The Eastern Arc Forests is a montane tropical moist forest ecoregion of eastern Africa. The ecoregion comprises several separate areas above 1000 meters in the mountains of Kenya, and (mostly) Tanzania.
The Eastern Arc forests extend across a total of 9,200 square miles of mountainous landscape from the Taita Hills on the border of the two countries, through eastern Tanzania to the Udzungwa Mountains and Mount Rungwe. The ecoregion includes the Taita Hills, the North and South Pare Mountains, the East and West Usambara Mountains, the North and South Nguru Mountains, the Ukaguru, the Uluguru, the Rubeho, and the Udzungwas, as well as Mahenge to the south of the Udzungwas, Malundwe Hill in Mikumi, and the Uvidundwa Mountains north of the Udzungwas.
These hills are home to many endemic species including over 800 plants, and are the original homeland of the African violet (Saintpaulia) and the Busy Lizzie (Impatiens).
The ecoregion is rich in wildlife with many endemic species of birds, and some mammals, while endemic amphibians include five species of reed frogs (Hyperolius), two species of forest treefrogs (Leptopelis), five tree toads (Nectophrynoides), four species of Microhylidae, and five Caeciliidae. Endemic reptiles include ten species of chameleons (seven Chamaeleo and three Rhampholeon), three worm snakes (Typhlops), and six Colubridae snakes. Invertebrates show very high levels of endemism too. Furthermore, study of the wildlife on these isolated hills is important for research into evolutionary pathways.