Cropland abandonment is a critical challenge for food security and the sustainable use of land resources, especially in the hilly and mountainous regions of southern China. To characterize the spatiotemporal evolution and associated-factor patterns of cropland abandonment in these regions, this study uses Ji’an City, Jiangxi Province, as a case study and develops an integrated framework for abandonment identification and monitoring, predictive-association analysis, relative risk assessment, and zoning management. Using Landsat remote sensing imagery from 1990 to 2024, crop phenological features, and multisource topographic, soil, climatic, ecological, and socioeconomic data, we identified and evaluated long-term cropland abandonment. The results show that, after incorporating phenological features and temporal filtering, annual land-use classification evaluated with spatially separated testing samples achieved a mean overall accuracy of 95.27% and a mean Kappa coefficient of 0.931, and the overall accuracy of cropland abandonment identification reached 91.58%, with a Kappa coefficient of 0.83. Cropland abandonment in Ji’an City showed an overall accelerating trend, with the abandonment rate exceeding 15% during 2020–2021. Spatially, abandonment was more intensive in the west than in the east and more severe in mountainous areas than in plains. Paddy field abandonment was the dominant form of cropland abandonment across the city, whereas dryland abandonment was more limited in extent but showed stronger interannual fluctuations. The predictive-association analysis indicated that tree cover consistently showed high predictive importance for both paddy fields and drylands. Paddy field predictions were more strongly associated with topographic position, surface roughness, and soil conservation, whereas dryland predictions showed stronger associations with aridity and population density. From 1993 to 2023, the model-estimated relative abandonment risk increased, and high-risk areas expanded from deep mountainous regions to low-hill areas. By coupling relative risk levels with associated-factor patterns, we divided paddy fields and drylands into four management zones: core protection zones, dynamic warning zones, integrated improvement zones, and ecological fallow zones. Differentiated management strategies were then proposed for each zone. This study provides methodological support and decision-making evidence for cropland abandonment monitoring, cropland protection, and differentiated land management in the hilly and mountainous regions of southern China.

Identifying ecosystem service (ES) trade-offs and synergies (ESTSs) and their effects provides a critical scientific basis for ecological management. However, the effects of ESTSs are not always direct. To compensate for the limited research on the multidimensional heterogeneity and mediating effects of ESTSs, Jiangxi Province was used as a case study for the analysis of spatiotemporal patterns and heterogeneity in ESTSs. Data from 1990–2020 were assessed from static and dynamic perspectives and from multiple dimensions. The direct and indirect effects of the normalized difference vegetation index (NDVI) and land use intensity (LUI) on ESTSs were also identified. We found that ESTSs were characterized by short-term fluctuations, dynamic changes, and long-term stability. Overall, ESTSs were stronger according to a static perspective than to a dynamic perspective and ESTSs were stronger at a small scale than at a large scale. Spatial heterogeneity in the relationships between and the degrees of ESTSs occurred across different multidimensional zones. The effects of the NDVI on ESTSs were significant, and the heterogeneity of these effects was significant across different dimensions. The influence coefficients were ranked as follows: functional control dimension > horizontal development circle dimension > vertical topographic position dimension. LUI can function as a vital mediator in the influence chain connecting the NDVI and ESTSs and manifests as a significant partial mediating effect. The goal of this study was to explore the empirical application of econometric statistical methods to the impact of ESTSs, thereby providing a foundation for targeted and differentiated ecological management policies and a reference for the governance of ESs in similar regions.