Study On Height-diameter Models

Every investigation factor is closely related with each other, study on these correlations is the foundation of forest structure and the growth law. In the actual forestry resources survey there are many elements affect investigation factors, such as diameter, height, age, site condition and so on. And the most important factors are diameter and height at the same time they are also the key index of stand growth. There is a positive correlation between them and the age of the tree, also the diameter and height. Height-diameter model plays an important role in the production practice and scientific research of the forest.This thesis adopts the year of1997’s three test samples data of Dong Fang Hong forest farm which is belong to Dai Ling forestry bureau in the Heilongjiang province. Then research the best height-diameter of the main tree spices in the test samples by regression theory and nonlinear measurement error theory. The research work and the conclusion are as follows:First, using regression theory we give the statistical analysis for the test samples, according to correlation coefficient and regression sum of squares we choose the optimal height-diameter model from the ten commonly used models. Then this thesis estimates the parameters and determines growth equation for the main spices. The results show that the function H=D21(a+bD)2can explain the relationship of Korean pine and birch between height and diameter best and they are less influenced by the forest stand. On the other hand, the height-diameters of linden Acermonp and spruce are big influenced by the forest stand, in different stand, there are different height-diameter models; in that way we should choose different height-diameter models according to different stand type in the growth simulation.Then, using nonlinear measurement error theory we discuss the statistical analysis for the test samples, according to correlation coefficient and residual sum of squares we choose the optimal height-diameter model from the ten commonly used models. Then this thesis estimated the parameters and determined growth equation for the main spices, finally compared the measured value and optimal value. The result shows that the function H=a+bD+cD2can explain the relationship of Korean pine and birch between height and diameter best and they are less influenced by the forest stand. On the other hand, the height-diameters of linden Acermonp and spruce get the same conclusion as the above research. The further proved we should choose different height-diameter models according to different stand type in the growth simulation.