Vulnerability of non-native invasive plants to novel pathogen attack: do plant traits matter?

Abstract

Exotic invasive plants are considered major threats to biodiversity globally; however, our understanding of the long-term dynamics of invasion remains limited. Over time, invasive plants can accumulate novel pathogens that may be capable of causing population declines because invaders have a greater chance of encountering such pathogens as they spread, and native pathogens can adapt to use invasive plants as a resource over time. However, reports typically focus on individual species and a framework capable of predicting pathogen vulnerability in plant invaders is not available. Pathogen resistance and tolerance may be related to plant traits, which we suggest can contribute to a framework for understanding and predicting the vulnerability of invasive plants to novel pathogens. We reviewed which traits of invasive plant species can aid in understanding the long-term dynamics of invasions due to associations between such traits and the vulnerability to novel-pathogen attack. We then extracted data from the literature to which we applied a multivariate model to associate plant traits with pathogen response to predict pathogen vulnerability of invasive plants. Finally, we provide directions for future research. There were 31 published tests of novel pathogen effects on invasive plant species in the introduced range. We found that together plant height, leaf nitrogen content, seed mass, specific leaf area, and leaf dry matter content can be useful in determining pathogen effects when included as part of a broader framework. We propose that more trait data for invasive plants are now needed to keep refining the predictive capacity of the proposed framework. Considering the emergence of trait-based approaches and comprehensive databases, advances in our understanding of invasive plant-pathogen interactions can lead to breakthroughs both at fundamental and management decision-making levels.