Artocarpus (PROSEA Timbers)

Plant Resources of South-East Asia
Introduction

Artocarpus J.R. Forster & J.G. Forster

Protologue: Charact. gen. pl.: t. 51 (1775).

Family: Moraceae

Chromosome number: x= 14; Artocarpus altilis: 2n= 27, 28, 54, 56, A. chaplasha, A. gomezianus: 2n= 28, A. heterophyllus: n= 28, 2n= 28, 56, A. lakoocha: n= 28, 2n= 28, 56

Trade groups

Terap: lightweight hardwood, e.g. Artocarpus elasticus Reinw. ex Blume, A. scortechinii King. Timber of Parartocarpus spp. and Antiaris toxicaria (Pers.) Lesch. is also traded as terap; it is similar in properties and uses.

Keledang: medium-weight hardwood, e.g. A. anisophyllus Miq., A. dadah Miq., A. lanceifolius Roxb.

Vernacular names

Terap

Indonesia: teureup (sundanese)
Malaysia: pudau (Sarawak)
Philippines: antipolo
Thailand: ka-ok.

Keledang

Indonesia: selangking, tambang, basang
Malaysia: selangking (Sarawak), beruni (Sabah)
Papua New Guinea: kapiak (general), hang, ham (Wewak)
Philippines: anubing
Laos: 'hat, mi², 'hat mi²
Thailand: khanun, hat, mahat (general).

Origin and geographic distribution

Artocarpus consists of about 50 species and is distributed from Sri Lanka, India, Pakistan and Indo-China towards the Malesian archipelago and the Solomon Islands. The greatest diversity is in the western Malesian area. The species are distributed as follows within Malesia: Peninsular Malaysia 16 species, Sumatra 17, Borneo 23, the Philippines 15, Sulawesi 6, Java 4, the Lesser Sunda Islands 3, the Moluccas 8 and New Guinea 6. Two well-known fruit tree species (breadfruit and jackfruit) are cultivated throughout the tropics.

Uses

Terap is used for light construction, boxes and crates, wooden pallets and veneer (especially for core layers in plywood). The wood is sometimes nicely figured and suitable for decorative purposes, e.g. for furniture, joinery and panelling.

Keledang timber is used for light construction or, when under cover, for construction, house and bridge building, beams, poles, flooring, furniture, joinery, cabinet work, household utensils, musical instruments, telegraph poles, wharves, large canoes, boat building, tool handles, turnery, veneer and plywood. It is the favoured timber for expensive hewn coffins in the Chinese community in Malaysia.

The roots of older A. heterophyllus Lamk trees are highly prized for carving and picture framing.

Many species of Artocarpus are very important fruit producing trees, of which breadfruit (Artocarpus altilis (Parkinson) Fosberg), jackfruit (A. heterophyllus), chempedak (A. integer (Thunb.) Merr.) and marang (A. odoratissimus Blanco) are the most important; their wood is sometimes used. Apart from the fruits, which may be prepared in different ways, seeds are roasted and eaten. Some species yield a yellow dye and the bark of A. heterophyllus yields tannin. The bark of other species yields fibres, used for example, to manufacture cloth and rope. The latex, bark, leaves and roots of some species have medicinal properties and latex may be used for the production of birdlime, as a substitute for milk in sauces, as cooking oil, to mix with wax for batik manufacture or to mix with turpentine and paint. The bark and roots of a few species may be chewed with betel (Areca catechu L.). In Papua New Guinea, the leaves of Artocarpus are used traditionally to scour dirty pots and plates. The leaves of A. lakoocha Roxb. are used as fodder in Nepal and India. Some species are used for reforestation.

Production and international trade

Only comparatively small amounts of terap and keledang timber are traded internationally. The export of terap from Sabah in 1992 was about 9000 m³, mainly as logs, with a total value of US$ 630 000. Small amounts of terap and keledang are imported to Japan, mainly from Sarawak and Papua New Guinea.

Properties

Terap and keledang are not well separated and show much overlap. The arbitrary limit is at a density of 640 kg/m³ at 15% moisture content and the heartwood of keledang is moreover darker and more clearly defined from the sapwood than terap.

Terap is a lightweight hardwood. The heartwood is yellow to pale yellow-brown and usually indistinctly demarcated from the paler sapwood. The density is (310-)365-640(-780) kg/m³ at 15% moisture content. The grain is interlocked, texture coarse but even.

