From Concentration to Polycentric Embedding: Modeling the Spatial Restructuring of Low-Threshold Urban Food Economies Using Multi-Temporal POI Data in Xi’an

Rapid metropolitan expansion reshapes not only land-use patterns and infrastructure networks but also the spatial organization of micro-commercial systems embedded in everyday urban life. While large-scale retail restructuring has been extensively examined, the mechanisms underlying micro-commercial spatial transformation remain insufficiently theorized, particularly in rapidly urbanizing contexts. This study investigates the spatio-temporal restructuring of a representative low-threshold urban food economy in Xi’an between 2014 and 2024. Using multi-temporal point-of-interest (POI) data, kernel density estimation, and spatial Shannon entropy, we model changes in intensity gradients, distributional complexity, and zonal differentiation across morphologically distinct urban belts. The results reveal a systematic transition from centralized concentration toward polycentric embedding, characterized by the relocation of clustered micro-commercial activities along metro corridors and within emerging residential zones. Unlike classical decentralization, which implies outward diffusion, polycentric embedding reflects the infrastructural and demographic re-anchoring of clustered economic activities within newly stabilized urban territories. Entropy analysis further indicates increasing structural heterogeneity in metropolitan expansion zones, while historic cores retain symbolic concentration but exhibit declining structural dominance. These findings demonstrate that micro-commercial systems reorganize not through random dispersion, but through infrastructure-mediated embedding processes driven by metro expansion, residential aggregation, and institutional anchoring. By integrating longitudinal POI data with spatial complexity metrics, this study advances a replicable analytical framework for linking micro-scale commercial dynamics with metropolitan structural transformation. The study contributes to urban theory by reframing low-threshold economic systems as embedded infrastructures of everyday urban reproduction and provides planning insights for fostering resilient and spatially balanced commercial ecosystems under rapid metropolitan growth.