THE CHARACTERS OF SUCCESSFUL INVADERS

By: Mark H. Williamson & Alastair Fitter

Abstract
The characteristics of invading species were explored using the Ecological Flora Database, and by using comparisons available in other studies. Invasion success has been related to both abundance and distribution in the native range, which are themselves related. Abundance is probably the key variable. In the British flora invading species are characterized more by their distribution and morphology than by their life history and reproductive behaviour. The size of the plant and characters related to propagule pressure created by humans come out as important correlates of success. For biological characters, genetic studies and the phenomenon of boom-and-bust both suggest that the critical interaction between species and habitat is often subtle. Nevertheless, studies on pines and squirrels show that such important biological characters can be determined.

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