The SIC Les Arnauds – Four Sisters’ End extends over a surface of 1031 hectares which, from the Second World War became French territory. It comprises a wide alpine area with predominance of rocky habitats such as limestone walls and screes. Hosts a specialized vegetation, characterized by the presence of Berardia subacaulis, endemita of tertiary origin, and the rare Valerian saliunca. At lower altitudes and in the valley of Rho, the slopes have softer shapes and are better suited to the development of the vegetation. At the level of forest there are larch-cembrete, but also pine mountain pine (Pinus uncinata) and Scots pine (Pinus sylvestris); on the land a dissodati time and cultured meet flaps of maple-lime-Frassineti and brushwood pioneer of invasion to hazel and Aspen.
In the nest site about 25 species of birds, largely passerines; among the elements of Community interest is declared the stable presence of the golden eagle (Aquila chrysaetos) and of her minor (Lanius collurio). Among the mammals we can observe some typical ungulates of the Alpine area: the chamois (Rupicapra rupicapra), especially in the rocky areas more inaccessible, deer (Cervus elaphus) and the roe deer (Capreolus capreolus), in woody band and its margin. Of importance is the frequentation of the site by the wolf (Canis lupus). There are also numerous lepidopteran pests considered xerotermofili wrecks and Mediterranean, in addition to the species Parnassius phoebus and Maculinea arion.