Past projections of submediterranean oaks unveil future range shifts of vulnerable taxa under climate change

Abstract

Abstract Submediterranean marcescent oak forests form a climatic ecotone highly exposed to increasing aridity across the Mediterranean Basin. Understanding how these vulnerable taxa were affected by past climatic shifts can help contextualize their sensitivity to ongoing changes. Here we used ensemble Species Distribution Models (SDMs) to infer the distribution dynamics of eight marcescent oak species from the Heinrich Stadial (~ 17 ka) to the present, and to explore their potential future trajectories for 2070 and 2100 under three SSP scenarios. Models calibrated with 12,450 filtered occurrences and high-resolution paleoclimate and CHELSA datasets performed well (AUC > 0.97), with precipitation and temperature seasonality emerging as key predictors. Hindcasts revealed contrasting east–west Quaternary histories, including episodes of expansion, contraction and partial stability linked to abrupt climate transitions such as the Heinrich Stadial and Younger Dryas. Future projections indicate widespread northward shifts and substantial suitability losses, especially under SSP5-8.5, with pronounced impacts on narrowly distributed taxa. By comparing past-to-present and present-to-future range shifts, we identify temporal coherence in species responses, showing that taxa with strong historical fluctuations tend to exhibit larger projected changes. Integrating past range dynamics provides an essential ecological baseline to interpret species-specific sensitivity and regional asymmetries. Our results refine the identification of potential climatic refugia and high-risk zones, offering a framework to prioritize conservation strategies for transitional oak forests in a rapidly warming Mediterranean Basin.