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Eden 62 du côté technique

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

Dune environnments

Why dune environments are important for the Département

  • Dune environments are typical of the Département and support regionally unique and emblematic fauna and flora;
  • They represent a diversity of habitats (Flemish and Picardian dunes) and offer highly complementary places to live for animal and plant species;
  • They are important reservoirs of biodiversity in a context of massive pressure from coastal urban sprawl;
  • They represent a true ecological continuum interacting with the marine environment;
  • They are a tourism asset for visitors seeking locations for family nature walks, sporting recreation and leisure, especially associated with the Department’s popular beaches.

Main conservation and public access projects for dune environments

  • Extensive grazing in public access areas in order to contain the invasion of sea-buckthorn and gorse;
  • Creating ‘no-go’ areas in certain locations to protect against disturbance from heavy tourism, and dedicated routes provided for visitors;
  • Maintaining the vertical and compositional diversification of wooded areas (opening of clearings, strengthening of edges, conversion of pine forests, etc.);
  • Maintaining the dune slacks (29 hectares in total) by mowing and removing cuttings and also water level monitoring in order to preserve Amphibians and other species found in these unique wet areas.

A Few Statistics

  • Dune environments make up less than 1 % of the Département’s surface area (around 4,600 ha).
  • 43.5 % of the Département’s dunes are ENS protected sites.
  • Dune habitats make up 39 % of ENS (approx. 2 000 ha), thanks to the partnership between the Conseil général and the Conservatoire du Littoral.
  • Dune habitats often cover a substantial area: the Dunes of Mont Saint-Frieux and the Baie de Canche National Nature Reserve together cover an almost unbroken 1,000 hectares.

Dune environments are ‘coeurs de nature’ (hearts of nature), running along the entire length of the Department’s coast and play an important role as natural corridors. Dunes may be more or less mobile, their mobility depending on the type of vegetation they support and human actions. In addition to natural change, dunes have been subjected to intense pressure from coastal urbanisation. The Pas de-Calais has been relatively fortunate. It has benefited from the coast protection law (from 1986), which has enabled the partnership between the Conservatoire du Littoral and the Conseil Général to intervene to preserve these environments.

The Spurge Hawk-Moth Caterpillar (Hyles euphorbiae) on its host plant, the Sea Spurge (Euphorbia paralias).
The very rare Dune Pansy (Viola curtisii) grows on embryonic dunes.

The diversity of natural dune habitats in the ENS.

Dunes are transitional environments (a sea/land interface), which explains the wealth of the nature they support. The distribution of animal and plant life present is influenced by the degree of exposure to the elements. Their conditions are similar to those of slag heaps, or limestone hillsides and often support warm-loving species.

White dunes (often bare sand) provide a habitat in which pioneering plants and animal species take hold. White dunes can be found higher up on the shore and can vary in size depending on the location. They are both fragile and unstable. Such dunes can be found for example at the Dunes de Slack.

Grey dunes develop from white dunes and are characterised by their herbaceous vegetation. They are inhabited, for example, by Grasshoppers, as well as the European Rabbit (Oryctolagus cuniculus) which helps to maintain this habitat by preventing thickets of shrubs from spreading. This type of environment can be found for example at Mont Saint-Frieux or at the Baie de Canche.

Scrub Dunes, which are covered in shrubs/bushes, including berry-rich varieties, are an attractive habitat for numerous passerines (Warblers, and Thrushes in particular) during their migration. From a geomorphological perspective, this type of dune is relatively stable (the Dunes d’Ecault, for example).

Deciduous wooded dunes represent the most advanced development stage of naturally occurring dune plant life. Set back well away from the beach, behind the scrub dunes, they provide an attractive environment for all categories of fauna. This is the case for example at the Baie de Canche.

Man-made coniferous wooded dunes (resinous plantations) may be located very close to the beach; the two purposes of the conifer plantations being to pin the sand in place and to generate income, both of which were intimately linked to this time period. They can be found at Mont Saint-Frieux or at the Dunes de Slack.

