The effect of climatic variables on annual tree-rings width of Persian juniper trees in Kyguran habitat of Lorestan province

Recent global warming had brought harsh variations on climate variables all over the world. In order to investigate the past climate trend for predicting future climate trend, long term climate data is needed. Tree-ring data are good proxies of past climate which can be used to reconstruct the past climate. The purpose of this investigation is to develop the chronology of tree-ring width and its comparison with climate variables. Tree-ring width was measured by LINTAB table. Then, measured tree-ring width was cross dated by TSAP software. To remove age trend and preparation of final chronology, the ARSTAN software was used. 12 out of 22 tree time series were dropped out, because of insufficient matches with the other samples. The final chronology of the site was determined from 1657 to 2014, close to 358 years. However, EPS was more than 0.85 only for the period of 1910-2014. Correlation between annual tree-rings indices and monthly precipitation was not significant. While monthly mean temperatures of January, February and March had positive and significant correlations with tree-ring widths. It could be concluded that Juniperus growth is not limited by moisture conditions while higher temperatures were in favour of tree-ring growth. It seems that high elevation of habitat provides enough moisture for tree growth but on the other hand occurrence of very low temperature causing failure to provide suitable temperature condition for the start of cambium activities in the first months of growth season. Based on this finding, mean temperature of last century in this region could be reconstructed.