造林獎勵與碳吸存補貼對台灣造林與社會福利的影響

The Impact of Afforestation Support and Carbon Sequestration Subsidy on Forestation and Social Welfare in Taiwan

沈芝貝(Chih-Pei Shen)

指導教授 ： 吳珮瑛

國立臺灣大學/生物資源暨農學院/農業經濟學研究所/碩士(2007年)

https://doi.org/10.6342/NTU.2007.03381

摘要

森林具公共財特性，有共享和不可排他的性質，而私有林業主在以經濟利益為首要考量之前題下，通常沒有能力也缺乏誘因去提供這個無法透過市場機制運作而獲得利益的公益效用。所以為提供農民較大的經濟誘因，促使農民真正從事造林工作，政府應將無法透過市場反應的外部性和公益價值補貼給農民，才能使資源合理配置且有效率利用。然而農業和林業兩部門在土地利用上有著顯著的互競效果，是以大量農地投入造林，雖然可以增加二氧化碳的吸存量，此卻也可能導致農作物價格高漲的另一個問題，同時使得木材價格更加低迷，對整體農林部門之生產者與消費者所能享有之社會福利而言，並不儘然是件好事。亦即過多和過少的造林都可能帶來負面的影響。
有鑑於此，本研究將考量台灣林地特殊的所有權屬型態，在私人經營林地佔全國林地面積比例極低的情況下，立基在森林具有的公私效益基礎上，及林業與農作物互競之出發點上，建構一個平衡農林部門土地利用之概念架構，同時考慮造林面積多寡與競租作物價格高低的關係，考量時間和折現，設計一個更符合林木長期成長所需的決策模型。並比較有無造林獎勵政策，或在造林獎勵政策上加上不同的碳稅補貼時，對台灣整體造林面積的增減和農民造林決策的影響，同時，進一步分析依此而來之社會福利，在不同政策組合下的變化。
結果發現無論是造林獎勵或碳稅補貼皆可使造林面積增加，且碳稅確實有助於延長新植林的砍伐年限。然而當只有造林獎勵而沒有碳稅時，農民在造林獎勵政策結束後五年即有可能將樹木砍伐，且一旦沒有造林獎勵金林農則不願意再繼續投入造林。然而只要給予每公噸碳稅大於100元之補貼，林農其即願意延長其既成林之砍伐年限；每公噸碳稅大於1,000元時，林農即便沒有造林獎勵政策也願意投入造林。是以透過碳稅的補貼將森林之碳吸存效益回饋給造林者，不僅可以誘使其增加造林面積、減緩溫室氣體減量對國內產業所造成的衝擊，進而可解決長期因木材價格低迷導致的林地荒廢及超限利用等問題，並有效利用我國加入WTO後逐年增加的休耕農地，增加平地的綠化面積。

關鍵字

林業獎勵政策 ； 正外部效益 ； 數學規劃 ； 農林部門模型 ； 競租作物 ； 政策模擬

並列摘要

The private forest land owners are normally lack of incentive to provide goods which have public good characteristics through market mechanism. In order to increase the economic incentive for forest farmers in managing the forestation, support and/or subsidy from government with the provision public goods is essential. However, the utilization of private forest land is competitive between cultivating different agricultural crops and growing trees. There are various positive sides of growing trees. Among these, it is to increase the sequestration of carbon dioxide. This, however, might induce the increasing prices of agricultural crops and decreasing price of timbers. As a result, the total benefit or welfare for the producers and consumers both for agricultural and forestry sectors are not necessary positive.
The purpose of this study is to take into account the special forestry land ownership in Taiwan, i. e. very low percentage of private owner forestry land as compared to the total forestry land, and construct a model in which the land utilization between agriculture and forestry is balance. This is a model reflects a long-term decision making that involves changing the acreage of afforestation, prices of competitive agricultural crops, time, and discount rate. Simulations are then performed to compare the scenarios between policy with afforestation support and without support and among policies with afforestation support plus various levels of carbon sequestration subsidies. It is to observe the change of afforestation acreages and social welfare under different combination of policies.
The result has shown that it is capable to increase the afforestation acreages regardless of the policy with afforestation support or carbon sequestration subsidy. Besides, the carbon sequestration subsidy is benefit to prolong the felling age of new forest lands. However, if there is only afforestation support and without carbon sequestration subsidy, farmers might cut down the trees when the silviculture encouragement has ended five years later. And forest farmers are reluctant to invest in afforestation if there is no support for afforestation. It is, however, a subsidy of more than NT$100 per ton on carbon sequestration, forest farmers are willing to prolong the felling age limit for oncoming forests. For carbon sequestration subsidy greater than NT$1,000 per ton, forest farmers are willing to invest in afforestation despite there is no afforestation support.

並列關鍵字

forestry support policy ； positive externality ； mathematical programming ； competitive crops ； agriculture and forest sector model ； policy simulation

參考文獻

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