South Canterbury straddles three climatic zones: the Southern Alps, the Mackenzie Basin, and the downlands and coast.
The Southern Alps receive heavy rainfall from the west, averaging 4,300 millimetres per year. Summers are mild, with maximum temperatures averaging 20°C. In winter there is frost and snow, with maximum average temperatures of 11°C. Annual sunshine hours average 1,530. North-westerly winds prevail.
The Mackenzie Basin is a drier region, in the ‘rain shadow’ of the Southern Alps, with an annual rainfall of 600 millimetres per year. Summers are hot and dry, with maximum temperatures averaging 23°C, sometimes rising into the 30s. Winters are cold and frosty, with some snow and a maximum average temperature of 8°C, but it often falls below zero. Annual sunshine hours average 2,180. North-westerly winds prevail, often becoming hot and dry in summer.
The downlands and coast also have hot summers and cold winters. The maximum average temperature is 22°C in summer and 11°C in winter. The annual rainfall of 575 millimetres per year is one of New Zealand’s lowest. Annual sunshine hours average 1,830. North-east (coastal) winds prevail. The zone is exposed to south-west winds and hot, dry north-west winds.
The highest flowering plants growing in New Zealand are Graham’s buttercup (Ranunculus grahamii), Haast’s hebe (Hebe haastii) and a parahebe (Parahebe birleyi) found at up to 3,000 metres on exposed rocks in Aoraki/Mt Cook National Park. But on the highest rocks of all, on Aoraki/Mt Cook, only lichens and mosses can survive.
By the 19th century, glaciation and Māori fires had severely reduced South Canterbury’s forest cover. The only significant areas of podocarp forest – tōtara, kahikatea and mataī – were at Arowhenua and along the foothills of the interior ranges. Other remnants comprised kōwhai, matipo and similar species. There were small areas of beech and mountain tōtara forest at Aoraki/Mt Cook and along the Ben Ōhau Range.
In the mid-19th century most of South Canterbury was a mosaic of flax, fern, scrub and tussock. Cabbage trees (Cordyline species) were abundant. Early pastoralists burned tussock to promote edible shoots, or re-sowed their land in exotic grasses. Most native vegetation has now been superseded by introduced species. After the milling and fires of early European settlement, no more than pockets of native forest remain. The largest remnant is Peel Forest near Geraldine.
Exotic forestry has never been important in South Canterbury. Planting of the largest exotic forest at Kakahu (2,900 hectares) did not begin until the late 1950s. A widely spread exotic pest is hieracium (hawkweed).
South Canterbury was a habitat for the giant flightless moa, now extinct. In 1895 Kapua (near Waimate) was the scene of a major dig for moa bones. In the 1960s bones were also discovered in the Albury Park swamp.
Today, the main birds that are distinctive to the region live by the rivers. They include the black-fronted tern, wrybill plover and the black-billed gull. There are few forest birds, because of the lack of forest cover. However, restoration projects in Waihī and Conways Bush reserves have increased kererū and bellbird numbers. The kea, the world’s most alpine parrot, is often seen around Aoraki/Mt Cook. The grasshopper-like black alpine wētā, known as the Aoraki/Mt Cook flea, is found above the snowline.
South Canterbury has the only known long-tailed bat population on the South Island’s east coast. They are found from Peel Forest to Ōpihi River. The main population is at Hanging Rock, near Pleasant Point.
Wallaby, tahr and chamois
These species were introduced for sport. Wallabies were released near Waimate in 1874, and are mainly confined to the Hunters Hills. Tahr (thar) and chamois were released in 1904 and 1907 respectively at Aoraki/Mt Cook, and soon spread to other mountain areas. All three are periodically culled to reduce damage to native vegetation.
Heavy rabbit infestations remain a periodic problem, particularly in the Mackenzie Country. In the 1950s rabbits were brought under control with poison, but by the 1980s their numbers had increased again. In the 1990s Mackenzie Country farmers were implicated in the illegal introduction of the rabbit-killing calicivirus. Some rabbits are now immune to the virus.