Impact assessment and analysis of sixty-six priority invasive weeds in south-east Queensland
George N. Batianoff and Don W. Butler, Queensland Herbarium, Environmental Protection Agency, Brisbane Botanic Gardens, Mt. Coot-tha Road, Toowong, Queensland 4066, Australia.
A reference panel of 13 professional scientists estimated the current level of impact and future impact of 66 priority environmental weeds in south-east Queensland. Impact scores did not significantly change the order of importance of most species relative to a previously published ranking based on invasiveness scores. The ten species ranked highest on impact, in descending order, were lantana (Lantana camara), cat's claw creeper (Macfadyena unguis-cati), Chinese celtis (Celtis sinensis), Madeira vine (Anredera cordifolia), camphor laurel (Cinnamomum camphora), green panic (Panicum maximum), broad-leaf pepper tree (Schinus terebinthifolius), asparagus ground fern (Asparagus aethiopicus), cabomba (Cabomba caroliniana) and ornamental asparagus (Asparagus africanus).
Future impact data indicate that the reference panel believe that most species will be more problematic in the future than they are at present. Priority arboreal weeds have been naturalized in the region for longer than the herbaceous weeds. Humans were responsible for the introduction of all 66 priority weeds in south-east Queensland, with 7% accidentally introduced and 93% deliberately introduced. The origins of these deliberately introduced plant species were ornamental (67%), agricultural (17%) and aquarium (9%). Humans (including use of roadside machinery), animals and water are the most important dispersers of these weeds. Roadsides are generally important habitats for exotic plants, including some priority environmental weeds (31% of these weeds are common on raodsides). However, the presence of environmental weed on roadsides has frequently been trivialized. Landscape managers need to be aware of this problem.
Plant Protection Quarterly (2003) 18 (1) 11-17.