Pathogen sharing between native and exotic plants correlates with exotic plant impact
When comparing the change in proportional plant biomass from what was originally planted to what was realized in plant communities, native plants were 40% lower in proportional biomass at the end of the experiment than at initial planting, whereas exotic plants were 60% larger, on average. Native plant performance (relative interaction intensity index, RII) decreased as the proportion of pathogens shared between native and exotic plants increased (χ2=5.72, p<0.02, Fig. 4A). In fact, the proportional native plant biomass from the beginning to the end of the experiment was consistently reduced in every community where exotic plants shared 30% or more of their pathogens with them (Fig. 4A). In contrast, the correlation between pathogen sharing and exotic plant success was not significant (Fig. 4B); rather, exotic plants made up a greater proportion of community biomass compared to that which they were planted in nearly every community where they grew.