Ecosystem engineering and global changes are increasingly enhancing China’s terrestrial carbon sinks

Ecosystem engineering-driven land-use change (LUCC) and global changes (climate change, elevated CO₂, and nitrogen deposition) profoundly affect net ecosystem productivity (NEP), yet their temporal dynamics remain unclear. Using a process-based model, we evaluated their effects on NEP in China’s ecosystem engineering zones from 2001 to 2021. Results showed an average NEP of 256 Tg C yr^-1, increasing at a rate of 11.3 Tg C yr^-2, primarily driven by afforestation (effect increasing at 2.9 Tg C yr^-2) and elevated CO₂ (effect increasing at 5.6 Tg C yr^-2)—higher than that of climate change (0.4 Tg C yr^–2). LUCC-global change interactions strengthened, contributing 27 % (2001–2010) to 32.1 % (2011–2021) of the LUCC effect, primarily due to increasing CO₂ and shifting precipitation. Furthermore, we identified optimal climatic spaces (precipitation: 750–2600 mm, temperature: 10–25 °C) that enhanced interactions. Restricting afforestation to these areas could enhance NEP by 65 %. Our findings highlight afforestation’s persistent carbon sink potential under global change, providing key insights for optimizing sustainable land management.