The Impacts of Post-Fire Straw Mulching and Salvage Logging on Soil Properties and Plant Diversity in a Mediterranean Burned Pine Forest

Abstract

In the Mediterranean forests, wildfires and post-fire management actions may degrade soil properties and negatively impact vegetation characteristics. These effects may reduce soil functionality and result in loss of plant diversity. Although straw mulching and salvage logging are commonly carried out in burned forests, their impacts on respiration of forest soils as well as on species richness and evenness of forest plants have been little explored. To fill these gaps, this study has evaluated the soil respiration, different soil physico-chemical properties, as well as plant diversity in a forest of Castilla La Mancha (Central Eastern Spain), burned by a wildfire and then subjected alternatively to salvage logging or straw mulching or to both techniques. Compared to the unburned soils, immediately after the fire mulching and salvage logging alone increased (+146%) and reduced the soil respiration (−9%), respectively, the latter especially in combination with mulching. However, these differences decreased over time, and the mulched and non-logged areas always showed the maximum soil respiration. The post-fire treatments also significantly influenced the main physico-chemical properties of the experimental soils. No evident changes were found for the pH of the logged and mulched soils compared to the control. Mulching coupled with logging did not modify the OM increase due to fire, while the lowest increase was measured in the logged but non-mulched areas. Mulched and non-logged soils maintained high OM and TN one year after fire, but also in areas that were treated with logging (with or without mulching) these parameters were significantly higher compared to the unburned areas. Mulching increased the species richness and evenness, especially when itis carried out without logging, in comparison to the unburned areas. Logging without mulching did not exert negative impacts on plant biodiversity, whose species richness increased and evenness was unvaried compared to the burned and unburned areas. The results of this study can provide land managers easy to measure tools such as soil respiration and plant diversity, which can serve to assess and evaluate the effectiveness of management measures that are taken post-forest fire in order to conserve the delicate ecosystems of the Mediterranean forests.