Fire and Erosion: Evaluating the Effectiveness of a Post-Fire Rehabilitation Treatment, Contour-Felled Logs

Recent fires have renewed interest in the effect of fire on flooding, sedimentation and effectiveness of various mitigation techniques. Erosion is a natural process occurring at varying rates and scales depending on soil type, topography, vegetation, climate and type of disturbance. Erosion rates in a forest environment are generally small except when the ground surface is disturbed by human or natural causes. First year surface erosion rates after wildfire can vary from 0.1 to greater than 110 Mg ha^–1 yr^–1, often decreasing by orders of magnitude in subsequent years. Wildfires may consume the forest floor, leaving the soil surface exposed to raindrop impact and overland flow. Additionally, wildfires may leave the soil surface in a water repellent condition, reducing infiltration and increasing overland flow. These highly erosive conditions are temporary, because natural and artificial revegetation occur within first two years after the fire. To control this erosion and flooding potential, post-fire rehabilitation treatments such as contour-felled logs, have increased in use during the last decade.