概似函數法之兩群落共同種類數的估計

A Likelihood Approach to Estimating the Number of Shared Species in Two Communities

莊佳叡(Chia-Jui Chuang) ； 沈宗荏(Tsung-Jen Shen) ； 黃文瀚(Wen-Han Hwang)

《智慧科技與應用統計學報》 10卷2期 (2012/12) Pp. 47-69

https://doi.org/10.29807/JTITAS.201212.0004

摘要

共同種類數是刻劃兩個生態群落共通性的一個基礎生物多樣性指標。傳統上，生態學家大多直接以資料中兩群落均有被觀察到的共同種類數來作為此數的估計值。然而在抽樣收集所得的資料中，經常會有一些物種未被觀察或收集到，因此傳統的方法會低估真正的共同種類數。本文建構樣本資料中物種被觀察次數的機率模型，並以條件概似函數法求得模型中之參數的估計值及導出共同種類數的估計式。文中也以電腦亂數虛擬的族群以及一組兩個實際森林樣區的資料進行模擬分析，據以驗證所提之共同種類數估計式的表現情況。

關鍵字

生物多樣性指標 ； 條件概似函數 ； 物種豐富度 ； 共同種類

並列摘要

The number of shared species is a basic biodiversity index for characterizing the species richness and similarity of two ecological communities. Traditionally, most ecologists estimate the number of shared species by using the naïve estimator, which is simply the number of observed shared species in the sample of data. The resulting naïve estimate generally displays a negative bias due to some of shared species may be absent in the sample. In this study, we develop a probability model on the observed frequency of the sample data. Thus, we estimate the model parameters as well as the number of shared species via a conditional likelihood approach. Simulation studies based on some artificial populations and a census dataset, consisted of two real forest plots, were carried out to evaluate the performance of the proposed method.

並列關鍵字

biodiversity index ； conditional likelihood ； species richness ； shared species