A Novel Comprehensive Evaluation Method of Forest State Based on Unit Circle

Ganggang Zhang,Yanbo Hu,Gongqiao Zhang,Zhonghua Zhao,Gangying Hui

doi:10.3390/f10010005

Ganggang Zhang, Yanbo Hu + Show 3 more

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https://doi.org/10.3390/f10010005

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Abstract

Comprehensive evaluation of forest state is the precondition and critical step for forest management. To solve the problem that the radar plot and unit circle only focus on the value of each the evaluation index, this paper proposes a novel method for comprehensively and simultaneously evaluating the functionality and inhomogeneity of forest state based on the modified unit circle method. We evaluated the forest state of the Quercus aliena BL. var. acuteserrata Maxim. ex Wenz. broad-leaved mixed forest in the Xiaolong Mountains Forest Area of Gansu Province and the Pinus koraiensis Sieb. et Zucc. broad-leaved mixed forest in Jilin Province in China. According to the principle of comprehensive, scientific and operability, 10 evaluation indices on forest structure and vitality were selected to construct the evaluation indicator system. Each index was normalized based on the assignment method and ensured to be strictly positive based on reciprocal transformation method. The areas and arc length of the closed graph, formed by connecting every two adjacent indicators, in the radar plot and unit circle were extracted. Based on the isoperimetric theorem (isoperimetric inequality), a comprehensive evaluation model was constructed. Compared with radar chart and unit circle method, each index in the newly proposed unit circle method is represented by an independent sector region, reflecting the contribution of the index to the overall evaluation result. Each index has the same relative importance weight, contributing to the estimation the relative sizes of each aspect of forest state. The unique area and arc length of the closed graph help summarize the overall performance with a global score. The expression effect of improved unit circle has been enhanced, and as an English proverb put it, “A picture is worth a thousand words.” The new proposed method simultaneously evaluates the functionality and inhomogeneity of the forest state and it is a powerful tool for the diagnosis of forest state problems and the decision-making of forest management.

Highlights

Forest state is the state and properties of a stand of trees in natural habitats [1]
Forest state is directly related to the necessity and urgency of forest management
Forest state evaluation is the precondition of forest management activities, the core task of evaluation and decision-making are the “measures” and “choice”, respectively [2]

Summary

Introduction

Forest state is the state and properties of a stand of trees in natural habitats [1]. It is the specific expression of forest condition at present and the basic of the growth potential and development direction in the future. Forest state is directly related to the necessity and urgency of forest management. Forest state evaluation is the precondition of forest management activities, the core task of evaluation and decision-making are the “measures” and “choice”, respectively [2]. Constructing a scientific index system and choosing a reasonable method for evaluation are the key prerequisite factors to compare different forest states and establish supporting management measures. Many researches have been completed based on forest state characteristics, for example, the method of forest

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