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Agathis australis Kauri
Kauri is a large tree up to 30m and rarely to 60m. tall. The bole of the trunk may be commonly up to 3m. in diameter and occasionally to 7m. There are many records of trees yielding logs 7m in diameter and 24m. long. The bole is always straight, often branch-free, columnar, with little or no taper.
The bark is ash grey and smooth. Scale in fla kes reveal a brown inner bark. Large mounds of shed bark and litter collect at the base of the trunk. On mature trees the branches become massive up to 800mm in diameter and are deeply impregnated with resins that produce timber of superior lustre and colour. Gnarly burrs can occur. The crown in young trees is narrowly conical and in mature trees massive, fla t topped or fan shaped , spreading to a diameter of 30m. The root system serves the two functions of anchoring the massive structure and feeding the living body. Long lateral roots that usually exceed the mature crown in spread, radiate outwards and from which grow strong peg roots that anchor the tree. Fine lateral roots are prominent on the surface and feed the plant by absorbing the nutrients of the decomposing litter. The leaves of young trees are up to 10cm x 12mm lanceolate and in the open may have reddish brown tint. Adult leaves are smaller to 3.5cm and are blunt tipped.
The male and female flowers and cones are found on the same tree. The female flowers are small, green, spherical and develop into ripe cones in 18 mont hs. The female cones are up to 80mm in diameter, carried at the end of short branches. Kauris natural distribution is no furth er south than latitude 38-a line from Kawhia to Opotiki. Its present distribution to the warm north appears to be the outcome of previous climates. Seedlings can withstand a few degrees of frost. It can be grown, siviculturally, in the extreme south of South Island, displaying growth rates similar to that in the north. It is tolerant of a wide range of soils from swamp, to shallow stony soils of steep hill country or heavy clays. Kauri soils develop podzol profiles as the decaying litter washed with rain secretes acids into the soil. These acidic forests stimulate leaching of soil minerals and the formation of a tough impenetrable dark pan. Soils on which kauri once grew are notoriously difficult for farming. However, these podzolic clays have produced the whitest clays in the world mined at Matauri Bay Whangaroa.
A little before noon Messrs. Williams and Davies walked with me to part of a neighbouring forest, to show me the famous kauri pine. I measured one of the noble trees, and found it thirty one foot in circumference above the roots. There was another close by, which I did not see, thirty three feet; and I heard of one no less than forty feet. These trees are remarkable for their smooth cylindrical boles, which ran up to a height of sixty, and even ninety feet, with a near equal diameter, and without a single branch. The crown of branches at the summit is out of all proportions small to the trunk; and the leaves are likewise small compared with the branches. The forest here was almost composed of the kauri; and the largest trees from the parallelism of their sides, stood up like gigantic columns of wood. Charles Darwin The Voyage of the Beagle Written from Waimate Northland
I recommend the following books on New Zealand native plants
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