Tane Mahuta: New Zealand's Giant Kauri Tree

Scale and age

Kauri (Agathis australis) are the largest trees by timber volume native to New Zealand and among the most impressive conifers in the world. Tane Mahuta is the largest living specimen measured. Its height of around 51.5 metres is not exceptional by kauri standards — ancient kauri in the forest can be tall — but its trunk volume is unmatched among living trees in the country. The lower trunk, before the first branches, is massive and straight, rising like a column before the canopy opens high above.

Age estimates for Tane Mahuta range widely, from around 1,250 to 2,500 years. The uncertainty is genuine: kauri cannot be cored without damage, so ages are estimated from growth rates, which vary considerably with soil, rainfall, and competition. Even at the conservative end, Tane Mahuta was standing before the Norman conquest of England.

What kauri are

Kauri were once dominant across much of the northern North Island, forming vast forests that produced some of the finest timber on earth — dense, straight-grained, and naturally resistant to moisture. Māori used kauri for canoes and buildings. European settlers logged them almost to extinction between the 1800s and early 1900s, leaving only around four percent of the original kauri forest. What remains — primarily in Waipoua, Waima, and Mataraua forests — is now protected. The trees that survive represent a landscape that once covered much of Northland.

Phytophthora agathidicida

The most serious current threat to kauri — including Tane Mahuta — is kauri dieback disease, caused by the water-mould pathogen Phytophthora agathidicida. It attacks kauri roots, destroying the tissue that absorbs water and nutrients. Infected trees bleed resin from their bark, lose their canopy, and die slowly. There is currently no cure.

The pathogen spreads primarily through contaminated soil, carried on boots, tyres, and animals. All visitors to Waipoua Forest are required to clean their footwear at disinfection stations before and after entering any kauri area. This is not a recommendation — it is a requirement, and it is the primary defence protecting trees that are irreplaceable on any human timescale.