Réserve naturelle nationale de la dune Marchand: Mapped Coastal Landscapes and Protected Geography

The Dune Marchand was formally established as a French Réserve naturelle nationale on 11 December 1974, through a ministerial order that recognised the scientific and ecological value of the Flemish dunes east of Dunkirk. The initial perimeter covered around 83 hectares of mobile and fixed dunes, dune slacks, and adjacent coastal vegetation.

In 1990 a new decree replaced the original order, reclassifying and reaffirming the reserve under the modernised French nature reserve framework. A more recent decree of 26 February 2024 extended the perimeter to approximately 113 hectares, broadening protection over additional dune habitat that had become ecologically significant since the original designation.

Alongside this statutory protection, the Conservatoire du littoral acquired more than 100 hectares of dune land in the area between 1980 and 2004, securing long-term conservation of a wider dune landscape around the reserve. In 2008, a volunteer work camp organised with the association CONCORDIA closed off several wartime bunkers within the dune to improve site safety and to convert them into refuges for bats and amphibians, an initiative coordinated with the Coordination mammologique du Nord. In 2003 the site was also integrated into the European Natura 2000 network as a Site of Community Importance.

The landscape of the Dune Marchand is shaped by the relentless action of wind and sea along the southern North Sea coast. The dune ridge runs parallel to the shoreline and rises in a long, narrow band flanked on one side by the beach and on the other by lower-lying reclaimed and semi-natural land. Because the coastal winds here are strong and relatively constant, the dunes are unusually dynamic, with active scouring that continually reshapes the surface.

Within the dune mass, characteristic hollows and depressions have been dug out by the wind. These slacks sit at a lower level than the surrounding sand and, in many cases, retain moisture close to the surface. The result is a striking alternation over short distances of dry, exposed crests and sheltered, sometimes damp basins. In winter and spring the slacks can hold temporary pools, while in summer they support distinct plant communities adapted to alternating wet and dry conditions.

Vegetation patterns follow this topography tightly. The most exposed faces are stabilised by marram grass and other pioneer plants, while the lee sides and older dunes carry denser cover of shrubs and small trees, including grey poplar, alder, ash, and flowering ash, interspersed with thickets of sea buckthorn. Where the dunes meet the backshore, the landscape transitions into wetter dune slack vegetation, reedbeds, and patches of marshy ground, giving the reserve a layered coastal scenery that is rare on this part of the French coast.

The ecological character of the Dune Marchand is defined by the coexistence of dry and wet dune habitats within a single protected perimeter. The mobile dunes and fixed grey dunes together preserve the classic sequence of natural dune vegetation that once dominated this stretch of coast, while the wind-scoured slacks introduce a contrasting humid microclimate that supports plants normally absent from open dune landscapes. Few French coastal sites combine these elements at such close range, which is why the reserve has long been treated as a reference site for Flemish dune ecology.

The vegetation includes the usual building blocks of a North Sea dune system: marram grass anchoring the seaward face, reed clumps in damper zones, and a wooded back-dune with grey poplar, alder, ash, flowering ash, and sea buckthorn thickets. Within the slacks and older fixed dunes, a notably diverse community of flowering plants persists, including multiple orchid species, marsh grass of Parnassus, helleborines, gentianellas, and small colonies of boreal relicts such as the Curtis's violet and pyrola.

A particular ecological signature of the site is the presence of the Choin noirâtre, a plant of conservation interest considered endemic to the regional dune context. The combination of 337 recorded plant species, of which two are protected at the national level, reflects how the topography of dune and slack creates many small, distinct microhabitats that together sustain a much richer flora than the reserve's modest size would suggest.

Fauna at the Dune Marchand is diverse, partly because the dune's varied habitats offer very different living conditions within a small area. The reserve documents 162 vertebrate species, including six amphibians, a reptile, a range of mammals, and especially a rich bird community of roughly 140 species, of which about 35 are confirmed breeders.

Amphibians are a particular highlight. The wet dune slacks and damp depressions support natterjack toads and great crested newts, both species of conservation concern that depend on the open, sun-warmed pools that form after wind scouring. Mammals include bat species that have begun roosting in the wartime bunkers that were sealed off for their protection in 2008, alongside other small mammals typical of dune scrub and woodland edges.

The birdlife brings together residents and migrants. Breeding species include common nightingale, green woodpecker, willow warbler, common whitethroat, European stonechat, common linnet, thrushes, bramblings, and snow buntings in winter, while the wider dune landscape provides habitat for many passage migrants. Along the adjacent shoreline, harbour seals regularly use the area for reproduction, linking the reserve's dune ecosystem with the marine environment of the North Sea.

The Dune Marchand is significant for conservation because it safeguards one of the few remaining stretches of the French North Sea coast where the natural dune vegetation sequence is still essentially complete. This continuity is increasingly rare in northern France, where urbanisation, tourism infrastructure, and coastal defence works have fragmented many dune systems. By protecting mobile dunes, fixed dunes, dune slacks, and adjacent woodland patches under a single national designation, the reserve maintains the ecological processes that drive dune dynamics and allow specialised species to persist.

Its inclusion in the Natura 2000 network as a Site of Community Importance in 2003 reflects its European-level importance for dune habitats. The reserve also sits within a broader conservation landscape built up since 1980 by the Conservatoire du littoral, which gradually acquired surrounding dune land, and is part of the Grand site des Dunes de Flandre, an integrated management framework for the whole Flemish dune coast.

Specific management actions have targeted the most fragile features of the site. The 2008 conversion of wartime bunkers into shelters for bats and amphibians is a clear example of practical habitat creation inside the reserve. Maintaining public access on marked paths, while keeping sensitive slacks and breeding areas undisturbed, is central to balancing conservation with education and public engagement.

The Dune Marchand stands out for bringing together four rare qualities on a small coastal footprint: a near-complete sequence of natural French dune vegetation; wind-scoured slacks that support both dry and damp specialist flora; a productive mix of breeding songbirds, amphibians, bats, and harbour seals; and an active network of national, departmental, and European conservation protections.

Its compact scale, combined with its proximity to Dunkirk and the Belgian border, makes it both an ecological refugium and a key node in the wider Flemish dune landscape managed with the Conservatoire du littoral and the Natura 2000 network.

The Dune Marchand can be experienced in different ways through the seasons, with the character of the dunes shifting noticeably between warmer and cooler months. In late spring and summer, the dune slacks fill with flowering plants and orchids, and amphibians are most active in the damp depressions, while the seaward dunes are at their busiest with breeding birds and insects.

In autumn and winter, the vegetation dies back and the bare sand and dune structures become more visible, offering a clearer sense of the underlying dune morphology shaped by wind. Winter is also a season when certain migrant birds, such as snow buntings and bramblings, are more likely to be encountered along the coast. Access throughout the year relies on staying on marked paths, so any visit is best planned around calm weather given the exposed coastal setting.