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Rapport sur l'état des connaissances de la biodiversité 2000-2010

Natural habitats

The Natural Habitats found in the ENS

The ENS can be found across the whole Département, from the coast to the mining region, and are home to a variety of natural habitats. Dune and woodland habitats (or similar) tend to be dominant, however.

The pie-chart, opposite, shows the distribution of the types of pre-dominant natural environments within the ENS. These environments support many rare, sensitive and even threatened habitats and are therefore protected.

Distribution of the major types of environments within the ENS across the Pas-de-Calais (according to ARCH, 2009)

The natural habitats are especially diversified in the region and are managed so as to maintain ecological niches and preserve their extraordinary biodiversity. Each of the major types of natural environments found within the ENS provide habitats of European interest:

  • 650 ha of woodlands and forests, including 8 woodland habitats which are of European interest. (e.g. ENS at the Bois de Maroeuil, Bois Louis & d’Epenin, and Bois d’Haringzelles, etc.);
  • 350 ha of natural grasslands, including 9 habitats which are of European interest. (e.g. ENS at Cap Blanc-Nez, Mont Pelé & Hulin, and Pointe de la Crèche, etc.) ;
  • 2100 ha of dune habitats, including 25 habitats, which are of European interest. (e.g. ENS at Baie de Wissant, Dunes de Slack, Platier d’Oye);
  • Less than 5 ha of dry heathland of very diversified typologies. (The ENS at Pré Marly and Plateau des Landes), which support 8 habitats of European interest;
  • 430 ha of wetlands (Saint-Omer marshlands, Marais de Guînes), including more than 15 habitats of European interest (ENS at Marais Audomarois, Marais de Guînes…) ;
  • More than 400 ha of slag heaps, at least 7 of which are habitats which have regional and European heritage interest. (e.g. ENS at the Terril de Pinchonvalles, Bois des Hautois (9/9bis), and the Terril d'Estevelles).

A Few Statistics

  • The ENS can support up to thirty different habitats, thus offering varied ecological niches for local Fauna and the Flora.
  • 45 out of the 50 of the region’s natural heritage habitats are to be found in the ENS.
  • Some natural habitats are only found in a very small number of ENS (sometimes even in only 1 ENS for some types of costal vegetation) or in a very large number (there are 34 references to certain watery herbaria in the Département’s ENS).

The term “natural habitat” is a concept used in ecology to describe the features that make up an “environment” in which a population of a particular species (or a group of species) normally lives and can flourish. The features of the environment are defined by the physical and biological factors that are necessary for the survival of this species (or groups of species). Certain habitats qualify as “Habitats of (EU) Community Interest” when, upon their surface distribution being reduced, they are threatened or represent a remarkable example of the features that make up one or more of the nine European bio-geographic areas. In this case, they earn a designation as sites in NATURA 2000 (Zone Special conservation network).


Knowledge about the Fungus within ENS, but more generally within the Pas-de-Calais is, because of the reduced importance placed on inventorying fungi compared to other flora, and the lack of regional specialists, still rather fragmented. This group is poorly sampled; not all the Pas-de-Calais’ ENS have yet been surveyed.

But there are a few figures:

  • More than 1,700 pieces of data on the ENS relating to mushrooms;
  • 1,263 out of the 6,000 species currently identified in the Nord-Pas de Calais, representing 21% of the regional fungi:
  • 182 remarkable species in the ENS ;
  • Mont Saint Frieux: 712 known species
  • Marais de Condette: 230 known species
  • Ravin Pitendal and Waroquerie: 166 known species


The four richest sites in terms of remarkable species (more than 20) are:

  • The Baie de Canche Nature Reserve (23 species), which is home to exceptional or species endangered at the regional level like the sea wormwood (Artemisia maritima L.) or Moonwort (Botrychium lunaria);
  • The Platier d' Oye Reserve (22 species), which is home to exceptional species that are protected at national level like Pedunculate Sea-purslane (Halimione pedunculata), or Ray’s Knot-grass (Polygonum oxyspermum subsp. raii);
  • The Mont Saint-Frieux (21 species) which is home to critically endangered species, for example, the Sword-leaved Helleborine (Cephalanthera longifolia), a species living on forest edges and calcicolous forests, and the Military Orchid (Orchis militaris) which grows mainly on chalk grasslands;
  • The Plateau des landes Nature Reserve (20 species), which supports some of the region’s vulnerable species, like the exceptional Bell Heather (Erica cinerea), or the very rare Cross-leaved heath (Erica tetralix).
A species listed in appendix II of the Habitat-Fauna Flora, Directive, in addition to being included in the National Action plan (out of the 4 species falling into this category on a regional level): The Fen orchid (Liparis loeselii).
Nearly 70,000 pieces of data about 1180 plant species known in the Pas-de-Calais' ENS, accounting for 70% of the regional diversity.
Nearly 50% of the regions’ heritage species can be found in the ENS (406 species).

To learn more about the natural habitats, Flora and Fungi in the ENS.

État des connaissances de la biodiversité des ENS du Pas-de-Calais, chapitre IV.1, Les habitats naturels – IV.2, La Fonge - IV.3, La Flore. (Only available in French)