A SPECTACULAR & CHALLENGING ENVIRONMENT
Photo copyright: Norman Mackay
The High Country spans the mountainous backbone of the South Island of New Zealand, stretching from Marlborough to Southland. In Otago and South Canterbury the mountain ranges extend almost to the East Coast.
The High Country is vast: of the 27 million hectares that make up New Zealand, 6 million are in the High Country. About 2.5 million ha is farmed, the remainder is held as conservation land by the government.
Because the High Country was the least productive and the most remote land (due to difficulties in fording rivers and gaining access through gorges), it was the last part of the South Island to be occupied by European settlers.
Geography, climate and land use
The land within the high country varies greatly, from fertile river valleys and fans to cold and relatively infertile mountain tops. The climate is harsh with long winters and often dry summers. More importantly, it is highly variable and unpredictable in any one season.
Plant communities, too, are varied. The mix of species at any one site depends on the interaction of natural factors such as rainfall, aspect, altitude, soil fertility, with farm management factors such as grazing intensity.
To understand the dynamics of high country grasslands, it helps to think of them as falling into three general zones:
Vegetation, soils, climate, aspect and topography influence the design of strategies required to achieve sustainable management in each zone.
High Altitude Zone
This zone is above the natural treeline (the natural upper limit of indigenous tree growth), varying from 900 metres in the south to more than 1200 m further north. Here native plant communities of grasses, herbs and dwarf shrubs are relatively stable, with few introduced species. Much of this land is owned by the Crown and is in Department of Conservation management.
Little of this country has ever been oversown or topdressed. However, in some areas it was heavily stocked during early pastoral history when the lower country deteriorated. Now it is well understood that there is only limited grazing available at this altitude and low intensity grazing in late summer is now the norm. If accidental fires occur, recovery can be good, especially with careful control of grazing.
The high altitude zone has many sites with high erosion potential because of slope steepness, regular earthquakes and the effects of frost, wind and water. These forces have produced some striking features such as shingle slides and screes. For some years it was wrongly believed that grazing and burning had created or accelerated this erosion.
Middle Altitude Zone
As this photo shows, most of the mid-altitude zone will revert back to forest if it is not grazed, or if scrub weed control is lax. Photo copyright: WHAM Media Limited
This zone ends at the treeline and is typified by the landscapes that travellers experience when they drive over Porters Pass, Lindis Pass or the Crown Range. As in the high altitude grasslands, the zone has a fairly short growing season.
The middle altitude zone was once forest, but tall-tussock grasslands and shrublands developed following repeated fires lit by Polynesian moa hunters. After frequent burning and grazing by early pastoralists, many of the tall tussock grasslands were further modified to short tussock grasslands.
For nearly a century from 1850-1950, pastoralists used burning and heavy grazing to prevent reversion to scrub or dense, tall tussock. Degradation that occurred during this period still affects some of this land but, thanks to sophisticated rangeland management techniques developed in the last 60 years, most of it has recovered.
Since the 1950s, high country farmers have increased their overall production while ensuring that the management of middle altitude tussock grasslands is sustainable. As a result this land is probably in the best shape it has been for more than a 100 years.
Increased pasture development and use of fertilisers, especially on flats and fans at lower altitudes (normally below 1000 m), has enabled farmers to ease grazing pressure on native grasslands. Also, in some middle altitude areas, oversowing and topdressing have proved viable, especially with the use of subdivision fencing to ensure good grazing control.
Most of this zone cannot yet be developed economically, but it still provides vital summer feed on many properties, especially in dry years. It also has many management and use options, including opportunities to integrate recreation, conservation and pastoral production. Pasture development in this zone is common at lower altitudes, but much less so close to the treeline.
Tussock grassland in this zone is normally sought by the government during tenure review negotiations, even though it is well represented in the conservation estate.
Merino grazing on the flats near Lake Ohau. Photo copyright: Norman Mackay
This zone is centred on, but not confined to, lower altitude land of easier terrain on terraces, fans and downlands. Wherever soils and climate are suitable, land has been developed by cultivation or oversowing to create improved pasture. On suitable sites, diversification from pastoral farming is increasing, with farm-scale plantation forestry and vineyards popular options.
In pre-Polynesian times this land, apart from river flats and wetlands, was largely in forest and scrub. When Europeans arrived, much of it was in tall tussock, except in drier areas where short grasslands occurred. To prevent them from reverting to scrub or forest, tall tussock grasslands were repeatedly fired by graziers, transforming them to short grasslands.
In drier areas, these grasslands became depleted and weeds replaced grasses, a process aided by rabbit plagues during the Great Depression and again in the 1980s.
Some land in the development zone – especially flats with shallow, stony or poor fertility soils with very low rainfall – is uneconomic to develop, except perhaps with irrigation.
On those lower altitude areas where land is dark, steep, and unsuitable for development, management requirements and systems are similar to those for tussock grassland in the middle altitude zone.
Very few large areas representative of vegetation types from pre-European settlement remain in the development zone. The small remnants of native wooded vegetation in gullies and wetland communities in undrained lowlands are therefore seen as a priority for conservation. Some are now protected on private land under legally-binding covenants.