Intraspecific variation in plant-soil feedback depends on plant
dominance while interspecific variation is unrelated to plant community
structure
Abstract
Plant-soil feedback (PSF) can both positively and negatively affect
plant populations. Diverse communities should dilute pathogens and
mitigate negative PSF, whereas plant dominance should have the opposite
effect. It is unclear, however, whether increased species and genetic
diversity can have additive effects on pathogen dilution. Using soils
from Medicago sativa production systems varying in dominance and
diversity, we inoculated multiple species and cultivars to assess
effects on PSF. We linked dominance and diversity to intra- and
interspecific variation in PSF via changes in microbiome composition.
Intraspecific PSF was more negative and variable as Medicago dominance
increased driven by multiple microbiome components. The mean and
variance in interspecific PSF responded to different microbiome
components but was unlinked to plant composition. Only oomycete
pathogens had similar effects within and among species. Independent
variation in PSF within and among species suggests additive benefits of
genetic and species diversity for pathogen dilution.