4511

5(2): Timber trees; Minor commercial timbers

Podocarpus L'Hér. ex Persoon

Syn. pl. 2: 580 (1807).

PODOCARPACEAE

x = variable: 10—13, (16—)17—19

Trade groups Podocarp: lightweight to medium-weight softwood, e.g. Podocarpus bracteatus Blume, Podocarpus neriifolius D. Don, Podocarpus rumphii Blume.
The timber is traded as podocarp together with that of the genera Dacrycarpus, Nageia and Prumnopitys.

Podocarp (En, Fr). Indonesia: jamuju (general). Malaysia: podo (general), rempayan (Sabah). Papua New Guinea: low mountain podocarp. Philippines: malakauayan. Burma (Myanmar): thitmin. Laos: ka dong. Thailand: phayamai (general).

Podocarpus consists of about 95 species which are distributed throughout the tropics (often in the highlands) and in temperate forests of the southern hemisphere. Within Malesia 30 species are present; the highest biodiversity is found in New Guinea (15 species) and Borneo (13 species). All other areas within Malesia have much less species, on average about 5.

The wood of Podocarpus is used for high-grade construction, light framing, beams, boat construction, oars, spars, masts, carving, flooring, moulding, cupboards, furniture, cabinet work, interior trim, joinery, drawer sides, weatherboards, shingles, boxes, household utensils, cooperage, matchsplints and veneer.
A decoction of the leaves has medicinal properties and the fruits of some species are edible. Podocarpus polystachyus is cultivated as an ornamental.

Only small amounts of podocarp timber are traded. In Indonesia and Malaysia, podocarp is a much less important softwood than damar minyak (Agathis). In 1987, only 20 m³ of round logs of podocarp were exported from Sabah, but the wood is considered as valuable and ranked in class A; in 1987 the average price was US$ 86/m³. In Papua New Guinea, podocarp timber attracts high prices and the export of logs is banned to encourage domestic processing.

Podocarp is a lightweight to medium-weight softwood. The heartwood is greyish-yellow or pale brown to golden-brown and often not clearly demarcated from the paler sapwood. The density is 415—790 kg/m³ at 15% moisture content. The grain is usually straight, texture fine and even; wood with little or no figure, lustrous.
A test of wood of Podocarpus neriifolius from Fiji at 12% moisture content showed the following mechanical properties: the modulus of rupture 98.5 N/mm², modulus of elasticity 10 765 N/mm², compression parallel to grain 56 N/mm², compression perpendicular to grain 11 N/mm², shear 13 N/mm², cleavage 32 N/mm radial and 40.5 N/mm tangential, Janka side hardness 5050 N and Janka end hardness 7920 N.
The rates of shrinkage of podocarp wood are fairly low: from green to 12% moisture content 2.3% radial and 4.1% tangential, and from green to oven dry 3.3% radial and 5.7% tangential. The wood is easy to dry without significant defects, but face checking and twist are common problems in unweighted boards, whereas juvenile wood checks badly. On average it takes 23 days to dry 25 mm thick boards of Podocarpus neriifolius to 15% moisture content. The recommended kiln drying schedule specifies a temperature of 54—82°C with corresponding relative humidity of 76% to 30%. In Malaysia, it is recommended to dip the stock in an anti-stain solution immediately after conversion and before drying. Boards 25 mm thick are dried to 15% moisture content within 8 days by using the Malaysian kiln-drying schedule G.
Podocarp wood is easy to saw, but softer boards show a tendency to crumble on end grain. The wood can be planed, shaped, turned, mortised and sanded with good results and to a smooth finish, but the results of boring are sometimes rated as moderate. Generally, the wood holds nails well, but large nails may cause some splitting. The gluing, staining, varnishing and painting properties are satisfactory. The peeling properties are rated as good with a negligible degrade upon drying; pretreatment is not needed.
Podocarp wood is classified as non-durable when used in contact with the ground or exposed to the weather. It is susceptible to attacks of termites, pinhole borers, longhorn beetles and marine borers, but not to Lyctus beetles. The sapwood is permeable, but the heartwood is moderately resistant to impregnation.