At 15% moisture content, the modulus of rupture is 36-68 N/mm², modulus of elasticity 7410-12 000 N/mm², compression parallel to grain 27-35 N/mm², compression perpendicular to grain 3 N/mm², shear 5-9 N/mm², cleavage 32 N/mm radial and 36 N/mm tangential, Janka side hardness 2070-2650 N and Janka end hardness 3760 N.

The rates of shrinkage are fairly high: from green to 15% moisture content 1.5-2.0% radial and 2.9-4.4% tangential, from green to oven dry 3.2% radial and 7.7% tangential. Terap seasons rapidly to fairly slowly with moderate to slight tendency to bow, cup and check. It takes 1-3 months to dry 15 mm thick boards to air-dry condition, and 2.5-4 months for 40 mm thick boards.

Terap is easy to work. It can be sawn, planed, bored and turned easily, but the quality of finish is often rough, especially on radial surfaces due to grain picking up because of the interlocked grain. It can be peeled satisfactorily and is suitable for plywood production, having good gluability.

Terap is classified as non-durable under tropical conditions when exposed to the weather or in contact with the ground (with a service life of 1-1.5 years). The sapwood absorbs preservatives easily, but the heartwood is moderately difficult to treat, with an absorption of about 75 kg/m³ of creosote using an open tank treatment. A retention of 12.5 kg/m³ has been reported in Indonesia for A. kemando wood using CCA preservative.

Terap wood contains 59-71% holocellulose, 41-45%α-cellulose, 22.5-27.5% lignin, 13-14% pentosan and 0.6-1.4% ash. The solubility is 2.5-6.4% in alcohol-benzene, 1.5-6.2% in hot water and 11.6-16.9% in a 1% NaOH solution.

Keledang is a medium-weight hardwood. The heartwood is orange yellowish-brown, sometimes with an olive-green tinge, generally darkening considerably on exposure and usually well defined from the paler sapwood. The density is (420-)640-875(-945) kg/m³ at 15% moisture content. The density of the wood of the well-known fruit trees A. altilis, A. heterophyllus, A. integer and A. odoratissimus is 505-645 kg/m³, 420-710 kg/m³, 545-790 kg/m³ and 580-780 kg/m³ respectively at 15% moisture content. The grain is often deeply interlocked, texture moderately coarse and even.

At 15% moisture content, the modulus of rupture is 53-107 N/mm², modulus of elasticity 8700-15 500 N/mm², compression parallel to grain 45-65 N/mm², compression perpendicular to grain 5-10 N/mm², shear 9.5-12.5 N/mm², cleavage 45 N/mm radial and 47.5 N/mm tangential, Janka side hardness 4865-5830 N and Janka end hardness 5780-7560 N.

The rates of shrinkage of keledang are moderate: from green to 15% moisture content 0.8-1.2% radial and 1.7-2.6% tangential. The timber seasons moderately slowly with slight degrade; boards of 15 mm thick take about 3.5 months to air dry, boards of 40 mm thick about 4.5 months. The recommended kiln schedule in Malaysia is F.

Keledang is often difficult to saw; saw teeth are severely blunted. This is probably partly a result of the presence of tension wood, and sometimes a result of the presence of silica. The wood can be planed to a smooth surface, but there is some picking up on radial surfaces, boring is moderately easy to difficult and turning is easy. The nailing properties are good. Keledang is of less value than terap for the production of plywood because of its higher density.

Keledang is non-durable to moderately durable; the average service life in contact with the ground under tropical conditions varies between the species from 1.2-3.3 years. The wood is generally comparatively resistant to termite attack but it is more susceptible to powder-post beetle attack. Wood of A. lanceifolius showed some resistance to marine borers. The heartwood is very difficult to impregnate, absorbing only about 16 kg/m³ of preservative using an open tank process.

Keledang wood contains 63-71% holocellulose, 40-44% α-cellulose, 16-25% lignin, 13-14% pentosan and 0.3-1.9% ash. The solubility is 4.6-9.6% in alcohol-benzene, 5.9-13.3% in hot water and 15.6-23.1% in a 1% NaOH solution.

