Invasiveness in exotic plants: Immigration and naturalization in an ecological continuum

Abstract

A major goal of invasions ecology is to explain why some species are more successful as invaders than others, and ultimately to be able to predict traits predisposing a species to success in adventive environments. Unfortunately, to date few clear generalities exist and biologists are far from being able to predict future invasions. Recently several groups have shown how the lack of consensus on basic terminology has seriously limited progress in and application of invasions ecology, as well as its capacity to draw systematically on theory from ecological disciplines (Davis and Thompson 2000; Richardson et al, 2000a; Daehler 2001a; Davis and Thompson 2001, 2002; Rejmanek et al. 2002; Colautti and Maclsaac 2004). Within the literature, in regard to very similar ecological situations a particular species may be regarded as alien, exotic, invasive, colonizing, weedy, introduced, non-indigenous, imported or non-native. Moreover a weedy species may also be referred to as a naturalized-, transformer-, sleeper-, established-, casual-, persistent-, noxious-, native-, environmental-, or agricultural weed. Many of these terms connote only that a species is novel to a particular area. Others carry implications about actual or potential impact in novel habitats (see Davis and Thompson [2000] and Colautti and Maclsaac [2004] for a treatment of other terms). Here we are concerned primarily with species that are termed 'invasive' or 'invaders'. The scope of this notion alone covers much ground and in recent years debate over the criteria for regarding a species as invasive has received much attention (e.g., Davis and Thompson 2000; Richardson et al, 2000a; Davis and Thompson 2002; Rejmanek et al, 2002; Pysek et al, 2004) and the term continues to be used inconsistently. The debate on terminology is more than simple semantics because the use of inconsistent terms impairs understanding of the processes they are meant to describe (Colautti and Maclsaac 2004). © 2006 Springer. All Rights Reserved.