Usually dioecious, medium-sized or large trees up to 45 m tall, rarely shrubs; bole cylindrical, up to 100 cm in diameter; bark surface more or less fissured and peeling in vertical strips, yellowish to reddish-brown, soft and fibrous; crown broadly conical or dome-shaped; branching of the main stem tending to produce false whorls; apex of leafy shoots with distinct resting buds. Leaves arranged spirally, bifacially flattened, with a single vein, narrowed at base into a short petiole; stomata usually present on the lower surface only. Pollen cones axillary or occasionally terminal, solitary or grouped, sessile or on a short naked peduncle, cylindrical, up to 4 mm in diameter, with a few scales at the base usually shed together with the pollen cone. Seed-bearing structure axillary, with a naked peduncle surmounted by 2(—5) thickened adnate bracts forming a receptacle; receptacle often becoming enlarged and fleshy upon maturity; one to several subterminal bracts fertile; ovule inverted, completely enclosed by a leathery structure often forming a crest at the base of the ovule, the resulting structure exposed above the receptacle. Seed usually more or less green when mature, rarely becoming fleshy or reddish. Seedling with epigeal germination (Podocarpus neriifolius).

— Macroscopic characters:
Heartwood greyish-yellow, pale brown or golden-brown, often not clearly demarcated from the paler sapwood. Grain usually straight. Texture fine and even; wood with little or no figure, occasionally with darker streaks near the pith resulting from compression wood, lustrous. Growth rings generally indistinct, sometimes marked by narrow, dense latewood bands; diffuse parenchyma rarely evident to the naked eye; rays very fine, not visible to the naked eye.
— Microscopic characters:
Tracheids square, rounded, polygonal to irregular in cross-section, radially aligned, tangential diameter approximately 40—65 µm, 2—6 mm long, latewood restricted to 2—3 layers of rectangular, somewhat thicker-walled tracheids in some samples, more extensive in Podocarpus neriifolius; intertracheid pits mainly in radial walls, opposite, in a single row, sometimes paired near tips, moderately large, 16—20 µm in diameter, and rounded, rarely flattened; pits in tangential walls in latewood tracheids smaller. Parenchyma diffuse, moderately abundant to abundant, with smooth end walls. Rays 4—8/mm, predominantly uniseriate, biseriate rays rare, (1—)8—15(—25) cells high; ray cells with smooth end walls; ray-tracheid pits half-bordered, cupressoid to taxodioid, medium-sized, 10—14 µm in diameter, 1—2 per crossfield, crossfields of marginal cells usually containing somewhat larger single pits, usually with a markedly reduced border. Ray tracheids absent, resin ducts absent. Reddish-brown extraneous material abundant in parenchyma cells, less pronounced in ray cells.
Species studied: Podocarpus brassii, Podocarpus neriifolius, Podocarpus pilgeri, Podocarpus polystachyus, Podocarpus rumphii.
Wood of Agathis, Falcatifolium, Nageia, Phyllocladus and Prumnopitys resembles that of Podocarpus. Agathis differs by having alternate intertracheid pits. In Phyllocladus and Prumnopitys parenchyma is absent. However, Falcatifolium and Nageia are very similar.

Growth of Podocarpus neriifolius is slow; the mean annual diameter increment in India is reported to be only 3 mm. A 35-year-old tree of Podocarpus teysmannii Miq. (a usually small tree from Peninsular Malaysia and Sumatra) at the arboretum of the Forest Research Institute Malaysia was 17 m tall and 25 cm in diameter.
Growth is by flushes, with new leaves sometimes distinctly red rather than pale green. Distinct resting buds are formed at the apex of the leafy shoots and consist of two kinds of usually deciduous scales: primary scales covering the resting shoot apex and secondary scales surrounding the newly growing shoots.
Nodules are regularly present on the roots but their function is unclear. They contain endotrophic mycorrhizae; nitrogen fixation is only limited. Growth without mycorrhizae is possible.
Podocarpus neriifolius flowers in Java in November and December and fruits ripen from March to June. Pollination is by wind. Dispersal of the seeds is by birds and fruit-eating bats, and seedlings are found widely scattered.

During the last 30 years, several sections of the large genus Podocarpus have been raised to the genus level (e.g. Dacrycarpus, Nageia, Prumnopitys). This action is disputed by some authors, which may cause confusion as some species are cited with different names depending on the authors' opinions. Similarly, some authors write about Podocarpus in the broader sense, others in the narrower sense. The timber of the newly created genera does not differ much from that of Podocarpus proper. As the treatment in Flora Malesiana applies the narrow genus concept, it seems best to follow that line in the present publication.
The genus Podocarpus (in the narrower sense) is divided into two subgenera based on features of the ovule-bearing shoot and the leaf epidermis. Only subgenus Foliolatus de Laubenf. is represented within the Malesian area; it is mainly characterized by the presence of 2 lanceolate bracts below the receptacle and is further divided into 9 sections.

