Increasing concentrations of atmospheric greenhouse gases (GHG) lead to irreversible consequences for the future of Earth. However, the general pattern of the impacts of ecological restoration on the three major GHGs at a global scale has not yet been analyzed.

Land use change and ecosystem degradation have caused massive anthropogenic emissions of greenhouse gases (GHG), such as carbon dioxide (CO₂), methane (CH₄) and nitrous oxide (N₂O), leading to irreversible consequences for the future of Earth. According to a new study by Wuhan Botanical Garden in “Nature communication”, forest, grassland and wetland restoration can enhance carbon sink, reduce the global warming potentials, and serve as strategies for mitigating GHG. This study is a meta-analysis of global dataset from 253 peer-reviewed articles. The results offer valuable insights for policymakers to select effective ecological restoration measures.

Forests, grasslands and wetlands are the three major ecosystems which are crucial for the global GHG budget, but there are multiple factors (restoration types, ways and age, etc.) affecting GHG. “Despite numerous studies investigating the effects of ecological restoration on the emission of individual or a few GHGs at the plot or regional level, the general pattern of the impacts of ecological restoration on the three major GHGs at a global scale has not yet been analyzed”, explains Professor ZHANG Kerong. In order to obtain a global overview, researchers analyzed data from 235 studies to quantify the impacts of ecological restoration on GHG emissions.

The team found that forest and grassland restoration significantly increased CH₄ uptake by 90% and 30.8% respectively, while, wetland restoration significantly enhanced CH₄ emission by 544.4%. Forest and grassland restoration showed no distinct impacts on N₂O emissions, while, wetland restoration significantly decreased N₂O emissions by 68.6%.

"This study highlights the significance of restoration age in regulating GHG emissions in restored ecosystems” says Dr. HE Tiehu. The net ecosystem CO₂ exchange (NEE) in wetlands was exponentially and negatively correlated with restoration age, and the switchover time from net CO₂ sources to net CO₂ sinks was estimated to be approximately four years. The NEE of the restored forests decreased with afforestation and reforestation age, and the estimated swithover time required from CO₂ sources to net sinks was approximately three-five years, and approximately six years for the clear-cutting sites and 13 years for the post-fire sites.

Taking together, the study suggested that forest, grassland and wetland restoration could serve as an effective strategy for mitigating GHG emissions and reducing global warming potentials.

This research was supported by the National Natural Science Foundation of China and Youth Innovation Promotion Association CAS.

Relationships of the response ratios (RRd) of CH₄ and N₂O fluxes, and the annual CO₂ fluxes with restoration age (Image by WBG)