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    Progress in watershed geography in the Yangtze River Basin and the affiliated ecological security perspective in the past 20 years, China
    GAO Yang, JIA Junjie, LU Yao, SUN Xiaomin, WEN Xuefa, HE Nianpeng, YANG Tiantian
    Journal of Geographical Sciences    2020, 30 (6): 867-880.   doi: 10.1007/s11442-020-1759-y
    Abstract286)   HTML19)    PDF (1720KB)(38)      

    Bibliometrics was used to statistically analyze key zones within the Yangtze River Basin (YRB) funded by the National Natural Science Foundation of China (NSFC) and national ministries over the past 20 years. This study determined that funds that derived from national ministries have mainly focused on issues related to environmental pollution, ecological security, technological water regulations, and river basin ecosystems, which offer a better understanding of the national requirements and the scientific knowledge of the YRB in combination with data from the NSFC. Under a background of bolstering the construction of green ecological corridors in the economic belt of the YRB, this study proposes future conceptual watershed research initiatives in this region as a study objective by reinforcing the implementation of the Chinese Ecosystem Research Network (CERN) and by emphasizing the use of new technologies, new methods, and new concepts for the prospective design of frontier research under the perspective of geoscience and earth system science. This study promotes large-scale scientific field and research objectives based on big science and big data.

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    Exploring global food security pattern from the perspective of spatio-temporal evolution
    CAI Jianming, MA Enpu, LIN Jing, LIAO Liuwen, HAN Yan
    Journal of Geographical Sciences    2020, 30 (2): 179-196.   doi: 10.1007/s11442-020-1722-y
    Abstract220)   HTML17)    PDF (940KB)(84)      

    Food security is the primary prerequisite for achieving other Millennium Development Goals (MDGs). Given that the MDG of “halving the proportion of hungers by 2015” was not realized as scheduled, it will be more pressing and challenging to reach the goal of zero hunger by 2030. So there is high urgency to find the pattern and mechanism of global food security from the perspective of spatio-temporal evolution. In this paper, based on the analysis of database by using a multi-index evaluation method and radar map area model, the global food security level for 172 countries from 2000 to 2014 were assessed; and then spatial autocorrelation analysis was conducted to depict the spatial patterns and changing characteristics of global food security; then, multi-nonlinear regression methods were employed to identify the factors affecting the food security patterns. The results show: 1) The global food security pattern can be summarized as “high-high aggregation, low-low aggregation”. The most secure countries are mainly distributed in Western Europe, North America, Oceania and parts of East Asia. The least secure countries are mainly distributed in sub-Saharan Africa, South Asia and West Asia, and parts of Southeast Asia. 2) Europe and sub-Saharan Africa are hot and cold spots of the global food security pattern respectively, while in non-aggregation areas, Haiti, North Korea, Tajikistan and Afghanistan have long-historical food insecurity problems. 3) The pattern of global food security is generally stable, but the internal fluctuations in the extremely insecure groups were significant. The countries with the highest food insecurity are also the countries with the most fluctuated levels of food security. 4) The annual average temperature, per capita GDP, proportion of people accessible to clean water, political stability and non-violence levels are the main factors influencing the global food security pattern. Research shows that the status of global food security has improved since the year 2000, yet there are still many challenges such as unstable global food security and acute regional food security issues. It will be difficult to understand these differences from a single factor, especially the annual average temperature and annual precipitation. The abnormal performance of the above factors indicates that appropriate natural conditions alone do not absolutely guarantee food security,while the levels of agricultural development, the purchasing power of residents, regional accessibility, as well as political and economic stability have more direct influence.

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    Beautiful China Initiative: Human-nature harmony theory, evaluation index system and application
    FANG Chuanglin, WANG Zhenbo, LIU Haimeng
    Journal of Geographical Sciences    2020, 30 (5): 691-704.   doi: 10.1007/s11442-020-1750-7
    Abstract194)   HTML5)    PDF (3207KB)(15)      

    The Beautiful China Initiative (BCI) is a plan for the sustainable development of the Chinese nation as well as for China to fulfill the United Nations’ 2030 Agenda for Sustainable Development. The Chinese government’s “five-in-one” approach provides strategic arrangements for developing the BCI, and President Xi Jinping proposed a timetable and “road map” for the BCI at the National Conference on Ecological and Environmental Protection. Nevertheless, the theoretical basis, evaluation index system, evaluation criteria and effectiveness of the BCI are currently unclear. This paper begins by exploring the basic content of the BCI from narrow and broad perspectives. It regards the theory of human-nature harmonious coexistence and the five-in-one beauty theory as the core theoretical bases of the BCI and constructs a five-element BCI evaluation index system (ecological environment, green development, social harmony, system perfection and cultural heritage) and utilizes the assessment method of the United Nations’ Human Development Index to assess scientifically the effectiveness of the BCI in 341 prefecture-level cities. The results show the average BCI index (the Chinese Academy of Sciences Beauty Index) score to be 0.28, which is quite low, while the average scores for the individual element indexes of the ecological environment index, green development index, social harmony index, system perfection index and cultural heritage index are 0.6, 0.22, 0.29, 0.22 and 0.07, respectively. All of these are relatively low values, with relatively large discrepancies in regional development, indicating that progress in the BCI is generally slow and unbalanced. To realize the BCI’s timetable and roadmap to a high quality and high standard, it is suggested that a common system for evaluating the progress of the BCI is developed and promulgated so that dynamic monitoring and phased evaluations can take place; BCI technical assessment standards are compiled and published; BCI comprehensive zoning is undertaken; pilot projects adapted to local conditions are launched in BCI sample areas; and BCI results are incorporated into performance indicators at all levels of government.

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    Geomorphological regionalization theory system and division methodology of China
    WANG Nan, CHENG Weiming, WANG Baixue, LIU Qiangyi, ZHOU Chenghu
    Journal of Geographical Sciences    2020, 30 (2): 212-232.   doi: 10.1007/s11442-020-1724-9
    Abstract168)   HTML6)    PDF (702KB)(35)      

    Geomorphological regionalization (geomor-region) and geomorphological type (geomor-type) classification are two core components in the geomorphologic research. Although remarkable achievements have been made in the study of geomor-region, many deficiencies still exist, such as the inconsistency of landform indicators, the small quantity of division orders, disparities of geomorphological characteristics, differences of mapping results, and the small scale of zoning maps. Requirements for improved national geomor-regions are therefore needed for the purpose of an enhanced national geo-information system. Based on theories of geomor-region in China including plate tectonics, crustal features, endogenic and exogenic forced geomorphological features, and regional differentiations of geomor-type, a three-order (major-region, sub-region, and small-region) research program on China’s geomor-regions is proposed on the basis of previous 2013 geomor-region system. The major contents of the new geomor-region scheme are: (1) principles of the national multi-order geomor-regions; (2) hierarchical indicator systems of geomor-regions including characteristics of the terrain ladder under the control of tectonic setting, combinations of regional macro-form types, combinations of endogenic and exogenic forces and basic types of morphology, combinations of regional morphological types, and combinations of regional micro-morphological types; (3) naming rules and coding methods of geomor-regions; and (4) precise positioning techniques and methods of multi-order geomor-region divisions based on multi-source data. Using the new geomor-region theory and division methodology, the partition of national three-order geomor-regions of China was successfully constructed. The geomor-region system divided China into six first-order major-regions, 36 second-order sub-regions, and 136 third-order small-regions. In addition, a database and management information system of the national geomor-regions were established. This research has an important guiding significance for promoting the development of China’s regional geomorphology and for practical applications based on geomor-regions.

