Tropical evergreens grow in all areas of Thailand, though they are found mostly in the southern and eastern areas of the country. Locations such as Rayong, Chanthaburi and Trad feature heavy rainfall and high moisture levels in the air and soil that contribute to the growth of the tropical evergreens. In other parts of the country, the tropical evergreens grow in areas that contain high moisture levels, such as near rivers and streams or in valleys where moisture drains from mountains and pools.
An evergreen forest can house hundreds of different types of flowers and trees that grow right next to one another; none of these plants will lose their leaves, regardless of the season. In addition to the huge trees often associated with a tropical forest, smaller plants like bamboo and wicker can also thrive in these tropical evergreen areas.
Coniferous evergreen forest grows between altitudes of 700 meters (2,296 feet) above sea level and 1,00 meters (3,280 feet) above sea level. These trees are found mostly in the northern areas of Thailand; while they can be scattered in the central and northeast regions, you will not find coniferous forests south of Chumporn.
The acidic soil found at this elevation and in these areas means that the forest is not as dense as the tropical forest; fewer plants grow here. Coniferous forests consist mostly of pine trees, with a few smaller flowers or plants scattered among the pines.
Hill evergreen forests grow only in areas of high altitude, generally in areas that are at least 1,000 meters (3,280 feet) above sea level. At these higher altitudes the temperature is cooler.
Unlike the tropical forests, fewer large trees grow in regions such as Phu Luang and Phu Kradung. Instead, hill evergreen forests consist mostly of shrubs and pine trees, with smaller plants like orchids or lilacs. Some plants, like a variety of mosses, will grow onto the larger trees.
Mangrove forests can be found in eastern Thailand, most notably at the mouths of major rivers. These forests also grow in other areas of the country near the mouths of rivers.
The floors of mangrove forests are exceptionally dense, with roots from trees overlapping in many areas. Many of the smaller trees in this type of forest, including the kongklang and prasak trees, are used to make charcoal and firewood. A variety of sea grasses also grow here.
While tropical, coniferous, hill and mangrove forests are the primary source of evergreens in Thailand, there are a few smaller types of forests that grow in very specific areas.
Beach forests grow in areas where the sea washes onto the land. Weeds and vines choke the forest floor, and sea pines and other such woody trees grow in these small forests.
Swamp forests grow in areas where freshwater floods the land. Soils here tend to drain poorly so the water sits in pools for long periods of time; these forests are most commonly found in the south. Swamp forests generally contain just one type of tree: for instance, a samet swamp. Many of these swamp forests will also feature vines that grow along the floor and up the trees.
