| Abstract: | 溼地資源利用目標在於確保能永世代為人類提供生存、需要與需求的財貨與服務,不過在朝向永續利用邁進路徑中,我們常忽略溼地利用機會成本的問題,致使溼地利用政策常走向「全有」、「全無」或「零和」的利用模式。為了改善或舒緩這種利用衝突的情況,以Hicks-Kaldor補償原則或Pareto-improvement效率準則出發的「外部效果內部化」政策手段,或許是一個值得我們參考的做法。為了落實此政策手段,溼地保育評價便成為一個我們不能回避的工作。由於情境評價法(CVM)可同時評估使用價值與非使用價值,因此受到許多研究者的青睬。雖然利用情境評價法評估溼地保育價值,對溼地永續利用與合理決策過程有其適用性與必要性,但是前提條件是這些評價結果需具備相當程度的有效性(validity)與可信度(reliabilty)。為了探索情境評價結果是否具有理論有效性,本研究利用有母數與無母數統計方法檢測溼地維護方案評價是否在「巢狀效果」,並探索其形成的因素。< 檢測結果顯示,不論有無剔除虛偽零出價、台北市與台南縣或「由上而下」與「由下而上」詢價次序,大致呈現單一溼地維護方案與五大溼地維護方案評價結果無顯著差異的情況,即存在巢狀效果;四大溼地維護方案與五大溼地維護方案結果呈現顯著差異的情況,即不存在巢狀效果。至於巢狀效果產生的原因, Kahnman and Knetsch(1992)以「道德滿足購買」(the purchase of moral satisfaction)因素解釋此現象,本研究偏好以「供給不確定」來解釋此現象,因為檢測結果發現溼地維護方案之空間範圍愈大主觀供給機率愈小。< 由於檢測結果發現,利用情境評價法評估溼地保育價值,仍未能滿足有效性的條件,因此溼地情境評價結果在現階段仍不適宜做為溼地政策的應用。就本研究實證結果,為了改善情境評價之巢狀效果現象,供給不確定因素的改善或許是一個我們可以思考的方向。<
The goal of wetland resource use is to ensure it can provide human with various kinds of goods and services which support human lives, needs and demands. However, the problem of opportunity cost of wetland uses is always neglected, which results in the "all or nothing" or "zero-sum" policy of wetland resource use. To improve or mitigate this conflict, an "internalized externality" policy of Hicks-Kaldor compensation or Pareto improvement criteria might be a worthwhile approach. To put this into effect, the evaluation of wetland resources is a necessary task for planners and managers. Because the contingent valuation method (CVM) can assess both use and non-use values or wetland resources, it has been adopted widely. Although it is necessary to use the CVM to evaluate wetland conservation values, the premise of relative validity and reliability must be met. To explore whether the CVM has theoretical validity, this research adopts parametric and nonparametric statistical analyses to examine whether wetland conservation projects demonstrate the "embedding effect". Furthermore, the causes of the embedding effect are explored as well.< The results show that, with or without protest zero prices, samples from Taipei and Tainan or "bottom-up" and "top-down" price inquiry exhibit no significant differences between the single and the five preservation projects. Restated, the embedding effect exists. On the other hand, significant differences exist between the four and five wetland preservation projects, suggesting that the embedding effect does not exist. As to the causes of the embedding effect, the "purchase of moral satisfaction" is suggested by Kahnman and Knetsch (1992). The statistical results show that the larger the geographical space is given to wetland preservation programs, the smaller the subjective supply probability will be. Therefore, the "supply uncertainty" is adopted in this research to explain the embedding effect.< Judged from the statistical results, using the CVM to evaluate wetland conservation values cannot meet the validity criteria. This suggests that, at present stage, the CVM might not be suitable for wetland policy implementation. As far as this research is concerned, to improve the embedding effect of the CVM, the improvement of supply uncertainties may be a possible direction for future research.< |
