Grain self-sufficiency capacity in China's metropolitan areas under rapid urbanization: Trends and regional differences from 1990 to 2015

Urbanization brings significant changes to the urban food system. There is growing attention to food self-sufficiency in metropolitan areas for the concern of greenhouse gas (GHG) mitigation in food transportation. In China, grain self-sufficiency in metropolitan areas is also an important issue for grain security and involves coordination among contradictory policy goals. Based upon a comprehensive statistical analysis of 70 metropolitan areas in mainland China, we investigated the regional differences in the trends of grain self-sufficiency capacity in these areas from 1990 to 2015. The findings show a trend of decline in 3/4 of metropolitan areas, mainly located in the rapidly urbanizing eastern coastal areas and in theWest. The increase of self-sufficiency mainly occurred in the North, in areas either specialized in grain production or originally low in grain self-sufficiency. The enlarging contradiction of decreasing supply and rising demand explained the sharp decrease in self-sufficiency, while the increase in self-sufficiency was due to the increase in supply. Land productivity contributed more significantly than land availability to supply change. There was a tradeoff between urban expansion (rather than economic growth) and grain production in metropolitan areas. Our results provide implications to future research and policy-making for grain production management in China's metropolitan areas.