Do all legumes pose the same weed risk? Development of a method to evaluate the risk of introduced legumes to temperate Australia

Abstract

The importation of plants always carries with it the substantial risk of introducing new weed species. Currently, there is significant interest in the use of perennial legumes for the management of dryland salinity. In achieving this, it is highly likely that new legume species will have to be imported into Australia. However, a number of legumes have become serious weeds in temperate Australia with devastating effects on indigenous ecosystems. It would be advantageous therefore to be able to predict the level of impact a new legume species might have in natural systems. It would also be valuable to prioritize certain legume species that have recently naturalized for early control. Data gained from developing and distributing a questionnaire to people working with natural ecosystems suggest that herbaceous legume species, such as lucerne are having a low impact in natural ecosystems despite their long history of widespread cultivation. This is in contrast to the high level of impact that certain woody legumes, some brooms and gorse, have on natural ecosystems. In further studies it is hoped to identify key inherent biological attributes that are correlated to dominance of exotic legumes in natural ecosystems.