The Chastreix-Sancy national nature reserve is located on the Western/Southwest flanks of the Puy de Sancy (photo). Thanks to its altitudinal amplitude and the variety of its exposures and substrates, the reserve is home to forty-five different natural environments. For example, the ridge areas contain sub-alpine cliff plant groups, as well as grasslands which are very rare in Auvergne. In summer, these grasslands are widely used by livestock farmers as pastures for their herds.