New Zealand

David R. Given³⁸, Alan Saunders³⁹, Dave Towns⁴⁰, Alan Tennyson⁴¹ and Keri Nielson⁴²

New Zealand (Aoteraroa) is the only hotspot that encompasses the entire land area of a developed nation. A piece of Gondwanaland that separated from Australia about 82 million years ago (Sutherland 1999), it now forms an isolated archipelago located some 2 000 km to the southeast of Australia in the southern Pacific Ocean. It covers 270 197 km², with the three main islands, North Island, South Island, and Stewart Island, making up 90% of the land area. Smaller outliers are the Chatham Islands (963 km²) 800 km east of South Island, the Kermadec Islands (34 km²) to the north, and the Subantarctic Islands to the south (including the Bounty Islands, Antipodes Islands, Campbell Island, Snares Islands, Auckland Islands, and Macquarie Island). Also included here are Lord Howe (14.6 km²) and Norfolk (36.8 km²) islands, both Australian territories.

Climate is an important determinant of biotic patterns in New Zealand. The country is strongly influenced by its mid-temperate location, northeast-southwest orientation, and hilly to mountainous topography, with about 75% of the land area above 200-m altitude and reaching a maximum altitude of 3 700 m on Aoraki (Mount Cook). The mountains form a barrier to westerly airflow, resulting in 12 000 mm or more annual rainfall on the western flank of the Southern Alps, one of the highest on Earth, and heavy falls of winter snow. In striking contrast, rainshadow areas east of the Southern Alps can experience as little as 300 mm annually. The Kermadec Islands have a subtropical climate, with warm, moist conditions throughout the year, while the Chatham Islands have a cloudy, humid climate, with cool, wet winters and warm, often dry summers. The southern Subantarctic Islands have a generally windy, cool, temperate-montane climate and relatively low levels of sunshine.

New Zealand's forest ecosystems are greatly depleted, but perhaps the most impressive of those remaining are the forests of giant New Zealand kauri (Agathis australis), which are restricted to the far north of New Zealand, being replaced further south by forests dominated by angiosperms. In the southern part of North Island and on South Island, extensive areas of forest are dominated by Gondwanan gymnosperms of the family Podocarpaceae, by southern beech (Nothofagus), and by various combinations of these with broad-leaved angiosperms. The podocarp and beech-podocarp forests on the western flanks of the Southern Alps are among the most extensive temperate rainforests on Earth. Scrub and shrublands are of widespread occurrence in drier parts of eastern South Island and North Island; they are often floristically rich, with numerous endemic species. With its many offshore islands, New Zealand has a diverse coastal flora with a significant number of coprophilous plants associated with nesting seabirds, penguin rookeries, and sea mammal colonies. Above the timberline, snow grasses (Chionochloa spp.) often dominate, with floristically rich alpine herbfields in wetter sites and on areas of late snow-lie. At higher altitudes, the nival zone is characterized by cushion plants, many of them endemic and including the peculiar and distinctive “vegetable sheep” (Raoulia and Hastia spp.), which are highly compacted shrubs of the family Asteraceae.

New Zealand has relatively low plant species diversity, with 3 400 species (including 2 300 vascular species and 1 100 liverworts and mosses), but high endemism. At least 1 865 vascular plants are endemic (81%) and an additional 220-440 liverworts and mosses (20%-40%), the exact number for the latter not yet having been determined. In addition, of the estimated 390 plant genera, there are about 35 endemic genera. Some of the more interesting plant species on New Zealand include the endemic fern Loxoma cunninghamii, whose closest living relatives are three species of the genus Loxomopsis from Central America, and the pingao sand sedge, belonging to the endemic monotypic genus Desmoschoenus. There is also a single endemic family, the Ixerbaceae, represented by a single species (I. brexiodes).

