Rainfall is highly seasonal, falling mostly with the summer monsoon from the Bay of Bengal and South China Sea between April and October.

Several kinds of trees from Dipterocarpaceae can also be found in this area, for example Parashorea chinensis, Dipterocarpus retusus and Hopea mollissima.

[1] On Fan Si Pan in northern Vietnam, a distinct fir-hemlock forest grows above 2,000 m (6,600 ft) elevation, and is found nowhere else in Southeast Asia.

The firs and hemlocks are accompanied by broadleaf trees of families Aceraceae, Hippocastanaceae, Fagaceae, Magnoliaceae, and Lauraceae, and conifers of Cupressaceae, Podocarpaceae, and Taxaceae.

[1] Forests growing on limestone substrates have a distinct composition, with the trees Tetrameles nudiflora, Antiaris toxicaria, Celtis timorensis, C. philippensis, Cleistanthus sumatranus, Garuga floribunda, Pterospermum menglunense, Ulmus lanceifolia, and Xantolis stenosepala.

They include the Asian elephant (Elephas maxiumus), tiger (Panthera tigris), Asian black bear (Ursus thibetanus), gaur (Bos gaurus), mainland serow (Capricornis sumatraensis milneedwardsii), banteng (Bos javanicus), clouded leopard (Pardofelis nebulosa), red panda (Ailurus fulgens), particoloured flying squirrel (Hylopetes alboniger), pygmy loris (Nycticebus pygmaeus), northern pig-tailed macaque (Macaca leonina), Assam macaque (Macaca assamensis), stump-tailed macaque (Macaca arctoides), dhole (Cuon alpinus), smooth-coated otter (Lutrogale perspicillata), back-striped weasel (Mustela strigidorsa), and inornate squirrel (Callosciurus inornatus).

Fea's muntjac (Muntiacus feae), Anderson's squirrel (Callosciurus quinquestriatus), Owston's palm civet (Chrotogale owstoni), the red-throated squirrel (Dremomys gularis), northern white-cheeked gibbon (Hylobates leucogenys), and Chaotung vole (Eothenomys olitor) are near-endemic mammals, native to the ecoregion and one or more adjacent ecoregions.