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New Zealand's land and environment

New Zealand is a cluster of islands in the South Pacific. Its three largest islands, the North Island, the South Island, and Stewart Island, are much bigger than most that dot the Pacific page of the atlas, and they lie mostly on a north-east by south-west axis. Together, they are more than 1,600 kilometres (km) long but only 450 km across at their widest point. Their combined area is 270,500 square kilometres (km2), or 27 million hectares (ha), about the same size as the British Isles or Japan.

First named Nieeuw Zeeland by a Dutch map- maker some decades after Abel Tasman's 1642 voyage of discovery, the islands did not acquire their collective Māori name, Aotearoa (Land of the Long White Cloud), until this century, though the word was sometimes used earlier to refer to the North Island (Barlow, 1994).

However you look at it, New Zealand is remote. Since parting from the ancient supercontinent of Gondwana 80 million years ago, it charted an independent course which steered away from other landmasses and well out into the Pacific. Its nearest continental neighbours are Australia to the west, Antarctica to the south and South America away over to the east.

New Zealand is often called 'the Shaky Isles'. Beneath its hilly surface are two colliding tectonic plates, the Pacific and Indo-Australian plates. Their first meeting about 135 million years ago is what thrust the New Zealand landmass out of the ocean on the east coast of Gondwana. The plates continue to push and slide against each other, periodically jolting different parts of the country and sending shudders through land and people. The mountainous surface is cracked and fractured by rows of fault lines and is pock-marked in the North Island by several active volcanoes. In the South Island the colliding plates have forced up a high, snow-capped range of mountains, the Southern Alps, which are rising at a rate of about 1 centimetre a year, just enough to compensate for the constant wear and tear of erosion in this high rainfall environment.

The Southern Alps include 18 peaks which tower above 3,000 metres, the highest being Mt Cook at 3,754 metres. The snow and ice from these mountains are carried away by 360 glaciers. The longest, Tasman Glacier, grinds its way for 29 km past the eastern slopes of Mt Cook down towards Lake Pukaki. Shorter, but more accessible glaciers, such as the Fox and Franz Josef, flow to the west and are well-known tourist attractions. Ultimately, the Southern Alps are drained by a series short, swift-flowing rivers on the west coast, and several wide shingle-bedded rivers on the east. The largest of these is the 322 km Clutha, which carries more water than any other river, but is not quite the longest in the land. That honour goes to the North Island's Waikato (425 km) which flows from the vast volcanic crater that holds the country's largest lake, Taupo.

The period of human settlement is now believed to be significantly shorter than the thousand years commonly quoted in popular accounts (see Box 1.3). Recent analysis of radiocarbon dates from archaeological sites suggests that humans have been here for no more than 750 years, give or take a century (i.e. arriving somewhere between a.d. 1150 and a.d. 1350). The first arrivals were Polynesian-speaking settlers who made New Zealand one of the remotest outposts of the 'Polynesian Triangle' (see Figure 1.1). When it was incorporated into the British Empire nearly 160 years ago, New Zealand also became the remotest member of that realm and is still the Commonwealth country furthest from Britain.

Figure 2.1: New Zealand and the Polynesian Triangle.

The Polynesian Triangle stretches from Hawaii at the apex, down to Easter Island, and across past Chatham Island to New Zealand. It includes Tonga, Niue, Samoa, the Cook Islands and the Society Islands.

In Northern Hemisphere terms, New Zealand's location, between latitudes 33° and 47°, would put it in the middle of the Mediterranean Sea or the heartland of the United States. Spain, Turkey, and Japan all lie in roughly the same latitudinal zone on the globe north of the Equator as New Zealand does to the south. The British Isles lie much closer to the North Pole than New Zealand does to the South Pole. Small wonder, then, that although New Zealand is the 'least tropical' of the Pacific islands, the first British immigrants found the climatic conditions more benign than those they had left behind.

The climate of New Zealand reflects both its location and its geography: maritime, temperate, and breezy (some would say windy). The moist breezes blow mainly from the west, swirl up over the mountains, and generate heavy clouds which spill their rain as they rise. As a result, the west coast, particularly of the South Island, is wet and lush; the east coast is drier.

The winters are cool to cold, the summers are warm to hot. In recent years, as the power of the Southern Oscillation (the Pacific Ocean's see-sawing high and low air pressure systems) and the associated El Niño and La Niña weather patterns have become better understood, they have provided explanations for unusually cool summers-or equally unusual warm ones-and the droughts which sometimes parch the east coast of both main islands.

The climate is ideal for agriculture, and to the casual visitor, the country is a land of lush green farms and neatly fenced paddocks full of cows and sheep. Pine forests, big and small, are another, more recent feature. The number of farms and livestock tends to disguise the fact that less than one-quarter of New Zealand is less than 200 metres above sea level. Steep hills or mountain ranges, sometimes brown, bare, and badly eroded, sometimes green and clad in lush native forest, often form a backdrop to the scene.

Almost without exception, the animals and birds seen from the road on a drive through New Zealand, have been introduced and have some link to farming. The indigenous species are more shy. New Zealand parted company with the prehistoric supercontinent, Gondwana, 80 million years ago. This has produced species of plants, animals, and birds that are found nowhere else in the world, and that need either their ancient shadowy forest habitat or their remote windswept coastal rookeries to survive. Most famous among these is the flightless kiwi, a forest-dwelling bird that filled a niche normally occupied by mammals.

Apart from two small bats, that also took to 'walking' rather than flying, there were no mammals in New Zealand. Here, the role of predator fell to birds, such as the New Zealand falcon and the huge Haast's eagle, the latter now extinct along with its main prey, the giant moa. Other unique animals also succumbed to the impact of humans and their introduced species, while some only just survived.

The tuatara, a lizard-like reptile that roamed the islands of emerging New Zealand when dinosaurs ruled the Earth, and the giant tusked weta, an ancient wingless relative of crickets and grasshoppers, are still threatened with extinction. Unique trees, such as the kauri, the kahikatea, and the totara, have survived but their range has been dramatically reduced. In the higher latitudes and altitudes are the southern beech forests which once formed great swathes through the part of Gondwana which united New Zealand, Antarctica, and southern South America.