Reconstruction And Analysis Of The Dendroclimatology In The Middle And East Of Altay Region

According to tree-ring samples sites in eight sites of the southern slope of the middle and eastern Altai Mountains in Altay region (including Altay, Fuhai, Fuyun and Qinghe), China, the standard tree-ring width chronologies were developed. The results indicated that the Yiheshannan(YHN), Halaeerqisi(HLE), Yekezhuole(YKZ)and Zhuolesayi(ZLS) chronologies contained more climatic information than the others by comparing and analyzing statistical characteristics of tree-ring chronologies in Altay region. Correlation function analysis was applied to investigate the relationship between tree-ring width and climate during the calibrated period (1963-2008). Correlation results between the chronologies and the climatic data from meteorological stations show that monthly mean temperature from June to July (r=0.555, p<0.0001, n=52), precipitation from January to February (r=0.567, p<0.0001, n=43) and precipitation days from January to February (r=0.550, p<0.0001, n=50) is significantly positively correlated with ring-width indices at the 95% confidence level. Therefore we reconstructed 394 years monthly mean temperature (from June to July), 189 years precipitation (from January to February) and 189 years precipitation days (from January to February) using the chronologies. After demonstrating, the reconstructions were reliable. By analyzing the temperature, precipitation and precipitation days, we find that:⑴The growth of Larix sibirica Ledeb. in the middle and eastern in Altay region is intensively limited by the temperature(from June to July) and precipitation(from January to February). The result has distinct physiological significance. It was verified that the reconstructions were reliable.⑵There were seven warm periods above the mean and seven cold periods below the mean in the 394 years. The maximum temperature period occurred from 1666 to 1691, which was 1.6% more than the mean of the measured data. The minimum temperature period occurred from 1631 to 1665, which was 1.6% less than the mean of the measured data. The longest warm period occurred from 1806 to 1853(lasting 48 years), and the longest cold period occurred from 1854 to 1899 (lasting 46 years).There were five drought periods bellow the mean and five wet periods above the mean in the 189 years. The minimum drought period occurred from 1867 to 1900, which was 22.6% less than the mean of the measured data; the maximum wet period occurred from 1989 to 2002, which was 24.0% more than the mean of the measured data. The longest drought period occurred from 1867 to 1900(lasting 34 years), and the longest wet period occurred from 1901 to 1941(lasting 41 years).⑶In the 189 years , the number of wet years is more than the drought years. The minimum precipitation year occurred in 1885, which was 74.3% less than the long-term mean. The maximum precipitation year occurred in 1914, which was 92.1% more than the long-term mean.According to the mean temperature in the 394 years, we can find that: the maximum temperature was 20.5℃occurred in 1683, which was 2.2℃higher than the mean. The minimum temperature was 16.0℃occurred in 1784, which was 2.4℃less than the mean.⑷The temperature reconstruction has 10 abrupt changes in 1669, 1691, 1714, 1732, 1762, 1781, 1802, 1919, 1939 and 1963. Abrupt changes from high to low occurred in 1691, 1732, 1781, 1919 and 1963, and abrupt changes from low to high occurred in 1669, 1714, 1762, 1802 and 1939.The precipitation reconstruction has 4 abrupt changes in 1847, 1901, 1930 and 1986. Abrupt changes from more to less occurred in 1847 and 1930, and abrupt changes from less to more occurred in 1901 and 1986.The precipitation days reconstruction has 4 abrupt change in 1836, 1902, 1963 and 1986. Abrupt changes from more to less occurred in 1836 and 1963, and abrupt changes from less to more occurred in 1902 and 1986.The power spectrum analysis shows that there are 2.4, 3.3-3.4 and 63 years cycles in the long-term precipitation reconstruction; and there were 2.7-3.7, 43.7 and 52.4 years cycles in the long-term temperature reconstruction.