Different Responses Of Radial Growth Pinus Tubuliformis To Climate Change At The Southern And Northern Slopes Of Qinling Mountains

Pinus tabuliformis samples were collected from the southern and northern slopes of the Qinling Mountains to establish their standard chronology(STD).The correlation between radial of P.tabuliformis and climatic factors were explored using Dendroclim2002 software.An optimal regression relationship model of the radial growth of tree with climatic factors was developed,and the driving factors for the formations of extremely wide and narrow treering on different slopes were explored.This was important for analysing the differences in the radial growth of trees on the southern and northern slopes of the Qinling Mountains in responses to climate change,as well as providing data to support the construction and protection of the ecological environment in the Qinling Mountains.The results indicated that.(1)During the period 1959—2017,there were highly significant differences in precipitation and relative humidity between the southern and northern slopes of the Qinling Mountains.There were significant differences in mean temperature,and no significant differences in maximum temperature and minimum temperature.The variability in climatic factors caused the radial growth of P.tabuliformis on the northern slopes to be more sensitive to climate change than on the southern slopes of the Qinling Mountains,which were more suitable for the radial growth of P.tabuliformis.(2)On the northern slopes of the Qinling Mountains,the radial growth of P.tabuliformis was positively correlated with moisture factors in previous September and current May.The radial growth of P.tabuliformis was positively correlated with temperature factors in previous November and negatively with previous October and current May.On the southern slopes of the Qinling Mountains,the radial growth of P.tabuliformis was positively correlated with moisture factors and temperature factors.The radial growth of P.tabuliformis was positively correlated with moisture factors from previous September to current February,current June and August.The radial growth of P.tabuliformis was positively correlated with maximum temperature from previous September to current July and current September.The radial growth of P.tabuliformis was positively correlated with mean temperature and minimum temperature in previous September,from previous November to current April,from current June to July and September.The radial growth of P.tabuliformis was well correlated with the PDSI drought index,and positive correlations were identified from September to December of the previous year and in May of the current year on the northern slopes of the Qinling Mountains.The radial growth of P.tabuliformis was well correlated with the maximum temperature,and positive correlations were identified from March to April of the current year.The lag effect of climatic factors on the radial growth of P.tabuliformis was significant on the southern and northern slopes of the Qinling Mountains.(3)The optimal regression relationship model was able to simulate the relationship between STD and PDSI.On the northern slopes of the Qinling Mountains,the formations of extremely wide and narrow tree-ring were mainly the result of drought condition.Combined with climatic indicators,PDSI could better reflect the radial growth characteristics of P.tabuliformis.On the southern slopes of the Qinling Mountains,the formations of extremely wide and narrow tree-ring were mainly the result of maximum temperature,and the formations of extremely wide and narrow tree-ring also required consideration of the effect of relative humidity.