Simulation of China's potential rice yields by coupling land system evolution and climate change

Land systems and climate, which are the key elements of agricultural production and key drivers of crop yields, affect the quality of arable land. However, a quantitative model to reveal the mechanism of how potential grain yields are affected by macro-scale arable land evolution and climate change has not yet been developed. In this study, we constructed a Grey Prediction Model-Future Land Use Simulation (GM-FLUS), which combined land system evolution with climate change data, to simulate changes in China's land system over the next 40 years. We improved the Global Agro-Ecological Zone (GAEZ) model, estimated China's potential rice yields and their spatial distribution in the next 40 years under four scenarios (shared socioeconomic pathway SSP1-2.6, SSP2-4.5, SSP3-7.0, and SSP5-8.5) of the Sixth International Coupling Model Intercomparison Project, analysed the spatiotemporal variations in the potential rice yields and their drivers, and provided appropriate suggestions for increasing rice yields. The simulation results indicated an increase in China's potential rice yields during 2020-2060 under the SSP1-2.6 and SSP3-7.0 scenarios and a decrease under the SSP2-4.5 and SSP5-8.5 scenarios. Moreover, China's development strategy of "achieving carbon peaking by 2030 and carbon neutrality by 2060" was similar to the SSP1-2.6 scenario, under which rice yields were relatively stable. Furthermore, under China's arable land protection policy, China's paddy field area will change slightly during 2020-2060, and potential rice yields will be influenced by climate. Under the four climate change scenarios, air temperature increased and was negatively correlated with potential rice yields in main rice-producing regions. Additionally, potential rice yields were positively correlated with precipitation, which increased stably under the SSP1-2.6 and SSP3-7.0 scenarios and decreased under the SSP2-4.5 and SSP5-8.5 scenarios. These results suggest that the development of heat-resistant rice varieties and the implementation of measures that will mitigate the impacts of future temperature increases on rice yields are important for the conservation of paddy fields. Additionally, improving irrigation and drainage facilities is necessary to irrigate drought-prone paddy fields and drain flooded water.