Kasijy Special Reserve is located 20 km north-west of Bemonto. The site comprises two forested outcrops of karst: the Kasijy massif and the small Analamajera massif. Three rivers delimit the site: the Andranomaitso river in the north, the Mahavavy river in the east and the Mahiarere river in the south. In the west, the site is bounded by a line from the Mahavavy river to the source of the Andranomaitso. In the north, the forest is dense, semi-deciduous and dry, with trees of Adansonia, Cedrelopsis and Hildegardia dominating. An area of savanna, with some woody species, is located in the southern part.
See Box and Tables 2 and 3 for key species. Fifty-four species are known from the site, of which 27 are endemic to Madagascar. Species of global conservation concern include Accipiter henstii and Philepitta schlegeli.