Response Of Stable Carbon Isotope In Chinese Fir Tree Ring Of Different Provenances To Climate Change

The species selection of afforestation tree species has become an important approach for mankind to cope with climate.There are few studies on the response of different tree species indicators of major afforestation tree species to climate change and evaluation of future climate change effects on tree species growth.This article uses the tree-ring stable carbon isotope index for related research.Firstly,statistical characteristics of tree-ring and ?-cellulose in three kind of Cunninghamia lanceolata provenances and their correlation with climatic factors in the planting areas were used to select components that are sensitive to climate change.After that,the ?-cellulose of 30 different geographical provenances were extracted and the ?¹³C value was measured.The average temperature,precipitation,average relative humidity,minimum temperature,and maximum temperature of different provenances and their source areas and planting areas were analyzed.The minimum relative humidity,the year of sunshine hours,the year before the year,the year,quarter,and the monthly value of the year before the current year,and the climatic factors such as the annual minimum relative humidity with strong correlation are gradually returned and filtered out.The dominant climatic factors affecting the stable carbon isotope of the tree-rotor of Chinese fir.Afterwards,a response function was established for these dominant climatic factors.Then,stable carbon isotopes of Chinese fir in different provenances and provenances area with different temperatures from 0.5to0.8°C in the future are predicted to provide theoretical basis for the selection of provenances and provenances area of Chinese fir plantation under climate change conditions.The main conclusions are:?1?A comparative analysis of the responses of ?¹³C in the wholewood and ?-cellulose of Chinese fir to the climate change.We found that the carbon isotope in ?-cellulose was more sensitive to the climate.?2?According to the chronological analysis of ?¹³C valuesin tree rings of 30 kinds of provenance,it was found that the amplitude of ?¹³C values was-23.67‰ to-24.25‰.The autocorrelation coefficient was larger.The corresponding existence of a clear "hysteresis effect."?3?The response of ?¹³C in ?-cellulose in different provenance tree rings to different scale climatic factors is different.For most provenances,it is mainly affected by the minimum relative humidity in the current year,the spring precipitation and the minimum relative humidity in that year,At that time,the summer minimum temperature,the minimum temperature in the previous year and July of the same year,the lowest temperature and relative humidity in August of the same year,and the maximum temperature of years last month,the average temperature in July that year.The different provenance areas were mainly affected by the minimum relative humidity of the year,the summer precipitation and minimum temperature in the year,and the previous year and the year and the minimum temperature.?4?Establish the spring rainfall and minimum relative humidity in the spring of the year by establishing ?¹³C values of different provenance fir tree rounds and the minimum relative humidity of the current year and the minimum temperature in the summer of the current year.The minimum temperature in the previous year and July of the current year was August.The minimum temperature and the average relative humidity,the two-factor response function of the maximum temperature of the previous year and the average temperature of July of the same year,we found that the average contribution rate of the minimum temperature of the previous year and the current year of July to the ?¹³C of the fir trees of different provenances reached 50.57.%.The minimum interpretation amount is 23.88%,and the fitting accuracy is high,which can better represent the changes of the ?¹³C values of the tree rings.?5?Through the ?¹³C values of fir tree wheels in different provenances and the minimum relative humidity of the current year and the single factor response function,the two-factor response function of summer precipitation and minimum temperature in summer and the minimum temperature in June and July of that year was established.The average contribution rate of precipitation and minimum temperature to the ?¹³C of fir trees in different provenances is the highest,the average contribution rate is 68.03%,and the lowest contribution rate is 59.09%.The fitting accuracy of this model is better.Therefore,it can be used as a predictor of the response of the growth of tree rings under different climate conditions in the future.?6?A model with a good fitting effect was used to predict the stable carbon isotope content of the tree rings under the scenario of the increase of the future minimum temperature of 0.5-0.8°C.We found that with the increase of temperature,the carbon isotope values of different provenances and provenance areas showed an upward trend.Thirty provenances responded to future climate changes with different sensitivity patterns of high,medium and low.The Qinba mountain provenance area in the northern subtropics responded more sensitively than other provenances.