Plant community associations of two invasive thistles

Site INDRL, an abandoned industrial site, covered with a high density of Carduus thistles, common teasel and other invasive plants (photo by E. Rauschert).
Site INDRL, an abandoned industrial site, covered with a high density of Carduus thistles, common teasel and other invasive plants (photo by E. Rauschert).

To combat the growing problems associated with biological invasions, many researchers have focused on identifying which communities are most vulnerable to invasion by exotic species. However, once established, invasive species can significantly change the composition of the communities they invade. The first step to disentangling the direction of causality is to discern whether a relationship with other vegetation exists at all. In a new study published in AoB PLANTS, Rauschert et al. assessed the field-scale plant community associations of Carduus nutans and C. acanthoides, two similar, economically important invasive thistles. Several plant species were associated with the presence of Carduus thistles while others, including an important pasture species, were associated with Carduus-free areas. Thus, even within fields, areas invaded by Carduus thistles have different vegetation than uninvaded areas, either because some plants can resist invasion or because invasion changes the local plant community. The authors’ results will be used to target future research about the role of vegetation structure in resisting and responding to invasion.