Achieving sustainable development in an increasingly interconnected globalized world requires cross-system thinking and more integrated regional policy. First, it requires disciplines devoted to sustainable development research to improve their insights into trans-regional resource and environmental issues. Accordingly, it is necessary to promote the adaptive innovation and transformation of the traditional research framework of geography. Telecoupling, as a theoretical framework focusing on socioeconomic and environmental interactions among coupled human and natural systems over distances, has great potential and advantages to facilitate the process of theoretical innovation. In order to narrow the gap between Chinese and international research in the field of telecoupling, we introduce the telecoupling framework and its application progress from theoretical construction, empirical evidence, key research areas, and research methods based on literature review, document analysis, and our own understanding of telecoupling, and further give some suggests. The review shows that there is a large amount of empirical evidence of telecoupling in the dimensions of teleconnection, globalization, and urbanization due to the continuous growth of long-distance human activities and their interaction with large-scale natural processes. Currently, the application of the telecoupling framework in academia mainly focuses on three aspects: ecosystem services, the socioeconomic and environmental impacts of telecoupling, and land change science. Due to the progress in operationalizing the theories, current telecoupling research has been well supported methodologically. We further argue that geographical research based on the telecoupling framework should make breakthroughs in the theoretical innovation of Human-Earth relationship network system, telecoupling mechanism, and telecoupling regulatory tool sets, so that scientific research can keep up with the latest trends and solve the emerging real world problems.
Geopolitical risk is one of the five categories of risk identified in the World Economic Forum's Global Risks Report, with significant effects on the global and regional peace, stability, and development. How to identify, measure, forecast, and manage the impact that geopolitical risks on human well-being are taken into consideration by researchers worldwide. Global scientific researchers have not yet reached a consensus on the definition of geopolitical risks. Geopolitical risk research has made notable progress in the fields of 1) analyzing the causal factors of geopolitical risks; 2) identifying the impact of geopolitical risks; and 3) measuring and mapping geopolitical risks. Considering the fact that challenges come from the spatiotemporal differences and variability of geopolitical risk factors, the complexity of the various risk causing factors on interaction and response mechanisms, and the unpredictability and uncertainty of geopolitical risks, geopolitical risk research has made further progress on the following frontier issues: 1) identification of geopolitical risk causing factors; 2) occurrence mechanism of geopolitical risks; and 3) monitoring and simulation of geopolitical risks. Future directions of geopolitical risk research in China include: 1) research on national geo-security with spatial differentiation, especially forthesurrounding areas of China; 2) quantitative reconstruction and numerical simulation of the geopolitical risks across multiple scales and multiple geo-factors; 3) new computation ways supporting the interaction of other scientific disciplines and the use of big data, and new platform integrating early warning of geopolitical risks; 4) focusing on scientific issues and promoting the ability of theoretical and practical research output in dealing with geopolitical issues.
China is in a critical period of economic transformation and social development, which brings great pressure and challenges to land use. Therefore, imbalanced land-use structure and conflicting land utilization become more common, which result in more attention to land-use conflicts and thus increasingly more related studies has appeared, but there is a lack of systematic review and compilation of existing research. This study examined the research related to land-use conflicts in China through literature analysis and comparative analysis, and identified the research trends. First, this article points out that land-use conflict refers to the phenomenon of spatial competition and conflicting interests between people and land caused by the way and structure of land use by stakeholders in the process of land use, which was defined by the comparison and identification among relevant concepts related to land-use conflicts in the existing literature. Second, the Chinese land-use conflict research results were summarized and elaborated from six aspects, including the theoretical basis of land-use conflicts, the stakeholders in land-use conflicts, the identification and intensity diagnosis of land-use conflicts, the forms and classification of land-use conflicts, the evolution of land-use conflicts and its driving mechanisms, and the reconciliation program of land-use conflicts. Finally, through reviewing and comparing Chinese and international research results, this article puts forward the future direction of China's land-use conflict research: 1) Complement and improvement of land-use conflicts theoretical system under the background of economic and social transformation. 2) Content expansion and paradigm innovation of land-use conflict research considering the global scale. 3) Spatial justice and efficiency of land-use conflict resolution in the context of rural revitalization strategy. 4) Quantitative and precision management of land-use conflicts with the support of participatory GIS. 5) Coordination and trade-off of land-use conflict resolution under the integration of national spatial planning systems. 6) Comprehensive analysis and results application of land-use conflicts from the perspective of multidisciplinary integration.
