Effectiveness of three post-fire treatments at reducing soil erosion in Galicia (NW Spain)

Abstract

This study assessed the effectiveness of different methods of reducing soil erosion after a severe wildfire in Galicia (NW Spain). The treatments compared were: straw mulch (2.5 Mg ha–1), wood-chip mulch (4 Mg ha–1), cut-shrub barriers and control. Straw mulch provided an initial ground cover of 80% and the wood chips only 45%. Sediment yields were measured by means of sediment fences in 500-m2 bordered plots. During the first year after wildfire, mean precipitation was 1520 mm. The mean sediment yield in the control plots was 35 Mg ha–1. During this period, only straw mulch application significantly reduced soil erosion relative to controls (66%). The mean sediment yields in the wood-chip mulch and erosion barrier treatments, 33 and 30 Mg ha–1 respectively, were similar to rates in the untreated plots (35 Mg ha–1). Soil erosion decreased sharply during the second year after wildfire when mean precipitation was 1194 mm. Vegetation regrowth was very fast and treatments had no significant effect on the rate of recovery of vegetation cover, which was ~80% at the end of the study. The results obtained showed that ground cover was a key factor in determining post-fire soil loss. Stabilisation treatments such as wood-chip mulch and erosion barriers were not effective in reducing soil loss relative to the untreated control.