Vertebrate diversity in New Zealand is low overall, but again, there is high endemism. The number of regularly occurring bird species in New Zealand totals 198, of which 89 are endemic. New Zealand is thought to have the most diverse seabird community in the world, with no fewer than 84 species known to breed there; for example, it is estimated that at least three-quarters of the world's penguins breed in the New Zealand region (D. Towns, unpubl.). A recent staggering development has been the rediscovery of the New Zealand storm petrel (Oceanites maorianus), in waters just off New Zealand's North Island. Birds were seen in January and November of 2003, the first records of this supposedly Extinct species, previously known only from fossil material and three nineteenth-century specimens. New Zealand also has 15 endemic bird genera (of a total of 71) and three endemic extant bird families (Acanthisittidae, Callaeidae, and Apterygidae), a very high number for a country of this size. Among the surviving avian fauna, the flightless, nocturnal kiwis, of which there are three species (Apteryx spp.), are the most famous New Zealand endemics. In addition, three very large parrots are endemic to New Zealand, including the kakapo (Strigops habroptilus, CR), the most unusual of all psittacine birds, and the kea (Nestor notabilis, VU), a large, inquisitive, long-beaked mountain parrot restricted to the mountainous areas of South Island. Indicative of New Zealand's importance for bird conservation is the fact that BirdLife International recognizes five Endemic Bird Areas (EBAs) for this hotspot: North Island; South Island; the subantarctic Auckland Islands; the Chatham Islands to the east of South Island; and Norfolk Island (Stattersfield et al. 1998).

Reptiles are represented by 37 species on New Zealand, and all native species are endemic and, remarkably, five of the six genera represented are endemic. The largest terrestrial reptile in this hotspot is the tuatara (Sphenodon spp.), a member of an endemic order (Sphenodontida), and the only case in which an entire reptilian order is endemic to a single country. It was previously thought that only one species, S. punctatus, existed, but a second species, S. guntheri, has now been recognized. These reptiles, superficially resembling iguana lizards, are the last survivors of a group that lived side by side with the dinosaurs and whose heyday was the Triassic Period some 200 million years ago (May 1990).

Amphibians and mammals are the two groups of terrestrial vertebrates that are poorly represented. There are only four native frog species, all highly primitive and members of an endemic family, Leiopelmatidae, and genus, Leiopelma, found only on New Zealand. Native mammals on New Zealand number only two, both of them endemic bats, but one, the New Zealand lesser short-tailed bat (Mystacina tuberculata, VU), is the only living representative of an endemic family, Mystacinidae.

The hotspot harbors one of the smallest but most distinctive inland fish faunas of any hotspot, with 39 species in 15 genera, and 25 endemic species. This fauna is dominated by members of the family Galaxiidae, a group of coolwater trout-like fishes restricted to the southern tips of South America, Africa, Australia, New Zealand, and a few small islands such as Lord Howe and the Campbell Islands. Of the 51 galaxiid species known worldwide, 19 occur in the hotspot and 16 are restricted to it. A related family, the Retropinnidae or New Zealand smelts, is represented in the hotspot by three endemic species including the only member of the endemic genus Stokellia.

A distinctive element of the New Zealand biota is the widespread occurrence of gigantism (Daugherty et al. 1993). Some of the giant forms include the now extinct flightless moas and Haast's eagle among the birds, and also giant insects, myriapods, flatworms, land snails, centipedes, slugs, earthworms, and some plants. The world's heaviest insect, the weta or wingless cricket of Little Barrier Island (Hauturu) weighs up to 70 g and is one of 12 species of Deinacrida, the ancestors of which roamed the Jurassic forests.

However, this biodiversity represents only a small percentage of what existed prior to human settlement on these islands. As is the case with many oceanic islands, humans arrived fairly late on New Zealand, with the Maoris first arriving perhaps 700-800 years ago (Ministry for the Environment 1997) and the Europeans in the early part of the nineteenth century. Since then, remarkable species like the giant moas (which reached nearly 3 m in height) and the immense Haast's eagle that preyed on the moas, have gone extinct. Human impact on the pristine ecosystems of New Zealand can be divided into three main categories: predation through hunting, fishing, and gathering; habitat destruction through deforestation, wetland drainage, and ecosystem degradation of various kinds; and, particularly, introduction of alien species, both plant and animal. Since European settlement alone, some 16 land birds, one native bat species, one fish, at least a dozen invertebrates and 10 plants are believed to have gone extinct, while other species such as the tuataras, the stitchbird (Notiomystis cincta, VU), and the North Island saddleback (Philesturnus carunculatus rufusater) survive only on offshore islands.

