Araucaria cunninghamii (PROTA)
Araucaria cunninghamii Aiton ex D.Don
- Protologue: Lamb., Descr. Pinus ed. 2, 3: t. 79 (1837).
- Family: Araucariaceae
- Chromosome number: 2n = 26
- Hoop pine, colonial pine, Richmond River pine, Moreton Bay pine (En).
- Pin de Hoop, araucaria (Fr).
Origin and geographic distribution
Araucaria cunninghamii occurs naturally in New Guinea and eastern Australia. Plantations have been established within these regions and also in Indonesia, Malaysia, Thailand, the Philippines, India, the Solomon Islands, Costa Rica, Venezuela, Argentina, and several African countries. Large-scale plantations exist in South Africa, and small-scale or trial plantations have been established in Côte d’Ivoire, Nigeria, Congo, central Uganda, Zimbabwe, Madagascar and Mauritius, whereas the tree is occasionally planted as an ornamental elsewhere in Africa.
Araucaria cunninghamii yields an excellent timber, which is used for all kinds of light construction and interior work, including mouldings, linings, panelling, domestic flooring, shelves, cupboards, general joinery, furniture and cabinet work. Special applications are matches, chopsticks and implements. The timber is suitable for high-quality plywood and for premium grade pulp. The tree is also planted as an ornamental. The seeds are edible and eaten in tropical America.
Production and international trade
Araucaria timber is commercially important. Plywood was a major export item from Papua New Guinea until 1980, but declining supplies of logs from the natural forests resulted in a decline in plywood production. The plantation area of Araucaria cunninghamii is largest in Australia, amounting to 45,000 ha with a timber production of 350,000 m³ in 2002. In 2001 about 1000 m³ of Araucaria plywood was exported from Papua New Guinea, at an average price of US$ 372/m³. The timber from African plantations is only used locally.
The heartwood is pale yellowish brown, occasionally with a pinkish tinge and not sharply demarcated from the straw-coloured sapwood, which may be up to 15 cm thick. The wood is lightweight and soft. It has a natural sheen and lustre. The density is about 530 kg/m³ at 12% moisture content. The grain is straight, texture fine and even.
At 12% moisture content, the modulus of rupture is 82–90 N/mm², modulus of elasticity 8920–13,000 N/mm², compression parallel to grain 39–49 N/mm², shear 9 N/mm², cleavage 39 N/mm radial and 56 N/mm tangential, Janka side hardness 3200–4230 N and Janka end hardness 5430–5910 N.
The rate of shrinkage is small, from green to 12% moisture content 2.2% radial and 3.8% tangential. The timber seasons satisfactorily with little or no degrade, although precautions must be taken to prevent blue stain. The wood is easy to work with hand and machine tools, it finishes well and takes paint, stains, varnishes and lacquers uniformly without requiring the use of a filler. It nails and glues well, and it is easy to peel, making excellent veneer and plywood.
The wood is considered to be non-durable in contact with the ground and is susceptible to termite, pinhole borer and marine borer attack. It is reportedly variable in its resistance to impregnation.
The major constituents of the essential oil obtained from the leaves of Araucaria cunninghamii grown in south-western Nigeria were α-pinene (14.8%), terpinen-4-ol (14.7%), shyobunol (8.9%) and spathulenol (8.8%).
- Large evergreen tree up to 60(–70) m tall; bole straight, cylindrical, branchless for up to 45 m high and up to 200 cm in diameter; bark reddish brown to blackish brown, transversally wrinkled, fissured, ridged or plate-like, peeling either horizontally or in slabs; branches in whorls, horizontally displayed, with upcurved tips.
- Leaves arranged spirally, crowded, simple and entire, sessile and broadly attached, lanceolate to triangular, curved, pointed at apex, many-veined.
- Cones unisexual; male cones up to 8 cm long, hanging; female cones 6–10 cm × 5–8 cm when mature and later disintegrating, with spiny, winged cone scales, each scale with 1 ovule partly fused with it.
- Seed triangular, 2–3 cm × 1 cm excluding the membraneous wings.
- Seedling with epigeal germination.
Other botanical information
Araucaria comprises 19 species and occurs in New Guinea, eastern Australia, some islands of the Pacific Ocean and South America. New Caledonia is richest in species (13).
Araucaria hunsteinii and angustifolia
Araucaria hunsteinii K.Schum., originating from New Guinea, and Araucaria angustifolia (Bertol.) Kuntze from South America have been planted in experimental plantations in Uganda. Some species are occasionally planted in tropical Africa as ornamentals, e.g. Araucaria columnaris Hook. and Araucaria heterophylla (Salisb.) Franco, in addition to Araucaria cunninghamii.
Trees of Araucaria cunninghamii usually start bearing cones at 15–25 years of age. Female cones take about 2 years to ripen after pollination. The winged seeds are dispersed by wind. Juvenile growth is generally slow, but trees may reach a height of 33 m and a bole diameter of 42 cm in 30 years. In Congo 12-year-old trees planted at a density of 1000 trees/ha had an average height of 18.5–20.5 m, and an average diameter at breast height of 20 cm. The average annual volume increment in plantations in Papua New Guinea and Australia is 11–14 m³/ha, but in successful plantations 20–30 m³/ha can be reached.
