Restoration of Dune Vegetation in the Netherlands

The biodiversity of the open dune landscapes in the Netherlands is gradually declining due to less intensive use of the dunes, increased deposition of atmospheric nitrogen (5–10 fold increase between 1939 and 1981), and a growing need of drinking water for urban areas that led to desiccation of dune wetlands . Since 1990, numerous restoration projects have been carried out in the coastal area to curb the loss of biodiversity in the dune areas. Grazing was reintroduced in the dry dunes, the technique for drinking water production was modified, rewetting and removing of acidified top soils was applied in interdunal wetlands, and on a small-scale aeolian dynamics was re-initiated to stimulate sand blowing in the dunes. Restoration measures in the dune slacks were generally more successful than in the dry dunes. Most typical, dune slack species returned when hydrological conditions were appropriate. In the dry dunes a few typical dune species returned after restoration measures. Grass encroachment and rapid growth of shrubs could not be stopped by only grazing, due to too high availability of nutrients in the soil and many typical dune species have become so rare that they apparently could not reach the restoration areas.