Rural society, economy, culture and ecology have undergone some significant changes in the transition period from high-speed growth to high-quality development in China, particularly with the rapid industrialization and urbanization. Among them, the rural settlement is one of the indictors in the rural socioeconomic activities, including their multifunctionality. Furthermore, the number, scale and shape of rural settlement vary greatly in the background of the transformation and development of rural society. Therefore, it is very necessary to explore the coupling relationship between functional diversity and settlement evolution for the rural revitalization and sustainable development. In this study, a theoretical framework was firstly constructed for the functional diversity and rural settlement evolution in mountain areas. The study area was taken as the Fengjie County in the hinterland of the Three Gorges Reservoir Area. 21 indicators were selected from the three dimensions of production, living and ecological function. Four indices of landscape pattern were selected as the indicators from four dimensions of area, shape, density and aggregation. Secondly, the comprehensive evaluation model was used to calculate the composite index of rural functional diversity and rural settlement evolution. The coordination degree model, spatial autocorrelation model and elasticity coefficient model were combined to explore the coupling relationship between rural functional diversity and rural settlement evolution. Finally, the driving mechanism was determined using geo-detectors. The policy suggestions were also proposed, according to the regional conditions. The results show that: 1) The average composite indexes of rural functional diversity and rural settlement evolution increased from 0.222 to 0.281 and 0.184 to 0.262 during the study period, respectively, indicating a faster growth rate. The coupling coordination degree of the two systems increased year by year. The number of dysfunctional towns decreased with the patter of "low in the west and high in the east, low in the south and high in the north". 2) There was a positive correlation between rural functional diversity and the evolution of rural settlements at the township scale from 2000 to 2020. There were the outstanding spatial agglomeration. The high agglomeration areas were mainly concentrated in the outskirts of the central towns, such as Yong'an, Yu Fu and Kui Men Street. 3) According to the increase-decrease relationship of the composite index, the townships were categorized into four coupling modes: vibrant, declining, transforming and traditional type. 4) Socio-economic parameters (such as population density, per capita GDP, and intensity of human activity) were the main driving factors. Most of the interactions among the driving factors were nonlinearly and two-factor enhanced properties. The interactive driving factors with greater explanatory power were found in the land use degree/cultivated land area, number of rural employees/transportation convenience, human activity intensity/cultivated land area. Consequently, it is necessary to promote the positive interaction between rural functions and rural settlements in the process of rural revitalization. The adaptability of rural settlement transformation and development also need to improve for the sustainable and healthy rural development.

Land use transformation can be clarified under the human-land coupling system, in order to promote the high-quality development and sustainable land use. In this study, the coupling coordination degree model, landscape index and binary logistic regression were adopted to explore the land system evolution and influence mechanism in the hinterland of the Three Gorges Reservoir Area from 2000 to 2020. The transformation of human-land coupling land system was also summarized in the context of human-land coupling, in terms of quantity, landscape pattern, and functional form. The results show that: 1) The intensity of human activities were a gradual increase to decrease with a consequent evolution in the human-land coupling relationship. In general terms, the human-land relationship showed a gentle trend towards a coordinated type of change. There was the differential evolution of spatial distribution, which was tended to be coordinated in the central and northeastern, the northern was tended to be antagonistic, and there was no outstanding change in the southern. 2) The human-land coupling land system shared the outstanding change in the quantity, landscape pattern and function after the construction of the Three Gorges Project, particularly on the returning cultivated land to forest and grassland. The cultivated land decreased in the antagonistic and the imbalanced area, part of which was the abandoned land. The woodland increased restoratively in the antagonistic area. But there was the fluctuating evolution in the imbalanced area, where the first increased and then decreased. whereas, the orchard was expanded significantly in the coordinated area. The degree of patch fragmentation was improved to be regular landscape pattern. Land systems were evolved from the mono-functional dominance to multi-functional. 3) There was the diversified transformation of the human-land coupling land system in the study area. Patterns were also summarized as follows. The antagonistic area with woodland increased in the quantity form, while the patches were aggregated with the ecological function and irregular form of landscape pattern; The imbalanced area with the woodland decreased, whereas, the patches were aggregated to regularly and ecologically orient; The coordinated area with orchard expanded, while the patches were overall aggregated regularly, ecologically and economically. 4) Distance and topography were the influencing factors on the evolution of land system. The cultivated and abandoned land decreased, whereas, the woodland increased, as the distance from the settlement and the topographic relief increased. The orchard decreased with the increase of elevation. In addition, the interaction among the dominant factors was superimposed on the land system. The development mode of human-land coupling relationship and land system transformation in the Three Gorges Reservoir Area can be of practical significance to promote the rational use of land resources and the coordinated development of human-land in mountainous areas.