Graduate Program
Biological Sciences
Degree Name
Master of Science (MS)
Semester of Degree Completion
Spring 2024
Thesis Director
Scott J. Meiners
Thesis Committee Member
Sanghoon Kang
Thesis Committee Member
Yordan S. Yordanov
Abstract
Mutualistic interactions with soil microbes are a key component of plant invasions. Mutualists such as ectomycorrhizal fungi and Rhizobia bacteria often limit invasive plant establishment and performance, but the role of nitrogen-fixing Frankia bacteria in invasions remains largely unexplored. In this study, I quantified the net effects of positive and negative plant-soil feedbacks, including Frankia nodulation, on invasive Elaeagnus umbellata (autumn olive; hereafter AO) seedling performance and traits at varying distances from focal shrubs using live soil and sterilized soil. The expectation was that seedling performance would decrease with further distance from shrubs as Frankia abundance decreased. Contrary to expectations, seedling biomass and specific leaf area increased with increasing distance from focal shrubs in live soil. The distance effects were driven by Frankia colonization as both nodule biomass and nodulation likelihood increased with distance from focal shrubs. Seedling performance and traits did not respond to distance in sterile soil, suggesting abiotic effects play a minimal role in inhibiting nodulation near focal shrubs. These data demonstrate that, while Frankia nodulation positively impacts AO performance, the abundance of Frankia does not limit AO establishment at local scales. The inhibition of nodule formation under shrub canopies is likely regulated by interference from antagonistic microbes or allelochemicals. Future studies should seek to elucidate the causes of nodulation inhibition and reduced nodule biomass under AO shrub canopies.
Recommended Citation
Leverette, Cody Anderson, "Are Elaeagnus umbellata Invasions Limited by Microbial Interactions?" (2024). Masters Theses. 5019.
https://thekeep.eiu.edu/theses/5019
