Diameter and Height Distributions of Natural Even-Aged Pine Forests (Pinus sylvestris) in Western Khentey, Mongolia

蘇格蘭松同齡天然林的直徑與樹高分佈

Khongor Tsogt ； Tsogt Zandraabal ； 林金樹(Chin-Su Lin)

《台灣林業科學》 28卷1期 (2013/03) Pp. 29-41

https://doi.org/10.7075/TJFS.201303_28(1).0003

摘要

本文以蒙古國Khentey省的西部天然同齡林為研究地區，利用Burr、Dagum以及Johnson SB機率密度函數模擬配適蘇格蘭松（Pinus sylvestris L.）不同齡級的林分胸高直徑以及樹高的分佈模式。結果顯示：10年生以及40年生齡級的林分直徑分佈為向左偏斜的分佈（negatively skewed distribution），60年生的齡級則為常態分佈（normal distribution）；10年生以及60年生齡級的林分樹高分佈為向左偏斜的分佈，40年生齡級的林分的立木樹高呈離散的分佈，並無明顯的分佈特徵。依據配適函數模型的結果，蘇格蘭松同齡天然林的林分直徑以及樹高分佈可以利用Dagum、Burr、Johnson SB函數配適之，但由模型統計值顯示Dagum函數模型對於左偏分布的林分結構配適效果較為理想，而Johnson SB函數對於常態的林分結構配適效果較佳。林分結構資料顯示：若蘇格蘭松同齡天然林分有足夠的林分空間以供生長，林分的直徑結構會呈現很明顯的左偏分布，經過40年的生長期，會發展成為常態分佈；如果林分的生長空間有限，則林分的樹高結構將會由左偏現象發展為不規則結構。60年齡級以下的林分（AG1、AG3）樹高結構為左偏分布，但是如果林分密度太高將造成離散型結構，無明顯的函數分布型態。

關鍵字

胸高直徑 ； 樹高 ； 左偏分佈 ； 蘇格蘭松

並列摘要

The purpose of this study was to find a suitable probability density function (PDF) to model the diameter at breast height (dbh) and height distributions of even-aged pine (Pinus sylvestris L.) forests. For the study, three different age-classes (AGs) of pine forests were used. Burr, Dagum, and Johnson SB distributions were applied due to their flexible properties. Result showed that dbh distributions of the 10~15- (AG1) and 40~45-yr (AG2) stands were left-tailed, while the 60~65- yr (AG3) stand was normally skewed. Height distributions of the AG1 and AG3 stands were left-tailed, while that of the AG2 stand showed no obvious distribution shape, due to its discrete height distribution. A distribution study revealed that in left-tailed forests, dbh and height distribution shapes were best approximated by the Dagum distribution. In the case of the normal distribution shape, the Johnson SB was better than the Burr and Dagum ones. Based on these results, we concluded that dbh distributions of even-aged AG1 and AG2 forests were heavily left-tailed, and the forest structure tended to normal for the AG3 forest. The height distribution is left tailed (AG1 and AG3) if a forest's height growth is not constrained by space, while it will become discrete in a high-density stand (AG2).

並列關鍵字

diameter at breast height ； height ； left-tailed distribution ； Scots pine (Pinus sylvestris L)