Short-term prescribed fire-induced changes in soil microbial communities and nutrients in native rangelands of Florida

Prescribed burning is widely used land management strategy to reduce the risks of wildfire and to achieve a wide range of ecological, economic, and societal benefits. However, it can also affect carbon (C), nitrogen (N), and phosphorus (P) cycling with potential subsequent effects on soil microbial communities. This study examined the short-term effects of prescribed burning on soil chemical properties, potential enzyme activities, and bacterial and fungal community composition in native rangelands of Florida. Fire-induced responses were assessed immediately (2 days) and 2 to 3 months after a prescribed fire event. Soil pH, total C, and extractable NH4+ and P concentration declined after fire. Total N concentration increased 2 days after fire but returned to initial level 2 to 3 months after fire. Prescribed fire elicited no observable effects on soil total P and extractable Ca, K, Mg, Mn, Fe, and Al concentration. Reductions in potential beta glucosidase and N-acetyl glucosaminidase activity were observed 2 days after fire but returned at pre-fire levels after 2–3 months. Bacterial and fungal diversity and community composition at the phylum level showed no short-term changes. At the Order level, bacterial Desulfurellales increased while fungal Eurotiales and Pleosporales decreased 2 days after fire. Prescribed burning had minimal effect on soil microbial community composition in the short-term, probably due to limited effects of fire on soil heating and rapid post-fire vegetative recovery. Although the impacts of prescribed fire on soil properties have been widely acknowledged, this study is the first to document short-term fire-induced soil microbial responses in subtropical native rangelands of Florida. This work contributes to a wealth of evidence indicating limited impacts of prescribed fire on soil microbial community composition.