6428

5(3): Timber trees; Lesser-known timbers

Tristiropsis Radlk.

T. Durand, Index gen. phan.: 76 (1888).

SAPINDACEAE

x = unknown; 2n = unknown

Tristiropsis (En, trade name).

Tristiropsis comprises 3 species, one of which is widespread and occurs in Christmas Island, the Kangean Archipelago, Borneo (Kalimantan), the Philippines, Sulawesi (Muna), the Lesser Sunda Islands, the Moluccas, New Guinea, the Marianas (Guam), the Caroline Islands (Palau), the Solomon Islands and northern Australia (Queensland); it is cultivated locally in Java. The other two species are endemic to Borneo and Papua New Guinea, respectively.

The wood of Tristiropsis is used for light construction, interior finish, mouldings, light flooring, furniture, joinery, cabinet work, lining, wall panelling, boat building, ladders, turnery, tool handles, and boxes and crates. It is suitable for the production of veneer and plywood as well as for pulp.
T. acutangula is planted locally in Java as an ornamental.

In 1996 Papua New Guinea exported 3125 m³ of Tristiropsis logs at an average free-on-board (FOB) price of US$ 100/m³. Sometimes it is shipped in log consignments together with Pometia pinnata J.R. Forster & J.G. Forster from Papua New Guinea and the Solomon Islands. In other areas the wood is probably used on a local scale only.

Tristiropsis yields a medium-weight hardwood with a density of 580-795 kg/m³ at 15% moisture content. Heartwood pale brown to pink-brown, sapwood pale pink or straw-coloured, 5-8 cm wide; grain straight or interlocked; texture medium to coarse; wood slightly lustrous; often with streaked figure; T. acutangula sometimes with distinct odour. Growth rings indistinct or absent; vessels solitary and in radial multiples of 2-4, visible to the naked eye, with chalky white deposits; parenchyma abundant, apotracheal diffuse and in regular to irregular bands, paratracheal vasicentric, aliform and confluent; rays narrower than the vessels; ripple marks absent.
Shrinkage is very high, but stock can be rapidly kiln dried from the green condition without much degrade. Using moderately severe initial drying conditions, 25 mm thick boards kiln dry from the green condition to 12% moisture content in about 3-4 days and 50 mm thick stock takes 9-10 days. A stress relief treatment is recommended after kiln drying. The wood is moderately weak to moderately strong. It is moderately difficult to saw green stock due to its fibrousness; it is easier to saw when dry. Machining properties are reasonably good, with a satisfactory finish, but grain may pick up on back-sawn material; a cutting angle of 20° is recommended, veneering properties are reasonable. The wood is non-durable. The heartwood is extremely resistant to pressure impregnation, sapwood penetration only patchy. It is liable to sap-stain and subject to pinhole borer and termite attack. The sapwood is susceptible to Lyctus. The wood contains saponin and the sawdust may therefore irritate the nose and throat.
See also the tables on microscopic wood anatomy and wood properties.

Evergreen or semi-deciduous, monoecious, small to fairly large trees up to 35(-53) m tall; bole sometimes straight but often twisted or sinuous, branchless for up to 25(-30) m, up to 100 cm in diameter, often with buttresses up to 3 m high; bark surface smooth to dippled, lenticellate, brownish-grey to brown or reddish-brown, inner bark whitish or pale pinkish tinged with green, with some watery exudate; crown diffuse and somewhat flattened. Leaves alternate, bipinnate, large, exstipulate; pinnae alternate or rarely opposite; leaflets alternate to subopposite, oblique at base, entire. Flowers in an axillary thyrse, unisexual; sepals 5, free, imbricate; petals 5 or absent, creamy white, with a single scale inside; disk entire. Male flower with 8(-13) stamens. Female flower with a superior, 3(-5)-locular ovary with 1 ovule in each cell, style short with a 3-grooved stigma. Fruit a (1-)3(-5)-celled drupe, deep yellow, densely tomentose. Seed brown, without arillode. Seedling with broadly dentate leaflets.
Flowers are sweet-scented and pollinated by insects, probably bees. T. acutangula has been observed flowering in January-August and October-November. The fruits take about 3 months to mature. Fruits were observed from January to November and are probably eaten and dispersed by birds.

