Climate-Sensitive Growth And Mortality Model Of Changbai Larch(Larix Olgensis) Forests

Climate change affects the distribution,growth and other processes of forests and poses new challenges to the sustainable management of forests.The traditional empirical stand growth model cannot predict the forest growth under climate change because it does not consider climate factors,so it is necessary to build a climate-sensitive stand growth and harvest model.We established the climate-sensitive diameter growth model,the climate-sensitive recruitment model and the climate-sensitive mortality model of Changbai larch(Larix olgensis)plantation by using the data of continuous inventory of forest resources in Jilin province in 2009 and 2014,as well as the average climate data from 2009 to 2014.On the basis of the matrix model,the diameter grade distribution law of larch path in climatic conditions is analyzed.The conclusions are as follows:(1)Established the climate-sensitive stand diameter recruitment model and the mortality model.Compared with the basic model,the accuracy of the climate-sensitive recruitment model and the mortality model was increased after the addition of climate variables,which indicated that the model was optimized and more accurate with the addition of climate factors.(2)Among the factors that affect the growth and loss of larch,the diameter growth of larch has a positive correlation with diameter at breast height(DBH),and a negative correlation with the sectional area per hectare;the withered loss of larch has a positive correlation with the sectional area and a negative correlation with the DBH.In the climate variables,the total precipitation in the growing season and the average temperature in the hottest month affect the diameter growth of larch;the average temperature in the growing season and the average precipitation in the hottest month affect the withering loss of larch.(3)Established the climate-sensitive recruitment model.The foundation model was well fitted,the stand basal area was negatively correlated with the number of recruitment trees,and the average stand diameter was negatively correlated with the number of recruitment trees.In the climate sensitive model,the fitting effect of climate variables is not significant.It may be due to cutting in the sample site between 2009 and 2014,leading to the factors of each stand change after cutting,making the reduction of competition among trees,and the dependence of forest boundary on environmental factors is disturbed.(4)Established the matrix model.It is found that the probability of upward transfer and the probability of dry loss of larch decrease with the increase of the diameter grade,and the probability of upward transfer and the probability of dead trees approach zero at the large diameter grade.The influence of climate variables on larch’s radial order transfer is realized by changing the transfer probability.Precipitation during the growing season promoted the diameter growth of larch,and also accelerated the diameter grade transfer of larch.The average temperature of the hottest month was the opposite.For the prediction of each diameter step,after 28 diameter steps,the mean relative error(MRE)of the model increases,because the number of larch trees in the large diameter grade is less,which leads to a large deviation.