4529

5(2): Timber trees; Minor commercial timbers

Quercus L.

Sp. pl. 2: 994 (1753); Gen. pl. ed. 5: 431 (1754).

FAGACEAE

x = 12; 2n = 24 for the majority of species throughout the world, Quercus castaneifolia A. Camus: 2n = 28, Quercus lineata: n = 12

Trade groups Mempening: medium-weight to heavy hardwood, e.g. Quercus argentata Korth., Quercus gemelliflora Blume, Quercus lineata Blume.
Mempening includes the timber of Lithocarpus spp. as well as of Quercus spp.

Mempening: oak, Sunda oak (En). Chêne (Fr). Indonesia: pasang (general). Thailand: ko (general).

Quercus consists of about 600 species, most of which are northern temperate. They occur from North America towards north-western South America, in Europe and from North Africa across the Middle East and the Himalayas towards eastern Asia, north-eastern India across Indo-China to Thailand, and the western Malesian area where 19 species are found. The Malesian species are distributed as follows: Peninsular Malaysia (8 species), Sumatra (10 species), West and Central Java (5 species), Borneo (18 species) and Palawan (1 species). Many fossils dating back as far as the Upper Cretaceous have been reported, mainly from North America including Canada and Alaska, Greenland and Europe, but also from Japan, Korea, Manchuria and India.

The timber is used for medium to heavy construction, provided that it is not in contact with the ground, e.g. for beams, posts and boards in house and bridge construction, poles for carts, tool handles, furniture and carpentry. It is also suitable for interior finish, panelling, parquet flooring and decorative veneer, and is also used as firewood.
The bark sometimes yields tannin. In Borneo, logs of some species have been tried for the cultivation of mushrooms. Quercus lineata has proved useful for erosion control of steep slopes in montainous regions.

In South-East Asia Quercus timber is traded together with that of Lithocarpus, which is much more abundant, as mempening. In 1987, the export of mempening round logs from Sabah was about 650 m³ with a value of US$ 45 000, but in 1992 the export had increased considerably to 12 750 m³ (17% as sawn timber and 83% as logs) with a total value of US$ 1.1 million (US$ 187/m³ for sawn timber, US$ 70/m³ for logs). However, the wood is mostly consumed by local people. Japan imports comparatively small amounts of mempening, mainly from Sabah and Sarawak.

Quercus wood is medium-weight to heavy and moderately hard to hard. The heartwood is grey-brown to dark brown-red, sometimes with a yellow tinge, and clearly demarcated from the paler sapwood. The density is (520—)815—1100 kg/m³ at 15% moisture content. The grain is straight or slightly wavy, texture coarse.
At 15% moisture content, the modulus of rupture is 120—127 N/mm², modulus of elasticity 17 740—18 100 N/mm², compression parallel to grain 53—62.5 N/mm², compression perpendicular to grain c. 12 N/mm², shear 9—16 N/mm², cleavage 78—92 N/mm radial and 66 N/mm tangential, and Janka side hardness 5735—10 640 N.
The wood air dries rather slowly and is liable to some bowing, end checking and splitting; it may suffer from staining. Conversion of green timber into planks and close piling during drying may prevent heavy degrade. Boards 15 mm thick take about 2 months to air dry, boards 40 mm thick take 5 months.
Mempening wood is slightly difficult to resaw and cross cut, especially when air dry. Planing and boring are generally easy with smooth finish, but turning is difficult with rough finish. The resistance to splitting when nailed is rated as moderate. Good veneer can be obtained at a peeling angle of 92°30' without pretreatment.
The wood is rated as moderately durable. Mempening test stakes showed an average service life in contact with the ground of 3.7 years in Malaysia. The wood is reputed to be attacked by termites when in contact with the ground. The heartwood is probably difficult to impregnate because of the presence of tyloses.