Under natural conditions in New Guinea and Australia, Araucaria cunninghamii is most common above 1000 m altitude (up to 2750 m) in areas with high rainfall and a temperature range of 9–26°C. It occurs on a variety of rainforest soils, from acid to neutral. Araucaria cunninghamii can tolerate mild occasional frosts, but does not tolerate fire.
Araucaria cunninghamii can be propagated by seed sown in beds of well-rotted sawdust or friable sandy loam, under 70–90% shade. Pre-germination and tubing as well as direct sowing may be feasible. To obtain the seeds, cones are collected before they disintegrate on the trees. Cones that do not disintegrate within 10 days of harvesting are immature. Often, less than 1% of the seeds collected from a tree are viable. Filled and unfilled seeds may be separated by flotation. The 1000-seed weight is 330–500 g. Fresh viable seeds give up to 90% germination. The seeds can be stored for a few years at temperatures below 3°C. The seeds can also be dried to 2% moisture content without damage and be kept at temperatures of –18°C or lower, resulting in a viability of about 75% after 6 years of storage. In-vitro propagation has been practised successfully. Stem segments with 3–5 leaf axils, excised from the upper portion of the main stem of 2-year-old seedlings, produce orthotropic buds from the concealed axillary meristems when cultured on a medium of half-strength Murashige and Skoog inorganic salts. Up to 80% rooting is obtained, and after 2 weeks the plantlets can be transferred to a mixture of peat and perlite and maintained at a relative humidity of 90–95%. The young plants are subsequently transferred to normal greenhouse conditions and then to the field, with less than 5% mortality. Inoculation for mycorrhiza formation is necessary. Seedlings reach plantable size in 18–24 months. When planted out into the field, spacing is usually 3 m × 3 m, but wider spacings of up to 7 m × 7 m have also been practised.
The main form of planting is in monoculture plantations. Underplanting in Pinus plantations has been tried with varying results. Weed control during juvenile stages is essential and the plants respond well to fertilizers. Pruning is usually first done when the trees are about 6 years old. In a 35-year-old plantation about 100 stems per ha are maintained. A height of 30 m and a bole diameter of 50 cm are considered satisfactory in plantations in Australia; this requires a rotation of 50–60 years on good sites. The most significant fungal disease of plantation-grown Araucaria cunninghamii in Papua New Guinea and Australia is root and heart rot caused by Phellinus noxius. Armillaria attack has been recorded for plantations in Zimbabwe, and Poria root disease in East Africa. In Papua New Guinea the most serious pests in plantations are the branchlet-mining beetle Hylurdrectonus araucariae and the weevil Vanapa oberthueri. Termites may also cause serious damage. Attacks by groups of fruit bats (Eidolon helvum), stripping the trees of their leaves and bark, have been recorded during long dry seasons in Côte d’Ivoire, resulting in almost complete destruction of 8–12 m tall ornamental Araucaria cunninghamii trees.
The timber is prone to blue stain infection and should be treated with fungicides and removed rapidly from the forest after logging.
In New Guinea large stands of Araucaria cunninghamii have been depleted due to heavy timber exploitation, but a large number of small stands still exist in the wild. Extensive genetic improvement research has been conducted in Australia and Papua New Guinea, encompassing provenance and progeny trials.
Much is known about propagation and silviculture of Araucaria cunninghamii. Extensive plantations have already been established and they produce large amounts of timber, especially in Australia. In plantations rapid growth is possible, without affecting the wood quality. The results of the experimental plantations in different regions in tropical Africa should be evaluated before a decision can be taken on the economic feasibility of larger-scale plantations.
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- Malagnoux, M. & Gautun, J.C., 1976. Un ennemi des plantations d’Araucaria en Côte-d’Ivoire. Bois et Forêts des Tropiques 165: 35–38.
- Olawore, N.O. & Ogunwande, I.A., 2005. Analysis of the leaf oil of Araucaria cunninghamii Sweet. grown in Nigeria. Journal of Essential Oil Research 17(4): 459–469.
- Takahashi, A., 1978. Compilation of data on the mechanical properties of foreign woods (part 3) Africa. Shimane University, Matsue, Japan, 248 pp.
- Teillier, L., 1988. Dispositif experimental d’éclaircies systématiques sur un peuplement d’Araucaria cunninghamii. Centre Technique Forestier Tropical du Congo (CTFT-Congo), Pointe Noire, Congo. 10 pp.
- R.H.M.J. Lemmens, PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands
Correct citation of this article
Lemmens, R.H.M.J., 2006. Araucaria cunninghamii Aiton ex D.Don. In: Louppe, D., Oteng-Amoako, A.A. & Brink, M. (Editors). PROTA (Plant Resources of Tropical Africa / Ressources végétales de l’Afrique tropicale), Wageningen, Netherlands. Accessed 11 August 2022.
- See the Prota4U database.