Réserve naturelle régionale du coteau et plateau de Tessé: A Protected Limestone Landscape

The Réserve naturelle régionale du coteau et plateau de Tessé was officially classified on 14 December 2009 by the regional council of Pays de la Loire. The classification was established for an initial renewable period of six years and designated the reserve as RNR214 within the French regional nature reserve system.

The site's ecological value, however, predates its formal protection. The shallow, rocky limestone soils of the plateau have historically restricted cultivation and instead encouraged pastoral use, and the presence of a nearby former quarry reflects long-standing human awareness of the limestone substrate. The creation of the reserve by the Conservatoire d'espaces naturels de la Sarthe formalized the protection of a habitat that had already been maintained in a semi-natural state by traditional land use.

The landscape of the reserve is shaped by its calcareous geology and its position along the Rutin valley. The terrain consists of a single parcel combining a plateau and a coteau, or limestone slope, at an altitude of about 140 metres. The underlying oolithic limestone of the upper Bajocian stage, deposited roughly 170 million years ago, outcrops across the slope, and was once exploited in a nearby quarry.

The thin, rocky soils derived from this limestone have prevented agricultural intensification and helped preserve a pastoral landscape of open calcareous grassland. Junipers, shrubs such as Bois de Sainte-Lucie, and herbaceous plants like Globulaire commune and Pulsatille vulgaire give the coteau a character typical of dry limestone habitats. The combination of plateau and slope creates a compact but varied micro-topography within a very small area, making the site especially valuable for the dry-habitat species it supports.

Calcareous grassland is the defining ecological feature of the reserve. The exposed oolithic limestone limits soil development and creates the dry, nutrient-poor conditions that support a specialised flora. The reserve hosts more than 200 vascular plant species, including three regionally protected plants: Globulaire commune, Pulsatille vulgaire, and Petit pigamon. A further 24 species appear on the regional red list.

Beyond these highlights, the vegetation includes characteristic calcareous grassland species such as Bois de Sainte-Lucie, Genévrier commun, Céraiste des champs, and Polygale du calcaire. Juniper, in particular, contributes shrubby structure to the otherwise open landscape. Together, these elements create a dry, sun-exposed habitat community that contrasts with the surrounding woodland and agricultural land in the Rutin valley.

The reserve is officially a small, habitat-focused site designated under IUCN Category IV, a classification that emphasises active management of specific habitats and species rather than wilderness preservation.

The fauna documented at the reserve amounts to around 92 recorded species, overwhelmingly composed of insects. Orthopterans, or grasshoppers and related insects, are particularly well represented, with species recorded including the Gomphocère roux and the Criquet de la palène. The reserve's open, sun-exposed calcareous slopes provide ideal conditions for these warmth-loving invertebrates, which depend on the short grassland structure maintained by pastoral activity.

Butterflies are another highlight of the site's biodiversity, with 39 species recorded. Notable species present include the Zygène transalpine, the Azuré des cytises, the Argus bleu-nacré, the Argus bleu céleste, the Virgule, and the Mélitée des scabieuses. Together, these insects illustrate how a small calcareous site can sustain a rich and specialised invertebrate community.

The reserve was created primarily to protect a fragment of calcareous grassland habitat in the Sarthe. By safeguarding the outcropping limestone, the associated dry soils, and the open pasture vegetation, it preserves conditions that support a high concentration of regionally protected plants and rare invertebrates within a very small footprint.

As a Category IV protected area under the IUCN framework, the reserve is managed with a focus on habitat and species conservation rather than strict wilderness preservation. The Conservatoire d'espaces naturels de la Sarthe oversees its management, ensuring that the traditional pastoral dynamic that maintains the grassland continues and that the botanical and entomological values documented for the site are preserved over successive six-year classification cycles.

The cultural context of the reserve is closely tied to the long-standing interaction between people and the limestone landscape of the Sarthe. Outcropping oolithic limestone once supported a local quarry, and the thin soils of the coteau and plateau have historically made cultivation impractical, encouraging pastoral land use.

This pastoral tradition has shaped the reserve's present-day character, since it is the combination of rocky terrain and grazing that has maintained the open calcareous grassland on which the reserve's biodiversity depends. The site thus reflects a regional heritage of working with, rather than against, the limitations of limestone terrain in northwestern France.

The Réserve naturelle régionale du coteau et plateau de Tessé stands out as a compact yet species-rich calcareous habitat in the Sarthe. Five and a half hectares of plateau and slope protect more than 200 plant species, including three regionally protected plants and 24 red-list species, alongside 39 butterfly species and a notable community of orthopterans.

The reserve's tight focus on a single habitat type, dry limestone grassland, makes it an unusually concentrated example of calcareous habitat conservation in the Pays de la Loire. Its small size and accessible location, combined with its IUCN Category IV status and management by the Conservatoire d'espaces naturels de la Sarthe, make it a useful local reference site for understanding how small protected areas can play important roles in regional biodiversity conservation.

Calcareous grasslands such as this one are at their most vivid in late spring and summer, when the flowering of characteristic limestone plants such as Globulaire commune, Pulsatille vulgaire, and Polygale du calcaire brings colour to the slope. Warm, sunny conditions during this period also support peak activity among butterflies and orthopterans, making the warmer months the most rewarding time to observe the site's botanical and entomological richness. Visitors should note that public access is permitted under the reserve's regulations, and visits should respect the delicate grassland habitat.