Arbuscular mycorrhizal fungi alleviate the negative effects of increases in phosphorus (P) resource diversity on plant community structure by improving P resource utilization

Nutrient resource utilization is essential for plant community composition and productivity. Previous studies found that an increase in resource diversity causes species losses and reduces plant diversity. Arbuscular mycorrhizal (AM) fungi can increase plant productivity and nutrient uptake, however, whether AM fungi can reduce the negative influence of nutrient resource diversity on plant composition is still not well understood. A microcosm experiment was conducted with four phosphorus (P) sources (at five levels of P resource diversity) and two AM fungal species, and the plant community composition, aboveground biomass, and P content were measured and calculated. Plant species diversity and richness decreased with increasing soil P resource diversity in the absence of AM fungi, while the decrease was less when AM fungi were present. The biomass and P content of the aboveground plants increased with increasing AM fungal diversity and soil P resource diversity. The results of a structural equation model suggest that AM fungi could reduce the negative effects of increasing P resource diversity on plant community composition by improving plant density and P uptake. Our results indicate that AM fungi can maintain higher plant species diversity and increase plant productivity by increasing P resource utilization efficiency.