Land use in New Zealand has considerable impacts on native ecosystems and soil. Landbased activities, particularly agriculture and transport, also cause atmospheric and water pollution, as described in previous chapters. However, the worst and least recognised land use impact has been on native biodiversity, which has lost an immense amount of habitat to agriculture. Many native species are still declining as a result of this loss (see Chapter 9). Halting the ecological decline is one of the main challenges facing today's land managers, but one that has yet to be fully grasped.
The issues of more immediate concern to land users and local authorities are the serious problems caused by soil and water degradation. Although significant degradation of both soil and water is confined to only a few regions (e.g. Taranaki, Gisborne, Hawke's Bay and Manawatu/Wanganui), moderate impacts occur in all regions and at least one form of significant impact occurs in several regions (see Table 8.8). In some areas the problems have the potential to become worse unless remedial action is taken. Among the more serious issues are:
- the loss of soilstabilising vegetation, not only on hill farms and in tussock country, but in upper catchment indigenous forests, along streams and riverbanks and in coastal dunelands;
- the impacts of pests and weeds in agricultural systems and in natural ecosystems;
- the risk of accelerated erosion and nutrient decline in millions of hectares of North Island hill pasture as a result of deforestation;
- the degradation of soil and tussock cover in the South Island high country through pressure from fire, livestock, pests and weeds;
- the degradation of highly productive, but relatively scarce, 'elite' soils, through urban encroachment and through intensive cropping and grazing which can cause compaction, fertility decline, accelerated acidification and chemical contamination;
- the exposure of degraded farmland to climatic hazards, such as drought and flood, which can seriously exacerbate soil degradation;
- the identification and remediation of existing contaminated sites; and
- the contamination of surface water through pasture runoff containing eroded sediment, faecal matter and nutrients, as well as the contamination of groundwater through leaching of nutrients (see Chapter 7).
The laws, policies and plans for dealing with these issues are still new, as is the economic environment in which the new rules and processes must operate. A key to future improvements will be better information and monitoring systems to tell us both how well we are doing and which problems need more attention. If the land and the organisms living on it are to receive better treatment in the future, we will need better knowledge of their condition and the pressures affecting them.
Many efforts are now underway to achieve this through farm sustainability indicators, regional monitoring programmes, national environmental indicators, a national research strategy, national land cover databases and conservation estate maps.
Information alone, however, will not achieve sustainable land management. Ultimately, the future of our land depends on how the information is used. Although New Zealand's major environmental laws are now rooted in an ethic of environmental sustainability, short term economic motives rather than longer term environmental concerns continue to drive many land management decisions.
The negative aspects of this are visible in degraded hillsides and streams, but there have been environmentally positive outcomes too, such as the reduction in sheep numbers, the conversion and reversion of some marginal farmland to forest cover, and the more effective control of high country rabbits. Recent initiatives by forestry and agricultural organisations suggest that attitudes are changing but we have yet to see whether these will develop into a general 'greening' of the New Zealand landscape. Although the seeds of a new land ethic have been sown, it is probably too early to conclude that they have really taken root.