Multisource grassland evidence for plant functional traits in predicting soil biota biodiversity and functions

• Plant attributes had a strong influence on soil fungal and nematode community. • Above-ground plant biomass was closely associated with soil bacterial diversity. • Plant phylogeny or composition was closely associated with soil fungal community. • Plant production or plant phylogeny was closely associated with soil nematode community. • Plant attributes had both direct and indirect effects on ecosystem functions. Theory and observation suggest that single-dimensional plant attributes and diversity may play a key role in explaining variation in soil biodiversity, but the empirical evidence in this area is still lacking considering multiple functional groups in soil biota. In this study, we explore the associations between plant taxonomic, phylogenetic, and functional diversity and soil biodiversity of multiple functional groups, as well as ecosystem functions in both monoculture and natural grasslands. We identified multidimensional plant attributes that could be categorized into three dimensions related to plant productivity, nutrient levels in leaves and roots, and phylogenetic relationships. We found that multidimensional plant attributes and soil properties commonly explained the biomass, richness and composition of soil biota across multitrophic levels, but this varied with the types of communities and their functional groups in both monoculture and natural grasslands. For example, plant functional traits or phylogeny explained more variation in soil fungi than in soil bacteria. Additionally, some links between multidimensional plant attributes and soil biota and soil functions were similar in both monoculture and natural grasslands, but there were weak effects of soil bacteria in the natural grassland and consistent strong effects of soil fungi in both monoculture and natural grasslands. This study provides experimental evidence supporting the effect of plant taxonomic, phylogenetic, and functional traits on shaping soil biodiversity and functions, which are crucial for understanding how plant-soil interactions may be impacted by ongoing global environmental changes.