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Ecosystems on land include both natural and
modified habitats, and the native species that live there. These can be
inside or outside protected areas like national parks, they can be rural
landscapes and they can be urban towns and cities.Biodiversity on land
has two parts – native biodiversity and
introduced biodiversity.
Native biodiversity
The best guess available is that New Zealand has 70,000 native land-based
species. Only about 30,000 have been described so far. These include:
- 3080 plants
- 5800 fungi
- 10,000 insects
- 2600 arachnids (spiders and mites)
- 61 reptiles, and
- 88 birds (land and freshwater)
New Zealand’s indigenous biodiversity is more primitive than most other
countries, which have flowering plants and many mammals. Instead, New
Zealand’s major species groups are insects and fungi – each of these has a
possible 20,000 species. Plants and large animals make up barely 3700 of the
land-based species and we have only two native mammals – tiny bats.
In the past several hundred years New Zealand has lost many of its large
native land animals. Nearly 1000 animals, plants and fungi are considered
threatened. New Zealand has a greater percentage of threatened
endemic birds than almost any other country – 37 out of 50 species of
land and freshwater species are now threatened.
More information is available here
about the present condition and threats facing New Zealand’s native
biodiversity.
Introduced biodiversity
Many species introduced from other countries add to the overall biodiversity
of New Zealand. This includes 33 mammals, 33 birds, one lizard, three frogs,
20 freshwater fish, about 1000 invertebrates and about 6000 plants. Nearly
2000 exotic plants now thrive in the wild.
New Zealand’s primary production depends almost entirely on introduced
species – in agriculture, horticulture and forestry. About 25 animals and
120 plants are commercially farmed or cultivated. New Zealand has:
- The highest number of introduced mammals of any country in the world
- The second highest number of introduced birds, and
- More introduced species of
vascular plants (these contain
vessels which conduct fluids, unlike mosses and liverworts) in the wild
than original native species
While some introduced species now are, or could become pests and weeds,
others play a valuable role in ecosystems that have been changed, or where
native species have been lost. Examples include:
- Gorse scrub acts as a nursery for native plant seedlings
- Banksia and tree lucerne provide a food source for native birds, and
- Some introduced birds disperse native plant seeds
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