Reducing post-fire soil erosion from the air: Performance of heli-mulching in a mountainous area on the coast of NW Spain

Although heli-mulching is frequently used in North America to mitigate post-wildfire soil erosion, its use in other regions, at operational scale, is still very limited and, hence, information of its performance in different environments is lacking. In this study, we compared the effectiveness of straw heli-mulching to reduce soil erosion during the first two years after severe wildfire in Galicia (NW Spain). Seventy experimental plots (each 80 m2) were established in five forest areas that were severely burned in the summer of 2013. During the two years of study, the accumulated soil loss in the untreated burned soils ranged from 7.7 to 53.9 Mg ha− 1. Heli-mulching reduced soil loss by on average 90%. The variation in mulch cover in the first and second years after fire was significantly related to mean gust wind velocity. Soil burn severity and the mean dry mean weight diameter of soil aggregates were related to soil loss and modulated the effects of mulching during the study period. Vegetation cover did not protect against soil loss during the first year after fire, highlighting the need for emergency measures to be implemented immediately after fire to protect the soil from erosion.