Queensland kauri, smooth-bark kauri (Newbury [no date]), kauri pine (Boland et al. 1985).
There are two subspecies, distinguished by distribution and by pollen cone morphology:
Some authorities (Newbury [no date]) segregate the Fraser Island population as A. robusta and refer to the northern populations as A. palmerstonii. (Boland et al. 1985).
Monoecious trees 25-30(-43) m tall and 100-150(-200) cm dbh; trunk straight with little taper, clear for over half its length; crown dense (Newbury [no date]). Bark orange-brown, brown or grey-brown; smooth to slightly flaky. Inner bark mixed red, pink and brown; bark exudate clear or somewhat milky (Boland et al. 1985). Shoots of two types, primary (from the branch) and lateral, diverging from primary shoots. Leaves spirally arranged on primary shoots, opposite to subopposite on lateral shoots; leaves entire on petioles 3-10 mm long, linear to elliptic, 5-13 × 1-4 cm, stiff; veins fine, longitudinal, more or less parallel. Juvenile leaves similar but oblong-lanceolate, acute, 6-7 × 1-2 cm, glabrous, green, shiny above and dull beneath, venation faint and longitudinal. Cotyledons 2, almost sessile, oblong or ovate, 3-4 × 1-1.5 cm; veins fine, indistinct, longitudinal, more or less parallel. Cones globular to cylindric, 9-15 × 8-10.5 cm. Cone scales 340-440, with those from the equatorial section 3.4-4.1 × 3.9-4.6 cm. Pollen cones shortly pedunculate or almost sessile, usually axillary on slender leafy twigs, cylindric, 4-8.5(10) × 0.7-0.9 cm at maturity, bearing 600-1300 microsporophylls, each with 2-8 pollen sacs on the underside. Maturity July-September (Boland et al. 1985). Seeds narrowly cordate, winged. Wood creamy white to pale brown, similar to that of Agathis microstachya but with a density of 435-480 kg m-3. Sapwood and heartwood difficult to distinguish (Newbury [no date], Boland et al. 1985).
Subsp. robusta has mature pollen cones up to 9 mm wide and obtuse-triangular microsporphylls with a raised head, 1×1 mm wide. Subsp. nesophila has mature pollen cones 9-13 mm wide and microsporophyll heads rhombic, not raised, 1.5-2 mm wide (Farjon 2010).
For subspecies robusta:
Australia: found in two disjunct areas, one in S Queensland between Tewantin and Maryborough (mainland) and on Fraser Island [latitude 25°-26.5° S]; the other in N Queensland between the Herbert River and Big Tableland near Cooktown [latitude 15.5°-18.5° S]. You can also create a highly detailed map, and access specimen data, using the "search" function at the Australia Virtual Herbarium.
Queensland kauri grows from near sea level to (in the N) 900 m. The northern distribution is humid tropical; the mean January maximum temperature is 30-32° C and the mean July minimum 13-19° C. The southern distribution is humid subtropical with January and July temperatures of ca. 30-32° C and 6-8° C respectively. Annual precipitation is ca. 1100-1800 mm, summer-wet; rainfall in the driest month (August or September) is 25-35 mm. Soils are deep, well-drained, developed on sand dunes (Fraser Island), basalt, metamorphic or granite rocks; the species develops best on the latter (Boland et al. 1985).
The species grows as a rainforest emergent and is dominant in dry marginal rainforest types. There are many associated rainforest trees, including in the northern part of its range hickory ash (Flindersia ifflaiana), silver ash (F. schottiana), brown tulip oak (Argyrodendron polyandrum), mararie (Pseudoweinmannia lachnocarpa), flame tree (Brachychiton acerifolius), stony backhousia (Backhousia hughesii), cadaga (Eucalyptus torelliana), candle nut (Aleurites moluccana) and Rhodamnia costata. In its southern range, it may be found with silver ash, mararie, flame tree, iron wood (Backhousia myrtifolia), Bennet's ash (Flindersia bennettiana) and brown malletwood (Rhodamnia trinervia) (Boland et al. 1985).
For subspecies nesophila:
The WCMC states that "Scattered emergents survive in small exposed groves of rainforest in the eastern highlands. Over exploitation of the timber is a threat." Based primarily upon risks of land clearance and the known area of occupancy, the IUCN has assigned "Vulnerable" status to this subspecies.
Reportedly, trees 255 cm dbh were measured historically on Fraser Island, but were later cut. The north population has also been heavily logged, but a tree 137 cm dbh and 43 m tall was measured in 2002 on the Skyline Walk above Cairns. Ornamental trees are almost all from the Fraser Island population, and have grown nearly as large as the surviving wild trees. Outstanding examples include:
Due to the absence of datable growth rings (see below), no data are available. Given the size of the species, and by analogy with other species of Agathis, maximum ages could reasonably be expected to exceed 300 years. However, the largest specimens now in cultivation are about 100 years old and are approaching the size of the largest recorded wild specimens, so it is possible that the oldest trees may not exceed 200 years.
"[T]rees growing in a seasonal tropical climate in north Queensland produce latewood during cooler and drier periods. Vascular cambium growth rates fluctuate, and slow-growing trees temporarily have inactive cambium around parts of the trunk so no growth ring is formed. Radiocarbon dates on old Agathis trees indicate that the frequency of ring formation is less than annual" (Ash 1983). As of 2009, no further work is reported on this species.
This tree was first reported in 1842 by Andrew Petrie, who found it growing in the Mary River country. He reported that the native peoples made their nets from its inner bark (McInnes-King 2002).
Historically, "Because of the size of the trunk it was possible to obtain fairly wide boards.Very even texture. Seasons very readily with little movement. Not durable in contact with the ground, but otherwise stands up to exposure quite well. Easy to work and can be finished to a beautiful glossy surface. Stains and polishes well. Uses: Plywood, cabinet work, furniture, indoor fittings, boat building, turning. In early homes was used for kitchen sinks and bench tops, cutting boards, flooring.
"Availability: Almost completely cut out, and does not perform well in plantations" (Newbury [no date]).
Can be seen on Fraser Island. The best stand is said to be near the center of the island, requiring a two-day walk or the hire of a sand vehicle.
Ash, J. 1983. Growth rings in Agathis robusta and Araucaria cunninghamii from tropical Australia. Australian Journal of Botany 31:269-275.
McInnes-King, David. 2002. Tree Dinosaurs. Larnook, Australia: Souvenir Edition.
National Register of Big Trees. 2012. Tree Register: National Registry of Big Trees. www.nationalregisterofbigtrees.com.au, accessed 2012.06.23.
Newbury, Keith. [no date]. WoodLink VWA Homepage. http://home.vicnet.net.au/~woodlink/woodlink.htm.
Last Modified 2017-12-29