Background Réunion is classified as one of the world’s top 25 hotspots for land biodiversity. The semi-xerophilous (semi-dry, drought loving) habitats represent some of the most remarkable habitats of the island. Now completely disappeared from other areas of the Mascareignes, today these habitats are estimated to cover only 1% of their original area (56 800 ha) on Reunion. These last relics are subject to significant natural and man-made threats and are present today only in degraded form and in inaccessible areas (gullies and cliffs). Objectives The Massif de la Montagne, with approximately 255 ha of more or less sub-standard semi-xerophilous habitats, constitutes one of the final incidences of this type of vegetation on Reunion. With a view to assuring the ecological viability of these habitats, this LIFE+ Biodiversity project plans to: Restore and preserve approximately 30 ha of relic-type habitat, undergoing high anthropogenic and natural pressures, in order to ensure its ecological functionality; Restore 9 ha of unique semi-xerophilous habitats on Reunion to its original condition. This reconstituted area located on a small plateau between two gullies and resting on existing relic areas, will also createthe possibility of restoring an ecological corridor; Combat the erosion of biodiversity by preserving the unique species sheltered by these habitats through the reinforcement of rare vegetation and protected species including some that face extinction, while avoiding the risk of genetic pollution. The project expects to reinforce the populations of at least 22 rare and endangered species; Define innovative protocols for the restoration and the reconstitution of semi-xerophilous habitats on Reunion that can be transferred to similar projects in the Southwest Indian Ocean area; Acquire detailed knowledge of the semi-xerophilous habitats; Exchange, share, raise awareness and communicate the importance of biodiversity and especially the conservation of this type of habitat. The project aims to create lasting networks for technical and scientific exchange for people working to preserve and restore semi-xerophilous habitats.