Common Name: Apitong

General Information

Dipterocarpus alatus is a medium-sized to fairly large evergreen tree with an umbrella-like crown, that can grow up to 40 metres tall, and exceptionally to 55 metres[, , ]. It has a tall, straight, cylindrical bole up to 150cm in diameter that can be branchless for up to 20 metres[, , ].
One of the most important timber species of southern Asia, it is extensively logged commercially, whilst the tree is also valued for its essential oil and oleoresin[, ]. It is often planted as a shade-giving avenue tree in Vietnam[].
The tree is threatened by habitat loss and is listed as 'Endangered' in the IUCN Red List of Threatened Species(2009)[].

Known Hazards

The dust of the wood causes boils[].

Botanical References

Range

E. Asia - Bangladesh, Myanmar, Thailand, Laos, Vietnam, Philippines.

Habitat

A canopy tree that occurs gregariously along river banks, and in mixed dipterocarp forest[]. Native to both evergreen and dry deciduous forests[].

Properties

Conservation Status	Endangered
Medicinal Rating
Other Uses Rating
Habit	Evergreen Tree
Height	30.00 m
Cultivation Status	Cultivated, Wild

Cultivation Details

A plant of the lowland tropics where it is found at elevations up to 500 metres[]. It grows best in areas where annual daytime temperatures are within the range 22 - 32°c, though it can tolerate 10 - 36°c[]. It can be killed at temperatures of 5°c[]. According to one report, it prefers a mean annual rainfall of 1,100 - 2,200mm, uniformly spread through the year[]. Another report says it has a preferred rainfall of 3,500 - 4,500mm, but can tolerate 3,000 - 5,200mm[].
The plant, especially when young, is very tolerant to shade and seedlings can survive under heavy shade for years[]. As trees grow older, they become more light-demanding[]. Found mainly on alluvial soils in the wild[]. Prefers a pH in the range 5 - 6.5, tolerating 4.5 - 7[].
Members of this genus generally only regenerate naturally in the shade of the forest. Seedlings and saplings can persist in dense forest shade for many years. In their first 2 years the young plants cannot tolerate major openings in the canopy, but after they are well established (about 120cm tall) the canopy can be opened up around them to speed up their growth[].
Annual production of oleoresin per tapped tree is between 23 and 31 litres[].
Trees have a thin bark and are very sensitive to damage by fire[].

Edible Uses

None known

Medicinal

The resin obtained from the trunk is disinfectant, laxative, diuretic, mildly stimulant. It is used in analgesic liniments and can be mixed with bee wax then used as an antiseptic in bandages on ulcerated wounds[].

The bark of the young tree, provided with 2 - 4 leaves, is believed to have medicinal virtues against rheumatism and diseases of the liver[].

Agroforestry Uses:

The tree is a rapid colonizer of alluvial soils along the sides of rivers - it is used as a pioneer in forestry planting schemes to restore wasteland and establish woodlands[, ].
The tree is used as a soil improver[]. The organic matter and NPK content of soils under the tree canopy have been shown to be higher than in soils further away from the tree[]. The tree is commonly intercropped with fruit trees[].

Other Uses

An oleoresin is obtained by tapping the tree[]. Yields are good, but the resin is rather thin[, ]. It is used by indigenous people for illumination and waterproofing baskets and boats[, ]. Industrially, it is used for (zinc-based) paint; printing ink industries; varnish for walls and furniture; and lacquer; it can even be used as a fuel in diesel engines[, ]. The resin is obtained by cutting a hole in the trunk near the base (about 90 - 150cm from the ground) and then dipping out the resin with a spoon as it collects there. To prolong the flow, a fire made from dead leaves or brushwood is made in the hole at intervals - this burns off the dried resinous film and allows the resin to flow again[, ].

An essential oil, called yaang oil, is obtained from the plant. It is used as a fixative in perfumes[].

The heartwood is reddish-gray; the sapwood white[]. The wood is rather hard, fine-grained, easy to saw and polish[]. It is not very durable in contact with the ground[]. One of the most important commercial timber species, next to teak, in Thailand[]. The wood is used for construction, railway sleepers, boats, pulp and a number of other purposes[, ]. Because of its resinous nature, it is less suitable for flooring or being exposed to the sun[].
The wood is used for fuel and to make charcoal[, ].

The tree is an important source of keruing timber. In addition to the information above, a general description of keruing timber is as follows:-
The heartwood is light red to red brown or purplish red brown; it is clearly demarcated from the 5 - 7cm wide band of sapwood. The texture is coarse; the grain straight or interlocked. The wood is moderately heavy to heavy; moderately hard; somewhat durable, being resistant to dry wood borers, fairly resistant to fungi but susceptible to termites. It seasons slowly, with a high risk of checking and distortion; once dry it is poorly stable to moderately stable in service. It has a high blunting effect on tools due to the presence of silica, stellite-tipped and tungsten carbide tools are recommended; some species are very resinous and can clog tools; there is occasional tearing on quartersawn wood; nailing and screwing are good, but require pre-boring; gluing is correct, but care is required because of the resin. A general construction timber, it is used in carpentry, panelling, joinery, floors, timber frame houses, boxes and crates, veneer etc[].

Propagation

Seed - it has a short viability and so should be sown as soon as it is ripe[]. No pre-treatment is required. Sow the seeds in a nursery seedbed, germination usually commences within 4 - 7 days at 25°c[, ]. Seedlings are ready to plant out when they are 30cm tall, which takes about 8 - 12 months[].
Seed storage behaviour is intermediate, the lowest safe moisture content is 17 %, no seeds survive further desiccation to 8 % moisture content[]. At 12 % moisture content, only 36 % germination occurred after 939 days hermetic storage at -18°c compared to 80 % viability before storage[].
Cuttings taken from coppice shoots produced after hedging rooted successfully with 44.5% rooting, indicating the potential for mass production of rooted cuttings from hedge orchards[].

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