Trophic Regulations of the Soil Microbiome

Predators of the soil microbiome regulate microbial structure and functions via both preferential and nonpreferential feeding, with implications on their structure (e.g., diversity) and functions (e.g., nutrient mineralization). The trophic cascade effects on the soil microbiome is often masked due to intraguild predation and omnivory in the soil. Less is known about how microbiome predators influence the competition between soil bacteria and soil fungi. Global climate change can alter the trophic ecology of the soil microbiome by making it fungus-dominated, depending on soil moisture and resource availability. We propose that the interaction among microbiome predators, plant inputs, and abiotic resources could interactively determine the structure of the soil microbiome. The soil microbiome regulates vital ecosystem functions ranging from primary production to soil carbon sequestration. Yet, we have only begun to understand the factors regulating the soil microbiome. While the importance of abiotic factors is increasingly recognized, the roles of trophic regulations in driving the structure and function of the soil microbiome remain less explored. Here, we review the current understanding of how and when microbial and top predators of the soil shape the community structure and function of the soil microbiome via both direct and indirect effects. We finally highlight that the structure and function of the soil microbiome depend on the interactive effects among predation, plant inputs, and abiotic variables present in the soil. The soil microbiome regulates vital ecosystem functions ranging from primary production to soil carbon sequestration. Yet, we have only begun to understand the factors regulating the soil microbiome. While the importance of abiotic factors is increasingly recognized, the roles of trophic regulations in driving the structure and function of the soil microbiome remain less explored. Here, we review the current understanding of how and when microbial and top predators of the soil shape the community structure and function of the soil microbiome via both direct and indirect effects. We finally highlight that the structure and function of the soil microbiome depend on the interactive effects among predation, plant inputs, and abiotic variables present in the soil. an indirect form of competition between or among prey species when they share a common predator, but with preferential feeding on one over the other prey. resources (living or nonliving) that form the base of food-web pyramids. the regulation of predators or consumers by their prey or resources. the soil not influenced by plant roots. effects that occur when changes in the abundance (or the biomass) of predators affect the density (or the biomass) of prey through direct predation, which, in turn, changes densities (or the biomass) of the resources of prey. those predators feeding on several prey species. the process of one predator feeding on another predator. predator species that can strongly affect the structure of prey communities without being higher in density. consumers that can feed on multiple trophic levels. the release of chemical compounds by plant roots into the rhizosphere soil. the soil immediately adjacent to plant roots. soil animals which feed on dead organic matter. the regulation of prey or resources by their predators or consumers. predators belonging to the top of the food chain, which, in this study, refers to those feeding on direct predators of the bacteria and fungi as well as saprophagous animals. effects that occur when changes in the abundance (or the biomass) of predators affect the trait (e.g., morphological, physiological, or behavioural) of prey through direct predation, which, in turn, changes densities (or the biomass) of the resources of prey. indirect species interactions originating with top predators and spreading downwards through food webs.