Forest tree community ecology and plant-soil feedback: Theory and evidence

Mounting evidence suggests that reciprocal interactions between plants and the soil microbiota can be a primary force that generates key macroscopic patterns of plant communities (coexistence, dominance, and succession) in forest ecosystems. The aim of this article is to review empirical and theoretical perspectives of plant-soil feedback research in the context of forest community ecology. I first use a simple theoretical model to get insights into an array of the dynamics generated by plant-soil feedback: negative plant-soil feedback maintains plant species diversity and reduces plant growth, while positive plant-soil feedback drives plant growth of certain species and hence their dominance. I then describe how ecologists have unveiled the enormously complex plant-microbiota interaction (i.e., the soil conditioning experiment) and review the linkage of plant-soil feedback with three key plant community patterns: (i) dominance, (ii) spatial structure and (iii) succession. I highlight one belowground plant trait (mycorrhizal type) that can mediate these linkages: arbuscular mycorrhizal species tend to exhibit negative plant-soil feedback while ectomycorrhizal species tend to exhibit positive plant-soil feedback. Although mycorrhizal plant-soil feedback potentially explains the patterns of tree diversity from local to global scales, many questions remain. Future studies should expand plant-soil feedback theory to incorporate numerous other feedback mechanisms and test how mycorrhizal types mediate the net feedback effects that could propagate to shape large-scale forest structures and dynamics. Examples of red, conspicuous, bird-dispersed seeds produced by native Japanese tree species, a trait thought to be advantageous for escaping pathogens accumulated under parent trees and acquiring pathogen-free sites. image