The Response Of Radial Growth To Climate Change And Forest Fire Of Larix Gmelinii

Fire disturbance is one of the most widespread disturbances in forests.Daxing’anling Mountains is the largest primitive forest area in China,where fires occur frequently.However,there are few reports on the effects of fires on tree radial growth and climate response in this area.From the perspective of tree ring,this paper studies the response of radial growth and climate of Larix gmelinii post fire in Mohe,aiming to reveal the ecological mechanism of fire disturbance on forest ecosystem,and provide scientific basis for predicting the recovery of trees after fire.The ring cores were collected from mild burned,moderate burned,severe burned and unburned plots.And we established the ring width chronology,earlywood width chronology and latewood width chronology.The change of ring width,the proportion of earlywood and latewood,the correlation between the radial growth and climatic factors under different fire intensity was analyzed.The main results are as follows:(1)Different fire intensities effact the radial growth in different way.The growth of Larix gmelinii was accelerated in the mild and moderate burned plots,but decelerated in the severe burned plots.(2)The ratio of early and late wood in three fire intensity plots was similar to that of the control plot,and the median value fluctuated around 2.The width ratio of early and late wood after low intensity fire was slightly higher than that before fire,without significant difference.There was no significant change in the ratio after moderate fire,but the fluctuation range was larger than that before fire.The ratio after high intensity fire was lower,and there was significant difference before and after fire.(3)After mild burning,the tree-ring width was positively correlated with the highest temperature in September,November of the previous year and September of the current year,together with the precipitation in July of the current year and previous year.After moderate burning,the correlation between the ring width and the lowest temperature in August of the previous year is significant negative.And there is a significant positive correlation between the ring width and the highest temperature in December of the previous year.However,after severe burning,the tree-ring width was negatively correlated with the highest temperature in July of the current year and previous year.(4)The change of response between ring width and climatic factors were more obvious after severe burned than mild and moderate burned.Mild burning only affects the relationship between the radial growth and the highest temperature in October and the lowest temperature in July of the previous year.While severe burning could affect the relationship between the radial growth and the precipitation in November of the previous year,January as well as April in current year,and the highest temperature in June and August of current year,significantly.So we can speculate,higher temperature is not help for the recovery of the Larix gmelinii forest after moderate and severe burning.However,it is no obvious response on the radial growth in the mild burned plots.