Research On The Change Of ?¹³C Of Pinus Tabulaeformis On The Southern Of Qinling Mountains And Its Relationship With Climatic Factors

The Qinling Mountains traverse the central part of China,which is a natural north-south geographical boundary line.It is also an importan boundary line between warm temperate zone and subtropical climate zone in China.The northern of the Mountain and the southern of the Qinling Mountains has a significant climate difference.Climate change there is very sensitive at different altitudes.Based on the principle of dendroclimatology,we collected Pinus tabulaeformis Carr.tree ring samples of three altitude?1250 m,1450 m,1650 m?in 2015,after pretreatment,cross dating,determination of carbon stable isotope and other steps,we got the carbon-stable isotope(?¹³C)of tree-rings from 1972 to 2013 at three altitudes,which was analyzed by SPSS 19.0 software,with correlation analysis and multiple regression analysis.We get laws through analying the response of?¹³C of Pinus tabulaeformis in the southern slope of Qinling Mountains in Shaanxi Province.The results of the study correctly help us understood and evaluated complex and changeable climate changes of Qinling Mountains.In this paper,the natural growth of Pinus tabulaeformis in the middle part of the Qinling Mountains is studied.The relationship between the tree ring?¹³C and climatic factors is studied,which makes up for the deficiency of the?¹³C study of the tree-ring in the Qinling Mountains.It is a deep revealing of the growth of Pinus tabulaeformis in the climate change background.This paper has the following conclusions:1.In the past 20 years,the climate in Foping County has been changing remarkable.From 1990 to 1995,as a turning point in the climate of Foping County,the climate became a trend of great change.The temperature,precipitation and relative humidity changed from the previous random fluctuations to the upward trend,and significant interdecadal changes occurred.After the increase of precipitation and precipitation,the temperature in Foping area showed a significant warming trend after 1993,and the linear tendency rate of temperature reached 0.72°C/10a.2.Tree ring?¹³C contains abundant climate information.The low altitude?1250 m?Pinus tabulaeformis?¹³C was significantly positively correlated with the temperature of April of the previous year?P<0.05?,and was significantly positively correlated with the precipitation in October of that year?P<0.05?.The medium altitude?1450 m?of Pinus tabulaeformis?¹³C there has a significant positive correlation with temperature in February of that year?P<0.05?,and it also positively correlated with extreme monthly high temperature in May?P<0.05?;Pinus tabulaeformis?¹³C in high altitude?1650 m?was significantly negatively correlated with temperature in October of that year?P<0.05?,and there was a significant positive relationship with air humidity in January?P<0.05?.3.Changes in temperature and precipitation have significantly effects on the growth of Pinus tabulaeformis.In 1978 and 1990,the temperature in summer and winter was low and the temperature in autumn was high.The temperature in July was lower than that in August.The precipitation in April-September was too volatile.These abnormal climate changes disturbed the normal physiological activities of Pinus tabulaeformis and destroyed.The photosynthesis process of Pinus tabulaeformis caused an abnormal decrease in the?¹³C value.4.Multiple regression analysis showed that the carbon stable isotope generation of Pinus tabulaeformis at three altitudes in the Qinling Mountains was affected by various climatic factors,not a single climatic factor,but a polymerization factor.A multivariate regression equation established by extracting the main climatic factors from the carbon-stable isotopes of Pinus tabulaeformis can be used to reconstruct some highly correlated climatic factors.