Kauri – Agathis australis
Other Names: agathis
Distinctive Characteristics: Kauris are conifers, with small, leathery evergreen leaves that are elliptical in whorls, with shedding, flakey bark. Mature Kauri trees have characteristically large, massive, columnar trunks with little or no branching below the crown, which is characteristically narrow. Kauris ooze a sticky, resinous gum that protects them from fungi and wood-boring insects. Over time, the gum hardens, falls to the ground, and gets buried. The fossilized gum, or resin, called kâpia, has hardened over millions of years into various grades of beautiful copal, or amber.
Kauris are an ancient species, with ancestors from 190 million years ago. Prehistoric Kauri trees, known as swamp or ancient Kauri, have been preserved in salt marshes and dated to over 45,000 years old, and are still a viable source of preserved wood. Today, the Kauri forest is considered a long-term carbon sink. The total carbon content in living, above-ground biomass and dead biomass of mature Kauri forest is estimated to be nearly 1,000 tons per hectare— the second highest of any forest type recorded anywhere in the world, after Mountain Ash (Eucalyptus regnans).
Distribution: Native to the northwest corner of the north island of New Zealand, north of 38°S latitude from the Kāwhia Harbour in the west to the eastern Kaimai Range, with some patches on Great Barrier Island. Elevation: sea level to 2,000 ft. (600 m).
Ecosystem: Subtropical rainforest, with other trees including Rimu, Tōtara, Taraire, Kohekohe, Miro, Hard Beech, Kahikatea, and Pūriri. Thirty-eight species of ferns, orchids, and other plants were found in just one tree. On the forest floor grow astelia grass and ghania sedge.
Maximum Age: Estimated at 2,000 years.
Maximum Height and Girth: Over 185 ft. (56 m) in height; over 88 ft. (26.83 m) in circumference.
Animal Community: Branches provide habitat for shorttailed bats and birds, including kererū, kākā, kākāriki, and eastern rosellas. Mice eat the seeds. Insects such as the kauri leaf miner moth caterpillar mines the leaves; looper caterpillars, kauri weevils, and native longhorn beetles can be found on the wood.
Medicine: The gum was used to as an insecticide in kumara plantations, as well as for dressing wounds, repelling leeches, and treating asthma and arthritis (Maori).
Food: The fresh gum was used for chewing (Maori).
Tools and Objects: Branch wood was used for making mallets, weapons, and spades. Scrapings of harder gum were used to kindle fire (Maori).
Art and Ceremony: The wood was prized for large carvings. Soot of the burnt gum was used as a tattooing pigment (Maori).
Transportation: The wood was prized for making canoes (Maori).
Modern Uses: Nineteenth-century Europeans exploited most of the accessible old trees, valuing the timber for its branch-free trunk (with tight grain and no knots), using it widely for making ships, houses, carts, furniture, wood paneling, fences, bridges, dams, church pews, post office counters, mine braces, and railroad ties. Stumps and perfectly preserved ancient swamp kauri are used for furniture, fine wood turning, carvings, and tourist trinkets. The fossilized amber- and milky yellow-colored resin was mined extensively and was a valuable commodity (used as money, it was said to have built cities). It was sold in chunks and carved and polished to make beautiful collectibles, and is still sold as jewelry. The resin was also used to make varnish, linoleum, waxes, candles, and molding material.
Threats and Conservation: It is estimated that, today, only 4% of the original, uncut forest remains in small pockets. Even though it was almost logged to extinction, and very few large trees are left, Agathis australis's status is not threatened, while other species in the same genus are. However, Kauri dieback or Kauri collar rot (a Phytophthora disease) is a threat.