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by  Matt McGlone

New Zealand can be divided into nine broad zones, based on their climate, soils and vegetation. Known as ecoregions, they stretch from the humid north to the chilly subantarctic islands. Their distinctive plant life ranges from lush rainforest, to stands of alpine beech, to tussock grasslands.

Nine ecoregions

What is an ecoregion?

An ecoregion (shorthand for ecological region) is a geographical area. It is defined by features such as climate and soil, which lead to varied plant and animal communities. Ecoregions are a way of mapping areas on an ecological rather than political basis. This enables land managers and conservationists to better understand the areas they manage.

New Zealand’s diverse environments

With its outlying islands, the New Zealand region extends from the subtropical zone in the north (including the Kermadec Islands) to the subantarctic in the south (Campbell Island). Within this national region there are many distinctive areas. This is the result of several factors:

  • a north-south orientation, the three main islands spanning latitudes 34° to 47° south
  • diverse geology
  • mountainous terrain
  • a persistent, moist, westerly windflow.

Methods of classification

There are several methods of classifying ecoregions in New Zealand, from broad to highly detailed. One classification, based on climate, geology and soil, divides the country into 20 regions (based on 800 distinctive environments). Another widely used classification recognises 85 ecological regions and 286 ecological districts.

Nine ecoregions

The ecoregions identified here are broad: six on the mainland and three offshore island regions. They are classified according to climate, geology, landforms and plant cover.

  • The northern islands
  • The northern North Island
  • The Volcanic Plateau
  • The Southern Alps and other axial ranges
  • Windward districts (exposed to westerlies)
  • Leeward districts (protected from westerlies)
  • Central Otago
  • Chatham Islands
  • The southern islands


The distinctive character of life forms in the different regions is due in large part to variations in climate. The north has a warm, moist subtropical climate, while the south is cool and moist. Prevailing westerly winds drop rain on the western coasts as they rise over the main mountain chain. The eastern districts are warmer and drier.

Thoughts of home

Aware of New Zealand’s diversity, journalist Alan Mulgan commented in his autobiography, ‘To a South Islander, New Zealand may suggest first, tussock land and Alps. To me it is primarily an Auckland tidal harbour and a clay cutting near the sea on a hot day, with accompaniment by cicadas.’ 1


The meeting of the Pacific and Australian tectonic plates has created an unstable, fault-splintered zone in central and south-western New Zealand, producing high mountains and a complex range-and-basin topography.

The far north and far south-east of the two main islands of New Zealand are more tectonically stable than much of the country in between. The typical landscape is low, rolling hills.

The small, scattered island groups to the north and south are mainly remnants of basaltic volcanoes. They are important for their marine birds and mammals, and unique land species.

  1. Alan Mulgan, The making of a New Zealander. Wellington: A. H & A. W. Reed, 1958. p. 21. › Back

The northerly islands

Specks in the sea

Off northern New Zealand lie a number of isolated island groups:

  • Norfolk Island (governed by Australia, but closer ecologically to New Zealand)
  • Kermadec Islands
  • Three Kings Islands
  • Poor Knights Islands.


Norfolk Island and the Kermadec group were formed by volcanic eruptions. Both are true oceanic islands (islands rising from the deep sea floor). They are comparatively young: the earliest Norfolk Island rocks date from about 3 million years ago, and the Kermadec Island eruptions from around a million years ago.

The Three Kings rocks date back to the Cretaceous period (around 120 million years ago) and have been separated from the mainland for 10–15 million years.

The Poor Knights are younger – roughly 5 million years old – and have been separated for a much shorter time.

Endemic species

Even as recently as the last glaciation 20,000 years ago, when the sea level was 120 metres lower, all the islands remained isolated. This separation has allowed endemic species to evolve.

Climate and vegetation

All have warm, temperate, moist climates and originally had generally low but dense coastal forest and scrub cover. They share many of these features with coastal Northland.

Pacific and New Zealand links

While representing just a small fraction (75 square kilometres) of the New Zealand landmass, these islands are of great interest to scientists. The offshore islands have been stepping stones between the mainland and the Pacific Islands, their species forming part of an interchange between New Zealand and the tropical Pacific. Some mainland animals and plants, such as the red-flowered rātā (Metrosideros species), have dispersed northward to the Pacific Islands, while species such as hibiscus have dispersed south to New Zealand.

