| Abstract: | It has often been assumed that the introduced species Chrysanthemoides monilifera is displacing native species in invaded coastal communities in Australia but no direct evidence has been presented that this displacement is occurring and, if so, to what extent. At an invaded site near Moruya, New South Wales, we found strong negative correlations between the presence (measured as cover, frequency or volume of shrub) of C. monilifera and Acacia longifolia, the hitherto dominant native species, and of C. monilifera and Lomandra longifolia. The negative correlations are partly accounted for by differences in the amounts of each species on different zones on the dune, but the negative correlations remain even within these zones. Also a comparison with uninvaded sites indicates that C. monilifera is displacing A. longifolia from the fore-dune and mid-dune but is having less effect in the swale. In addition, there is a trend towards reduced seed production of A. longifolia when growing in proximity to C. monilifera. There is no significant difference in the presence of L. longifolia in the uninvaded and invaded sites. In invaded sites, significantly fewer C. monilifera seedlings occur in the presence of L. longifolia. Thus it appears that the observed negative associations arise from different causes. Chrysanthemoides monilifera is displacing the structurally similar, and previously dominant A. longifolia, while the tussock-forming L. longifolia is locally hindering the invasion. |
