Changes in soil functionality eight years after fire and post-fire hillslope stabilisation in Mediterranean forest ecosystems

Contour-felled log debris (CFD) and log erosion barriers (LEB) are two restoration practices used worldwide on hillslopes to avoid soil erosion after wildfires. Although significant work has evaluated the effectiveness of these practices on soil loss prevention, their effects on soil properties have been little researched to date. Here, the effects of CFD and LEB treatments on several physico-chemical and biological soil properties were investigated across four post-fire zones in Mediterranean forest (Sierra de Los Donceles, Spain). Results suggest that post-fire management similarly altered the recovery of microbiological soil properties and soil functionality for both CFD and LEB treatments. Post-fire management enhanced soil organic matter (SOM) and basal respiration, while suppressing soil microbial activities. SOM enhancement at our plots may have been associated with suppressed soil microbial decomposition activity due to post-fire increases in electrical conductivity. Plots with post-fire management recovered microbiological soil properties better than unmanaged burn plots, but not to the same level as nearby unburned plots. LEB and CFD may not only be effective in retaining sediments, but also in improving post-fire microbiological soil properties in comparison to unmanaged plots. However, after eight years of post-fire management, soil microbiological soil properties did not completely recover compared to unburnt areas. That is, fire may shift the development trajectory of microbiological soil properties so that they may no longer be able to return to the same unburnt conditions. Post-fire restoration plans should consider the use of LEB and CFD when aiming to aid soil-related ecosystem recovery processes after wildfires.