Study On The Characteristics And Growth Regularity Of Larix Chinensis Age Stage

Qinling Mountains is the important north-south geographical boundary of China,it is also one of the hottest research areas that firstly began to study Dendroecology in China.Larix chinensis is a rare tree species,which belongs to the rare plant species of secondary protection in China.Based on the data from 7 sampling sites,this study analyzed the relationship between altitude,age and Larix chinensis’ Basal area increment（BAI）,the ARIMA model was used to simulate the growth of the BAI sequence of Larix chinensis,and the law of the growth variation was analyzed.The study of the relationship between the altitude and the BAI showed that Larix chinensis’ BAI of the lower altitude in the southern slope had better growth trend.The BAI growth curve showed a more steady growth trend as a whole.There is a significant positive correlation between altitude and the BAI.The growth trend of Larix chinensis’ BAI at the middle altitude was faster,and the fluctuation was larger.There’s a comparatively significant positive correlation between the altitude and the total increase of the BAI,and a weak positive correlation between the altitude and the average BAI.Larix chinensis’ BAI of the upper altitude grew slowly.There’s a significant negative correlation between the altitude and the growth,which proved that the altitude was one of the important limiting factors affecting the growth of Larix chinensis at the upper altitude area.The study of the relationship between the age and the BAI showed that the BAI growth of grade III was the fastest in young age.The correlation analysis showed that the correlation between the BAI of the two groups was 0.976^**、0.906^**.There’s a significant positive correlation between the average BAI and the total BAI.In the middle age,the BAI growth of grade V and VI were the fastest.The correlation coefficient between the age and the total BAI and the average BAI were-0.424^*and 0.332 respectively.The age of the middle age level was negatively correlated to the total BAI,and positively correlated to the average BAI.In the aging stage,the Larix chinensis’ BAI of the gradeⅦandⅧgrew the fastest.The growth of the Larix chinensis in 140¹80a was the faster.The correlation coefficients between the age and the total BAI and the average BAI were 0.965^**and-0.969^**respectively.The growth fluctuation of the aging Larix chinensis was relatively stable.The results of the simulation through the ARIMA model showed that the BAI growth of the young Larix chinensis had an obvious fluctuation trend.After 10 a,the growth trend of the BAI began to be slow,with small growth fluctuations.The overall trend was rising steadily.The growth trend of Larix chinensis in the middle age was:the fluctuation of the growth trend was great.The overall growth trend was growing fast,and the maximum growth was about80 a,which belongs to the rapid growth stage.The BAI of the aging Larix chinensis grew rapidly around 100 a and the first peak of its growth was around 140 a,when the BAI growth trend of Larix chinensis was very obvious,and the growth rate would be gradually weaken because of the increase of the age.The growth of Larix chinensis in this age was slow and gradually decayed.