TREE-RING WIDTH BASED MAY~JUNE MEAN TEMPERATURE RECONSTRUCTION FOR HUASHAN MOUNTAIN SINCE A.D. 1558 AND 20TH CENTURY WARMING
Global wanning was widely accepted in the 20th century,but there were diversities in different regions. This paper analyzed the background of the regional response to global change in the Huashan region of Eastern Qinling Mountains by tree ring. Temperature changes inferred from the proxy data, especially from tree-ring data have been studied on the Northern Hemisphere. In this paper, we provided a tree-ring-width chronology of A. D. 1528 ~ 2006 of Pinus tabulaeformis in Huashan(34°28'N, 110°04'E),the eastern end of Qinling Mountains, which was an important geographic demarcation line in the east of Central China. Correlation analysis showed that the tree-ring-width chronology significantly correlated with the average temperature of May ~ June. Based on this result, we reconstructed the mean May ~ June temperature of A. D. 1558 ~2006 using tree-ring index in the Huashan region. The explained variance reached 41%, and 40% after adjusting degree of freedom. Both "Jackknife" and "Bootstrap" methods were used to estimate the reliability of the regression function. All these statistics based on above two methods were close,which displayed the function was reliable. The reconstruction displayed the fluctuation of temperature in this region. There were 120 years of high temperature,accounted for 26. 7% of the total reconstructed series,and 129 years of low temperature,accounted for 28.7%. The frequency of high temperature year and low temperature year was almost equal over all the reconstructed period. And there were two obvious long warm periods,i. e. ,A. D. 1698 ~1708 and A. D. 1749 ~ 1777. The long-low-temperature period reconstructed occurred from the early 1930s to 1950s of the 20th century, with the lowest temperature of 12. 0℃ occurring in 1933. Since the 1970s, temperature has been increased rapidly, which agreed well with global warming of the late 20th century. The reconstructed temperature of Huashan was significantly correlated with the reconstructed temperature of Nanwutai(r = 0. 49 ,N =246,p < 0. 0001 ). Both can also be well compared with an 11-year moving average(r = 0. 41,N = 236, p < 0. 0001 ). Two curves showed a synchronous warming trend, which proved our result to be reliable. Thus,Pinus tabulaeformis has a great potential for temperature reconstruction in this region.
HuashanPinus tabulaeformistree-ring widthMay ~June mean temperature