Endemics: species found nowhere else

Norfolk Island has a range of unique species, including:

  • the tall Norfolk Island pine (Araucaria heterophylla)
  • the Norfolk Island palm (Rhopalostylis baueri)
  • a gecko and skink
  • land birds (for example, the Norfolk Island kākā and pigeon) closely related to New Zealand species
  • a number of flightless rails.

The Kermadecs are younger than Norfolk Island, and have been formed by volcanic activity. They have a smaller range of endemic species. This includes a pōhutukawa tree (Metrosideros kermadecensis) and palm (Rhopalostylis baueri var. cheesemanii), and an extinct megapode (a large ground-dwelling bird).

Although the Three Kings are only 53 kilometres north of the mainland, many of their species are endemic – notably the tree Pennantia baylisiana and a single specimen in the wild of the white-flowered vine Tecomanthe speciosa, which is widely cultivated in New Zealand gardens.

The Poor Knights are much closer to the mainland, and have few endemic species, notably the spectacular, red-flowered Poor Knights lily (Xeronema callistemon).

Impact of rats

All the northern islands originally had abundant and diverse marine bird life, especially petrels, but rats have largely wiped them out.

Northern North Island

This ecoregion extends from North Cape as far south as Kāwhia in the west. It curls around the eastern coastal strip to East Cape.

Warm and moist

These northern lowlands of the North Island are surrounded by warm subtropical waters. They enjoy a mild, moist climate with warm summers and few winter frosts. Winters are much wetter than summers, and although there is a regular summer dry spell, severe drought is uncommon.

Rocks and soils

The basement rocks are highly variable, with sedimentary sandstones, mudstones and limestones. However, most prominent ranges, including the mountainous Coromandel Peninsula, have formed from intermittent basaltic and rhyolitic volcanic activity over the past 25 million years. A large part of the west coast is formed from sand dunes.

Compared with most of the country, northern New Zealand is tectonically stable, so the landforms are old. Deep leaching of soils has resulted in clay lying over deeply weathered rock, often bright red because of the high iron oxide content, but lacking essential nutrients. In contrast, soils derived from volcanic rocks are often very fertile.

Species-rich forests

The moist, warm, temperate climate encouraged the growth of the country’s most species-rich and complex forests. Most of New Zealand’s conifer species are found here, including massive kauri trees (Agathis australis). These grow in stands that tower over conifers and broadleaf trees.

A tangle of forest

In An account of New Zealand (1835) the English missionary William Yate described the dense North Island forests:

‘The whole of the earth is completely matted with roots; and those of the smaller trees frequently pass over those of the larger, and seem to draw their sustenation from their more sturdy and gigantic neighbours: and such is the rankness of the foliage, from the ground to the tops of the highest trees, that the eye can penetrate only a few feet before it, into the deep umbrageous recesses of the woods.’ 1

These impressive forests dominated the landscape before being converted to the pasture and scrub typical of Northland today.

Warm coastal bays and inshore islands are covered with broadleaf forest, including large-leaved trees such as kohekohe (Dysoxylum spectabile) and nīkau (Rhopalostylis sapida), New Zealand’s only palm tree.

Endemic species

More than 100 species of trees and shrubs are endemic to this region – they do not grow naturally anywhere else.

Some are abundant in the forest canopy, such as taraire (Beilschmiedia tarairi) and makaka (Ackama rosifolia). Others are just a handful of plants in scattered locations – for example the white-flowered rātā of North Cape (Metrosideros bartletti) and the large-leaved puka (Meryta sinclairi) found on a few headlands and islands.

Many trees have close relatives that are common further south – for example, the northern tawhero (Weinmannia silvicola) gives way to kāmahi (W. racemosa) in the south, and taraire to tawa (Beilschmiedia tawa).


A feature of the northern landscape is its vast gumlands – areas of infertile soil covered with stunted scrub. This is where tracts of kauri forest grew, before humans arrived and lit fires, destroying the forests. Kauri’s acid leaf litter tends to form poor soils.

