There are several forest types present. Lowland evergreen forests grow in the narrow coastal plain between the mountains and the Gulf of Thailand. These forests have mostly disappeared. Dwarf rain forests occupy waterlogged areas in the southern slopes of the mountains, with the tree canopy not exceeding 12 meters in height. The conifers Dacrydium elatum and Podocarpus neriifolius are the predominant trees, with scattered Nageia fleuryi and Dacrycarpus imbricatus. Montane forests cover large parts of the ecoregion above 700 metres elevation. Trees form a dense canopy up to 30 meters high. Trees in the beech family are prominent, including Lithocarpus cambodiensis, Lithocarpus guinieri, Lithocarpus farinulentus, Lithocarpus harmandii, and Castanopsis cambodiana. Other prominent trees are in the laurel family, including species of Cinnamomum and Litsea, and the myrtle family, including species of Syzygium and Tristaniopsis. The montane forests are also home to diverse palms, understory shrubs, tree ferns, and epiphytes, including many orchids. Dwarf montane forests grow in acidic sandstone-derived soils in the southern Elephant Mountains, where the conifers Dacrydium elatum, Dacrycarpus imbricatus, and other trees form a low canopy 5–10 meters high. Forests dominated by Pinus merkusii are found on the Kirirom Plateau in the Elephant Mountains. The Cardamom Mountains rain forests are part of the regional Indo-Burma Hotspot, a biodiversity hotspot of global importance with a large biological variation, and home to many rare, threatened and endemic species. The Cardamom Mountains rain forests is home to many endemic species. Because of its remote location, very small human population, and difficult terrain, most of these forests remain relatively unexplored by scientists.
The Cardamom Mountains rain forest is one of the last intact rain forests left in Southeast Asia. It is also one of the most species-rich areas in the world, including many rare, threatened and endemic species. After the Cambodian peace agreements and normalization in the 1990s, large parts of the Cardamom Mountains, and adjoining lowlands of the ecoregion, were designated as protected areas, mostly national parks and wildlife sanctuaries. With the establishment of the large Southern Cardamom National Park in May 2016, nearly all of the mountain range is now under some form of high level protection. ;Thailand
Even though most of the ecoregion is under protection, it is under pressure from many degrading and destructive activities. This includes construction and infrastructure projects, mining, clearing for plantations, sand pumping, illegal loggings, hunting and poaching. The protection laws has been poorly enforced and the Cambodian government has accepted and even encouraged destructive activities throughout, including national park areas. The establishment of the Southern Cardamom National Park in 2016, may signal a change and improvement of the protection enforcement on ground level, as international organisations has stepped in with financing and practical help with park ranger tasks in an administrative collaboration with the Cambodian government. Also, a number of planned construction, plantation and mining projects has been put on hold.
Ecoregion designation
The WWF's numerical designation for the ecoregion is IM0106.
