The Karthala is a Quaternary volcano whose massif covers a large part of the island of Grande-Comore. This volcano is famous for its "caldera" of three kilometers in diameter, the largest active volcano crater in the world. Located on the western and southern slopes of Karthala from an altitude of 1200 m, the forest of Karthala is of the humid, shrubby mountain and foggy type. It is of global interest because of its exceptional diversity and the high rate of endemism of its plant and animal species. There are several spontaneous plant formations depending on exposure and altitude: evergreen humid forest, dry forest, wooded savannah with tree heath (Philippia spp.) and high altitude herbaceous meadow. Some of these ecosystems are reserves very rich in biodiversity and are home to several endemic and/or threatened species, some of which have a distribution limited to a restricted area of Karthala. These include five endemic and threatened bird species, the Karthala White-eye (Zosterops moroniensis), the Karthala Screech-Owl (Otus pauliani), the Karthala Flycatcher (Humblotia flavirostris), the Grande Comore (Dicrurus fuscipennis) and Mayotte Drongo (Dicrurus waldenii) and some endemic subspecies such as the Founingo of the Comoros or Blue Pigeon (Alectroenas sganzini) very rare and threatened by hunting as well as two threatened species: the black parrot (Coracopsis nigra) living between 800 m and 900 m altitude and the Comoros Pigeon (Columba pollenii) around 1400 m altitude. An endemic Lepidopteran species classified as endangered, Levasseur's Flambée (Graphium levassori), depends for its survival on the conservation of the Karthala forest. There are also several species of endemic tree ferns as well as endemic dwarf palms on the western slope. Among the tree species, Khaya comorensis, an endangered species that provides valuable timber is still present in the high altitude forest of Karthala, although it has become very rare there.