Growth Responses of European Beech (Fagus sylvatica L.) and Oriental Beech (Fagus orientalis Lipsky) Along an Elevation Gradient Under Global Climate Change

European beech (Fagus sylvatica L.) and Oriental beech (Fagus orientalis Lipsky) are ecologically and economically important tree species in European and western Asian forests, which are currently significantly affected by global climate change. To assess their response to climate variability, tree-ring data from 12 permanent research plots (PRPs) were analyzed in Central Europe and Turkey, covering an elevational gradient from 360 to 1430 m above sea level (a.s.l.). Using 360 tree cores, the relation between air temperature, precipitation, and climate-related stress on radial growth was investigated, alongside production potential and carbon sequestration. The results show that European beech is more sensitive to both air temperature and precipitation than Oriental beech. Carbon sequestration of forest stands ranged from 37 to 361 t·ha−1 depending on the elevational gradient, with European beech storing, on average, 33.1% more carbon than Oriental beech stands. Radial growth was related to both air temperature and precipitation, with the strongest effects observed at mid-elevations (740–950 m a.s.l.). In European beech, both current and previous year temperatures significantly related to growth, whereas in Oriental beech, only the current year was critical. July was the most influential month for tree growth in both species. On PRPs located at lower elevations, radial growth over the past 20 years decreased by 13.1%–19.3% compared to the previous 20-year period, whereas in mountainous areas, it increased by 5.6%–9.8%. Low precipitation during the growing season was the main limiting factor for growth in lowland areas, whereas low temperatures were the primary constraint in mountainous regions, and vice versa. In recent years, the frequency of negative pointer years with extremely low radial growth has been increasing, reflecting a rising occurrence of climate extremes. These findings highlight species-specific climate sensitivities, emphasizing the importance of adaptive forest management strategies for mitigating global climate change impacts and increasing carbon sequestration.