Most species of Podocarpus occur in montane forest, especially mixed Fagaceous and mixed conifer forest. Individual species are also found in kerangas, in swamp forest on acid soils, but also on limestone hills. Podocarpus polystachyus is the only species of this genus occurring on coastal sands. Some other species also occur down to sea-level, but most are distributed between 750 and 2500 m altitude and may constitute characteristic elements of the vegetation. Several species are found in alpine shrub vegetation up to 3750 m.

Podocarpus can be propagated by seed. There are about 4500 dry seeds of Podocarpus polystachyus in 1 kg. Podocarpus neriifolius seed germinates for 90% in 20—67 days. Seed may not be viable after more than 3 months of storage.
The seedlings are transplanted into the field when 30—40 cm tall. Usually, planting holes spaced 4 m 5 m are prepared one week earlier.

Natural regeneration of Podocarpus neriifolius is sparse in heath forest, although it regularly produces seeds.

Glomerella blight or brown lesion disease in Podocarpus neriifolius is caused by Glomerella cingulata.

Podocarp timber is harvested from natural stands with tree diameters of at least 40—50 cm. The logs are cut into pieces of 3—4 m long and transported by truck or by river.

In natural forest in Central Sulawesi, 2.4—6.0 Podocarpus neriifolius trees/ha were found in the diameter class 35—49 cm (producing 3.4—10.1 m³/ha) and about 2.4 trees/ha with a diameter of 50 cm or more (producing 6.8 m³/ha). On Peleng Island, Central Sulawesi, 1.2 Podocarpus neriifolius trees/ha with a diameter of over 100 cm and an estimated timber volume of 8.2 m³/ha were found.

Podocarpus does not seem particularly endangered as it is widespread and is often common in forest on ridges and mountains which are not easy to reach for logging. Individual species may be liable to genetic erosion, either because they are rare or local endemics (e.g. Podocarpus lophatus de Laubenf. and Podocarpus rotundus de Laubenf. in the Philippines, Podocarpus gibbsii N.E. Gray and Podocarpus brevifolius (Stapf) Foxw. in Borneo), or because they occur in lowland forest which is often subject to logging (e.g. Podocarpus rumphii).

As the wood quality of podocarp timber (including also Dacrycarpus, Nageia and Prumnopitys) is excellent, the prospects for increased use are promising, even though only small quantities may reach the market. Podocarp wood can be considered as a valuable substitute for kauri (Agathis), whose populations have been reduced in many areas. Research on propagation, planting, growth and development, and silviculture is desirable.

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. 34-37.
Burgess, P.F., 1966. Timbers of Sabah. Sabah Forest Records No 6. Forest Department Sabah, Sandakan. pp. 428-431.
de Laubenfels, D.J., 1985. A taxonomic revision of the genus Podocarpus. Blumea 30: 251-278.
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. 337-453.
Gaussen, H., 1976. Les Gymnospermes actuelles et fossiles. Chapter 21: Les Coniférales 13. Le genre Podocarpus. [Present and fossile gymnosperms. Chapter 21: The Coniferales 13. The genus Podocarpus]. Traveaux du Laboratoire Forestier de Toulouse. Tom. 2, Etudes Dendrologiques. Vol. 1. pp. 42-238.
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 and London. p. 279.
Keng, H., 1983. Coniferae. In: Whitmore, T.C. (Editor): Tree flora of Malaya. A manual for foresters. 2nd edition. Vol. 1. Forest Research Institute Malaysia. Longman Malaysia SDN. Berhad, Kuala Lumpur. pp. 48-53.
Martawijaya, A., Kartasujana, I., Mandang, Y.I., Prawira, S.A. & Kadir, K., 1992. Indonesian wood atlas. Vol. 2. Forest Products Research and Development Centre, Bogor. pp. 86-91.
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.
Wasscher, J., 1941. The genus Podocarpus in the Netherlands Indies. Blumea 4: 359-542.

R.E. Nasution (general part, selection of species), D.S. Alonzo (properties), J. Ilic (wood anatomy)

Podocarpus archboldii
Podocarpus bracteatus
Podocarpus brassii
Podocarpus crassigemmis
Podocarpus insularis
Podocarpus laubenfelsii
Podocarpus ledermannii
Podocarpus neriifolius
Podocarpus pilgeri
Podocarpus polystachyus
Podocarpus rumphii

Nasution, R.E., Alonzo, D.S. & Ilic, J., 1995. Podocarpus L'Hér. ex Persoon. 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:
Podocarpus archboldii
Podocarpus bracteatus
Podocarpus brassii
Podocarpus crassigemmis
Podocarpus insularis
Podocarpus laubenfelsii
Podocarpus ledermannii
Podocarpus neriifolius
Podocarpus pilgeri
Podocarpus polystachyus
Podocarpus rumphii