The massive kauri tree is part of the ancient Araucariaceae family, consisting of the genera Agathis and Araucaria, that is represented by evergreen trees only in the Southern Hemisphere. The kauri forest exceeds all other New Zealand trees in its antiquity. The genus Agathis evolved from the Araucariacean fossil Araucariacites australis which appeared 190-135 million years ago in Jurassic times and continued until the Oligocene period. The genus Agathis is first dated from fossils in the middle Cretaceous 100 million years ago, and by the Oligocene 30 million years ago it had replaced its Araucariacites australis ancestor.

There are 16 species of the genus Araucaria, which include the well known monkey puzzle tree, A. araucana, found only in Chile; the Norfolk Island pine, A. heterophylla; and the candelabra tree, A. angustifolia from Brazil.

The only member of the Araucariaceae family now native and endemic to New Zealand is Agathis australis. Another 19 Agathis species are native to the Western Pacific countries of Australia, Indonesia, Malaysia, Philippines, New Caledonia, Celebes and Fiji.

They are some of the largest and longest growing trees in the world, with massive straight trunks free of branches to a great height, and huge branches (as large as 6 feet in diameter in A. australis) in the crown. More timber can be cut from a kauri than any tree of similar size, so it has been a popular tree for the timber industry.

The New Zealand kauri is the largest.  Australia's South Queensland kauri, Agathis robusta is very similar to the New Zealand kauri, but does not grow as big.  A large tropical species, A. alba is valued for its timber and gum in Indonesia and Malaysia.

Kauri once covered 1.6 million hectares (4 million acres) in the northern half of the North Island, extending as far south as Raglan on the west coast, and just past Tauranga on the east coast.  There is no indication that they have ever grown naturally in other parts of the country.  After rampant destruction of kauri forests from logging, fire, and clearing for pastural grazing, the area has shrunk to a mere 7,000 hectares (18,000 acres).

SEE Kauri Logging and the Export Industry Kauri timber was the first New Zealand natural resource to be extracted by Europeans, and the first export.

The extent of kauri logging is shown by Kauri Timber Company operations from 1896 to 1903, when 267 million super feet of timber was milled.  This was part of the greatest surge of production that severely depleted forests.  After 1907 production was dramatically reduced.

Young kauri up to 80 years old have a vastly different bark than mature trees.  The trunk of a mature kauri is kept free of epiphytes by continual shedding of thick flakes of bark, which accumulate to form a large mound that eventually decays into a rich humus penetrated by the roots.  Contrary to the clean trunk, the junction of the massive branches can house a mini-ecosystem of epiphytes, lianes, mosses, ferns and insects.

The gigantic proportions of the kauri are shown by the men at the base of the tree shown above. The kauri is revered by the Maori people, who believe it possesses its own spirit, and have named individual large trees.

The largest living kauri is Tane Mahuta or "Lord of the Forest", still standing after 2,100 years in the Waipoua Forest in Northland. Its massive straight column-like trunk has a girth of 13.7 metres (45 feet) which is 4.4 metres (14 ft) in diameter, and is clear of branches up to a height of 18 metres (59 ft).  Tane Mahuta reaches 52 metres (169 ft) in height, and is estimated to contain 245 cubic metres (8,630 cub.ft) of timber. Another big living tree, Te Matua Ngahere or "Father of the Forest", has a wider trunk with a girth of 16.4 metres (54 ft), and a clear trunk up to 10 metres, however it is not as tall - just 30 metres (98 ft).

An extraordinary Northland kauri named Kairaru which was destroyed by fire in the 1880s near Kaihau, was estimated to have lived for 4,000 years. It was three times larger than Tane Mahuta, estimated to have a volume of 450 cub.m (16,000 cub.ft) of commercial lumber. Kairaru would have contained more timber volume than today's largest giant redwoods of California.

The Coromandel Peninsula is another stronghold of kauri, where natural regeneration has been occuring for some time, and where a few large specimens have been spared from fire and milling.  The size of lost kauri giants can be seen above the Kauaeranga Valley east of Thames.  A number of massive stumps, preserved by the durability of kauri, are 6 metres (20 ft) across.

The largest kauri was measured in 1850 at Mill Creek, Mercury Bay on the east coast of the Coromandel Peninsula.  It had a girth of 23.4 metres (77 ft), which is a diameter of 7.45 metres (24.5 ft).  The first branches were 22 metres above the ground.