Doctoral Dissertations

Orcid ID

Date of Award


Degree Type


Degree Name

Doctor of Philosophy


Civil Engineering

Major Professor

Terry C. Hazen

Committee Members

Qiang He, Jon M. Hathaway, Sally P. Horn


Prescribed fires in Southern Appalachian forests are vital in ecosystem management and wildfire risk mitigation. However, understanding the intricate dynamics between these fires, soil microbial communities, and overall ecosystem health remains challenging. This dissertation addresses this knowledge gap by exploring selected aspects of this complex relationship across three interconnected chapters.

The first chapter investigates the immediate effects of prescribed fires on soil microbial communities. It reveals subtle shifts in porewater chemistry and significant increases in microbial species richness. These findings offer valuable insights into the interplay between soil properties and microbial responses during the early stages following a prescribed fire.

The second chapter delves into the lasting impacts of controlled burns on soil carbon and nitrogen isotopic compositions. It showcases diverse carbon and nitrogen concentrations in soil cores, emphasizing increased carbon content for specific treatments. Stable isotope analyses showed shifts in δ13C and δ15N values, with measurable differences in postfire δ15N for various fuel types. The loss of isotopically light carbon during the fire event is attributed to burning soil organic carbon.

The third chapter explores the influence of fire frequency on soil microbial communities and nutrient dynamics, emphasizing the substantial impacts of burn frequency on microbial biomass carbon (MBC) and the importance of recovery periods between burns. A detailed examination of bioavailable nutrient concentrations and pH uncovers the intricate relationship between fire frequency and soil properties. This research examines the role of different fire-frequency regimes in shaping these connections and their importance in informed land management for preserving Southern Appalachian mixed forests.

In conclusion, this dissertation provides significant insights into the relationships between prescribed fires, soil microbial communities, and nutrient cycling in Southern Appalachian mixed forests. Land managers can make more informed decisions about when and where to implement fire as a management tool in these forests by understanding the relationships between the soil microbiome and nutrient cycling. This research highlights the importance of considering fuel types and fire frequency to promote healthy ecosystem functioning and maintain biodiversity. Overall, the findings contribute valuable knowledge to the field of fire ecology, aiding in the conservation of these crucial ecosystems.

Files over 3MB may be slow to open. For best results, right-click and select "save as..."