  1. William Yate, An account of New Zealand and of the formation and progress of the Church Missionary Society’s mission in the northern island. London: R. B. Seely and W. Burnside, 1835, p.18. › Back

Central volcanic plateau

The Ring of Fire

The central North Island is part of the Pacific Ring of Fire – a term used for the rim of the Pacific Ocean, which has earthquakes and active volcanoes.

Volcanic rocks poke through the greywacke sandstone. Volcanoes have been a feature here for many millions of years, and in the north of this ecoregion there are ancient, weathered, volcanic mountains such as Pirongia in the western Waikato.

The current volcanic activity began around 1.6 million years ago, and is driven by the Pacific Plate sliding under the Australian Plate under this area. Volcanism is concentrated in the Taupō Volcanic Zone, which stretches from the Bay of Plenty south to Mt Ruapehu.

Active volcanoes

This is a highly volcanically active area by world standards. It has three frequently erupting cone volcanoes: Whakaari (White Island), Tongariro/Ngāuruhoe, and Ruapehu. There are also two large calderas – Okataina and Taupō. These are lake-filled hollows that have regularly blasted out huge flows of pumice and ash (ignimbrite). Taupō has erupted 28 times in the last 27,000 years, most recently around 232 CE.

Ruapehu is the tallest North Island mountain, and has the only permanent ice and snow in the North Island. Besides the volcanic peaks, there are greywacke mountains from East Cape down to the Kaimanawa Range, and rugged sandstone and mudstone hill country in the west.

To the west are Mt Taranaki and older, worn-down remnants of volcanoes. Eruptions have spread tephra (volcanic ash) across the landscape. Much of the Taranaki region is cloaked in massive ignimbrite deposits, metres thick, formed from ground-hugging hot-ash flows.


Even outside the main volcanic zone, the soils are mostly formed from volcanic eruptions. The flood plains of Waikato have deposits of recent pumice, and deeply weathered clay soils from older volcanic eruptions. Friable, nutrient-rich soils derive from the andesitic cone mountains such as Taranaki, Tongariro and Ruapehu.

In sharp contrast are the deep, nutrient-poor pumice soils of the major valleys and the shallow, infertile soils of the greywacke ranges.

The taller cone mountains are subject to lahars – vast landslides of volcanic debris. Repeated lahars have helped build broad aprons of coarse deposits around the volcanoes, and create a hummocky landscape.

Mild lowlands, cool uplands

The lowland coastal districts of Bay of Plenty and Taranaki share the mild, moist, winter-wet climate of the Northland ecoregion.

In contrast, the higher volcanic plateau and adjacent mountains are cool and wet. The northern warmth-loving plants gradually give way to more cold-tolerant, southern species. Kauri and many other trees stop growing naturally around latitude 38° south. Others, such as kohekohe, are only found close to the coast.


Before human clearances began, the flood plains were covered with dense forests of kahikatea, rimu and mataī, now reduced to tiny remnants.

On deep pumice soils and lower mountainsides, the main vegetation is conifer–broadleaf forest, with subcanopies of tawa and kāmahi.

Higher up, there is a mixed forest of conifer–broadleaf and beech, and then mountain beech, silver beech and cedar forest dominate. The higher ranges and the taller volcanic peaks have alpine vegetation, mostly dispersed from the older and richer alpine flora of the South Island.

On the Hauraki plains and in the Waikato basin, there are enormous raised bogs dominated by the tall jointed rush (Sporodanthus traversii) and mānuka.

Vast ignimbrite eruptions – the most recent being the Taupō eruption, about 232 CE – have had a permanent effect on life forms. They incinerated all vegetation and formed thick tephra deposits, on which new soils have formed. Tall conifer forest thrived, but many less mobile animal species such as land snails were displaced.

The Southern Alps and other axial ranges

Axial ranges: a chain of mountains

As the Australian Plate to the west collides with the Pacific Plate to the east, they thrust up a chain of tall mountains running the length of New Zealand, from Fiordland northwards to the Volcanic Plateau. This comprises the Southern Alps in the South Island, and the Tararua, Ruahine, Kaweka, Kaimanawa and Raukūmara ranges in the North Island.