Description

Small to fairly large or sometimes large evergreen or deciduous monoecious trees up to 40(-60) m tall, exuding thick white latex from all parts; bole straight and cylindrical or sometimes irregular, branchless for up to 20 m, up to 150(-300) cm in diameter, sometimes buttressed; bark surface brown or grey to dark grey, inner bark pale brown or yellow-brown to red or pink; sapwood pale yellow or straw-coloured.
Leaves arranged spirally (subgenus Artocarpus) or alternate and distichous (subgenus Pseudojaca), simple, entire to pinnatifid or pinnate, pinnately veined, coriaceous, glabrous to pubescent; stipules large, amplexicaul (subgenus Artocarpus) or non-amplexicaul (subgenus Pseudojaca), often covering the conical bud.
Inflorescence a unisexual, cylindrical to globose head, pedunculate, solitary or paired in leaf axils or rami- or cauliflorous; numerous flowers densely packed together, embedded in the receptacle, the perianths enclosing a single ovary or stamen, usually mixed with abundant stalked interfloral bracts; male head with perianths tubular and bilobed or perforate above, to 2-4-partite, stamens short- to long-exserted; female head with tubular perianths, thin-walled below, thick-walled above, with a narrow lumen containing the style, perianths partially or completely fused with one another to form a syncarp, ovary unilocular, style apical to lateral, simple or bifid.
Aggregate fruit (syncarp) formed by the enlargement of the entire female head; mature ovary thin-walled to fleshy or horny, or developing an indurated endocarp.
Seeds large, without endosperm; embryo straight.
Seedling usually with hypogeal germination (semi-hypogeal in e.g. A. integer).

Wood anatomy

Macroscopic characters:

Heartwood yellow to yellowish-brown or golden brown, often turning darker upon exposure, usually distinctly demarcated from the sapwood in keledang but not in terap.
Grain interlocked.
Texture coarse.
Growth rings indistinct, with sporadic short and fine light-coloured bands; yellowish or whitish chalky substance occasionally present in vessels and orange-coloured substance in ray cells and axial parenchyma, often visible with hand lens, yellowish-brown fine streaks sometimes visible with hand lens in rays on the radial surface.

Microscopic characters:

Growth rings usually indistinct, but when present generally marked by long wings of parenchyma and smaller pores.
Vessels diffuse, usually 3-6(-9)/mm², solitary and in radial multiples of 2-3(-4), the percentage of solitary vessels varying from 45-80% even within a sample, 160-370μm in tangential diameter; perforations simple; intervessel pits alternate, 8-13μm in diameter; vessel-ray and vessel-parenchyma pits enlarged, round to oval and sometimes elongated, with or without borders; yellowish or whitish chalky substance occasionally present; tyloses often abundant and infrequently sclerotic.
Fibres 1.2-2.6 mm long, non-septate, thin- to thick-walled, with fairly distinct but small and comparatively few, simple pits.
Parenchyma vasicentric to aliform, usually with longer wings at ring boundaries, and apotracheal, in diffuse and often interrupted fine lines, in strands of 3-4 cells.
Rays 3-7/mm, 1-8(-10)-seriate, 240-1000μm high, heterocellular with one or more rows of upright marginal cells (mostly Kribs type heterogeneous II or III); sheath cells sometimes present but not well developed.
Vitreous silica reported in fibres of some species.
Latex tubes often present in rays; the occurrence of axial latex tubes has also been reported.

Species studied: A. altilis, A. chaplasha Roxb., A. integer, A. lanceifolius, A. ovatus, A. sepicanus.

Growth and development

Early growth is rapid; for A. elasticus trees the average height is 6-7 m after 2 years and 11-12 m after 7 years with an average diameter of 15.4 cm, i.e. a mean annual diameter increment of over 2 cm. For A. heterophyllus the average height is 3-4 m after 2 years and 10 m after 6 years, whereas the average diameter after 6 years is 12 cm.

Mean annual diameter increment of Artocarpus trees (diverse species) over 10 cm in diameter at breast height is only 0.4-1.9 mm in primary forest in Sarawak. In selectively logged forest this value increases to 1.6-5.2 mm during the first 4 years after logging. Removal of relicts and further liberation thinning yields figures of up to 10.5 mm. For A. scortechinii in natural forest in Peninsular Malaysia a mean annual diameter increment of 1.2-1.6 cm has been recorded and for A. ovatus in natural forest on Mount Maquiling (Luzon) 1.8 cm for the diameter class 10-20 cm, which is very high for trees in natural forest.