From the spatial perspective, an urban agglomeration can be understood as the concentration of population and economic activities within a large urban region. In this urban region, the original rural areas were densely involved in industrialization and economic development. On the basis of a comprehensive review of classical theories, this article proposes to understand urban agglomeration from the unique characteristics of spatial patterns, namely, dispersed regional concentration. We believe that the dispersed regional concentration is the result of spatial choices of economic globalization and information technology revolution, and also the product of the unique policies and institutional background of China. As a unique reflection of global manufacturing platform and coordinated control center in space, this fundamental attribute makes urban agglomeration different from traditional regions and not ubiquitous in space. Its dispersive development characteristics represents the most serious resource and environmental constraints, which deserve special attention. The planning strategy based on these decentralized regional units may be easier to implement and achieve results than the current overall urban agglomeration strategy. At the same time, with the implementation of domestic consumption demand strategy and the Belt and Road initiative, the Chinese and international backgrounds of urban agglomeration development are undergoing important transformations. The spatial pattern of dispersed regional concentration does not necessarily apply to all regions of China. This fact is of great significance and must be carefully considered in future regional planning and management.
Under the background of global environmental change and urbanization, various risks and uncertainties have posed an important obstacle on urban security and urban sustainable development. As a potential new approach of urban risk management, urban resilience can improve the ability to resist, dissolve, and adapt when facing risks and uncertainties, and expound the adaptive scheme of risks in the process of rapid urbanization. Urban resilience has been a new topic in geography and related disciplines. Based on the origin and concept of urban resilience research, from the perspective of the impact of various factors (human, environmental, disaster) on urban resilience, this study constructed a theoretical framework of urban resilience, including evaluation and scenario simulation, and discussed the status of urban resilience research, pointing out that there are still many weak links in the theoretical framework, mechanism, practical application, and difference analysis of urban resilience research. Finally, the key directions of urban resilience research were also discussed. The theoretical framework should be used as a guide to promote multi-objective, multi-level, and multi-perspective systematic evaluation research. With the analysis of mechanism as support, studies should aim to achieve a new breakthrough in process simulation of urban resilience and decision making and early warning. Oriented by empirical research, studies should continue to strengthen the application model of multidisciplinary integration and exploration of urban resilience. Considering regional differences, further work should try to achieve a change in urban planning from the unified "one policy for multi-city" approach to the flexible "one policy for one city" approach.
As a new organizational form and research paradigm of urban spatial system, city network has been widely concerned in recent years. However, most of the studies on city networks were based on a positive perspective, while the negative effects, security, and sustainable development of city networks were rarely addressed. By reviewing the literature of city network and regional resilience, this article tentatively proposed a concept and an analytical framework of city network resilience based on evolutionary resilience theory to explore the "negative problems" of city networks. In brief, city network resilience could be comprehended as the ability of city network systems to prevent, resist, respond to, and adapt to the impact of external acute shocks and chronic pressures and recover from them or switch into another development path by means of the cooperation and complementarity of social, economic, organizational, and engineering fields among cities. Based on this concept, combining evolutionary resilience and adaptive cycle theory, a city network was regarded as a complex adaptive system with dynamic changes. Based on the social network, economic network, organizational network, and infrastructure network, considering both adaptation and adaptability, a framework of urban network resilience analysis from the perspective of resilience characteristics and resilience processes was proposed. Furthermore, the analysis and optimization methods of urban network resilience were prospected, and some core issues involved were discussed. The research aimed to provide a scientific basis for regional planning, regional policy formulation, and regional organization establishment with the goal of achieving safe development, and provide valuable references for each city node to identify its role in a region and participate in regional governance.
The traditional extensive urban land use will not meet the requirements of new urbanization. As a result, controlling urban sprawl and land use optimization have become one of the key tasks of land resources management. The purpose of this study is to provide new perspectives and identify research areas for urban growth boundary study through the review and analysis of existing theoretical models, methods, and effectiveness evaluation cases. The research methods we employed are literature review and induction and deduction. The results indicate that the theoretical basis of urban growth analysis came from monocentric city model. Most studies in China mainly focused on the impact of economic factors, industrial structure, and accessibility on urban growth while public policies and services, externality, and stakeholder power struggles are also thought to have effects on urban growth. Urban growth rigid boundary design is mainly based on suitability and carrying capacity assessments, and elastic boundary is usually modeled by using cellular automata. The effectiveness of urban growth boundary on controlling urban sprawl is different in different cities in developed countries. There are few case studies to evaluate the effectiveness of urban growth boundary in China. We should adopt diversified theories to study the mechanism of urban growth. The effects of multilevel drivers on urban growth should be considered in future research. Most importantly, stakeholder power struggles should be taken into consideration in future elastic boundary modeling. In order to make urban growth boundary policies sustainable and balance regional development, legal and management systems of urban growth boundary should be designed in the future.
