A review and development of a methodology
National Weeds Program. R.J. Adair & R.H.Groves
Environment Australia, April 1998
About the report
Environmental weeds threaten nearly all biological communities in Australia. Although weeds appear to degrade many natural ecosystems, quantitative measures of their impact on those systems are relatively rare. Information needed to establish priorities for the control of weeds in natural ecosystems include determination of the mechanisms of weed invasion, the ecological impact of the weeds and the threshold points for declines in biodiversity values as weed invasions proceed. Impact on alpha species-diversity has been the main focus of environmental weed studies to date, both in Australia and overseas. In nearly all cases, the impact of weeds is associated with a decline in native species richness or diversity. Beneficial impacts of weeds were determined only infrequently and mostly occurred on land already degraded, where weeds acted as 'nurse plants' for the regeneration of native overstorey components. Where ecosystemlevel functions are altered by weed invasions, habitat conditions or resource availability can be affected adversely for a broad range of species.