4121

5(2): Timber trees; Minor commercial timbers

Dacrydium Sol. ex J.G. Forster

De pl. escul. insul. oceani austr. comm. bot.: 80 (1786).

PODOCARPACEAE

x = 10, 15; Dacrydium elatum: 2n = 20

Trade groups Sempilor: lightweight to medium-weight softwood, e.g. Dacrydium beccarii Parl., Dacrydium elatum (Roxb.) Wallich ex Hook., Dacrydium nidulum de Laubenf.
The timber is traded as sempilor together with that ofFalcatifolium and Phyllocladus. In Indonesia, all Podocarpaceae timber is traded as "melur"".

Sempilor: meloor (Am, En, Fr). Indonesia: melur (general), kayu alau (Kalimantan). Malaysia: ekor (Peninsular), melor (Sarawak, Sabah). Papua New Guinea: dacrydium. Philippines: lokinai (general). Cambodia: srol-kraham. Thailand: samphanpi (north-eastern), son-hangkarok (central), phayamakhampom (south-eastern). Vietnam: hoang dan. Burma (Myanmar): taw-kyet-gale-pan.

Dacrydium consists of about 25 species and is distributed from mainland South-East Asia through Malesia (but not on Java and the Lesser Sunda Islands except for Sumba), towards New Caledonia, Fiji, Tasmania, New Zealand and southern Chile. The greatest numbers of species are found in Borneo (7), New Guinea (6), Peninsular Malaysia (5), the Moluccas (5), and outside the Malesian area in New Caledonia (4) and New Zealand (4).
Dacrydium has a long fossil record dating back to the Middle Jurassic and Upper Cretaceous floras of western Antarctica. The centre of origin is believed to have been located in the Australian-New Zealand region, where the most primitive species are distributed.

Dacrydium timber is resinous and relatively hard and used for light construction, furniture, joinery, mouldings, light traffic flooring, door and window frames, masts, interior finish, novelties, veneer and plywood, and packing-cases. It is suitable for pulp and paper.
A volatile oil resembling commercial cedar oil can be distilled from the wood.
Dacrydium elatum is planted as an ornamental tree.

No statistics are available on the trade of Dacrydium timber. In Papua New Guinea, timber of Dacrydium commands high prices, just like other conifer woods, and the export of logs is banned to encourage local processing and obtain added value.

Dacrydium yields a lightweight to medium-weight softwood. The heartwood is yellow-brown, pinkish-yellow, golden, pale brown to brown or red-brown, not clearly demarcated from the paler sapwood. The density is 425—720 kg/m³ at 15% moisture content. The grain is straight, rarely wavy, texture fine and even. The wood generally lacks figure, occasionally with fine dark streaks giving an attractive appearance and without taste or odour.
A test on the mechanical properties of Dacrydium nidulum wood in Fiji at 12% moisture content showed the following figures: the modulus of rupture 106 N/mm², modulus of elasticity 11 590 N/mm², compression parallel to grain 61.5 N/mm², shear 14 N/mm², cleavage 38 N/mm radial and 54.5 N/mm tangential, Janka side hardness 5430 N and Janka end hardness 8635 N.
The rates of shrinkage are fairly low to moderate: from green to 12% moisture content2.0% radial and 4.5% tangential. The wood seasons well with very little collapse, but thicker boards must be dried slowly to avoid surface checking. Warping in the form of slight to moderate twist may occasionally occur, while backsawn boards may cup to a slight extent. The recommended kiln schedule is at a dry bulb temperature of 65—80°C. Kiln-drying 25 mm thick boards of D. nidulum wood from green to 12% moisture content takes 3—4 days and 50 mm thick boards take about 2 weeks; the timber can also easily be air dried under cover. A high humidity treatment should be given, to relieve stresses, but when considerable twist occurs, a saturated steaming treatment for 2—4 hours should be given instead. The wood is stable in service.
Dacrydium timber is easy to saw and works well with hand and machine tools. The wood planes and turns well to a smooth surface and takes a high polish. Gluing, nailing and peeling properties of Dacrydium elatum are satisfactory. Dacrydium nidulum is not suitable for face veneer, as it may buckle during drying. Sawdust of Dacrydium nidulum may cause irritation to nose and throat.
Sempilor is classified as non-durable when used in contact with the ground or exposed to the weather in the lowland tropics. At higher elevations or in a temperate climate, however, it is considered fairly durable. It is susceptible to termite and marine borer attack. Dacrydium nidulum is resistant to decay and termites, but susceptible to pinhole borer attack. Sempilor is not susceptible to Lyctus attack. The sapwood is probably moderately resistant to impregnation but the heartwood is resistant.
Dacrydium beccarii wood contains 53% cellulose, 29.2% lignin, 18.1% pentosan, 0.6% ash and 0.4% silica. The solubility is 5.6% in alcohol-benzene, 3.3% in cold water, 6.8% in hot water and 15.2% in a 1% NaOH solution. The energy value of Dacrydium beccarii wood is 17 320 kJ/kg.
The volatile oil that can be distilled from the wood consists largely of cedrene and cedrol.

