Agathis australis

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Agathis australis, commonly known as kauri or New Zealand kauri, is a giant conifer in the Araucariaceae family. It mainly grows in the northern part of New Zealand’s North Island, north of about 38°S. It is the largest tree by volume in New Zealand and can reach 40–50 meters tall, with a trunk over 5 meters wide. The bark is smooth, and the leaves are long, narrow, and leathery, arranged in opposite pairs or whorls.

Kauri produces both male and female cones on the same tree. The seed cones are round, and seeds are released when the cones break apart; wind carries the seeds. Trees can begin producing seeds around 50 years old and can live for many centuries, often well over 600 years. In forests, kauri trees reach the emergent layer above the main canopy and can shape the soil around them, creating unique plant communities.

Ecologically, kauri creates acidic, leached soil under its canopy, which helps it compete with faster-growing species. It has a shallow root system that works with mycorrhizal fungi to gather nutrients. After disturbances that open the forest, kauri regenerates best in large light gaps, since it needs plenty of light to grow.

Historically, kauri forests covered large areas of northern New Zealand. From the 19th into the 20th century, large numbers of kauri were logged for timber used in ships, houses, and other structures. By the early 1900s, most of the original forests had been cleared or burned. Today, only small pockets remain, with Waipoua Forest in Northland containing most of the surviving large trees. Other significant stands are in Puketi and Omahuta Forests, the Waitākere Ranges near Auckland, and the Coromandel Peninsula. Famous trees include Tāne Mahuta and Te Matua Ngahere in Waipoua Forest.

Kauri dieback is a serious threat. The disease, caused by Phytophthora agathidicida, attacks the roots and can kill trees. It spreads through soil and can be carried on people’s shoes, animals, and equipment. To slow its spread, authorities urge people to stay on tracks, clean footwear, and avoid damaging kauri roots.

Kauri forests are valuable for biodiversity and carbon storage, making their protection a priority. Today, kauri wood is less commonly used in New Zealand, with most supply coming from other sources, but the tree remains a treasured and iconic part of the country’s natural heritage.