Abstract

Plants interact consequentially with microbes spanning mutualism to pathogenicity, with broader effects on large-scale plant community structure. These plant communties, in turn, shape below and aboveground microbial communities through a variety of mechanisms. However, plant diversity-microbial diversity relationships remain broadly inconsistent across environments and among different plant and microbial assemblages. In my dissertation, I work to bridge some of these gaps in plant-microbial ecology in three experimental chapters assessing relationships between plant diversity and microbial diversity, including the influence of belowground-aboveground microbiome interactions, the influence of drought stress, and incorporating different spatial and experimental scales. First, I explore the microbial underpinnings of a plant-soil feedback between Monarda fistulosa and Plantago lanceolata, which only experienced a negative plant-soil feedback under both drought and pathogen stress. I sequenced the soil microbial communities associated with the treatment experiencing a feedback to better understand the microbial drivers. Second, I scale up from a two-species system to a many-species mesocosm experimental system, with the aim to understand how microbial communities are influenced by multiple co-occurring species and interactions with soil inoculation and drought stress. Finally, I assess the relationship between wild plant diversity and aboveground pathogen and herbivory damage, exploring how and whether dilution effects operate in Missouri glade restoration sites. Together, I find that plant species assemblages and environmental stress in the form of drought are important shapers of microbial community composition. Interpreting the ecological mechanisms underpinning microbial community responses to plant diversity differences woud benefit from higher taxonomic resolution of under-described microbial taxa, and higher-detail functional annotations. My research contributes to our understanding that multiple factors simultaneously and interactively shape patterns in plant diversity-microbial diversity relationships.

Committee Chair

Rachel Penczykowski

Committee Members

Christine Edwards; Jonathan Myers; Liz Mallott; Matthew Albrecht

Degree

Doctor of Philosophy (PhD)

Author's Department

Biology & Biomedical Sciences (Evolution, Ecology & Population Biology)

Author's School

Graduate School of Arts and Sciences

Document Type

Dissertation

Date of Award

8-19-2025

Language

English (en)

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