We revisit an unanswered and yet critical question in forest policy design: does a price or quantity instrument achieve a better social outcome when the government does not have perfect information. This is a common question in environmental regulation, but in the forest policy literature an equivalence between these instruments has historically been presented, albeit under perfect information. In the forestry case one might be tempted to simply defer to Weitzman (1974), who derived rules for prices versus quantity policy choices when either marginal abatement costs or marginal benefits of polluting emissions are unknown to the policy maker. These rules may not be transferrable to the forestry problem, however. We develop a framework of marginal costs and benefits based on a standard rotation model, showing that uncertainty leads to (very) different results than in the emissions literature. For example, we find that the slopes of marginal costs and benefits and the difference between the expected values of uncertain parameters and their realizations matter differently for the forest policy case. We also find that symmetric over- and under-estimation around true parameter values can result in asymmetric changes in marginal cost curves. Most importantly, we find that even the size of this difference now matters to the price versus quantity policy choice. Our results both draw into question whether Weitzman rules simply apply to forest resources, and they suggest that our new approach should be used for evaluating alternative forestry policies to achieve public goods goals.

我们重新审视森林政策设计中一个尚未解答但又至关重要的问题：当政府没有完善的信息时，价格或数量工具能否取得更好的社会成果。这是环境监管中的一个常见问题，但在森林政策文献中，尽管信息不完善，但历史上已经提出了这些工具之间的等效性。在林业案例中，人们可能会倾向于简单地遵循Weitzman（1974）的观点，当政策制定者不知道边际减排成本或污染排放的边际收益时，他得出了价格与数量政策选择的规则。然而，这些规则可能不适用于林业问题。我们基于标准轮换模型开发了一个边际成本和收益框架，表明不确定性导致与排放文献中的结果（非常）不同。例如，我们发现边际成本和边际效益的斜率以及不确定参数的预期值与其实现之间的差异对于森林政策案例的影响不同。我们还发现，围绕真实参数值的对称高估和低估可能会导致边际成本曲线的不对称变化。最重要的是，我们发现，即使这种差异的大小现在也对价格与数量政策的选择产生影响。我们的结果都引发了对韦茨曼规则是否仅适用于森林资源的质疑，并且它们表明我们的新方法应该用于评估替代林业政策以实现公共物品目标。