Agathis australis

Cultivation Details

Agathis australis is only hardy in the warmer regions of the temperate zone. When dormant it can tolerate occasional short-lived temperatures falling to around -7°c^[1]. Prefers a deep, fertile, well-drained soil in full sun or light shade^[2]. Trees begin to bear fertile seed when around 25 - 30 years old^[1]. Young kauri trees are known as "rickers". They persist in this juvenile form for fifty years or more and can attain a considerable height with their tall thin trunks and narrow pyramid shaped crowns^[1] Kauri trees are rather slow growing over their life span although young trees have been recorded as growing at the rate of 35cm per year^[1]. In even the oldest trees the trunk is kept clean and free of epiphytes by the continuous shedding of small and large flakes of bark which build up in a large mound, 2 metres or more in height, around the base of the tree. This, in time, decays to rich humus and is densely penetrated by the roots of the tree, giving the impression that the tree is growing from it^[1]. The kauri is among the largest trees in the world. A tree known as 'Tane Mahuta' (Maori for 'Lord of the Forest'), in Waipoua Forest Sanctuary is commonly claimed to be the largest in the species. In 2001, it was measured at 45.2 metres tall with a dbh of 491cm; that number is misleading, though, because the base of the tree is buttressed. The main trunk is 17.8 metres tall and contains 255 cubic metres of wood. The total wood volume, including the crown, is much larger. The enormous crown is nearly 35 metres wide and has a dozen branches over 1 metre in diameter, three greater than 2 metres, and one over 3 metres. Adding the wood in the crown brings the total wood volume up to 516.7 cubic metres, making this tree just a bit larger than the largest known Thuja plicata. Thus Agathis australis is the largest tree in the Araucariaceae and the third largest conifer, after Sequoiadendron and Sequoia^[1]. There is an extensive patchwork of buried kauri sites found in Northland, especially in coastal regions behind dunes. The buried logs are being 'harvested' for commercial purposes because the wood is perfectly preserved. Some of the buried trees are enormous, with diameters greater than 3 metres. This wood and associated preserved material, represents an immense store of information about past environments, with some buried wood being radiocarbon dated more than 50,000 years old^[1].