A Preliminary Study on the Structure and the Estimation of Growth of Cryptomeria Fortunei Plantation in the Western Borders of the Sichuan Basin
Zhao XiaoYun (Sichuan Forestry School)
The method of multivariate statistical analysis was applied to study the density and the structure of diameter-tree number of Cryptomeria fortunei plantation in the western borders of the Sichuan Basin. And important factors (age,site index and average diameter of stands) that affected the density of C. fortunei plantation were sifted ou. And the model that estimated the density of C. fortunei plantation was established. On the basis of the table for determining gamma value and coefficient of variation of diameter of c parameter of Weibull function offered by Nishizawa Seikyu( 1978) , Weibull function was fitted with the data from 48 standard plots. The results of X_2-test showed that X_2 values of 33 standard plots came to extremely significant level (a=0. 01).and 10 standard plots came to significant level (a=0. 05).and other 5 standard plots did not fit into Weibull function. The expression of regression was made between b,c parameters of Weibull function and the structure factors of C. fortunei plantation. And the predicted model was es tablished that estimated b.c parameters with structure factors easy to be measureted in the stands. Based on the models above,the structure and the growth of C. fortunei plantation were estimated.The tested result showed that the estimted values of the models came to the precision demand.and the models can be used for the prediction of resources,management and thinning of forest.