UBC Undergraduate Research

The effect of fire on forest soils and hydrologic responces : a review Hallaway, Marissa

Abstract

The goal of this review was to investigate the correlation of wildfires with decreased infiltration and increased runoff. Research suggested that wildfires can alter several forest soil properties affecting infiltration and runoff, including the formation of a fire-induced water repellent layer, the addition of a surface ash layer, and the removal of surface cover. The combination of these effects can lead to serious hydrologic and geomorphic events such as flooding, large-scale erosion and water sedimentation problems. The pre-fire soil condition is a determining factor to the overall influence of the fire, in particular, soil moisture content and amount of soil organic substances. Soil moisture content can either promote heat transfer or prevent extreme high temperatures depending on its level. Soil temperature combined with the amount of soil organic substances determines the strength of the fire-induced water repellent layer within the soil profile. Ash was found to have somewhat contradicting short-term effects with respect to infiltration and runoff. It is either seen as a natural way of mitigating water repellency and loss of surface cover by increasing infiltration capacity and protecting underlying mineral soil from raindrop impact. However, some studies also suggest that it adds to reduced infiltration by causing soil sealing. The case study from South Interior Forest Region of British Columbia describes a Risk Analysis report for the Sitkum Creek Fire (number N70347) in 2007 that includes useful management strategies developed to mitigate the effects of wildfire in community watersheds.

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Attribution-NonCommercial-NoDerivatives 4.0 International

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