The invader shrub Chrysanthemoides monilifera (boneseed) negatively impacts native plant communities in a Mediterranean zone in Central Chile

Biological invasions have severe social, economic and ecological repercussions. Central Chile is a biodiversity hot spot but also a highly disturbed area containing many invasive plant species such as Chrysanthemoides monilifera (L.) Norl. This shrub is present close to the coast and is considered an aggressive invasive species with allelopathic effects in other countries. Despite being ubiquitous, its invasive potential and ecological impact has not yet been evaluated in Chile. Here, we aim to determine the effect of the invasive C. monilifera on local plant communities and test for possible allelopathic effects on the germination of native and other invasive species. To do this, we analyzed plant diversity in patches with and without the invader in two sites in Valparaíso, Chile. Additionally, we conducted an experiment testing the effect of different concentrations (0, 25, 50 and 100%) of the aqueous extract of the leaves on the germination of both a native and an invasive shrub. We found that C. monilifera negatively impacts local plant diversity, especially endemic species. Also, its leaf extract inhibited the germination of the native shrub, especially at higher concentrations (50 and 100%), but do not inhibit the germination of the invasive shrub. This will likely result in a rapid change in the plant community, with negative impacts on the native species and an increase in invasive and introduced species, further degrading this already altered ecosystem. Developing strategies for the control of C. monilifera are urgent to limit its spread and negative ecological impact in Chile.