The ecoregion covers the area above 1800 m elevation on (from north to south) Tsaratanana (2,876 m), Marojejy (2,133 m), Ankaratra (2,643 m), and Andringitra Massif (2,658 m). The ericoid thickets are surrounded at lower elevations by the Madagascar subhumid forests ecoregion. The total area of the ecoregion is . On Tsaratanana the thickets are higher up, starting above 2,500m. There are smaller areas of thicket in Anjanaharibe-Sud Reserve in the north and Andohahela National Park to the south.