Effects of boneseed(Chrysanthemoides monilifera (L.) Norl. ssp. monilifera) on the composition of the vegetation and the soil seed bank of an open eucalypt woodland

P.B. ThomasA,C, H. PossinghamA,D and R. RoushB,E

A Department of Environmental Science and Management, University of Adelaide, Roseworthy Campus, South Australia 5371, Australia.

B Department of Applied and Molecular Ecology, University of Adelaide, Waite Campus, Glen Osmond, SA 5064, Australia.

Present addresses:
C Ecology Research Group, Hawkesbury Campus (K12), University of Western Sydney, Locked Bag 1797, South Penrith DC, New South Wales 1797, Australia.

D Ecology Centre, The University of Queensland, St Lucia, Queensland 4072, Australia.

E Integrated Pest Management, University of California, Davis, CA 95616-8621, USA.


The effects of the environmental weed boneseed(Chrysanthemoides monilifera (L.) Norl. ssp. monilifera) on the vegetation, and the soil seed bank, of an open woodland in the Mount Lofty Ranges were investigated. The vegetation and soil seed bank within infested and interspersed uninfested quadrats were assessed and compared. The most notable difference was a decrease in the abundance of two understorey dominants Gonocarpus tetragynus Labill. and Hibbertia exutiacies Wakef. within the infested quadrats. Also, the density of G. tetragynus and H. exutiacies decreased with increasing boneseed density. The understorey within the uninfested quadrats is dominated in terms of number, cover, and biomass by these two species, so their reduction represents a substantial community change. There were fewer G. tetragynus and H. exutiacies seeds, probably due to lower levels of productivity, in the infested quadrats. Seeds of these species had low levels of viability in the presence and absence of boneseed. There was a marginally significant (P = 0.057) reduction in G. tetragynus viable seed density in the infested quadrats. Boneseed seeds were present in uninfested areas, but at lower density. Diversity of both above-ground vegetation and the soil seedbank was reduced in infested areas. Changes in vegetation and viable seed densities may well comprise a long-term impact at this site, as regeneration might not restore the original species composition, and regeneration may take a long time to occur.


Plant Protection Quarterly (2005) 20 (2) 74-80.