Fungal-Mediated Above–Belowground Interactions: The Community Approach, Stability, Evolution, Mechanisms, and Applications

Our goal within this chapter is to review fungal-mediated above–belowground interactions in which belowground organisms influence aboveground organisms (or vice versa) primarily via a shared host plant, but to also highlight what we feel are the biggest areas for future research within this field: the community approach, stability, evolution, mechanisms, and application of these interactions. First, the community approach examines multiple simultaneously interacting species as communities, an approach that will greatly benefit from the future use of -omics techniques. Examining a greater diversity of interactions (via competition, facilitation, or predation) will likely reveal more varied outcomes that better describe patterns in nature than when individual interactions are considered. Second, we explore the stability of fungal-mediated above–belowground interactions. Given that systems can have multiple stable states influenced by multiple factors, we ask how frequently these interactions occur across stable states. Third, we present three areas in which we expect selection to influence fungal above–belowground interactions: simple (one-way) selective influences of organisms; evolutionary feedbacks and co-evolutionary arms races; and indirect versus direct selective influences. Fourth, we identify mechanisms driving the indirect interactions observed via host plants in fungal-mediated above–belowground interactions and factors influencing their context dependency. Finally, we explore potential applications of these interactions as novel biotechnologies to promote agricultural production, restore natural and degraded habitats, promote ecosystem services, and mitigate against the impacts of climate change.