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Eden 62 du côté technique

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

Grasslands and heathlands

Why grasslands and heathlands are important for the Département

  • They are rare or exceptional environments in the Département
  • These environments are home to a wide range of remarkable plant and animal-life
  • They form a rich landscape

Major conservation and public access projects

  • Trimming of bushes (to limit natural overgrowth);
  • Extensive grazing by sheep and cattle;
  • Cutting and removal of the grasses so as to maintain a low trophic level, thereby ensuring the growth of certain types of typical vegetation;
  • Soil transfer of certain areas of heathland, so as to bring the seed bank buried under the earth to the surface;
  • Organising of public access

A Few Statistics

  • The grasslands account for less than 1% of the Département’s territory (approximately 1.700 ha);
  • 33% of the Département's grasslands are located within the ENS (SIGALE, 2012);
  • Only 4% of the Pas-de-Calais’ ENS are covered by grasslands
  • The heathlands represent less than 1% of the Départements’ surface area (55 ha only) and also less than 1% of the ENS

Once used for grazing land, the grasslands and heathlands have suffered from agricultural decline following the abandonment of grazing, which no longer meets the demands of modern agriculture. These environments are dependent on an ecological management based on their use as grazing land.

Today, the heathlands and grasslands conserved within ENS are spread out over several sites. The heathlands only make up the predominant habitat on 2 ENS in the Pas-de-Calais (the Plateau des Landes Reserve and Pré Marly), which is a good reason for their conservation.

Without proper management, grassy and heathland environments can quickly be overgrown by bushes and thicket, which support a lower biodiversity than open land.

Cross-leaved heath (Erica tetralix L.) can only be found in the ENS Plateau des Landes Regional Nature Reserve. On a regional level, the only other place it is known to be growing is in the Montreuillois. This remarkable species thrives on the wet heath and drying peat bogs.
Mont-Pelé & Mont Hulin boast 11 species of orchid, including the Fly orchid (Ophrys insectifera), a remarkable and protected species in the region.

Biodiversity

Importance for Insects

  • 88 species , including 25 remarkable ones;
  • 2 sites (Mont Pelé & Mont Hulin and Plateau des Landes) are visited by more than 30 species of Butterflies, including 5 remarkable ones, which are dependent on this type of environment, including the Silver-studded Blue (Plebejus argus) or even the Dingy Skipper  (Erynnis tages);
  • Dragonflies are not really concerned by this type of environment unless there are ponds nearby (more than 25 species can be found on the Plateau des Landes).
  • There is a high level of diversity of species of Crickets and Grasshoppers in particularly favourable environments. (The Bog Bush Cricket, Metrioptera brachyptera, the Mottled Grasshopper Myrmeleotettix maculatus, etc.).

Importance for Butterflies, and Grasshoppers

Food source for Birds

Importance for Amphibians and Reptiles

  • These types of habitats are not particularly suitable for amphibians;
  • There is a wide diversity of reptiles since the right conditions are present in these habitats for these groups to make optimal use of them (exposition, food source, shelter) 5 species, including 4 remarkable ones;

Importance for reptiles, including the Common European Adder (Vipera berus)

Importance for Birds

  • 212 species of Birds, including 47 that are remarkable (Northern Wheatear Oenanthe oenanthe, Woodlark Lullula arborea, etc.).
  • They are Ideal environments for supporting species that enjoy wide, open spaces. There is a relatively good level of diversity depending on the different sites;
  • They are important on a regional level for the conservation of the Stone Curlew (Burhinus oedicnemus) (at Cap Blanc-Nez);
  • They support a wealth of insects important for the feeding of passerines.

They are of major importance for animals associated with open environments which depend on insects as their preferred prey.

Importance for Mammals

  • 21 species of land-dwelling Mammal (4 of which are remarkable) and 10 species of chiroptera
  • They are favourable environments for small insectivorous mammals (shrews);
  • They support many small and medium-sized mammals (used for hunting & shelter), including, for example, the European rabbit (Oryctolagus cuniculus), which maintains grasslands by limiting the development of the vegetation;
  • Finally, the grasslands and heathlands constitute hunting areas much sought after by chiroptera.

They are important as feeding grounds and shelter

Importance for Flora and related environments

  • 790 plant species, including 56 moderately remarkable ones and 41 of the most remarkable.
  • Depending on their exposition, soil type and climatic conditions, the grasslands can be classed into different types: chalk grasslands, dune grasslands, marly grasslands, wet grasslands, calamine grasslands, acidophil grasslands etc. Depending on the different criteria, they develop specific plant-life, namely numerous species of orchids, in the case of the grasslands;
  • The heathlands are particular types of vegetation that develop on very poor and, more often than not, acid soils. They are very rare in the region and can only be found over a few hectares of land. Hygrophilous heathland are scarcer still; the plant-life which grows there is highly adapted, including notably the Common Heather (Calluna vulgaris), the Bell Heather (Erica cinerea) and the Cross-Leaved Heath (Erica tetralix), etc.

The wide diversity of grasslands are conducive to specific plant life including numerous protected and threatened species

Heathland habitats supporting specific types of threatened and protected plant life are extremely rare in the region

Diversity of grassland and heathland environments found in the ENS

Six principal types of dry grasslands can be found in the Département’s ENS:

Chalk grasslands (present for example at Mont Pelé & Mont Hulin and at Cap Blanc-Nez);

Dune grasslands present on the coastline (examples include the Dunes d’Ecault, Dunes de Berck or Pré Marly);

The aerohalin grasslands established on the cliffs of the Capes (examples include the Cap d'Alprech);

Grasslands growing on the shale of slag heaps (present for example on the sites Bois d'Epinoy, Tour d’Horloge, the Gare d’Eau, and the Terril d'Estevelles).

These environments, which have become rare or even extremely rare in the Département, are exclusively maintained by man, notably through their extensive use as grazing land. The main habitats to be found in these environments are:

Dry heathlands, a very rare habitat, maintained through practices such as mowing, grazing and soil scraping, offer an exceptional diversity of plant-life. These types of heathland can be found in the ENS at Pré Marly and Plateau des Landes.

Wet heathlands are characterised by the presence of plant species, which may be rare, even very rare in the Département, like common Heath Grass (Danthonia decumbens) or cross-leaved heath (Erica tetralix). These types of heathlands are very rare in the Département; they can be found in the ENS at the Plateau des Landes.

The grasslands are largely managed through their use as grazing land, thereby limiting the growth of trees. Temporary or permanent ponds and former settling basins appeal greatly to Amphibians and Odonata, typically at home in this type of environment.

Cap Blanc-Nez: Finding the right balance between public access and protecting the grassland environment.
Cap Blanc-Nez “Grand Site National” is an important tourist attraction for the region. One of the conservation issues at the site is to ensure public access while at the same time respecting the natural heritage in optimally safe conditions. This entails setting restricted access to certain areas within the now protected grasslands.
This decision is closely linked to the reuse of the site for grazing. In 2009, 150 sheep of the local “Boulonnais” breed were able to graze on and thus help maintain the Mont d’Hubert, and in 2010, a rotating grazing area was set up and was used by 320 sheep for the whole of the Blanc-Nez, then 530 sheep in 2011. This is only example of such large-scale conservation work, where chalk grasslands have been restored through the setting up of a moving grazing area in the North of France.

To learn more about grasslands and heathlands in the ENS.

État des connaissances de la biodiversité des ENS du Pas-de-Calais, chapitre VI.1.2, les milieux pelousaires, chapitre VI.1.3, les landes. (Only available in French)