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    Multi-scale analysis of the spatial structure of China’s major function zoning
    WANG Yafei, FAN Jie
    Journal of Geographical Sciences    2020, 30 (2): 197-211.   doi: 10.1007/s11442-020-1723-x
    Abstract167)   HTML13)    PDF (2054KB)(40)      

    The spatial structures of China’s Major Function Zoning are important constraining indicators in all types of spatial planning and key parameters for accurately downscaling major functions. Taking the proportion of urbanization zones, agricultural development zones and ecological security zones as the basic parameter, this paper explores the spatial structures of major function zoning at different scales using spatial statistics, spatial modeling and landscape metrics methods. The results show: First, major function zones have spatial gradient structures, which are prominently represented by latitudinal and longitudinal gradients, a coastal distance gradient, and an eastern-central-western gradient. Second, the pole-axis system structure and core-periphery structure exist at provincial scales. The general principle of the pole-axis structure is that as one moves along the distance axis, the proportion of urbanization zones decreases and the proportion of ecological security zones increases. This also means that the proportion of different function zones has a ring-shaped spatial differentiation principle with distance from the core. Third, there is a spatial mosaic structure at the city and county scale. This spatial mosaic structure has features of both spatial heterogeneity, such as agglomeration and dispersion, as well as of mutual, adjacent topological correlation and spatial proximity. The results of this study contribute to scientific knowledge on major function zones and the principles of spatial organization, and it acts as an important reference for China’s integrated geographical zoning.

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    Urban expansion patterns and their driving forces based on the center of gravity-GTWR model: A case study of the Beijing-Tianjin-Hebei urban agglomeration
    WANG Haijun, ZHANG Bin, LIU Yaolin, LIU Yanfang, XU Shan, ZHAO Yuntai, CHEN Yuchen, HONG Song
    Journal of Geographical Sciences    2020, 30 (2): 297-318.   doi: 10.1007/s11442-020-1729-4
    Abstract158)   HTML3)    PDF (3653KB)(28)      

    Research into urban expansion patterns and their driving forces is of great significance for urban agglomeration development planning and decision-making. In this paper, we reveal the multi-dimensional characteristics of urban expansion patterns, based on the intensity index of the urban expansion, the differentiation index of the urban expansion, the fractal dimension index, the land urbanization rate, and the center of gravity model, by taking the Beijing-Tianjin-Hebei (Jing-Jin-Ji) urban agglomeration as an example. We then build the center of gravity-geographically and temporally weighted regression (GTWR) model by coupling the center of gravity model with the GTWR model. Through the analysis of the temporal and spatial patterns and by using the center of gravity-GTWR model, we analyze the driving forces of the urban land expansion and summarize the dominant development modes and core driving forces of the Jing-Jin-Ji urban agglomeration. The results show that: 1) Between 1990 and 2015, the expansion intensity of the Jing-Jin-Ji urban agglomeration showed a down-up-down trend, and the peak period was in 2005-2010. Before 2005, high-speed development took place in Beijing, Tianjin, Baoding, and Langfang; after 2005, rapid development was seen in Xingtai and Handan. 2) Although the barycenter of cities in the Jing-Jin-Ji urban agglomeration has shown a divergent trend, the local interaction between cities has been enhanced, and the driving forces of urban land expansion have shown a characteristic of spatial spillover. 3) The spatial development mode of the Jing-Jin-Ji urban agglomeration has changed from a dual-core development mode to a multi-core development mode, which is made up of three functional cores: the transportation core in the northern part, the economic development core in the central part, and the investment core in the southern part. The synergistic development between each functional core has led to the multi-core development mode. 4) The center of gravity-GTWR model combines the analysis of spatial and temporal nonstationarity with urban spatial interaction, and analyzes the urban land expansion as a space-time dynamic system. The results of this study show that the model is a feasible approach in the analysis of the driving forces of urban land expansion.

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    Spatio-temporal variation in China’s climatic seasons from 1951 to 2017
    MA Bin, ZHANG Bo, JIA Lige
    Journal of Geographical Sciences    2020, 30 (9): 1387-1400.   doi: 10.1007/s11442-020-1788-6
    Abstract154)   HTML2)    PDF (2155KB)(96)      

    In this paper, meteorological industry standard, daily mean temperature, and an improved multiple regression model are used to calculate China’s climatic seasons, not only to help understand their spatio-temporal distribution, but also to provide a reference for China’s climatic regionalization and crop production. It is found that the improved multiple regression model can accurately show the spatial distribution of climatic seasons. The main results are as follows. There are four climatic seasonal regions in China, namely, the perennial-winter, no-winter, no-summer and discernible regions, and their ranges basically remained stable from 1951 to 2017. The cumulative anomaly curve of the four climatic seasonal regions clarifies that the trend of China’s climatic seasonal regions turned in 1994, after which the area of the perennial-winter and no-summer regions narrowed and the no-winter and discernible regions expanded. The number of sites with significantly reduced winter duration is the largest, followed by the number of sites with increased summer duration, and the number of sites with large changes in spring and autumn is the least. Spring advances and autumn is postponed due to the shortened winter and lengthened summer durations. Sites with significant change in seasonal duration are mainly distributed in Northwest China, the Sichuan Basin, the Huanghe-Huaihe-Haihe (Huang-Huai-Hai) Plain, the Northeast China Plain, and the Southeast Coast.