The mountains are not old by global standards – they began forming with movement along the Alpine Fault around 10 million years ago. The central Southern Alps may have reached their current height (the peaks are over 3,000 metres high) only two million years ago.


During the coldest period of the last glaciation (about 18,000 years ago), a near continuous field of glaciers extended down the Southern Alps from north-west Nelson to Fiordland. Elsewhere, in the lowlands from Taupō south, treeless vegetation and bare ground dominated.

Glacial erosion has strongly shaped the mountains in the South Island, creating jagged peaks and U-shaped valleys. Rivers draining the glaciers have formed broad gravel and silt terraces.


Greywacke sandstones and schists make up most of the axial ranges although in north-west Nelson and the far south, granites, gneisses and marbles are common.

Soils are usually shallow and of low fertility, leached of nutrients by high rainfall. Soils have formed from the low-nutrient greywacke sandstones that make up most of the mountain ranges.

The mountain environments have been created by a combination of factors: high rainfall, cloudy skies, cool summers, cold winters, shallow soils and plentiful disturbance through earthquake, heavy rain and wind.

A profusion of species

The mountain ecoregion covers almost all land in New Zealand above 800 metres (including the tops of the North Island volcanoes). Most uplands are clad in mountain beech or silver beech forest. Elsewhere there is diverse conifer–broadleaf forest of cedar, tōtara, toatoa, five finger, olearia and dracophyllum.

The upland slopes and valley basins were generally covered by beech forest, predominantly black beech, red beech and mountain beech, although the central Southern Alps were almost entirely free of beech: tōtara, toatoa and cedar were the main forest trees.

Alpine zone

Above the often abrupt beech treeline is a zone of low shrubs. Higher up, tall tussocks give way to herb fields, then bare ground, and then snow and ice. This alpine zone has a spectacular diversity of plants and animals.

Alpine scene

Denis Glover wrote of the Southern Alps in his epic poem ‘Arawata Bill’. The ‘birch’ are beech trees.

‘The mountains send below
Their cold tribute of snow
And the birch makes brown
The rivulets running down.’ 1


Shrubs (hebe, coprosma, dracophyllum and olearia), grasses (chionocloa, poa), rosette herbs (Aciphylla species, celmisia), buttercups, gentians and willow herbs have evolved into a host of different species in different habitats.

Plants with unusual growth forms include the whipcord hebes with their conifer-like scale foliage, and the spiny tussocks of the spaniards (Aciphylla species). There is an array of cushion plants, reaching an extreme form in vast pillows of the vegetable sheep (Haastia pulvinaris).

Peculiar, dark deep-rooting plants grow in the huge shingle slides, known as scree, that are an ancient feature of the mountains.


Insects such as cicadas, cockroaches, grasshoppers and stoneflies have adapted to mountain environments, evolving into many species with different forms. Some animals that are rarely found in the alpine zone elsewhere in the world do occur in New Zealand’s mountains. Examples are the parrot known as the kea (Nestor notabilis) and cicadas. New Zealand’s lizards are more cold-tolerant than those elsewhere, and some geckos and skink species occur at the treeline.

  1. Denis Glover, Enter without knocking: selected poems. Christchurch: Pegasus Press, 1964, p. 81. › Back

Windward districts: to the west

Wind and rain

New Zealand’s prevailing winds are westerlies, which pick up moisture as they blow across the Tasman Sea. As they rise over the mountain ranges that stretch from the centre of the North Island to the far south, they drop rain on the western region, particularly in the South Island. Curling around in the far south across Stewart Island and Southland, the winds create a wet, mild, cloudy environment. Western New Zealand has the highest and most consistent year-round rainfall in the country.

Constant cloudiness moderates the cooler winters of the south, but it also means the summers are not reliably warm.


The western sides of the Southern Alps were covered in glaciers during ice ages. Eroded peaks, glacier-sculpted valleys, loops of moraine (glacier-carried rocks and debris, often enclosing lakes) and outwash plains such as the Mackenzie Basin are common in the South Island.

In the lower North Island, vigorous river action and erosion during ice ages created terraces and fertile plains topped with loess (wind-blown dust).

Rapid uplift of the mountains has created distinctive sea-cut terraces in places from Taranaki to the far south of Fiordland. On the Manawatū plains, sand dunes have penetrated far inland from the coast, creating ridges, hollows, and chains of lakes.


