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Aim: We examine how the climatic niches of North American tree and tall‐shrub species change after their introduction to Europe and how these shifts affect their potential geographical distributions in the new range. We ask whether patterns of niche shifts differ among species confined to different biomes in North America and whether the expansions of species' climatic niches and potential distribution ranges are related to their residence time in Europe and native range size. Location: North America and Europe. Taxon: Vascular plants (trees and shrubs). Methods: We used principal component analysis to quantify post‐introduction shifts in climatic niches of 59 species native to North America and alien to Europe. We modelled the expansions of their potential geographical ranges using Maxent. Differences in niche shifts and geographical expansion among species introduced from different biomes were tested using the Kruskal–Wallis test. Spearman correlation was used to relate niche and geographical expansions to residence time and native range size. Results: Alien trees and tall shrubs introduced from North America to Europe exhibited greater niche stability and unfilling than niche expansion, except for the species from Coastal Plain forests. The latter species showed the largest niche and geographical expansions. Species with a small native range in North America introduced to Europe long ago were more likely to expand to new climatic conditions and geographical areas. Main conclusions We show that (i) most North American tree and tall‐shrub species introduced to Europe still do not occupy all areas with suitable climatic conditions in their secondary distribution range, but species from Coastal Plain forests tend to expand into areas with climates not found in their native ranges; (ii) the potential of the studied species to spread in Europe depends on the climatic conditions in the biome of origin, the size of their native range and the time since the first introduction. [ABSTRACT FROM AUTHOR]

Aim The percentage of alien species found in a given habitat depends on the habitat vulnerability to invasion (invasibility) and the number of species introduced (propagule pressure). However, the global pool of alien species suited to a given habitat also varies. Here, we identify donor habitats of invasive alien plant species originating from Europe, examine the match between habitats they occupy in Europe and recipient areas and test whether donor habitats of invasive plants tend to be vulnerable or resistant to invasions. Location Europe (source area), North America and the World (recipient areas). Methods Native European vascular plants invasive in North America and other parts of the World were identified for 35 European natural habitats. Percentages of species invasive outside Europe, of the total number of native species occurring in each European habitat, were used to compare these habitats as donors for invasion. Habitat preferences of European species in their recipient areas were compared with those in Europe. Results European alluvial forests, alder carrs and coastal sand-dunes harbour the highest percentages of native species that are invasive outside Europe. Outside their native range, European species tend to invade habitats that are similar to their donor habitats in Europe, but species of alluvial and coastal habitats also frequently invade other habitats. European habitats that are important donors of invasive species globally experience the highest levels of invasion by alien species from other regions; this relationship was, however, not confirmed for invasions to North America if considered separately. Main conclusions Some European habitats are more important donors of invasive plants than others. Therefore, the level of invasion of different habitats is affected also by the differences in the number of invasive species provided by various donor habitats. At a global scale, more important donor habitats are also likely to be more invaded. [ABSTRACT FROM AUTHOR]

Vegetation of boreal coniferous forests has been extensively studied in many areas of northern Eurasia and North America, but similar forests in the high mountains of subtropical and tropical eastern Asia have been poorly documented so far. This paper, focusing on such forests, is the first phytosociological study at a national scale in Taiwan. The relevés from the National Vegetation Diversity Inventory and Mapping Project database were used to define vegetation types of the high-mountain coniferous forests and to characterize their distribution in Taiwan. Environmental variables such as aspect, elevation, soil rockiness and slope were related to species composition. Cluster analysis was used to classify vegetation plots and establish groups that were interpreted as nine associations belonging to two alliances. The alliance Juniperion squamatae represents woodlands and forests scattered in the subalpine belt, in which Juniperus squamata dominates the canopy and subalpine meadow species occur in the understorey. The Abieti kawakamii-Tsugion formosanae alliance includes forests dominated by Abies kawakamii and Tsuga chinensis var. formosana with shade-tolerant herb species in the upper montane belt. In addition to regional vegetation description, an identification key for the studied forests was developed based on the classification tree technique. [ABSTRACT FROM AUTHOR]

The factors that promote invasive behavior in introduced plant species occur across many scales of biological and ecological organization. Factors that act at relatively small scales, for example, the evolution of biological traits associated with invasiveness, scale up to shape species distributions among different climates and habitats, as well as other characteristics linked to invasion, such as attractiveness for cultivation (and by extension propagule pressure). To identify drivers of invasion it is therefore necessary to disentangle the contribution of multiple factors that are interdependent. To this end, we formulated a conceptual model describing the process of invasion of central European species into North America based on a sequence of "drivers." We then used confirmatory path analysis to test whether the conceptual model is supported by a statistical model inferred from a comprehensive database containing 466 species. The path analysis revealed that naturalization of central European plants in North America, in terms of the number of North American regions invaded, most strongly depends on residence time in the invaded range and the number of habitats occupied by species in their native range. In addition to the confirmatory path analysis, we identified the effects of various biological traits on several important drivers of the conceptualized invasion process. The data supported a model that included indirect effects of biological traits on invasion via their effect on the number of native range habitats occupied and cultivation in the native range. For example, persistent seed banks and longer flowering periods are positively correlated with number of native habitats, while a stress-tolerant life strategy is negatively correlated with native range cultivation. However, the importance of the biological traits is nearly an order of magnitude less than that of the larger scale drivers and highly dependent on the invasion stage (traits were associated only with native range drivers). This suggests that future research should explicitly link biological traits to the different stages of invasion, and that a failure to consider residence time or characteristics of the native range may seriously overestimate the role of biological traits, which, in turn, may result in spurious predictions of plant invasiveness.