Impacts of climate change on the wild olive ( Olea europaea subsp. europaea var. sylvestris ) in the Mediterranean Basin

Climate change is expected to affect the distribution of Mediterranean plant species, including Olea europaea var. sylvestris (wild olive), a keystone species for regional biodiversity and an important genetic resource for cultivated olives. Understanding how its range may shift under future climatic conditions is therefore critical for both conservation planning and the resilience of the species. In this study, an ensemble species distribution model combining generalised linear models, generalised additive models, and maximum entropy was used to assess the current and future climatic suitability of O. europaea var. sylvestris across the Mediterranean Basin under two Shared Socioeconomic Pathway climate change scenarios: SSP2–4.5 and SSP5–8.5. A total of 558 verified presence records were compiled, including 479 records obtained from the Global Biodiversity Information Facility and 79 records from regional herbaria, and combined with six bioclimatic variables. These variables were selected based on their ecological relevance and supported by Pearson correlation analysis. Current projections indicate high habitat suitability in the Iberian Peninsula, southern Italy, North Africa, and coastal areas where suitability persists across scenarios. However, all future projections reveal a reduction in suitable area, most pronounced under SSP5–8.5 for the period 2061–2080, accompanied by a clear northward shift in favourable habitat. These findings demonstrate that future climatic conditions are likely to substantially reduce the climatic suitability of O. europaea var. sylvestris , thereby increasing its ecological vulnerability. Reducing greenhouse gas emissions and promoting sustainable land management remain essential to slowing the pace of habitat loss and supporting the long-term persistence of wild olive populations.