Climate sensitivity of Quercus macranthera Fisch. & C. A. Mey. at the high-elevation forest edge of the Alborz Mountains, N Iran

Alpine treelines mark the upper limits of tree growth in mountain ecosystems, with heat deficiency being the globally common abiotic driver. Controlled by low temperatures, tree growth at treelines will be responsive to above-average climate warming in the world’s high mountains. Trees at the high-elevation forest edge of the Alborz Mountains in northern Iran have rarely been used so far to study growth-climate relationships. While growth responses to climate change have been studied for several species in this region, the effects of climatic factors on Quercus macranthera Fisch. & C. A. Mey., particularly at the current upper tree limit, remain underexplored. This study investigates the dendroclimatology of Quercus macranthera , the dominant species at the high-elevation forest edge in the Alborz Mountains. We developed tree ring width (TRW) chronologies spanning over 400 years from three sites to investigate long-term relationships between tree growth and climate. The chronologies showed significant correlations with temperature and precipitation patterns. Radial growth was positively influenced by winter and spring temperatures and growing season precipitation. Drought stress, particularly in late summer and autumn, emerged as a key growth limiting factor. These results suggest that Quercus macranthera is sensitive to climate variability, with local factors such as topography and moisture availability modifying the sensitivity. This study highlights the potential impacts of climate change on high-elevation forests and sheds light on how Quercus macranthera may respond to future climate change.