Nanjing Purple Mountain Masson Pine Tree-ring Stable Carbon Isotope Environmental Significance

It is important to reflect and analyze the environment by distilling the information of tree ring stable carbon isotope. We analyze the response of the two δ¹³C annual series of Pinus massoniana Lamb in Nanjing Chongshan to the growing environment including aspect, climatic factor, incident of disaster, sunspot and ENSO etc. Moreover, we research the reflecting mechanism and extent of these environment factor to tree ring δ¹³C, consequently offer good basis for utilizing tree ring reconstructing variation of environment. Besides, we prove the feasibility of reconstructing the environment factor with tree δ¹³C through giving an example..We draw a conclusion that aspect position of tree ring can result in the difference of tree ring δ¹³C and tree ring response to environment factor such as wind speed. Through analyzing the correlation between tree ring δ¹³C of Pinus massoniana Lamb and climatic factor of Nanjing, we discover that there has positive correlation between δ¹³C and monthly mean temperature and monthly maximum temperature and time of sunlight in growing period(esp. summer and fall), as well as negative correlation between δ¹³C and monthly mean minimum temperature, precipitation, relative humidity of atmosphere and mean wind speed. The correlation between δ¹³C and relative humidity of atmosphere, precipitation, time of sunlight and monthly maximum temperature is rather apparent than the others. We think that it is close correlation to the growing character of Pinus massoniana Lamb and the typical subtropical climate in Nanjing.The tree ring series can record the incident of natural disasters well. Almost it is revealed by the corresponding relation between the δ¹³C series and the disasters that the δ¹³C is maximum corresponding to dry period and minimum to wet period. The three years with strong cold wave( 1954a, 1969a and 1977a) are corresponding to the two δ¹³C series, those above offer evidence for reconstructing the regional or even the global incidence of disaster outstandingly.Analysis of power spectrum indicates that the tree ring δ¹³C reflects the active cycle of sunspot around 11 years, impact to the growth of tree by sunspot lags about 5 years. There has an apparent negative correlation between the periodical variation of sunspot activity and the periodical fluctuation of tree ring δ¹³C. Moreover, analysis of cycle shows that both of the two tree ring δ¹³C series have recorded the cycle of ENSO about 2-4 years. There has a correlation between the tree ring δ¹³C and ENSO: the δ¹³C is increasing when it is ENSO warm incident and decreasing when cold incident.Through multiple regression analysis it illustrates that main factor of δ¹³C annual series of Pinus massoniana Lamb is the period of grow especially the relative humidity of atmosphere and the precipitation in summer and autumn; the secondary factor is the sunspot. Furthermore, it demonstrates that there has difference in factors between the two series due to the different growing environment.