Local names:
Filipino (lanutan-bagyo,anauan), Indonesian (ramin), Malay (merang,gaharu buaya)
Gonystylus bancanus is a tree to 40-45 m tall with a straight, cylindrical bole; branchless to 21 m and a diameter of up to 120 cm. The tree is sometimes slightly fluted at the base with many knee-roots (pneumatophores). The bark surface is often cracked and shows greyish to red brown colour while inner bark is yellow and fibrous. Leaves elliptical, oblong-oblanceolate or obovate, 4-14.5 cm x 2-7 cm, broadly cuneate to rounded at the base, suddenly narrowing into a point; petiole 8-18 mm long. Inflorescence up to 9 cm long with short, adpressed hairs. Flowers with 8-14 mm long pedicels and 13-20, narrowly lanceolate, glabrous petals. Fruit sub-globose, up to 4.5 cm long, with 3-4 valves, minutely rough but not rugose, 1-3 seeds per fruit. Seeds compressed ovoid, black, 28 x 22 x 6 mm, partly enclosed in a thin aril.
Ecology
G. bancanus is a gregarious, often dominant tree of lowland freshwater swamp and peat-swamp forest. It is a lowland species growing in freshwater swamp and coastal peat-swamp forest including peripheral mixed swamp forest and Shorea albida forest, occasionally forming pure stands. In these forests it is associated with Calophyllum kunstlerii, Xylopia malacensis, Mezzetia parvifolia, and Shorea pauciflora as a top layer of the vegetation. Large areas of peat swamp forest have been cleared for agriculture, with extensive development of oil palm and pineapple plantations.
Native range
Brunei, Fiji, Indonesia, Malaysia, Philippines, Solomon Islands
Tree management
G. bancanus tolerates waterlogging and self-prunes. Since seedlings and saplings require shade, the planting should be in the strip or line planting system in logged-over or secondary peat-swamp forest, with spacing of 5 m by 5 m in logged-over forest and 3 m by 1 m in secondary forest. After 2-3 years the shade can be gradually removed to stimulate growth. First thinning is carried out at an age of 5 years in a planted forest, and from then on at intervals of 3 years up to the age of 20 years, and subsequently at intervals of 5 years up to the felling age. In Indonesia, natural ramin peat-swamp forest is managed under the Indonesian selective felling and planting system, with a diameter limit of 35 cm and a cutting cycle of 35 years. At least 25 healthy trees per ha of over 15 cm diameter should be left as core trees. In Sarawak large areas of logged-over mixed peat-swamp forest are regularly treated to stimulate regeneration and growth of ramin.
The fruits open and release the seeds when ripe. The freshly fallen seeds are collected from the ground. As access to the swamp forest where G. bancanus grows is often very difficult, seed collection is generally carried out only around log slide tracks. The freshly collected seeds have a moisture content of about 40-45%, and during transportation from collection sites, the seeds have to be protected from excessive loss of moisture, e.g. by placing them under shade in moist gunny sacks. At the processing site, the seeds are washed and air-dried on the surface. The seeds storage behaviour is recalcitrant. The seeds can be stored temporarily with moist sawdust in sealed polyethylene bags in an air-conditioned room (18° C). After longer periods of storage, the seeds begin to germinate. There are 250-300 seeds/kg.
G. bancanus is a gregarious, often dominant tree of lowland freshwater swamp and peat-swamp forest. It is a lowland species growing in freshwater swamp and coastal peat-swamp forest including peripheral mixed swamp forest and Shorea albida forest, occasionally forming pure stands. In these forests it is associated with Calophyllum kunstlerii, Xylopia malacensis, Mezzetia parvifolia, and Shorea pauciflora as a top layer of the vegetation. Large areas of peat swamp forest have been cleared for agriculture, with extensive development of oil palm and pineapple plantations.
G. bancanus can be planted using wildings, nursery raised seedlings and cuttings. The seeds are soaked in water for 24 hours prior to sowing in order to enhance germination. They are sown in sand or a mixture of sawdust and soil (2:1) in shady conditions. The seedbed should be covered with transparent material (e.g. plastic) to avoid excessive moisture loss. Germination begins about 5 days and is completed after about 30 days. In the nursery the seedlings should be placed under shade. The seedlings are ready for planting after 8-11 months when they are about 20 cm tall.
Poison: The pounded fruits are sometimes used as fish poison.
In Kalimantan, seedlings are used in enrichment planting.
The fruits and leaves provide food for wild animals such as swamp monkeys
Timber: The timber has white to light yellowish-white heartwood, moderately fine with even texture, and density of 0.54-0.75 g/cm3 (moisture content 15%). It is very suitable for veneer and plywood, and highly valued for light construction including door and window frames, moulding, skirting, ceilings and partitions. Among other things it is used for decorative cabinets, furniture, interior decoration, wall panelling, light flooring, toys, turnery, broom handles and other non-impact handles, venetian blind slats, dowels, rulers, picture frames, and drawing boards. Populations and habitats of the species have decreased sharply due to over exploitation.
Medicine: A decoction of the roots is administered after childbirth as a protective medicine.