Mycorrhizas across successional gradients

Abstract

Ecological succession has been widely studied for more than a century, but the focus has mainly been on plant community dynamics over time. In the last 2 decades there has been a steady increase of research focused on mycorrhizal fungal succession, in part because of methodological advancements. In this chapter we first review mechanisms of mycorrhizal succession in terms of “habitat,” “plant,” and “fungal” drivers. Habitat drivers point to the importance of soil pH, P, N, and moisture during primary and secondary succession whereas P availability and soil pH are more important during long-term pedogenesis and at large spatial scales. Plant drivers such as size and age of root systems and host plant identity are often identified as important factors structuring and diversifying mycorrhizal fungal communities. Fungal drivers can also be important; mechanisms such as dispersal limitation of fungi can strongly influence the composition of ectomycorrhizal fungal communities and show considerable spatial and temporal dependencies. We conclude that no single driver rules them all; instead, the drivers interact and the relative importance of each driver depends on the spatial and temporal scales. We propose the “Interacting Drivers” hypothesis to highlight the importance of interactions between drivers. We also highlight promising topics and approaches for future research that should increase our understanding of the ecology of the mycorrhizal symbiosis but also better inform models of carbon sequestration and climate change.