Potential for a 300-year drought reconstruction in the Zagros Mountains, Iran based on the tree-ring width of Quercus brantii Lindl.

Drought significantly affects the growth and physiological responses of Zagros forests, one of the most important natural habitats in Iran. The Brants oak (Quercus brantii Lindl), a widely distributed and dominant tree species in the Central Zagros Mountains of western Iran, serves as a valuable natural archive for studying historical climate variability and ecological changes. For climate-growth analysis, 30 Q. brantii trees cored from Lordegan area (1820 to 2280 m a.s.l.) in the southwest of Zagros forests of Iran. After preparing the samples, measuring the tree ring widths and cross-dating developed the tree ring chronology (1710-2023) using dplR. The relationships between tree-ring widths (TRW) and monthly mean temperature and precipitation values and the Standardized Precipitation Evapotranspiration Index (SPEI) were analyzed. The strongest climate signal of SPEI was found from previous September until April, representing the pre-growing and early-growing seasons. Among these reconstructions were acknowledged extremely narrow rings in 1870, 1923, 1960, 1964, and 2018, while extremely large rings were found in 1784, 1852, 1957, and 1976. Based on preliminary calculations showing a strong winter SPEI signal, this chronology could be used for climate reconstruction, but further analysis is required. These studies indicate the vulnerability of oak forests in the Zagros Mountains to ongoing climate change and a pressing need for sustainable forest management strategies to preserve these vital ecosystems.

 Keywords: Zagros forests, Iran, Quercus brantii, reconstruction, tree-ring widths