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Physical geography

Geography

New Zealand – also called Aotearoa New Zealand – consists of two large islands (the North and South Islands) and several smaller islands (such as Stewart Island and the Chatham Islands). It is situated in the southwest Pacific Ocean between 34 degrees and 47 degrees of latitude south (see Figure 2.1).

New Zealand’s land area of about 270,000 km2 (approximately 26,822,000 hectares) is about the same as that of Japan or the United Kingdom. The country’s land mass extends more than 1,600 kilometres (1,000 miles) along its main north-northeast axis.

Our location on the boundary of the Pacific and Indo-Australian tectonic plates has shaped our landforms. The resulting earth movements have produced hilly and mountainous terrain over two-thirds of the land, with frequent earthquakes in most parts of the country and a zone of volcanic and geothermal activity in the central North Island (Ministry for the Environment, 1997).

The terrain, climate, rock type, and vegetation have interacted to produce more than a hundred different soil types. These can be grouped into three main categories: pumice soils (in the central North Island volcanic area); ash soils (common in Taranaki, the Waikato, parts of Northland, and western Southland); and sedimentary soils (on plains, hill country, and coastal areas throughout both main islands). Despite this diversity, New Zealand’s soils are generally low in nutrients because the rocks they come from are geologically young (Ministry for the Environment, 1997).

Figure 2.1: New Zealand’s geography, 2007

This figure shows a map of New Zealand's geography. It identifies all major lakes, rivers, mountains, capes and bays. The majority of lattés are situated in fiordland and the Waikato/Bay of Plenty. Rivers feature right across the country.

Flora and fauna

New Zealand is known for the wealth of its biodiversity, with more than 80,000 species of native animals, plants, and fungi. It is especially rich in bird, insect, and marine life. Although as much as 80 per cent of the country’s biodiversity lives in the marine environment, little is known about many of our marine species.

New Zealand’s early separation from its geographic neighbours, Australia and Antarctica, played a large role in shaping its flora and fauna. Because our native plants and animals developed in isolation for 60 million to 80 million years, many of them are unique.

Among our most notable species are the:

  • kiwi, which lays one of the largest eggs in the world compared with its body size

  • kākāpō, the world’s heaviest and only flightless parrot (Powlesland et al, 2006)

  • kea, one of the world’s only mountain parrots

  • giant wētā, the heaviest insect (Williams, 2001)

  • tuatara, a reptile of prehistoric origins

  • giant kauri tree, which is among the largest in the world and holds the record for the greatest timber volume of any tree.

Tuatara, New Zealand’s reptile of prehistoric origins.

Source: iStockphoto.

While most of the world’s ferns grow in tropical climates, New Zealand hosts an unusually large number of ferns for a temperate country. Primeval trees, mosses, and lichens continue to flourish here, and flightless, ground-dwelling birds have evolved to fill niches that elsewhere in the world would have been taken by mammals. Indeed, New Zealand’s only endemic land-based mammal is the bat, of which we have several species. By comparison with other countries, we have comparatively few native flowering plants and land-based vertebrate animals.

New Zealand’s isolation also means that a high proportion of our species are not found anywhere else on earth. All of our frogs and reptiles, more than 90 per cent of our insects, about 80 per cent of our plants (other than mosses, liverworts, and hornworts), and a quarter of all of our bird species are found only in New Zealand. Forty-four per cent of our known marine species live only in New Zealand waters.

Climate

New Zealand’s climate is influenced strongly by geographic factors. These include:

  • its location in a latitude zone with prevailing westerly winds

  • the large area of surrounding ocean

  • mountain chains that modify weather systems as they move eastward, so that climatic contrasts are much sharper from west to east than they are from north to south

  • tropical weather patterns (that is, storms that start out as tropical cyclones elsewhere can redevelop in the region, bringing warm moisture-laden tropical air that interacts with colder polar air).

As a result of these factors, New Zealand’s weather is more variable than that of larger, continental countries.

The average rainfall experienced in most urban areas is between 600 millimetres and 1.5 metres a year. However, in the mountain ranges, annual rainfall often exceeds 5 metres, and in the Southern Alps, annual rainfall can be more than 10 metres a year.

Regions exposed to weather from the west and southwest experience showery weather, and rain falls in these areas on about half of the days of the year.

The rest of the country experiences much lower rainfall, particularly in eastern areas. Areas in the South Island to the east of the main ranges – Central and North Ōtago and South Canterbury – are the only areas of the country with average rainfalls of less than 600 millimetres, and generally have only about 80 rain days a year. In the North Island, the driest areas are central and southern Hawke’s Bay, the Wairarapa, and Manawatū, where the average rainfall is between 700 millimetres and 1,000 millimetres a year.

Average temperatures at sea level decrease steadily from the north to the south, from about 15°C in the far north of the North Island to about 10°C in the far south of the South Island (MetService, 2007).

Rivers and lakes

Dynamic tectonic movement means New Zealand’s landscape is dominated by mountains: more than three-quarters of our land area is higher than 200 metres above sea level. As a result, steep and fast-flowing stony streams and rivers dissect the landscape. Because New Zealand is relatively narrow (450 kilometres at its widest point), these mountain-fed rivers quickly reach the sea after flowing through narrow and then winding river beds.

Rivers also feed numerous lakes, of which 3,820 are more than 1 hectare in area. Most lakes were formed through volcanic or glacial activity, or after the formation of land barriers (Ministry for the Environment, 2006). Lake Taupō in the North Island is New Zealand's largest lake, with an area of about 62,000 hectares and a maximum depth of 163 metres.

As well as having numerous mountains, lakes, rivers, and geothermal areas, New Zealand has 360 glaciers in the South Island, which carry away snow and ice from the many peaks of the Southern Alps.

Coasts and oceans

Compared with its land area, New Zealand has one of the longest coastlines of any country in the world, at more than 18,000 kilometres (Department of Conservation, 2007).

New Zealand’s Exclusive Economic Zone extends from 12 nautical miles off the coast to 200 nautical miles offshore, an area of 4.4 million km2. This is the sixth largest Exclusive Economic Zone in the world, and forms a marine area that is 14 times bigger than New Zealand’s land area.

New Zealand’s vast marine area contains a diverse range of marine ecosystems, which provide habitats for many species. Scientists have identified almost 16,000 marine species in New Zealand waters, although it is estimated that tens of thousands of species may still be undiscovered (Gordon, 2007).