Are current post-fire management practices delaying natural regeneration in Pinus sylvestris mountain forests of the Aosta Valley (NW Italy)?

It is frequently believed that a post-fire environment requires immediate actions in order to be restored. Salvage logging and artificial afforestation are common post-fire restoration practices in many forests of North-western Italian Alps, following the misconception that any high severity disturbance destroys forest ecosystems and should thus be remediated. Aosta Valley is a mountainous region located in the north-western part of Italy. Its fire regime is characterized by a winter-early spring fire season, with low severity surface fires. An increase in size and intensity of wildfires has been observed over the last decades, with a higher number of large, severe crown fires, usually spreading within Scots pine (Pinus sylvestris L.) forests. The objectives of this study were to assess the impact of active and passive management on the restoration of a burned area of the Aosta Valley and to determine which approach is the most suitable for enhancing Scots pine regeneration after stand replacing wildfires. The influence of five management options (no intervention; salvage logging; broadleaves afforestation; larch afforestation; Scots pine or Douglas fir afforestation) and environmental variables on natural regeneration structure and composition was evaluated through direct gradient analysis. Spatial patterns of regeneration were characterized through Point Pattern Analysis indices.Pinus sylvestris and Populus tremula were the dominant tree species (40% and 29% respectively) in the regeneration layer. Density, size, and structural diversity of natural regeneration were higher in the no intervention area. The proximity to forest edge was found to be the most important environmental variable. Steep slopes, mostly near the forest edge, characterized by bare soil or shrub cover emerged to be favorite sites for Scots pine saplings. Salvage logged, non planted areas presented a very low natural regeneration density, associated with a dense herb layer. Natural regeneration structure was significantly influenced by post-fire restoration activities. Natural regeneration revealed a clumped distribution in most plots (75%). The abundance of downed deadwood in unsalvaged areas may have contributed to providing favorable sites for regeneration establishment, given the characteristics of high insolation and low precipitation of the studied area.Post-fire management activities were associated with significant mortality of natural regeneration. They interfered with natural succession processes, delaying regeneration development and altering its structure.This study provided evidence that taking advantage of natural restoration processes could be a preferred strategy in mountain P. sylvestris forests of the Aosta Valley, being cost-effective and promoting a greater diversity of structure and species.