Monoecious, evergreen, small to fairly large trees up to 40 m tall, sometimes forming clumps; bole up to 130 cm in diameter, sometimes buttressed with thick, equal to steep buttresses up to 2.5 m high, or basally fluted, rarely stilt-rooted; bark surface smooth to shallowly fissured or scaly, with prominent lenticels, pale yellow to greyish-brown, inner bark with broad hard rays penetrating the cambium, cream to orange or red to brown. Leaves arranged spirally, simple, margin entire or minutely serrate in the apical half, glabrous to densely pubescent or tomentose at least below; petiole thickened at base; stipules extrapetiolar, linear-acute, caducous. Inflorescence unisexual, spicate; male inflorescence solitary in the axils of lower leaves or in paniculate clusters on the lateral or subterminal young shoots, pendulous, simple or branched; female inflorescence solitary in the axils of higher leaves, erect, simple, few- to many-flowered. Male flowers in clusters of 3—4; perianth segments (4—)6, connate at base, densely tomentose; stamens (4—)6(—9), with slender filaments and large basifixed anthers; pistillode absent or replaced by a tuft of hairs. Female flowers solitary; perianth segments (4—)6(—9), connate at base; staminodes 0 or 5—7; styles 3—4(—6), free or connate at base, stigmas broadly capitate; ovary cells as many as the styles. Cupule cup- or saucer-shaped, with raised ring-like flanges, hairy on both sides. Fruit an indehiscent nut (acorn), 1 per cupule, glabrous to densely tomentose, apex umbonate, the umbo with many rings. Seed 1, exalbuminous; cotyledons flat-convex. Seedling with hypogeal germination; leaves conduplicate, alternate-spiral at the first few nodes or replaced by scales.

— Macroscopic characters:
Heartwood grey-brown to dark brown-red, sometimes with a yellow tinge, clearly demarcated from the paler sapwood. Grain straight or slightly wavy. Texture coarse. Growth rings absent to distinct (depending on provenance of the species); vessels visible to the naked eye, in radial to diagonal pattern; parenchyma barely visible with a hand lens; broad rays conspicuous and causing silver grain on quarter-sawn surfaces.
— Microscopic characters:
Growth rings absent in equatorial tropical species, but distinct in species from other areas (e.g. Vietnam). Vessels in a diagonal to radial pattern, 5—8(—10)/mm², exclusively solitary, very rarely in pairs due to overlapping ends, round to oval, average tangential diameter 100—200 µm; perforations simple; intervessel pits not observed; vessel-ray and vessel-parenchyma pits typically elongated and simple or with reduced borders; helical thickenings and deposits absent; tyloses usually present. Vasicentric tracheids abundant, forming radial, oblique or flame-like tissue bands together with the vessels. Fibres 900—2200 µm long, non-septate, medium to very thick-walled, with minutely bordered pits mainly confined to the radial walls. Parenchyma apotracheal, typically diffuse, diffuse-in-aggregates and in short uniseriate lines, in 6—8-celled strands. Rays of two distinct sizes, uniseriate rays 10—12/mm, 5—12 cells high, multiseriate rays many (up to over 20) cells and 0.2—0.6 mm wide and 2—6(—12) mm high, often compound or intergrading with ray aggregates, typically homocellular, composed of procumbent cells, but broad rays sometimes weakly heterocellular and with square to upright marginal cells; some ray cells extremely thick-walled and fibre-like. Crystals prismatic, in chambered axial parenchyma and ray cells.
Species studied: Quercus gemelliflora, Quercus lineata, Quercus oidocarpa.

In seedlings shoot growth is intermittent after the first few nodes, with the leaves clustered at the top of each flush. Under favourable conditions in Java, seedlings may attain a height of 0.5 m after 1 year, 2 m after 3 years and 3 m after 5 years.
A Quercus gemelliflora tree planted in an arboretum in Malaysia reached a height of 18 m after 38 years, with a bole branchless for 6.5 m and a diameter of 24 cm, i.e. a mean annual diameter increment of 0.6 cm.
As in most, or perhaps all Fagaceae, the trees seem to live in symbiosis with ectotrophic mycorrhiza (Agaricales). Flowering usually coincides with young flushes, often at the beginning of the rainy season. Pollination is by wind. The comparatively large and heavy fruits fall close to the mother tree; they do not float in water.