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    Application of an evaluation method of resource and environment carrying capacity in the adjustment of industrial structure in Tibet
    NIU Fangqu, YANG Xinyu, ZHANG Xiaoping
    Journal of Geographical Sciences    2020, 30 (2): 319-332.   doi: 10.1007/s11442-020-1730-y
    Abstract150)   HTML3)    PDF (593KB)(17)      

    With the degradation of natural resources and environment caused by industrial development in some developing countries, the requirement of implementing a “social ecological” approach to development is imminent. Resource and environment carrying capacity provides a means of assessing regional development potential by measuring regional sustainable development in terms of economy, population and resources & environment. This study develops a conceptual framework for resource and environment carrying capacity estimation to support the co-development planning of industries, population and resources & environment. First, the framework constructs an index system for evaluating importance of industry or influence based on the role of industry played in the local socio-economic system. Then, the framework computes the quantitative relations through the importance of local industry, population size and resource utilization and environment effects, and subsequently estimates the resource and environment carrying capacity of the study area. With a particular attention to its land resources, water resources and environment, the Tibet case study shows that: the non-ferrous metal mining, tourism, liquor and refined tea industries play a pillar role in the Tibet’s socio-economic system; under each industrial structure, land resource carrying capacity is the weakest, and water resources carrying capacity is the strongest; to focus on tourism will improve local resource and environment carrying capacity. The research results provide a solid guide for Tibet government’s co-actions in industrial restructuring, ecological protection, and the pursuit of economic development. This study will contribute to bridge the gap between theoretical research and practical applications of resource and environment carrying capacity, and help local governments plan the regional “socio-ecological” sustainable development.

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    Compilation of 1:50,000 vegetation type map with remote sensing images based on mountain altitudinal belts of Taibai Mountain in the North-South transitional zone of China
    YAO Yonghui, SUONAN Dongzhu, ZHANG Junyao
    Journal of Geographical Sciences    2020, 30 (2): 267-280.   doi: 10.1007/s11442-020-1727-6
    Abstract147)   HTML6)    PDF (4024KB)(21)      

    The compilation of 1:250,000 vegetation type map in the North-South transitional zone and 1:50,000 vegetation type maps in typical mountainous areas is one of the main tasks of Integrated Scientific Investigation of the North-South Transitional Zone of China. In the past, vegetation type maps were compiled by a large number of ground field surveys. Although the field survey method is accurate, it is not only time-consuming, but also only covers a small area due to the limitations of physical environment conditions. Remote sensing data can make up for the limitation of field survey because of its full coverage. However, there are still some difficulties and bottlenecks in the extraction of remote sensing information of vegetation types, especially in the automatic extraction. As an example of the compilation of 1:50,000 vegetation type map, this paper explores and studies the remote sensing extraction and mapping methods of vegetation type with medium and large scales based on mountain altitudinal belts of Taibai Mountain, using multi-temporal high resolution remote sensing data, ground survey data, previous vegetation type map and forest survey data. The results show that: 1) mountain altitudinal belts can effectively support remote sensing classification and mapping of 1:50,000 vegetation type map in mountain areas. Terrain constraint factors with mountain altitudinal belt information can be generated by mountain altitudinal belts and 1:10,000 Digital Surface Model (DSM) data of Taibai Mountain. Combining the terrain constraint factors with multi-temporal and high-resolution remote sensing data, ground survey data and previous small-scale vegetation type map data, the vegetation types at all levels can be extracted effectively. 2) The basic remote sensing interpretation and mapping process for typical mountains is interpretation of vegetation type-groups→interpretation of vegetation formation groups, formations and subformations→interpretation and classification of vegetation types & subtypes, which is a combination method of top-down method and bottom-up method, not the top-down or the bottom-up classification according to the level of mapping units. The results of this study provide a demonstration and scientific basis for the compilation of large and medium scale vegetation type maps.

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    Geographical thoughts on the relationship between ‘Beautiful China’ and land spatial planning
    CHEN Mingxing, LIANG Longwu, WANG Zhenbo, ZHANG Wenzhong, YU Jianhui, LIANG Yi
    Journal of Geographical Sciences    2020, 30 (5): 705-723.   doi: 10.1007/s11442-020-1751-6
    Abstract146)   HTML4)    PDF (1926KB)(22)      

    The concept of ‘Beautiful China’ is a new goal of ecological construction in the new era of socialism and aims to meet the needs of people as they strive for a better life. National land spatial planning is one major component of the Chinese state’s overall planning for various spatial types. The concept of ‘Beautiful China’ is thus a leading goal of Chinese development in the second centenary. The background of this concept aims for ‘ecological beauty’ as well as the combined beauty of ‘economy-politics-culture-society-ecology.’ The construction of ‘Beautiful China’ therefore necessitates a differentiated evaluation index system that is built on the basis of local conditions. This concept is intimately related to land spatial planning and the idea of Beautiful China guides an important direction for this planning which itself provides an important mechanism and spatial guarantee for construction. The establishment of land spatial planning nevertheless needs to strengthen further discussion of the regional system of human-land relationship, point axis system, main functional division, sustainable development, resources and environmental carrying capacity as well as new urbanization, and the rural multi-system. The aim of this paper is to summarize current thinking in land spatial planning, scientifically analyze the natural geographical conditions, the socioeconomic development, the interrelationship of the land space, plan the goal, vision and path of land space, encourage the public to participate in and carry out dynamic evaluation, build an intelligent system platform for land and spatial planning to realize the goal of ‘Beautiful China’ from a geographical perspective. And they can also present key ideas relating to the compilation and implementation of land spatial planning.

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    Spatio-temporal evolution and influencing factors of urban green development efficiency in China
    ZHOU Liang, ZHOU Chenghu, CHE Lei, WANG Bao
    Journal of Geographical Sciences    2020, 30 (5): 724-742.   doi: 10.1007/s11442-020-1752-5
    Abstract144)   HTML2)    PDF (876KB)(14)      

    To resolve conflicts between development and the preservation of the natural environment, enable economic transformation, and achieve the global sustainable development goals (SDGs), green development (GD) is gradually becoming a major strategy in the construction of an ecological civilization and the ideal of building a “beautiful China”, alongside the transformation and reconstruction of the global economy. Based on a combination of the concept and implications of GD, we first used the Slacks Based Model with undesirable outputs (SBM-Undesirable), the Theil index, and the spatial Markov chain to measure the spatial patterns, regional differences, and spatio-temporal evolution of urban green development efficiency (UGDE) in China from 2005 to 2015. Second, by coupling natural and human factors, the mechanism influencing UGDE was quantitatively investigated under the framework of the human-environment interaction. The results showed that: (1) from 2005 to 2015, the UGDE increased from 0.475 to 0.523, i.e., an overall increase of 10%. In terms of temporal variation, there was a staged increase, with its evolution having the characteristics of a “W-shaped” pattern. (2) The regional differences in UGDE followed a pattern of eastern > central > western. For different types of urban agglomeration, the UGDE had inverted pyramid cluster growth characteristics that followed a pattern of “national level > regional level > local level”, forming a stable hierarchical scale structure of “super cities > mega cities > big cities > medium cities > small cities”. (3) UGDE in China has developed with significant spatial agglomeration characteristics. High-efficiency type cities have positive spillover effects, while low-efficiency cities have negative effects. Different types of urban evolution processes have a path dependence, and a spatial club convergence phenomenon exists, in which areas with high UGDE are concentrated and drive low UGDE elsewhere. (4) Under the framework of regional human-environment interaction, the degree of human and social influence on UGDE is greater than that of the natural background. The economic strength, industrial structure, openness, and climate conditions of China have positively promoted UGDE.

