Reliable and continuous data on China's urban-rural population migration and mobility provide a fundamental basis for analyzing demographic transition and its spatiotemporal dynamics, and offer critical support for evidence-based policymaking on the two-way flow of population, resources, and labor between urban and rural areas and on integrated urban-rural development. This paper systematically reviews the current data foundations and limitations of research on China's urban-rural population migration, and identifies the challenges and opportunities associated with census data and big data. The findings show that existing research still faces evident data shortages, including insufficient attention to urban-rural geographic distinctions, limited use of flow data, inadequate fine-grained origin-destination analysis, weak examination of migration-flow structures, and a lack of micro-scale studies. Census-based migration research also suffers from limited spatiotemporal comparability, as reflected in repeated revisions of urban–rural statistical standards, fluctuating and discontinuous collection scales of origin information, coarse spatial resolution, and related problems. The integration of population census data, big data, and artificial intelligence brings new opportunities for studying urban-rural population migration and mobility. AI can help integrate multi-source data, improve spatial precision, generate flow data, and support deeper analyses, such as decomposing migration-flow structures and uncovering hidden associations.

The Greater Food Concept reconfigures the relationship among humans, food, and land. Against the backdrop of tightening resource constraints and growing ecological pressures, traditional supply–demand frameworks are insufficient to explain the complex socio-ecological interactions of food systems. Taking the Greater Food Concept as its theoretical point of departure, this paper constructs an analytical framework for the "human-food-land" relationship and traces its historical evolution in Chinese society. The findings show that this relationship has evolved from primitive "coherence" to industrial "imbalance" and is now moving toward "harmonious symbiosis." The Greater Food Concept goes beyond linear, production-oriented thinking by promoting diversified food supply, optimized demand structures, and coordinated development of food quantity, quality, ecology, and nutrition security. At the macro-system level, it reshapes the logic of food exchange between human society and ecosystems, thereby advancing sustainable food-system transformation and balancing resource utilization with human well-being. This relationship also embodies the Chinese philosophical ideas of "the unity of humanity and nature" and "following the way of nature," offering a theoretically enriched framework for global sustainable development.

During China's economic transition, declining population growth and regional re-differentiation have accelerated urban-rural shrinkage in major urban regions. Focusing on the connotations of "phenomenon-process-effect", this study constructs a two-step assessment framework for identifying urban-rural shrinkage from the perspective of urbanization, and examines its spatio-temporal differentiation and correlation with urbanization. Taking 149 county-level units in the Beijing-Tianjin-Hebei region from 2000 to 2020 as the research objects, the study conducts empirical analysis using population census, statistical yearbook, land-use, and nighttime light data. The results show that urban-rural shrinkage is characterized by spatial agglomeration, inertial development, and self-limitation, with the overall pattern shifting from scattered shrinkage to more extensive shrinkage. At the county level, urban-rural shrinkage is closely associated with urbanization: in terms of scale, the degree of shrinkage affects the direction of urbanization change; in terms of quality, shrinkage exerts a stronger negative effect on urbanization quality. As China enters the middle and late stages of urbanization transition, the stabilizing mobility of population between urban and rural areas and the weakening of on-site urbanization have made population, land-use, and industrial factors more active in shaping county-level shrinkage. This study provides evidence for governing urban-rural shrinkage and improving urbanization quality.

Promoting spatial collaborative agglomeration between high-tech manufacturing and producer services helps improve resource allocation and industrial upgrading. Taking Tianjin as a case, this study uses township- and subdistrict-level enterprise data to examine the spatio-temporal characteristics and influencing factors of collaborative agglomeration among start-ups in the two sectors. Methods include kernel density estimation, an industrial collaborative agglomeration index, bivariate spatial autocorrelation, the geographic detector, and multiple regression. The results show that such agglomeration has occurred within Tianjin. The spatial dependence between the two sectors has strengthened, but follows an inverted U-shaped pattern: areas with excessive high-tech manufacturing density become less attractive to producer service start-ups. Knowledge stock, entrepreneurial carriers, innovation ecosystem, industrial structure, wage level, and their interactions are key drivers, especially when combined with locational factors. However, the rapid decline in the secondary-industry share, industrial spatial differentiation, separation between production and urban functions, and jobs-housing separation hinder further agglomeration.