Can we foresee future maple invasions? A comparative study of performance-related traits and invasiveness of eight Acer species

Determining traits correlated with invasiveness in order to identify potentially invasive species remains a priority in the field of invasion ecology. In trees, relative growth rate (RGR), specific leaf area (SLA), or plant height under optimal growing conditions have been identified as performance traits allowing pioneer exotic species to outcompete native species. However, few studies investigated the link between these traits and invasiveness on a continuous scale. Here, we compare the RGR, SLA, height, shoot–root ratio, and number of leaves of seedlings of eight maple species (Acer spp.) with their invasiveness at the global level. Seedlings were grown in non-limiting conditions indoor in Gembloux, Belgium and harvested after 2, 4, or 8 weeks. Global invasiveness was quantified using a combination of the number of regions and countries invaded in the GBIF database, the number of citations in the Global Compendium of Weeds (GCW), and the risk score estimated in the GCW. RGR, SLA, height, and number of leaves after 8 weeks were positively correlated with invasiveness. We conclude that invasive maple species could benefit from an acquisitive strategy and that high growth and light capture also favor invasiveness of shade-tolerant species. Finally, we recommend a close monitoring of Acer rufinerve in Western Europe due to its high RGR and SLA, comparable to other highly invasive maple species.