Degradation reduces greenhouse gas emissions while weakening ecosystem carbon sequestration of Moso bamboo forests

Moso bamboo (Phyllostachys heterocycla cv. Pubescens) is well known for its high capacity to sequester atmospheric carbon, which has a unique role to play in combating global warming. Many Moso bamboo forests are gradually degrading due to rising labor costs and falling prices for bamboo timber. However, the mechanisms of carbon sequestration of Moso bamboo forest ecosystems in response to degradation are unclear. In this study, a space-for-time substitution approach was used to select Moso bamboo forest plots with the same origin and similar stand types, but different years of degradation, and four degradation sequences, continuous management (CK), 2 years of degradation (D-I), 6 years of degradation (D-II) and 10 years of degradation (D-III). A total of 16 survey sample plots were established based on the local management history files. After a 12-month monitoring, the response characteristics of soil greenhouse gases (GHG) emissions, vegetation, and soil organic carbon sequestration in different degradation sequences were evaluated to reveal the differences in the ecosystem carbon sequestration. The results indicated that under D-I, D-II, and D-III, the global warming potential (GWP) of soil GHG emissions decreased by 10.84 %, 17.75 %, and 31.02 %, while soil organic carbon (SOC) sequestration increased by 2.82 %, 18.11 %, and 4.68 %, and vegetation carbon sequestration decreased by 17.30 %, 33.49 %, and 44.76 %, respectively. In conclusion, compared to CK, the ecosystem carbon sequestration was reduced by 13.79 %, 22.42 %, and 30.31 %, respectively. This suggests that degradation reduces soil GHG emissions but weakens the ecosystem carbon sequestration capability. Therefore, in the background of global warming and the strategic goal of carbon neutrality, restorative management of degraded Moso bamboo forests is critically needed to improve the carbon sequestration potential of the ecosystem.