Date of Award

Spring 5-2023

Degree Type

Thesis

Degree Name

Master of Science (MS)

Committee Chair

Joel Graff

First Advisor

Robert Pal

Second Advisor

Katie Hailer

Abstract

Soil microorganisms provide ecosystem functions and services critical for life, can have lasting effects on aboveground plant communities, and can serve as indicators of soil quality. However, biotic indicators are underrepresented in soil health assessments. Incorporating microbial soil evaluations in ecological restoration studies are important in order to obtain a more comprehensive understanding about their role in healthy soil development. In this study, we used three bioindicators to assess the post-restoration soil microbiome recovery of the Upper Clark Fork River: extracellular soil enzyme activity, microbial biomass, and microbiome community and diversity. We found that microbiome recovery rate varied at different phases of the restoration site, with one section still exhibiting low microbial biomass and enzyme activity after eight years of recovery. Prokaryotic community compositions of the different sites were compared. Prokaryotic communities from the study site separated into two groups based on Bray-Curtis measurements. These groups were unique compared to communities from the control site. We further tried to assess soil function through a soil inoculation experiment. Sandbar willow cuttings were grown in sterile soil inoculated with live or sterilized samples from different phases of the restoration site. Inoculation treatment (live or sterilized) and collection site did not influence willow growth, however, willow cutting mass had a significant effect. Extracellular soil enzyme activity was higher in soils inoculated with live inoculant than those inoculated with sterile inoculant. Inoculation with live soil from all collection sites increased enzyme activity over soil inoculated with unsterilized backfill soil. Inclusion of biotic indicators in soil health assessments may elucidate environmental factors and management actions that contribute to variance in microbiome recovery rates observed, leading to more effective restoration practices, and increasing the likelihood of self-sustaining, resilient ecosystems.

Comments

A thesis submitted in partial fulfillment of the requirements for the degree of

Ecological Restoration, M.S.

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