Réserve naturelle régionale des Annelles, Lains et Pont Pinnet: Mapped Landscape and Geography

The reserve is best known for the unusually high habitat diversity packed into a small post-mining landscape, where peat bogs, willow marshes, dry grasslands, and heavy-metal-tolerant plant communities coexist within 14 hectares. It is especially notable for its so-called "vieille tourbière," the Escarpelle coal-shale terril, and its populations of metallophytes such as Haller's sea-thrift (Armeria maritima subsp. halleri). It is also recognized for the density and quality of its amphibian fauna, with nine species recorded in a network of ponds and ditches, including the protected great crested newt, and for the rare aquatic plants such as common bladderwort and coloured pondweed that survive in its mineral-rich waters.

The lands now protected by the reserve were once part of a broader wetland system of wet meadows and marshes, much of which was filled in or altered during the 19th and 20th centuries as a result of coal mining and the canalization of the Scarpe River. Mining spoil and coal-shale deposits progressively overlaid and reshaped part of these former wet zones, leaving behind a patchwork of dry, moist, and peaty habitats that gradually developed their own ecological character.

Local recognition of the natural significance of these relict habitats grew steadily, and a project to give them formal protection was carried forward by the commune of Roost-Warendin and the local naturalist association Roost-Warendin Nature. The proposal was submitted to the Nord-Pas-de-Calais regional council, which accepted the classification. The reserve was officially created on 4 October 2010, becoming one of the regional nature reserves of the Hauts-de-France region. Since its creation, the site has been managed by the Conservatoire d'espaces naturels du Nord et du Pas-de-Calais, which inaugurated on-site signage in April 2011 and developed a management plan to address invasive species, eutrophication, and visitor pressure.

In parallel, the reserve has become part of a broader regional effort to recapture biodiversity value on post-industrial and post-mining land, demonstrating how formerly degraded ground can support peatland flora, amphibian populations, and rare metallophytes when protection and active management are combined.

The landscape of the reserve is shaped by its position along the Scarpe valley and by its industrial past. The protected area lies between the canalized Scarpe River and the Scarpe diversion canal, on rather flat lowland terrain typical of the northern French coal basin. The canalized watercourses, ditches, ponds, and relict wet meadows produce a visually fragmented but ecologically varied patchwork.

The most visible physical feature of the site is the Escarpelle terril, a coal-shale tip built up by historical mining activity. Its dry, hot, stony slopes contrast sharply with the wet marshes, willow stands, and peatland that occupy lower-lying sections of the reserve. The peatland, locally called the vieille tourbière, is one of the oldest surviving landscape elements of the site, while the wet willow woodlands of Lains and Pont Pinnet represent a transitional stage between open marsh and dry ground.

The result is a layered landscape in which dark shale mounds, open water, wet woodland, and patches of dry ruderal vegetation lie within very short distances of each other. This juxtaposition defines the reserve's distinctive character and strongly influences the distribution of its plant and animal communities.

The ecological richness of the reserve is closely linked to the diversity of its habitats within a very small area. The site supports seven habitat types listed under Annex I of the European Habitats Directive and around 26 broadly defined natural habitats, ranging from relict peatland and wet willow woodland to dry grasslands, ponds, ditches, and metalliferous vegetation. Roughly a quarter of recognized plant formations on the reserve are considered of heritage value in the Nord-Pas-de-Calais region.

A key feature of the site's ecology is the presence of metalliferous grasslands, locally known as pelouses calaminaires. These small patches of heavy-metal-tolerant vegetation have developed on contaminated substrate, and they support specialized metallophyte species capable of accumulating zinc, lead, and cadmium. They include strict metallophytes such as bladder campion and Haller's sea-thrift (Armeria maritima subsp. halleri).

The other major ecological signature of the reserve is its relict peatland and wet zone network. Ponds, ditches, and the wet willow stands of Lains and Pont Pinnet together preserve one of the last fragments of what was once a continuous wetland system along the Scarpe. These wet habitats support carnivorous aquatic plants such as common bladderwort, alkaline-water pondweeds, and a significant amphibian community, while also acting as refuges for invertebrates, including dragonflies and butterflies.

The reserve supports a remarkably dense fauna for its size, reflecting the diversity of habitats packed into 14 hectares. Birds are particularly well documented, with around 60 species observed on or around the site, of which roughly 48 are considered to nest there. Among the most noteworthy breeding species are bluethroat, water rail, common kingfisher, and European turtle dove.

