The ecoregion covers the Central Range of the New Guinea Highlands, which extends along the spine of the island.

The isthmus' relatively low elevation (160 metres) separates the montane flora and fauna of the Central Range from those of the highlands on the Bird's Head and Bomberai peninsulas to the west.

The tree line is above 3000 metres elevation, above which are the high-elevation Central Range sub-alpine grasslands.

Lower montane forest zone is characterized by trees in the beech family (Fagaceae) including Castanopsis acuminatissima and species of Lithocarpus, elaeocarps (Elaeocarpaceae), and laurels (Lauraceae).

[8] A range of Australasian tropical marsupials are native to the ecoregion, including tree kangaroos.

Endemic marsupials include the speckled dasyure (Neophascogale lorentzii), great-tailed triok (Dactylopsila megalura), Stein's cuscus (Phalanger vestitus), Telefomin cuscus (Phalanger matanim), Weyland ringtail possum (Pseudocheirus caroli), and Pygmy ringtail possum (Pseudocheirus mayeri).

Near-endemic marsupial species include the red-bellied marsupial shrew (Phascolosorex doriae) black-tailed dasyure (Murexia melanurus), Macleay's dorcopsis (Dorcopsulus macleayi), mouse bandicoot (Microperoryctes murina), and Clara's echymipera (Echymipera clara).

Three murids - the large leptomys, eastern shrew mouse, and lesser small-toothed rat – are critically endangered.

Endemic bird species include the Papuan whipbird (Androphobus viridis), sooty shrike-thrush (Colluricincla umbrina), Snow Mountain munia (Lonchura montana), black-breasted munia (Lonchura teerinki), Archbold's bowerbird (Archboldia papuensis), short-tailed paradigalla (Paradigalla brevicauda), and King-of-Saxony bird-of-paradise (Pteridophora alberti).