Spatial-temporal patterns of urban expansion by land use/ land cover transfer in China

Urbanization has accelerated in China, resulting in a noticeable conflict between urban expansion and land use/land cover (LULC). This issue can exacerbate ecological and developmental problems in urban neighborhoods, so it is crucial to explore the relationship between long-term urban expansion and LULC spatial and temporal transitions. We first defined urban built-up areas in terms of human economic activity and then used spatial measures to examine urban expansion and spatio-temporal changes in 25 LULC classes by analyzing 369 cities across China. Our findings indicate that China's urban built-up areas expanded 9.1 times between 1995 and 2020, with the fastest growth rate occurring between 1995 and 2005 at about 16%. We observed a negative association between China's urban built-up area and dry farming land, forests, and grassland in that order, with grassland exhibiting the weakest correlation. The negative correlation between urban built-up areas and paddy fields became positive after 2010, while the positive correlation with reservoirs and canals became negative after 2015. This study utilized spatial measures to demonstrate the spatial heterogeneity of urban expansion in China and explored the extent to which different LULC area changes explained urban expansion. We provide a reference for decision-making efforts on land management and sustainable use in urban areas.