Do alter post-wildfire straw mulching application and salvage logging pine natural regeneration after wildfires?

Mulching application and salvage logging are often performed in forests after fire to recover timber values and avoid soil erosion. These post-fire practices are believed to positively and negatively impact soil properties and initial seedling recruitment or seedling growth in pine stands. Mulch may increase soil moisture and lower soil temperature, which thus promotes seedling recruitment, whereas logging operations may generate soil compaction and destroy seedlings. As Mediterranean forests are delicate ecosystems, and different pine species or contrasting microclimate conditions (semiarid vs. subhumid Mediterranean climates) can display several natural regeneration trends, we investigated whether mulching combined with logging significantly alters soil properties, initial seedling recruitment and seedling growth in burned Pinus halepensis (Lietor) and Pinus pinaster (A Gudiña) stands in the short term. Our results demonstrated that soil organic matter and total nitrogen were the only soil parameters affected by treatments at site Liétor. Monitoring activity confirmed that regardless of tree felling or not, mulch treatment improved seedling density in the short term with a semiarid Mediterranean climate. At Liétor, seedling density was over 40% higher when mulching was applied, whereas aerial seedling length was the only seedling variable affected by this treatment. Conversely, the mulching+logging combination showed the highest seedling density, which could be related with more light availability after tree felling and the almost null effect of employed logging machinery. The harsh conditions at Liétor due to the limited water and light demands of pine species when water resources were ensured at site A Gudiña could be decisive for understanding the effect of mulching and logging operations for initial seedling recruitment. Our results generally suggest short-term soil changes and contrasting initial seedling recruitments after mulch and logging in burned semiarid and subhumid Mediterranean pine forests.