Shang Rong, Chen Jing M, Xu Mingzhu, Lin Xudong, Li Peng, Yu Guirui, He Nianpeng, Xu Li, Gong Peng, Liu Liangyun, Liu Han, Jiao Wenzhe
Key Laboratory for Humid Subtropical Eco-Geographical Processes of the Ministry of Education, School of Geographical Sciences, Fujian Normal University, Fuzhou 350117, China.
Department of Geography and Planning, University of Toronto, Toronto, Ontario M5S 3G3, Canada.
Innovation (Camb). 2023 Sep 16;4(6):100515. doi: 10.1016/j.xinn.2023.100515. eCollection 2023 Nov 13.
Forests are chiefly responsible for the terrestrial carbon sink that greatly reduces the buildup of CO concentrations in the atmosphere and alleviates climate change. Current predictions of terrestrial carbon sinks in the future have so far ignored the variation of forest carbon uptake with forest age. Here, we predict the role of China's current forest age in future carbon sink capacity by generating a high-resolution (30 m) forest age map in 2019 over China's landmass using satellite and forest inventory data and deriving forest growth curves using measurements of forest biomass and age in 3,121 plots. As China's forests currently have large proportions of young and middle-age stands, we project that China's forests will maintain high growth rates for about 15 years. However, as the forests grow older, their net primary productivity will decline by 5.0% ± 1.4% in 2050, 8.4% ± 1.6% in 2060, and 16.6% ± 2.8% in 2100, indicating weakened carbon sinks in the near future. The weakening of forest carbon sinks can be potentially mitigated by optimizing forest age structure through selective logging and implementing new or improved afforestation. This finding is important not only for the global carbon cycle and climate projections but also for developing forest management strategies to enhance land sinks by alleviating the age effect.
森林是陆地碳汇的主要贡献者，它极大地减少了大气中二氧化碳浓度的积累，缓解了气候变化。目前对未来陆地碳汇的预测迄今忽略了森林碳吸收量随森林年龄的变化。在此，我们通过利用卫星和森林清查数据生成2019年中国陆地高分辨率（30米）森林年龄地图，并使用3121个样地的森林生物量和年龄测量数据推导森林生长曲线，来预测中国当前森林年龄在未来碳汇能力中的作用。由于中国森林目前年轻和中年林分占比很大，我们预计中国森林将在约15年内保持高生长率。然而，随着森林年龄增长，到2050年其净初级生产力将下降5.0%±1.4%，到2060年下降8.4%±1.6%，到2100年下降16.6%±2.8%，这表明近期碳汇将减弱。通过择伐优化森林年龄结构以及实施新的或改进的造林措施，有可能缓解森林碳汇的减弱。这一发现不仅对全球碳循环和气候预测很重要，而且对制定森林管理策略以通过减轻年龄效应增强陆地碳汇也很重要。
