Nature

The biodiversity of New Zealand is one of the most unusual on Earth, due to its long isolation from other continental landmasses. It is derived in part from Gondwana, from which it separated 82 million years ago and in part from Australia.

Animals

The animals of New Zealand have a particularly interesting history because, before the arrival of humans, probably less than 1,300 years ago, the country was completely free of mammals, except those that could swim there (seals, sea lions, and, off-shore, whales) or fly there (bats). This meant that all the ecological niches occupied by mammals elsewhere were occupied by either insects or birds, leading to an unusually large number of flightless birds, including the Kiwi, the Moa and the Kakapo. Because of the lack of predators even the bats spend most of their time on the ground. There are also about 60 species of lizard (30 each of gecko and skink), and four species of frog (all rare and endangered). There are no snakes and there is only one venomous spider, the katipo, which is rare and restricted to coastal regions. However, there are many endemic species of insects, including the weta, one species of which may grow as large as a house mouse and is the heaviest insect in the world.

Humans first arrived via the Pacific islands, bringing with them the Polynesian Rat (Kiore) and the domesticated dog. Europeans later brought pigs, ferrets, stoats, mice, rats, dogs, cats, sheep, cattle, and many other mammals. Of these, the rats, ferrets, cats, stoats and dogs have all seriously impacted on the New Zealand fauna, driving many species to extinction. Possums were introduced from Australia for a fur industry, and deer from Europe as game animals, both seriously damaging the forest habitat of many birds.

In recent years, successful efforts have been made to remove possums, rats, ferrets, and other mammals from many offshore islands, large and small, in an effort to return these places to something more closely resembling their original state. An estimated 30 tons of dead possums were removed from Kapiti Island, for example. Similarly, efforts are being made to control such species in selected locations on the mainland. In a further step, in certain mainland reserves mammals are being completely eliminated within predator-proof fences creating ecological islands. Examples are the Karori Wildlife Sanctuary in Wellington City, from which about a ton of dead possums was removed after the installation of a mammal-proof fence, and the Maungatautari Restoration Project.

Plants

The history, climate and geology of New Zealand has created a great deal of diversity in New Zealand's vegetation types. The main two types of forest have been dominated by podocarps and southern beech.

Podocarps (Podocarpaceae), an ancient evergreen gymnosperm family of trees, have changed little in the last 190 million years. Forests dominated by podocarps form a closed canopy with an understory of hardwoods and shrubs. The forests of southern beeches, from the genus Nothofagus, comprise a less diverse habitat, with the beeches of four species dominating the canopy and allowing a single understory. In the north of New Zealand the podocarp forests were dominated by the ancient giant kauri. These trees are amongst the largest in the world, holding the record for the greatest timber volume of any tree. The value of this was not lost on early European settlers, and most of these trees were felled.

The remaining vegetation types in New Zealand are grassland of grass and tussock, usually associated with the subalpine areas, and the low shrublands between grasslands and forests. These shrublands are dominated by daisies, which can become woody and 3m high.

While most of the world's ferns grow in tropical climates, New Zealand hosts an unusual number of ferns for a temperate country. These exhibit a variety of forms, from stereotypical feather-shaped tufted ferns and tree ferns to less typical filmy, leafy and climbing ferns. Both the koru, in the shape of an unfurling fern frond, and the silver fern are widely accepted symbols of New Zealand.