Sustainable growth of China’s forest biomass carbon storage since 2002: Facing threats and loss risks

Forest biomass carbon storage (BC) plays a critical role in mitigating climate change. However, the spatiotemporal patterns and stability of BC growth in China remain unclear. Using the latest BC maps (2002–2021) and multi-source remote sensing data, we analyzed the spatiotemporal dynamics of BC and applied resilience indicators to reliably assess its stability. Our results show that while China’s long-term BC has continued to increase, the risk of BC losses has also intensified, particularly in old forests (>70 years), where approximately half exhibit a declining trend. Moreover, BC dynamics do not consistently align with resilience changes. About 53.4 % of forests display weakening resilience, directly reducing BC accumulation rates by 23.1 % and amplifying interannual variability. Alarmingly, 10.4 % of forests (BC-, resilience-), predominantly high-BC-density forests (mean: 28.3 tC/ha), face an extremely high risk of carbon loss (carbon emissions: -118 Tg C). We further found that the accelerating effect of resilience weakening on BC losses significantly outweighs the promoting effect of resilience enhancement on BC accumulation (-17.79 ± 4.72 Mg/ha vs. 11.47 ± 3.42 Mg/ha). Our study highlights that China’s BC growth is characterized by unstable components and faces substantial loss risks. In future efforts to enhance forest carbon sinks, greater attention should be paid to changes in forest resilience to improve the stability of biomass carbon sinks and achieve sustainable, long-term carbon sequestration.