Linking biotic homogenization to habitat type, invasiveness and growth form of naturalized alien plants in North America
Aim Biotic homogenization is a growing phenomenon and has recently attracted much attention. Here, we analyse a large dataset of native and alien plants in North America to examine whether biotic homogenization is related to several ecological and biological attributes. Location North America (north of Mexico). Methods We assembled species lists of native and alien vascular plants for each of the 64 state- and province-level geographical units in North America. Each alien species was characterized with respect to habitat (wetland versus upland), invasiveness (invasive versus non-invasive), life cycle (annual/biennial versus perennial) and habit (herbaceous versus woody). We calculated a Jaccard similarity index separately for native, for alien, and for native and alien species. We used the average of Jaccard dissimilarity index (1 ) Jaccard index) of all paired localities as a measure of the mean beta diversity of alien species for each set of localities examined in an analysis. We used a homogenization index to quantify the effect of homogenization or differentiation.