Growth-based resilience indices for drought responses of Persian oak (Quercus brantii Lindl.) along humidity gradients in the Zagros Mountains, western Iran

• Applicant: Dr. Mohsen Arsalani
• Subject Area: Forestry ; Physical Geography
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 520084158

During the last decades, the intensity, frequency and duration of droughts has especially increased in drought-prone regions, such as in the Middle East. This may challenge the sustainability and productivity of regional forest ecosystems. The proposed project uses growth-based resilience indices to analyze drought responses of native Persian oak (Quercus brantii) along altitudinal and humidity gradients in the Zagros Mts., Iran. Multiple intra-annual tree-ring parameters of Q. brantii including earlywood width, latewood width, earlywood and latewood basal area increments, stable carbon isotope ratios and quantitative wood anatomical parameters will be analyzed separately in earlywood and latewood. The climate relationships of all tree-ring variables and the physiological responses of the iconic tree species will be determined over the common period of the last 70 years (1953-2022) to identify the main climatic and environmental causes of the large-scale oak decline phenomenon in this climate change hotspot. Since the region is under control of two different circulation patterns during a year and different large-scale teleconnection patterns affect the study region during winter and summer, the intra-annual resolution of multiple tree-ring parameters provides more accurate information about changes in the ecological response of Persian oak towards changes in the seasonal climate conditions. Within the project framework, resistance, resilience and recovery indices of the species will be recognized along altitudinal and humidity gradients to identify the main seasonal climatic drivers responsible for the deterioration of tree vitality. This shall enable the regional stakeholders to develop science-based plans for protecting and sustainably manage the Zagros oak woodlands in the water-stressed region. The analyses of intra-annual dendroecological responses of the oak species to extreme drought events is useful for tree ecophysiological studies in the eastern Mediterranean region and can contribute to a better understanding of the mechanistic processes underlying tree mortality on a global scale.

• DFG Programme: Research Grants