Stand Structure Analysis And Effects Of The Factors On Under Brach Height Of Phyllostachys Edulis

In this paper, stand spatial structure of Phyllostachys edulis forest was investiga- ted in Sanming city, Fujian province. Then used partial correlation analysis, stepwise regression analysis and principal component analysis to analyse the factors which affected the growing of under brach height and DBH.The results as follow:(1) The spatial allocation was simple and culms were more aggregative in this plantation. The distribution of neighborhood comparison changed with a fluctuant pattern, and the proportions of middle and inferiority stood much more. There was a scale effect approved on even degree. The age of the bamboos was researched and it showed that the uniform angle index at different ages had no significanten correlacations, so as to the results of even degree.(2) Then used the ten factors to make partial correlation analysis, the result showed uniform angle index(X10), canopy density(X5) and age(X6) were the main factors on growing of under brach height;Uniform angle index(X10), age(X6), slope position(X3), gradient(X1) and canopy density (X5) were the main factors on growing of DBH.(3) Took the ten factors to make stepwise regression analysis, the result showed canopy density (X5) and uniform angle index(X10) were the main factors on growing of under brach height, the mathematical model:Y1=5.088+3.685X5-2.380X10; Humus thickness(X7), uniform angle index(X10) and canopy density(X5) were the main factors on growing of DBH, the mathematical model:Y2=8.985+2.477X5+0.198X7-2.979X10.(4) Then took the ten factors to make principal analysis, made the ten variables turn to three principal components, and this three components' cumulative proportion got to 92.690%.The first principal component responsed the effects of gradient(X2), humus thickness(X7) and uniform angle index(X10); The second principal component responsed the effects of uniformity(X8); The third principal component responsed the effects of ascept(X2).