Taxonomic resolution is a determinant of biodiversity effects in arbuscular mycorrhizal fungal communities

Arbuscular mycorrhizal fungi (AMF) are key regulators of ecosystem processes, yet how their biodiversity works in ecosystems remains poorly understood.
We documented the extent to which taxonomic resolution influenced the effect of biodiversity of AMF taxa on plant performance (growth, nutrient uptake and stress tolerance) in a meta-analysis of 902 articles.
We found that the effect of biodiversity of AMF taxa depended on taxonomic resolution. Plant performance was positively promoted by AMF family richness, while no effect was found for fungal species richness. In addition, negative effect was found between AMF phylogenetic diversity and plant growth. This pattern can be explained by functional conservatism within AMF families and functional differentiation among AMF families.
Synthesis. Conservation of AMF communities to maintain a full complement of ecosystem functions requires the presence of diverse families and not simply diverse species within a family. This finding may be of key importance for the function of ecosystems under various environmental perturbations to which AMF families may respond differently.