Koh Chang’s Natural Erosion and Flooding Control is Dipterocarpus Alatus
Dipterocarpus alatus occurs abundantly along the river banks of Koh Chang which is op to 500 meters altitude and where it is a rapid colonizer of alluvial soils. This tree species is a tropical forest tree of dense evergreen or mixed dense forests common in Thailand, Cambodia, Laos, Malaysia, Philippines and Vietnam. It is commonly known in English as hairy-leafed apitong and yang-na in Thai. This tree is an endangered species in its natural habitat.
Dipterocarpus alatus is a medium-sized to fairly large tree of up to 60 meters tall. Its trunk is straight, cylindrical, and measuring up to 150 centimeters in diameter. The leaves are narrowly ovate-ovate to elliptical-oblong. It has bi-sexual flowers with large petals which are oblong to narrowly oblong and are strongly contorted, loosely cohering at base on falling, and cream-white with a prominent pink, red or purple stripe down the center. Its fruit is a nut that is surrounded by the calyx, comparatively large; fruit calyx tube glabrous, with 5 wings, to 8 millimeters broad, 2 larger fruit calyx lobes up to 14 centimeters by 3 centimeters, 3 shorter ones up to 12 millimeters by 14 millimeters. The wood of Dipterocarpus alatus is much valued in construction and cabinetwork. It is considered as one of the most important timber species next to teak in Thailand.
The extracted oleoresin is used by indigenous people for illumination and waterproofing baskets and boats. It is exported to other countries and it is used for paint, varnish and lacquer. When mixed with beeswax, it is used in bandages for ulcerated wounds. Annual production of oleoresin per tapped tree is between 23 and 31 liters. The bark of young trees is also used in traditional medicine, taken against rheumatism and diseases of the liver, and to stimulate appetite in cattle. Its oil is used as a fixative in perfumes.