Rewetted fen peatlands - novel and essential for climate protection

Peatlands store twice as much carbon as all the biomass of the World’s forests. Vast areas of peatland have been drained and turned into CO2 sources. Their rewetting is essential to reduce CO2 emissions. But how exactly do the rewetted peatlands look like, do they resemble again the natural state?

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As a team of peatland scientists from Greifswald and Rostock universities in N Germany, we are situated in a region, where already 10% of the drained peatlands have been rewetted (in total 33,000 ha). With this treasure of rewetted landscapes infront of us, and knowing about the growing need for large-scale peatland rewetting and for better understanding of these ecosystems, we decided to bring together knowledge from temperate fen peatland rewetting across Central Europe.   

We used our network of peatland scientists and practitioners and especially the contacts of the Greifswald Mire Centre in the UK, the Netherlands, Belgium, Germany, Poland and Belarus to collate data from 320 rewetted and  243 undrained, near-natural sites to compare them across different aspects. Many contributors were able to process and provide their data during the "lockdown phases" in 2020. Thus, the Corona pandemic turned out as an unexpected support of our endeavour. Many people involved in peatland rewetting were eager to bring in their knowledge, largely unnoticed by the scientific community so far.

With our study, we look at biodiversity and ecosystem functions of rewetted peatlands. One ecosystem function that is crucial for humanity is very well studied: Rewetting drained peatlands strongly reduces or stops CO2 emissions. Looking beyond carbon, our results imply that rewetting of drained fen peatlands induces the establishment of tall, graminoid wetland plants (helophytisation) and long-lasting differences to pre-drainage biodiversity (vegetation), ecosystem functioning (geochemistry, hydrology), and land cover characteristics (spectral temporal metrics). Understanding and management schemes cannot be transferred from natural systems. Instead, an interdisciplinary, process-based understanding of the rewetted systems is urgently needed to prioritize, plan and implement restoration measures and to design their sustainable management.

Rewetted fen peatland in NE-Germany (T. Dahms)

The UN Decade of Ecosystem Restoration starting this year is the critical period for achieving our commitments of the Paris Agreement on peat soils and for peatland science. Therefore, we call for a concerted action to assemble a coordinated set of data on ecological functioning, including relevant meta information, across a wide range of rewetted peatlands. The Paris Agreement entails the rewetting of 500,000 km2 of drained peatlands worldwide until 2050-2070. A better understanding of the resulting locally novel ecosystems is required to improve planning and implementation of peatland rewetting and subsequent management.

Franziska Tanneberger

Senior researcher & Director Greifswald Mire Centre, Greifswald University