Differences in Winter Wheat Net Primary Productivity in Response to Agricultural Drought

Drought is a globally prevalent and economically devastating natural disaster that significantly affects agricultural production. The North China Plain (NCP) comprises China’s largest cultivation region for winter wheat, Nevertheless, the impact of seasonal drought on the net primary productivity (NPP) of winter wheat in the NCP has not been fully elucidated. Therefore, this study evaluated the impacts of different drought types on NPP losses to reveals variations in farmers' strategies for coping with drought. In this paper, we divided the NCP into humid area (HA) and semiarid area (SA), using the palmer drought severity index (PDSI) to represent natural agricultural drought (NAD) and the vegetation health index (VHI) to signify actual agricultural drought (AAD), with winter wheat NPP losses serving as an indicator of drought impact. Results showed that NPP losses in both HA and SA increased from the 1980s to the 2000s, and then gradually decreased in the 2010s. Spatial analysis indicated that winter wheat was more sensitive to NAD in HA than in SA, with the strongest correlation between NPP and VHI observed in March in HA and in April in SA. Despite the inconsistency between PDSI and VHI, the responsiveness of winter wheat to drought heightened with the advancement of phenological development, suggesting that farmers did not adopt suitable irrigation strategies based on actual climatic conditions. Although precipitation remained a primary driving factor for NAD, temperature and radiation gradually emerged as the dominant causes of AAD. Our results contribute to a better understanding of regional carbon cycling and the improved management of winter wheat production.