The study on identification and optimization of production-living-ecological spaces is to optimize the layout of future space based on identifying the structure, pattern, and problems of current spaces, which is a more comprehensive land spatial zoning approach and an urgent practical problem in national spatial planning, as well as a frontier of academic research. In this study, literature review methods, comparative analysis, and induction were performed to systematically summarize the current research situation of the concept and connotation, identification, and optimization of production-living-ecological spaces. At present, the research on the identification and optimization of production-living-ecological spaces has made a major breakthrough. However, the internal mechanism and concept of the formation of production-living-ecological spaces were insufficiently examined. The quantitative identification method and technical system of production-living-ecological spaces need to be improved. The dynamic change and driving mechanism, spatial conflict diagnosis, and problem analysis of production-living-ecological spaces were weakly researched. Optimization theory and technology system of production-living-ecological spaces were still in the initial stage. We propose the following future directions: Forming the concept of quality and quantity in future research; Attaching importance to lessons-learned from the existing research results of international spatial planning; With formation mechanism and concept definition, quantitative identification, mechanism of change examination, conflict diagnosis, and problem analysis and optimization control and simulation of production-living-ecological spaces as the main research lines, constructing the theory and technical system of identification and optimization of production-living-ecological spaces. Meanwhile, more attention should be paid to mountainous areas with horizontal and vertical features.
River is one of the most significant factors in driving the formation and evolution of landforms as well as one of the most important freshwater resources on the Earth. River characteristics, including water extent, water level/water depth, river discharge, water quality, and ice coverage, are vital to the dynamic monitoring of water resources and protection of eco-hydrological systems. Traditional methods of acquiring river characteristics are to use in situ data that were collected on hydrological gauges, which costs large amount of financial and material resources. It is urgent to develop a way of supplementing in situ data of rivers quickly and accurately for the increasing demand of river information. With the ability of omnidirectional and multi-temporal Earth observation, remote sensing has greatly improved the efficiency of acquiring river characteristics. It has been applied broadly in multi-scale river monitoring and hydrological simulation in ungauged basins. Therefore, it is necessary to summarize recent progresses in the field of remote sensing based river characteristics inversion, in order to further promote the application of remote sensing data and methods in this field. This article, therefore, focusing on remote sensing of river characteristics, summarizes recent progresses systematically on the extraction of water extent, inversion of water level/water depth, estimation of river discharge, and monitoring of water quality and ice coverage. Advantages and disadvantages of applying optical and microwave remote sensors for obtaining water extent and water level/depth are discussed in detail. The advanced data, specific methods, and related emerging technologies in this field are discussed and the following conclusions are made: 1) Newly available remotely sensed data have been making creative breakthroughs in spatial resolution, temporal resolution, and spectral resolution, which dramatically enrich data sources for river studies. 2) Most optical images still face the challenge of mixed pixels, while the application of SAR images is suffering from difficulties in developing complex processing algorithms. Meanwhile, accurate extractions of narrow and non-open waters need further research in the future. 3) The development of big data and cloud computing technologies provide excellent means for monitoring river characteristics at large spatial scales and long temporal scales, with both high spatial and high temporal resolutions.
Designing hyetographs is the basis of deducing design flood for small and medium-sized watersheds lacking flow data. It has a significant impact on construction standards of water conservancy facilities and municipal engineering design. Therefore, a large number of studies on design hyetograph has been carried out in China and internationally. In recent years, due to the impact of climate and environmental changes, great floods occur frequently. Mountain floods and waterlogging in urban areas pose a threat to the property and personal safety of mountain people and urban residents, and have caused many disasters. Therefore, higher requirements are put forward for the design of hyetographs. This article systematically summarized the principles and methods for selecting typical hyetographs and the classification of hyetographs, and reviewed the methods of deducing hyetographs in China and abroad, including the Chicago Hyetographs, the Huff Hyetographs, the Triangle Rainfall Hyetographs, and the Pilgrim & Cordery (P&C) Hyetographs—our short-duration design hyetographs in total, as well as the long-duration Soil Conservation Service (SCS) Hyetographs and the same-frequency method. Finally, the problems in designing hyetographs in small and medium-sized watersheds and the prospects for future research are put forward.
