Espace pro

Eden 62 du côté technique

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

Mining Sites

Why mining sites are important for the Département :

  • They provide sanctuaries for fauna and flora life which can find all the conditions needed to flourish (refuge, food, etc.) in this ‘man-made’ context;
  • They represent environments that are distinctive of the region providing a habitat for flora and fauna that are both emblematic and unique;
  • They are places steeped in history and memory;
  • They constitute valuable tourism and sporting assets: for family nature walks and recreational sport (such as mountain-biking and orientation), but which need to be managed to preserve local biodiversity;
  • As an educational resource (regarding coal mining & geological and natural heritage).

Main conservation and public access projects

  • Grazing by goats on slopes and on vegetation-covered shale: the aim being to contain the development of shrubs and maintain bare slopes that are ideal for reptiles, insects, and certain species of plants; the use of goat herds ensures that the fragile substrata is not disturbed;
  • Selective tree felling: to prevent overrunning by Birch or Black Locust trees (Robinia pseudoacacia);
  • Maintaining screes and other wildlife shelters;
  • Creating ponds to support certain pioneer amphibians, which have become scarce in the region;
  • Managing public access.

A few statistics

  • There are more than 400 ha of slag heaps associated with some 700 ha of abandoned coalfields and their immediate surroundings (woods, disused mining railway line, etc.). This is the case for 16 ENS in the former mining basin, including 5 slag heaps (shown on the map opposite).
  • Slag heaps make up 10 % of the ENS (around 220 ha) but less than 1 % of the Département’s total surface area.

From a historical, cultural, and ecological point of view, slag heaps are part of the region’s identity. Out of more than 330 slag heaps in the Nord-Pas de Calais region, less than half still exist today. Little by little, local government is recognizing the landscape, ecological and tourism value of these “black mountains”. Over a hundred slag heaps have been bought by the Public Land Agency. The five concerned by the present study have been granted ENS status by the Pas-de-Calais to protect their biodiversity. Over and above their considerable intrinsic ecological value, the need to maintain this historical and unique landscape was recognized internationally when UNESCO included the region’s mining basin in its world heritage list under the category "A Continuing, Organically Evolved Cultural Landscape".

The Oignies 9/9bis slag heap is a superb example of how to reuse a slag heap; with its mosaic of natural habitats and typical flora and fauna.
The Natterjack Toad (Bufo calamita), ‘inhabitant’ of pioneer environments appreciates the creation of ponds on shale.


Importance for Insects

  • 78 species of insects including 17 remarkable varieties;
  • Bare and sun-exposed areas are attractive to thermophilic species ( Grasshoppers and Crickets, like the Italian Tree Cricket, Oecanthus pellucens; and Butterflies), such as the Small Blue (Cupido minimus), which makes use of the west to east corridor across the Département that is provided by the disused mine sites;
  • Wet areas are attractive to Dragonflies, including species that are typical of pioneer environments;
  • Slag heaps constitute a vital space for wildlife in a landscape dominated by agriculture and dense urban development.

They offer an original refuge for Grasshoppers and Crickets.

Importance for Amphibians and Reptiles

  • Shale slopes are ideal for reptiles (the common Wall Lizard, Podarcis muralis). These can be found at 4 ENS (Terril de Pinchonvalles, Bois des hautois-9/9 bis, Bois Louis et d’Epenin, Bois de Lapugnoy); 3 species of reptile, each one remarkable;
  • Vernal and permanent ponds are attractive for amphibians that are typically found in pioneer environments (Natterjack Toad, Bufo calamita, Common Midwife Toad, Alytes obstetricans).This is the only place in the region where they can be found inland. 13 Species of Amphibian.

The types of species found in these environments are determined by the uniqueness of the natural conditions, i.e. thermophilic and wet pioneer environments.

Importance for Birds

  • 60 observed species, including 7 remarkable varieties that are directly dependent on open environments.
  • The Meadow Pipit (Anthus pratensis) and the Northern Wheatear (Oenanthe oenanthe), whose numbers are falling in the region, are present during their nesting periods on low-growing grasslands and on scree formations;
  • Scrubland is highly attractive for birds, and provides abundant food for migrating forest-preferring passerines.

They are very important as migration staging areas and for the pioneer species of open environments

Importance for Mammals

  • 22 species of Mammal find a haven in these environments (such as the European hare, Lepus europaeus);
  • The European Rabbit (Oryctolagus cuniculus) helps to maintain open vegetation;
  • Chiroptera (at least 4 species) enjoy shelter (wooded environments) and a source of food (e.g. wet areas on and adjacent to mine sites).

They constitute areas for refuge, feeding and giving birth by certain species

Importance for Flora and related environments

  • 522 plant species including 21 remarkable varieties,7 of which are very remarkable;
  • Although man-made, certain slag heaps possess an extremely valuable plant heritage;
  • Slag heaps provide refuge or alternative environments for numerous pioneer species, such as the Strapwort (Corrigiola litoralis), and several types of Mullein (Verbascum);
  • They offer unique conditions: nutrient-poor, warm and wet soil, which are conducive to the development of specific types of habitat and plant species.

Numerous specialised species flourish thanks to the unique conditions to these areas: thermophile, wet pioneer environments, scree formations etc.

The diversity of natural habitats in former mining areas in the ENS

Disused mines located within a heavily urbanised and industrial landscape are true reservoirs of biodiversity inside a mining basin stretching for more than 120 km across the Nord Pas-de-Calais region. Today, they are an essential part of the ecological corridor in the region’s former mining areas.

These ENS contain diverse natural habitats:
Sun-facing exposed bare slopes that are progressively colonised by pioneering thermophilic species.

Shale vegetation (Terril de Pinchonvalles, Bois d’Epinoy, etc.) that can be maintained through adapted grazing.

Abandoned land rich in flowering plants (Val du Flot, Terril d’Estevelles etc.) occurs where the soil is stable, thus providing an environment conducive to insect life.

Scrubland and wooded areas representing the most advanced stage of the vegetation naturally developing on slag heaps: they provide food and shelter for small and large fauna alike (Pinchonvalles slag heap, for example).

Vernal and permanent pools and former settling basins offer attractive environments for Amphibians and Odonata, which are typical of these environments.

Flowering areas on the slag heaps provide places of refuge and feeding for numerous insects
The Pinchonvalles slag heap is 1km750m long, and is protected by a Regional Biotope Protection Order, which preserves the diversity of its flora and fauna. Bird banding at Pinchonvalles has highlighted its importance during the migration season (the Ring Ouzel, Turdus torquatus, for example).

To learn more about the mining sites in the ENS

État des connaissances de la biodiversité des ENS du Pas-de-Calais, chapitre VI.1.5, les sites miniers. (Only available in French)