Based on the Tencent migration data in 2018, the Chinese residents' intercity travel networks were constructed respectively from different time periods (annual, daily, special holidays, and the Spring Festival travel period), different travel modes (aviation, railway, and highway) and different urban agglomerations (inside and outside). Using the social network analysis method, the spatial structure characteristics of residents' intercity travel networks were explored and depicted from the perspective of "point-line-network", and the internal and external travel patterns of major urban agglomerations were summarized to reveal residents' intercity travel laws systematically and comprehensively. The results showed that: the residents' intercity travel network in 2018 presents a spatial pattern of "dense in the east and sparse in the west", forming a top-level cross-regional "diamond" network structure with high central cities such as Beijing, Shanghai, Guangzhou-Shenzhen and Chengdu-Chongqing as the vertexes. Residents' intercity travel in the Spring Festival travel period is quite different from that in other holidays. The weighted gravity center of the residents' intercity travel is more inclined to the southwest during the Spring Festival travel period. The daily average travel scale of the Spring Festival is higher than that of other periods. There are significant differences in residents' intercity travel population scale, travel range and travel transportation network under different travel modes. The aviation intercity travel, railway intercity travel and highway intercity travel are responsible for the population gathering and dispersion of intercity travel at national level, regional level and local level, respectively. The internal and external residents' intercity travel networks of urban agglomerations respectively show a spatial pattern of "core-hinterland-periphery" and "region crossing-neighboring-locality", with obvious significant hierarchy. Affected by administrative barriers, intercity travel within an urban agglomeration is more to the capital city as the origin or destination, showing a multi-center dual-core travel pattern, while the external intercity travel of the urban agglomeration is mostly single-center single-core travel pattern.

Urban boundaries are the spatial basis for the cognition of urban evolution and urban planning decision-making. In China, "city" usually refers to a legally defined administrative unit, whose spatial boundary does not coincide with that of physical entity consisting of a continuous artificial impervious surface. However, few studies quantitatively analyze the temporal and spatial evolution of urban physical areas over long time series, especially lacking a systematic understanding of the spatial differences in urban land expansion from the views of physical and administrative areas. Based on the multi-source remote sensing products with a spatial resolution of 30 meters, we identified the physical urban boundary from 1988 to 2018 and analyzed the land expansion process of the physical area. Further, we identified the cognitive differences and spatial patterns of urban land expansion from the above two views and found the following conclusions: (1) In the past 30 years, the number of urban physcial areas in China with an area of more than five square kilometers has increased by 378%, and the most significant growth is in East and Central China. Among the physical areas, 88% of them belong to the type of "independent growth" widely distributed but most of them are smaller than 50 km², while the other 12% belongs to the type of "spatial aggregation", mainly distributed in developed areas and the area is generally large. (2) Compared to administrative units, the rank-size distribution of urban area is more complying with the power-law model. Its Zipf's exponent has gradually increased to 1 in the past 30 years, indicating development of the urban system has become more and more balanced. Compared to physical areas, administrative area have larger land expansion area in plain areas and lower land expansion intensity in coastal areas. (3) The 1327 county-level administrative units that cannot topologically match the urban physical area are mostly distributed in densely populated or developed plain areas. Combining two views, two types of spatial expansion have been further identified, namely "inter-districts co-urbanization" and "intra-district clustering". The former occurs in provincial capital area, while the latter is mainly distributed in the developed areas of the North China Plain. Both reflect the spatial reconstruction of urbanization. This research is helpful to deepen the understanding of the spatiotemporal process of China's land urbanization and provide decision support for scientific land resource management.

