Fringe Belts in Guangzhou: Morphological Evolution and Value Assessment

Fringe belts serve as the “growth rings” of urban expansion, bearing witness to the historical development and evolution of cities. Previous studies on urban morphology often focused on qualitative research, lacking quantitative measurement of various values in the context of high-density megacities. This study uses the main urban area of Guangzhou as a case study, reconstructs morphological periods based on the city’s history of over 2000 years, combines multi-source spatiotemporal data to accurately identify natural and artificial fixation lines, and scientifically defines and divides the spatial ranges of four urban fringe belts: inner, middle, middle-outer, and outer. This study has constructed a quantitative measurement framework integrating function and space, relying on remote sensing land surface temperature inversion, land use models, nighttime lights, and POI data to determine the ecological, economic, and social functions of the fringe belts in Guangzhou. The results demonstrate that (1) Guangzhou fringe belts exhibit distinct hierarchical spatial expansion pathways: leapfrog expansion, linear extension and stratified renewal. (2) Fringe belts constitute composite spaces with notable ecological value, exhibiting relatively favorable local thermal environmental characteristics within high-density built-up environments. Moreover, the natural patches contained within fringe belts demonstrate strong morphological resilience. (3) The economic and social functions of fringe belts strengthened while exhibiting uneven spatial changes, while spatial functions shifted from predominantly production and institutional uses toward more diverse urban functions. Nighttime light intensity increased overall, with widening absolute differences among units but declining relative dispersion, indicating overall brightening alongside persistent spatial variation in nighttime illumination. This work creates a novel paradigm for value evaluation, adapting Western urban morphological theory to a Chinese megacity while offering an effective tool for urban resilience and landscape regulation.