Reconstruction And Analysis Of The Past 470 Years' Spring Climate Change In The Urumqi River Source On The Northern Slope Of Tianshan Mountain

Correlation calculation indicates that the tree-ring chronologies significantly positively correlate with spring (April and May) precipitation and temperature of Daxigou Meteorological Station, with the greatest single correlation coefficient of 0.490 and -0.631(Significant is much greater than the 99.9 percent level). Using HXC.STDt and BEQ.STDt+2 standardized tree-ring chronology series, the long-term sequence of spring precipitation was reconstructed, with an explained variance of 41.6%; In the same way, using BCD.RESt and BEQ.RES residual tree-ring chronology series, the long-term sequence of spring temperature was reconstructed, with an explained variance of 46.0%.It is verified that the reconstructed precipitation and temperature were reliable.Analyzing the reconstructed series show that:1) The growth of the alpine timberline spruce in Haxionggou, Bingchuanzhandong and Boerqingou is intensively limited by the spring (Apile and May) precipitation and temperature in the Urumqi River Source on the Northern Slope of Tianshan Mountain.The result has distinct physiological significance. It is widely validated that the reconstructed long-term spring precipitation and temperature is credible.2) In the 467 years, the spring precipitation in the Urumqi River source experienced 13 wet periods and 12 dry periods. And there were 276 normal years,86 dryish years,98 dampish years ,5 dry years and 2 wet years; and the longest dampish periods was 1646-1687 (42 years),the longest dryish periods was 1704-1733 (30 years).The great wettest periods was 1694-1703 (the mean precipitation was 86.9 mm,18.7% higher than that of the recent 41years) ,and the great driest periods was 1635-1645 (the mean precipitation was 60.0 mm, 18.0% lower than that of the recent 41...