Effects Of Age And Competition On Climate Response Of Pinus Koraiensis Tree Rings

The growth of trees is restricted by many factors,including their own physiological factors and external environmental factors.Among them,the age and competition of trees have a vital impact on the growth of trees.This paper takes Xiao Hinggan mountains Pinus koraiensis as the research object,establishes the tree ring chronology of Pinus koraiensis using tree ring climatology method,analyses the rule of radial growth of Pinus koraiensis and the characteristics of climate change in the study area,as well as the response of Pinus koraiensis to climate change,and then studies the influence of age and competition on the climate response of Pinus koraiensis tree ring by correlation analysis,revealing the age and competition.The response mechanism of Pinus koraiensis growth and climate factors provides scientific basis for the management and cultivation of Pinus koraiensis forest under climate change.The results show that:(1)The growth of Pinus koraiensis fluctuated with time series.Before 1974,the growth variability of Pinus koraiensis was great,and then the growth became stable.The temperature in the study area increased significantly from 1956 to 2016(p<0.01),and the precipitation did not change significantly.The lowest temperature(0.53 C/10a)rises fastest and the highest temperature(0.36 C/10a)rises slowest.The precipitation in March(2.078 mm/10a)and May(4.984 mn/10a)increased significantly,but the overall change trend of precipitation was not significant.The standard chronology of Pinus koraiensis is of high quality.The climatological analysis of tree ring rings shows that the radial growth of Pinus koraiensis is negatively correlated with the average temperature and the highest temperature in June,positively correlated with the precipitation in June,and the relationship between the minimum temperature and the radial growth of Pinus koraiensis is scatteredineachmonth.(2)Competition will increase the sensitivity of Pinus koraiensis radial growth to rainfall in June.Competition has no effect on the relationship between Pinus koraiensis radial growth and temperature factors.The relationship between radial growth of small-diameter Pinus koraiensis and precipitation in June is the most sensitive to competition,followed by medium-diameter Pinus koraiensis,and the relationship between radial growth of large-diameter Pinus koraiensis and precipitation in June is not sensitive to competition.Competition will strengthen the correlation between growth and precipitation in June,and weaken the correlation between growth and average temperature in June.Competition has the most obvious effect on the correlation between radial growth and precipitation in young Korean pine,while competition has little effect on the correlation between radial growth and temperature and precipitation in older Korean pine.The effect of competition on the growth of Korean pine is mainly on small-diameter and small-age Korean pine.Appropriate regulation of stand density is more conducive to the growth of small-diameter Korean pine,especially in dry years.(3)The competition pressure of Korean pine in the study area is negatively correlated with DBH and tree height of Korean pine.The competition pressure of Korean pine with large diameter and high tree height is smaller,while that of Korean pine with small diameter and low tree height is generally larger.Under different competition pressure conditions,the trend of annual ring width index of Korean pine is different.The annual ring width index of Pinus koraiensis varying with different tree ages showed a steady increasing tr-end,but the increasing trend was not significant.The quality of standard chronology of Pinus koraiensis at the same age is better than that of the difference chronology.The tree ring chronology of Pinus koraiensis at different age is different from that of climate response.The chronological analysis shows that the growth of young Pinus koraiensis is greatly influenced by the climate of the previous year,and older Pinus koraiensis contains more climate informatin.