Summer aridity modulates tree growth response to thinning in Mediterranean pines

Forest management offers a proven tool for adapting forests to changing climatic conditions and mitigating their impacts. However, the interaction between forest management practices and climatic conditions in Mediterranean forests warrants further investigation. The primary objective of this study is to assess the combined impact of climate and thinning on secondary tree growth in Mediterranean pines. For the purposes of this study, we leveraged long-term forest information from nine thinning trials established in four Mediterranean pine stands, comprising two subspecies of Pinus nigra Arn. (Black pine subsp nigra and salzmannii ), Pinus pinaster Ait. (Maritime pine), Pinus pinea L. (Stone pine) and Pinus sylvestris L. (Scots pine). We found a significant, positive association between growth and thinning intensity and a negative relationship with summer aridity. Interestingly, our results revealed that the interaction between thinning and climate is species-specific but also site-specific for Scots pine. Overall, we concluded that thinning is a powerful tool for adapting forests to harsher climatic conditions in the Mediterranean Basin. However, the reduction in density may not be sufficient for forests to adapt when climatic conditions become extremely harsh. • Tree growth increased with thinning intensity and decreased with summer aridity. • Thinning–climate interactions were species- and site-specific for Scots pine. • Thinning helps forests adapt to harsher Mediterranean climates. • Density reduction alone may be insufficient under extremely harsh climates.