Ecological differentiation in Pinus nigra subspecies predicts differential responses to climate change

Abstract

Understanding the effects of climate change has become a global challenge since the second half of the twentieth century, with many studies focusing on trees due to their major role in ecosystem functioning. Pinus nigra J.F. Arnold is of particular interest, as it is a key component of European forests and holds significant value for forestry and afforestation. Although previous studies have addressed the taxonomy of this species at the infraspecific level, ecological differentiation among its subspecies remains unexplored. Here, we present an integrative framework to assess the relationship between P. nigra subspecies and climatic variables using both niche overlap analyses and Species Distribution Models (SDMs). This approach allows us to compare the climatic niches of the subspecies and evaluate potential risks for each under future climate change scenarios. Our results demonstrate that most subspecies occupy distinct climatic niches, exhibiting differences in the relative importance of climatic variables. Additionally, the predicted current potential distribution is broader than the known distribution. Future projections indicate substantial shifts in suitable habitats for all subspecies, with P. nigra subsp. nigra showing the greatest potential expansion, in contrast with reductions projected for most other subspecies. These results are of interest for stakeholders to manage future afforestation or assisted migrations, as well as provide new information for conservation planners, although models should be always interpreted with caution.