Cultivated land has been one of the most important resources for national food security. While cultivated land fragmentation has restricted modern agriculture in the hilly and mountainous regions of Southwest China. According to the man-land relationship territorial system theory and multidimensional perspective of nature-economy-society, this study attempted to construct a theoretical framework of status evaluation-effect testing-mechanism analysis. Hechuan District of Chongqing Municipality was selected as the research area. Three-period survey data was collected from 326 villages from 2014 to 2024. An evaluation index system was also conducted for cultivated land fragmentation. Panel multidimensional fixed- and mediation-effect models were employed to measure the degree of cultivated land fragmentation. A systematic analysis was conducted to examine the impact mechanism and heterogeneity of cultivated land fragmentation on villages’ income. The results indicate that: 1) The high degree of cultivated land fragmentation was observed from 2014 to 2024, with the fragmentation index pattern of initial increases followed by decreases. Notable regional differences narrowed gradually, with the ratio of the maximum to minimum decreasing from 1.99 to 1.83. Meanwhile, the spatial distribution was characterized by two primary zones, one secondary zone, and higher levels in the north than in the south, namely the northwest and northeast regions as the primary centers, the central region as the secondary center, and the northern region higher than the southern region. 2) Cultivated land fragmentation significantly inhibited villagers' income growth. Specifically, a one-percentage-point increase in the degree of cultivated land fragmentation led to a six-percentage-point decrease in villagers' agricultural operating income. A series of verifications included the dependent variables, the independent variables, the sample scope, and the control variables. 3) Cultivated land fragmentation suppressed villagers' income growth, such as high agricultural production costs, the promotion and application of agricultural machinery, and low land transfer. 4) There was the heterogeneity impact of cultivated land fragmentation on villagers' income growth over household attributes, village attributes, and village topography, particularly for households lifted out of poverty, poverty-stricken villages, and hilly areas. 5) Finally, the measures were proposed for cultivated land fragmentation, including industrial support for households lifted out of poverty, differentiated land consolidation, and industrial models under local conditions. The findings can provide theoretical support to manage farmland fragmentation for the common prosperity in the hilly and mountainous areas of Southwest China in modern agriculture.

Rural settlements are the basic spatial units to implement the rural revitalization strategy. However, the weak links of rural settlements are found in the ecologically vulnerable areas, particularly for the coordinated and high-quality development of regional ecology and economy. Taking Tianzhu County in Guizhou Province as the study area, this study aims to analyze the evolution, influencing factors and dynamic variation in the spatiotemporal patterns of rural settlements in the ecologically vulnerable areas from 2012 to 2022 using "Scale-Space-Morphology" approach. The rural settlement patches and administrative villages were then taken as the research objects. Three research nodes were selected in 2012, 2017 and 2022. The optimal parameters were obtained, according to the average nearest proximity index, landscape pattern index and geographical detector. The research procedures were as follows. Firstly, the scale, spatial distribution and morphological pattern of rural settlements were characterized by landscape pattern index, nearest distance value and morphological dimension. The spatiotemporal pattern and evolution of rural settlements were identified in the ecologically fragile areas. Secondly, the optimal scale was obtained for the dispersion of different influencing factors using spatial dispersion and quantitative combination. Finally, the geographic detector model with optimal parameters was used to identify the influencing factors and dynamic variation in the scale, spatial distribution and morphological pattern of rural settlements in the ecologically fragile areas. The results show that: 1) The scale pattern of rural settlements in the ecologically vulnerable areas shared a trend of increasing and then decreasing, which was mainly dominated by micro settlements and small settlements. But the average scale was much higher than the national level. The scale of rural settlements was gradually shifted from the quantitative to qualitative enhancement; 2) There was a significant autocorrelation in the spatial pattern of rural settlements in the ecologically vulnerable areas. The degree of spatial agglomeration was gradually increasing. The layout shared the “four-week to middle core agglomeration” trend, that is, the central and southern regions were formed two larger and multiple smaller agglomeration areas; 3) The outstanding fractal features were observed in the rural settlements in the ecologically vulnerable areas. The evolution of morphological index shared a trend of first rising and then decreasing. But there was the outstanding variation in the stage increase on the whole, together with the simple morphology; 4) There were the unique influencing factors on the evolution of the “scale-space-morphology” pattern of rural settlements in the ecologically vulnerable areas. Generally, there was a trend of transformation from natural conditions to social economy and policy. Among them, the relocation sites for poverty alleviation, transportation accessibility, village and town planning and distance from town centers were the main influencing factors on the spatial and temporal evolution of rural settlements. Especially, the relocation sites for poverty alleviation, village and town planning were defined as the continuous enhancement type. Finally, the targeted recommendations were made to strengthen the territorial spatial planning, ecological protection, the spatial pattern of rural settlements in the production and living of farming households.