Electronic Theses and Dissertations

Date of Award


Document Type


Degree Name

M.S. in Biological Science



First Advisor

Colin R. Jackson

Second Advisor

Jason D. Hoeksema

Third Advisor

Stephen Brewer

Relational Format



Soil microorganisms play vital roles in biogeochemical cycles and are necessary for maintaining soil health. An invasive plant that alters the structure and function of the soil microbial assemblage could gain an advantage over native plants, enhancing its ability to invade new habitats, alter ecosystem function, and hinder efforts to reestablish native populations. Assays of enzyme activity and next generation sequencing of bacterial 16S rRNA genes were used to assess the soil microbial function and community structure associated with the invasive grass, Microstegium vimineum and two co-occurring native grasses (Dichanthelium boscii and Chasmanthium laxum). Significantly lower enzyme activity was found for soil associated with M. vimineum compared to the other plant species, and that each plant had a distinct bacterial community associated with it. Differences in bacterial community structure were more apparent on the root surface or in the rhizosphere, and may not extend into the surrounding bulk soil and were seen throughout the sampling season. Site chemistry differences affected enzyme activity but not bacterial community composition, suggesting that bacterial community structure is influence more by plant species than soil chemistry. Microstegium vimineum also significantly increased soil pH. Long-term invasion of M. vimineum will cause local changes in nutrient cycling, changes in soil pH and alter local bacterial community composition.


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