Bruguiera cylindrica (PROSEA)

Plant Resources of South-East Asia Introduction

List of species

Bruguiera cylindrica (L.) Blume

Protologue: Enum. Pl. Javae 1: 93 (1827).

Family: Rhizophoraceae

Chromosome number: 2n= unknown

Synonyms

• Rhizophora cylindrica L. (1753),
• Rhizophora caryophylloides Burm.f. (1768),
• Bruguiera caryophylloides (Burm.f.) Blume (1827).

Vernacular names

• Black mangrove (En)
• Indonesia: lindur (Madura), tanjang sukun (Java)
• Malaysia: berus (general), bakau belukap, berus ngayong (Sarawak)
• Philippines: pototan lalaki (general), bakáuan (Tagalog), kalapínai (Ilokano)
• Burma (Myanmar): byu, saung
• Thailand: thua-daeng (Chanthaburi), thua-khao (Ranong, Krabi), rui (Phetchaburi)
• Vietnam: vẹt trụ, vẹt khang

Origin and geographic distribution

Bruguiera cylindrica occurs naturally in mangroves from India and Sri Lanka throughout South-East Asia to northern Queensland. It is also occasionally planted.

Uses

The wood of B. cylindrica is a commonly used as firewood, for making charcoal and in temporary construction. The bark is said to be of some value for tanning. In Malaysia and Indonesia young hypocotyls are occasionally boiled and eaten as a vegetable or preserve, mainly in times of famine. In Vietnam young shoots are served as a salad.

Production and international trade

The wood is mainly gathered from natural stands or from cultivated trees in reforestation areas. No statistics are available on its production and trade.

Properties

The heartwood is reddish to reddish-brown upon exposure, hard, very heavy and strong, with a density of 840-1000 kg/m³ at 15% moisture content. It is straightly grained and finely textured. Growth rings are indistinct or absent. The logs shrink and check excessively in seasoning, while the wood is easy to work and finishes well. It is non-durable when exposed to weather or in contact with the ground. The wood is lighter in weight and colour than Rhizophora wood, but both genera are traded together.

Botany

• A shrub or tree up to 23 m tall, stem diameter 20-30 cm; buttresses small, up to 1 m tall; bark surface grey, warty, with few, small, corky lenticels, inner bark evenly yellow; pneumatophores abundant, knee-like, forming new horizontal and anchor roots.
• Leaves decussately opposite, elliptical or oblong to oblong-lanceolate, 4-17 cm × 2-8 cm, entire, thin, bright green, apex acute, base cuneate, glabrous, usually with about 7 pairs of distinct veins on both surfaces; petiole 1-4.5 cm long; stipules in pairs, 2.0-3.5 cm long, early caducous.
• Inflorescence a cyme, 2-3 flowered; peduncle 6-8 mm long; pedicel 1-4 mm long.
• Flowers greenish, at anthesis 10-12 mm long; calyx tube not ribbed, 4-6 mm × 2 mm, ending in 8 lobes as long as the tube; petals 8, 3-4 mm long, 2-lobed, white, soon turning brown, each lobe with 2 or 3 bristles at the apex, outer margins usually fringed with white hairs at the lower parts; each petal embraces a pair of stamens; stamens 16, 1.5-2.5 mm long; ovary inferior, style filiform, 3-4 mm long.
• Fruit a berry, enclosed by the persistent, sometimes enlarged calyx tube, 10-12 mm long; calyx lobes reflexed, not accrescent; hypocotyl cylindrical, often curved, 8-15 cm × 0.5 cm, grooved or angled, blunt, perforating the apex of the fruit and falling with it.
• Seed solitary, produced in large quantities.

In common with other members of the mangrove species of the Rhizophoraceae, the fruits are viviparous. In B. cylindrica the seed not only forms a hypocotyl, but may develop a considerable, rudimentary root system, while still hanging on the tree. In southern Thailand propagules develop for 3-4 months on the mother tree. The seedling still attached to the fruit drops from the tree, embedding itself in the mud, or floating to where it is washed up on the beach.

