ABSTRACT
The National Research Council’s Committee on the Scientific Basis for Predicting the Invasive Potential of Nonindigenous Plants and Plant Pests in the United States pointed out the importance of understanding the biogeography of invasive plants in the first conclusion of its 2002 report:
Research on the biogeography of invasive plant species has focused on the distribution of nonnative species across geographic regions. In the United States, descriptions of the distribution of nonnative plants have involved the analysis of reports of occurrence within a county (Robinson et al. 1994) or among states (McKinney 2006), using electronic databases from herbarium specimens. In Europe, the research has involved the analysis of vegetation samples of many different environments across a city (Kowarik 1995; Dickson 2000; Grapow et al. 2001), country (Haruska 1989; Kuhn et al. 2004), or region (Kowarik 1990; Pyšek 1998). In the aforementioned research, rather than focusing on invasive species and examining differences in groups of invasive species segmented by growth forms, nonnative plants have been used as a stand-in for invasive plants, and growth form was not part of the analysis. Previous research on nonnative plants has not focused on comparing similar environments that have specific characteristics favorable to hosting invasive plants. Locales of special importance are the places where invasive plants have been introduced and the centers for the spread of the invasive species.
