A degraded bog returns to life

The area covered by fens and bogs in Switzerland has diminished by 80 % since 1900. Although fens and raised bogs are now protected, habitat quality continues to decline. But targeted restoration projects can reverse the trend.

Machines at work for nature: a digger is building dams and excavating ponds to re-wet the bog.
Photo © Yvan Matthey

The Yellow-spotted Whiteface, an endangered species in Switzerland, is one of the target species for ecological restoration in the Marais de la Châtagne.
Photo © Sébastien Tschanz

The valley of La Brévine in the canton of Neuchâtel is home to bog lands of national importance. They are made up of several distinct areas that are catalogued in the inventory of raised bogs, including the “Marais de la Châtagne”. Peat was extracted here for horticulture up until 1995. After peat extraction was shut down, the bog was left alone. But extraction had heavily modified the raised bog so that it dried out over the years and was colonised by willow, resulting in a huge loss of the typical flora and fauna of a raised bog. In 2020, Pro Natura Neuchâtel purchased about 5 hectares of land in the raised bog with the aim of restoring the Marais de la Châtagne. The plan was to remove scrub, raise the water table and create pools. At this point, Pro Natura contacted the Swiss Ornithological Institute with a request for support.

As part of a new multi-year project (see box), the Swiss Ornithological Institute contributed expertise as well as funds to the restoration of the Marais de le Châtagne. We made a list of bird species that could potentially benefit from the restoration and assessed the measures in view of their effectiveness for bird conservation. Continued monitoring and impact assessment following the restoration ensure that the management of the area can be adjusted if necessary. The Swiss Ornithological Institute monitors the impact of mea-sures on birds, especially on target species such as Tree Pipit and Willow Warbler. Working with the Cantonal Office for Fauna, Forest and Nature, we also monitor the dragonfly population, as dragonflies are the project’s main target species group. We know from earlier raised bog restorations in the region that threatened and extremely rare species of dragonfly such as Yellow-spotted Whiteface (Leucorrhinia pectoralis) and Dark Whiteface (Leucorrhinia albifrons) show a quick and positive response to restorations. Our hope and aim is therefore to see the newly created pools in the Marais de la Châtagne being swiftly colonised.

The restoration work was carried out in November 2021. All in all, we hope that a species- rich bird community will benefit from the enhanced habitat, not only in the breeding season but during migration as well. As re-wetting the raised bog and fostering the formation of a mosaic habitat requires regular, site-adapted management, the Swiss Ornithological Institute and Pro Natura Neuchâtel have agreed to continue their cooperation on this site in the long term.