Abstract: Abstract: A bivariate Weibull model was used to describe the diameter-age 2-dimension structure of Moso bamboo ( Phyllostachys Pubescens ) forests in Zhejiang province. Date from 245 permanent Moso Bamboo plots out of total of 4250 of Zhejiang Continuous Forest Inventory System were used in this study. These plots were resurveyed in 2004. Survival function of the bivariate Weibull distribution model was discussed in detail, and several expressions of the model were proposed. Both the univariate Weibull diameter and age models were marginal distributions of the bivariate Weibull model. Parameters estimated from marginal distributions were very close to those from the joint distribution. Although this study was on bamboo forests at provincial level, the model and the method developed in this research could be used to other forest types such as arbor forests, at different scales.

Key words: Key words: Moso bamboo ( Phyllostachys pubescens ), diameter, age, bivariate Weibull model, Weibull survival functio