After the global financial crisis in 2008, many countries around the world have made great efforts to create a sustainable future, and green development has been seen as the most important pathway to sustainability. As a new research perspective in the area of sustainable development, green development has drawn great attention from academic researchers globally in recent years and has become interdisciplinary-oriented. As an applied basic research field for exploring the structural change of resources and environment and regional sustainable development, geography plays an essential role in the research of green development. Based on an intensive literature review, this article summarized the connotation and analytical framework of green development at first, then systematically outlined the progress of green development research from the perspective of geography and extracted seven themes, that is, the influencing factors of green development, assessment methods, spatial and temporal characteristics of green development, green development and industrial transformation, green transformation of resource-based cities, the effect of green development, and green development institutions and recommendations. Comments were made on the existing studies and shortcomings of existing research were analyzed. Finally, future research emphases were discussed, with the aim to provide references for studying green development from the perspective of geography in China.
The studies on the space of flow play an important role in understanding the structure and change of urban networks. The rapid development of big data provides new opportunities and challenges for the studies on the space of flow in recent years. This article systematically reviewed the research progress on the space of flow based on big data. First, we retrospect the background and history of the studies on the space of flow, then summarized the themes, the types of big data, the methods used for the studies and the major findings, as well as discussed the research challenges. We found an exponential growth of studies on the space of flow using big data after 2011. The annual number of published papers increased from 11 to 106 during 2011-2018. Big data deepen the research on the space of flow by providing new data sources, inspiring new analytical methods, and new research perspectives. Four types of big data—mobile phone, social media, smart card, and taxi trajectory data are commonly used in the studies on the space of flow, which can provide information on spatiotemporal flows (such as population flow, material flow, and information flow) directly. Research methods have also evolved from distance-based gravity models to network analysis. In the future, the research on the space of flow using big data can be further improved by validating the effectiveness and representativeness of the big data, the integration of big data and traditional data, and the information mining from big data using new methods such as deep learning and cloud computing.
With global climate change and rapid urbanization, extreme weather events have become much more frequent. As one of the most typical extreme weather events caused by climate change, heat wave has been enhancing the heat-related health risks, and continuously attracting widespread attention from meteorologists, medical professionals and geographers. As a bridging actor integrating meteorological and medical fields, geography provides spatial indicators for heat wave vulnerability assessment, ideas and methods for mapping, spatial solutions for practical work such as planning and early warning. This article systematically reviews the progress of spatial assessment of heat wave vulnerability based on the perspective of geography. The contents include the definition of heat wave, spatial indicators and mapping methods. The literature reviews indicate that heat wave vulnerability assessment has gradually deepened from single perspective to the interdisciplinary study of meteorology, medicine, geography and other disciplines. In the future, more detailed exploration will be carried out, such as the construction of spatial indicators to integrate the advantages and research demands of various disciplines; the exploration about small-scale community to regional large-scale links and cross-regional research expression by mapping. Spatial approaches require differentiated research among different groups, which provide a scientific basis for climate change adaptation of cities.
Spatial configuration has a significant impact on the efficient and balanced development of cities and regions. Following the rapid expansion of urban areas and the development of transportation and communication technologies, polycentricity has become the dominant trend of spatial restructuring in many cities and regions. Meanwhile, it has been adopted widely as an important tool of spatial configuration in urban and regional planning. However, the concept of "polycentricity", despite its wide usage in the literature, remains to be confusing and needs to be clarified. Moreover, there is no consensus on the prevalence and advantages of the polycentric form of city and regional spatial structure compared with those of the monocentric counterpart. This article reviewed the research related to polycentricity in Chinese and international literature to get a systematic comprehension of this concept. First, it analyzed the connotation of intra-city and inter-city polycentricity, morphological and functional polycentricity based on the definition of research scale and importance of centers. Second, this article reviewed the evolution mechanism of polycentric city and urban region from the perspectives of the generation of new centers and the integration of existing centers. Third, it summarized the various tools of identifying and measuring polycentricity, the development trend and performance of city and regional spatial structure. Finally, the future research prospects are proposed: 1) Defining polycentricity clearly and measuring it appropriately with some new data and tools to make the results more accurate and comparable. 2) Comparing the variation of city and regional spatial structures and analyzing the causes from the perspectives of agent's decisions and the comprehensive effect of the spatial distribution of various economic factors. 3) Evaluating the performance of polycentricity comprehensively, which means taking the environment and socioeconomic background of cities and regions into consideration when exploring the advantages and disadvantages of polycentricity in multiple perspectives.
