Soil Factors Influencing Wildfire Behavior and Severity: A Review

This review synthesizes current knowledge on how soil-related factors influence wildfire behavior and burn severity. Key soil factors include soil moisture status, texture and structure, organic matter content (e.g., peat and duff layers), microbial activity, and properties like compaction, erosion, and water repellency. Soil moisture emerges as a critical control on fuel flammability and fire spread potential, with drought-prone soils and low soil water content strongly correlating with larger, more intense fires in many ecosystems. Soil texture and structure mediate infiltration and water retention, thereby affecting vegetation moisture and fuel continuity. Soils rich in organic matter (such as peatlands) can sustain smoldering combustion, and lead to extreme fire severity and carbon emissions when sufficiently dry. Repeated fires and intense burns can degrade soil structure, reduce nutrient availability, and induce hydrophobic (water-repellent) soil conditions that promote runoff and erosion, further influencing future fire regimes. We highlight global examples—from boreal peat fires and tropical rainforest burn scars to temperate forest and savanna soils—illustrating the multifaceted roles of soils in fire dynamics. Improving wildfire prediction and management under climate change requires integrating soil parameters (e.g., soil moisture monitoring, organic layer depth, post-fire soil assessments) into fire danger indices and ecosystem models. This review provides a comprehensive, up-to-date examination of soil–fire interactions and discusses implications for fire ecology, carbon cycling, and land management in fire-prone regions.