Clonal integration facilitates higher resistance to potentially toxic element stress in invasive alien plants than in natives

Background and aimsHeavy metal (especially for potentially toxic element) contamination in soil has frequently been associated with plant invasion. However, the mechanisms underpinning plant invasion under potentially toxic element contamination remain unclear. Here we studied how differences in clonal traits of invasive and native plants affect their response strategies to stresses of potentially toxic element contamination.MethodsWe manipulated clonal integration of two pairs (Alternanthera philoxeroides - A. sessilis, and Sphagneticola trilobata - S. calendulacea) of congeneric invasive and native plants by either severing stolons between ramet pair or not severing, and grew them in soils contaminated by three levels of Cd and three levels of Pb.ResultsOur results show that the combination of Cd and Pb contamination decreased plant growth of recipient ramets of Alternanthera species. Under Pb stress, invasive S. trilobata is Pb-hyperaccumulation and benefits more from clonal integration than native S. calendulacea. Similarly, under Cd stress, invasive A. philoxeroides shows higher Cd risk sharing and benefits more from clonal integration than native A. sessilis. In contrast, clonal integration decreased the performance of A. sessilis under high Cd stress.ConclusionThese results suggest that invasive species such as A. philoxeroides and S. trilobata are able to alleviate the toxic effects of Cd and Pb co-contamination via clonal integration, thus becoming more invasive in contaminated environments with potentially toxic elements.

Automated summary

This study found that clonal integration enhances the resistance of invasive plants to Cd and Pb, making them more invasive in environments contaminated with potentially toxic elements.