Neuroscience is the science of the 21st century. The theoretical research results of neuroscience are affecting daily life, environment, space, context, and place profoundly. It provides a new way of thinking and method to explain human's mind and behavior. In the context of post-modernism, the understanding of self-consciousness in human geography has become fragmented. Non-presentation theory and embodied cognitive geography claim that in most of the time, people are "unconscious". Subject self-consciousness is irrational, which takes place in the "outflows" daily life world. It emphasizes the showing, performance, and practice of the body. The meaning of the real world should be obtained through embodied cognition and behavior. They found evidence from neuroscience that led to a "neural turn" in geography. The "neural turn" devotes to linking human's mind and behavioral traits to biological evidence. It is different from inter-disciplinary debates that are breaking down the disciplinary boundaries between social culture and natural sciences. The laboratory methods cannot reflect the real world, and the social science methods are difficult to get rid of subjective factors. The "neural turn" can provide a research perspective of combining the-first-person and the-third-person for human geography. This article reviewed the recent studies on the "neural turn" in Western human geography. "Neural turn" research mainly concentrated in three aspects: space perception, embodied affect, and behavior practice. It has involved economic, political, social, cultural, public policy, tourism, and education topics. The application of neuroscience in human geography can also be applied to multiple scales of space such as country, city, community, and body. Neuroscience perspective as a new path is used in urban planning, environmental design, tourism development, and public policy, among others. At the same time, the technical tools of neuroscience have become new data collection methods in human geography. Neural technology can capture imperceptible physiological changes in the human body in order to detect neural activity caused by mind and behavior in a particular environment and context. The collection of physiological data can surmount the representation of text and symbols to discover non-representational results. Brain images and eye tracking technologies have been applied in geography, presenting predictable visions for the future. At present, Chinese human geography pays little attention to neuroscience. This article is hoped to provide some reference and enlightenment for the study of Chinese human geography. The dialogue between neuroscience and human geography is still in its infancy and needs more empirical research. In this process, human geography can carry out more cooperative research to produce more knowledge spillover. At the same time, these studies need to explore the topic of Chinese localization in order to better realize the people-oriented approach in the research and application of Chinese human geography.
Rural living space is the microcosm of rural development, which reflects the human-environment relationship in rural areas. With the implementation of the Urban-Rural Integration Strategy and the Rural Revitalization Strategy, coupled with the development of the new-type urbanization and globalization, rural space, including rural living space, has been restructured as a whole, and the countryside has entered a new period of development. In this process, how rural living space map and influence rural development is a topic worthy of discussion from multiple perspectives. Based on the review of literature, this article holds that the rural living space is the space of the daily life behavior of rural residents, a multi-level territorial complex of rural residents' living, leisure, socializing, consumption, and public service activities, and an important part of rural social space. The study of rural living space in Chinese academia started in the 1920s. According to the characteristics of different stages of economic and social development of China, this study divided the research of rural living space into four periods: the exploration period before the founding of the People's Republic of China; the stagnation period before the Reform and Opening-up; the revival period after the Reform and Opening-up; and the rapid development period since the 21st century. However, compared with international rural living space research and Chinese urban living space research, the study of rural life in China tends to be empirical, lacking comprehensive deep examination and theoretical model construction. In the new era of development, the study of rural living space in China should construct a complete research framework and carry out multi-level and all dimensional exploration on basic theories, research subjects, and diverse research perspectives.
