A general approach for quantifying microbial effects on plant competition

Purpose  A growing perspective in plant ecology highlights the ways that microbial interactions can promote or hinder plant coexistence. Towards this aim, recently-proposed approaches provide ways to empirically quantify how microbes affect the outcome of competition between plants. One such approach experimentally measures competition coefficients by comparing biomass performance of plants growing individually or with competitors, then quantifies microbial effects by comparing with a sterilization treatment. Nonetheless, the complexity of plant-microbe interactions presents general challenges when linking observations of microbial effects to underlying models.
Results  We show how the implementation of a density gradient design can help quantify potential nonlinearities and facilitative interactions in plant-soil microbe interactions, which are properties once thought to hinder the quantification of the microbial impact of plant competitive outcome. We provide guidelines for setting up...