Soil heating resulting from prescribed burning in the southern US has potential immediate and long-term impacts. Where fire is being restored to long-unburned sites, the duration and depth of soil heating may be substantial, affecting seed banks, soil carbon cycling, and root and rhizosphere systems with often severe repercussions for overstory tree survival. Where fire has been used frequently, effects on soil quality are assumed benign, but this is not empirically proven. Current understanding of the relationships between fuels, prescribed burning, and soil heating is limited in southern pine ecosystems, even though the region burns a higher percentage of its forests than anywhere else in the US. To fill this knowledge gap, we characterized the relationships among fuels, fire, and soil heating in two widespread forest types of the South: pine flatwoods and pine sandhills. Second, to quantify ecological effects with clear management implications for ecosystem sustainability, we evaluated soil heating impacts on tree stress, vegetation, and soil respiration. Below-ground soil processes are integrated in soil respiration, which reflects the combined biological and physical consequences of soil heating and is a critical component of ecosystem carbon budgets. Overstory tree retention and diverse understory vegetation are principal goals for restoration of these ecosystems and are likely to be influenced by soil heating. We respond to research needs identified in previous studies by quantifying the consequences of soil heating across contrasting soils and fuel conditions. Our approach enables us to provide recommendations to managers and answer the question, 'Under what conditions should fire managers in the South be concerned about soil heating, and why?'