台灣進口製材替代關係分析

Substitution Relationship between Imported Lumber

本文實證分析台灣對製材主要供應國：加拿大、印尼、馬來西亞、美國、紐西蘭、及其餘國家的製材進口需求模式。結果可供吾人瞭解：主要供應國的製材價格變化如何影響各供應國在台灣市場的佔有率。理論基礎包括成本最小化的總進口模型以及個別供應國的市場佔有率方程式。模型假設各供應國的製材並非為完完全替代，而且，不同之替代彈性存在於各供應國之間。模型採用動態觀念的局部修正模式。結果顯示：1990年1月至1999年12月間，不同供應國間的替代彈性有顯著的差別，加拿大-1.05（+0.32）、印尼-1.32（+0.14）、馬來西亞-0.61（+0.17）美國-1.95（+0.23）、紐西蘭-2.13（+0.24）。總合進口製材價格長期彈性為-2.95（+1.17）。其次，根據替代彈性、總合進口製材價格彈性、以及各供應國的市場佔有率，計算出自身價格與交叉價格彈性。自身價格彈性介於加拿大的-1.27與紐西蘭的-2.16之間，各供應國間的交叉價格彈性皆小於1。自身與交叉價格彈性分別可被分離成兩種效果：替代效果與市場擴張（所得）效果。前者衡量特定供應國製材價格上漲時，其他供應國替代該國製材進口的幅度；後者則衡量因該價格變化，導致台灣進口製材的縮減幅度。

Empirical models were obtained for the Taiwan's demand for lumber imports from the Canada, Indonesia, Malaysia, United States, New Zealand, and the rest of the world. The theory consisted of a cost-minimizing aggregate Taiwan's demand for imports and of share equations for each country were not perfect substitutes and there existed different elasticities of substitution between countries.The results showed that long-term elasticity of substitution significantly differed among countries: -1.05( + 0.32) for the Canada, -1.32( + 0.14) for the Indonesia, -0.61(+0.17) for the Malaysia, -1.95( + 0.23) for the United States, -2.13( + 0.24) for the New Zealand. The price elasticity of aggregate demand for lumber imports was -2.95( + 1.17). Own-price and Cross-price elasticities were then obtained from the elasticity of substitution, the share of each country in Taiwan's market, and the elasticity of total imports with respect to price. Own price elasticity ranged from -1.27 for Canada to -2.16 for New Zealand. Cross-price elasticities between individual country were all less than one. It is shown how the effect of two parts: a substitution effect, measuring the price-induced substitution of imports from one country by those from other countries, and a market expansion effect, measuring the impact of the rise in price of particular country on total Taiwan's woodpulp imports.