Abstract:

[Objective] With the in-depth implementation of the rural revitalization strategy and the rapid progress of China's urbanization, the urban-rural spatial structure has undergone significant restructuring. Rural settlements, as the fundamental spatial units of rural areas, have witnessed remarkable changes in scale, layout, and function. Accurately identifying their spatiotemporal evolution and clarifying the driving forces is essential for comprehending urban-rural transformation, optimizing territorial spatial planning, and promoting coordinated development. However, current research still has limitations. Many studies primarily concentrate on describing spatial patterns, overlooking the underlying processes and regional disparities. Comparative analyses between different topographic regions, such as plains and hilly areas, are inadequate, resulting in an incomplete understanding of the impacts of terrain. Moreover, investigations into multi-scale and multi-factor driving mechanisms are relatively weak. Therefore, the aim of this research is to systematically uncover the spatiotemporal evolution of rural settlements under various topographic conditions and to quantitatively identify the key drivers shaping these patterns. [Methods] The primary research regions were Laoling City in Shandong Province, representing typical plain terrain, and Yi'an District in Anhui Province, characterized by hilly landforms. This selection fully takes into account how variations in topographic conditions influence the long - term evolution of rural settlement patterns. Based on the remote - sensing mapping results of rural settlements in 2002, 2012, and 2022, a systematic analysis of the spatial distribution characteristics and temporal differentiation of settlement patterns was conducted. Using geographic information system (GIS) spatial analysis as the analytical foundation and integrating methods such as landscape pattern indices, centroid migration analysis, and spatial pattern change detection, the spatiotemporal evolution trajectories of rural settlements were revealed under contrasting geomorphic settings from the perspectives of overall spatial configuration, internal structural features, and dynamic change processes. In addition, the geographical detector model was employed to quantitatively assess ten potential driving factors, including natural environmental conditions, socio - economic development indicators, transportation accessibility, and location - related attributes. [Results and Discussions] On the county scale, in the plain area, the largest patch index increased from 0.88 to 2.46, while the average nearest neighbor ratio (NNR) decreased from 0.99 to 0.90. This indicates that the settlement size expanded, the structure became more centralized, and the degree of clustering continuously strengthened. In contrast, in the hilly area, the patch density (PD) decreased from 9.16 to 2.77, and the NNR increased from 0.50 to 0.69. This suggests that the number of settlements declined and their spatial structure evolved from highly clustered to relatively dispersed. At the village scale, there were significant differences in the evolution trends between the two regions. In the plain area, changes in rural settlement areas were relatively balanced, with similar proportions of villages experiencing expansion and contraction. Settlements mainly exhibited a block - like distribution, extending along roads. In contrast, in the hilly area, the expansion of rural settlements was more pronounced, with over 70% of villages showing an increase in area. Settlements primarily displayed a linear distribution pattern, extending along rivers and valleys. Over the 20 - year period, the driving mechanisms of rural settlement evolution in the plain area shifted from being dominated by natural and economic factors to being dominated by land resource and safety factors. The driving power (q value) of distance to cultivated land and distance to the urban center increased by 0.51 and 0.39, respectively, becoming the main growth factors. In the hilly area, settlement evolution became increasingly constrained by topography, water resources, and geological safety. The driving power of distance to rivers increased from 0.22 to 0.45, and the dominant driving interaction shifted from "cultivated land-scenic spot" to "geological hazard point–scenic spot", reflecting a more complex driving mechanism. [Conclusions] Different topographic regions exhibit distinct spatial pattern characteristics and evolutionary driving mechanisms at both the county and village scales. Rural settlements in plain areas tend to demonstrate higher degrees of clustering, more regular morphologies, and relatively stable evolutionary processes. In contrast, settlements in hilly areas are more scattered and fragmented due to topographic constraints and resource limitations, and their evolutionary processes are more intricate. This study not only deepens the understanding of rural settlement evolution but also offers scientific support for the localized development of smart agriculture and the reconstruction of rural spatial systems.

Key words: rural settlements, terrain differences, driving factors, spatiotemporal evolution, rural revitalization