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    From earth observation to human observation: Geocomputation for social science
    LI Deren, GUO Wei, CHANG Xiaomeng, LI Xi
    Journal of Geographical Sciences    2020, 30 (2): 233-250.   doi: 10.1007/s11442-020-1725-8
    Abstract143)   HTML2)    PDF (4509KB)(17)      

    It is possible to obtain vast amounts of spatiotemporal data related to human activities to support the study of human behavior and social evolution. In this context, geography, with the human-nature relationship as its core, is undergoing a transition from strictly earth observations to the observation of human activities. Geocomputation for social science is one manifestation thereof. Geocomputation for social science is an interdisciplinary approach combining remote sensing techniques, social science, and big data computation. Driven by the availability of spatially and temporally expansive big data, geocomputation for social science uses spatiotemporal statistical analyses to detect and analyze the interactions between human behavior, the natural environment, and social activities; Remote sensing (RS) observations are used as primary data. Geocomputation for social science can be used to investigate major social issues and to assess the impact of major natural and societal events, and will surely be an area of focused development in geography in the near future. We briefly review the background of geocomputation in the social sciences, discuss its definition and disciplinary characteristics, and highlight the main research foci. Several key technologies and applications are also illustrated with relevant case studies of the Syrian Civil War, typhoon transits, and traffic patterns.

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    Spatiotemporal evolution of urban carbon emission performance in China and prediction of future trends
    WANG Shaojian, GAO Shuang, HUANG Yongyuan, SHI Chenyi
    Journal of Geographical Sciences    2020, 30 (5): 757-774.   doi: 10.1007/s11442-020-1754-3
    Abstract141)   HTML0)    PDF (1602KB)(6)      

    Climate change resulting from CO2 emissions has become an important global environmental issue in recent years. Improving carbon emission performance is one way to reduce carbon emissions. Although carbon emission performance has been discussed at the national and industrial levels, city-level studies are lacking due to the limited availability of statistics on energy consumption. In this study, based on city-level remote sensing data on carbon emissions in China from 1992-2013, we used the slacks-based measure of super-efficiency to evaluate urban carbon emission performance. The traditional Markov probability transfer matrix and spatial Markov probability transfer matrix were constructed to explore the spatiotemporal evolution of urban carbon emission performance in China for the first time and predict long-term trends in carbon emission performance. The results show that urban carbon emission performance in China steadily increased during the study period with some fluctuations. However, the overall level of carbon emission performance remains low, indicating great potential for improvements in energy conservation and emission reduction. The spatial pattern of urban carbon emission performance in China can be described as “high in the south and low in the north,” and significant differences in carbon emission performance were found between cities. The spatial Markov probabilistic transfer matrix results indicate that the transfer of carbon emission performance in Chinese cities is stable, resulting in a “club convergence” phenomenon. Furthermore, neighborhood backgrounds play an important role in the transfer between carbon emission performance types. Based on the prediction of long-term trends in carbon emission performance, carbon emission performance is expected to improve gradually over time. Therefore, China should continue to strengthen research and development aimed at improving urban carbon emission performance and achieving the national energy conservation and emission reduction goals. Meanwhile, neighboring cities with different neighborhood backgrounds should pursue cooperative economic strategies that balance economic growth, energy conservation, and emission reductions to realize low-carbon construction and sustainable development.

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    Dynamic simulation of urbanization and eco-environment coupling: Current knowledge and future prospects
    CUI Xuegang, FANG Chuanglin, LIU Haimeng, LIU Xiaofei, LI Yonghong
    Journal of Geographical Sciences    2020, 30 (2): 333-352.   doi: 10.1007/s11442-020-1731-x
    Abstract130)   HTML1)    PDF (390KB)(23)      

    Urbanization and eco-environment coupling is a research hotspot. Dynamic simulation of urbanization and eco-environment coupling needs to be improved because the processes of coupling are complex and statistical methods are limited. Systems science and cross-scale coupling allow us to define the coupled urbanization and eco-environment system as an open complex giant system with multiple feedback loops. We review the current state of dynamic simulation of urbanization and eco-environment coupling and find that: (1) The use of dynamic simulation is an increasing trend, the relevant theory is being developed, and modeling processes are being improved; (2) Dynamic simulation technology has become diversified, refined, intelligent and integrated; (3) Simulation is mainly performed for three aspects of the coupling, multiple regions and multiple elements, local coupling and telecoupling, and regional synergy. However, we also found some shortcomings: (1) Basic theories are inadequately developed and insufficiently integrated; (2) The methods of unifying systems and sharing data are behind the times; (3) Coupling relations and the dynamic characteristics of the main driving elements are not fully understood or completely identified. Additionally, simulation of telecoupling does not quantify parameters and is not systemically unified, and therefore cannot be used to represent spatial synergy. In the future, we must promote communication between research networks, technology integration and data sharing to identify the processes governing change in coupled relations and in the main driving elements in urban agglomerations. Finally, we must build decision support systems to plan and ensure regional sustainable urbanization.

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    Traditional agroecosystem transition in mountainous area of Three Gorges Reservoir Area
    LIANG Xinyuan, LI Yangbing, SHAO Jing’an, RAN Caihong
    Journal of Geographical Sciences    2020, 30 (2): 281-296.   doi: 10.1007/s11442-020-1728-5
    Abstract125)   HTML1)    PDF (4366KB)(27)      

    The Three Gorges Reservoir Area (TGRA) is typical of an ecologically vulnerable area, comprised of rural and mountainous areas, and with high immigration. Because of its economic and ecologic importance, studying the traditional agroecosystem changes in the TGRA is key to rural development and revitalization. In this study, we apply a framework of theoretical analysis, empirical study, and trend prediction to the Caotangxi River watershed within the TGRA. Using QuickBird high-resolution remote sensing images from 2012 to 2017 to evaluate natural resources and farmers’ behavior, we analyze the transition and trends in the traditional agroecosystem in mountainous areas of the TGRA at spatial scale of the man-land relationship. We find that the agroecosystem in the TGRA can be divided into four modes using 100 m interval buffer rings: high-low-low, high-low-high, low-high-low and low-low-high mode where the different modes represent the agricultural development stages in the TGRA. Furthermore, the traditional agroecosystem in TGRA, represented by system elements such as farmers and sloping farmland, is transforming to accommodate the diversification of farmer livelihoods. For example, sloping farmland, which was dominated by a production function, now has equal emphasis on ecological and economic functions. Spatially, the range of the agroecosystem transition has migrated beyond high mountain areas to flat valley areas. Generally, this study provides an overview of land use in rural areas, controls on soil and water loss in mountainous areas, and better rural living environments in the TGRA.

