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MERLIN restoration case studies: peatlands and wetlands

June 8, 2022
The seven peatland and wetland sites in the MERLIN project: (1) Nørreådalen ved Kvorning, Denmark; (3) Beaver reintroduction, Sweden; (5) Kampinos wetlands, Poland; (6) Karstic peatland, Bosnia and Herzegovina; (12) Lima basin, Portugal; (14) Oulujoki-Iijoki catchments, Finland; (17) Forth catchment, Scotland.

The MERLIN project focuses on 17 freshwater restoration case studies located across Europe.

These diverse sites and projects – including large rivers, small streams, peatlands and wetlands – offer researchers the opportunity to explore best-practice approaches for restoration in contemporary landscapes. The project will document how the impact of these projects contributes to the targets of the EU Green Deal.

Moreover, MERLIN is investing more than €10 million in these restoration projects to help upscale their management through the use of nature-based solutions. It is intended that the progress made in bringing freshwaters back to life at these sites will help strengthen arguments for mainstreaming freshwater restoration across the continent.

This is the first of three articles introducing the 17 restoration case studies. This week, we focus on the seven peatland and wetland sites.

Nørreådalen ved Kvorning peatlands. Image: Annette Baattrup-Pedersen

Nørreådalen ved Kvorning, Denmark

Rewetting peatlands for carbon storage, water quality and biodiversity

A 430 ha area of lowland arable fields in Northern Denmark will be ‘rewetted’ through the restoration of natural hydrological processes. Measures to restore the site’s peatlands include closing agricultural drainage ditches and re-meandering streams.

The plan is for the water level of the site to rise, which will reduce the loss of organic carbon stored over millennia and reinstate the conditions for its natural formation. In turn, it is intended that peatland restoration will reduce carbon dioxide and nitrous oxide emissions from the soil, and improve carbon sequestration from the atmosphere. This will improve the site’s capacity to act as a greenhouse gas sink.

State-of-the-art filter technologies will also be used to reduce phosphorous pollution into surrounding streams. Cleaner water and better habitat quality resulting from restoration are intended to boost biodiversity at the site.

“Rewetting in combination with other restoration measures is proposed as a valid strategy to restore the unique biodiversity of peatlands and the recreation of the carbon and nutrient sink function,” say restoration managers from the Danish Nature Agency.

Find out more.

A beaver engineered landscape in Torringen, Sweden. Image: MERLIN

Beaver reintroduction, Sweden

Natural ecosystem engineering to boost biodiversity, reduce flooding and mitigate drought

Beavers are recolonising forest landscapes in river catchments across Sweden following decades of decline. Beavers are natural parts of these ecosystems, but their numbers have been reduced in many areas due to human activities and over-hunting. Reintroductions of beavers from Norway took place in Sweden in the 1920s and 30s, and their populations have gradually spread since.

By building dams, beavers act as ‘ecosystem engineers’ which can benefit the wider landscape. By raising water levels and slowing river flows, their dams can help mitigate drought and reduce flooding. Studies also suggest that their activities can benefit the wider ecosystem by creating nursery areas for spawning fish and new habitats for plants and insects.

Beaver reintroduction work in MERLIN builds on existing projects across Sweden. These projects frame the animals as active participants in the ecological restoration of river catchments degraded by agriculture and forestry: a truly nature-based solution.

“The restoration performed by beavers could catalyse landscape transformation due to the ecosystem engineering scale of their activities,” say case study managers from Swedish University of Agricultural Sciences.

Find out more.

Kampinos wetlands, Poland. Image: M.Szajowski and A.Andrzejewska

Kampinos wetlands, Poland

Restoring wetlands for biodiversity, flood buffering and carbon storage

Two hundred and fifty years of drainage for agriculture have caused the Kampinos wetlands in central Poland to shrink and dry out, leading to the loss of important biodiversity. Restoration at the site seeks to ‘rewet’ over 6000 ha of the wetlands by constructing small dams and dykes which slow the flow of water from the site and raise the groundwater to pre-drainage levels.

The Kampinos wetlands are a unique habitat. Located close to the city of Warsaw, they are protected within a national park and UNESCO Biosphere Reserve due to their habitats for rare plants, birds, mammals, fish, amphibians and insects. Restoration work at the site is intended both to boost biodiversity and improve wetland capacity to buffer floodwaters and store carbon.

“This case study is a diverse, large-scale wetland protection effort which is implemented in the neighbourhood of highly urbanised area and area of large human pressure,” say site managers from the Kampinoski Park Narodowy. “Restoration is expected to enrich the biodiversity of meadows, ditches, rivers and ponds.”

