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 À1 ), wood-chip mulch (4 Mg ha À1 ), 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-m 2 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 À1 . 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 À1 respectively, were similar to rates in the untreated plots (35 Mg ha À1 ). 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.

Comparing the effectiveness of seeding and mulching+seeding in reducing soil erosion after a high severity fire in Galicia (NW Spain)

“…However, previous studies in NW Spain (Fernández et al, 2011;Vega et al, 2014) have shown that total precipitation was more closely correlated with post-fire soil erosion than rainfall intensity. This contrasts with the findings of the present study, possibly due to the lower precipitation than in the above-mentioned studies.…”

“…In another study conducted after a very severe wildfire in a shrubland in Galicia, in an area with higher precipitation, Fernández et al (2011) observed that the effectiveness of straw mulch was 66%. This suggests that the efficacy straw mulch may decrease with increasing soil burn severity and precipitation.…”

“…One of the most serious ecological consequences of forest fires is the increased soil loss via erosion (Benavides-Solorio and MacDonald, 2005;Spigel and Robichaud, 2007;Fernández et al, 2011). The combustion of the vegetation and ground cover exposes the mineral soil to raindrop impact and reduces its infiltration capacity (De Bano et al, 1998;Neary et al, 2005;Shakesby, 2011).…”

“…The underlying rationale is that under a warm and rainy climate, such as prevails throughout most of NW Spain, grass becomes established quite rapidly, thus contributing to a substantial degree of soil cover. Other treatments, such as mulching, yield ground cover instantaneously, and have proved suitable for reducing soil loss after fire in Galicia and elsewhere (Bautista et al, 1996;Wagenbrenner et al, 2006;Fernández et al, 2011;Prats et al, 2012;Fernández and Vega, 2014;Vega et al, 2014).…”

Soil gross N transformation rates after a wildfire and straw mulch application for burned soil emergency stabilisation

“…One of the most useful BAER techniques is mulching, usually with straw, that greatly reduces soil losses (Bautista et al 2009;Díaz-Raviña et al 2012;Fernandez et al 2011;Groen and Woods 2008;Vega et al 2014), but the available information on their effects on burned soil quality and fertility is still scarce Fontúrbel et al 2012;. Although it is wellknown that mulching modifies the environmental conditions and the organic matter dynamics in soils, including gross N transformations (Cheng et al 2012;Huang et al 2008), there are no studies dealing with the effects of post-fire mulching treatments on N dynamics.…”