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Information Entropy Measures for Stand Structural Diversity:Joint Entropy

Forestry Studies in China 2004年第2期6卷 12-15页

作者： LeiXiangdong luyuanchang InstituteofForestResourceInformationTechniques ChineseAcademyofForestryBeijing100091P.R.China

Structural diversity is the key attribute of a stand. A set of biodiversity measures in ecology was introduced in forest management for describing stand structure, of which Shannon information entropy (Shannon index) has been the most widely used measure of species diversity. It is generally thought that tree size diversity could serve as a good proxy for height diversity. However, tree size diversity and height diversity for stand structure is not completely consistent. Stand diameter cannot reflect height information completely. Either tree size diversity or height diversity is one-dimensional information entropy measure. This paper discussed the method of multiple-dimensional information entropy measure with the concept of joint entropy. It is suggested that joint entropy is a good measure for describing overall stand structural diversity.

关键词： stand structural diversity Shannon index joint entropy conditional entropy

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A New Function for Modelling Diameter Frequency Distribution in the Tropical Rain Forest of Xishuangbanna,Southwest of China

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Forestry Studies in China 2003年第2期5卷 1-6页

作者： luyuanchang LeiXiangdong JiangLei InstituteofForestResourceInformationTechniques ChineseAcademyofForestryBeijing100091P.R.China SouthwestForestryCollege Kunming650224P.R.China

Permanent plots in the montane tropical rain forests in Xishuangbanna, southwest China, were established, and different empirical models, based on observation data of these plots in 1992, were built to model diameter frequency distributions. The focus of this study is on predicting accuracy of stem number in the larger diameter classes, which is much more important than that of the smaller trees, from the view of forest management, and must be adequately considered in the modelling and estimate. There exist 3 traditional ways of modelling the diameter frequency distribution: the negative exponential function model, limiting line function model, and Weibull distribution model. In this study, a new model, named as the logarithmic J-shape function, together with the others, was experimented and was found as a more suitable model for modelling works in the tropical forests.

关键词： tropical forests diameter distribution modelling logarithmic J-shape function

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