Pest plant species

Indicator description

Pest plants are more commonly known as weeds. Pest plants can invade rural land (agricultural weeds) or natural habitats (environmental weeds). They are plants which, because of their characteristics and/or location, cause economic, ecological, physical or aesthetic problems, often with significant potential impacts on local and regional biodiversity.

The location and abundance of pest plant species are of interest to State of the Environment reporting because they indicate the pressure on the environment (both natural and agricultural) of the deliberate or accidental introduction of non-local species. Where introduced plants are found in streams, the location and abundance of the plants should be reported in relation to the length of the stream channel, because such plants can modify stream channels dramatically.

Most pest plants are non-native (introduced) species. However, some native species are also considered pests in certain circumstances e.g. Burgan Kunzea ericoides syn. Leptospermum phylicoides on grazing land or Cootamundra Wattle Acacia baileyana when translocated outside its original habitat.

Pest plants generally compete vigorously with native species for water, nutrients, light, habitat or pollinators: the result is often the elimination, at least locally, of native plants. This in turn affects animal biodiversity by removing or reducing food supplies, nesting sites and cover from predators.

Although most pest plants cannot invade undisturbed habitats (Pine Pinus radiata is an exception), they often prevent native species regenerating in disturbed areas, and thus require some form of weed control, usually with herbicides.