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Changes in cultivated land in China are related to food security for nearly 1.4 billion people. Administrative ruling has decomposed the goal of cultivated land protection in China and implemented it from top to bottom, so that cultivated land data have nested attributes. Although related research on cultivated land changes has achieved fruitful results, these studies have neglected the scale effect created by the nested structure of cultivated land data, and it is easy for the policy to lose its effect in scaling. A two-layer linear model of the hierarchical linear model is constructed in this paper based on spatial autocorrelation and scale variance analyses to analyse the different spatial scales for cultivated land changes and reveal the interaction mechanism of the driving factors at different spatial scales. The results show the following: (1) The smaller the spatial scale of the study area, the easier the spatial correlation of the cultivated land quantity distribution. (2) An analysis of the driving factors of cultivated land change in Chongqing finds that 33.80% of the differences are from the functional block scale and 66.20% are from the district or county scale. (3) We found that the spatial scale has a certain impact on the effectiveness of the driving factors of cultivated land changes. Large-scale driving factors will change the correlation between small-scale driving factors and cultivated land change. In the future, the problem of scale effects should be considered in the field of cultivated land management, the effects of different driving forces at various scales should be considered and the scientific decomposition of cultivated land protection tasks according to the spatial scale should be carried out to improve the efficiency of the protection of cultivated land. [ABSTRACT FROM AUTHOR]

Urban construction land-use expansion is an important topic in the field of land-use change research. In the present study, the temporal and spatial changes of urban construction land use in the Chongqing urban area are analyzed, based on land-use maps from 1975, 1987, 1995, 2000, and 2010. Using gradient analysis, the study area was divided into nine buffer zones and eight quadrants. The study analyzed the compactness of the urban construction land in different buffer ranges and different directions, and further fitted the compactness degrees and different gradients. The results indicated that there was a rapid growth of urban construction land use in the Chongqing urban area in the period of 2000-2010, and the land use for urban construction sharply increased at an average annual rate of 5.69%. The expansion pattern showed a spatial mode of one center and multiple subcenters. Furthermore, although the key regions (the fastest-growing regions of urban construction land) of urban expansion showed higher compactness degree than the nonkey regions (the slowest-growing regions of urban construction land) of urban expansion, the compactness degrees were decreasing in the key regions but increasing in the nonkey regions. Specifically, the urban construction land had three highly compact zones in the buffer radius gradient-zones of radius 5, 25, and 40 km-and the compactness degrees gradually increased. When analyzed by the quadrant gradient of buffers, quadrants 45-90° (WNW), 90-135° (WSW), and 315-360° (NNE) were the key regions of urban expansion, and quadrants 225-270° (ESE) and 270-315° (ENE) were the nonkey regions. In addition, the change in compactness degree was highly correlated with changes in the buffer radius and quadrant azimuth. [ABSTRACT FROM AUTHOR]