The dynamics of carbon accumulation in Eucalyptus and Acacia plantations in the Pearl River delta region

Abstract

Key message: Plantation type and age strongly influence the quantity of carbon stored in forest ecosystems. The marked increase in total ecosystem carbon stock achieved over time by theEucalyptusandAcaciaplantations has confirmed that the afforestation of degraded soils can contribute positively to carbon sequestration. Context: Reforestation has been widely conducted to restore and protect the eroded red soil in south China in recent decades. The question as to whether the content of soil organic carbon (SOC) can be boosted by establishing plantations of fast-growing tree species remains unresolved. Aims: We addressed whether the afforestation of degraded soils can contribute positively to carbon sequestration, and whether the accumulation of SOC is more effective under a nitrogen fixing species such as Acacia than under Eucalyptus. Methods: Here, a study was undertaken to measure the quantity of total ecosystem carbon (TEC) accumulated by plantations of both Eucalyptus and Acacia spp. in the Pearl River Delta region of southern China. Results: The quantity of TEC increased significantly with stand age in both plantation types (P < 0.05). The largest single component of TEC was SOC, with stand age having a considerable effect on both SOC and overall biomass. The accumulation of SOC in the top 100 cm of the soil profile was higher under Acacia than under Eucalyptus (P < 0.05). Conclusion: In terms of carbon sequestration, the afforestation of Eucalyptus and Acacia represent an effective forest management practice. The accumulation of SOC is more effective under Acacia than under Eucalyptus.