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

Woodlands environnments

Why woodland environments are important for the Pas-de-Calais

  • They offer havens for fauna from built-up areas and from commercial woods
  • They act as biological corridors
  • They act as carbon sinks
  • They attract tourism, yet this puts them under heavy pressure with visitors seeking locations for family nature walks, sporting recreation, and leisure.

Major conservation and public access projects

  • in-situ conserving of different forms of deadwood, including standing, fallen, or deadwood with cavities in order to encourage, in particular, saproxylic insects;
  • Developing old wooded areas as ‘pockets of senescence’, which help support the Middle Spotted Woodpecker (Dendrocopos medius);
  • Creating and maintaining woodland edges and forest paths that are beneficial to forest passerines (perching birds), insects, and Flora;
  • Promoting diversified vertical structures (i.e. vertical stratification);
  • Undertaking projects that help support fauna, such as hanging bat boxes in young woodlands and digging woodland ponds for Amphibians

A Few Statistics

  • The Nord-Pas-de-Calais is the least wooded region in France (8% of its surface area). 10% of the Département is covered by woodland ( around 100,000 ha);
  • 650 hectares of woodland areas are located in ENS, in other words, 32% of the Département’s ENS are made up of woodlands.

Woodland areas are scarce in the Pas-de-Calais. They are usually privately owned and exploited as part of the silviculture industry. Historically, this is mainly due to the Pas-de-Calais’ rich soils that led them to be cleared for agriculture from the 11th century onwards.

The conservation strategy for ENS woodland areas is therefore to manage them in such a way as to create a diversity of related habitat types capable of supporting a wide range of flora and fauna.

Today, the woodland areas are in a healthy state but they remain subject to a range of natural threats such as storms, flooding, fire, cold, drought or soil hydromorphy (saturation).

The Red Squirrel (Sciurus vulgaris) is dependent on mature woods and is vulnerable to habitat fragmentation.
It is present in fairly good numbers in woodland ENS, even those of a smaller-size.
The Fire Salamander (Salamandra salamandra) can be seen in several ENS where it can find the right combination of woodland and wet conditions that it needs to reproduce.

The diversity of natural woodland environments within the ENS

The ecological importance of woodlands stems from the mosaic of specific habitats they offer in their moss, herbaceous, shrub, and tree layers. Woodlands that are diversified both in terms of vertical structure and composition provide an even greater range of ecological niches that, over time, often develop into unique natural environments. This is why woodland management focuses on promoting a balanced habitat diversity – a goal that, in such slow growing environments, requires patience.

The different layers (moss, herb, shrub, understory, and canopy) that form the vertical structure of a woodland habitat provide ecological niches for animal and plant species.

Islands of old-growth woodland (as at Mont Saint-Frieux) are maintained so as to encourage the presence of certain species of Birds and Mammals. Mature trees provide good cavities, attracting forest-dwelling bats.

Woodland edges (such as the Bois Louis & the Bois d’Epenin) are carefully maintained since they provide a habitat for numerous animal species (hunting grounds and food for small Mammals and nesting Birds, etc.).

Maintained or even man-made clearings (such as in the Bois des Bruyères & Bois de Lapugnoy) attract Butterflies (like the Lesser Purple Emperor, for example), Grasshoppers, and Crickets.

Plots within woodlands that are managed for timber production can subsequently be left to regenerate naturally, which is conducive to the development of typical woodland species.

Forest ponds, whether natural or not (such as for example in the Forêt d’Éperleques) are vital for the survival of certain remarkable species, such as the Great Crested Newt (Triturus cristatus).

The presence of the Wood Warbler (Phylloscopus sibilatrix) is a good indicator of a healthy vertical woodland structure. It appreciates old beech and oak and light undergrowth. It has been sighted at 11 woodland ENS, with possible nests recorded at 2 sites: at the Bois d’Haringzelles and the Forêt d’Éperlecques, although only the latter offers habitats that are truly conducive to nesting.

To learn more about woodland environments in the ENS

État des connaissances de la biodiversité des ENS du Pas-de-Calais, chapitre IV.1, les habitats naturels. (Only available in French)


Importance for Insects

  • 116 insect species, including 51 remarkable species
  • Forest Butterflies are attracted to woodland edges, areas left to natural regeneration, and wetland areas
  • Woodland are less significant as a habitat for the success of Bush-Crickets or Grasshoppers, although these species are attracted to the woodland edge;
  • Dragonflies use woodlands as refuge areas and for food during their adult life cycle phase (e.g. the Bois Louis and the Bois d’Epenin have 16 species)

Woodlands edges and clearings support insect life.

The Map/ Araschnia levana

Importance for Amphibians and Reptiles

  • 5 species of Reptiles, including 4 remarkable ones and 14 species of Amphibians, including 8 that are remarkable
  • Woodlands are the preferred reproduction habitat for the Fire Salamander (Salamandra salamandra)
  • Woodlands support Amphibians throughout their lifecycle (reproduction, summering, hibernation)

Woodland projects (creation of ponds, piles of deadwood, etc.) promote the presence of Amphibians.

The Common Toad /Bufo bufo

Importance for Birds

  • 77 species of Birds, including 7 remarkable ones recorded during their nesting season can be found among the multitude of woodland fauna
  • Some species are reliable indicators of the quality of the vertical broadleaf deciduous woodland structure: the Wood Warbler (Phylloscopus sibilatrix) the Black Woodpecker (Dryocopus martius) nest in 5 woodland sites (including 2 in the mining basin);

Woodlands are invaluable as migration staging posts (for food and resting)

The Eurasian Woodcock/ Scolopax rusticola

Importance for Mammals

  • 32 species of land mammals, including 8 that are remarkable
  • Their specific diversity varies depending on the size and shape of the sites
  • Wooded areas situated in agricultural land provide Mammals with an important winter refuge (e.g. for the European Hare, Lepus europaeus)
  • They are important for micromammals
  • Woodlands ideal hunting-grounds for 11 species of chiroptera (bats)

Woodlands represent good refuge, feeding, and reproduction areas for certain species.

Importance for Flora and associated environments

  • 760 plant species including 35 quite remarkable ones and 13 that are highly remarkable
  • There are different types of woodland system in the Département: acidiphile/acidicline, calciphile and hygrophilous/hygrocline, residual woodland located in large agricultural plains, dune areas, or the system of slag heaps supporting woodland.
  • Woodland environments contain several types of vegetation linked to the dynamics of woodland growth: forests, mantles, seams, clearings and logged areas
  • Compared to other types of natural environment, such as, for example, chalk grasslands or coastal areas, the woodland vegetation in the Nord–Pas-de-Calais does not support an exceptional range of plant biodiversity. However, these woodlands and associated environments do include almost a third of the region’s flora of major natural heritage interest, such as, for example, the Scaly Male Fern (Dryopteris affinis subsp. affinis).

Woodland vegetation contributes to a high quality natural environment and also offers essential havens for numerous plant species.