Factor analysis of productivity is an important method in comparing and evaluating the productive potentiality and management level of bamboo species. This study discussed the relationship between factors such as economic index, number of standing culms, leaf area index, habitat quality and growth levels. It was found that: (1) Economic index(Ⅰ) was equivalent to the quotient of the annual economical output(E)and the annual stand biomass (B), i. e. I=E/B. Under the same site and managing conditions, the unit area output increased with the ecofiomic index. Generally, clump-forming bamboos are better than scattered bamboos by about 1 time higher in the economic index. 30 percent more economic index could be expected through intensive management. (2) Number of standing culms is used to examine the appropriate density. Based on 5.29 m~2 per mu of section area at breast height from the high-yield sample stand in Zhejiang in 1950',the standing number was figured out by the breast-height section area per mu of Phyllostachys pubescens divided by 5.29m~2. (3) The total leaf area (La) divided by the forest land area (A) was the leaf area index(LAN), i. e. LAN=LA/A. LAN could be determined by leaf weight per unit area (Lg) times leaf area per Kg (La/Kg) and then divided by forest land area (A), i. e. LAN= (Lg×La/Kg)/A Based on complete data, the leaf area per Kg of Phyllostachys pubescens was figured to be 9.93m. But it varied within different age classes. For age class Ⅰ, it was 11.63m~2, Ⅱ, 9.24 m~2 Ⅲ, 9.54 m~2 and Ⅳ 9.31m~2 (4) Usually the quotient of the age divided by the height of trees is used to calculate the habitat quality—the comprehensive quality of soil fertility, slope degree, position, climate and other factors. For Bamboos, however, it is better to take the average DBH as measuring standard which was recommended by the author early in 1950s' as GROWTH LEVEL METHOD. The standard growth levels of some species were listed in the table 5.
Journal of Bamboo Research