Spatial reconstruction of rural settlements in the hilly areas of southern China under the guidance of target differentiation

Multiple differentiation and reorganization have occurred in the rural residential areas during urbanization. An accurate classification is of great significance for the types of rural residential areas, in order to determine the different spatial optimization models for rural revitalization and integrated urban-rural development. However, there are quite different natural conditions and development levels of rural settlements in the mountainous and hilly areas of southern China. Taking the Leping City of Jiangxi Province as a typical example, an evaluation system was constructed for the extended source of rural residential areas from four aspects of production-living-ecological function and scale form. The patches were also screened for the advantage of rural residential settlement. An improved gravity model was first established to calculate the spatial interaction and connection degree between the extended source rural settlements. A two-dimensional judgment matrix was then constructed to determine the spatial reconstruction path of extended source rural settlements. Finally, the layout resistance model was constructed to improve the minimum cumulative resistance model. As such, the spatial reconstruction path and strategy were identified for the non-extended source of rural settlements. The results show that: 1) There was a better size and shape of the single patch with the high comprehensive influence of extended source in the residential areas, indicating adjacent to cities and towns. However, there was a scattered spatial distribution of the extended source with a low comprehensive influence, indicating the fragmented landscape characteristic area. 2) The improved gravity model demonstrated that the gravity value was between 0.007, 1.8 for the extended source rural settlements. It infers that there were significant differences in the functional radiation and service capacity. 3) The western part of the study area presented the lowest comprehensive and cumulative restriction, while the northern and southern parts were the higher restriction, due to the topography, population, and spatial use regulation. The type Ⅰ (the higher non-extended source settlements) was mainly distributed in the intermountain basin of central and western areas, whereas, the type Ⅲ (the lower settlements) was concentrated in the northern and southern high-altitude regions. 4) The spatial reconstruction paths of rural settlements were divided into four types of optimization modes: suburban integration, village integration, agglomeration promotion, and key cultivation, with an area of 31.92, 654.52, 283.59, and 1 885.82 hm2, respectively. The relationship was then established between the suitable level and expanding influence area of the non-extended source residential area layout under the goal guidance of optimization and smart contraction. Four types of layout strategies were also determined: the key development, scale control, optimization transformation, as well as the relocation and demolition type, with an area of 1 488.91, 3 106.91, 1 113.08, and 172.63 hm2, respectively. 5) A specific case was selected to verify the spatial layout planning of the village system in the Lingcheng District, Shandong Province (2018-2035). A better agreement was then achieved in the reconstruction type, indicating the strong practical significance. A tradeoff was also obtained to balance the mismatch between the path of spatial reconstruction and the development factors in the residential areas, particularly for the better spatial reconstruction. At the same time, this finding can provide a strong reference for the spatial planning of rural residential area in the hilly areas.