Threats to biodiversity

Biodiversity in the Waitaki District is undergoing a significant decline. For example, between 1998 and 2008 the Waitaki District had a higher rate of tall tussock loss than any other district in New Zealand, and the rate appears to be increasing (Weeks et al 2012).

Other significant ecosystems are almost gone. For example, native forest and scrub now covers only ~38,000 ha (5%) of the Waitaki District, and much of the river plains in the district have less than 5% indigenous vegetation cover remaining.

As the remaining patches of tussock and bush get smaller they also tend to get overrun with weeds and pest animals like possums, rabbits and hares that eat native plants and animals. Animal pests can also introduce weed species like blackberry, banana passionfruit and hawthorn. Often these plants can grow faster than native plants, and so can turn nice pieces of bush into weedy problems!

Land use change, particularly intensification, is a local driver contributing to the national trend of extinction of New Zealand’s great southern coastal plains ecosystems.

In the Waitaki District the biggest threats to wilderness values are:

  1. Modification or clearance of indigenous vegetation and fauna habitat through
    • Burning or clearing tussock grassland and native scrub
    • Planting exotic plantation tree species i.e radiata pine (Pinus radiata) or Douglas fir (Pseudostuga menziesii)
    • Pastoral intensification
    • Erosion
    • Eutrophication of freshwater habitats through nutrient enrichment
  2. Competition and predation by exotic weed and pest animal species,
    • i.e. Wilding pines, gorse and broom, didymo
    • i.e. feral cats, possums, goats, sheep, pigs, mustelids (stoats and weasels)
  3. Climate change
    • Sea level rise
    • Increased storm events
  4. Lack of awareness and information.
    • i.e. accidental clearance of native habitat

But it’s not all bad news! New Zealanders love nature, and there are plenty of local groups working hard to help preserve our natural heritage. Find out more about these groups at community nursery page.

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