Status of coastal dune communities invaded by Chrysanthemoides monilifera

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 Moruva. 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 ofC. monilifera and Lomandra longifo]ia. 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 ofL. 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.

Identification of volatile compounds released by roots of an invasive plant, bitou bush (Chrysanthemoides monilifera spp. rotundata), and their inhibition of native seedling growth

“…In previous studies we have shown that the hydrophobic extracts (dichloromethane and acetone soluble) of bitou bush roots, leaves and soil, consistently inhibited the germination and seedling growth of a range of native plants (Ens unpublished data), including the native dominant of the system, acacia (Austin 1978;Weiss and Noble 1984b). This study was designed to identify the hydrophobic compounds that were likely to be responsible for the observed inhibition of seedling growth by the crude hydrophobic root and soil extracts.…”

Effects of herbivory and competition on an introduced plant in decline

“…High density of neighbours may reduce plant height (Harper 1977), and time of owering may be changed (The baud et al 1996). Studies have produced strong or highly suggestive evidence that the competitiveness of established invaders is correlated with their distribution (Weiss and Noble 1984). Competitive interactions between native and introduced species may thus aect both plant performance and population dynamics.…”

Seasonal gas exchange characteristics of Schinus terebinthifolius in a native and disturbed upland community in Everglades National Park, Florida

“…Studies have shown that exotics often differ from native species in ways that potentially contribute to their success within introduced habitats (e.g. Weiss and Noble, 1984;Busch and Smith, 1995;Dukes and Mooney, 1999;Yamashita et al, 2000;Horton et al, 2001). The objective of this study was to determine if gas exchange responses of Schinus were significantly different from native species in two communities, a native rock pineland community and a disturbed previously farmed area.…”