Can prescribed fire remain a viable management option in drought-prone environments without negatively impacting soil microbial communities?

Abstract:

Fire has long been a management tool used in grassland and savanna ecosystems to limit woody plant encroachment. However, predictions of increased frequency and duration of drought and fire pose a threat to key nutrient and carbon cycling processes in the soil. Soil microbes play a fundamental role in soil organic matter formation, degradation, and nutrient availability. As such, drought and fire can alter microbial biomass, composition, or diversity resulting in decreased nutrient cycling efficiency. Despite numerous studies assessing individual impacts of drought and fire on soil, few studies have analyzed the combined effect of drought and fire on soil microbial communities. To test how experimental drought, prescribed fire, and the interaction between drought and fire alter microbial community structure and function, we measured microbial biomass, extracellular enzyme activity, and 16S and ITS-based composition in response to prescribed fire and experimental drought in surface soils at the Texas A&M AgriLife research station in Sonora, Texas. We observed no effect of prescribed fire, drought, or the combination of drought and fire on microbial biomass or enzymatic activity. Additionally, we observed no change in microbial species richness or abundance in response to prescribed fire, drought, or the combination of drought and fire. Our results suggest that fire remains a viable management option in a semi-arid savanna ecosystem without concerns of negatively impacting soil microbes.