What are exotic perennial grasses?
Exotic perennial grasses have a life span of more than one growing season. They have been accidently and deliberately introduced into Australia since colonisation, where they displace native vegetation, impact native animals, and impact agriculture.
Exotic perennial grasses are legislated as a key threatening process under the NSW Biodiversity Conservation Act 2016, posing a significant risk to the conservation and ongoing management of threatened biodiversity.
Why are exotic perennial grasses a threat?
Exotic perennial grasses may exhibit vigorous growth, copious seed production and effective seed dispersal mechanisms, enabling them to compete strongly with native vegetation. Exotic perennial grasses can change the structure, composition, and fuel loads of plant communities. The changed structure and fire regime of the habitat are likely to negatively impact both native animals and insects.
Exotic perennial grasses compete strongly with, and even displace, native vegetation, including native grasses. Exotic perennial grasses pose significant risks to many native species and ecosystems. Native grasslands and open woodland communities, including threatened ecological communities such as Box Gum Grassy Woodland, are particularly susceptible to invasion.
Aren't some exotic perennial grasses important?
Some exotic perennial grasses are intentionally introduced for use in pasture and garden plantings. These species are termed 'trade-off', or contentious species. They provide economic benefit but are invasive in native communities, causing environmental losses. High propagule pressure and differences in the management of these grass species increases the likelihood of spread into native areas.