Negative plant-soil feedback can contribute to plant species coexistence through the accumulation of species-specific soil communities that limit plant performance and create negative density dependence. However, the factors that influence the strength and direction of plant-soil feedback are largely unknown. Evolutionary history may play an important role. Closely related plant species may be more likely to share pathogens, which could dampen negative plant-soil feedback, decrease their probability of coexistence, and generate phylogenetic overdispersion in communities. Nonnative species can escape from co-evolved species-specific enemies present in their home range, creating weaker negative plant-soil feedback and increasing the probability that they become dominant. To determine the extent evolutionary history influences plant-soil feedback, its importance must be examined relative to other factors. Here we report results from a meta-analysis of over 500 pairwise plant-soil feedback comparisons where we tested the relative importance of twelve factors that may affect plant-soil feedback.
Results/Conclusions
We found that increasing phylogenetic distance between plant species strengthened negative plant-soil feedback, native plant species had more negative plant-soil feedback than non-native species, and that experiments that isolated mycorrhizal fungi produced weaker negative effects, suggesting soil pathogens play a major role in generating negative feedbacks. Our results demonstrate that plant-soil feedbacks, and particularly soil pathogens, are important for the maintenance of plant phylogenetic diversity and that escape from soil pathogens can be an important factor in the success of invasive plant species.