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Recovery in soil carbon stock but reduction in carbon stabilization after 56-year forest restoration in degraded tropical lands

Zhang, Huiling, Deng, Qi, Hui, Dafeng, Wu, Jianping, Xiong, Xin, Zhao, Jianqi, Zhao, Mengdi, Chu, Guowei, Zhou, Guoyi, Zhang, Deqiang
Forest ecology and management 2019 v.441 pp. 1-8
Eucalyptus, afforestation, carbon, carbon dioxide, carbon sequestration, carbon sinks, forest restoration, secondary forests, soil, soil carbon, storage time, tropical forests, China
Afforestation is considered as an effective method for alleviating the rising of atmospheric carbon dioxide (CO2) concentration through the accumulation and long-term storage of carbon (C) in the vegetation and soil. However, it is still unknown whether soil C accumulation in the restored forests could eventually recover to the equivalent level of the undisturbed forests and much less is known about how afforestation will affect C stabilization. Here we conducted a field study in degraded tropical forests of south China. The aim was to evaluate the recovery of soil C stock following afforestation by comparing different C fractions in soils (0–10 cm and 10–20 cm) in two reforested forests [a restored secondary forest (RSF) and a managed Eucalyptus plantation (MEP)] to those in a bare land (BL) and a nearby undisturbed forest (UF). Results showed that after 56-year afforestation at the bare lands, C stocks in both soil layers were significantly increased with an increase greater in the RSF than the MEP, while C recalcitrant indices (RI) were reduced. Soil C stock in the RSF recovered to a similar level to the UF, but soil RI in the RSF was still lower than the UF particularly in the 10–20 cm layer. The calculated capacity of soil C sequestration with the product of soil C stock and its RI followed the order of UF > RSF > MEP > BL. Our results demonstrate that afforestation on degraded tropical lands could recover soil C stock within a few decades, but C stabilization would be reduced.