Story | 07/19/2023 09:09:45 | 4 min Read time

Methane hampers peatland restoration

Susanna Gygnel

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When water is returned to its natural elevation in the peatland, methane begins to form. Therefore, restoring peatlands is not a simple matter from a climate perspective. In the long term, however, the climate will benefit. Restoration also increases biodiversity.

More than half of Finland's peatlands, about 6 million hectares, have been drained for forests, farmlands and peat production. 

Drainage is not evenly distributed, with 80-90% of peatlands in southern Finland being drained. The majority of natural peatlands are located in Lapland, while in the southernmost part of Finland, only small isolated bogs remain. 

"As a result of drainage, more than half of the peatland habitats have become endangered and many flora and fauna species have become endangered with them", says Anna Laine-Petäjäkangas from the Geological Survey of Finland.

What is peatland restoration? (FI)

In order to protect and increase the biodiversity in peatlands, efforts have been made to restore drained peatlands. In southern Finland in particular, conservation measures alone are no longer sufficient. 

Drained bogs are restored by harvesting or removing trees from the bog and by restoring water conditions to the bogs by either filling or damming ditches.

What are the problems associated with restoring peatlands?

Restoring drained peatlands is almost always good for the climate, as the carbon stored in the peat layer is gradually released from the drained peatland into the atmosphere. 

"Restoring peatlands involves blocking ditches and raising the water level, which reduces peat decomposition and carbon emissions. In that sense, restoration is a climate initiative".

However, another greenhouse gas, methane, poses a problem. In wet ecosystems, such as peatlands, methane emissions occur when peat below the water surface decomposes under anoxic conditions. 

When the water level in the peatland is restored to its natural level, methane emissions from the peatland are also restarted. Therefore, restoring a peatland is not necessarily good for the climate in the short term.

Methane emissions are highest in wet and lush wetlands, i.e. where the boot does not fit. The methane escape from dandelions and sphagnum mosses is much lower. 

Despite being a powerful greenhouse gas, methane decomposes much faster in the atmosphere than carbon dioxide. The climate challenge will also level off in the long term as the peatland begins to absorb carbon dioxide, offsetting methane emissions. 

Long-term impacts of peatland restoration

According to Laine-Petäjäkangas, peatlands that are wasteland for wood production have also been drained. From a profit-seeking perspective, it is therefore preferable for the forest owner to restore the low-yielding defective plot rather than the productive one.

While restoring drained peatlands is not a quick fix for climate change, it will quickly bring relief to the world's biodiversity crisis. Plant species and habitats usually recover well in restored forest sites. Changes start to show in as little as 5-10 years. 

The most important peatland restoration measure is the ditch blocking (FI)

Climate change will bring challenges, and one way to fight them is to restore peatlands. Global warming will accelerate the decomposition of peat, which means that in the future the climate emissions from drained peatlands may be even higher than today. 

"In addition, forest fires occur more frequently as the dry season lasts longer. If a dried peat layer catches fire, extinguishing would be very challenging and the damage can be extensive. "The wet, open peatland forms a natural boundary to the fire."

When considering peatland restoration, think about your objectives

A forest owner planning to restore a peatland can weigh up whether he or she wants to focus on biodiversity or whether climate issues are more important – both are environmentally valuable objectives.

Biodiversity can be promoted most effectively in more open and boggy terrain, where water is returned to the peatland in abundance. If climate benefits are to be achieved, restoration should try to limit the amount of surface water in the peatland.

"Slightly drier peatland is better for the climate."

It has also been found that natural peatlands emit less methane into the atmosphere if they have a dense blanket of grass moss growing on their surface. 

The effects of transplantation are being studied in a research project by the University of Eastern Finland and the Finnish League for Nature Conservation, and the results have been promising.

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