Global pine tree invasions are linked to invasive root symbionts

Abstract

Symbiotic soil microbes can facilitate plant invasions, yet it is unclear whether the invasive capacity of plants can be explained by the invasiveness of their microbial symbionts. We compiled a global database of one of the most widespread invasive non-native species on Earth ? pine trees and their major fungal symbionts, ectomycorrhizal fungi (EMF) ? and tested the hypothesis that the associations with invasive EMF increases the invasion success of pines. We found that successful pine species invasions are better explained by their association with invasive EMF than by aboveground plant traits that are typically used to explain plant invasiveness. Late-successional invasive EMF were most closely related to pine invasion success, implying that this subset of introduced EMF species might be key to sustain the invasion of their hosts. Our results suggest that the interaction with invasive microbial symbionts is an important predictor of plant invasion success.