Host responses to AMF from plots differing in plant diversity

Increased plant species richness in a plant community leads to changes in the composition of the associated arbuscular-mycorrhizal fungal (AMF) community. We tested whether AMF from plots with increased plant diversity cause significant differences in the growth of Lespedeza capitata, Schizachyrium scoparium or Liatris aspera. Seedlings of each were transplanted into pasteurized soil inoculated with soil from their own monocultures, or from plots with one, seven, or 15 additional plant species. In addition, inocula from S. scoparium and L. capitata monocultures were tested for reciprocal growth effects. Inocula from plots containing the native tallgrass prairie species Lespedeza capitata showed increasing AMF species richness and spore density with increasing plant diversity; this was not true with plots containing Schizachyrium scoparium or Liatris aspera. All three species responded to AMF inoculation with increased growth and Cu concentrations, and lowered Mn concentrations compared to non-inoculated control plants. Increasing the plant diversity of the inoculum source-plots significantly affected plant weights of L. capitata, but not of the other two host plants. Both S. scoparium and L. capitata showed increases in growth with inoculum from S. scoparium monocultures compared to that from L. capitata monocultures. Spore density of inoculum source plots was associated with subsequent plant growth or nutrient content only in Lespedeza plots, which contained considerably fewer spores, plant cover, and root biomass in plots with lower plant diversity.