T. acutangula is a subcanopy or canopy tree of primary or secondary rain forest up to 500(-850) m altitude. It can be locally common and occurs mainly in areas with a permanent high water table and near the coast on coral limestone. In New Guinea and the Solomon Islands T. acutangula also grows further inland. T. ferruginea is found in primary rain forest on limestone up to 500 m altitude.

Natural regeneration is abundant. Seeds apparently germinate readily, but there are no exact data on propagation. T. acutangula is not fire-resistant.

There are no records of ex situ conservation of Tristiropsis; both species mentioned below are not very common but do not seem to be endangered.

The often poorly shaped bole and the relatively uncommon occurrence of Tristiropsis suggest that the use of the wood is unlikely to increase in the near future.

[70]Backer, C.A. & Bakhuizen van den Brink Jr., R.C., 1963-1968. Flora of Java. 3 volumes. Wolters-Noordhoff, Groningen.
[125]Bolza, E. & Kloot, N.H., 1966. The mechanical properties of 81 New Guinea timbers. Technological Paper No 41. Division of Forest Products, CSIRO, Melbourne. 39 pp.
[300]Eddowes, P.J., 1977. Commercial timbers of Papua New Guinea, their properties and uses. Forest Products Research Centre, Department of Primary Industry, Port Moresby. xiv + 195 pp.
[340]Flora of Australia (various editors), 1981-. Australian Government Publishing Service, Canberra.
[341]Flora Malesiana (various editors), 1950-. Kluwer Academic Publishers, Dordrecht, Boston, London.
[346]Foreman, D.B., 1971. A check list of the vascular plants of Bougainville with descriptions of some common forest trees. Botany Bulletin No 5. Division of Botany, Department of Forests, Lae. 194 pp.
[348]Forest Products Research Centre, 1967. Properties and uses of Papua and New Guinea timbers. Forest Products Research Centre, Port Moresby. 30 pp.
[464]Ilic, J., 1990. The CSIRO macro key for hardwood identification. CSIRO, Highett. 125 pp.
[536]Keating, W.G. & Bolza, E., 1982. Characteristics, properties and uses of timbers. Vol. 1. South-East Asia, northern Australia and the Pacific. Inkata Press Proprietary Ltd., Melbourne, Sydney & London. 362 pp.
[861]Oey Djoen Seng, 1951. De soortelijke gewichten van Indonesische houtsoorten en hun betekenis voor de praktijk [Specific gravity of Indonesian woods and its significance for practical use]. Rapport No 46. Bosbouwproefstation, Bogor. 183 pp.
[974]Salvosa, F.M., 1963. Lexicon of Philippine trees. Bulletin No 1. Forest Products Research Institute, College, Laguna. 136 pp.
[1048]Soepadmo, E., Wong, K.M. & Saw, L.G. (Editors), 1995-. Tree flora of Sabah and Sarawak. Sabah Forestry Department, Forest Research Institute Malaysia and Sarawak Forestry Department, Kepong.
[1132]van Royen, P., 1964-1969. Manual of the forest trees of Papua and New Guinea. 9 parts in 6 volumes. Division of Botany, Department of Forests, Port Moresby.
[1232]Wisse, J.H., 1965. Volumegewichten van een aantal houtmonsters uit West Nieuw Guinea [Specific gravity of some wood samples from West New Guinea]. Afdeling Bosexploitatie en Boshuishoudkunde, Landbouwhogeschool, Wageningen. 23 pp.

P.C. van Welzen

Tristiropsis acutangula
Tristiropsis ferruginea

Van Welzen, P.C., 1998. Tristiropsis Radlk.. In: Sosef, M.S.M., Hong, L.T. and Prawirohatmodjo, S. (Editors): Plant Resources of South-East Asia No 5(3): Timber trees; Lesser-known 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:
Tristiropsis acutangula
Tristiropsis ferruginea