Response Relationship Between Tree-ring Density And Climatic Factors And Clmate Reconstruction In Gongnaisi Region Of Yili, Xinjiang

The purpose of the article is for first time to study response relationship between tree-ring density and climatic factors and climate reconstruction in Gongnaisi. Some master ring-density dating chronologies was developed by data of spruce. It analyzed character of statistics among the density chronologies indices and response of climatic factors on tree-ring density through correlation method and response surface method. By means of stepwise regression and different detrending methods, seven climatic series was reconstructed by density chronologies of high sensitivity. Analyzing the reconstructed series show that:(1)The character of statistics that tree-ring density change was aroused by increscent elevation in Gongnaisi region was showed: high frequency information of springwood density and tree-ring minimum density was some decrease and synchronism of summerwood density and tree-ring maximum density was increase when elevation increase. It is best from western and middle of Tianshan mountain in upper forest limit that analysis representation of tree-ring density in circumjacent area.(2)Springwood, summerwood density of the lower forest limit and summerwood density of the upper has regularity to response of climatic change, but springwood density of the upper is different. Precipitation from April to August influences growth of springwood density in the lower limit of regional forest. Limitative factor of tree-ring density development in the upper limit is temperature from July to August. It was same result that is distinct correlation between tree-ring maximum density and summer temperature in the international. Correlation coefficient between density of springwood and minimum and PDSI in the lower limit is better than in the upper and middle region of the forest. it of between density of summer and maximum and PDSI in middle region of forest is more value than in upper and lower and its absolute value increase when late mouth come.(3) Tree-ring density chronologies were developed by different t detrending methods like as smoothing spline function of 60 to 180 step size, regional curve(RCS) and general negative exponential curve. Some high sensitivity density chronologies was selected through correlation coefficients between the chronologies and climatic factor, seven climatic series were reconstructed by the chronologies. The series include average temperature and precipitation of Tianshan mountains snowcover and avalanche station, average temperature, maximum air temperature, minimum air temperature and precipitation of Xinyuan station, and Palmer Drought Severity index of the region from April to August. It is widely validated that the reconstructed series is credible by means of leave-one-out and bootstrap methods. But high frequency information of average temperature, minimum air temperature and precipitation series of Xinyuan station had some loss. Space representative of average temperature and maximum airtemperature of Xinyuan station is best among this series. (4)In 1835-2005, the coldest phase were 1835-1839 and 1950-1959 years, the warmest phase was 1870-1879, the drought phase was 1860-1869 and the wet phase 1840-1849 in Gongnaisi region. Clammy phase at the end of qing dynasty is same exist in central regions and western of Tianshan mountain. The reconstructed long-term temperature series sequence had 3,6,14-15,56-57 and 84-91a changing periods. The series had abrupt change in 1858-1859,1881-1886,1944-1948 and 1975. The reconstructed precipitation and PDSI series had 3,4,6,7 and 43-59a changing periods and had abrupt change in 1856-1857,1884-1885 and 1984-1985 years. The short cycle meanwhile appeared because driving factors of the periods influence temperature and precipitation of the regions at the same time, but the influence impact strength is different at different phase.