Quercus and Lithocarpus were formerly considered as a single genus because of their similar cupules. This similarity, however, is the result of convergent evolution. In Quercus a cupule develops below a 3-flowered dichasium (a dichasium cupule) but the 2 lateral flowers are reduced, resulting in a solitary flower in the cupule. Within Lithocarpus a cupule develops below each female flower in a 3—7-flowered dichasium (a flower cupule). In some species the lateral flowers reduce, resulting in a similar but ontogenetically different solitary flower. Actually, Quercus and Lithocarpus are considered as evolutionarily far apart. Furthermore, Quercus differs from Lithocarpus particularly by its unisexual inflorescences, its pendulous male inflorescences, and its male flowers usually having 6 stamens with basifixed large anthers. Lithocarpus has uni- or bisexual inflorescences, erect male inflorescences, and male flowers usually with 12 stamens with dorsifixed small anthers.
All Malesian species of Quercus belong to the subgenus Cyclobalanopsis (Oersted) Schneider, which is confined to eastern and south-eastern Asia.

In Malesia, Quercus often constitutes canopy and subcanopy elements of primary evergreen lowland and especially of lower montane rain forest. Species occur from sea-level up to 3350 m altitude, with a preference for the region between 600 and 1500 m, in various types of forest, i.e. mixed dipterocarp forest, swamp forest, kerangas, and ridge forest. They are usually found on sandy clay or sandy loam soils, but are also reported from ultrabasic soil overlying sandstone or granite. In lower montane forest in North Sumatra Quercus is found on a yellowish-brown andosol with ultrabasic volcanic ash and a pH of 4.5—6.5, and growing together with Calophyllum, Castanopsis, Cinnamomum, Endospermum, Litsea and Syzygium species. In a lowland peat-swamp forest dominated by Shorea spp. in Riau, Sumatra, Quercus was found together with Alstonia, Cratoxylum, Durio, Gonystylus and Palaquium species.

Quercus can be propagated by seed, including direct sowing, and wildling collection. The number of nuts per kg is about 165 for Quercus lineata. Seed needs shade for germination. In a small germination trial conducted for Quercus oidocarpa 12 of the 20 seeds sown germinated in 12—37 days.
Seedlings can be planted when 25—30 cm tall, but great care must be taken during transport to avoid damaging the main root. Damage may cause root rot. Stumping has been attempted in Quercus lineata with stumps of 20 cm long and 0.5 cm diameter but none of the stumps planted survived. A spacing of 3 m 2 m is recommended for planting.
Wildling collection is known from Sumatra and the application of the growth hormone rootone F stimulated height and diameter increment. Survival of wildlings was 50—60%. Direct seeding is possible for cleared fields. Natural regeneration in primary forest is generally sparse.

An inventory of natural regeneration of Quercus in North Sumatra revealed that there were seedlings and saplings in abundance. Therefore, Quercus has been incorporated in a local reforestation project instead of the Pinus and Acacia species used previously. In these pure stands it is expected that clear cutting with natural regeneration can be applied with a rotation of 60 years. Quercus lineata has been used to underplant Pinus merkusii Junghuhn & de Vriese plantations in Java. Like other Malesian Fagaceae, Quercus is not resistant to fire nor does it regenerate under pyrogenous conditions.

Attacks by the fungus Fomes pinicola, the beetle Coraebus dorsalis and the caterpillar Zeuzera multistrigata have been reported in Quercus lineata. Monkeys, pigs and wild boars are known to feed on the fruits, thus limiting the potential for natural regeneration in silvicultural management.

The timber should be treated with anti-stain chemicals immediately after sawing.

