The Responses Of Radial Growth Of Cunninghamia Lanceolata From Different Provenances To Climate Change

Cunninghamia lanceolata is the largest fast-growing tree species in plantation area in China,and also one of the most important commercial tree species in China.The great span of distribution area of Chinese fir makes its growth have obvious geographical differences,and forms the ecological types of provenances adapted to different regions.The higher ratio of height to diameter of Chinese fir makes it also more vulnerable to extreme climate damage.In recent years,with the aggravation of climate change,the impact of climate change on the yield and quality of Chinese fir plantation is becoming increasingly serious.Many scholars on different provenances have made Chinese fir growth and physiological characteristics of a large number of studies.However,there are relatively few studies on the response of chronological series of Chinese fir from different provenances to climate change,therefore,it’s an urgent task to reveal the response mechanism of t he radial growth of different provenances to climate change and to improve the stress resistance of Chinese fir plantation.Based on the tree-ring climate correlation analysis method and the tree-ring data of 60-year-old Chinese fir provenances in central Sanming of Fujian Province,this study established the tree-ring residual chronology(RES)of Chinese fir,and the relationship between the radial growth and the wood density of Chinese fir(whole-ring width,early-wood width,late-wood width,full-ring density,early-wood density,late-wood density,maximum-wood density and minimum-wood density)and the main climatic factors(temperature,precipitation,humidity)was analyzed,what’s more the effects of di fferent climatic factors on t he radial growth and wood density of Chinese fir from different provenances and the stress resistance of Chinese fir from different provenances were studied.The main findings are as follows:(1)The responses of annual ring radial growth of Chinese fir from different provenances to climate change were different.The tree-ring width and early-wood width of Chinese fir in general provenances were positively correlated with precipitation and relative humidity in autumn(p<0.05),and late-wood width was positively correlated with precipitation in spring and relative humidity in summer.The tree-ring width of Chinese fir in better provenances was negatively correlated with summer temperature,and the early-wood width was positively correlated with autumn relative humidity.There is similarity between the response of the tree-ring width and the early-wood width to climatic factors.(2)The response stability of annual ring radial growth of Chinese fir from different provenances to climatic factors was different.The late-wood width of Chinese fir in general provenances was positively correlated with summer precipitation and maximum temperature in March of the current year,and this kind of relationship becoming obvious year by year.The early-wood width of Chinese fir in better provenances was negatively correlated with the June temperature of the current year,and this kind of relationship becoming unapparent year by year.From the stability,the relative humidity in October of that year was the main climatic factor limiting the radial growth of Chinese fir.Chinese fir with better provenance is more sensitive and indicative to climate factors.There was a significant "lag effect" in the response of Chinese fir annual ring growth to the climatic factors of the previous year,and a significant "lag effect" in the response of late wood growth to the climatic factors of early Chinese fir growth.(3)The responses of tree ring density to climate change of Chinese fir from different provenances were different.The tree-ring density,early-wood density and minimum density of general provenance Chinese fir were negatively correlated with autumn temperature,while the late-wood density and maximum density were negatively correlated with autumn relative humidity.The tree-ring density of better provenances Chinese fir was significantly positively correlated with the relative humidity in spring,significantly negatively correlated with the precipitation in autumn.The late-wood density and the maximum density were negatively correlated with the precipitation and relative humidity in autumn.The responses of early-wood density and minimum density,late-wood density and maximum density to climatic factors were similar.The response of annual ring density to climate factors in the previous year has a lag effect,and the response of late-wood density to climate factors in the spring of that year also has a lag effect.(4)The response stability of tree ring density to climate factors in different provenances of Chinese fir is different.The tree-ring density and early-wood density of C hinese fir from general provenances were positively correlated with the lowest temperature in October of the previous year,while the late-wood density of Chinese fir from better provenances was negatively correlated with the precipitation and the minimum relative humidity in autumn of t he current year,and the stability is strongest,achieves the remarkable correlation in the entire time scope.Under the background of global warming,the maximum density of Chinese fir in general provenances was positively correlated with the average temperature and precipitation in June of the current year,and this kind of relationship become gradually obvious,while there was a negative correlation between the minimum density of Chinese fir in better provenances and the average temperature,minimum temperature,precipitation and average relative humidity in October of t he previous year.(5)When Chinese fir copes with extreme environmental events,the drier the climate is,the weaker its resistance will be,and the stronger its resilience and elasticity will be;the wetter the climate is,the stronger its resistance will be,and the weaker its resilience and elasticity will be.When Chinese fir was exposed to extreme drought events,the resistance of the better provenances was stronger than that of the general provenances,but their resilience and elasticity were weaker than that of the general provenances,and the elastic force of Chinese fir from better provenances was stronger than that from general provenances.(6)Chinese fir in better provenances was more susceptible to monsoon impact than the general provenances.Chinese fir from the general provenances was significantly correlated with Indian monsoon.While from the better provenances was significantly correlated with southeast monsoon.Westerly and northerly winds also have significant effects on the growth of Chinese fir from better and general provenances.