Studies on the Estimate Method for Average Stem Density
- Received Date: 1997-06-05
- Available Online: 2012-03-17
Abstract: The model y=bx+e is used to estimate the density of stem,where y is dry weight, x is volume, b is density and e is error.According to the relationship between variance of y and x, there are three methods to estimate b: (1)variance of y is uncorrelated with x ;(2)the relationship between the variance of y and x is a positive correlation,or δyx2=xδ2 ;(3)the relationship between the standard deviation of y and x is a positive correlation, or δyx=xδ.In this paper,the three methods were applied to estimate the average density of stem wood and bark,and the differences of the density in different positions of a tree and in different age class were analyzed with dummy variable method.The results showed:the effect of method (1) is better than the others.The differences of the density in different positions of a tree and in different age class are not significant.Same average density can be used to estimate stem dry weight of the same species of trees.