Like any typical tropical rainforest, the main forest types within DTC include the lowland mixed dipterscamp rainforest which stratifies into three main layers with the top one rising to 45m in height. Underneath, on the forest floor is a layer of leaf-litter in various stages of decomposition.
Besides the Lowland Dipterocarp Forest, there are the Hill Dipterocarp Forest, the thpper Hill Dipterocarp Forest and the Lower Montane Forest. The main tree species are from the Dipterocarpaceae family dominated by important commercial species of Shorea, Diperocarpus, Dryobalanops and Neobalanocarpus. Members of the non-Dipterocarpaceae family are mainly from Leguminosae, Sapotaceae, Burseraceae, Anacardiaceae and Myristicaceae.
Among the main tree species in the DTC forest area are:
- Dipterocarpus sarawakensis (Keruing Sarawak) and Vatica sp. nov.
This endangered species was initially thought to be extinct and only present uniquely in Sarawak (hence the name), until the discovery of a group of 53 trees of this species in Jerangau Forest Reserve at the end of 2004. They were found in the sensitive habitat of Kerangas / Peat Swamp forests with natural regeneration on the ground.
- Kapur (Dryobalanops aromatica) tree;
Dryobalanop aromatica is a tree species in the Dipterocarpaceae family. It is a gregarious species and often forms a pure crop of tall 'emergent' trees, up to 65 m or even 75 m tall, with coalescing crowns over small areas found in mixed dipterocarp forests on deep humic yellow sandy soils. The leaf of Dryobalanops aromatica is very coriaceous and there is in consequence more leaf litter in Kapur forests than in other lowland dipterocarp forest types.
- Meranti-keruing (Shorea spp.- Dipterocarpus spp.) Dipterocarp forest;
Dipterocarpus is a genus of flowering plants from the family Dipterocarpaceae. The genus has about 70 species, distibuted in Southeast Asia. It is an important component of dipterocarp forests. The genus is of considerable importance as timber trees, sold under the trade name Keruing.On the other hand, Meranti is a species of Shorea, which is a genus of about 196 tree species of the family Dipterocarpaceae. Many economically important timber trees belong to Shorea. Besides Meranti, they are also sold under various other trade names including "Lauan" (or "Luan"), "Seraya", "Balau", and "Bangkirai".
- Chengal (Neobalanocarpus heimii) tree
This very high value species is endemic to Peninsular Malaysia, often found in specific forest types in Dungun Timber Complex. The longest Chengal tree in the world was discovered in DTC in 1999 by the Terengganu Forestry Department’s Omar Mohamad. The tree, measuring 16.5m tall with a 16.75m circumference, required 13 people to “hug” its trunk.
Chengal wood is highly resistant to decay when in ground contact or in persistently damp or poorly ventilated situations. The wood is used in heavy construction such as boat building, railway sleepers, wharf and bridge construction, poles and piles. It is also has a high potential to be propagated and grown in plantations.