Climate effect on tree-ring widths of Fagus orientalis in the Caspian forests, northern Iran

Abstract

ABSTRACTThis study aims at understanding the impacts of climate factors on the annual growth variations of oriental beech (Fagus orientalis Lipsky) at the Kheyrud Forest Research Station located in the Caspian forests of northern Iran. To this end, 18 disc samples were randomly taken from altitudes of 1038 to 1152 m above sea level. Tree rings were measured using TSAP-win software and a LINTABII machine. Since false and missing rings are typical in beech trees, skeleton plots were created to enhance crossdating accuracy. Chronologies were observed for a total of 15 samples. Meteorological data for rainfall and air temperature were recorded at the Nowshahr Meteorological Station, located near the study sites. Results showed a significant correlation between mean annual air temperature and radial growth (R = 0.54). Within the growing season, August temperatures reveal a significant correlation with tree ring (R = 0.41) while the highest association was observed in the previous December (R = 0.44) and the least association was found in February (R = 0.31). Excluding March (R = 0.33), there appeared to be no significant correlation between precipitation accumulated during and prior to the growing season and tree ring. In addition to oriental beech, there are many other species important to this region that may be sensitive to increasing temperatures.