Long-term Effects of Repeated Fire on the Belowground Ecosystem and Soil Nutrients: A Study of the Tall Timbers’ Stoddard Fire Plots in the American Southeast

Abstract

The historical use of fire in southeastern North America is well documented, yet the extended effects of fire on soil health and chemistry remain understudied. This study aims to evaluate the long-term effects of repeated fire on the O-horizon and surficial A and B horizons of mineral soil. In collaboration with Tall Timbers Research Station, we examined 65-years of fire effects (from prescribed burns on one, two, and three-year cycles) on soil organic carbon and nitrogen, pH, macroscopic charcoal, and plant pollen. Results indicate that within the fire treatment plots soil organic carbon, influenced by charcoal loading, is increasing alongside nitrogen levels. These repeated fire treatments also increase pH by leaving behind carbon and ash in the soil. Understanding these effects is vital, as fires oxidize organic matter releasing it to the atmosphere as CO2, nitrogen, and sulfur gases, it releases mineral nutrients in soluble forms, and contributes ash and charcoal to the forest floor and upper mineral soil.