Abstract: This study explores the spatio-temporal changes in vegetation net primary productivity (NPP) across the Beijing-Tianjin-Hebei region based on MOD17A3 data. Univariate linear regression method was employed to analyze the temporal and spatial evolution of vegetation NPP in 20 years (2000-2019). Additionally, this study analyzed the correlation between NPP and climate factors. The results show that vegetation NPP in the Beijing-Tianjin-Hebei region mainly falls within the range of 200-400 gC/(m²·a). The mean and maximum values of NPP exhibited gradual increase from 2000 to 2019, with a peak in both mean and maximum values occurring in 2016 at 385.10 gC/(m²·a) and 908.40 gC/(m²·a), respectively. The area with significantly increased NPP in the region from 2000 to 2019 was found to account for 97.12% of the study area, while the area with NPP decrease mainly occurring in areas surrounding urban centers. Furthermore, the four types of vegetation cover in the region ranking from smallest to largest in terms of NPP mean were as follows: cropland, shrub, grassland, and forest. The study also found that from 2000 to 2019, the stability of NPP in the region was characterized by high-low fluctuations, with lower fluctuations being dominant. Finally, NPP was found to be lowly correlated with the average annual temperature and highly correlated with annual precipitation. The findings can serve as reference for ecological civilization construction, ecological environmental restoration, and management and protection in Beijing-Tianjin-Hebei region.

Key words: net primary productivity (NPP), temporal and spatial evolution, MOD17A3 data, univariate linear regression, correlation analysis, Beijing-Tianjin-Hebei Region