Schuster Lukas, Taillardat Pierre, Macreadie Peter I, Malerba Martino E
School of Life and Environmental Sciences, Deakin University VIC 3125, Australia.
NUS Environmental Research Institute, National University of Singapore, Singapore 117411, Singapore.
Sci Total Environ. 2024 Apr 20;922:171218. doi: 10.1016/j.scitotenv.2024.171218. Epub 2024 Feb 27.
Freshwater wetlands have a disproportionately large influence on the global carbon cycle, with the potential to serve as long-term carbon sinks. Many of the world's freshwater wetlands have been destroyed or degraded, thereby affecting carbon-sink capacity. Ecological restoration of degraded wetlands is thus becoming an increasingly sought-after natural climate solution. Yet the time required to revert a degraded wetland from a carbon source to sink remains largely unknown. Moreover, increased methane (CH) and nitrous oxide (NO) emissions might complicate the climate benefit that wetland restoration may represent. We conducted a global meta-analysis to evaluate the benefits of wetland restoration in terms of net ecosystem carbon and greenhouse gas balance. Most studies (76 %) investigated the benefits of wetland restoration in peatlands (bogs, fens, and peat swamps) in the northern hemisphere, whereas the effects of restoration in non-peat wetlands (freshwater marshes, non-peat swamps, and riparian wetlands) remain largely unexplored. Despite higher CH emissions, most restored (77 %) and all natural peatlands were net carbon sinks, whereas most degraded peatlands (69 %) were carbon sources. Conversely, CH emissions from non-peat wetlands were similar across degraded, restored, and natural non-peat wetlands. When considering the radiative forcings and atmospheric lifetimes of the different greenhouse gases, the average time for restored wetlands to have a net cooling effect on the climate after restoration is 525 years for peatlands and 141 years for non-peat wetlands. The radiative benefit of wetland restoration does, therefore, not meet the timeframe set by the Paris Agreement to limit global warming by 2100. The conservation and protection of natural freshwater wetlands should be prioritised over wetland restoration as those ecosystems already play a key role in climate change mitigation.
淡水湿地对全球碳循环有着极大的影响，有可能成为长期碳汇。世界上许多淡水湿地已遭到破坏或退化，从而影响了碳汇能力。因此，退化湿地的生态恢复正日益成为备受关注的自然气候解决方案。然而，将退化湿地从碳源恢复为碳汇所需的时间仍 largely 未知。此外，甲烷（CH）和一氧化二氮（NO）排放的增加可能会使湿地恢复所带来的气候效益变得复杂。我们进行了一项全球荟萃分析，以评估湿地恢复在净生态系统碳和温室气体平衡方面的效益。大多数研究（76%）调查了北半球泥炭地（沼泽、泥炭沼泽和泥炭藓沼泽）湿地恢复的效益，而非泥炭湿地（淡水沼泽、非泥炭沼泽和河岸湿地）恢复的效果仍 largely 未被探索。尽管 CH 排放较高，但大多数恢复的（77%）和所有天然泥炭地都是净碳汇，而大多数退化泥炭地（69%）是碳源。相反，非泥炭湿地在退化、恢复和天然非泥炭湿地中的 CH 排放相似。在考虑不同温室气体的辐射强迫和大气寿命时，恢复后的湿地对气候产生净降温效应后的平均时间，泥炭地为 525 年，非泥炭湿地为 141 年。因此，湿地恢复的辐射效益未达到《巴黎协定》设定的到 2100 年限制全球变暖的时间框架。应优先保护和养护天然淡水湿地，而非进行湿地恢复，因为这些生态系统已在缓解气候变化方面发挥着关键作用。
