Oaks and Climate Change: Contrasting Range Responses of Mediterranean and Temperate <i>Quercus</i> Species in the Western Palearctic

Over the Quaternary, the geographic distributions of many species have experienced shifts in response to climatic changes. We examined the range-shift patterns of six oak (<i>Quercus</i>) species occupying different climatic zones of the western Palearctic under both past and future climate conditions. Using ecological niche models, we reconstructed distributions during the Last Glacial Maximum (LGM, ~22,000 years before present), compared them to the Present, and projected future changes under two scenarios for 2081-2100 (SSP1-2.6 and SSP5-8.5). Quantitative metrics of latitudinal centroid movement, range limits, and area change revealed consistent contrasts among climatic groups. During the LGM, temperate (<i>Q. robur</i> and <i>Q. petraea</i>) and transition-zone (<i>Q. cerris</i> and <i>Q</i>. <i>pubescens</i>) species contracted strongly, persisting in southern refugia across Anatolia, the Balkans, and the western Mediterranean, whereas Mediterranean oaks (<i>Q</i>. <i>coccifera</i> and <i>Q. suber</i>) retained more stable ranges. Future projections suggest that temperate and transition-zone species will undergo substantial range loss and poleward shifts, particularly under the pessimistic scenario, whereas Mediterranean oaks will experience limited latitudinal shifts but pronounced expansion in to northern latitudes and temperate regions. These findings indicate Mediterranean oaks are ecologically distinct from temperate and transition-zone species, which show similar climate sensitivities. Our results emphasize the need for climate-zone-specific conservation strategies, including enhancing connectivity and genetic diversity for temperate and transition-zone species, and prioritizing drought-resilient populations and adaptive management for Mediterranean species, to support the long-term resilience of European oak forests under ongoing and future climate change.