Plant Mycorrhizal Feedback Patterns in the Context of Plant Life History and Phylogeny in the Prairie

Abstract

My research bridges the general themes of plant species coexistence, mutualistic interactions, and microbial feedbacks. These mechanisms have implications for our understanding of plant community dynamics, for land management, and for restoration projects. I study these mechanisms within the context of plant – AM fungal feedbacks. AM fungi associate with the roots of the plant, forming symbiotic exchange sites inside the root cells. AM fungal composition influences plant community dynamics, and plant‐AM fungal feedback provides a framework for understanding how the interactions between these two groups of organisms could drive patterns of plant biodiversity. My research extends the understanding of how plant‐AM fungal feedbacks are shaped and influenced by plant life history, and phylogenetic relatedness. My research also examines how the environmental disturbance of phosphorus fertilization influences these interactions and how that might be mediated by plant host characteristics. My research demonstrated AM fungal communities differentiate in response to training plant characteristics and phosphorus treatments. These changes resulted in positive feedback effects that were functionally different between early and late successional hosts. I saw consistent effects of the phylogenetic structure of host plants shaped AM fungal communities, with closely related plant species having similar AM fungal composition. Within early successional hosts, these changes in AM fungal communities fed back positively plant fitness of closely related species, contributing to phylogenetically under-dispersed communities. AM fungal community composition changed due to phosphorus enrichment, with less beneficial AM fungi decreasing while non-beneficial AM fungi increased, thereby predicting degradation of mutualistic quality of the AM fungal community. However, measured growth promotion of AM fungal communities with a legacy of phosphorus fertilization increased relative to AM fungal communities not exposed to fertilization. Overall, positive feedbacks between early and late successional plant species could result in alternative stable state. AM fungal dynamics could potentially constrain communities to dominance by early successional plant species, or they could accelerate successional turn over to dominance by late successional plant species. Additionally, the forces that maintain early successional dominated communities are expected to result in lower diversity.