Species restricted to the monsoon climate may be evergreen or deciduous. A. heterophyllus and A. altilis demonstrate the architectural growth model of Rauh determined by a monopodial trunk which grows rhythmically and so develops tiers of branches with flowers developing laterally. A. sepicanus represents the model of Roux characterized by a monopodial orthotropic trunk which shows continuous growth and with plagiotropic branches. A. integer also grows continuously and it is probably also a representative of Roux's model.

Annual flowering and fruiting of Artocarpus has been reported and flowering and fruiting may be more or less continuous for the major fruit-producing species, but it may be quite variable per region and per year. During 7 years of observations in Sarawak, A. kemando did not flower at all, A. anisophyllus flowered in one year only, A. odoratissimus in 3 years and A. integer in 4 years. For A. heterophyllus in India it is reported that alternate years have heavy bearing of fruits. Pollination is variable, by small flies and beetles attracted by the sweet scent, but is in other species probably by wind, given that the male flowers are scentless and give off clouds of pollen. Pollination by bats is very likely and may play an important role, as over 25% of guano samples from one bat species (Eonycteris spelaea) in Peninsular Malaysia contained pollen of Artocarpus species. Fruit dispersal is by arboreal mammals and fruit bats, but some of the smaller fruits may be eaten by birds. Fruits borne on the tree trunk may be eaten by herbivores such as elephants, or pigs.

Other botanical information

Artocarpus is most closely related to the genus Prainea and is divided into 2 subgenera, subgenus Artocarpus and subgenus Pseudojaca Trécul, on the basis of whether the leaves are spirally arranged or distichous and whether or not the stipules are amplexicaul.

A. chaplasha and A. lakoocha are fairly well-known timber trees in India and Indo-China.

Ecology

The species of Artocarpus are generally restricted to evergreen forest of the humid tropics or occur in areas with a comparatively mild monsoon climate. They occur commonly as scattered elements of lowland mixed dipterocarp forest and are usually found below 1000 m altitude, but some occur up to 1700 m. The only exception to the scattered occurrence is A. altilis, which acts as a dominant member of riverine swamp forests of New Guinea. Most of the species prefer a clayey soil.

Propagation and planting

Seed weight for some species is as follows: for A. elasticus 1200-1900 seeds/kg and for A. heterophyllus about 430 seeds/kg. Generally, fresh seeds germinate easily: about 85% for A. altilis, 70% for A. anisophyllus, 90% for A. heterophyllus, 95% for A. integer, 40-70% for A. lanceifolius, 80-98% for A. nitidus, almost 100% for A. odoratissimus and 85-95% for A. rigidus. Seeds are usually rated as recalcitrant and lose their viability very rapidly; A. elasticus seeds germinate readily (85%) when sown fresh, but germination decreases to 60% for seeds stored for 1 week and to 0% for seeds stored for 2 weeks. Seeds remain viable when kept inside the fruit, thus storage may be slightly prolonged. Seeds of A. heterophyllus can be stored in a moist condition for one month with final viability of 80%. Heavier seeds remain viable for a longer period.

Germination usually starts 9-40(-60) days after sowing. It starts after 2-4 weeks for A. anisophyllus, 6-9 weeks for A. gomezianus, 3-8 weeks for A. lanceifolius and about 5 weeks for A. lowii.

It has been reported that to promote germination the seeds of A. heterophyllus are heaped and covered with straw. Seedlings should be raised under shade, at 50-70% of full light intensity. A. heterophyllus seedlings soon develop a long taproot, which makes transplanting difficult as disturbance of the roots may be fatal. Transplanting of seedlings with adhering soil is advisable. Root suckers produced by A. altilis can be used for air layering, whereas taking root cuttings is the more common method of propagation. Excised embryos of A. heterophyllus can be kept viable for 4 years in liquid nitrogen (cryopreservation), with a recovery percentage of 60%.

Spacings in trial plantations in Java ranged from 1 m × 1 m to 1 m × 3 m. The denser spacing improved the form of the stem.

A. altilis, A. hirsutus Lamk, A. integer, A. rigidus and A. sericicarpus serve as rootstock for air layering, budding and grafting of other major fruit-producing species of Artocarpus.

