Effects of post-fire application of straw mulch strips on soil erosion, soil moisture and vegetation regeneration in European dry heathlands in NW Spain

Abstract

Applying mulch to severely burned soils is common practice in fire-prone areas such as the NW Spain. Mulch that provides >80% cover can reduce post-fire soil erosion by up to 90%; however, this level of cover can sometimes be difficult to achieve in remote areas due to the logistic constraints. Although application of mulch strips is a possible alternative approach, there is no information available about the effectiveness of this technique. Such information is critical in protected areas where mulch application can modify the recovery of natural vegetation by altering the soil moisture regime.In this study, the effects of the application of 20 m wide straw mulch strips on soil erosion, soil moisture and vegetation recovery were assessed during the first year after a high-severity fire that occurred in September 2020 in two European dry-heathland areas.During the first year after the fire, the mean sediment yields in the untreated plots were 18.5 Mg ha−1 and 33.8 Mg ha−1, respectively at the Lobios and Vilariño study sites. Although the straw mulch strips reduced soil erosion by >70% on average, erosion rates remained high at both sites. Soil moisture contents in mulch-treated areas were significantly higher than in untreated areas during spring and summer.Mulching affected vegetation recovery in different ways, i.e., it had neutral to positive effects, depending on the study site. No alteration in species composition was observed in either of the sites as a result of treatment application.In summary, the reduction in soil erosion after the application of straw mulch strips covering 67% of burned soil under the conditions of the present study under the conditions of the present study reduced a 70–75% of soil erosion after a high-severity wildfire.