RELATIONSHIP BETWEEN RADIAL GROWTH OF EARLYWOOD,LATEWOOD OF CRYPTOMERIA FORTUNE WITH TEMPERATURE AND PRECIPITATION CHANGE IN SOUTHWEST SICHUAN PROVINCE,CHINA
Tree-ring width has been widely used to investigate relationships between wood formation and environmental factors,but this proxy can be associated with high autocorrelation and it represents the integrated response to many environmental factors,which may interfere with the climatic signal.Climategrowth interactions have been mostly investigated by correlation/response analysis between ring width and climatic factors.The tree-ring width chronologies of Cryptomeria fortune of 71tree cores in Wawushan Nature Reserve in the southwest Sichuan Province,according to international tree-rings database standard,were developed to investigate relationships between radial growth of earlywood,latewood and temperature,precipitation.The results showed that earlywood width was more sensitive to climate than latewood width,which was insignificant with temperature.And earlywood radial growth was significantly positively correlated with average temperature of April,average maximum temperature in April,maximum temperature of September and October of the last year(rho=0.352,p<0.05;rho=0.297,p<0.05;rho=0.298,p<0.05;rho=0.309,p<0.05),and negatively correlated with mean temperature in July and the minimum temperature in November of the last year(rho=-0.356,p<0.05;rho=-0.293,p<0.05).Radial growth of latewood and mean maximum temperature in October presented significantly positive correlation (rho=0.296,p<0.05).However,radial growth of earlywood and latewood did not have significant correlation with precipitation.Radial growth of earlywood was particularly influenced onlag effect especially from September to October in the last year;monthly mean temperatures in April,October promote the accumulation of nutrients in plants,which is conducive to the formation of earlywood wide rings.Since lower temperature in early spring,early summer,and superabundant precipitation in growing season(especially in June and July),earlywood was easy to form narrow rings.Change of the highest temperature on growing season affected its wide ring formed.The results revealed that changes of different seasonal temperature and precipitation were acted on tree-ring formation and radial growth of early wood and late wood,and precipitation is not a major limiting factor to radial growth of Cryptomeria fortune. Overall tree ring chronology of earlywood and latewood can reflect regional climate change to some extent.