Kauri - ghosts of New Zealand's past

When the super-continents of Gondwanaland and Laurasia graced the Earth there was an ancient hardwood tree (Araucariacites australis ) that grew scattered in the forests which colonised the majority of Gondwanaland a mere 250 million years ago. Today's Kauri (Agathis australis ) evolved from the fossil Araucariacites australis .

The oldest surviving member of Araucariaceae - the Kauri (Agathis australis ) was common throughout the northern region of the North Island of New Zealand when humans arrived around 950 A.D.

This magnificent emergent forest giant, which was once dominating and part of a complicated ecosystem was almost wiped out by settlers and their destructive milling practices in the early twentieth century. Hence the Kauri (Agathis australis) is a conservation dependent species.

A member of the conifer family, Kauri grows in the emergent forest layer north of latitude 38S in general temperatures of 17C. Kauri is a very straight growing first rate timber tree with a beautiful grain and contain more timber in the trunks than the Sequoia tree. Kauri is the largest tree by volume in New Zealand.

Kauri has a smooth bark that continuously flakes to prevent any parasitic vines from attaching to the Kauri thus creating enormous piles of litter on the forest floor. As the Kauri matures it sheds any lower branches to help stop any vines taking hold as well so a mature tree will have 40 - 50 metres of bare trunk (bole) with the branches grouped at the top of the tree.

Leaves

The small leaves of Kauri (Agathis australis) are around 3 - 7 cms long and one cm in width. The leaves are leathery and do not possess a midrib. The leaf arrangement is generally opposing.

Cones

The Kauri (Agathis australis) develops both male and female cones on a single tree, and can be 50 years old before producing globose (round) cones, which are from 5- 7 cms in diameter. After pollination the winged seeds (5 - 8mm long with the wing half as big again) are scattered by means of wind dispersal.

Maori saw that the long clear lengths of trunks could be used for their waka (canoes), and the Kauri gum was burnt, ground up and mixed with animal fat so the dark pigment could be used in the tattooing of Maori moko.

Gum was very flammable so one use was to bind it with flax and use it as a torch when it was ignited.

Fresh gum was also chewed, which would have increased learning ability of the settlers brains and maybe one day they woke up to their destruction of the magnificent Kauri.

When Europeans arrived, they, with their uneducated wisdom, saw Kauri (Agathis australis) as a wasteland and proceeded in felling and milling Kauri for construction, shipbuilding, wall panelling, high-end furniture, railway sleepers, fences, bridges and braces for mines and even tunnels. The density of Kauri timber has been likened to that of Cherry wood.

Gum

In the late nineteenth and early twentieth centuries the semi-fossilised Kauri gum was used in oil varnishes which were manufactured in England. So in the 1890's around 70% of all oil varnishes used Kauri gum, that was harvested mostly from the gum fields in Northland, Coromandel and Auckland. Kauri gum shares a few characteristics with the northern hemisphere fossilised resin, amber.

Kauri gum use to be on the beaches and was picked up as an ornament of sorts by the first European and English settlers. When high quality gum was found to be useful for varnish all the surface gum was gathered, then when that was scarce special gum-digging spears were employed by the gum-diggers.

This gum was sold to the gum merchants who exported the gum in cases manufactured from Kauri wood and exported from Auckland to England with the peak gum market being during 1899. Early Auckland was built on the gum trade, especially from 1850 - 1900.

While the higher quality gum found it's niche, the poorer grades were used in manufacturing linoleum. The lower grade nuts and chips were recovered by laborious hurdy-gurdies (water-filled drums with screens). So the gum supply was pretty well depleted by the time the 1930's arrived which hailed the end of the gum industry due to the development of synthetics for manufacturing varnish and linoleum.

Swamp Kauri is ancient preserved Kauri in salt water marshes and other waterlogged areas. It has been carbon dated to be 50,000 years or older and the trees would have reached at least 1,200 years in age, making them one of the world's oldest. This swamp Kauri is also used for furniture and other items like ornaments.

Because Kauri continually flakes off bark to minimise damage by parasitic plants huge piles of up to two metres of leaf litter is created.

Kauri is one of the largest carbon sinks on the Earth.

Kauri (Agathis australis) has a mutualistic relationship with mycorrhiza which are in the roots of the Kauri. Because of the enormous mounds of slowly decomposing litter (due to waxes and phenols ), Kauri feeds in this organic litter near the soil surface via its fine root hairs.

The Kauri also has deep peg type roots which serve as anchors should windy weather, such as tornados, arrive.

The leaf litter under the mighty Kauri are more acidic than that of other trees and this helps with leaching the soil and starving competitor trees of nutrients. The Kauri changes the soil it grows in to its advantage thereby competing with the faster growing angiosperms.

When the 1800's arrived so did the English and European settlers. They saw the 1,200,000 hectares of Kauri forest as a wasteland and promptly felled it (with the primitive saws of the times) replacing it with pasture.

When the 1877 Land Act was passed Kauri were meant to be protected but due to the ignorance of the times, the Puhipuhi fire that was deliberately lit, burned for seven long years from 1881 - 1889. Kauri fires burn slowly because of the very deep litter beneath them.

1900 - Approximately 300,000 hectares of these magnificent Kauri were left. This from generations of thoughtless destruction and political incompetence, all because the governments pretended to ignore the destruction of the Kauri and its ecosystem that other organisms relied upon.

The destruction of the Kauri Forests has been noted as one of the saddest occasions in botanical....and human history.

Unbelievably, it was 1952 before the logging of Kauri at Waipoua Forest finished, leaving only 80,000 hectares remaining. So as it has been in all countries around the world man does not think of the future. Look at the Brazilian Jungles.

The largest Kauri recorded was in Mercury Bay, Coromandel Peninsula in the North Island. The first branches of this tree were a whopping 22 metres above the ground. It had a height of 23.4 metres (77').

There are several areas where Kauri still remain because the Maori's had not used fire or the area was too inaccessible for European logging. Waipoua Forest is the only remaining forest in virgin condition.

There is a team of scientists and councils working on the Phytophthora taxon Agathis fungus which causes dieback (Kauri Collar Rot). This fungus appeared on Great Barrier Island and the cause of its spread to the mainland of New Zealand is on shoes and animals like feral pigs.