Modelling the effect of soil burn severity on soil erosion at hillslope scale in the first year following wildfire in NW Spain

Fire severity is recognized as a key factor in explaining post-fire soil erosion. However, the relationship between soil burn severity and soil loss has not been fully established until now. Sediment availability may also affect the extent of post-fire soil erosion. The objective of this study was to determine whether soil burn severity, estimated by an operational classification system based on visual indicators, can significantly explain soil loss in the first year after wildfire in shrubland and other areas affected by crown fires in northwest (NW) Spain. An additional aim was to establish indicators of sediment availability for use as explanatory variables for post-fire soil loss. For these purposes, we measured hillslope-scale sediment production rates and site characteristics during the first year after wildfire in 15 experimental sites using 65 plots. Sediment yields varied from 0.2Mgha(-1) to 50.1Mgha(-1) and soil burn severity ranged from low (1.8) to very high (4.5) in the study period. A model that included soil burn severity, annual precipitation and a land use factor (as a surrogate for sediment availability) as explanatory variables reasonably explained the erosion losses measured during the first year after fire. Model validation confirmed the usefulness of this empirical model. The proposed empirical model could be used by forest managers to help evaluate erosion risks and to plan post-fire stabilization activities. Copyright (c) 2015 John Wiley & Sons, Ltd.