Find out more.

Karstic peatlands, Bosnia. Image: F.Techene

Karstic peatland, Bosnia and Herzegovina

Restoring sustainable water systems in a unique peatland landscape

The karstic peatlands in Bosnia and Herzegovina are a hotspot for biodiversity and a vital landscape for carbon sequestration. Their unique formation of peatland on karstic limestone bedrock is extremely rare, and is increasingly threatened by water demands for irrigation and hydropower. This, coupled with land reclamation for agriculture, significantly threatens the karstic peatland ecosystems of the region.

The complex water flows – through underground rivers, sinkholes and springs – across karstic peatlands makes restoration management challenging. Their restoration requires close collaboration with agriculture and hydropower industries to shift their practices towards sustainable water usage, which will allow more natural water systems to return to the landscape.

“The Dinaric karst fields are biodiversity hotspots – especially for endemic species – as well as the most prominent natural carbon sequestration ecosystems in Europe,” say environmental managers from WWF Adria. “The Dinaric karst fields have played a crucial role for climate regulation and mitigation of climate change. Water allocations and land reclamation have brought the karst field ecosystems to the brink of disappearance.”

Find out more.

Artificial fishing barriers on the Lima River, Portugal. Image: MERLIN

Lima basin, Portugal

Restoring Iberian river corridor wetlands and forests

Restoration of wetland and floodplain forest is planned along the River Lima in north-west Portugal. Floodplains along the Lima valley have been drained, channelised and altered for decades to allow urban and agricultural development. In addition, the river is regulated by two large hydropower dams.

Restoration of the Lima floodplains seeks to re-establish wooded wetland ecosystems, as part of a wider LIFE Fluvial project to improve ‘river corridor’ habitats across the north-west Iberian Peninsula. This work highlights the value of river corridors as unique connections between freshwater and terrestrial habitats. Restoration measures in the catchment will include livestock grazing management, invasive species control (particularly of Eucalyptus plantations and Acacia species) and native tree planting. Fish passes will be installed on the hydropower dams.

“The floodplain forest restoration intends to develop and demonstrate an ecological restoration approach for fluvial floodplains transferable to lowlands across the biogeographic region of the north-west Iberian Peninsula,” say project managers from the University of Lisbon.

Find out more.

Restoration of former peatland extraction site in the Oulujoki-Iijoki catchments, Finland. Image: Mirkka Visuri

Oulujoki-Iijoki catchments, Finland

Participatory watershed visions for restoring abandoned peatlands

The peatlands in the Oulujoki-Iijoki river basin region in Northern Finland have been altered and drained for forestry, agriculture and peat extraction for decades. This has caused the loss of peatland ecosystems, alterations to stream habitats, and deterioration in water quality due to nutrient, carbon and dissolved metal pollution.

Environmental management across the basin seeks to find sustainable land uses for extracted peatlands by restoring their ecosystem functions through ‘rewetting’. The plan is that peatland restoration will boost biodiversity and help naturally purify water in the basin, improving water quality. It is also intended that restoration will help buffer floodwaters, and improve carbon capture and storage in the basin.

Restoration in the Oulujoki-Iijoki basin is being guided by ‘watershed visions’ which involve local communities, experts, NGOs and government in participatory management, and offer funding for local restoration projects.

“These watershed vision projects provide innovative applications for restoration projects and governance at different scales,” say restoration managers from the Finnish Environment Institute, SYKE. “The idea behind these projects is that there is an advisory board, consisting of local people, NGOs and municipalities, which sets up collective targets for the future and determines ways how to reach them.”

Find out more.

Blocked ditch at Flanders Moss in the Forth Catchment, Scotland. Image: Lorne Gill/SNH

Forth catchment, Scotland

Wetland and peatland restoration for ecological, economic and social benefits

Peatland restoration plays a key role in Scotland’s ‘green recovery’. Restoration can help deliver the transition to net-zero by supporting the rural economy through the creation and development of land-based jobs and skills across Scotland.

The restoration effort in the River Forth catchment in eastern Scotland aims to restore several peat bogs and their carbon stores, helping mitigate climate change, reduce carbon emissions and tackle habitat loss. The plan for this case study is to remove conifer plantations, block drainage ditches and rewet degraded peat bogs for improvement of carbon sequestration, water retention capacity and biodiversity.

“This project will also provide us with important lessons to rapidly upscale the most valuable solutions in time to meet our net zero and biodiversity targets,” says the NatureScot lead for the Forth catchment.

Find out more.


This article is supported by the MERLIN project.

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