The hydrological effects of straw mulching and salvage logging have been widely experimented in the Mediterranean forests affected by wildfires. In contrast, knowledge about the impacts of these post-fire management techniques on the physico-chemical properties of burned soils is poor, especially many years after the fire. In particular, no studies have evaluated the soil changes after the combinations of soil mulching and salvage logging after wildfires in Mediterranean forests. To fill this gap, this study explores the effects of straw mulching and salvage logging, applied individually or in combination to a burnt forest of Pinus halepensis Mill. of central-eastern Spain, on the physico-chemical properties of soil six years after a wildfire. Both the post-fire techniques significantly altered the organic matter, phosphorous, and carbonate contents of the burned soils as well as their C/N (carbon/nitrogen) ratio, while the texture and other chemical properties (pH, electrical conductivity, total nitrogen, potassium, cations/anions, and active limestone) of the soils were not significantly affected by these post-fire treatments. Organic matter (OM) and phosphorous (P) contents increased by 57% and 69%, respectively, in mulched soils in comparison to the burned but untreated plots. In logged soils, the OM increased by 27%, while P decreased by 17%. Salvage logging after straw mulching increased OM, albeit less than under the individual soil treatments (+13%), but noticeably reduced P (−39%). The C/N ratio practically underwent the same variation (+15–20%) after the combination of the two treatments. The principal component analysis and the agglomerative hierarchical cluster analysis applied to the soil properties measured in the plots under the individual and combined management show that the effects of salvage logging on soil properties appear to be more impactful compared to straw mulching.

Straw mulching and salvage logging are common management techniques after forest wildfires. However, these post-fire actions may result in an additional disturbance in burned soils, which may hamper the natural regeneration of forest species, especially in Mediterranean areas. The results of the investigations on the impacts of these post-fire management techniques are still insufficient, and especially about post-fire regeneration of Pinus halepensis Mill. This tree species is typical of the western Mediterranean Basin and is hardly threatened by forest wildfires. To fill these literature gaps, this study explores the effects of salvage logging after straw mulching on the regeneration of Pinus halepensis Mill. throughout four years after a wildfire. These effects have been also related to the changes in the main chemical properties of the supporting soils. Compared to the burned but non-treated areas, after four years of fire and post-fire treatments, we found that: (i) mulched and non-logged sites showed a significantly higher number of seedlings (+66%) with larger diameter (+12%) and higher height (+25%); (ii) logging did not significantly increase this number (+74%), but, in mulched and logged sites, the seedlings had significantly lower diameters (−18%) and heights (−9%); (iii) an increase in the seedling number (+29%), and decreases in the plant diameter (−34%) and height (−15%) were observed in the non-mulched and logged areas; (iv) no significant differences in the other morphometric parameters of seedlings were detected among all post-fire treatments; (v) a clear gradient between the organic matter content of soils and the number of plants growing under the four treatments was evident. These results support the task of forest managers in accelerating the recovery of natural vegetation in burned pine forests in the Mediterranean environment.

To avoid flooding and erosion hazards, post-fire management actions are essential in Mediterranean forests after severe wildfires. In this regard, mulching is the most common action but some mulch materials, such as straw, may lead to adverse impacts in burned forests. The use of yellow mistletoe fruits (Loranthus europaeus Jacq., hereafter “LE”) for the production of biodegradable mulch and its effectiveness in post-fire hydrology have never been studied. To fill this gap, this study has evaluated surface runoff and rainsplash erosion in a pine forest in Central Eastern Spain burned by a wildfire and mulched by a mixture of LE fruits and straw (with or without adding clay particles) using a portable rainfall simulator. Compared to untreated sites, runoff increased in burned and mulched soils (by 13.6% for the mixture without clay and by 17.2% when clay was added, in the latter case significantly). This increase was mainly due to the compact layer created by mulch application on the soil surface. However, the peak flow and the time to peak were lower in mulched soils (on average by 32.7% and 60.5%, significantly only for the mulch mixture without clay), thus indicating that, in these soils, peak runoff takes longer and its maximum value is lower compared to untreated sites. Soil erosion noticeably and significantly decreased (up to 97%) in mulched areas in comparison to untreated sites without significant differences between the two mixtures. Overall, this study indicates to land managers that soil mulching with a mixture of Loranthus europaeus Jacq. and straw is an effective post-fire management action to reduce the soil erosion risk after a wildfire.