Environment: Rewetting fen peatlands does not restore original ecosystem

Restoring temperate fen peatlands via rewetting falls short of returning them to their original ecosystem states, according to a study published in Nature Communications. The findings have implications for ecological restoration policies.

Drainage of peatlands for agriculture, forestry or peat extraction releases large amounts of greenhouse gases, impairs local carbon sink capacity, and causes biodiversity losses. The 2021–2030 UN Decade of Ecosystem Restoration has set ambitious targets for restoring drained peatland via rewetting as a climate change mitigation tool. However, whether biodiversity and ecosystem functions, beyond the reduction of greenhouse gases, are effectively restored is unclear.

Jürgen Kreyling and colleagues investigated 563 fen peatlands in Europe, comparing formerly drained sites that were rewetted to nearby sites that were left relatively undisturbed. The authors collected field data on vegetation, hydrology, and geochemistry, and mapped land cover characteristics with satellite imagery. They report that the rewetted fens differ from the near-natural sites in terms of plant community and some ecosystem functions. They found that rewetted sites showed altered plant communities, more variable water tables, and lower organic matter content and higher bulk density of the peat. The authors also show that although some of the peatlands were rewetted decades before the study, the older rewetted sites are no more similar to the near-natural counterparts than those more recently rewetted.

Although these findings do not contradict previous reports on the climate change mitigation potential of peatland rewetting, the authors indicate that restoring drained peatlands does not restore the biodiversity or ecosystems found in existing intact peatlands quickly. They call for more research to enable a better understanding and management of rewetted fen peatlands.