Our land-based environment consists of soil, the rocks which underlie it, and the vegetation that cloaks it. Being urban dwellers, most New Zealanders could be excused for thinking that their use of land extends no further than the backyard. But vast areas of land are needed to produce and distribute the food, fibres, minerals and manufactured items that are so integral to our daily lives. Seen from this perspective, we each 'use' much more land than we think. We all depend to varying degrees on products and services from farms, planted forests, mines, factories, warehouses, shopping centres, schools, offices, roads and landfills-all of which use land. Many of our recreational activities also use substantial areas of land (e.g. sports fields, golf courses, tennis courts, parks and gardens). All these land uses contribute to our well-being and make New Zealand one of the better places to live. But they also have impacts on the environment and on the native species that were once sovereign here.
Taken together, farming, forestry, transport and urban development occupy some 18 million hectares of New Zealand, nearly two-thirds of the total land area (see Table 8.1). This represents about 5 hectares of developed land per person, and a further 2.5 hectares of wilderness. When we look more closely at our 5 hectares of developed land, we can see that 4 hectares are covered in grass and occupied by sheep and cattle.
Scattered over the remaining hectare are all our other forms of land development. Half this is devoted to forestry (mostly exotic pine plantations), a quarter has roads, towns and cities built on it, and the remaining quarter is a patchwork of crops, horticulture, retired farmland, regenerating scrub and private indigenous forest (much of it cut over). When we consider that nearly all of this land was once indigenous forest teeming with unique birds, bats and frogs it is clear that human society has imposed a heavy 'ecological footprint'. We cannot go back and erase that footprint, but we can learn to tread more lightly from here on and, in so doing, recognise how heavy-footed we have been.
The evidence from buried pollen, charcoal, and bones suggests that human impact on New Zealand's vegetation and soils began with the first arrivals about 700-800 years ago (Anderson, 1991; McFadgen et al., 1994; McFadgen, 1994). Pollen analyses from peat bogs around the country reveal that prior to a.d. 1300 forest fires occurred sporadically, ignited by lightning strikes and volcanoes. Then they became frequent and widespread, particularly between 1350 and 1550 (Anderson and McGlone, 1992; McGlone et al., 1994; McGlone et al., 1995; McGlone and Basher, 1995). The remains of more than 30 extinct birds in Māori food middens also attest to a human impact which was sudden and catastrophic (see Chapter 9).
By the time Europeans arrived, the forests had been reduced from about 85 percent of the land area to 53 percent, and the tussock grassland had expanded from about 5 percent to almost 30 percent. The new settlers triggered a new wave of deforestation. Within barely 100 years, the forests had been further reduced to 23 percent of the land area while the grassland had expanded to just over 50 percent. Today, New Zealand has ten times more grassland than it once had, and only a quarter of its original forests. The landscape has been changed beyond recognition from a dark green forest cloak fringed by tussock, duneland and wetland to a light patchwork blanket of pasture, exotic forests, crops, roads and settlements.
International comparisons come naturally to New Zealanders. Being both an island nation and a trading one, we constantly compare our economic performance, sporting achievements, culture, lifestyle and environment to those of other countries. While such comparisons are often made out of context, they do highlight some of the features which make us distinctive. For example, tourists from more crowded or wooded parts of the world often comment on New Zealand's 'open spaces' and the abundance of sheep. Some are surprised to find such a highly modified landscape in a country with such a low population density (13 people per square kilometre compared to the world average of 43).
What they do not realise is that the human impact on New Zealand's environment is magnified by the size of our livestock populations and by the fact that it is cheaper to feed and accommodate these animals on extensive grasslands than on intensively stocked feedlots. For every person, we have 13 sheep and 3 cattle. Although our sheep density fell from 260 to 180 per km2 between 1982 and 1995, and is still falling, it is a dozen times higher than the world's combined sheep and goat density of around 14 per square kilometre (World Resources Institute, 1996). Our cattle density, which has fluctuated around 30 per km2 since the 1960s, and has recently risen to 35 per km2, is more than three times the world average of 10 per km2.
|Land user||Land area|
|Builtupon land (roads, railways, buildings etc.)||.89||3|
|Domesticated land (occupied farm and forest land)||17.30||65|
|Conservation land (national parks, reserves, protected sites)||8.10||30|
|Total New Zealand land area||27.05||100|
Sources: Molloy (1980); Ministry of Forestry (1988, 1994a); Statistics New Zealand (1994a, 1995)
To meet the grazing requirements of all these animals, much more of New Zealand's land surface has been converted to farmland than the world average (51 percent compared to 37 percent). Pasture occupies a greater proportion of our land area (50 percent compared to the world's 25 percent) while crops occupy much less (less than 2 percent compared to the world's 11 percent)-even though 14 percent of New Zealand is capable of growing crops.
This preference for animal production over crop production has deep economic and historical roots and explains much about the New Zealand landscape and our 'ecological footprint' on it. Some of the environmental impacts of pastoral agriculture first became apparent last century, within decades of European settlement. They included:
- reduced native biodiversity (i.e. fewer species and varieties of indigenous plants and animals) caused by the removal of forest and wetland and the arrival of alien predators and competitors;
- reduced pasturage (i.e. edible grass) in tussock grasslands as a result of excessive burning, overgrazing by sheep, infestations of rabbits, and the impact of weeds;
- burial of new pasture under windblown sand dunes destabilised by fire and grazing; and
- damage to farms and settlements caused by erosion in headwater catchments and flooding and siltation on river flats downstream.
Although data on the current extent of these and other land problems are not very precise, this chapter summarises the available information. It describes the nature of our land, the pressures that we impose on it, the state of the soil and vegetation as far as we can assess it, and society's responses to some of the problems that have arisen. The effects of land use on water are discussed more fully in Chapter 7, and the effects on biodiversity in Chapter 9.