In Central Europe, peatland forests are regarded as the "bad boy" of climate policy, Professor Annamari Laurén (Annamari Laurén) says in an interview with Audiomedia.

• Restoring peat bogs may increase climate emissions for another 100 years
• Peat bog restoration is named as one of the means of implementing the European Union's Nature Restoration Regulation.
• If tree growth is taken into account, drained peatland forests act as carbon sinks
• Restoring productive forest land is not cost-effective, though it may be necessary for conserving biodiversity
• Trees grow better on peatlands when the water level in them is fairly high. This also reduces carbon emissions from the soil

Annamari Laurén, Professor of Peatland Forestry at the University of Helsinki, believes that restoring peatlands will not solve the problem of global warming.

"When it comes to climate targets, people expect too much from peatland restoration. To begin with, restoration will produce a warming effect for no less than a hundred years, and only then will it start to deliver the expected results," Professor Laurén notes.

Most commercially usable peatland forests have already been drained at some point. Peat bog restoration involves blocking or filling in drainage ditches. As a result, more water will be retained in the area concerned, peatland vegetation will return and, either naturally or through felling, the number of trees will decrease. Blocking drainage ditches has been designated as one of the ways of implementing the European Union's Nature Restoration Regulation.

All European Union matters relating to forests are especially important to Finland, as Europe's most forest-rich country. Forests cover more than 75% of Finland's land area.

Peat bogs as the "bad boys"

Laurén says she is the world's only university professor in the field of peatland forestry. In her view, the notion of peatlands as "bad boys" has largely been shaped by peatland researchers in Germany and the Netherlands, who have little experience of forested peatlands.

"In Central Europe and Great Britain, the drainage of peatlands for agriculture began as early as the 15th century, and there are few peatland forests there. Forested peatland areas such as ours here in Finland seem unnatural from their point of view." The professor points out that, to a large extent, the drainage of peatland forests in Finland has been a success story.

"At present, peatland forests account for a quarter of total forest income," Laurén explains. "The Finns are in a unique situation with regard to peatland forests, because in Sweden and Norway the share of such forests in the total forest area is small enough that restoring them would not have as great an impact on society as it would in Finland. Finland has a unique combination of peatlands and forests."

In Finland, peatland forests account for a quarter of total income earned from forests

Drainage improves the growth of peatland forests

Professor Laurén believes that those taking part in debates about forests should try to understand history rather than simply blaming earlier generations for draining peatlands. "At the beginning of the 20th century, Finland's forests were in a catastrophic state. Since peatlands cover one third of the land area, people began to see peatland forests as a resource whose growth ought to be encouraged. If peatlands made up only one tenth of Finland's land area, we could afford to exclude them from forestry," she explains.

Productive forest land is a carbon store

Annamari Laurén says that productive forest land should not be restored, because it is important for timber production and acts as a carbon sink; at the same time, she does not want to abandon peatland restoration altogether.

"If forestry needs are taken into account when planning restoration, we will not go wrong. Peat bogs where forestry cannot thrive can be restored." Professor Laurén stresses that the carbon balance of peatland forests must be viewed as a whole, covering both the soil and the forest. "Drained peatlands act as carbon sinks if the process of tree growth is taken into account. If peatlands are drained, carbon stocks in the soil decrease. If we want to cool the climate in less than a hundred years, we must keep peatlands forested and growing, and also raise the groundwater level in peatland forests used for timber production."

In Laurén's view, sphagnum peatlands are suitable for restoration, because they have high water retention.

"Since they are wet in any case, I do not think they will deliver significant carbon credits. Old spruce mire stands with environmental and biodiversity value can be restored by helping them to retain water. If too much water is retained in spruce mires, the trees die. Rewetting has to be carried out very skilfully; it is an easy task to get wrong."

Nature does not listen to politicians

Professor Laurén points out that nature does not adapt itself to policy targets.

"Nature follows its own laws, and we have to know them. The ecosystems of drained forests have already changed in many respects, so restoration can be a misleading term. A more neutral term for peatland forests is the restoration of the water regime (rewetting)," Professor Laurén stresses.

In Laurén's view, some types of peatland forest — for example, mires with thin surface layers where grasses, woody plants, bilberries and/or cowberries grow — are excellently suited to afforestation. "They give the same income per hectare as the corresponding mineral soils," says Laurén, who stresses that it is necessary to determine the biodiversity benefits achieved by restoring particular peatland forests. "If biodiversity constraints are identified, they can be remedied by restoring forests."

The importance of water management in peatland forests

Professor Laurén also turns to the importance of managing the hydrology of peatland forests. According to the latest research, trees on peatlands will grow best when the water level in them is sufficiently high. This also reduces carbon emissions from the soil.

"This means that drainage ditches can be blocked or allowed to recover gradually in nature. Compared with mineral soils, far more tools can be used on peatlands to regulate forest growth and prepare for drought."

One of these tools is the improvement of peatland forests with wood ash. According to figures from Tapio, an organisation of forest experts, doubling the area currently treated would make it possible to obtain up to one million cubic metres of additional wood growth. After soil improvement, forests sequester more carbon than is generated during the production and use of the soil improvement agents.

"By using ash, we can maintain good growing capacity on open peatland bogs for as long as 40-70 years. Applying ash slightly increases soil emissions, which can be offset by raising the groundwater level. A peat bog of this kind will provide a balanced growing site for trees. That is why I would like peatlands to continue to be included in forestry," says Professor Annamari Laurén.