian army in 1947. (2) Ladakh region has a tortuous history with many changes in place names. However, when Jammu annexed it in modern times, Ladakh only referred to the upper reaches of Indus Valley between the Western Himalayas and the Karakoram Mountains, with Leh as the center. (3) The complexity of the historical and geographical processes in the Ladakh region makes it the central area of conflicts created by India in the western section of the China-India border. Therefore, China should adopt active strategies to avoid India's continuous "assimilation" policy.

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