Re-establishing freshwater wetlands in Denmark

A national programme for the restoration of freshwater wetlands in Denmark was initiated in 1998. The purpose was to reduce nitrogen load to down-stream recipients and to enhance nature values in restored areas. In August 2005, 3060 ha of land was restored and 3769 ha of land approved for restoration. A monitoring programme for surveying the effects of the restoration of the wetlands has been set up. The programme includes basic data on land use and surveys of environmental effects and natural values.Basic data on land use in restored wetlands has shown that areas were dominated by agriculture (42%) and meadow-land (39%) prior to the re-establishment. Areas possessing plant communities with a high conservation value had a very restricted extension prior to project implementations and only accounted for 1.2% of the total area.Wetlands approved for restoration and wetlands already restored have been grouped in different types according to their hydrological regime. Shallow lakes cover 2985 ha, while a variety of different wetland projects ranging from areas irrigated with drainage water to restored river valleys including remeandered rivers cover 3844 ha. The mean nitrogen removal for all projects was estimated to 259 kg N ha−1 year−1, while results from the monitoring programme have shown that wetlands remove between 39 and 372 kg N ha−1 year−1.