Correlation Study On Climate Based On Ring Width Chronology Of Ulmus Pumila And Climate Change In Inner Mongolia Duolun County In Past60Years

Tree-ring data has been widely used in the study on climate change in the historical period because of its advantages of dating accuracy, high resolution and strong continuity.To analyze climate trends in nearly60years, the climatic data observed from1953to2012in Duolun County in Inner Mongolia Autonomous Region was analyzed using the methods of the linear trend, moving average and etc in this research. Followed the basic principles of dendrochronology, the ring-width chronology of Ulmus pumila was established. In order to seek the main limiting factors influencing the growth of Ulmus pumila in the locality, the correlation was analyzed between chronology and climatic factors. Using a linear regression method, a model was established between the tree-ring-width chronologies and climatic factors, and main climatic elements in the past164years were rebuild, which enriched the climate proxy data. The main conclusions were drew in this paper as following:(1) Affected by global climate change in the world, temperature was uptrend in fluctuation, and precipitation levels, relative humidity, wind speed and sunshine hours decreased nearly60years in Duolun County. The annual average temperature showed an clear feature of "front warm and behind cold", and tendency rate is0.39℃/10a. The warming is more significant in winter and February, and the extreme minimum temperature and the average minimum temperature warming are more significant than the extreme maximum temperature and average maximum temperature respectively. Rainfall in summer, as a major contributor to the annual precipitation, was in downward trend consistent with annual precipitation trends. The rate of annual tendency of average relative humidity, average wind speed and sunshine hours were-0.82%/10a,-0.11(m/s)/10a,-51.95h/10a respectively. The largest seasons contributed to annual fall were winter, winter and spring.(2) The whole ring width, the standard chronology (STD) of early wood and late wood ring width, residual chronologies (RES) and autoregressive chronology (ARS) of Ulmus pumila were respectively established using the procedure of international databases ARSTAN. It was preliminarily considered that temperature was the main limiting factor affecting the radial growth of Ulmus pumila through the correlation analysis between every chronologies and climatic factors. According to the degree of correlation, the reconstruction equation for minimum temperature in annual average was ultimately established as y=3.214x+3.013x1-10.293. The reconstruction equation of mean minimum temperature was y=3.577x+3.058x1-10.090in autumn:The reconstruction equation of extreme minimum temperature in September was y=8.094x-10.809, and all these equations were verified on the stability and reliability.(3) The analysis on sequence variation of historical reconstruction showed that minimum temperature of annual mean had the same trend with the mean minimum the temperature in autumn in the past164years (from1847to2010) in Duolun County, which had undergone6partial warm and5partial cold phase,6peaks and5valleys, and the peak of wave cycle was from17to54years, and the valley of wave cycle was from17to39years. Extreme minimum temperature in September had undergone5partial warm and5partial cold phases, and6peaks and5valleys. The peak of wave cycle was from21to41years, and the valley of wave cycle was from19to46years.