If sufficient light is available trees start flowering when 3-4 years old. Pollen is discharged explosively after being triggered by small insect visitors.

B. cylindrica grows under very harsh conditions and is known as the slowest-growing commercially used tree species in Malaysia. It takes over 10 years to reach a height of 6 m and over 15 years to attain a height of 9 m and a stem diameter of 6 cm. At the age of 60 years it has normally attained about 20 cm in diameter. In old naturally regenerated mangrove forest in Peninsular Malaysia the mean annual diameter increment was estimated to be 0.22 cm. Growth of one-year-old seedlings established in the open in mangrove forests in South Thailand was more than 10 times that of seedlings established in the shade.

Ecology

In Malaysia B. cylindrica occupies the highest parts of the mangrove forest along the seacoast, where flooding is occasional only, up to about 20 m above sea level. It is usually absent from mangroves along rivers. On stiff clay soils behind the Avicennia zone, it grows gregariously, being one of the most tolerant species of anaerobic soil conditions. Towards the landward side of mangroves it remains as a scattered tree. On better drained soils it gives way to other species. Where land accretion occurs along the coast, it is a precursor of Rhizophora spp. In New Guinea, it is associated with Rhizophora apiculata Blume, R. mucronata Lamk, Bruguiera sexangula (Lour.) Poiret and Nypa fruticans Wurmb in the mangrove-fresh-water swamp transition zone.

The very poorly aerated soil habitually occupied by B. cylindrica makes the trees highly dependent on their pneumatophores for an adequate supply of oxygen and particularly susceptible to prolonged submersion.

Husbandry

As B. cylindrica is such a prolific seed-bearer a healthy forest normally regenerates, even after clear-felling. Wildlings may be collected and used for planting, but regeneration has, so far, been left to nature in most cases. Young, pure stands can be extremely dense and may contain 55 000-70 000 stems per ha. Due to its extremely slow growth rate it requires a very long harvesting cycle. Its rotation should be longer than the 20 years now generally practised. Harvesting is done manually with an axe or matchet. This minimizes disturbance to the mangrove. Young trees from short-term rotations are preferred. Average annual wood production ranges from 2-16 m³/ha.

Prospects

B. cylindrica is one of the few economic species growing in brackish, anaerobic soil conditions. It requires and deserves increased research attention to attain its potential.

Literature

• Browne, F.G., 1955. Forest trees of Sarawak and Brunei and their products. Government Printing Office, Kuching, Sarawak, Malaysia. pp. 299-301.
• Duran, L.M. & Figarola, D.B., 1992. Phenological study of some mangrove species of Philippine Rhizophoraceae in Punta Dumalag, Davao City, Philippines. CMU (Central Mindanao University) Journal of Science 5: 34-68.
• Haron Abu Hassan, 1981. The Matang mangrove forest reserve, Perak. State Forestry Department, Perak, Malaysia. pp. 2-18.
• Hou, D., 1958. Rhizophoraceae. In: van Steenis, C.G.G.J. (Editor): Flora Malesiana, Series 1, Vol. 5. Noordhoff-Kolff, Djakarta, Indonesia. pp. 457-568.
• Hou, D., 1970. Rhizophoraceae. In: Smitinand, T. & Larsen, K. (Editors): Flora of Thailand. Vol. 2(1). The Forest Herbarium, Royal Forest Department, Bangkok, Thailand. pp. 5-10.
• Melana, D.M., Melana, E.E. & Arroyo, C.A., 1980. Germination study of selected mangrove species. Sylvatrop 5: 207-211.
• Putz, F.E. & Chan, H.T., 1986. Tree growth, dynamics and productivity in a mature mangrove forest in Malaysia. Forest Ecology and Management 17: 211-230.
• Tomlinson, P.B., 1986. The botany of mangroves. Cambridge University Press, Cambridge, United Kingdom. pp. 163-170, 351.

Authors

• T. Boonkerd & H.T. Chan