Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Abstract Full Text

Weed risk assessment of the DEH Alert List and other non-native plant species.


Environmental weeds pose a significant threat to natural ecosystems in Australia. The risk posed to the environment by 51 non-native naturalised plant species, which include the Australian Government's Department of Environment and Heritage Alert List as well as an additional 23 species, were assessed in this project. Weed risk assessment processes investigating the invasiveness, impact and potential distribution of these species were developed and applied for this purpose. Weed risk for terrestrial and aquatic species was determined separately. Data for the weed risk assessment process was obtained from literature, Internet resources, herbaria (national and international) and questionnaires sent to experts in weed related fields. The potential distribution of these species in Australia was calculated using the climate modelling program CLIMEX and analysed using ArcGIS. The weed risk assessment process revealed that the 10 non-native terrestrial plant species that pose the greatest risk to natural ecosystems are, in order from most to less risk, Retama raetam, Acacia catechu, Nassella hyalina, Acacia karroo, Asystasia gangetica, Cytisus multiflorus, Nassella leucotricha, Barleria prionitis, Chromolaena odorata and Equisetum arvense. The top two aquatic species are Gymnocoronis spilanthoides and Lagarosiphon major. Several recommendations are made highlighting potential areas of action for the future.