Wildfires represent the main natural hazard affecting forests and woodlands, with more than 3 million km2 burned worldwide each year. Although their most obvious impact is the complete or partial destruction of the vegetation, soil properties and functions are also modified in a variety of ways depending on burn severity. Wildfires can affect soil properties both directly through the impact of heating on mineralogical, physical, chemical and biological properties, and indirectly by removing the protection of the tree canopy and litter on the forest floor.
The changes to soil properties and vegetation typically lead to considerably increased runoff and erosion relative to long unburned terrain. In the post-fire period, mitigation treatments can help to prevent significant flooding, and to limit the occurrence of major soil erosion events and water supply pollution both close to settlements and in more remote areas.
The aim of this interdisciplinary session is to present, discuss and clarify the range of effects of burning at different fire severities on soil properties and hydrological processes and to examine both the traditional and recently developed types of mitigation treatment. Emphasis will be placed on:
• The impact of fire on different soil hydrological properties in a range of climates.
• The spatial and temporal characteristics of overland flow and soil erosion during the post-fire period.
• How soil properties altered by fire (e.g. soil water repellency, aggregate stability) affect post-fire overland flow and erosion patterns?
• Traditional and innovative methods for limiting flooding and erosion during the post-fire period.