Land
Theme commentary
Tony Gleeson, Synapse Research & Consulting
Alex Dalley, Ministry of Agriculture Fisheries and Forestry, Dili, East Timor
prepared for the 2006 Australian State of the Environment Committee, 2006
Introduced species
Introduced species are those that have arrived accidentally or been introduced to Australia intentionally since European settlement.
Some species, for instance rabbits, cane toads and many plant species have escaped or been abandoned and survive to establish wild populations with limited, if any net benefit. Once an introduced species establishes a self-sustaining population in the wild it is known as a naturalised species . Other introduced species, such as domesticated livestock, plant crop species, poultry, dogs and cats, are intentionally maintained because they provide economic or social benefits.
The pressures on the land resource from intentionally maintained species and responses to those pressures are dealt with indirectly in those parts of this commentary dealing with the impacts of agriculture.
Introduced species (wild or domesticated) can affect land condition, either because of the nature of their being or because they are not managed according to the requirements of the Australian environment. Especially in landscapes that have been anthropogenically altered to favour them (for example through urbanisation or the introduction of European-style agriculture), naturalised species have the potential to impact on land condition in several ways, with unpredictable consequences for ecosystems. They can outcompete resident species for food and habitat; they can prey on them at a rate that is unsustainable when compounded with other natural and anthropogenic pressures; or, in the case of grazing animals, they can contribute to land degradation.