Factors affecting natural regeneration of woody vegetation following severe fire in Pinus nigra forests: a year zero assessment

Pinus nigra (black pine) is an ecologically important species in the Mediterranean Basin. Black pine plantations were established in the early 20th century to prevent soil erosion in mountain environments around Italy. The unmanaged pine stands tend to develop an understory of broadleaves, including Quercus ilex, Ostrya carpinifolia, Fraxinus ornus, Acer spp., and Quercus spp. As fire increases in frequency and severity in the Mediterranean Basin, these already endangered habitats are increasingly at risk. This study aims to investigate the role of biological legacies and topographic factors that affect the natural regrowth of woody vegetation following severe fire in montane Pinus nigra forests. Pinus nigra lacks fire-specific adaptations such as serotiny, resprouting, or a seed bank. This year-zero study of regeneration of woody vegetation will help highlight what topographic factors and material legacies best support regrowth immediately after fire and provides insight into the future makeup of the postdisturbance community. Legacies and topography that regulate temperature extremes, soil moisture, and soil temperature created microsites that were conducive to increased regeneration density and greater performance of woody regeneration. Regenerative strategies—obligate reseeding, obligate resprouting, and facultative seeding—were analysed to determine which strategy was most successful in specific microclimatic conditions immediately after severe fire.