The long-term supply-demand imbalance of rural land use functions (RLUFs) is one of the main reasons for rural issues in China. Based on the multifunctionality theory, this study explained the mutual relationship between rural land consolidation (RLC) and rural vitalization with a focus on supply-demand and element-structure-function relationships, and then discussed how to realize the supply-demand balance of RLUFs through RLC so as to promote sustainable rural development. The results show that: 1) Comprehensive rural land consolidation is a multifunctional land use method and an important means to solve rural issues for promoting rural vitalization. In essence, it is the transition from productivism that focuses on economic benefits to non-productivism that takes social, economic, and environmental benefits as a whole. 2) RLUFs include production, living, ecological, and cultural functions, corresponding to the economic, social, enviromental, and cultural demands of rural vitalization. The production functions are divided into agricultural, commercial, and industrial functions, and living functions include residential, employment, and public service functions. 3) Along the path of integrating land use elements, restructuring land use structures, and optimizing land use functions, RLC promotes the supply-demand balance of RLUFs from the supply side according to local conditions. 4) In future research, the mechanisms and modes of RLC impact on rural vitalization at different spatial scales, as well as quantitative analysis of the functional supply of land use and the functional demand of rural vitalization under the influence of RLC should be given more attention, thus laying a scientific foundation for the formulation and implementation of land use and rural vitalization planning.
Land sparing and land sharing are two alternative land-use strategies, which was framed by Green in 2005. The land-sparing versus land-sharing framework was initially designed to explore trade-offs between food production and biodiversity conservation by means of the density-yield curve. A debate on whether the land-sparing strategy or the land-sharing strategy is optimal has been on-going in the last 10 years and it has enriched relevant theories. Considering that there are many land-sparing practices but limited relevant research to provide guidance for land management in China, in this article we introduced the land-sparing versus land-sharing framework as a new perspective. We reviewed 317 articles in the Web of Science database and conducted bibliometric analysis for a better understanding of the context, methodology, and principles of the framework. The current status and historical trend referring to major topics and research subjects were analyzed. We also summarized decision-making options in previous studies and further advanced the framework from two aspects, focusing on land multi-functionality and the parallel between agriculture and urban systems. We found that land-sparing strategy was more prominent comparing with land-sharing strategy in studies and practices around the world in spite of the pros and cons of each. The advanced framework in this study extended the research object from agriculture to urban, and integrated the diversity of ecosystem services. This study may provide some guidance for the sustainable development of the social-ecological system and enrich the theoretical basis of the land-sparing versus land-sharing framework.
China has large mountain areas with low level of economic and social development. Promoting the sustainable development of mountain areas is the key to the process of modernization in China. As the core spatial unit of the regional system of human-land relationship, rural settlements in mountainous areas are the research focus and hotspot of rural geography in China. Based on the method of literature backtracking and review, this article systematically analyzed the general situation of mountain development and the influencing factors, characteristics of change, and driving mechanisms of rural settlements spatial distribution, and clarified the conceptual connotation and strategies and methods of rural settlements spatial reconstruction. Also, the main models and optimization strategies of spatial reconstruction of rural settlements in mountainous areas of China were summarized. This study considered that the spatial reconstruction of rural settlements has many typical characteristics, such as multiple subjects, multiple objectives, and diverse models, which is a dynamic and complex spatial optimization and reorganization process. In the new era of development in China, research on the reconstruction of rural settlements in mountainous areas should focus on the following five aspects: 1) The mechanism and model of rural settlements spatial reconstruction under the background of rural revitalization in mountainous areas. 2) The mechanism of impact of land use transformation on the spatial reconstruction of rural settlements in mountainous areas. 3) The impact of rural housing land system reform on the spatial reconstruction of rural settlements in mountainous areas. 4) The interactive relationship between the development of emerging industries and the spatial reconstruction of rural settlements in mountainous areas. 5) The innovation of research methods on spatial reconstruction of rural settlements in mountainous areas in the era of big data. Through the empirical analysis of the background, economic and social driving factors, mechanism, and research methods of spatial reconstruction of rural settlementsin mountainous areas, this study enriches and improves the theory of spatial reconstruction of rural settlements in mountainous areas, with a view to promoting sustainable development in mountainous areas and promoting the process of modernization.
Under the "economic space" perspective, theories and empirical studies regarding urban centers system have developed in isolation from each other. This study aimed at filling this gap with a synthesized theoretical framework. Based on a general survey of theoretical models, we argued that the formation and development of urban centers system are mainly determined by two mechanisms—spatial competition and spatial connection, generating the spatial organization of local and non-local services respectively. Then we characterized the urban centers as a "semi-lattice" system that any center in a tree-structure of local service centers could be linked to higher-level centers or even global cities by non-local functions such as those derived from the space of flow. After an in-depth discussion of this framework, we proposed several research implications regarding empirical studies. We argued that empirical identification of urban centers should be consistent with theoretical concepts; reflection from empirical studies should be further linked to the refinement of the framework; and the potential of planning intervention on centers and their spatial effects is the premise of spatial policies.