Urban expansion brought stress to food security in China: Evidence from decreased cropland net primary productivity
This paper in the Science of the Total Environment journal assesses the impact of urban expansion on the Cropland net primary productivity (CNPP) in China from 1992 to 2015 in a spatially explicit manner. CNPP is a crucial indicator of grain productivity and food security. However, assessments of the impact of urban expansion on the CNPP in China have been inadequate owing to data limitations. The authors first obtained the CNPP before urban expansion between 1992 and 2015 in China using the Carnegie-Ames-Stanford Approach (CASA) model. The authors then assessed the impact of urban expansion on the CNPP from 1992 to 2015 at multiple scales (the whole country, agricultural zones, and urban expansion hotspots) by combining the CNPP before urban expansion with the urban land coverage time series extracted from multi-source remotely sensed data. The authors found that the total loss of the CNPP due to urban expansion from 1992 to 2015 was 13.77 TgC, which accounts for 1.88% of the CNPP before urban expansion in China. Therefore, the authors concluded that rapid urban expansion from 1992 to 2015 caused stress to China’s food security. They conclude that it is still vital for China to effectively protect cropland to improve the urbanization level to 60% by 2020.