Ecological history of the high country
When the last Ice Age ended in the high country 12,000 years ago; tall podocarp forest entered lowland and lower montane areas; montane and sub-alpine regions became clothed in beech, montane podocarps and broadleaf species; and areas above the tree line, in sub-alpine scrub and tall tussocks.
The driest areas of Central Otago and the MacKenzie Basin supported scrub conifers, small-leaved shrubs, kowhai and kanuka, with grasslands and herbfields on the driest soils. Mountain totara, silver beech and celery pine formed extensive forests on the wetter, higher slopes of mountains and at the margins.
Within two centuries of Maori occupation, 75 per cent of forest and scrub cover had been destroyed in the high country, in the pursuit of moa and for bracken cultivation.
In drier eastern areas and lowlands, the tall forests were replaced by tall and short tussock grasslands, scrub and fern, and patchy, scrubby forest. Much of the area now regarded as pure tussock grassland was largely covered in shrubs.
Decades of grazing has left a landscape
dominated by unpalatable speargrass
European graziers continued the burning of the high country, this time to encourage fresh, palatable grass shoots, and open up shrublands for grazing. Palatable shrubs, native herbs and grasses suffered from high sheep numbers and rabbit outbreaks. In heavily-grazed areas, the main tussock species declined in stature, vigour and cover.
Pasture grasses, low prostrate weeds such as hieracium, and many invasive weeds have changed dramatically native plant ecologies.
Source: Matt McGlone, Landcare Research.
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