Modeling different urban change trajectories and their trade-offs with food production in Jiangsu Province, China

Urban areas in China have expanded rapidly in recent decades, which mainly resulted in the conversion of fertile cropland. As the growth of urban areas is likely to continue in the next decades, there is a need for detailed assessments of urbanization impacts on food production. However, most land use models cannot simulate different types of urban change trajectories, such as expansion and densification, which constrains their capacity to inform such assessments with sufficient detail on the patterns of urbanization. In this paper, we present a land use model that represents multiple types of settlements, which allows to simulate multiple different urban change trajectories. We applied this model to Jiangsu Province, China, and assess the impact of projected urban development between 2015 and 2030 on cropland area and crop production. Results show that population growth is accommodated by different urban change trajectories, depending on the absence or presence of land use policies to maintain food security. In the absence of policies, population growth mainly leads to urban expansion, yielding losses in both cropland area and crop production. Implementing strict cropland protection policies leads to more urban densification and all population can be accommodated without a net loss of cropland. Yet, crop production decreases in this scenario as the most productive croplands are still converted and compensated by less productive areas. Protecting crop production instead leads to a small loss in cropland area combined with cropland intensification and different types of urban change, but maintains the total crop production. These results show the relevance of more nuanced representation of urban development in land use models in order to inform land use policies.