Dynamic Identification and Evolution of Urban-suburban-rural Transition Zones Based on the Blender of Natural and Humanistic Factors: A Case Study of Chengdu, China

Urban-suburban-rural (U-S-R) zones exhibit distinctive transitional characteristics in interaction between human and nature. U-S-R transition zones (U-S-RTZ) are also highlighting the function diversity and landscape heterogeneity across territorial spaces. As a super megacity in western China, Chengdu’s rapid urbanization has driven the evolution of U-S-R spaces, resulting in a sequential structure. To promote the high-quality spatial development of urban-rural region in a structured and efficient manner, it is essential to conduct a scientific examination of the multidimensional interconnection within the U-S-RTZ framework. By proposing a novel identification method of U-S-RTZ and taking Chengdu, China as a case study, grounded in a blender of natural and humanistic factors, this study quantitatively delineated and explored the spatial evolutions of U-S-RTZ and stated the optimization orientation and sustainable development strategies of the production-living-ecological spaces along the U-S-R gradients. The results show that: 1) it is suitable for the quantitative analysis of U-S-RTZ by established three-dimensional identification system in this study. 2) In 1990–2020, the urban-suburban transition zones (U-STZ) in Chengdu have continuously undergone a substantial increase, and the scale of the suburban-rural transition zones (S-RTZ) has continued to expand slightly, while the space of rural-ecological transition zones (R-ETZ) has noticeably compressed. 3) The landuse dynamics within U-S-RTZ has gradually increased in 1990–2020. The main direction of landuse transition was from farmland to construction land or woodlands, with the expansion of construction land being the most significant. 4) R-ETZ primarily focus on ecological functions, and there is a trade-off relationship between the production-ecological function within the S-RTZ, and in the U-STZ, production-living composite functions are prioritized. This study emphasizes the importance of elastic planning and precise governance within the U-S-RTZ in a rapid urbanization region, particularly highlighting the role of suburbs as landscape corridors and service hubs in urban-rural integration. It elucidates to the practical implications for achieving high-quality development of integrated U-S-R territorial spaces.