The Department categorised approximately 10 000 ha as pre-emptive areas on which it has priority in case of sale.
For about twenty years, approximately 5000 ha have been subject to a land purchase by the Department of the Pas-de-Calais (2500 ha) and the Conservatoire du Littoral (2500 ha) . This is equal to about the half of the pre-emptive areas set up by the Department.
The conservation activities concerned widely different environments :
- 650 ha of woodlands and forests,, 8 forest habitats of European interest,
-130 ha of calcareous hillsides, among which 9 habitats are of European interest
(Let’s mention for instance the opened up lawn made up of western thyme and hairy fescue (endemic lawn of the Boulonnais). This habitat, very uncommon nation-wide, is considered to be exceptional in Europe and is listed in Annex I of the Habitats guideline as a habitat of utmost importance,
- 21 000 ha of dunal environments; from the sand dune to the wooded one,from the Picard dune to the Flemish one, more than 25 habitats have been identified as being of European interest.
- 200 ha of moorlands having widely different typologies (from the dry moor to the wet one, from the grass land to the wooded one, among which 8 moor Habitats of European interest),
- 430 ha of marshlands ; audomarois marsh, marsh of Guines, marsh of Tardinghem, with more than 15 habitats of European interest.
- About 300 ha of slag heaps fare subject to an action of conservation.
The species involving an important patrimonial stake are numerous and make up a reserve totally fundamental for the biodiversity conservation, at the departmental level or above for some of them.
- 4 species are subject to a national ; conservation plan; fen orchid, grass-of-parnassus, bitter gentian, slender marsh bedstraw.
Eden 62 is responsible for almost all the fen orchids areas in the department.
- 12 protected species nation-wide
- 117 protected species region-wide
It is also important to carry out our action according to other criteria such as the rarity index; 50 species existing on the Espaces Naturels Sensibles are considered to be « exceptional» and 106 to be « very uncommon»
In the natural areas of the department, there are :
- 12 species of amphibians out of 15 known in the region,
- 5 species of reptiles of the region
- 11 species of bats out of 18 known in the region. For instance on Mount Pelé in the town of Desvres, more than 60 subjects have been observed, in comparison to 10 subjects observed few years ago, thanks to development works.
As to the bird species, 22 protected species on a European scale (Annex I of the guideline of birds) nest in the Espaces Naturels Sensibles, which corresponds to a quarter of the species of Annex I in France. Let’s mention the Eurasian Bittern, the little Bittern, the short-eared Owl, the marsh Harrier or even the black-winged Stilt…