Zhang X M, Brandt M, Yue Y M, Tong X W, Wang K L, Fensholt R
Guangxi Key Laboratory of Karst Ecological Processes and Services Institute of Subtropical Agriculture Chinese Academy of Sciences Changsha China.
Huanjiang Observation and Research Station for Karst Ecosystem Chinese Academy of Sciences Huanjiang China.
Earths Future. 2022 Dec;10(12):e2022EF002674. doi: 10.1029/2022EF002674. Epub 2022 Dec 1.
Afforestation and land use changes that sequester carbon from the atmosphere in the form of woody biomass have turned southern China into one of the largest carbon sinks globally, which contributes to mitigating climate change. However, forest growth saturation and available land that can be forested limit the longevity of this carbon sink, and while a plethora of studies have quantified vegetation changes over the last decades, the remaining carbon sink potential of this area is currently unknown. Here, we train a model with multiple predictors characterizing the heterogeneous landscapes of southern China and predict the biomass carbon carrying capacity of the region for 2002-2017. We compare observed and predicted biomass carbon density and find that during about two decades of afforestation, 2.34 PgC have been sequestered between 2002 and 2017, and a total of 5.32 Pg carbon can potentially still be sequestrated. This means that the region has reached 73% of its aboveground biomass carbon carrying capacity in 2017, which is 12% more than in 2002, equal to a decrease of 0.77% per year. We identify potential afforestation areas that can still sequester 2.39 PgC, while old and new forests have reached 87% of their potential with 1.85 PgC remaining. Our work locates areas where vegetation has not yet reached its full potential but also shows that afforestation is not a long-term solution for climate change mitigation.
植树造林和土地利用变化以木质生物量的形式从大气中固存碳，这使得中国南方成为全球最大的碳汇之一，有助于缓解气候变化。然而，森林生长饱和以及可用于造林的土地有限，限制了这个碳汇的持久性。虽然大量研究已经量化了过去几十年的植被变化，但该地区剩余的碳汇潜力目前尚不清楚。在此，我们使用多个表征中国南方异质景观的预测变量训练一个模型，并预测该地区2002 - 2017年的生物量碳承载能力。我们比较了观测和预测的生物量碳密度，发现经过约二十年的造林，2002年至2017年期间固存了2.34PgC的碳，并且总共仍有5.32Pg碳有可能被固存。这意味着该地区在2017年已达到其地上生物量碳承载能力的73%，比2002年增加了12%，相当于每年下降0.77%。我们确定了仍可固存2.39PgC的潜在造林区域，而新旧森林已达到其潜力的87%，仍有1.85PgC的碳未被固存。我们的研究确定了植被尚未充分发挥潜力的区域，但也表明造林并非缓解气候变化的长期解决方案。
