Response Of Radial Growth Of Three Dominant Tree Species To Climate In The South Part Of Daxing'an Mountains

Under the influence of high temperature and drought in the southern part of Daxinganling Mountains,Larix gmelinii,the natural forest of the top community,was destroyed,and formed a secondary poplar forest.In addition,in order to restore the ecological construction,the artificial forest Larix principis was planted.To explore the different response characteristics of different tree types to climate change,by analyzing the change trend of different trees in the same area,we get more comprehensive and specific understanding of the response of vegetation to climate.We take Saihanwula in the south section of Daxinganling Mountains as the research area,respectively collect Larix gmelinii,Populus davidiana and Larix principis as the research objects,and use the tree ring climatology method to establish tree ring width chronology,then use correlation function to analyze the correlation between meteorological factors and chronology in 1953-2018,to reveal the response of tree radial growth to climate:1.The correlation between the radial growth and meteorological factors:the radial growth of Populus davidiana in the natural forest is significantly negatively correlated with the average temperature in June and August of the previous year and June of the year(P<0.05),and there is a significant negative correlation with the average temperature in September of the previous year(P<0.01),the main limiting factor is temperature;the radial growth of Larix gmelinii is negatively correlated with the precipitation in June of that year(P<0.01),the main limiting factor is precipitation;the radial growth of Larix principis is negatively correlated with the average maximum temperature and average temperature in May and July of the previous year(P<0.05),and it has a significant positive correlation with the precipitation in November of that year(P<0.01).It is also positively correlated with other months,but not significant.The results show that Larix principis is mainly affected by precipitation in winter.2.The change of tree growth in extreme climate:the response of trees to climate has lag effect,the response of Larix gmelinii and Larix principis to climate has obvious "lag".Larix gmelinii and Larix principis is suitable for the growth in arid areas.The effect of drought stress on the radial growth of trees in the current year is not significant,and the effect on the radial growth of trees in the next 2-3 years is significant.Populus davidiana is usually affected by the climate in that year or the second year.Populus davidiana has high sensitivity to climate response,and low internal drought resistance mechanism and stability.The annual soil water use efficiency of three kinds of trees is calculated,and the results show that the soil water use efficiency of Larix principis is the highest.And Larix principis is a fast-growing tree species,which has a high efficiency of soil water use.The main limiting factors of radial growth of Populus davidiana,Larix gmelinii and Larix principis in natural forest are temperature,precipitation and precipitation in November of that year.The response of Larix gmelinii and Larix principis to climate has obvious "lag" and strong drought resistance;Populus davidiana is sensitive to climate response with low drought resistance and stability.The order of soil water use efficiency from high to low is Larix principis,Larix gmelinii and Populus davidiana in natural broad-leaved forest.