De Wieden and De Weerribben (Netherlands)

The De Weerribben and De Wiede National Park in the Netherlands is home to the largest fen-peatland system in North-western Europe. For centuries, this biodiversity-rich landscape was shaped by a combination of human activities, especially peat cutting for fuel. As the profitability of peat cutting declined, the local economy shifted towards other activities such as reed cutting, which required careful water-level management and prevented natural succession of peatlands to woodlands. Reed cutting enhanced the growth of a diverse mosaic of open waters, transitional fens and reed beds providing natural habitats for bitterns, reed warblers, black terns, and rare dragonflies.

The intensification of agriculture in the areas surrounding the wetland led to increased drainage, lowering the (ground)water level and causing nutrient pollution in surface waters and atmospheric deposition of nitrogen. As a result, habitat quality decreased, leading to, amongst others, the deterioration of specific peatland vegetation types and wood encroachment.

Efforts to restore the unique and rare system of De Weerribben and De Wiede are carried out by Natuurmonumenten – a major conservation NGO which acts as co-manager of De Wieden. Additionally, the nature management organisation Staatsbosbeheer is implementing restoration measures in de Weerribben. One of the most representative examples of restoration is taking place is the Kiersche Wijde, where the former agricultural grasslands are being transformed into fen peatland meadows.

The first stage of the restoration process pursued the recovery of fen vegetation through sheep grazing on the grasslands and later frequent mowing of the vegetation to deplete soil nutrients (especially phosphorous) with the removed biomass. Nevertheless, vegetation growth was held back by excess nutrients and lowered water tables5.

In a second phase, efforts focused on raising the water table of the wetland in summer to prevent drawdowns in dry periods. Furthermore, grasslands were flooded periodically by pumping in nutrient-poor mineral-rich surface water, leading to periodic flooding episodes in autumn to flush out excess phosphorus. In addition, the excavation of new pits supported vegetation succession from open water to land. Also seeds from nearby intact fenland vegetation were introduced via hay to reintroduce fenland plant species.

Currently, the management of this site focuses on:
– Improving biodiversity through the creation and expansion of areas of open water and rare fen habitats
– Removing biomass to reduce the soil nutrient legacy of agricultural use and enhance peat-forming species.
– Control of invasive aquatic plants in the ditches and peat pits
– Monitoring the increase in carbon sequestration and storage levels under different management and restoration scenarios and events, as part of the Horizon REWET project.
– Testing, monitoring and adapting the management measures (adaptive management)
– Support to sustainable economic activities, such as traditional reed cutting, boating and low-impact tourism.
– Plans are underway to open a visitor center in Weerribben – the European Wetland Center.