Comparison between the Effects of Temperature and Solar Radiation on Growth of Quercus castaneifolia C. A. Mey. in Astara Forests using the Dendrochronology Method

Due to variances in response of different tree species in different habitats to climate changes, further studies in this field is clearly required. On the other hand, the lack of studies on chronology to evaluate the effect of solar radiation on radial growth of tree species due to lack of long term data of an important climatic variable, new approaches to determine the effect of this parameter on growth diameter is inevitable. The main objective of this study was to evaluate the effect of temperature and irradiance climatic parameters on growth of diagonal oak (Quercus castaneifolia) as one of the main tree species of forests in Iran. For this purpose, 17 harvested Quercus castaneifolia disks from trees in Astara forest were used and chronology of the species and the response of radial growth to temperature and radiation climatic variables were studied. The findings revealed that although the chronology obtained from two perpendicular directions of each disk for 15 disks had the desired result but the chronology obtained from the 15 selected disks with each other reflected the fact that only 10 disks had acceptable results for chronology of Quercus castaneifolia in Astara forest. Results also revealed that both temperature and solar radiation parameters had negativly significant effect on growth of Quercus castaneifolia. The correlation coefficient (R) between the radial growth and these two variables was -0.52 and -0.45, respectively. Therefore, it can be concluded that although both solar radiation and temperature have a negative effects on growth of Quercus castaneifolia, the temperature is more important than radiation. This fact can be related to cloudy condition of weather in the north part of Iran.