Karaka (tree) - Ecology

Ecology

The toxicity of the fruit necessitates care when handling. This evergreen tree is a popular place for smaller birds to sleep in during the winter. It is of great value to birds and other fauna, including invertebrates that feed on their fruits and disperse their seeds. The ability to bear fruit in winter gives this plant a very important ecological value, being a good food source for many species, especially birds, at a time which has a shortage of resources. These same fruits are considered toxic to mammalia. The seeds of Karaka also exhibit anitimicrobial activity against S. aureus and E.coli. The pulp of the fruit is edible, although bitter, but the fresh kernels contain the lethal alkaloid poison karakin. Accounts from the 19th century record that extensive processing was used by Māori to convert the kernels to an edible form, and mention that if the processing was not done with the greatest care, poisoning would result with symptoms including violent convulsions and severe muscle spasms which could leave the limbs permanently fixed in contorted positions. Death resulted in a few cases.

Karaka may be easily grown from fresh seed, but cuttings are very difficult to strike. Young plants are frost-tender and sensitive to cold. The tree will often naturalise in suitable habitats. It is common in cultivation and widely available for sale both in New Zealand and in suitable climates elsewhere. It is regarded as a serious pest species in Hawaii for native ecosystems.

On Chatham Islands this tree (local name - kopi) has played distinguished role in the history of Moriori people: the soft bark of these trees has been used for making dendroglyphs. In late 1998 there were remaining 147 known kopi trees with dendroglyphs.