Under the background that economy and urbanization of China are gradually entering the stage of high-quality development, clarifying the influence of economic development on urban livability is of significant academic and practical value. In this paper, regarded as one "factor", livability was introduced into the research framework of production function, and a theoretical model of the impact of economic development on urban livability was established. Based on the panel data of 40 cities in China from 2005 to 2019, the System GMM, panel threshold model and other methods were further adopted to carry out an empirical analysis. The results show that: (1) The livability level of large and medium-sized cities in China from 2005 to 2019 has been rising generally, but they present obvious characteristics of dimensional and spatial differentiation. (2) In general, economic development has an inhibiting effect on the improvement of urban livability, but this logical effect shows obvious heterogeneity in different time periods and diverse city scales. This inhibitory effect is more significant for the cities before entering the new normal phase of economy, and large-scale municipalities and economically-developed provincial capitals (namely Class-A cities). (3) There are significant threshold effects in the impact of economic development on urban livability, where the threshold variables are income level and economic development. With the increase of city dwellers' income, this effect presents an inverted N-shaped nonlinear feature. When the development of economy makes the average wage of employees between 60000 and 80000 yuan, economic development can significantly improve urban livability. Also, there is a significant single threshold inhibitory effect when economic development is taken as a threshold variable. However, its negative impact shows a law of diminishing marginal efficiency. In addition, a similar threshold effect is found in smaller-scale Class-B cities. The findings of this research can provide some insights for urban planners and policymakers in both China and vast developing countries to understand better the relationship between economic development and urban livability. Finally, according to the research findings, we proposed the corresponding policy enlightenment from both "macro guidance" and "micro action".

This paper reviews a series of policies on Northeast Revitalization which were issued by the central and the local governments from 2003 to 2020. The authors analyze the relevant policies from three spatial dimensions, including the national, the provincial and the municipal levels, and deconstruct the policies in three attributes: hierarchy, type and time series. The analysis of the selected policies is assisted by Python's self-programming in text data mining. Lastly, the authors evaluate the effects of regional economy and the reformation of state-owned enterprises driven by the policies of Northeast Revitalization. The results indicate that: (1) The central government, the provincial-level regions and the prefecture-level cities have issued a series of policies in response to the Northeast Revitalization, forming a complex policy system with multi-type, multi-level and multiple time nodes. (2) The formation and transformation of Northeast Revitalization policy system has the characteristics of stability, continuity, timeliness and regionality. (3) The policies of Northeast Revitalization has a positive effect on the growth of reginal economy in a long run, however, the local governments highly depend on the policies, which leads to significant economc growth in the short term, but poor persistency for long-term development. (4) With the support of the policies, the reform of state-owned enterprises is strengthened and innovative achievements are made, yet, the challenges in the development of techniques cannot be neglected.

Relocating government seats is a city administrative strategy for optimizing space and structural organization, and for promoting economic development through re-allocation of urban space resources. However, there is a disconnect between the central government's current cautious attitude toward government relocation, and local government's actual benefits from such relocation, which reinforces the demand for policy evaluation research. Previous studies paid insufficient attention to the impact of urban government relocations on the overall economy, and lacked empirical evidence of large samples. This paper uses China's urban panel data from 1996 to 2016, and adopts a Difference-in-Difference approach based on Propensity Score Matching (PSM-DID) to examine the effect of urban government relocation on economic growth. The results show that urban government relocations significantly promote urban economic growth. However, other urban characteristics will also affect the economic growth effects of relocation, and produce heterogeneous results. Among these, urban characteristics such as migration distance, economic development level, fixed asset investment rate, and government intervention amplify the economic growth effect of relocation, while the growth of construction land reduces it. The size of the city, on the other hand, has no significant regulating effect on the economic growth generated by government relocation. From the perspective of the time, the long-term economic growth created by urban government relocation increases after about 7 years of relocation. The findings of this paper not only support the positive effect of urban government relocations on a city's economic growth, and provide an academic basis for optimizing administrative divisions adjustments, but also provide an important resource for the governments in considering the relocation plans for local administrative centers.

