Chrysanthemoides monilifera outcompetes native vegetation in coastal environments in Australia and New Zealand, and invasion can lead to a decline in both floral and faunal diversity, changing ecosystem composition. It grows in a range of habitats, and will resprout after fire, slashing or herbicide application. In addition, it can create a favourable environment for other invasive weeds, such as asparagus fern (Asparagus densiflorus), lantana (Lantana camara) and glory lily (Gloriosa superba) (CRC, 2003(a)(b)).
Location Specific Impacts:
Competition: Bitou bush (Chrysanthemoides monilifera ssp. rotundata) can outcompete and in some cases totally replace native flora in Australian coastal dune vegetation (CRC, 2003).
Ecosystem change: The structure and function of plant communities can be radically changed by Chrysanthemoides monilifera in Australia (ARMCANZ 2000). Lindsay and French (2004) showed that infestations of C. monilifera can alter ecosystem processes in coastal sand dunes. Dense infestations can alter the decomposition process by increasing the quality of the leaf litter layer and modifying microclimate. Increasing the rates of nutrient cycling may influence the rate of loss of nutrients from the ecosystem. Lindsay and French (2006) found that invertebrate total abundance was not reduced at sites of C. monilifera infestation, but the abundance of mites, thrips, spiders, ants, and centipedes was reduced at many sites. Thomas et al. (2005) found changes in vegetation and viable seed densities at sites with C. m. monilifera infestations.
Human nuisance: Dense infestations of Chrysanthemoides monilifera in Australia reduce the aesthetic appeal of natural areas, and access to walking tracks and visitor facilities can be adversely affected (ARMCANZ 2000).
Interaction with other invasive species: Bitou bush (Chrysanthemoides monilifera ssp. rotundata) stands can harbour pest animals such as foxes (Vulpes vulpes) and introduced birds in Australia (ARMCANZ 2000).
Other: Cultural effects of Chrysanthemoides monilifera in Australia can include localised impacts on Aboriginal sites, either by preventing access or beneficially providing stabilisation of sites subject to erosion (ARMCANZ 2000).
Physical disturbance: Dieback of older Chrysanthemoides monilifera infestations can lead to changes in dune shape and accelerated erosion in coastal Australia (ARMCANZ 2000).
Reduction in native biodiversity: Chrysanthemoides monilifera invasion in Australia leads to a decline in floral diversity, as well as changes in the diversity of birds, native mammals and ground-dwelling insects (ARMCANZ 2000).
New South Wales (Australia)
Threat to endangered species: Chrysanthemoides monilifera affects the following threatened species in New South Wales: Zieria prostata, sunshine wattle (Acacia terminalis ssp. terminalis), Austral toadflax (Thesium australe), white-flowered wax plant (Cynanchum elegans), Pimelea spicata
(see Australian Government Species and Threats database) and sand spurge (see Chamaesyce psammogeton in Threatened Species of NSW).
Threatened ecological communities include Eastern Suburbs Banksia Scrub (Sydney) and Kurnell Dune Forest (Sydney), and the significant areas SEPP 26 Littoral Rainforest and the World Heritage Listed Iluka Nature Reserve (ARMCANZ 2000).
Threat to endangered species: Chrysanthemoides monilifera affects the following species: blue devil (Eryngium ovinum), ribbed heathmyrtle (Thryptomene micrantha), cobra greenwood (Pterostylis grandiflora), the endangered small western spider orchid (see Caladenia colorata in EPBC Act List of Threatened Species), the rare Tasmanian endemic Eucalyptus risdonii, blue pincushion (Brunonia australis), the vulnerable conifer (see Callitris oblonga in IUCN Red List of Threatened Species), Australian anchor plant (Discaria pubescens), the threatened Epacris exerta, Australian mint bush (Prostanthera rotundifolia), Velleia paradoxa and the swamp violet (Viola caleyana). In addition, grassy Eucalyptus viminalis forests, E. risdonii woodlands, grassy E. globulus forest and shrubby E. ovata forests are impacted by C. monilifera (ARMCANZ 2000).
Reduction in native biodiversity: Chrysanthemoides monilifera affects the terrestrial orchid Pterostylis truncata, as well as manna gum (Eucalyptus viminalis ssp. pyoriana) vegetation association on Mornington Peninsula (ARMCANZ 2000).
Motuora Is. (New Zealand)
Competition: Rapid colonization of eroding cliffs and bare ground resulting in suppression of native species by competition.
Ecosystem change: Rapid colonization of eroding cliffs and bare ground resulting in suppression of native species by competition.
Motuihe Is. (New Zealand)
Competition: Boneseed (Chrysanthemoides monilifera monilifera) grows faster than, and shades out, slower growing native plants to become the dominant species (Laurence, J., pers. comm., 2008).
Motutapu Is. (New Zealand)
Reduction in native biodiversity: Boneseed (Chrysanthemoides monilifera monilifera) displaces native coastal species and prevents natural re-generation.
Rangitoto Is. (New Zealand)
Competition: Boneseed (Chrysanthemoides monilifera monilifera) prevents natural regeneration of coastal species.