By using the method of dendrochronology,a tree-ring width chronology from 1840 to 2010 has been built based on the data of Abies ziyuanensis tree-ring in Yanling county of Hunan province.The calculation results show that the data of the standardization(STD) chronology are significantly correlated with the mean air temperature from May to July in 2010.The mean temperatures of May to July at the sampling site were reconstructed by using the regression method.The reconstructed results indicate that four cold periods(1840~1866,1879~1902,1914~...