Exploration of the impact of polycentric spatial structure on urban growth types from a generalized perspective

Addressing the limitations of conventional narrow-sense polycentric spatial structure research and the practical demand for intensive growth in sustainable urban development, this study adopts the generalized polycentric spatial structure as its analytical framework and investigates its influence on urban intensive growth. Drawing on a sample of 287 prefecture-level cities nationwide, the study integrates nighttime light (NTL) data and LandScan population raster data to construct the urban nighttime light (UNL) composite agglomeration index, applies exploratory spatial data analysis (ESDA) and geographically weighted regression (GWR) to delineate urban primary-secondary centers, and classifies four generalized polycentric morphologies along two orthogonal dimensions, namely the number of primary centers and the agglomeration-dispersion degree of secondary centers. A patch-based urban index (PBUI) is further developed to identify urban growth types from 2014 to 2024. The analysis identifies 205 generalized polycentric cities in total, and the structural effects exhibit pronounced heterogeneity. Cities with higher agglomeration-synergy levels, specifically the polycentric-synergistic and balanced-symbiotic types, effectively suppress extensive growth in distant suburban enclaves and facilitate intensive urban development. The monocentric-dispersed type exerts only a negligible and statistically insignificant restraining effect on disorderly expansion. The acentric-fragmented spatial configuration tends to generate functional overlap among centers and fragmented resource allocation, thereby exacerbating inefficient and extensive growth. Furthermore, this effect varies by development level: cities with stronger economic foundations and well-established infrastructure demonstrate more pronounced polycentric guidance toward intensive growth, whereas indiscriminate spatial dispersion in less-developed cities depresses land-use efficiency and impedes the realization of intensive growth. This study clarifies the temporal logic through which generalized polycentricity shapes urban expansion, and establishes a reproducible identification framework for generalized polycentric structures alongside compatible expansion measurement indicators. The findings offer empirical support for China’s differentiated formulation of polycentric spatial plans, the regulation of disorderly urban peripheral expansion, and the coordinated promotion of high-quality, intensive land use in both urban and rural areas. They also provide a reference for spatial optimization and sustainable urbanization in developing countries facing analogous challenges.