About Agathis robusta (C.Moore ex F.Muell.) F.M.Bailey
Agathis robusta, commonly known as Queensland kauri, is a large evergreen tree. It typically has a straight, cylindrical trunk, usually reaching 30–40 m (98–131 ft) in height, and occasionally growing as tall as 50 m (160 ft). At breast height (DBH), the trunk diameter is usually around 1.2 m (3 ft 11 in), and may occasionally reach 3 m (9.8 ft). The tree's bark ranges in color from orange-brown to grey-brown; it is smooth but sheds in large flakes. Its leaves are linear-elliptic, growing up to 13 cm (5.1 in) long and 4 cm (1.6 in) wide. The leaves have many fine parallel veins and no midrib, and are borne on petioles 3 to 10 mm (0.1 to 0.4 in) long. Leaves are arranged in opposite pairs on the stem, and rarely form whorls of three. The tree produces globose, green seed cones that are 8–13 cm (3.1–5.1 in) in diameter, with up to 440 scales. These cones mature 18–20 months after pollination, and disintegrate at maturity to release their seeds. Male pollen cones are cylindrical, measuring 5–10 cm (2.0–3.9 in) long and 9 mm (0.4 in) in diameter.
Agathis robusta is found in three separate distinct locations. The first is a southern population in southeast Queensland, occurring around Gympie, Maryborough, and K'gari (Fraser Island). The second is a population in northeast Queensland, ranging from Ingham to Cooktown, including the Atherton Tablelands. The third population is located in New Guinea. The north Queensland population was previously classified as the separate species Agathis palmerstonii, but is now considered the same species as the southern Queensland grouping. This species grows in rainforest on well-drained soils of various types, occurring at elevations up to 1,100 m (3,600 ft) in areas with annual rainfall between 1,100 and 2,000 mm (43 and 79 in).
Sulphur-crested cockatoos (Cacatua galerita) eat the seeds of Queensland kauri. This tree produces high-quality timber that was historically used for a range of purposes, including cabinetmaking, joinery, framing, and plywood. Demand for its timber led to heavy logging starting in the mid-19th century. As a result, the large stands of Agathis robusta that were once common are no longer present, though many individual trees still survive. Logging in north Queensland continued until the Wet Tropics of Queensland World Heritage area was established in 1987.
In the first half of the 20th century, state-owned plantations of this kauri were established in both northern and southern Queensland. These plantations had varying degrees of success, and today only a little over 100 ha (250 acres) of plantation-grown Queensland kauri remains. More than 80 individual trees have been planted along streets and in parks in Cairns. A long avenue of mature Agathis robusta, planted in the 1930s, is maintained at Paronella Park, a heritage-listed tourist attraction in North Queensland.
