Living together in a context of plant invasion: the example of the plant communities at the Iles Kerguelen

With invasions, functionally differing plant species meet. The traits of native and alien species should then be modified, affecting coexistence. We studied trait variation in four native and five alien plant species on the Iles Kerguelen along gradients of alien abundance. We measured traits related to competition and stress tolerance, and compared them along the gradients, their mean, variability, and range, at the species and the community levels, through univariate (analyses of variance) and multi-traits (hypervolume) approaches. Native and alien species occupied overlapping trait spaces, mostly because aliens are more variable than natives. Along the gradients, native and alien species showed similar mean strategies, with no variation in their trait range or variance. At the community level, a shift from convergence to divergence along the gradients was observed in most traits. Our results highlight that not only the response of aliens but also of native species should be studied under invasions.