Climatic niche suitability, introduction history and their interactions with species characteristics drive establishment success of Asian woody species in European countries
The spread of invasive alien plants outside their native range constitutes a major threat to natural ecosystems, by causing a loss of biodiversity and a decrease in ecosystem functioning. Disentangling the roles of numerous intrinsic and extrinsic factors and their complex interactions is crucial to explicitly understand the mechanisms determining whether and how an alien plant species could pass through geographic, environmental and biotic barriers, and ultimately establish wild populations in new ranges. However, few studies have considered all these factors simultaneously. Especially, very few studies have explicitly tested the role of linear and non-linear interactions among numerous extrinsic and intrinsic factors in the establishment success and failure of alien plants in non-native ranges. In this study, we compiled a database of 449 Asian woody species that have all been introduced to Europe to test whether and to which degree their current establishment success in European countries depends on linear and non-linear effects of residence time, planting frequency, climatic niche suitability (assessed by niche-based species distribution modeling techniques implemented in biomod2) and species characteristics, and interactions between these variables.
We found that the establishment success of the species was significantly accounted for by the linear term of the residence time, planting frequency (i.e. propagule pressure) and climatic niche suitability, but species characteristics (i.e. maximum height, flowering and fruiting phenology, growth form, reproductive traits, and leaf retention, shape and size) had no significant main effects. However, the interactions between climatic niche suitability and some of the species characteristics (i.e. maximum height, flowering and fruiting phenology and leaf retention) significantly explained the establishment success. In other words, our results show that some of factors (e.g. species characteristics) are important in determining the establishment success but that their effects are context dependent. Therefore, we conclude that not only intrinsic and extrinsic factors but also complex interactions between them are crucial for understanding the process of plant invasion.