Exploring turnover dynamics in Iberian Oak forests under climate change scenarios

Mediterranean forests have evolved over millennia under the combined influence of long-term climatic variability, which, together with natural and human disturbances, resulted in high heterogeneity of species composition and community structure. However, ongoing climate change, predicted to be particularly severe in the Mediterranean region, may threaten these forests and their biodiversity. In this work, we explore future trajectories of Iberian forests under climate change scenarios. We focus on three oak species predominantly associated with acidic substrates, Quercus suber L., Q. pyrenaica Willd. and Q. robur L., which dominate climax native forests with their optimal distribution ranges. To assess potential species turnover among focal species, we developed high-resolution spatial suitability models to project future habitat suitability for each species in the mid- and late-21st century under two climate change scenarios (SSP3-7.0 and SSP5-8.5). Results indicate different responses to climate change across species, reflecting distinct ecological thresholds, but all show predominant northward (latitudinal) and upward (altitudinal) range shifts. Projections indicate potential changes in the dominant forest species floristic composition of the Iberian oak forests’ tree layer in the future, marked by species turnover, with drought-tolerant species replacing moisture-dependent oaks across significant areas along existing environmental gradients. It is especially evident in turnover from Q. pyrenaica to Q. suber, particularly at current southern fringes and on inland areas of the Iberian Peninsula. Forest management must incorporate these projected changes through adaptive strategies, aiming to enhance forest persistence and resilience.