Analysis of AM Fungal Community Structure in the Roots of Different Host Plants
We established monocultures of 20 grass species under standardized field conditions, quantified their phylogenetic relationships and key functional traits, and characterized root-associated AM fungal communities via high-throughput sequencing. Our results demonstrate significant host-specific filtering of AM fungal assemblages, primarily driven by species turnover (ß-diversity). Phylogenetic distance between hosts emerged as the principal direct driver of fungal community composition. In contrast, plant height was the strongest predictor of a-diversity, encompassing both species richness and phylogenetic dispersion (Net Relatedness Index). Structural equation modeling confirmed that the influence of phylogeny on a-diversity was indirectly mediated by plant height, whereas its effect on ß-diversity was direct. Our findings reveal a decoupling of assembly mechanisms: plant phylogenetic relatedness directly shapes ß-diversity, while plant height, itself phylogenetically constrained, primarily governs a-diversity.