The western lowlands are often dominated by tall forests of rimu and kahikatea. Beneath are kāmahi, Quintinia acutifolia, rātā and tree-fern canopies, with abundant climbers and broad-leaved understorey shrubs and small trees.

Rivers bring silt down to the floodplains, forming fertile soils where swampy kahikatea, flax and cabbage trees grow. Mataī and tōtara stands grow on better drained soils. Terraces and poorly drained plateaus typically have deeply leached, low-nutrient soils, with rimu forests and low forest of silver and pink pine.

In many places rushlands and mānuka scrub grow on open, wet, nutrient-poor sites. Along the shores, the mild coastal climate and persistent cloudiness allow frost-tender species such as the nīkau palm and supplejack vine to grow far south.

Diverse environments

North-west Nelson has lower uplift rates than the mountains further south, and has large outcrops of granite, marble, and limestone. Beech-clad mountains and isolated alpine areas have led to considerable diversity in plants and invertebrates (animals without backbones).

In Fiordland, in the far south, similar rocks and lower tectonic activity have also fostered many unique plant and animal species.

Stewart Island is unusual in that, unlike other southern districts, it lacks beech forest – it is covered in dense, conifer–broadleaf forest. With its cool, moist, cloudy climate and peaty soils, it forms a link to the subantarctic islands.

Marlborough Sounds

The Marlborough Sounds in the north-east of the South Island are deeply indented with drowned valleys and islands, formed by a sinking landscape and rising sea levels at the end of the last glaciation.

The scatter of small islands was once connected to the mainland by low sea levels during the last glaciation. They are now predator-free havens for a number of species, including the lizard-like tuatara and the giant wētā.

Beech forest grows on the weathered uplands, in low-nutrient soils. Below this is coastal broadleaf bush, with warm temperate species such as nīkau, tawa and toatoa.

On D’Urville Island, on patches of toxicity in fertile soil, forest has been replaced by low-growing shrubs and grasses.

The far south

Southern Fiordland, Stewart Island, the Catlins region of Southland, and the subantarctic islands all have mild winters and cool summers.

Plants include silver beech (absent on Stewart Island), kāmahi, rātā, rimu and miro. There are also some large-leaved southern island species such as Olearia lyallii and the spectacular megaherb Stilbocarpa lyallii.

Eastern Southland is not as wet as districts further west. It still has a reliable, evenly distributed rainfall, mild winters and cool summers because of its exposure to regular south-westerly weather. Its rolling, fertile landscape is covered with loess (fine windblown dust). It was once clad with tall conifer–broadleaf forest, but this is now mostly restricted to hilly or mountainous regions.

Bogs, covered with wirerush (Empodisma minus) and mānuka, are a spectacular feature of the river plains, now much reduced by peat mining and drainage.

Leeward districts: to the east

Glaciers and rivers

A central spine of mountains extends from the volcanic plateau in the North Island down to Fiordland. It forms the western boundary of this ecoregion.

Extensive faulting and recent uplift have created parallel lines of young mountains to the east, from Gisborne down to central Canterbury. The mountains consist mainly of greywacke, with extensive limestone and mudstone, especially in Hawke’s Bay and North Canterbury.

Glaciers caused vigorous erosion on the eastern slopes of the mountains. Long, braided rivers have built wide alluvial fans at the foot of the mountains.

Along the eastern slopes of the Southern Alps are a set of spectacular glacial valleys with deep lakes dammed by moraines (ridges of debris carried by glaciers). Fed by the glaciers, braided rivers formed impressive gravel and silt terraces. Wind-blown dust (loess) from the rivers has coated much of the eastern leeward district, and accelerated erosion in the mountains has created deep alluvial plains of gravel and silt.

Eastern regions: dry and sunny

The western mountains intercept the prevailing rain-bearing westerly winds. This creates a rain shadow (an area of reduced rainfall on the leeward side). The climate is much drier and less cloudy than in western areas.

In summer, drought and dry soils are widespread, with frosty, sunny conditions in winter. The low rainfall means fewer nutrients are leached from the soil, which is among the most fertile in the country.

