Settlers in the aftermath: early regeneration in burnt artificial Pinus nigra forests through an altitudinal and latitudinal gradient

Forest fires appear as a destructive phenomenon, consuming years of vegetation growth in a little timespan. In addition, forest fires change the environmental conditions for years to come, sometimes permanently. On the other hand, fire has been present in some biomes for ages, and it will be surely a natural disturbance of tomorrow forests. Scientific knowledge has accumulated on forest fires and post-fire forest dynamics, but it is still difficult to predict what will happen to a burnt forest, especially today and in Europe: climate change is shifting the ground regarding forests dynamics, and information on long term post-fire forest dynamics are scant in Europe, due to the strong and long-lasting anthropic footprint. Increasing our understanding of post-fire forest dynamics is a first step to reduce disruptions in the provision of forest ecosystem services. The simplest way to study post-fire forest dynamics is to sample post-disturbance natural regeneration. Especially where fire burns with high severity (primary succession) species that arrive first will probably impose the forest composition for the next decades. Information on this dynamic is particularly relevant for artificial secondary forests, because little or no record may be available regarding their response to forest fires. In our study, post-fire natural regeneration was sampled in three artificial Pinus nigra J.F.Arnold forests burnt with high severity in 2012, 2017, and 2022, respectively. This species was extensively used for afforestation in Southern Europe, and nowadays black pine forests show similar dynamics and a high proneness to fires across all its areal. The three forests differ in altitude, latitude and climate, but have common traits, such as bedrock type, natural regeneration species and potential natural forest composition (nearby stands). Results show a clear transition from pine to broadleaves forests after fire, mainly due to resprouting. Black pine regeneration is present, but only where severity is low. Common trends across sites hint that general indications may be drawn, although the main intended contribution of our study is to propose an approach to study post-fire forest dynamics in areas with relatively short records of forest fires, such as artificial conifer forests in European mountains.