Quercus does not seem to be very liable to genetic erosion. Together with Lithocarpus spp., Quercus spp. dominate or co-dominate in mid-montane forest in western Malesia. The economic value of the timber is slight in most regions, and selective logging on a larger scale is practised only locally in Borneo. Several species, however, occur only very locally and need protection (e.g. some species are found only or mainly on Mount Kinabalu, Sabah, other species only very locally in Sarawak, and one species very locally in North Sumatra). Quercus trees are planted on a very small scale in South-East Asia, especially in botanical gardens.

It is unlikely that Quercus, like Lithocarpus, has great prospects as a timber plantation tree. The trees are comparatively slow growing, and the timber is often refractory in drying and working. However, it is considered as promising in sustainably managed forests in mountainous areas, where more favourable timber-producing species such as Shorea spp. do not grow well.

Breteler, F.J., 1989. Quercus lineata Blume. In: Westphal, E. & Jansen, P.C.M. (Editors): Plant Resources of South-East Asia. A selection. Pudoc, Wageningen pp. 236-237.
Cockburn, P.F., 1976. Trees of Sabah. Sabah Forest Record No 10. Vol. 1. Forest Department Sabah. Borneo Literature Bureau. pp. 115-118.
Cockburn, P.F., 1983. Fagaceae. In: Whitmore, T.C. (Editor): Tree flora of Malaya. A manual for foresters. Revised edition. Vol. 1. Forest Research Institute Malaysia. Longman Malaysia SDN. Berhad, Kuala Lumpur. pp. 196-232.
Forman, L.L., 1966. On the evolution of cupules in the Fagaceae. Kew Bulletin 18: 385-420.
Kapisa, N. & Sapulete, E., 1989. Kemungkinan Quercus sp. sebagai tanaman reboisasi kawasan Sipiso-piso [The possibilities of planting Quercus sp. for reforestation in the Sipiso-piso complex]. Buletin Penelitian Kehutanan Pematang-Siantar 5(1): 57-66.
Lee, Y.H., Engku Abdul Rahman Chik & Chu, Y.P., 1979. The strength properties of some Malaysian timbers. Malaysian Forest Service Trade Leaflet No 34. Malaysian Timber Industry Board, Kuala Lumpur. 107 pp.
Martawijaya, A., Kartasujana, I., Kadir, K. & Prawira, S.A., 1986. Indonesian wood atlas. Vol. 1. Forest Products Research and Development Centre, Bogor. pp. 111-115.
Sapulete, E., 1988. Pengaruh hormon rootone F terhadap pertumbuhan anakan kimbang (Castanopsis sp.) dan hoting (Quercus sp.) [The effect of rootone F hormone on the growth of kimbang (Castanopsis sp.) and hoting (Quercus sp.) seedlings]. Buletin Penelitian Kehutanan Pematang-Siantar 4(3): 39-43.
Soepadmo, E., 1968. A revision of the genus Quercus L. subgen. Cyclobalanopsis (Oersted) Schneider in Malesia. Gardens' Bulletin, Singapore 22: 355-427.
Soepadmo, E., 1972. Fagaceae. In: van Steenis, C.G.G.J. (Editor): Flora Malesiana. Ser. 1, Vol. 7. Noordhoff International Publishing, Leiden. pp. 265-403.

B. Sunarno (general part, selection of species), W.C. Wong (properties), Nguyen Dinh Hung (wood anatomy), M.S.M. Sosef (selection of species)

Quercus argentata
Quercus elmeri
Quercus gaharuensis
Quercus gemelliflora
Quercus kerangasensis
Quercus lineata
Quercus oidocarpa
Quercus sumatrana
Quercus treubiana
Quercus valdinervosa

Sunarno, B., Wong, W.C., Nguyen Dinh Hung & Sosef, M.S.M., 1995. Quercus L.. 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:
Quercus argentata
Quercus elmeri
Quercus gaharuensis
Quercus gemelliflora
Quercus kerangasensis
Quercus lineata
Quercus oidocarpa
Quercus sumatrana
Quercus treubiana
Quercus valdinervosa