Investigation of the Effects of Roudbar and Manjil Earthquake on the Growth of Cupressus sempervirens Var. Horizontalis Trees, Using Dendrochronological Methods

Todays, analyzing the effects of earthquakes on tree growth became possible by using dendrochronological methods. This study is done by the aim of investigating the effects of the severe Roudbar-Manjil earthquake in 1990 on the growth of Cupressus semperviren trees in Rudbar county. For this purpose, after obtaining a license to cut down eight Cupressus trees in Roudbar city, the trees were randomly selected; cut down and eight discs were taken from their diameter at breast height. Also, in order to investigate the effects of climatic factors, 30 years (1983-2012) temperature and precipitation data of the region were received from Manjil synoptic station. Preparation of images of research disks slices with 2mm thickness were done using, medical radiology device and comparative dating, estimation of reliability components, chronological analysis of data, plotting and correlation between growth and climatic factors were performed using Mini-Viewer, ARSTAN, Excel and Spss software's. In addition, release and suppressed growth of trees in the five year after earthquake period were calculated, using growth change equations. The results showed that there was no correlation between tree growth and temperature factor (r = 0.21); While the correlation of precipitation factor with tree growth during 30 years was positive (r = 0.809) and during the years (1991 to 2000) was negative (r = - 0.72). Therefore, the growth changes of this species, which increased in the first five years after the earthquake and decreased in the second five years, can be related to the effects of the earthquake on trees. On the other hand, Cupressus semperviren was recognized as an earthquake-resistant species because the growth of suppression in the studied disks did not show a significant difference with the release growth.