Usually dioecious, evergreen, small to fairly large trees up to 40 m tall, or less often shrubs; bole cylindrical, up to 70(—100) cm in diameter; bark surface hard and smooth with fissures, breaking off in plates, with many small lenticels, dark or reddish-brown and weathering to grey; branches often ramified, often curving upwards and the ultimate branches aggregated into dense tufts. Leaves arranged spirally, variable, from small appressed scales to linear or needle-like, straight to strongly incurved at the tip, tetragonal in cross section or keeled on the dorsal side and flat or concave on the upper surface, blunt to narrowly acute; juvenile leaves spreading at about 75° and bent forward in a gradual curve, lanceolate or linear-lanceolate, strongly keeled on the dorsal side, generally longer and more slender than the mature leaves. Fertile structure terminal or lateral or on short lateral branches. Pollen cone solitary or clustered, cylindrical, with sterile vestigial leaves at the base; microsporophyll with a triangular or marked lanceolate apex. Seed-bearing structure usually solitary, with slightly enlarged scale-like bracts or with leaf-like bracts at the base, the entire structure often becoming enlarged, fleshy and red when mature; ovule solitary, with a slightly to distinctly inverted apex gradually turning up as the seed develops. Seed ovoid, laterally keeled, dark brown.

— Macroscopic characters:
Heartwood yellow-brown, pinkish-yellow, golden, pale brown to brown or red-brown, not always clearly demarcated from the paler sapwood. Grain straight, texture fine and even; wood with little or no figure, occasionally with fine darker streaks, with little or no lustre. Growth rings generally indistinct; diffuse parenchyma rarely evident to the naked eye; rays very fine, not visible to the naked eye.
— Microscopic characters:
Growth rings barely marked, tracheid wall thickness in latewood little different from that in earlywood. Tracheids square, rounded, polygonal to irregular in cross-section, radially aligned, tangential diameter approximately 40—55 µm, 3—5 mm long; intertracheid pits mainly in radial walls, usually in 1 row, sometimes opposite and paired, loosely scattered, moderately large (16—20 µm in diameter), rounded, sometimes flattened axially; smaller pits on tangential walls in latewood, tracheids loosely scattered. Parenchyma diffuse, scattered uniformly singly or in small groups, moderately abundant to abundant, end walls thin and smooth. Rays 4—8/mm, predominantly uniseriate, biseriate rays rare, (1—)6—15(—20) cells high, end walls smooth; ray-tracheid pits half-bordered, taxodioid to cupressoid, medium-sized, 12—15 µm in diameter, 1—2 per crossfield, crossfields of marginal cells sometimes containing somewhat larger pits, often with a markedly reduced border. Ray tracheids absent, resin ducts absent. Reddish-brown extraneous material abundant in parenchyma cells, less in ray cells.
Species studied: Dacrydium beccarii, Dacrydium elatum, Dacrydium nidulum.
Wood of Agathis, Dacrycarpus, Falcatifolium, Nageia, Phyllocladus, Podocarpus and Prumnopitys can resemble Dacrydium. Agathis differs from the other genera by having alternate intertracheid pits. In Phyllocladus and Prumnopitys, parenchyma is absent. Dacrycarpus, Falcatifolium, Nageia and Podocarpus are very similar to Dacrydium, although in Dacrycarpus the rays are somewhat higher.

Root nodules have been observed in Dacrydium, but it is unknown whether these fix nitrogen.

Dacrydium is thought to be closely related to Falcatifolium because of the similarity in their seed-bearing structure but the latter is easily distinguished by its bilaterally flattened leaves. Some species of Dacrydium show similarities with those of Halocarpus. The small genera Lagarostrobus and Lepidothamnus, incorporating some Tasmanian, New Zealand and Chilean species, are sometimes separated from Dacrydium.
Dacrydium cupressinum Sol. ex J.G. Forster is a fairly well-known and valuable timber tree in New Zealand.

Dacrydium generally occurs in primary rain forest. It is a canopy tree and usually occurs scattered but is sometimes common and dominant or might even be present in pure stands. It has a preference for boggy or peaty locations. Some of the species occur in the lowland down to sea-level, but the majority are found on hills and mountains at 600—2500(—2700) m altitude.

Dacrydium can be propagated by seed, wildlings or cuttings. Fruits are macerated carefully to remove the fleshy receptacles. Seed should be graded by flotation, discarding empty ones, and sown in nursery beds immediately after collection. In Dacrydium comosum Corner, a shrub of montane forest in Peninsular Malaysia, 8% of the seed germinate in 16—52 weeks. The nursery beds must be shaded, as seedlings do not thrive in full light. In Peninsular Malaysia planted wildlings of Dacrydium elatum succeed under favourable weather conditions.

