Abstract
Microbiomes are among the most diverse communities on Earth and play crucial roles in ecosystem functions. Despite growing recognition of these microbial hidden players, there are still many gaps in our knowledge of microbiomes and their interactions with hosts, including questions about their response and roles in ecological restoration and how intermicrobial interactions influence host performance. Here I investigate these gaps in knowledge using plant-microbiome interactions and a combination of microbiome sequencing, manipulative experiments, and synthetic communities. First, I investigate which biotic and abiotic factors structure soil microbial communities during restoration using constructed Everglades tree islands. I found that restoration decisions influencing biotic and abiotic components of the landscape can have important consequences for soil microbial community diversity, composition and function even 15 years after restoration. Next, I investigate the effects of microbial diversity and intermicrobial interactions on plant performance in an experiment inoculating plants with synthetic communities of fungal endophytes. Non-additive effects on plant performance were pervasive, interactions among ‘commensal’ fungi were responsible for this non-additivity, and fungal diversity affected the magnitude of non-additivity. This chapter demonstrates the importance of considering intermicrobial interactions when examining the effect of microbial communities on their plant host. Last, I investigate how environmental stressors impact plant-microbe interactions by determining how microbial communities interact with changes in hydrological conditions to have cascading effects on plant performance. I find that tree island microbiomes from the Everglades can mitigate the effects of flooded conditions for their plant host. Overall, this research explores how biotic and abiotic conditions have effects on microbiomes and their interactions with plants.