Invasion biology: Toward a theory of impacts

The past decade produced an impressive collection of books and edited volumes on "invasion biology" (Groves and Burdon 1986, Mooney and Drake 1986, Joenje et al. 1987, Drake et al. 1989, Hengeveld 1989). These volumes brought together case histories of a large number of invasive exotic organisms from all taxonomic groups, and invaded communities from all corners of the globe. In addition to compiling case histories, this explosion of volumes produced a forum for the development of general observations and mostly verbal theory about the patterns and dynamics of invasions. Commonly noted was the lack of rigorous, mechanistic, experimental examples or tests of theory. In the years since the symposia that spawned these initial volumes, researchers have gone beyond natural history and have begun investigating particular invasions in great biological detail and with more rigorous methods. In addition, in part as a response to the general recognition of exotic species invasions as one of our most pressing environmental problems (Hedgpeth 1993, Office of Technology Assessment 1993, Ruesink et al. 1995, Parker and Reichard 1997), both researchers and agencies have begun compiling databases of introduced species.

It is now time to regroup and figure out what we've learned. Because of the recent surge of empirical work, we are in a much better position now than we were a decade and a half ago to move beyond arm-waving, and the time is right for a new synthesis. Our research will focus on successful invasions, and ask whether it is possible to predict which invasions will have a large impact on communities and ecosystems?