Silviculture and management

Artocarpus requires good soil conditions and can grow rather fast. Partial shade should be provided until the plants are well established (e.g. for A. altilis). In mixed plantations of Artocarpus (e.g. A. heterophyllus), the formation of heavy branches is considerably reduced by partial shading and close spacing (1 m × 1 m). In plantations Artocarpus soon forms a closed canopy. Natural pruning is satisfactory, as Artocarpus species are characterized by dense crowns, which also greatly reduces the development of weeds in a plantation. The large amount of litter, which easily decomposes, also reduces weed development. Thinning should be done carefully and only when trees have developed a stem branchless for some length (e.g. 8 m). The mortality of different Artocarpus species over 10 cm diameter in Sarawak was much higher (5-8%) in logged than in undisturbed forest (less than 3%). Trees should not be pruned, as the wounds may cause wood rot and woodboring insects attack the pruned trees. Excellent coppicing is reported from India for A. heterophyllus and A. hirsutus.

Diseases and pests

In A. heterophyllus a serious attack of the fungus Corticium salmonicolor has been observed causing branches and sometimes trees to die. Brown root rot, Phellinus lamaoensis, may develop on stumps of latex-containing species such as Ficus spp. and Artocarpus spp., which may restrict future use of the terrain. However, this fungus is presently believed to beentirely saprophytic. The larva of the moth Glyphodes caesalis bores into tender shoots, flower buds and young fruits of A. heterophyllus and A. rigidus and also feeds on the leaves. Erwinia carotovora causes serious bacterial dieback in A. integer and may eventually kill the tree.

Yield

The formation of heartwood starts only at a late stage: an A. elasticus tree of 40 cm diameter and 17 years old had just started to form heartwood. In a 15-year-old tree of A. heterophyllus, 5-6 cm of sapwood was found.

The mean annual increment of A. elasticus is 20 m³/ha at an age of 17.5 years. For A. heterophyllus the total yield of bole timber is 75 m³/ha at an age of 15.5 years.

Genetic resources

South-East Asia is the main centre of distribution of cultivated Artocarpus fruit trees. Germplasm collections of the main cultivated fruit-producing Artocarpus species are found in several countries inside and outside the region. However, concerning wood characteristics and production no selection has been done nor germplasm collections established.

Prospects

Several Artocarpus species are potentially economically important for use in timber plantations; they are fast-growing and the wood can be used for various purposes.

The use of Artocarpus species as rootstocks to adapt the major fruit-producing species to specific conditions deserves consideration.

Literature

Burgess, H.J., 1956. The timbers keledang and terap. Malayan Forester 19: 36-40.
Burgess, P.F., 1966. Timbers of Sabah. Sabah Forest Records No 6. Forest Department, Sabah. pp. 399-407.
Jarrett, F.M., 1959. Studies in Artocarpus and allied genera, III. A revision of Artocarpus subgenus Artocarpus. Journal of the Arnold Arboretum 40: 113-155, 298-326, 327-368.
Jarrett, F.M., 1960. Studies in Artocarpus and allied genera, IV. A revision of Artocarpus subgenus Pseudojaca. Journal of the Arnold Arboretum 41: 73-109, 111-140.
Khoo, K.C. & Peh, T.B., 1982. Proximate chemical composition of some Malaysian hardwoods. Malaysian Forester 45(2): 244-262.
Lee, Y.H. & Chu, Y.P., 1965. The strength properties of Malayan timbers. Malayan Forester 28: 307-319.
Lopez, D.T., 1984. Malaysian timbers - keledang. Malaysian Forest Service Trade Leaflet No 91. Malaysian Timber Industry Board, Kuala Lumpur. 7 pp.
Malaysian Timber Industry Board, 1986. 100 Malaysian timbers. Kuala Lumpur. pp. 60-61, 200-201.
Seibert, B. & Jansen, P.C.M., 1991. Artocarpus J.R. & G. Forster. In: Verheij, E.W.M. & Coronel, R.E. (Editors): Plant Resources of South-East Asia No 2. Edible fruits and nuts. Pudoc, Wageningen. pp. 79-83.
Tan, Y.E. & Lim, S.C., 1989. Malaysian timbers - terap. Timber Trade Leaflet No 109. Malaysian Timber Industry Board and Forest Research Institute Malaysia. 10 pp.

Selection of species

Authors

T. Djarwaningsih (general part, selection of species),

D.S. Alonzo (properties),

S. Sudo (wood anatomy),

M.S.M. Sosef (selection of species)