Original vegetation

The lowlands were once covered by conifer forests, dominated by tall mataī, tōtara and miro on well-drained sites and kahikatea on swamplands. Only on the wetter flanks of inland ranges did more moisture-loving trees such as rimu, silver beech, rātā and kāmahi dominate.

Human impact: forest to tussock

In prehistoric times these eastern regions seem to have been the most productive area for moa. Vast moa-bone deposits have been found in swamps and early Māori hunting sites.

Because of low rainfall and frequent drought, the southern zone of this region was largely deforested by Māori fires. Remaining eastern forests in the North Island did not long survive European settlement. As a result, the native plants of eastern areas are now mainly short or tall tussock, mānuka and kānuka.

Māori fires created vast areas of bracken and scrub landscape in the north, and bracken, scrub and tussock covered the landscape in the south. Most of this has since been developed for pasture or forestry although in the inland South Island much pastoral tussock country remains.

Central Otago

Driest, coldest and oldest

Surrounded by mountains, Central Otago is cut off from rain-bearing winds. New Zealand is at its widest here, and an almost continental climate has developed.

Central Otago has the country’s driest conditions, the interior valleys having less than 600 millimetres of rainfall a year. The lowest temperatures occur in this region. Dry, droughty summers and cold winters have produced weakly leached, often stony soils, with a tendency to saltiness.

The region also has some of the oldest landforms in New Zealand – the flat-topped schist mountains are part of an ancient eroded surface that has been uplifted.

Southern drought

The driest places in New Zealand are in the south. Some go for 60 days without rain. In Central Otago, potential evaporation always exceeds precipitation, except in winter. Drought conditions are almost continuous.


Before people arrived, open forests of mataī and tōtara grew in the lowlands. Mountain and silver beech covered the wetter uplands in the west.

The main vegetation cover of the central districts was toatoa, kānuka, kōwhai, and grey scrub dominated by muehlenbeckia, coprosmas and olearias. Because of the high evaporation rate in the valleys, this is the only area of New Zealand where salty flats form. Plants and animals have adapted to this environment.

As in other dry districts of the eastern coast, Māori fires almost completely destroyed the original woody cover. In its place, tall tussock grassland grew near the treeline, with dry tussock grassland on lower mountainsides and in valleys.


Before humans arrived, Central Otago had a diverse range of vertebrates (animals with backbones). Among the birds were numerous moa species, Haast’s eagle, Eyles’s harrier, flightless geese and ducks, kākāpō and takahē. Reptiles included tuatara, skinks and geckos.

Most of these are now extinct or lost from the region, but a wide variety of skinks, geckos and insects remain, especially in rocky areas and patches of native scrub.


The stable, flat-topped mountains are capped with alpine grassland and tundra. On some exposed tops the ground is patterned by frost. Tors – pillars of schist rock up to tens of metres tall – harbour small plants, insects and lizards.

The Chatham Islands

Way out east

The Chatham Islands consist of Chatham Island (the largest), Pitt Island and several smaller islands. They are on the Chatham Rise, an area of continental rocks that once formed part of the New Zealand mainland. The islands have only emerged above sea level in the last 4 million years.


The climate is cool, wet and windy, and the temperature does not vary greatly from summer to winter. On these exposed islands, plants have to withstand powerful, salt-laden winds. Blowing across hundreds of kilometres of ocean, the winds pick up salt spray that can travel far inland.


Chatham Island consists of limestone, basaltic hills and dune sand. Together with associated volcanic islands and stacks, it covers about 950 square kilometres. Peat or peat-derived soils cover 60% of the land, forming domes and a deep blanket cover on the southern plateau.

Endemic species

Life forms on the low-lying, isolated Chatham Island group are closely related to mainland species, and to those on the subantarctic islands to the south. Several species of plants and animals are endemic – they are found nowhere else.


Before human settlement, low broadleaf forest, with a mixture of mainland and endemic trees and shrubs, grew along the coast and on well-drained soils. Drier peat soils had a cover of low scrub, while tall jointed rush (Sporodanthus traversii) and tangle fern (Gleichenia dicarpa) grew in wetter areas.

