Contrasting effects of pathogen- and light-mediated processes on the diversity- invasibility relationship

The diversity-invasibility relationship remains highly debated, and many biotic and abiotic factors may serve as important drivers. To evaluate the effects of pathogen- and light-mediated processes on invasibility of forests, we integrated seedling dynamics with measurements of foliar pathogenic fungi and canopy cover in a large-scale forest biodiversity experiment in China. We found that survival rates of closely-related seedlings were high in species-rich stands due to a low abundance of pathogenic fungi. In contrast, the growth of distantly-related seedlings was inhibited due to the low light availability in species-rich stands. Our results demonstrate that foliar fungal pathogens and light availability modulate diversity-invasibility relationships, and that these effects depend on the phylogenetic relatedness of invader and host plant community.