About this place
Réserve naturelle nationale du ravin de Valbois is one of the most valuable nature reserves in the Bourgogne-Franche-Comté region, located in the Doubs department around 25 km south of Besançon. The reserve spans the communes of Cléron and Chassagne-Saint-Denis, within the protected Loue and Lison valleys covered by the Natura 2000 network.
What is the ravin de Valbois?
Established in 1983, the reserve covers 235 hectares of a Jurassian ravine cut into the edge of the Loue river valley. It stretches for about 3 km, with elevations ranging from 330 to 550 metres above sea level. This creates, within a relatively compact area, a striking range of environments — from dry, sun-exposed slopes to cool, damp valley floors.
What does the landscape look like?
The reserve's defining feature is its steep, rocky cliffs of Rauracian limestone dropping toward the valley floor. At their base lie impermeable Oxfordian clays, while the slopes are covered with rock scree typical of Jura landscapes. This mosaic of rock, soil and sun exposure explains why such a small area supports such a rich variety of life.
Why is this site so important for nature?
More than 6,500 plant and animal species have been recorded within the reserve — an impressive figure for a site of this size. The variety of microclimates, from warm, dry grasslands on exposed slopes to shaded, humid stretches at the bottom of the ravine, allows species with very different habitat needs to coexist. The cliffs and scree slopes provide important shelter and nesting sites, while old-growth stands and hard-to-reach forest patches help shield the most sensitive parts of the ecosystem from human pressure.
Who manages the reserve?
Since 1 January 2014, the reserve has been managed by the Conservatoire d'espaces naturels de Franche-Comté, the organisation responsible for its ecological protection and monitoring, as well as for maintaining the visitor infrastructure that allows the site to be explored without damaging the environment.
How can you visit the reserve?
A marked walking trail runs through the reserve as a loop of roughly 5 km with about 130 metres of elevation gain, typically taking 2 to 3 hours to complete. The route first leads to a medieval site before descending into the ravine, at the heart of the nature reserve. Combining a historical waypoint with the natural landscape gives the hike an extra cultural dimension beyond the scenery itself.
Frequently asked questions
Where exactly is the reserve located? In the Doubs department, across the communes of Cléron and Chassagne-Saint-Denis, about 25 km south of Besançon, within the Loue and Lison valleys.
How large is the reserve and when was it created? The reserve covers 235 hectares and was established in 1983.
How long is the hiking trail through the reserve? The loop trail is about 5 km long with 130 metres of elevation gain, taking roughly 2 to 3 hours to walk.
What can you see along the way? The trail passes a medieval site before entering the rocky ravine, with its characteristic limestone cliffs and scree slopes.
Who looks after the reserve? Since 2014, it has been managed by the Conservatoire d'espaces naturels de Franche-Comté.
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