Dune slacks are wedged between the different types of dune. Their particular characteristics depend on the precise topography of the location and groundwater. Slacks are home to diverse animal and plant life, including some species that are rare and endangered at regional level or even more widely (e.g. the Fen Orchid, Liparis loeselii).

The Baie de Canche Reserve (photo above) and the dunes of Mont-Saint-Frieux are remarkable and complementary sites that form a vast reservoir of biodiversity.
The European Nightjar (Caprimulgus europaeus) is emblematic of the dune habitats. • It is a species of European interest • quite rare and in decline in the region • 80% of its population visits the ENS located in the Département’s dune areas • over 60 % of its population can be found at the Baie de Canche and Mont Saint-Frieux.

To learn more about dune environments in the ENS

État des connaissances de la biodiversité des ENS du Pas-de-Calais, chapitre VI.1.1, les milieux dunaires. (Only available in French)


Importance for Insects

  • 111 species of insect, 46 of which are remarkable;
  • They support between 25 and 40 species of Butterfly at the Baie de Canche Reserve and at Mont-Saint-Frieux.
  • They support an exceptional diversity of Dragonflies with between 25 and 35 species depending on the site, including 10 remarkable species;
  • They are important for certain species of Bush-Cricket or Grasshopper, the majority of which are dependent on coastal habitats. (e.g.: the Grey Bush Cricket Platycleis albopunctata, the Field Cricket Gryllus campestris, and the Mottled Grasshopper Myrmeleotettix maculatus).

Dune Environments are highly important for all insect groups thanks to the wide range of conditions they offer, ranging from the wettest to the driest, and from pioneer to wooded environments.

The Map/ Araschnia levana

Importance for Amphibians and Reptiles

  • 4 species of reptile (including 3 remarkable ones) and 14 species of Amphibian ( 8 of which are remarkable;
  • The dune slacks offer great diversity;
  • They represent a rich and important natural heritage, supporting pioneering amphibian species.

The presence of this group is an indicator of the quality of thermophilic and wet habitats.

The Common Toad /Bufo bufo

Importance for Birds

  • 125 species observed, including 39 remarkable varieties during their nesting season;
  • The dunes support many emblematic species (including the European Nightjar Caprimulgus europaeus,the Woodlark, Lullula arborea, the Common Redpole, Carduelis flammea);
  • Scrub dunes offer attractive habitats and abundant food for forest passerines during their migration;
  • Numerous locations offer attractive staging areas for migratory birds (these locations are used for bird banding operations).

They are of major importance for nesting and migration.

The Eurasian Woodcock/ Scolopax rusticola

Importance for Mammals

  • 32 species of mammal, 8 of which are remarkable and 13 species of bat
  • The dune environments offer a diversity of habitats and a surface area able to support numerous species. They can be used as roaming territories, hunting grounds, and havens in contexts that are subject to multiple sources of disruption.
  • They constitute areas for refuge, feeding, even for giving birth for certain species

Refuge zones, hunting/feeding grounds, even reproduction for certain species

Wood Warbler /Phylloscopus sibilatrix

Importance for Fish

  • The dune environments rarely incorporate bodies of water (Baie de Canche Nature Reserve) but which nonetheless provide a habitat for 16 species of fish.
Wood Warbler /Phylloscopus sibilatrix

Importance for Flora and associated environments

  • 1037 plant species, including 85 that are moderately remarkable and 63 very remarkable species;
  • The plant heritage of the coastal dunes in the Nord-Pas de Calais is exceptional. It includes species that are protected at region and European scales, such as Blue Lyme Grass (Leymus arenarius), the Fen Orchid (Liparis loeselii) (a species that is regulated by the National Action Plan), and the Dune Pansy (Viola curtisii), among others.
  • They offer diverse, original and specialized habitats.

They are very important for plants and support extremely rich and diverse habitats.