Dacrydium elatum is a light-demander. Natural regeneration is abundant in gaps, but is sparse elsewhere. It responds very well to liberation thinning, when not too intensive. Regeneration of pure stands of Dacrydium pectinatum in Sabah and Sarawak after exploitation proved very difficult, due to the nearly complete removal of all mother trees.

The mistletoe Korthalsella dacrydii (Ridley) Dans. has been observed on Dacrydium, but is probably insignificant.

Logs of Dacrydium elatum as small as 25 cm in diameter are exploited in Sarawak. Exploitation of timber for construction purposes in remote, mountainous areas is common.

A high timber volume of Dacrydium and Falcatifolium faciforme (Parl.) de Laubenf. trees over 50 cm in diameter was found in Riau (14.4 m³/ha) and in East Kalimantan (5.6 m³/ha). The volume of these species with a diameter of 10 cm or more is estimated at 17.1 m³/ha in Central Kalimantan and is a resource for pulp and paper manufacture.

Species such as Dacrydium beccarii and Dacrydium elatum occur gregariously and widespread and are not liable to genetic erosion. Pure stands of Dacrydium pectinatum, a species only locally common in Sabah and Sarawak on isolated patches of sandy podzol in peat swamp, have been almost completely logged; this species is vulnerable to genetic erosion.

Supply of Dacrydium timber to the market is decreasing due to over exploitation and inherent poor regeneration. The excellent quality of the timber, however, justifies increased efforts to achieve proper forest management and plantation establishment.

Bolza, E. & Kloot, N.H., 1972. The mechanical properties of 56 Fijian timbers. Division of Forest Products Technological Paper No 62. Commonwealth Scientific and Industrial Research Organization, Melbourne. pp. 44-47.
Burgess, P.F., 1966. Timbers of Sabah. Sabah Forest Records No 6. Forest Department, Sabah, Sandakan. pp. 424-426.
de Laubenfels, D.J., 1978. The taxonomy of Philippine Coniferae and Taxaceae. Kalikasan 7: 117-152.
de Laubenfels, D.J., 1988. Coniferales. In: van Steenis, C.G.G.J. & de Wilde, W.J.J.O. (Editors): Flora Malesiana. Ser. 1, Vol. 10. Kluwer Academic Publishers, Dordrecht, Boston, London. pp. 360-371.
Gaussen, H., 1974. Les Gymnospermes actuelles et fossiles. Chapitre 20: les Coniférales 12. [Contemporary and fossil gymnosperms. Chapter 20: the Coniferales 12.]. Travaux du Laboratoire Forestier de Toulouse. Tom. 2, Etudes dendrologiques. Vol. 1, part. II-3. pp. 13-66.
Hair, J.B. & Beuzenberg, E.J., 1958. Chromosomal evolution in the Podocarpaceae. Nature 181: 1584-1586.
Keating, W.G. & Bolza, E., 1982. Characteristics, properties and uses of timbers. Vol. 1: South-east Asia, Northern Australia and the Pacific. Division of Chemical Technology, Commonwealth Scientific and Industrial Research Organization. Inkata Press, Melbourne, Sydney, London. pp. 110-111.
Keng, H., 1983. Coniferae. In: Whitmore, T.C. (Editor): Tree flora of Malaya. A manual for foresters. 2nd edition. Vol. 1. Malayan Forest Records No 26. Forest Research Institute Malaysia. Longman Malaysia SDN. Berhad, Kuala Lumpur. pp. 44-48.
Page, C.N., 1990. Podocarpaceae. In: Kramer, K.U. & Green, P.S. (Editors): The families and genera of vascular plants I. Pteridophytes and Gymnosperms. Springer Verlag, Berlin, Heidelberg. pp. 332-346.
Quinn, C.L., 1982. Taxonomy of Dacrydium Sol. ex Lamb. emend. de Laub. (Podocarpaceae). Australian Journal of Botany 30: 311-320.

H.C. Ong (general part), E. Boer (properties), J. Ilic (wood anatomy), M.S.M. Sosef (selection of species)

Dacrydium beccarii
Dacrydium cornwalliana
Dacrydium elatum
Dacrydium nidulum
Dacrydium pectinatum
Dacrydium xanthandrum

Ong, H.C., Boer, E., Ilic, J. & Sosef, M.S.M., 1995. Dacrydium Sol. ex J.G. Forster. In: Lemmens, R.H.M.J., Soerianegara, I. and Wong, W.C. (Editors): Plant Resources of South-East Asia No 5(2): Timber trees; Minor commercial timbers. PROSEA Foundation, Bogor, Indonesia. Database record: prota4u.org/prosea

The following species in this genus are important in this commodity group and are treated separatedly in this database:
Dacrydium beccarii
Dacrydium cornwalliana
Dacrydium elatum
Dacrydium nidulum
Dacrydium pectinatum
Dacrydium xanthandrum