Abstract
There is growing evidence that loss of phylogenetic and functional diversity can alter ecosystem functioning, but related investigations mainly targeted aboveground communities. We assessed the performance of phylogenetic, functional, and species diversity metrics of plant communities as predictors of soil biota (abundance and diversity), six years from the onset of a grassland biodiversity experiment. We found that phylogenetic and functional diversity metrics outperform species and functional group richness as predictors of soil biota. The predictive power of the phylogenetic or functional metrics varied with the trophic affiliation of soil biota; macrosaprotrophs were better predicted by plant functional diversity, whereas macroherbivores and microbial biomass by plant phylogenetic diversity. The results indicate that phylogenetic and functional diversity metrics capture different sets of ecological constraints, and that we need to incorporate both approaches and consider the trophic position of the target organisms if we are to successfully predict impacts of plant species loss on belowground communities.