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    Spatio-temporal pattern and driving forces of urbanization in China’s border areas
    SONG Zhouying, ZHU Qiaoling
    Journal of Geographical Sciences    2020, 30 (5): 775-793.   doi: 10.1007/s11442-020-1755-2
    Abstract121)   HTML5)    PDF (2274KB)(13)      

    Border area is not only an important gateway for inland opening-up, but also an important part of completing the building of a moderately prosperous society and optimizing national urban spatial pattern in China. Due to the location, natural resources endowment, and traffic accessibility, the urbanization speed is relatively slow in border areas. Therefore, it is a special area that needs to pay close attention to, especially under the background of the Belt and Road Initiative and China’s regional coordinated development program. Based on the county-level data from 2000 to 2015, this paper tries to analyze the spatio-temporal pattern of urbanization in 134 border counties, and applies geographical detector method to study the driving forces of urbanization in border areas. Conclusions are as follows: (1) From 2000 to 2015, urbanization rate in border areas has been lower than the national average, and the gap has been widening. Some border counties in southern Xinjiang, Tibet, northeast of Inner Mongolia, and Yunnan, are even facing the problem of population loss. (2) In the same period, urbanization rate in the northwestern and southwestern border is low, while their urbanization rate grows relatively faster comparing with other border counties; urbanization rate in Tibet border is the lowest and grows relatively slowly; urbanization rate in the northeastern and northern border is slightly higher, but it grows slowly or even stagnates. (3) Transportation and industry are the important driving forces of urbanization in border areas, while the driving forces of market is relatively weak. And there are obvious mutual reinforcements among the driving forces, while the effort and explanatory power of resource force increases obviously after interaction. (4) Urbanization rate in the northwestern and southwestern border areas grows relatively fast, with industrial force and transportation force, market force and administrative force as the main driving forces respectively. Tibet border area has the lowest urbanization rate and growth rate, as the driving force of urbanization with strong contribution has not yet formed in Tibet. In the northeastern and northern border areas, the contribution of transportation force to urbanization is greater than other forces, and its interaction with market and industry has obvious effects.

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    A comparative study of land price estimation and mapping using regression kriging and machine learning algorithms across Fukushima prefecture, Japan
    Journal of Geographical Sciences    2020, 30 (5): 794-822.   doi: 10.1007/s11442-020-1756-1
    Abstract112)   HTML2)    PDF (8028KB)(11)      

    Finding accurate methods for estimating and mapping land prices at the macro-scale based on publicly accessible and low-cost spatial data is an essential step in producing a meaningful reference for regional planners. This asset would assist them in making economically justified decisions in favor of key investors for development projects and post-disaster recovery efforts. Since 2005, the Ministry of Land, Infrastructure, and Transport of Japan has made land price data open to the public in the form of observations at dispersed locations. Although this data is useful, it does not provide complete information at every site for all market participants. Therefore, estimating and mapping land prices based on sound statistical theories is required. This paper presents a comparative study of spatial prediction of land prices in 2015 in Fukushima prefecture based on geostatistical methods and machine learning algorithms. Land use, elevation, and socioeconomic factors, including population density and distance to railway stations, were used for modeling. Results show the superiority of the random forest algorithm. Overall, land prices are distributed unevenly across the prefecture with the most expensive land located in the western region characterized by flat topography and the availability of well-connected and highly dense economic hotspots.

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    Analysis of critical river discharge for saltwater intrusion control in the upper South Branch of the Yangtze River Estuary
    SUN Zhaohua, FAN Jiewei, YAN Xin, XIE Cuisong
    Journal of Geographical Sciences    2020, 30 (5): 823-842.   doi: 10.1007/s11442-020-1757-0
    Abstract111)   HTML0)    PDF (1785KB)(7)      

    Saltwater intrusion in the estuary area threatens the use of freshwater resources. If river discharge increases to a critical value, then saltwater intrusion frequency and salinity level decreases. In this study, long-term river discharge and tidal range data in the Yangtze River Estuary (YRE) and salinity data obtained in the upper South Branch of the YRE were used to analyze the characteristics of different variables and the basic law of their interactions. Two methods, namely, the material analysis method and empirical models, were applied to determine the critical river discharge for saltwater intrusion control. Results are as follows: (1) the salinity might exceed the drinking water standard of China when the river discharge was less than 30,000 m3/s. Approximately 69% of salinity excessive days occurred when the river discharge was less than 15,000 m3/s; (2) the tidal range in the YRE roughly varied in sinusoidal pattern with a 15-day cycle length. Exponential relationship existed between daily salinity (chlorinity) and daily mean tidal range. Combining these two features with the cumulative frequency statistics of tidal ranges, it was showed that notable saltwater intrusion occurred when the tidal range was more than 2.7 m at Qinglonggang station. Moreover, the critical discharge was found to be slightly higher than 11,000 m3/s; (3) various of empirical models for salinity prediction could be chosen to calculate the critical discharge. The values obtained by different models were in the range of 11,000-12,000 m3/s; (4) the proposed critical discharge to reduce notable saltwater intrusion was 11,500 m3/s. After the Three Gorges Reservoir operation, the minimum river discharge into the YRE in 2008-2017 was below the critical discharge, thereby suggesting an increase in the minimum river discharge by reservoir regulation in drought periods.

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    Agent-based model of land system: Theory, application and modelling framework
    DAI Erfu, MA Liang, YANG Weishi, WANG Yahui, YIN Le, TONG Miao
    Journal of Geographical Sciences    2020, 30 (10): 1555-1570.   doi: 10.1007/s11442-020-1799-3
    Abstract107)   HTML23)    PDF (919KB)(97)      

    Land change science has become an interdisciplinary research direction for understanding human-natural coupling systems. As a process-oriented modelling approach, agent based model (ABM) plays an important role in revealing the driving forces of land change and understanding the process of land change. This paper starts from three aspects: The theory, application and modeling framework of ABM. First, we summarize the theoretical basis of ABM and introduce some related concepts. Then we expound the application and development of ABM in both urban land systems and agricultural land systems, and further introduce the case study of a model on Grain for Green Program in Hengduan Mountainous region, China. On the basis of combing the ABM modeling protocol, we propose the land system ABM modeling framework and process from the perspective of agents. In terms of urban land use, ABM research initially focused on the study of urban expansion based on landscape, then expanded to issues like urban residential separation, planning and zoning, ecological functions, etc. In terms of agricultural land use, ABM application presents more diverse and individualized features. Research topics include farmers’ behavior, farmers’ decision-making, planting systems, agricultural policy, etc. Compared to traditional models, ABM is more complex and difficult to generalize beyond specific context since it relies on local knowledge and data. However, due to its unique bottom-up model structure, ABM has an indispensable role in exploring the driving forces of land change and also the impact of human behavior on the environment.

