Endemic plants: unique to New Zealand
There are more than 600 species of plant that occur above the treeline, and 93% of these are endemic – they are found nowhere else in the world.
There are also many unique plant genera, or groups. In the alpine and subalpine category are Raoulia, Haastia, Hectorella, Dolichoglottis and Leucogenes. Other groups, such as Aciphylla, Anisotome, Brachyglottis, Celmisia, Craspedia and Hebe, have only a few species that are found in other countries.
Where do they grow?
Different types of plant grow in different zones, according to altitude.
The flanks of the major ranges are covered in dense native forest up to the treeline (the forest’s upper limit, around 1,200–1,600 metres), except where it has been destroyed by fire, landslides or other natural events. Beech forests dominate the drier eastern ranges. A blend of conifer, beech and broadleaf trees is more common in wetter areas.
A dense tangle of shrubs grows in a narrow band above the treeline, and at the heads of valleys – especially where there is higher rainfall. Beyond this, or at beech treelines in drier eastern regions, there is often a zone dominated by tall tussock grasses.
Tussock gives way to rock and low-growing cushion plants, and then to herbfields, with exposed rock.
White and yellow flowers
Many native alpine plants have white or, less often, yellow flowers. Even the plant groups that bloom elsewhere in a range of colours (Ranunculus, Myosotis, Gentianella), usually produce white or yellow flowers
The likely explanation is that New Zealand alpine plants were mostly pollinated not by birds but by beetles, flies and moths. These are not attracted by bright colours, so the plants did not evolve to produce colourful flowers.
Kea and rock wrens
The comic and colourful native kea (Nestor notabilis) is the world’s only mountain parrot. The tiny, elusive rock wren (Xenicus gilviventris) is the only New Zealand bird that spends its entire life above the treeline. Both kea and rock wrens are found only in the South Island mountains.
Other endemic animals
Other unusual native animals of New Zealand’s mountains are hard to find. They include:
- several species of large carnivorous land snails (Powelliphanta)
- at least two giant wētā (Deinacrida species)
- the only alpine gecko in the world (the black-eyed gecko of the dry Kaikōura ranges)
- the world’s only alpine cicadas.
Invertebrates are often the most visible animals above the treeline – on warm summer days, the grasslands and herbfields are alive with grasshoppers, moths, beetles and flies.
Impact of introduced animals
Mountain ranges are the main habitat for many animals brought to New Zealand and now living in the wild. Usually found in the dense forests, they also tend to be elusive, even when present in large numbers. Among the larger animals are several species of deer, feral goats and pigs, Austrian chamois and Himalayan tahr (the last two being confined to South Island areas). The smaller animals include mice, Norway rats, ferrets, stoats, weasels, feral cats, Australian brush-tailed possums, rabbits and hares.
All these animals are now classified as pests. Over the past 150 years their ecological impacts have altered the character of New Zealand’s mountains. They have greatly reduced both the diversity and number of native birds. This in turn results in fewer plant seeds being dispersed. The vegetation is further reduced by browsing animals, contributing to erosion. Their impact has been greater than that of floods, snowfalls, landslides, fire, volcanic eruptions and the clearing of forest for farmland over the same period.