Abstract: Net primary productivity (NPP) of vegetation is a key component in the carbon cycle and energy flow of ecosystems, influenced by both natural and human factors. As one of key development regions in China, the Jing-Jin-Ji Region (Beijing-Tianjin-Hebei, BTH) should focus on both economic growth and ecological construction. Unveiling the trends of NPP changes and their influencing factors is of great significance for formulating urban sustainable development policies. In this study, we investigated the trends and influencing factors of NPP in the BTH region from 2001 to 2020 from the perspective of the three spatial types (ecological space, production space, and living space), considering both natural and human factors. The results showed that: (1) From 2001 to 2020, the area of living space in the BTH region increased the fastest, by 7661.709 km² (49.76%), while both ecological space and production space areas decreased. (2) From 2001 to 2020, the overall NPP in the BTH region showed a fluctuating upward trend, with a significant decrease in NPP in the southeastern plains around urban centers. The average NPP and annual growth rates exhibited a pattern of ecological space > production space > living space. (3) Results based on the Geodetector and Generalized Additive Model showed that the factors influencing NPP changes varied greatly across the three spatial types. Specifically, human activities were the dominant factors in living spaces, while natural factors dominated in production and ecological spaces. The results of this study contribute to a deeper understanding of vegetation growth changes and the underlying mechanisms in the Jing-Jin-Ji Region.

Key words: net primary productivity, production-living-ecological space, Jing-Jin-Ji Region, spatiotemporal pattern