Ecology and usage
Kauri are a cornerstone of our indigenous forests of the upper North Island.
Kauri are considered a taonga (treasure) by many New Zealanders, particularly Māori, who see the health of kauri as a sign of general well being of the ngahere (forest) and the people.
They are one of the longest-living tree species in the world, as well as the largest. Mature trees have an average diameter of two metres. These giants can live for more than 1000 years, The biggest can reach heights of over 50 metres, with girths of more than 13 metres.
As the third largest conifer in the world, kauri are scientifically important due to their unique biological traits. Kauri are also considered to be ‘ecosystem engineers’, with their presence changing soil environments, providing protection from erosion and flooding and creating environments that sustain indigenous plant life.
The largest kauri alive today is Tāne Mahuta with a diameter of 4.6m and height of 52m. It is estimated to be between 1200 and 2000 years old. One of the largest kauri trees ever recorded was 'Kairaru of Tutamoe' with an estimated diameter of 6.4m and a height of 65m. Unfortunately, Kairaru was destroyed in a fire before 1900.
Kauri are naturally found throughout the upper North Island, in the Northland, Auckland and Waikato regions, and in parts of the Bay of Plenty. If you’re in a natural bush and you’re in the upper North Island, it’s likely you’ll be near a kauri. Kauri have existed as a species for around 20 million years.
The site, soil and temperature determine the type of forest that naturally contains kauri. There is no 'typical kauri forest': kauri can exist as solitary trees in broad leaf dominant bush or as dense stands.
When in a forest environment, mature kauri emerge above the canopy of other native trees. The lower forest can contain a variety of tree species including tōtara, tānekaha, taraire, tawa, miro and rewarewa, alongside juvenile kauri. At the shrub level a range of plant species can be found including tree ferns, nikau palms, lancewood, hangehange and mingimingi. Kauri grass is commonly found covering the ground beneath kauri. A range of orchids and epiphytic plants are also often found perching amongst the branches of mature trees.
Kauri growth requires high light levels but can tolerate low soil nutrient levels. Consequently, kauri seedlings are often suppressed under dense canopies of faster growing species in fertile soils. As a result kauri are often restricted to less fertile soils on ridges or establish en masse after a large disturbance such as a fire.
The plants, animals and ecosystems that kauri create and support are indirectly under threat from kauri dieback disease, as without kauri they cannot live and develop the way they do now.
The use of kauri
Before European settlers arrived in New Zealand, kauri forests covered more than a million hectares of northern New Zealand. Less than 1% of this original kauri forest now remains. Māori used the timber of kauri to build waka – canoes, and kauri gum for a variety of purposes, including as an insecticide and to make torches (Ref: Department of Conservation (n.d). The Science of Kauri Protection. [Brochure])
Early Europeans recognised the value of kauri due to its high-quality timber. A kauri timber industry developed in the 1820s and grew significantly through the mid-1800s, with large quantities of kauri timber and gum used domestically and exported. By the 1930s most kauri forest had been logged and only a few patches of mature kauri remained.