The reserve's amphibian fauna is one of its principal natural assets. Inventories conducted between 2002 and 2008 identified nine species within its ponds, ditches, and wet woodland, representing a large share of the regional amphibian fauna. The most prominent species is the great crested newt, a European-protected amphibian that breeds in the ponds of Pont Pinnet.

Dragonflies are also well represented, with 19 species recorded on the site, more than 30 percent of regional diversity. Several of these, including the large aeshna dragonfly and the white-faced darter, are considered rare in the Nord-Pas-de-Calais region. Mammals are less thoroughly documented, but include small mammals, bats, and roe deer-like micromammals inhabiting the site's edges. Forty-eight species of breeding birds, nine amphibians, and nineteen dragonflies combine to give the reserve an exceptionally high faunal density for a small protected area.

The conservation significance of the reserve lies in its role as a refuge for a wide range of habitats and species within one of the most heavily industrialized landscapes of northern France. By protecting what remains of relict peatland, metalliferous grasslands, wet willow woodlands, and ponds, the reserve preserves ecological features that have largely disappeared from the surrounding Scarpe valley and mining basin.

Its designation in 2010 was motivated in part by a desire to limit the continuing pressures on these habitats. Heavy-metal contamination linked to past mining and metallurgical activity is still detectable in parts of the reserve, and eutrophication, the spread of invasive plant species, woody encroachment, and occasional overuse by visitors have all been identified as active or potential threats.

Management by the Conservatoire d'espaces naturels du Nord et du Pas-de-Calais, supported by the local association Roost-Warendin Nature, focuses on maintaining open habitats, controlling invasive species, monitoring water quality, and providing environmental education. The reserve is classified as an IUCN Category IV area, recognizing it as a habitat and species management area where active intervention is required to maintain its ecological values.

The reserve sits in a landscape deeply marked by the industrial and mining history of northern France. The Escarpelle terril, the adjacent mining spoil deposits, and the proximity of the former Métaleurop-Nord site and the Auby metallurgical plant all reflect a regional identity built around coal extraction and metal processing, an identity that shaped local communities, work, and land use for more than a century.

The creation of the reserve itself reflects a shift in this regional identity: a transition from a purely extractive relationship with the landscape to one that also values ecological heritage. Local involvement through the commune of Roost-Warendin and the association Roost-Warendin Nature was central to the reserve's creation, and the site is used today as a setting for environmental education, guided visits, and citizen engagement with the natural heritage of a previously overlooked industrial landscape. The reserve is also accessible to people with reduced mobility, reinforcing its role as a shared local resource.

Within its 14 hectares, the reserve concentrates more than 26 natural habitats, 236 vascular plant species, 48 breeding bird species, 9 amphibian species, 19 dragonfly species, and 24 butterfly species, giving it an unusually high biodiversity density for a regional nature reserve of this size. Its Escarpelle terril, vieille tourbière, and Pont Pinnet ponds are the three signature elements that together define its character.

Equally distinctive is the coexistence of relict peatland, wet willow woodland, dry grassland, and metalliferous vegetation within walking distance of one another, supported by careful management from the Conservatoire d'espaces naturels du Nord et du Pas-de-Calais. The protected area stands out as a model of how post-mining land can be transformed into a meaningful long-term refuge for biodiversity in an otherwise heavily industrialized region.

The reserve can be appreciated throughout much of the year, with each season offering a different perspective on its habitats. Spring and early summer are generally the most rewarding periods for observing wetland vegetation, dragonflies, and breeding birds around the ponds of Pont Pinnet and the wet willow woodlands of Lains, when amphibian activity and aquatic plant flowering are at their peak. Late spring also brings the richest display of metallophyte and thermophile flora on the Escarpelle terril.

Summer visits offer the chance to observe dragonflies and the full development of reedbed and grassland vegetation, while autumn brings fruiting willow woodlands and a quieter atmosphere conducive to observing fungi, including the thermophile species associated with former mining substrates. Winter visits reveal the contrast between the steeper brown slopes of the terril and the quieter wet zones, although wildlife observation is more limited. The reserve's accessibility for people with reduced mobility means it is suitable for short visits in any mild season.