Agathis robusta

Common name: Kauri pine

Other common names: Dundathu pine, Queensland kauri, Smooth bark kauri

Description

Kauri Pine is a large conifer from Australia and Papua New Guinea producing valuable timber. There are two known varieties, one originating from each native country.

The natural range of the Australian variety is limited to small areas on the subtropical east coast and hilly areas in the tropical north of the continent, while the Papua New Guinean variety is found in upland areas in the east of the country.

In its natural habitat, it may reach heights of up to 40 m (130 ft), with a straight round and uniform trunk approaching 2.5 m (8.2 ft) in diameter and without buttresses at the base. The bark is grey and smooth but flakes off in small patches that exposes orange-brown underbark, creating a mottled surface.

Branching starts near the ground on young trees, with the branches steeply ascending and in close to the trunk, resulting in a columnar shape. As the tree grows the lower branches naturally prune off, leaving a mostly branch-free trunk topped with a narrow crown.  

The leaves come in juvenile and adult forms but are generally oval, pale yellow-green when young becoming dark green, thick and leathery with age. They are arranged in pairs along the branches and remind more of the leaves of a tropical hardwood species than those of a conifer. 

The fruit are a round to egg-shaped cone, comparable in size to an orange and are either female or male on the same tree. Only female cones produce seed, which are winged and get carried on the wind after they are released. They mature around sixteen months after pollination then release their seed while still on the tree.

Use

Kauri Pine produces a light- to medium-weight wood, averaging out at 400 to 500 kgs per cubic meter (25 to 31 lbs per cubic ft), with low natural resistance to rot and decay, making it a non-durable softwood.

Suitable logs are sawn into planks for making light furniture, cabinets and other interior joinery, as well as wooden boxes and crates. Small diameter logs are mostly processed into pulp for making paper and products thereof.

The inner bark exudes a clear white resin that slowly hardens on exposure to the air. Once hardened it can be harvested and, similar to other Agathis resins, has turpentine-like properties that in the past led to its use in the manufacture of paints and varnishes.

It is an impressive tree that stands out from its surroundings with its large size, handsome uniform shape and eye-catching bark and foliage. It is best suited to large gardens and parks where its growth will not be restricted.

Climate

Grows naturally in humid subtropical and tropical climates, generally areas with annual lows of 10 to 20 °C, annual highs of 19 to 32 °C, annual rainfall of 700 to 5000 mm and a dry season of 7 months or less. However, trees reach their best development in areas with annual rainfall of 1200 mm or more.

How to grow

New plants are usually started from seed, which the female cone releases when mature.

Performs best on deep, free-draining clay-loam, loam, sandy-loam and loamy-sand soils of a moderately acid to alkaline nature, generally with a pH of 5.0 to 8.0 and on sites with full to partial sun exposure. It has good tolerance to light salt spray and strong winds.

Problem features

There does not appear to be any record of it as a serious weed anywhere in the world and it is assessed as a low weed risk species for Hawaii by the Hawaii Pacific Weed Risk Assessment project (HPWRA).

Where it will grow

With irrigation or groundwater

References

Books

  • Barwick, M., et al. 2004, Tropical & subtropical trees : a worldwide encyclopaedic guide, Thames and Hudson, London

  • Boland, D. & Brooker, I. & McDonald, M. W. 2006, Forest trees of Australia, 5th ed., CSIRO Publishing (Ensis), Melbourne

  • C.A.B. International 2013, The CABI encyclopedia of forest trees, CABI Publishing, Wallingford, Oxfordshire

  • Chudnoff, M. 1984, Tropical timbers of the world, Forest Service, U.S. Department of Agriculture (USDA), Washington, D.C.

  • Francis, J. K. 1998, Tree species for planting in forest, rural, and urban areas of Puerto Rico, U.S. Department of Agriculture, Forest Service, International Institute of Tropical Forestry, Piedras, Puerto Rico

  • Francis, J. K. and Liogier, H. A. 1991, Naturalized exotic tree species in Puerto Rico, General technical report SO-82, USDA Forest Service, Southern Forest Experiment Station, New Orleans

  • Francis, J. K. et al. 2000, Silvics of Native and Exotic Trees of Puerto Rico and the Caribbean Islands, Technical Report IITF-15, USDA Forest Service, Rio Piedras, Puerto Rico

  • Howes, F. N. 1949, Vegetable gums and resins, Chronica Botanica Company, Waltham, Massachusetts

  • Krishen, P. 2006, Trees of Delhi : a field guide, Dorling Kindersley Publishers, Delhi

  • Little, E. L. 1974, Trees of Puerto Rico and the Virgin Islands, Vol. 2, United States Department of Agriculture (USDA), Washington D.C.

  • Luna, R. K 1996, Plantation trees, International Book Distributors, Dehradun, Uttarakhand

  • Macmillan, H. F. 1943, Tropical planting and gardening : with special reference to Ceylon, 5th ed, Macmillan Publishing, London

  • Peate, N. & Macdonald, G. & Talbot, A. 2006, Grow what where : over 3,000 Australian native plants for every situation, special use and problem area, 3rd ed., Bloomings Books, Richmond, Victoria, Australia

  • Porter, T. 2012, Wood : identification & use, Compact edition, Guild of Master Craftsman Publications, Lewes, East Sussex

  • Randall, R. P. 2002, A global compendium of weeds, R.G. and F.J. Richardson Press, Melbourne

  • Rauch, F. D. & Weissich, P. R. 2000, Plants for tropical landscapes : a gardener's guide, University of Hawaii Press, Honolulu

  • Rowell, R. J. 1996, Ornamental conifers for Australian gardens, New South Wales University Press, Kensington, New South Wales

  • Streets, R. J & Troup, R. S. 1962, Exotic forest trees in the British Commonwealth, Oxford University Press, Oxford, England

  • West, A. P. & Brown, W. H. 1920, Philippine resins, gums, seed oils, and essential oils, Bureau of printing, Department of Agriculture and Natural Resources, Manila

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