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    Distribution of fluoride in surface water and a health risk assessment in the upper reaches of the Yongding River
    WANG Tao, SHAO Zhijiang, YU Hui, BAH Hamidou
    Journal of Geographical Sciences    2020, 30 (6): 908-920.   doi: 10.1007/s11442-020-1761-4
    Abstract106)   HTML1)    PDF (1759KB)(8)      

    The excessive exposure to high concentrations of fluoride in drinking water can lead to a serious disease called fluorosis. The upstream region of the Yongding River is an ecological protection area for Beijing. Some studies have reported that there is a high concentration of fluoride in the groundwater in this area. However, there are few data on the distribution of fluoride in surface water and health risk assessments in this area. In this study, the fluoride concentrations were determined by using the spectrophotometric method using data from 2013 to 2017 from 9 surface water quality monitoring stations in the upper reaches of the Yongding River. The health risks of fluoride were assessed using the approach developed by the United States Environmental Protection Agency (US EPA). The results indicated that the fluoride content in the drinking water ranged from 0.30 to 1.50 mg L-1, with an average of 0.86 mg L-1. In total, 22.7% of the analyzed samples exceeded the Chinese limit of 1.0 mg L-1 for fluoride, and 5.5% of samples had less than the permissible limit of 0.5 mg L-1. Higher fluoride concentrations and fluorosis hotspots were found to be predominately located downstream of the Yanghe River close to the Guanting Reservoir, where 71.4% of samples exceeded the limit of 1.0 mg/L-1. The spatial distribution of high fluoride concentrations was found to be primarily determined by industry. The hazard quotient (HQ) index for children, teenagers and adults indicated that 19.6%, 15.6%, and 5.1% of the samples in the upper reaches of the Yongding River, respectively, posed health hazards to the associated groups. Furthermore, the HQ index more than 1 for children, teenagers and adults had values of 64.3%, 56.1%, and 19.4%, respectively, in samples from the downstream region of the Yanghe River. Therefore, there are potential risks of dental and skeletal fluorosis in the upper river reaches of the Yongding River. It is imperative to take measures to reduce the fluoride pollution in surface water and control fluorosis. Action should be taken to improve the disposal of industrial waste.

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    Exploring the spatio-temporal impacts of farmland reforestation on ecological connectivity using circuit theory: A case study in the agro-pastoral ecotone of North China
    LIU Xiaojing, LIU Dianfeng, ZHAO Hongzhuo, HE Jianhua, LIU Yaolin
    Journal of Geographical Sciences    2020, 30 (9): 1419-1435.   doi: 10.1007/s11442-020-1790-z
    Abstract97)   HTML3)    PDF (2801KB)(18)      

    Farmland reforestation can contribute substantially to ecological restoration. Previous studies have extensively examined the ecological effects of farmland reforestation, but few of them have investigated the spatiotemporal responses of broad-scale landscape connectivity to reforestation. By using a typical agro-pastoral ecotone in northern China as a case study, we addressed this issue based on an innovative integration of circuit theory approach and counterfactual analysis. The forest connectivity through multiple dispersal pathways was measured using the circuit theory approach, and its spatiotemporal changes after reforestation were evaluated by counterfactual analysis. The results showed that from 2000-2015, the reforested farmland occupied 2095 km2, and 12.5% was on steeply sloped land. Farmland reforestation caused a greater increase in ecological connectivity by adding new ecological corridors and stepping stones in scattered forest areas rather than in areas with dense forest distributions. The newly added corridors and stepping stones were fragmented, short and narrow and thus deserve powerful protection. Future reforestation to improve landscape connectivity should highlight pinch point protection and obstacle removal as well as the tradeoff between farmland loss and farmer survival. Our findings are expected to inform the optimization of the Grain for Green policy from the perspective of broad-scale biodiversity conservation.

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    Impact of cultivated land fragmentation on spatial heterogeneity of agricultural agglomeration in China
    XU Weiyi, JIN Xiaobin, LIU Jing, ZHOU Yinkang
    Journal of Geographical Sciences    2020, 30 (10): 1571-1589.   doi: 10.1007/s11442-020-1800-1
    Abstract95)   HTML32)         

    Systematically revealing the impact of cultivated land fragmentation (CLF) on the geographical agglomeration pattern of agricultural specialization (AS) has positive significance for national agricultural production management. Based on the data of the second national land survey and agricultural production, this study has explored the impact of CLF on spatial heterogeneity of agricultural agglomeration in China by comprehensively using the Theil index, ordinary least square model and geographically weighted regression. Results showed that: (1) the regional differentiation of the CLF in China is obvious, and the cultivated land fragmentation index is generally characterized by increasing pattern from northwest to southeast. (2) Spatially, the development level of AS in China has formed three high-value clusters in the Northeast China Plain, the Qinghai-Tibet Plateau, and the middle of the Middle-lower Yangtze Plain; and the low-value contiguous areas centered on the Yunnan-Guizhou Plateau and the Sichuan Basin and surrounding regions, with significant spatial differences. The contribution of grain crops, economic crops, and vegetables and melon to the level of AS was 74.63%, 9.09%, and 16.28%, respectively, and the pattern of agricultural geographical aggregation dominated by grain crops has primarily taken in shape. (3) CLF is significantly negatively correlated with AS, and every 1% increase in the degree of CLF will result in a decrease of about 0.2% in AS. However, the impact of CLF on the geographic agglomeration of different crop categories or groups varies significantly. Among them, CLF has a prominent impact on the specialization level of grain crops and vegetables and melon. Each 1% increase in the CLF will reduce the specialization level of grain crops by 0.38%, and increase the level of vegetables and melon by about 0.22%. (4) According to the landscape characteristics of cultivated land, the degree of spatial division and agglomeration of cultivated land patches have a significant impact on the formation of geographical agglomeration pattern of AS, and the intensity and direction of influence show significant regional differentiation, while the patch size has no significant impact.

