PS 8-102 - Plant diversity and soil microbiota as drivers of productivity in the tallgrass prairie

Abstract: Grasslands are the most widespread, as well as one of the most threatened, terrestrial ecosystems. Grasslands provide a suite of key ecosystem goods and services, many of which are threatened as a result to loss of grassland cover. The loss of grasslands across the globe, coupled with their importance in providing ecosystem goods and services, has fueled a growing interest in the role of grassland biodiversity in maintaining these processes. The overarching goal of this research was to assess the biodiversity-productivity relationship of tallgrass prairie plant communities, and how this relationship is influenced, and if so, to what degree, by the soil microbiome. Additionally, we assessed the relative influence of plant species richness, diversity, and phylogenetic dispersion on soil aggregate stability and carbon storage. Using plots established in 2018 at the University of Kansas Field Research Station, we tested the effects of plant community structure and microbial community assemblages on carbon storage and other soil measurements that are important for soil health, such as soil aggregate stability and microbial abundances. In 2018, plots were planted to one of five species richness treatments (1, 2, 3, 6, or 18), with species assemblages represented by either phylogenetic under- (single taxonomic family) or overdispersion (2 or 3 families). Taxonomic families used in the experiment were Asteraceae, Poaceae, and Fabaceae, representing the three most common families in tallgrass prairie plant communities. Additionally, plots were inoculated with one of three soil inocula: 1) lab-cultured AM fungal propagules, 2) whole prairie soil containing the full suite of soil microbiota, and 3) sterile prairie soil. For the past five years (2018-2022), plots were visited monthly across the growing season (April-October), during which plant cover was assessed visually. Our results indicates that plant phylogenetic dispersion tended to increase productivity, which is supports previous research. Complementarity and selection within the planted communities were largely driven by interactions between various combinations of year, inoculum type, species richness, and phylogenetic dispersion. Net biodiversity effects were overwhelmingly driven by the interaction between phylogenetic dispersion and year. Additionally, AM fungal abundances and soil aggregate stability were significantly greater in plots with greater plant species richness and phylogenetic diversity. These results suggest that plant community dynamics, such as richness and phylogenetic diversity, soil microbial communities, and time interact to facilitate observed biodiversity-productivity relationships, and that these relationship also facilitate key soil-related ecosystem services