Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/65885
標題: 大安溪事業區林木經營區針葉樹人工林疏伐計畫之評估
Evaluation of Thinning Project for Conifer Plantations in Timber Management Zone of Da-An Shi Working Circle
作者: 紀儀芝
Chi, Yi-Chih
關鍵字: Thinning;疏伐;Project evaluation;Simple additive weighting method(SAW);計畫評估;簡單加權法
出版社: 森林學系
摘要: 
疏伐作業為森林撫育重點工作之ㄧ,爲能增加林木生長、減少競爭,促進保留木相對生長空間,適當的疏伐作業不可缺少。近年來由於世界森林的走向朝向以生態系經營為主要政策方向,台灣森林經營政策亦隨著潮流而進行,而減少對傳統林木經營的課題進行探討,現今由於林務局致力於森林撫育工作的推行,並於全省設置多處疏伐作業的示範區,因此疏伐的相關課題再次被重視,有鑑於此,本研究以東勢林區管理處大安溪事業區林木經營區針葉樹人工林為研究範圍,透過計畫評估之簡單加權法,以造林台帳資料為基礎資料,林分為評估單元,訂定經濟與公益兩項準則,綜合評估六樹種各林分之最適疏伐作業。
由於各林分栽植年代不同、輪伐期不同,因此將六樹種分為未達輪伐期樹種與達輪伐期樹種兩部分進行分析。前者之計畫方案依據株數百分比分為強度疏伐(45%)、中度疏伐(35%)及不處理三方案,後者則另外加入皆伐處理共四方案。經濟準則分析方面,首先依據各樹種適當材積式分別計算林分或單木材積,再以不同方案之株數百分比求算各樹種不同處理之疏伐材積量,另外,由於疏伐處理對主伐材積收穫量有一定的影響,因此按照林分年平均生長材積同時計算各疏伐處理留存木之主伐收穫材積。隨後,並根據推估所得材積計算各疏伐及主伐成本與收益,再以淨現值法評估之。而公益性準則部分,除依據留存木材積推估各林分至輪伐期之碳貯存量外,並計算林分密度百分比,以評估疏伐對水土保持之影響。最後以簡單加權法,權重之比例以經濟性準則:公益性準則分別為0.5:0.5、0.7:0.3及0.3:0.7三種權重方式綜合評估各林分之最適疏伐作業。
研究結果顯示,純粹以經濟性準則評估結果,紅檜、扁柏、台灣杉、雲杉適合採強度疏伐,杉木、柳杉適合採皆伐作業。而單以公益性準則評估結果而言,四種未達輪伐期之樹種大致上適合中度疏伐,杉木、柳杉則適合皆伐處理。經簡單加權法綜合評估結果,不論權重比,紅檜、扁柏、台灣杉大多適合採不處理作業,雲杉適合中度疏伐,達輪伐期之杉木、柳杉則至少需採強度疏伐以上之處理。

Thinning operation is an important subject on forest tending. It not only increases timber growth and decreases competitions but also provides better growing space for trees and is considered an operation that should not be neglected. Traditional forest management has been overlooked since ecosystem management is more preferable to the world trend. However, forest tending is nowadays one of the major tasks for Taiwan Forest Bureau, by which many thinning demonstration areas have been established to observe the changes come after thinning operation, therefore forest thinning is once again under the spot light.
Although thinning operation is a fundamental operation for timber management, the way to choose an appropriate project is even more important. The object of this research is to provide an evaluation method for choosing the appropriate thinning project. Conifer planations of six tree species in the timber management zone of Da-An Shi working circle were used as study subjects and attribute data of these planations were collected to calculate timber volumes in this research. Simple additive weighting method (SAW) was applied to integrate economic and public welfare criteria, different weight rates of 0.7:0.3, 0.5:0.5 and 0.3:0.7 were calculated as the two criteria to evaluate four different thinning projects. The four projects were accomplished by treatments of cutting stems as clear cutting(100%), heavy thinning(45%), intermediate thinning(35%) and without thinning(0%). The results are as follows:
When compared under the economic criterion of net present value(NPV), the appropriate thinning project for Chamaecyparis formosensis, Chamaecyparis obtuse var. ofrmosana, Taiwania cryptomerioides and Picea morrisonicola turned out to be heavy thinning, and for Cunninghamia lanceolate and Cryptomeria japonica, clear cutting seemed to be more suitable. However, when the public welfare criterion was concerned, intermediate thinning appeared to be a better choice for the four former species, and clear cutting remain suitable for the latter two species. Along with all the weight rates, the final evaluation by SAW showed Chamaecyparis formosensis, Chamaecyparis obtuse var. formosana, and Taiwania cryptomerioides were more suitable for treatment without thinning, Picea morrisonicola were better to be treated with intermediate thinning and Cunninghamia lanceolate, Cryptomeria japonica were more suitable for heavy thinning and clear cutting, respectively.
URI: http://hdl.handle.net/11455/65885
Appears in Collections:森林學系

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