Many plant types are lacking, notably beeches and conifers. But there are a large number of endemics – mainly island variants of common mainland groups. Perhaps the best known is the blue-flowered, large-leaved herb, the Chatham Island forget-me-not (Myosotidium hortensia).

Fish, birds and insects

The islands are unusual in having an endemic freshwater mudfish, Neochanna rekohua.

Many of the land birds evolved from common mainland birds, including separate species of raven, kākā, four rails, snipe, two ducks, fernbird, bellbird, pigeon, warbler, pipit and robin. All but the last four are extinct. The rails have remarkably well developed beaks – an adaptation to allow them to probe peaty ground. As in all the southern islands there is a variety of seabirds, with many petrels and albatrosses.

The insects, although closely related to those of southern New Zealand, are often flightless and large-bodied.

The southern islands

To the south of the mainland lie scattered groups of small islands (Bounty, Snares, Antipodes, Campbell, Auckland and Macquarie). These are often called the ‘subantarctics’.

Macquarie is an Australian territory, but it is ecologically closer to New Zealand’s subantarctic islands. The southern islands all lie between two oceanic convergences:

  • south of the subtropical convergence, where the warm, salty waters of the northern ocean meet the cooler, fresher waters of the south
  • north of the Antarctic convergence, where the cold southern ocean begins.


The climate is windy and cloudy, with persistent light rain and little sunshine. Although it is humid and cool, temperatures do not vary greatly from summer to winter.

Soils and vegetation

Deep, dry peat soils cover almost the entire landscape. They support forest, scrub, grassland or herbfields. In poorly drained valleys and on plateaus, deep raised bogs have formed, with tussock or cushion bog vegetation.

Varied species

The nutrient-rich waters hold an abundance of krill, squid and fish, and marine mammals and birds that feed on them. These small patches of land are home to some of New Zealand’s most biologically interesting species, such as the New Zealand sea lion (Phocarctos hookeri).

Smaller islands

The Bounty Islands are a small group of granite islets totalling just over one square kilometre. There is no soil and few plants, but a number of endemic marine birds and insects.

The Snares are the remnants of granite outcrops, covered in deep dry peat, scrub and grassland.

Macquarie Island, the furthest south of the group, is an uplifted sliver of ocean-floor basalt. Despite its southern position it was never glaciated. Clothed largely in tussock grassland, herbfield and tundra, it has no woody species.

Larger islands

The remaining three island groups are all mountainous remnants of basalt volcano domes. These have been eroded into sheer sea cliffs on their exposed western sides.

Antipodes Island is dominated by grassland fern, with herbfield higher up, and two species of coprosma (the only woody plants) in sheltered sites.

The Auckland Islands and Campbell Island are mountainous, extensively sculpted by glaciers.

Auckland Island has a tall rātā forest (also home to the southernmost tree fern) on the sheltered side. Higher up, this gives way to scrub, tussock grassland, herbfield and tundra.

Campbell Island is at the southern limit of tree growth at this latitude of the southern hemisphere. The lowlands are dominated by dwarf forests of dracophyllum.

The larger islands have spectacular tussock herbfields on exposed westerly cliffs.

Plant gigantism

Plant species have mostly been dispersed from the New Zealand mainland, and many are common to most islands. However, there are about 60 unique species of shrubs and herbs, including the spectacular large-leaved forms. Their leaves, some up to 50 centimetres across, appear to be specially adapted to harvesting energy from the cool, cloudy, ocean climate.


The islands are home to many sea mammals including southern sea elephants, Hooker’s sea lion and three fur seals.

Marine birds are abundant, with numerous petrel, prion, albatross and penguin species. Many have developed into different species. Most island groups have their own species of shag, rail, duck and parakeet. There are also snipe, tomtits, fernbirds, and pipits that are found nowhere else.

Loss of flight

Many birds and insects are unable to fly, or are poor flyers. For insects, this may be because of the high winds. For birds, it is probably because there were no land predators.

The southern parakeets seem to have become partly carnivorous, eating eggs and scavenging dead birds, or even hunting small petrels.

External links and sources

More suggestions and sources

How to cite this page: Matt McGlone, 'Ecoregions', Te Ara - the Encyclopedia of New Zealand, (accessed 16 June 2024)

Story by Matt McGlone, published 24 September 2007