Urban expansion and agricultural land loss in China: A multiscale perspective

China's rapid urbanization has contributed to a massive agricultural land loss that could threaten its food security. Timely and accurate mapping of urban expansion and urbanization-related agricultural land loss can provide viable measures to be taken for urban planning and agricultural land protection. In this study, urban expansion in China from 2001 to 2013 was mapped using the nighttime stable light (NSL), normalized difference vegetation index (NDVI), and water body data. Urbanization-related agricultural land loss during this time period was then evaluated at national, regional, and metropolitan scales by integrating multiple sources of geographic data. The results revealed that China's total urban area increased from 31,076 km² in 2001 to 80,887 km² in 2013, with an average annual growth rate of 13.36%. This widespread urban expansion consumed 33,080 km² of agricultural land during this period. At a regional scale, the eastern region lost 18,542 km² or 1.2% of its total agricultural land area. At a metropolitan scale, the Shanghai-Nanjing-Hangzhou (SNH) and Pearl River Delta (PRD) areas underwent high levels of agricultural land loss with a decrease of 6.12% (4728 km²) and 6.05% (2702 km²) of their total agricultural land areas, respectively. Special attention should be paid to the PRD, with a decline of 13.30% (1843 km²) of its cropland. Effective policies and strategies should be implemented to mitigate urbanization-related agricultural land loss in the context of China's rapid urbanization.