All too often absent from environmental debates and little-known by the general public, wetlands are nevertheless essential, rich and precious natural environments. In Luxembourg, these areas play a key role in maintaining biodiversity and provide numerous ecosystem services that are indispensable to society.
As their name suggests, wetlands are characterized by the presence of water, either on the surface or in the ground, on a permanent or temporary basis. It's a transition zone between land and water. Whether peat bogs, flooded meadows, marshes, alluvial forests or swamps, there are many different types of wetland in Luxembourg. In 2025, the Foundation owned 610.45 hectares, including 260 water bodies across the country.
Luxembourg's wetlands, whether natural or man-made, stagnant or flowing, offer unique biotopes that are home to a remarkable diversity of flora and fauna. These environments provide refuges, breeding grounds and feeding grounds, and are home to emblematic species such as amphibians like the great crested newt(Triturus cristatus) or the green tree frog(Hyla arborea), migratory birds like the reed warbler(Acrocephalus schoenobaenus) or the barn swallow(Hirundo rustica), insects like the dragonfly, one in six of which is in danger of extinction worldwide, mammals like the beaver(Castor fiber) or the otter(Lutra lutra), and many species that depend on aquatic ecosystems for their survival.
Sites such as Cornelysmillen in the Woltz alluvial plain, Lérensmillen and the wet meadows of the Trëtterbaach valley, the Schlammwiss and the Mensder Brill ponds in the Syre alluvial plain, the Dumontshaff floodplains along the Alzette and Kiemelbaach rivers, and the Marais de Grendel in the Attert valley all play an essential role in preserving this biodiversity, whose protection is essential to maintaining the natural balance in Luxembourg.
Wetlands function like natural sponges, absorbing water during heavy rainfall and gradually releasing it during periods of drought. This unique capacity helps reduce flooding while strengthening resilience in the face of climate change.
However, these areas now face a number of threats:
- Rapid urbanization is destroying valuable habitats.
- The intensification of agriculture modifies soils and watercourses, while land drainage accelerates their degradation.
- Climate change is exacerbating these problems by disrupting water cycles and further weakening ecosystems.
- The introduction of invasive species upsets the ecological balance and endangers native flora and fauna.
The Hëllef fir d'Natur Foundation plays a central role in meeting these challenges. It incorporates wetlands into its management strategy and takes concrete action to restore and preserve them. Safeguarding wetlands requires collective action. Restoring degraded sites, strengthening protection policies and multiplying local initiatives are essential steps in reversing their decline. Protecting these ecosystems means not only preserving a precious natural heritage, but also guaranteeing vital services for the environment and for future generations.
The "Marais de Grendel" nature reserve covers an area of 4.37 hectares in the Attert valley, isolated in a modern rural landscape. Part of the European NATURA 2000 network of protected areas, it comprises a mosaic of wetland and extensive environments with areas of springs. Straddling the Belgian-Luxembourg border, it symbolizes good cross-border cooperation through joint management of an exceptional site.
At the center of the site are two sections of low marsh, with fine assemblages of narrow-leaved cottongrass(Eriophorum angustifolium), Comaret(Comarum palustre) and marsh violet(Viola palustris). The most remarkable biotope is the remnant of alkaline Molinaie, an extremely threatened habitat, including numerous rare and endangered plant species, such as Bluish Sedge(Carex panicea), Creeping Willow(Salix repens) and Broad-leaved Orchid(Dactylorhiza majalis). The eastern part of the reserve is planted with birch, alder and willow, and is home to water clover(Menyanthes trifoliata) and sedge(Carex paniculata). The reserve is home to a number of interesting bird species, both migratory and breeding, such as the Verderola(Acrocephalus palustris).
Two of the 287 cast-iron boundary markers on the Belgian-Luxembourg border, numbers 135 and 136, are located in the reserve. Inside the marsh, in the middle of the reed bed, one of the intermediate boundary stones, the limestone "LB135a", still exists in its original form.
A key management objective is to extend the area and implement targeted maintenance measures, in particular regular mowing of wet meadow vegetation. Preservation of the historical and natural heritage is also a key concern.
The reserve also serves as a place of education and discovery. It is equipped with an information panel, an observation platform for admiring the boundary markers, and a discovery trail. The trail is in need of renovation, however, due to wear and tear caused by time and visitors.
With a donation of €25, €50 or €100, you contribute directly to rebuilding the pontoons, observation trails and facilities needed to protect biodiversity and give everyone the chance to discover this unique habitat.
Let's work together to preserve this exceptional natural heritage. To make a donation or find out more :
Visit the Fondation Hëlleffir d'Natur website: www.hellefnatur.lu or make a bank transfer or standing order
IBANLU89 1111 0789 9941 0000(Com: Grendel).
All donations are tax-deductible. Please do not hesitate to contact us directly by telephone on 29 04 04 338.