The Investigation Of The Response Of Tree Radial Growth To Climate Change In Daiyun Mountain

Daiyun Mountain located in the Southeast Coastal of China,which is the mainly distribution of Masson Pine and Tsuga Longibracteata.They are the main afforestation species and the threatened tree species of the world respectively.The warming temperature,uniform distribution precipitation leaded the forest soil drying in recent decades,which influenced tree growth in this area severely.And also,the increasing CO2 changed the intrinsic water use efficiency and growth of trees,and would change the community structure.So it is important to analysis the influence of climate change and the increasing CO2 to Masson Pine and Tsuga Longibracteata,which could provide helpfiul advice for forestry management and saving endangered tree species.Four tree-ring sample sites were choosed in Daiyun Mountain and Gu Mountain,including three tree species.Finally five standared tree-ring width chronologies(STD)and two carbon isotope discrimination(?13C)chronologies were builted.The STD chronologies of Massion Pine include Gu Mountain(GS,1804-2013),Niumulin(NML,1832-2014),Baisongcun(BSC,1873-2014).The STD chronology of Tsuga Longibracteata and Cinnamomum cassia were labealed as TS(1777-2014)and K(1916-2014)respentively.The two tree species growth in the same tree community.The.'A13C chronology include GS(1821-2013)and TS(1777-2014).The chronologies were comparative analyzed combining the existing STD and A13C chronologies of Fangguangyan(FGY),and the ?13C chronology of NML.Tree growth and climate response relationship were analyzed for all the chronologies by the methods of direct and the first-order correlation analysis.The results of growth-climate response analysis of Masson Pine showed the relationships between tree-ring chronologies and pentad climate were more significant than the relationships between tree-ring chronologies and month climate,and the response time were more refinement.The climate of single pentad had an important:implication ojn tree growth.Trees in GS were sincerely limited by the high precipitation in 26th(5.6-5.10)and 49th(8.29-9.2)pentad,and high temperature in 36th(6.25-6.29)pentad.Trees in FGY were sincerely limited by high temperature in 36th pentad(6.25-6.29).Trees in BSC were sincerely limited by the high temperature in 211th pentad(4.11-4.15).Trees in NML were sincerely limited by the low temperature and high humidity in 25th pentad(5.1-5.5).Generally,the Masson Pine of GS,FGY,and BSC showed drought limited,and the response time are different.Trees of NML are limited by the low temperature and the high humidity.The warming climate is helpful for tree growth.The climate of consecutive pentads had an important implication on tree carbon isotope fractionation according the response analysis between tree ring ?13C chronologies and climate.But the response time were different among the three tree-ring sites.Tree ring ?13C in GS was severity promoted by high temperature in 16th(3.17-3.21)pentad,high precipitation in 25th(5.1-5.5)pentad,high humidity in 56-57th(10.3-10.12)and 62th(11.2-11.6)pentad,and limited by long sunshine hours in 43th(7.30-8.3)pentad.Tree ring?13C in FGY was severely limited by the long sunshine hours in 41th(7.20-7.24)and 56-57th(10.3-10.12)pentads,and promoted by the high humidity in 55-59th(9.28-10.22)pentad.Tree ring ?33C in NML was obviously promoted by the high precipitation in 41th pentad(7.20-7.24).The ?13C chronologies of GS,FGY,NML were all limited by the low humidity and long sunshine hours in summer and autumn.The low air humidity usually reduced the stomata conductance and prevented the CO2 enter through the stoma.And the strong sunshine could promote the photosynthesis and reduced the intercellular CO2?so the ?13C of tree ring decline.Under the background of the air CO2 increasing the intrinsic water-use efficiency(iWUE)of Masson Pine increased significantly.And the climte drying in recent decades reduced the stomata conduction,and the intrinsic water-use efficiency(iWUE)of Masson Pine increased further more.The iWUE of GS,FGY and NML showed an obvious increase since 1960s,but iWUE of GS declined in 2000s.Drought limited in GS and FGY are obviouly and the increasing iWUE didn't offset the drought limit.Trees of GS are the eldest among the Masson Pine sites.So the ability of drought resistance were weak than the other Masson Pine sites.And the tree ring widths in GS declined and some trees are going to die.The warming and drying climate and increasing CO2 is helpful for tree growth in NML for the cold and wet environment.The relationships between tree-ring chronologies and pentad climate were more significant than the relationships with monthly climate,and the response time were more accurate.Single pentad climate had an important influence on trees of Tsuga longibracteata,that the extremely high temperature in 20th(4.6-4.10)pentad largely promoted tree growth.But the frees of Cinnamon growing in the same community are limited by the concessive pentad climate.Low temperature from 54th-59th pentad(9.23-10.22),and the long sunshine hours in 23th-125th pentad(4.21-5.5)limited Cinnamon tree growth.?13C of Tsuga longibracteata were limited by the low air humidity and long sunshine hours in 41th-47th pentad.The low air humidity usually reduced the stomata conductance and prevented the CO2 enter through the stoma.And the strong sunshine could promote the photosynthesis and reduced the intercellular CO2,so the ?13C of tree ring decline.iWUE of Tsuga longibracteata were calculated by ?13C,which showed an.increasing trend mainly caused by the increasing CO2.Since 1960s the iWUE showed dramatically rising trend for the increasing temperature,which promoted tree growth of Tsuga longibracteata.so,the warming climate and increasing iWUE would promote Tsuga longibracteata tree growth.