Spatiotemporal Evolution and Suitability Evaluation of Rural Settlements in the Typical Mountainous Area of the Upper Minjiang River: A Case Study of Lixian County, Sichuan Province, China

Under the framework of the Rural Revitalization Strategy, optimizing the layout of rural settlements in mountainous areas and guiding their sustainable development must be based on a deep understanding of the evolution characteristics of rural settlements and suitability evaluations. This study focuses on Lixian County, located in the southwestern part of China, Sichuan Province, as the research area and employs methods such as the average nearest neighbor index, kernel density analysis, and landscape pattern index to analyze the spatiotemporal evolution characteristics of rural settlements in 2000, 2010, and 2020. Additionally, the Maxent model, based on ecological niche theory, is applied to evaluate the suitability of rural settlements. The results reveal the following: (1) Rural settlements in Lixian County exhibit a spatial distribution characterized by “sparser in the west, denser in the east, and a belt-like pattern”, with a clustered distribution trend. The number and area of settlement patches increased, with settlement distribution becoming more centralized, shapes becoming more complex, and connectivity between settlements improving. (2) The area of highly suitable land for rural settlements has decreased annually, with over 85% of the land classified as unsuitable for rural settlement layout. Suitability transitions mostly occur between adjacent levels, and it is difficult for unsuitable land to become suitable. (3) In earlier years, settlement suitability was significantly influenced by the distance to cultivated land, slope, and distance to geological hazard sites. By 2020, however, the distance to roads had become the second most important environmental factor, following the distance to cultivated land. Natural environmental factors, particularly topographic features such as elevation and slope, were found to exert a greater influence than socioeconomic factors in evaluating the suitability of rural settlements in Lixian County. These findings provide a scientific foundation for optimizing rural settlement layouts in mountainous regions, offering valuable insights into rural transformation and sustainable development not only in the upper Minjiang River area but also for reference in other similar mountainous regions.