Climate-Driven Shifts in the Distribution of Valonia Oak from the Last Glaciation to the Antropocene

Abstract

The Quercus genus is found across a broad latitudinal range, and its spread in heterogeneous ecosystems is influenced by environmental, genetic, and anthropogenic factors. However, Mediterranean oak ecosystems, in particular, have been significantly impacted by climate-driven shifts. These shifts reshape the composition and spatial configuration of a great number of species. Here, this study evaluates the impact of climate change on the habitat suitability of Valonia oak (Quercus ithaburensis subsp. macrolepis (Kotschy) Hedge & Yalt.) and particularly focuses on understanding whether its population is native or was introduced to the Karagüney Mountains, Türkiye. Using ecological niche modeling with MaxEnt and climate data from CHELSA-TraCE21k (a 1 km climate time series), we built 120 models to analyze the habitat suitability of Valonia oak across different climatic periods from the Last Glacial Maximum (LGM) (21 ka BP) to the present. The results indicate that habitat suitability is primarily influenced by temperature- and precipitation-related variables. In fact, temperature fluctuations clearly affect the target species of this study. The most significant factors are the mean diurnal temperature range (bio2; 33.1%), precipitation in the wettest month (bio13; 19%), and mean annual temperature (bio1; 16.7%). Paleoclimatic predictions show that suitable habitats contracted during the early Holocene but expanded afterward, with current distributions aligning more closely with the natural range. In other words, it can be stated that Valonia oak’s habitat suitability has gradually improved from the LGM to the present, with both the total and natural ranges expanding over time. The results indicate that the species has demonstrated long-term stability, resilience, and adaptability to climate change, making it a potential alternative species for future climate scenarios. In addition, the data support the hypothesis that the species’ population in the Karagüney Mountains is relict, but was previously unrecognized as native. This study improves our knowledge about the distribution and environmental preferences of Valonia oak, which is important for underpinning its conservation strategies.