Furthermore, prior to the arrival of humans in New Zealand, indigenous forest covered some 230 000 km², or about 85% of the country, with the remainder being native grasslands, duneland ecosystems, and wetlands. Today, the forest has been reduced to 62 000 km², or about 23% of the country, and only about 35 000 km² (13%) of this is still in more or less pristine condition. Grasslands, on the other hand, have now increased from 10 000–20 000 km² to more than 140 000 km², or 52% of the country; however, most of this is grazed or overgrown with introduced grasses, leaving only about 15 000 km² in more or less pristine condition. Duneland ecosystems, one of the most threatened ecosystem types in the country, are now down to no more than 250 km². Wetland systems have been especially heavily impacted; once covering perhaps as much as 10 000 km², or almost 4% of the country, they have now been substantially reduced in extent, with only about 4 000 km² still remaining in good condition. In terms of natural habitat, then, it is estimated that remaining indigenous habitat in more or less primary condition amounts to 35 000 km² of forest, 15 000 km² of native grassland-scrub, 4 000 km² of wetlands and other aquatic systems, 2 600 km² of smaller island ecosystems, 1 800 km² of alpine systems, and about 1 000 km² of coastal systems, for a total of 59 400 km² (or 22% of the land surface of the country).

The protected area network of the New Zealand Hotspot includes 3 345 protected areas in IUCN categories I to IV, covering around 22% of the hotspot. The additional protected areas in IUCN categories V and VI bring the total surface area of the hotspot under a reasonable level of protection to 27%, a very high percentage by international standards. Comparing this figure with the 59 400 km² estimated above to remain in more or less pristine condition, it is likely that much of what is left intact in New Zealand is already under some form of protection. In part, this is because a lot of New Zealand is mountainous, and areas like the Southern Alps are protected because the land can't be used for anything else; lowlands, on the other hand, are not nearly as well protected. At least 60 protected areas have been set aside as Nature Reserves or Wildlife Sanctuaries specifically to protect threatened species. These include many of the offshore and outlying islands ranging from the large subantarctic Auckland and Campbell Island groups, Little Barrier (Hauturu), and Kapiti, to the warm temperate Kermadec Islands.

To deal with the incomplete coverage of the country's native ecosystems in the protected area network, several initiatives have been undertaken. For example, one important initiative has been the subdivision of New Zealand into a network of Ecological Regions and Ecological Districts, with subsequent development of rapid survey techniques to assess them. Under the Protected Natural Areas Program (PNAP), these methods aim to identify sites of conservation value which are representative of the study area. The Department of Conservation (which is the main government agency that administers protected areas in New Zealand), local government, and other agencies then begin landowner discussions, with a view to protection. Many landowners are coming to value habitat remnants and rare species, and this opens up an array of possibilities for innovative conservation practices, where the energy and interest of individuals can be combined with the resources of the government and other agencies. Recently, the New Zealand Government has encouraged development of “mainland islands” that are intensively managed, predator-free areas where threatened species can be re-established.

Finally, no discussion on New Zealand would be complete without a word on invasive species, which have contributed to the decline and extinction of many native species in this country. While formal habitat protection is important, active pest management is required if further extinctions are to be avoided. Conservation practitioners in New Zealand have earned an international reputation for their achievements in eradicating invasive mammals from islands and, more recently, controlling animal and plant pests at “mainland” sites. Twelve species of pest mammals and one predatory bird have been successfully eradicated from offshore and oceanic islands in the New Zealand region (Veitch and Bell 1990). Significant recent advances have involved a new capability to eradicate rodents from much larger islands using aerial bait application techniques, and the use of more effective quarantine and contingency procedures to reduce the risks of further invasions. For example, Norway rats (Rattus norvegicus) were recently eradicated from Campbell Island (112 km²), opening the way for important species recovery and ecological restoration objectives. The Department of Conservation is applying a strategy to develop capacity to eradicate different suites of invasive species from further islands and to refine procedures to minimize invasion risks (Cromarty et al. 2002). Important recent progress has also been made in controlling invasive species on the New Zealand “mainland”– sites not surrounded by water, where terrestrial pest invasion rates are higher than on remote islands. Better planned and more consistently supported pest animal and weed control programs have resulted in significant conservation outcomes being recorded (Saunders 2000).

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