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    Identification of the key factors affecting Chinese carbon intensity and their historical trends using random forest algorithm
    TANG Zhipeng, MEI Ziao, LIU Weidong, XIA Yan
    Journal of Geographical Sciences    2020, 30 (5): 743-756.   doi: 10.1007/s11442-020-1753-4
    Abstract93)   HTML3)    PDF (685KB)(387)      

    The Chinese government ratified the Paris Climate Agreement in 2016. Accordingly, China aims to reduce carbon dioxide emissions per unit of gross domestic product (carbon intensity) to 60%-65% of 2005 levels by 2030. However, since numerous factors influence carbon intensity in China, it is critical to assess their relative importance to determine the most important factors. As traditional methods are inadequate for identifying key factors from a range of factors acting in concert, machine learning was applied in this study. Specifically, random forest algorithm, which is based on decision tree theory, was employed because it is insensitive to multicollinearity, is robust to missing and unbalanced data, and provides reasonable predictive results. We identified the key factors affecting carbon intensity in China using random forest algorithm and analyzed the evolution in the key factors from 1980 to 2017. The dominant factors affecting carbon intensity in China from 1980 to 1991 included the scale and proportion of energy-intensive industry, the proportion of fossil fuel-based energy, and technological progress. The Chinese economy developed rapidly between 1992 and 2007; during this time, the effects of the proportion of service industry, price of fossil fuel, and traditional residential consumption on carbon intensity increased. Subsequently, the Chinese economy entered a period of structural adjustment after the 2008 global financial crisis; during this period, reductions in emissions and the availability of new energy types began to have effects on carbon intensity, and the importance of residential consumption increased. The results suggest that optimizing the energy and industrial structures, promoting technological advancement, increasing green consumption, and reducing emissions are keys to decreasing carbon intensity within China in the future. These approaches will help achieve the goal of reducing carbon intensity to 60%-65% of the 2005 level by 2030.

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    Coupled Human and Natural Cube: A novel framework for analyzing the multiple interactions between humans and nature
    LIU Haimeng, FANG Chuanglin, FANG Kai
    Journal of Geographical Sciences    2020, 30 (3): 355-377.   doi: 10.1007/s11442-020-1732-9
    Abstract91)   HTML13)    PDF (4623KB)(35)      

    Understanding the interactions between humans and nature in the Anthropocene is central to the quest for both human wellbeing and global sustainability. However, the time-space compression, long range interactions, and reconstruction of socio-economic structures at the global scale all pose great challenges to the traditional analytical frameworks of human-nature systems. In this paper, we extend the connotation of coupled human and natural systems (CHANS) and their four dimensions—space, time, appearance, and organization, and propose a novel framework: “Coupled Human and Natural Cube” (CHNC) to explain the coupling mechanism between humans and the natural environment. Our proposition is inspired by theories based on the human-earth areal system, telecoupling framework, planetary urbanization, and perspectives from complexity science. We systematically introduce the concept, connotation, evolution rules, and analytical dimensions of the CHNC. Notably there exist various “coupling lines” in the CHNC, connecting different systems and elements at multiple scales and forming a large, nested, interconnected, organic system. The rotation of the CHNC represents spatiotemporal nonlinear fluctuations in CHANS in different regions. As a system continually exchanges energy with the environment, a critical phase transition occurs when fluctuations reach a certain threshold, leading to emergent behavior of the system. The CHNC has four dimensions—pericoupling and telecoupling, syncoupling and lagcoupling, apparent coupling and hidden coupling, and intra-organization coupling and inter-organizational coupling. We mainly focus on the theoretical connotation, research methods, and typical cases of telecoupling, lagcoupling, hidden coupling, and inter-organizational coupling, and put forward a human-nature coupling matrix to integrate multiple dimensions. In summary, the CHNC provides a more comprehensive and systematic research paradigm for understanding the evolution and coupling mechanism of the human-nature system, which expands the analytical dimension of CHANS. The CHNC also provides a theoretical support for formulating regional, sustainable development policies for human wellbeing.

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    Using water isotopes and hydrogeochemical evidences to characterize groundwater age and recharge rate in the Zhangjiakou area, North China
    ZHANG Qinghua, LUO Zhuanxi, LU Wen, HARALD Zepp, ZHAO Yufeng, TANG Jialiang
    Journal of Geographical Sciences    2020, 30 (6): 935-948.   doi: 10.1007/s11442-020-1763-2
    Abstract91)   HTML1)    PDF (1245KB)(344)      

    Despite the increasing depletion of the groundwater at the Zhangjiakou aquifer system in the northwest of Beijing-Tianjin-Hebei region, little information is available on the hydrological process of groundwater in this region. In this study, we utilized water isotopes composition (δ18O, δD and3H) of groundwater, river and precipitation to identify the characteristics of hydrochemistry, groundwater age and recharge rates in different watersheds of the Zhangjiakou area. Results showed that the river water and groundwater could be characterized as HCO3-Mg·Na, HCO3·Cl-Na and HCO3-Mg·Na, HCO3·Cl-Na, HCO3·Cl-Na·Mg types, respectively. The δD and δ18O values in precipitation were linearly correlated, which is similar to the Global Meteorological Water Line (GMWL). Furthermore, the decreasing values of the δD and δ18O from precipitation to surface water and groundwater indicate that groundwater is mainly recharged by atmospheric precipitation. In addition, the variation of3H concentration with depth suggests that groundwater shallower than around 100 m is generally modern water. In contrast, groundwater deeper around 100 m is a mixture of modern and old waters, which has longer residence times. Groundwater showed a relatively low tritium concentration in the confined aquifers, indicating the groundwater recharged might be relatively old groundwater of over 60 years. The flow velocity of the groundwater in the study area varied from 1.10 to 2.26 m/a, and the recharge rates ranged from 0.034 to 0.203 m/a. The obtained findings provide important insights into understanding the groundwater recharge sources and hydrochemistry in the Zhangjiakou area, in turn developing a sustainable groundwater management plan.

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    A review of mass flux monitoring and estimation methods for biogeochemical interface processes in watersheds
    LU Yao, GAO Yang, YANG Tiantian
    Journal of Geographical Sciences    2020, 30 (6): 881-907.   doi: 10.1007/s11442-020-1760-5
    Abstract89)   HTML12)    PDF (1511KB)(24)      

    The magnitude of mass flux is closely associated with biogeochemical watershed processes, which can generate a considerable amount of pertinent information. Moreover, both the accuracy and precision of mass flux estimation results directly affects the perception of the ecological environmental status, which in turn affects both the formulation and implementation of river basin management planning. In practical applications, the true value of flux is unknown and can only be estimated. Flux results obtained using different monitoring and estimation methods also differ significantly. However, in existing studies on mass flux associated with biogeochemical watershed interfaces, the application of monitoring and estimation methods lacks uniform criteria or references. Accordingly, this study summarizes and deconstructs results from recent studies on biogeochemical watershed interface processes and compares the advantages, disadvantages and applicability of the monitoring and estimation methods used by these studies. This particular study is intended to be used as a reference for the selection of flux calculation methods.

