Biodiversity at Lac des Miriouges: Frogs, Dragonflies & Nature Restoration

Biodiversity Thrives at Lac des Miriouges: Frogs, Dragonflies, and a Renewed Ecosystem in Crans-Montana

At an altitude of 1332 meters, Lac des Miriouges is a haven for remarkable flora and fauna. The Commune de Crans-Montana has undertaken renaturation work on its portion of the lake to strengthen the biodiversity of this nature reserve, which it shares with the Commune of Lens. These efforts aim to enhance an already valuable ecosystem, going beyond minimal regulatory requirements.

A Valuable Ecosystem and Ingenious Interventions

The forests of Switzerland boast rich biological diversity, including semi-shaded pastureland, wet woodland environments, and specialized forest associations. This heritage is protected by strict cantonal law. Lac des Miriouges, located on the communes of Lens and Crans-Montana (Chermignon sector), is classified as a nature reserve, along with its immediate surroundings. This designation prompted a revitalization project, implemented as regulatory compensation for various works. The project’s biologist, Antoine Sierro, oversaw the implementation of these measures.

One of the most significant interventions involved the extensive removal of spruce trees – which tend to dominate and reduce biodiversity – to create a wildflower meadow specifically designed to attract pollinators like bees and butterflies. This meadow compensates for the loss of meadows in the region due to construction. This biotope, rich in insects, also serves as a food source for the many dragonflies in the area.

Securing Reproduction for Amphibians

Shallow pools were excavated around the lake to provide a safe breeding ground for amphibians and dragonflies. Within the lake itself, predatory fish – rainbow trout and carp – prey on frog eggs, larvae, and tadpoles. The lake’s design, a “S”-shaped basin with a sluggish current and adjustable valve, helps control sedimentation and maintenance. The project also considered the temperature of the water from the Bisse des Miriouges (dating back to the 14th century, like the Bisse du Ro), which is too cool for amphibian reproduction, and focused on new pools fed by underground springs.

A Setting of Spruce Forests

The project unfolds within a natural setting: a spruce forest with white sedge, known for stabilizing the banks of the pools. Willows and white poplars line the shores, alongside designated trails for visitors. The ecosystem of Lac des Miriouges is a dynamic interplay of water, wooded banks, gravel beds, deadwood, and riparian vegetation – a valuable ecological asset that requires careful maintenance.

More generally, maintaining the vitality of nearby wet forest areas is crucial for the future of many animal and plant species. Approximately 70% of Swiss amphibians depend on these microclimates.

Local Wildlife: From Frogs to Dragonflies

Lac des Miriouges is home to dragonflies, the common frog (sometimes found at altitudes over 2800 meters), the viviparous lizard, and migratory birds like the little egret and the grey heron. The surprising aquatic beetle, which swims on its back with paddle-like legs and can also fly, also inhabits the lake. These species thrive in the wetlands and reed beds.

The deeper waters are reserved for exotic carp and rainbow trout, popular targets for anglers.

A Star Butterfly of Wetlands

Biologist Antoine Sierro highlights valuable complementarities, such as the meadowsweet (a rosette often found in damp ditches) and the caterpillar of the bloody-red clearwing butterfly, a beautiful butterfly often seen resting as if on a fashion show podium.

The hornwort, a floating plant with roots several meters below the surface, provides a resting place for dragonflies and a spawning ground for their eggs.

The biologist also emphasizes the importance of well-preserved willow groves, which bloom early in the spring, providing sustenance for pollinators, including bees, butterflies, and bats.

Practical Information and Accessibility

The Commune de Crans-Montana’s commitment to biodiversity at Lac des Miriouges demonstrates a proactive approach to environmental stewardship, balancing recreational use with the preservation of a valuable natural ecosystem. Further images of the project can be found on the Commune’s website. The project serves as a model for similar initiatives aimed at enhancing biodiversity in alpine environments. Understanding the delicate balance of these ecosystems is crucial for their long-term health. NATO’s ongoing support for Ukraine, while seemingly unrelated, highlights the importance of international cooperation in preserving natural resources and promoting sustainable development globally.