Temperature Variability since 1776 Inferred from Tree-rings of Pinus tabulaeformis in Mt. Helan
油松树轮记录的1776年以来贺兰山地区气温变化

Tree-ring standardized chronologies are developed with 78 cores obtained from eastern and western Mt.Helan.Both STD and RES chronologies correlate negatively with the different periods of early half year temperature,especially January to July(August)(JJ/JA) temperature.It has evident physiological meaning that wide rings were formed when JJ(JA) temperature was low and narrow rings were formed when JJ(JA) temperature was high.Based on this analysis,we reconstructed mean temperature from January to August in the period 1776-1999,and the explained variance is 43.3%(F = 21.422,p < 0.001).The comparatively high temperature periods in reconstruction are 1805-1818,1828-1857,1899-1907,1919-1931,and 1968-1995;and the comparatively low temperature periods are 1858-1872,1883-1895,and 1935-1953.Ten year moving average curve presents three slow uplifting periods of 1766-1853,1862-1931,and 1944-1995.Each temperature increase was followed by a sudden temperature decrease of about ten years,that is to say,the JA temperature has the character of slow increase and sudden decrease.The 70-and 10.77-year periodicities detected in the tree-ring growth series correspond respectively to the Gleissberg(80a) and Schwabe(11a) periodicity of solar activity,and the 2.11-2.62 year cycles are considered to be influenced by QBO(Quasi-Biennial-Oscillation) and the local environmental change.