Multiple invasive plants show a lower trait plasticity in comparison to coexisting native plants under co-invasion...

Trait plasticity may be critical to the successful invasion of invasive plant species (IPS). Furthermore, multiple IPS can coexist in a given habitat. Nevertheless, it remains unclear which functional trait's plasticity contributes most to the competitive advantage of IPS under co-invasion scenarios. This study aims to evaluate the differences in trait plasticity, and to assess the contribution of the trait plasticity of multiple IPS to their competitive advantage under co-invasion scenarios mediated by three IPS, namely Erigeron canadensis L., E. sumatrensis Retz. and Solidago canadensis L., in comparison to native plants, in Jiangsu, China.

The study was conducted by cross-comparing plant communities under different invasion scenarios mediated by a different number of IPS, including plant communities invaded by one, two and three of the IPS listed above and plant communities without any invasion.

The three IPS displayed a significantly lower trait plasticity, particularly with regard to plant height, leaf size and green leaf area, in comparison to coexisting native plants, regardless of the invasion scenario. The competitive advantage of these three IPS was greatest when they invaded independently.

The competitive advantage of these three IPS was determined largely by the plasticity of green leaf area and leaf nitrogen content.