The impact of bridal creeper (Asparagus asparagoides) on native ground-cover plant diversity and habitat structure

Abstract

This study investigated the impacts of one of Australia's most serious environmental weeds, bridal creeper (Asparagus asparagoides), on a diverse native ground-cover plant community in Eucalyptus woodland. Bridal creeper is a creeping geophyte with an extensive root system of tuber-bearing rhizomes that has the potential to cover large areas of ground with dense foliage. Despite being a well-recognized 'Weed of National Significance' and its obvious overall impact in invaded areas, there are very few quantitative studies of the effects of this weed on native plant diversity and the habitat it invades. In a comparison of adjacent invaded and non-invaded habitat the impact of bridal creeper was found to be detrimental. There was a significant decrease in total species richness and frequency of native ground-cover plants in invaded areas, however the total species richness and frequency of exotic species were not significantly reduced. There was a significant negative correlation between weed intensity (per cent cover) and the number of native and exotic species. A reduction of open, mossy patches and an increase in the level of Eucalyptus leaf litter in invaded habitat also suggests that bridal creeper has the potential to modify habitat structure. The possible consequences of the replacement of a species-rich and open ground-cover habitat into a closed homogenous one with increased leaf litter are discussed.