NATIVE AND ALIEN INVASIVE PLANTS - MORE OF THE SAME

We compare the ecological and habitat characteristics of alien and nat ive vascular plants which have recently expanded in range in England, Scotland, the Republic of Ireland and the Netherlands. In the great ma jority of respects, expanding aliens and natives are functionally indi stinguishable. However, there are a few consistent differences: aliens are more likely than natives to be clonal, polycarpic perennials with erect, leafy stems, and to have transient seed banks. We discuss thes e trends in the context of the difficulties faced by aliens in invadin g mostly closed plant communities in relatively cool, damp climates. O ur results are consistent with some predictions of the attributes of ' ideal' invaders, but contradict others. We argue that the ecological a ttributes of successful alien invaders are strongly habitat-dependent.