Above 1000 meters elevation, the dipterocarps that characterize the lowland forests become fewer, and trees in the beech family (Fagaceae) become predominant, including evergreen oaks (Quercus) and species of Lithocarpus and Castanopsis.

Common trees include species of Dacrydium, Daphniphyllum, Eurya, Ficus, Gordonia, Ilex, Leptospermum, Lindera, Lithocarpus, Melicope, Podocarpus, Prunus, Quercus, Syzygium, Schima, Ternstroemia, and Tristaniopsis, and Pterophylla fraxinea.

[3] The ecoregion home to several large and endangered mammal species – Asian elephant (Elephas maximus), gaur (Bos gaurus), tiger (Panthera tigris), sun bear (Helarctos malayanus), Malayan tapir (Tapirus indicus), clouded leopard (Neofelis nebulosa), and siamang (Symphalangus syndactylus).

[4] The Sumatran rhinoceros (Dicerorhinus sumatrensis) once inhabited the forests, but Malaysia's last rhinoceroses died in 2019, and the species' few remaining members survive only in Sumatra.

[5] The ecoregion is home to over 250 species of birds, including the endangered Malayan crested argus (Rheinardia nigrescens), and the threatened endemic mountain peacock-pheasant (Polyplectron inopinatum).