Hydrological evaluations and effects of climate on the radial growth of oriental beech (Fagus orientalis lipsky) in Abdipaşa, Bartın, Turkey

Based on a 41-year-long (1978-2018) ring-width chronology (rwi), we have determined the main climate variables affecting the radial growth of oriental beech trees (fagus orientalis lipsky) and the correlation coefficients between rwi and the streamflow drought index (sdi) of the kocaırmak river in northwestern turkey. higher average maximum temperatures (t_max) in june caused decreased radial growth (r = -.34, p < .05), whereas higher total precipitation (p_rep) in the same month caused increased radial growth (r = .29, p < .05). moreover, the mean and minimum temperatures (tmean and tmin) in december of the previous year caused increased radial growth (r = .27 and .32, respectively, p < .05). compared to period 1 (1978-1996), there was a significant relationship between rwi and climate variables (p_rep and t_max in june and t_mean and t_min in december) for period 2 (1997–2015). moreover, significant correlations were obtained for february (r = .41, p < .05), june (r = .51, p < .01), and august (r = .44, p < .05) between rwi and sdi_1 (1-month sdi), which indicates that radial growth was reduced in the years with negative sdi_1 values in february, june, and august. similarly, significant correlations between rwi and sdi_3 (3-month sdi) for july–september (r = .51, p < .05) and june– august (r = .57, p < .01) indicated the reduced radial growth in the years with negative sdi_3 values.