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    Differential changes in precipitation and runoff discharge during 1958-2017 in the headwater region of Yellow River of China
    HOU Bingfei, JIANG Chao, SUN Osbert Jianxin
    Journal of Geographical Sciences    2020, 30 (9): 1401-1418.   doi: 10.1007/s11442-020-1789-5
    Abstract87)   HTML1)    PDF (1635KB)(3)      

    Maintenance of steady streamflow is a critical attribute of the continental river systems for safeguarding downstream ecosystems and agricultural production. Global climate change imposes a potential risk to water supply from the headwater by changing the magnitude and frequency of precipitation and evapotranspiration in the region. To determine if and to what extent the recent climate changes affected streamflow in major river systems, we examined the pattern of temporal variations in precipitation, temperature, evapotranspiration and changes in runoff discharge during 1958-2017 in the headwater region of the Yellow River in northeastern Tibetan Plateau. We identified 1989 as the turning point for a statistically significant 14% reduction in streamflow discharge (P < 0.05) for the period 1989-2017 compared with 1958-1988, approximately coinciding with changes in the monthly distribution but not the interannual variations of precipitation, and detected a mismatch between precipitation and runoff after 2000. Both annual precipitation and runoff discharge displayed four- and eight-year cyclic patterns of changes for the period 1958-1988, and a six-year cyclic pattern of changes for the period 1989-2017, with two intensified two-year cyclic patterns in the changes of precipitation and a three-year cyclic pattern in the change of runoff further detected for the later period. Our results indicate that the temporal changes in runoff are not strictly consistent with the temporal variations of precipitation in the headwater region of Yellow River during the period 1958-2017. In particular, a full recovery in annual precipitation was not reflected in a full recovery in runoff toward the end of the study period. While a review of literature yielded no apparent evidence of raised evapotranspiration in the region due to recent warming, we draw attention to increased local retention of rainwater as a possible explanation of differential changes in precipitation and runoff.

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    Attribution analysis for water yield service based on the geographical detector method: A case study of the Hengduan Mountain region
    DAI Erfu, WANG Yahui
    Journal of Geographical Sciences    2020, 30 (6): 1005-1020.   doi: 10.1007/s11442-020-1767-y
    Abstract86)   HTML1)    PDF (2338KB)(11)      

    Ecosystem services, which include water yield services, have been incorporated into decision processes of regional land use planning and sustainable development. Spatial pattern characteristics and identification of factors that influence water yield are the basis for decision making. However, there are limited studies on the driving mechanisms that affect the spatial heterogeneity of ecosystem services. In this study, we used the Hengduan Mountain region in southwest China, with obvious spatial heterogeneity, as the research site. The water yield module in the InVEST software was used to simulate the spatial distribution of water yield. Also, quantitative attribution analysis was conducted for various geomorphological and climatic zones in the Hengduan Mountain region by using the geographical detector method. Influencing factors, such as climate, topography, soil, vegetation type, and land use type and pattern, were taken into consideration for this analysis. Four key findings were obtained. First, water yield spatial heterogeneity is influenced most by climate-related factors, where precipitation and evapotranspiration are the dominant factors. Second, the relative importance of each impact factor to the water yield heterogeneity differs significantly by geomorphological and climatic zones. In flat areas, the influence of evapotranspiration is higher than that of precipitation. As relief increases, the importance of precipitation increases and eventually, it becomes the most influential factor. Evapotranspiration is the most influential factor in a plateau climate zone, while in the mid-subtropical zone, precipitation is the main controlling factor. Third, land use type is also an important driving force in flat areas. Thus, more attention should be paid to urbanization and land use planning, which involves land use changes, to mitigate the impact on water yield spatial pattern. The fourth finding was that a risk detector showed that Primarosol and Anthropogenic soil areas, shrub areas, and areas with slope <5° and 25°-35° should be recognized as water yield important zones, while the corresponding elevation values are different among different geomorphological and climatic zones. Therefore, the spatial heterogeneity and influencing factors in different zones should be fully considered while planning the maintenance and protection of water yield services in the Hengduan Mountain region.

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    Holocene hydro-environmental evolution and its impacts on human occupation in Jianghan-Dongting Basin, middle reaches of the Yangtze River, China
    ZHAO Chengshuangping, MO Duowen
    Journal of Geographical Sciences    2020, 30 (3): 423-438.   doi: 10.1007/s11442-020-1735-6
    Abstract82)   HTML1)    PDF (12649KB)(13)      

    Based on the comprehensive analyses of 18 core profiles’ sedimentary sequences and lithological characteristics in Jianghan-Dongting Basin of the middle reaches of the Yangtze River and the spatial-temporal distribution of archeological sites in this area, we reconstructed the Holocene hydro-environmental evolution, and its relationship with human occupation. The comparison reveals: 11.5-5.5 ka BP, the water level of rivers and lakes in the middle Yangtze River appeared a rising trend, concurrently, under the development of Neolithic culture and rice agricultural activities, human occupation extended from piedmont plain to inner basin plain in the study area. The water level fell in 5.5-4.0 ka BP, meanwhile, the number of human settlements of Qujialing-Shijiahe culture rapidly increased, especially in the inner basin plain. The water level rose again around 4.0 ka BP, floods spread massively in this period, which led to the decline of Shijiahe culture. The main causes for hydro-environmental evolution in the study area are the fluctuation of sea level and the aggradation of fluvio-lacustrine sediments.

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    Effects of land use and cultivation time on soil organic and inorganic carbon storage in deep soils
    YU Xia, ZHOU Weijian, WANG Yunqiang, CHENG Peng, HOU Yaoyao, XIONG Xiaohu, DU Hua, YANG Ling, WANG Ya
    Journal of Geographical Sciences    2020, 30 (6): 921-934.   doi: 10.1007/s11442-020-1762-3
    Abstract78)   HTML1)    PDF (2472KB)(269)      

    The vertical distribution and exchange mechanisms of soil organic and inorganic carbon (SOC, SIC) play an important role in assessing carbon (C) cycling and budgets. However, the impact of land use through time for deep soil C (below 100 cm) is not well known. To investigate deep C storage under different land uses and evaluate how it changes with time, we collected soil samples to a depth of 500 cm in a soil profile in the Gutun watershed on the Chinese Loess Plateau (CLP); and determined SOC, SIC, and bulk density. The magnitude of SOC stocks in the 0-500 cm depth range fell into the following ranking: shrubland (17.2 kg m-2) > grassland (16.3 kg m-2) > forestland (15.2 kg m-2) > cropland (14.1 kg m-2) > gully land (6.4 kg m-2). The ranking for SIC stocks were: grassland (104.1 kg m-2) > forestland (96.2 kg m-2) > shrubland (90.6 kg m-2) > cropland (82.4 kg m-2) > gully land (50.3 kg m-2). Respective SOC and SIC stocks were at least 1.6- and 2.1-fold higher within the 100-500 cm depth range, as compared to the 0-100 cm depth range. Overall SOC and SIC stocks decreased significantly from the 5th to the 15th year of cultivation in croplands, and generally increased up to the 70th year. Both SOC and SIC stocks showed a turning point at 15 years cultivation, which should be considered when evaluating soil C sequestration. Estimates of C stocks greatly depends on soil sampling depth, and understanding the influences of land use and time will improve soil productivity and conservation in regions with deep soils.

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