Patterns of loss of biodiversity associated with invasion by Chrysanthemoides monilifera subsp. monilifera (boneseed) across a large geographic region

Abstract

To investigate the impact of invasion by Chrysanthemoides monilifera ssp. monilifera (boneseed) on plant communities, sites that were invaded and uninvaded were surveyed across Tasmania, South Australia and Victoria, Australia. Above-ground cover abundance was estimated and samples of the seed bank from invaded and uninvaded sites in each state were collected and germinated in the glasshouse. We compared species richness and composition between invaded and uninvaded sites for both above-ground and belowground samples. Across this broad geographic area, C. monilifera invaded sites had 25% fewer species than uninvaded sites and twice as many exotic species. Most growth forms showed reduced richness in invaded sites. There were no differences in the composition of native species communities between invaded and uninvaded sites in most regions, except South Australia. The composition of the seed bank differed from the above-ground vegetation, but was similar within each state. Herbs and grasses were most abundant. The species composition of the seed bank was different in invaded sites only in Victoria, suggesting that invasion may negatively influence the capacity of the seed bank to restore vegetation in some areas. However, the underlying mechanisms for the observed patterns were not tested in this study. The capacity of all sites to regenerate effectively from the seed bank was limited and, in order to ensure the conservation of biodiversity into the future, monitoring of species richness at smaller scales, particularly those where management of C. monilifera has occurred, will be needed to ensure management can facilitate the establishment of missing species. This study suggests that C. monilifera impacts a range of functional groups and different species across its distribution and is therefore non-selective in how it influences changes in communities.

Invasive African boneseed and a native shrub support similar faunal assemblages in a heavily infested landscape

“…This gradient was similar between boneseed and native shrub sites, one possibility is that the prevalence of boneseed throughout the study area may act to reduce canopy complexity. Such trends have been quantified previously, with boneseed infestation reducing the density of dominant undershrub and reducing the diversity of above-ground vegetation and the soil seedbank (French & Watts, 2015;Thomas et al, 2005). These processes could negatively impact wildlife species.…”

“…was first introduced to Australia as an ornamental plant but has since spread and become a Weed of National Significance (Commonwealth of Australia, 2017). Boneseed impacts vegetation community composition and diversity and creates dense canopies limiting light infiltration (French & Watts, 2015;Thomas et al, 2005). It can support the increased establishment of other weeds (i.e., gorse Ulex europaeus) and decrease the standing biomass of native vegetation (French & Watts, 2015;McAlpine et al, 2009).…”

“…Boneseed impacts vegetation community composition and diversity and creates dense canopies limiting light infiltration (French & Watts, 2015;Thomas et al, 2005). It can support the increased establishment of other weeds (i.e., gorse Ulex europaeus) and decrease the standing biomass of native vegetation (French & Watts, 2015;McAlpine et al, 2009). Considerable effort is invested annually across Australia to control boneseed infestations, yet limited research has considered the potential ramifications of boneseed control on wildlife.…”

Giant invasive Heracleum persicum: Friend or foe of plant diversity?

“…In contrast to the synergistic effect or invasional meltdown hypothesis that emphasizes the positive role of exotic species in facilitating establishment and spread of other exotic species (Ricciardi, Hoopes, Marchetti, & Lockwood, ; Simberloff & Von Holle, ), our results indicate that H. persicum does not facilitate establishment of other exotic species. By reporting a high proportion of exotic invasive species co‐occurring with particularly dominant invasive species, several studies have supported the idea that exotic species facilitate each other's establishment, spread, and impact (e.g., French & Watts, ; Nielsen et al., ). However, our result does not support such an idea, as the other exotic species we found were overall few and scattered, and there was no difference in their occurrence between Heracleum invaded and noninvaded plots.…”

Ecological impact of Chromolaena odorata (L.) King and Robinson on native plant communities and soil seed bank in Ile‐Ife, Nigeria

“…This study not only demonstrated the negative impacts of C. odorata on vegetation parameters, but also brought into fore some important plant indicators that can persist with its invasion (Figure 1). Most notable among these species is A. africana , a native weed species which has a similar growth form as C. odorata because it is likely that competitive exclusion is weak among species of similar growth forms (French & Watts, 2015) irrespective of their status (native or alien). The extent of the negative impact of C. odorata was also reflected in the high correlation between the importance value index of the invasive weed species and the invaded site.…”