Taxonomic and multifunctional response of soil microbial communities to wildfire, prescribed fire, and partial harvesting in the Southern Appalachian Mountains, United States

Southern Appalachian forests have varied land-use history and are managed with different objectives, including maintenance of ecosystem services and harvesting timber. Concurrently, this region has experienced long-term wildfire suppression, causing shifts in dominant vegetation (i.e., mesophication) and is projected to have more frequent, severe drought and wildfire activity in the future. Regional wildland fire effects are not well understood in the context of the broader set of management activities, such as partial harvesting and prescribed burning, that influence soil microbial communities and the ecosystem processes they regulate. We use a taxonomic and multifunctional approach to compare soil across four watersheds with different management or disturbance histories: low-severity prescribed burning, high-severity wildfire, fire exclusion, or partial harvesting. Soil microbial community structure was influenced by historical disturbance effects, while ecosystem functions are constrained by resource availability following recent disturbance. Prescribed burns did not change microbial community composition relative to the fire excluded watershed; however, they did increase N availability and N acquisition enzyme activity. Microbial community structure of the post-wildfire and partially harvested watersheds was influenced by environmental filters related to disturbance, although microbial multifunctionality in the post-wildfire watershed was not significantly different from fire excluded and prescribed burned watersheds. The partially harvested watershed exhibited elevated NO 3 − and pH, increased C acquisition enzyme activity, and lowered C use efficiency relative to other watersheds. This study provides context to microbial influences on ecosystem dynamics following both anthropogenic and natural disturbances, helping managers understand the implications of management on forest soils and belowground processes.