This type of dune is typically located on the landward side of the white dunes and is partly stabilised by grasses and herbaceous vegetation. This dune type has been awarded special priority with regard to conservation efforts by the EU, which is indicated by the asterisk after the natural habitat type code. The grey dunes in the project area are part of a mosaic of habitats with decalcified fixed dunes, humid dune slacks and dunes with willow, buckthorn and juniper shrub. The grey dunes are often located on the south side of the west-east aligned dunes. There are two subtypes in the project area: calcareous dunes with grassland cover (green dunes) and grey dunes. The calcareous dunes are dominated by herbaceous vegetation and lichen and mosses. This type of dune is found especially at Skiverbakken, where the predominant plant species is bloody geranium, and along the west coast of Jutland between Kandestederne and Skagen Klitplantage. Burnet rose and blue hair grass are two other species linked to the calcareous dunes. The decalcified grey dunes, which are more eroded and calcium-poor than the calcareous dunes, are more widespread in the area. The grey dunes are often located on the south side of the west-east aligned dunes. The grey dunes are dominated by grasses such as grey hair-grass, and by lichen, but wild pansy and sheep’s bit scabious also catch the eye. The lichen colonies within the project area are well-established and include many species of reindeer lichen. Cetraria nivalis (snow cup lichen), which is considered a relic of the Ice Age, can also be found in various places across the area. The grey types are important for the area’s large population of sand lizards and a number of insect species such as the wart-biter (grasshopper) and the dune chafer (beetle), as well as a number of red-listed butterflies such as the Niobe fritillary. The stone flat or stone desert is a special version of grey dune. Stone flats are areas where the wind has blown away all of the sand. These areas are home to unique colonies of lichen vegetation on and in between the loose rocks, for example witch’s hair lichen (Alectoria sarmentosa), which has one of its few habitats in Denmark between the rocks on these stone flats. The decalcified dunes more commonly become overgrown with grasses, which form a dense vegetative layer. The typical grasses are wavy hair grass and wood small-reed. Other threats addressed in the project include preventing the areas from becoming overgrown with non-indigenous tree species such as lodgepole pine and mountain pine.
There are around 1,600 hectares of grey dunes and calcareous dunes at Natura2000 site 2 and around 80 hectares at Natura2000 site 1.