Date Approved

2024

Degree Type

Open Access Thesis

Degree Name

Master of Science (MS)

Department or School

Biology

Committee Member

Kristin Judd, Ph.D., M.S.

Committee Member

Steve Francoeur, Ph.D.

Committee Member

Emily Grman, Ph.D.

Abstract

Wetlands provide many ecosystem services, and invasive species and their management can alter these services. Plant responses to wetland management actions are typically monitored, but less is known about how soils respond. Phragmites australis, an invasive wetland plant, can alter soil conditions, potentially impacting soil microbial structure and function. We sampled soil communities in Great Lakes coastal wetlands in southeastern Michigan dominated by Phragmites and sites that had been previously invaded by Phragmites then treated with herbicide from 2011-2017, to understand how herbicide management alters soil fungal communities. We assessed microbial and fungal biomass, fungal community composition, greenhouse gas emissions, soil physiological profiles, and decomposition rates. Fungicide treatments of the substrate induced respiration assays had significantly lower microbial biomass carbon (p = 0.027), indicating that fungi were a detectable component of the soil microbial community. Further, sites undergoing herbicide management had significantly higher fungal class diversity (p = 0.042). Cluster analysis highlighted distinct differences in microbial communities at the ordinal taxonomic level between herbicide-managed and Phragmites-invaded sites. We found no significant differences in any of the functional variables between herbicide-managed and Phragmites-invaded sites. These findings suggest that changes in fungal community composition occur following herbicide management, but it is not clear to what extent managed soils recover to a pre-invaded condition or to what extent and over what time scales microbial functions are impacted.

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