Wildfire effects on soil erodibility in Galicia

Soil erodibility exerts a decisive influence on the severity of water erosion resulting from forest fires. This paper reports the results of various experiments conducted on soils inGalicia(NW Spain) with a view to identifying the main soil properties governing soil erodibility, as well as the impact of forest fires on this property and the consequences of the ensuing changes on thehydrological and erosive response of soil. By virtue of their predominantly coarse texture, high contents in organic matter and also high aggregate stability, soil forests inGaliciaare scarcely erodible. Because the impact of forest fires on their erodibility depends on these soil properties, it is also markedly dependent on fire severity. Soil erodibility seems scarcely affected by low-severity fires but increases markedly with increasing severity. The water repellency of soil, whether induced or boosted by fire, is a determining factor for the occurrence of runoff and erosion processes continually observed in burnt areas in NW Spain.