Fuel-reduction thinning enhances Scots pine growth during the 2022 drought in the south-western Alps

Scots pine (Pinus sylvestris L.) is one of the most widely distributed conifers in Europe, thanks to its pioneer traits and adaptability to diverse environments. Over the past two decades, Scots pine forests have been increasingly exposed to multiple disturbances such as drought, dieback and wildfires. Silvicultural interventions such as intensive thinning may reduce fire hazard while increasing individual tree resistance to drought, thereby slowing dieback processes. Here, we investigated the short-term effects of pyro-silvicultural treatments carried out in spring 2022, followed by a summer drought, in Scots pine stands of the south-western Italian Alps. We also evaluated tree climate sensitivity. Crown transparency and radial growth were analysed in three thinned areas and compared with an unthinned control. Field sampling was conducted in winter 2023/2024, selecting 34 trees per area based on diameter and competition index. Results show that retained trees did not experience growth reduction during the 2022 drought and exhibited a higher recovery than trees in the control stand. In contrast, during the pre-treatment 2003 drought, all study areas showed comparable growth reductions, indicating similar drought sensitivity before thinning. Competition negatively affected radial growth, while higher crown transparency, more pronounced in the control area, was associated with smaller diameters. Younger trees (<90 years) exhibited lower growth than older individuals (90–185 years), particularly in the control area. Radial growth and latewood density (inferred from blue intensity) were positively correlated with May and May–June precipitation, respectively. Overall, two years after fuel-reduction thinning, reduced competition enhanced short-term growth response, supporting pyro-silvicultural treatments as a promising strategy to simultaneously reduce wildfire hazard and improve the short-term drought resilience of retained Scots pine trees.