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From dominant edge expansion to increasing infilling: the driving forces behind built-up area fragmentation in Chinese cities


Abstract

While the patterns of urban expansion are often described, a national-scale understanding of how specific expansion processes mechanistically drive changes in urban landscape pattern is notably lacking. Our study conducted a comprehensive analysis of 366 cities across China from 1995 to 2018. We found a clear temporal shift in China’s urban expansion, characterized by dominant edge expansion, a significant increase in infilling, and a decline in leapfrog, robustly supporting the diffusion-coalescence theory at a national scale. Rapid built-up area growth (287.6%) led to widespread landscape fragmentation, evidenced by increased patch density and decreased compactness. Path analysis revealed that infilling expansion could directly reduce landscape fragmentation, while leapfrog expansion and road density exacerbated it. This study highlighted that optimizing the type, not just the scale, of urban expansion is crucial for sustainable spatial planning, offering policymakers practical insights to mitigate landscape fragmentation.

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Data availability

The boundary of 366 cities were based on the China’s 2019 administrative divisions, and collected from National Earth System Science Data Center (http://www.geodata.cn/).

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Acknowledgements

The author would like to acknowledge Michelle Stuhlmacher in DePaul University for her previous work on built-up area extraction, which provided basic technical support for this study. This research was supported by the National Natural Science Foundation of China (Grant No. 42201102).

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Yi’na Hu and Jian Peng designed the study; Yi’na Hu interpreted urban area in China; Yi’na Hu and Tao Hu performed the analyses and wrote the paper and prepared the figures; Jian Peng and Fei Xue revised and edited the manuscript. All authors approved the final version of the article.

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Jian Peng.

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Hu, Y., Hu, T., Xue, F. et al. From dominant edge expansion to increasing infilling: the driving forces behind built-up area fragmentation in Chinese cities.
npj Urban Sustain (2026). https://doi.org/10.1038/s42949-026-00346-9

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