This 28,255 hectares (69,820 acres) reserve is within the commune of Begogo, in Anosy Region and 55 kilometres (34 mi) east of Betroka.

The Kalambatritra massif is a series of undulating hills and steep summits and is part of the Antaivondro-Kalambatritra mountain chain.

[2] The humid, evergreen forest is relatively undisturbed and divided into blocks with savannahs of the coarse grass (Aristida imperata) inbetween.

Among the 699 species of plants so far recorded on the reserve, two families are endemic; the Torricelliaceae, including Melanophylla alnifolia and the Sarcolaenaceae including Leptolaena pauciflora, which, according to the International Union for Conservation of Nature (IUCN) is an endangered species on the IUCN Red List.

Growing rice and cutting wood for construction and cooking are the main threats to the area.