Response Of The Tree Ring Width Of Pinus Tabulaeformis In The Qinling Mountains To Climate Change

Qinling is the east-west direction of the mountains and the watershed between the Yellow River and the Yangtze River,the middle of which are located in the territory of Shaanxi.The Qinling mountains-Huaihe River is an important geographical north-south demarcation line,800 mm isohyet and January 0 ?isotherm,so it is a sensitive area of climate change and important for the study of climate change in the region.August 2015 in Foping National Nature Reserve at altitudes of 1250 m,1450 m,and 1650 m,we collected 120 sample cores of pinus tabulaeformis,after fixed,natural air drying,grinding and other experimental treatments,using WinDENDRO analysis software to measure ring width,early wood width and late wood width.The crossdating result of tree ring width data was tested with COFECHA software,then the growth trend of pinus tabulaeformis ring width was determined by ARSTAN software after cross dating with the spline function,the standardized chronologies of pinus tabulaeformis at three different altitudes was obtained.Using the DENDROCLIM 2002 software,by correlation analysis,to analysis the relationship between the standardization chronologies of three different altitudes and monthly average temperature and monthly precipitation.Finally,we use multiple linear regression method to establish the response function equation between tree ring width and climatic factors.The study concludes that the average sensitivity of pinus tabulaeformis of low altitude tree ring width,early wood width and late wood width is higher than that of middle and high altitude samples of pinus tabulaeformis,the result shows that there are more climatic information of pinus tabulaeformis at low altitude than that in middle and high altitude areas.On the whole,the tree ring width of pinus tabulaeformis is positively related to temperature and negatively correlated to precipitation,there are different correlations in the different growth periods of pinus tabulaeformis at different altitudes,there are small correlation between the width of ring,early wood,late wood and the precipitation the correlation coefficients are all below-0.3.The pinus tabulaeformis ring width of altitude 1250 m has the best correlation with monthly average temperature and the maximum correlation coefficients of the monthly average temperature of the year March,June and July,which are all greater than 0.6.In this study,the annual ring width index of this year of pinus tabulaeformis is the dependent variable,the annual ring width index of last year and the monthly average temperature in the year of March,June and July are the independent variables,the response function of the ring width and monthly temperature of pinus tabulaeformis is established by the multiple linear regression method with the origin software.According to the response function,it can be concluded that if the temperature rises by 1?,the annual ring width index of pinus tabulaeformis will increase by 0.75.