T. LOW

Chapel Hill, Brisbane, Queensland, Australia

Abstract

Introduced pasture plants are a serious threat to Australia's ecosystems. Five of Australia's worst environmental weeds are tropical pasture grasses and 2 are shrubs introduced for shade and fodder. The paper documents cases where exotic tropical grasses and legumes introduced for sowing pastures have invaded national parks and natural ecosystems. The effects of vigorous exotic grasses in altering the fire regime, thus adversely affecting biodiversity, are discussed. Exotic grasses used in ponded pastures eliminate habitat for native fish. Woody legumes and twining legumes also pose a grave threat.
Sown pastures frequently decline or fail because of run-down, marginal land, pest attack, or overgrazing. In these situations, new exotic pasture plants are wrongly promoted as the solution. Lower grazing pressures are likely to be more sustainable in the longer term. Because of the deleterious effects of exotic grasses, and twining and woody legumes, there is no justification for further introduction. Research should be directed towards developing native legumes and grasses, as a resource for the grazing industries.