Plateau de la Leysse

Plateau de la Leysse. A prominent limestone plateau located in the Savoie department of the French Alps, forming a significant part of the Bauges Massif. This elevated karstic landscape is characterized by its vast alpine pastures, deep gorges, and complex hydrological systems, notably the resurgence of the River Leysse. The plateau serves as a crucial watershed and a haven for diverse flora and fauna, with its human history marked by pastoralism and its modern management focused on balancing conservation with traditional uses.

Geography

Situated within the Regional Natural Park of the Bauges, the Plateau de la Leysse lies to the east of the city of Chambéry and north of the Lac du Bourget. The terrain is dominated by high-altitude pastures, known locally as *alpages*, and is deeply incised by the gorges of the River Leysse, which originates from a major resurgence, the Source of the Leysse, at the base of the plateau. Key surrounding peaks include the Mont Revard and the Dent de Cons, which frame the plateau's topography. The area drains into the Leysse valley, ultimately feeding the Lac du Bourget and the Rhône river system. Notable adjacent communes include Les Déserts, Saint-Jean-d'Arvey, and La Féclaz, a popular ski station.

Geology

The plateau is a classic example of a karst landscape formed from Urgonian limestone, a thick, massive Cretaceous formation prevalent throughout the Bauges Massif. This soluble rock has been extensively shaped by water, creating a network of dolines, lapiaz, and underground drainage systems. The most significant geological feature is the active karstic system of the River Leysse, where water infiltrates the plateau's surface and re-emerges at the powerful Source of the Leysse. This hydrology is studied in the context of the broader alpine geology of the Western Alps, with parallels to other karst regions like the Vercors Massif and the Chartreuse Mountains. The plateau's structure influences local aquifers and presents challenges for hydrological mapping.

Ecology

The Plateau de la Leysse supports a mosaic of alpine ecosystems, from flower-rich hay meadows to subalpine forests and rocky outcrops. It is part of the Natura 2000 network, designated for its important habitats and species. The pastures are maintained by traditional grazing of Tarantaise cattle and Savoyard sheep, supporting species like the Apollo butterfly and the black grouse. Forested slopes are dominated by European beech and Norway spruce, providing habitat for roe deer, chamois, and birds such as the capercaillie. The area is also known for its diverse flora, including several orchid species and alpine plants like the gentian. The karst springs host specialized aquatic invertebrates.

Human history

Human use of the plateau dates back millennia, with evidence of pastoral activity from the Neolithic period onwards. Historically, the area was integral to the seasonal transhumance practices of the Savoy region, with chalets and *alpages* managed by communities from surrounding valleys. The plateau lay within the historical territories of the Duchy of Savoy and later the Kingdom of Sardinia before the annexation of Savoy to France in 1860 following the Treaty of Turin. The construction of roads and the development of La Féclaz for winter sports in the 20th century marked a shift, though traditional farming persists. The area has also been a site for hydrological and speleological research since the 19th century.

Conservation and management

The primary management framework for the plateau is the Regional Natural Park of the Bauges, established in 1995, which coordinates efforts to protect the landscape while supporting sustainable agriculture and tourism. Key conservation instruments include the Natura 2000 directives and the park's own charter, which regulates activities like forestry, grazing, and recreational development. Partners such as the French Office for Biodiversity and the Conservatoire d'espaces naturels de Savoie work on specific projects, including habitat restoration for grassland birds and managing public access to sensitive karst areas. Challenges include balancing the pressures from the ski resorts of La Féclaz and Le Revard with ecological integrity, protecting water quality from the Source of the Leysse, and maintaining viable agricultural practices against economic pressures.

Category:Plateaus of France Category:Landforms of Savoie Category:Bauges Massif Category:Karst formations of the Alps