A clear ecological restoration zoning of territorial space is the prerequisite and foundation for the orderly implementation of land remediation and ecological restoration projects. Chongqing is the last gateway to the ecological barrier of the upper reaches of the Yangtze River, with a prominent strategic position in the ecological security pattern of China. Taking Chongqing as an example, this study explored the framework of ecological restoration zoning based on the adaptive cycle model, constructed an index system to evaluate the spatio-temporal characteristics of the three-dimensional attributes of potential, connectedness and resilience of the city's territorial space system, identified the adaptive cycle phase of each county, and discussed its ecological restoration of territorial space. The results show that: (1) The spatial distribution of three-dimensional attributes in the study area from 2000 to 2020 presents a pattern of high in the east and low in the west. Most of the counties in Chongqing are in the reorganization phase, exploitation phase and coordinated exploitation phase, a few are in the conservation phase, and no county has yet entered the release phase. (2) Ecological restoration zoning of the city includes 4 zones and 9 subzones. In general, the ecological restoration zone focuses on systematic ecological restoration projects in built-up areas and strengthen comprehensive environmental improvement and treatment efforts; the ecological enhancement zone should gradually improve the implementation standards of ecological protection and restoration projects, optimize the coordination of various ecological elements, and enhance comprehensive ecological benefits; the ecological control zone should limit the intensity of territorial space development and reduce the negative impact of human activities on ecosystems; the ecological conservation zone should optimize the functions of natural ecosystems and strengthen the management of ecological reserves and the solution to ecological problems.

International trade of agricultural products plays a crucial role in national food security in China. Using the methods of normalized trade balance index, Hirschman index, Hilbert curve, ridge regression, and visualization analysis, this paper analyzes the evolution of China's agricultural trade structure from 1992 to 2020 and its relationship with food security. This paper finds that: (1) The pattern of China's agricultural trade changed significantly from 1992 to 2020, characterized by an increasing dependency on imports. The trade of agricultural products, such as pork, beef, corn, sorghum, and rapeseed, shifted from exports to imports. The rapid growth of imports which directly increased domestic food supply has improved food security in China. (2) The imports of agricultural products present a combined effect of product structure and spatial structure. As a result, the imports of key agricultural products are likely to be affected by the trade policy changes in some countries such as the United States and Australia. In contrast, the exports of agricultural products show a low concentration. The trade with countries and regions along the Belt and Road has dramatically expanded the exporting destinations, and significantly lowered the geographical concentration of exports. A low level of concentration has helped to ensure the economic benefits of exports and stabilize agricultural production in the export sector. (3) Agricultural production in China has showed an inclination to reduce the production of some imported products. Coupled with the highly concentrated import structure, domestic agricultural production and food security will be vulnerable to external shocks. Based on the findings, it is suggested to optimize the import and export structures of agricultural products, and guide proper agricultural production while adhering to trade openness.

With the signing of the Regional Comprehensive Economic Partnership (RCEP), Asian integration has entered a new stage. Two major issues need to be clarified: what are the characteristics of interconnectivity between ports in the "Asian Mediterranean" over time, and what are the patterns of port connectivity in the process of trade integration. This paper uses maritime route data from 1890 to 2008 to construct a dataset of shipping networks with long time series. The characteristics of shipping connectivity in this region are studied from two dimensions of port function and shipping connectivity, and the Michael Porter Diamond Model is adapted to analyze the evolutionary mechanism. The main conclusions are drawn as follows: (1) From the perspective of the strength and breadth of connection between ports, Japanese ports rose to prominence before World War II. After that, Singapore and Hong Kong maintained their hub status for a long time. Since the reform and opening up in the late 1970s, and particularly after China became a member of the WTO in 2001, the volume of traffic in Chinese ports has grown rapidly. (2) In terms of the transshipment function, there was little difference in the transshipment capacity of ports before World War II. After World War II, Singapore, Hong Kong, and Busan successively become the three major transit hubs in the southern, central, and northern parts of the Asian Mediterranean. (3) The long-term port connection has gone through four stages: the disorderly distribution of shipping lines (from the 1890s to the 1920s), the formation and development of the maritime network (after the 1930s), the emergence of multiple hub ports (since the 1950s), and regional port cluster development (since the 1990s). (4) Factor conditions and management policies facilitate the long-term stability of ports. Port prosperity is driven by demand conditions and external opportunities. Replacement of managers profoundly impacts port organization patterns. Port connectivity is influenced by enterprise strategies and inter-port competition. The long-term dynamic law shows that in general, the port network tends to move from fragmentation to integration. A small number of ports have long been ranked in the first echelon due to their superior geographical locations on land and sea. The post-developed ports and non-hub ports should be actively integrated into the pattern of route interconnection.