Measuring the effectiveness of protected area networks in reducing deforestation
Measuring the effectiveness of protected area networks in reducing deforestation
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DOI：
10.1073/pnas.0800437105
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发表时间：
2008-10-21
影响因子：
11.1
通讯作者：
Robalino, Juan A.
中科院分区：
文献类型：
--
作者：
Andam, Kwaw S.;Ferraro, Paul J.;Robalino, Juan A.
减少热带森林砍伐的全球努力在很大程度上依赖于建立保护区。衡量这些地区的有效性是困难的，因为无法直接观察到在没有法律的保护的情况下会发生的毁林量。传统的评估保护区有效性的方法可能会有偏差，因为保护不是随机分配的，而且保护可能会导致砍伐森林的溢出效应（迁移）到邻近的森林。我们证明，有效性的估计，可以大大提高控制沿沿着尺寸，可观察到的偏差，测量空间溢出，并测试潜在的隐藏偏差估计的敏感性。我们采用匹配的方法来评估1960年和1997年之间的哥斯达黎加著名的保护区系统对森林砍伐的影响。我们发现，保护减少了森林砍伐：如果没有保护，大约10%的受保护森林将被砍伐。传统的方法来评估保护的影响，无法控制可观察到的协变量与保护和森林砍伐，大大高估了避免森林砍伐（超过65%，根据我们的估计）。我们还发现，从受保护的森林到未受保护的森林的砍伐溢出效应可以忽略不计。我们的结论对潜在的隐藏偏差以及建模假设的变化具有鲁棒性。我们的研究结果表明，通过适当的经验方法，保护科学家和政策制定者可以更好地了解人类和自然系统之间的关系，并可以利用这一点来指导他们保护关键生态系统服务的尝试。
Global efforts to reduce tropical deforestation rely heavily on the establishment of protected areas. Measuring the effectiveness of these areas is difficult because the amount of deforestation that would have occurred in the absence of legal protection cannot be directly observed. Conventional methods of evaluating the effectiveness of protected areas can be biased because protection is not randomly assigned and because protection can induce deforestation spillovers (displacement) to neighboring forests. We demonstrate that estimates of effectiveness can be substantially improved by controlling for biases along dimensions that are observable, measuring spatial spillovers, and testing the sensitivity of estimates to potential hidden biases. We apply matching methods to evaluate the impact on deforestation of Costa Rica's renowned protected-area system between 1960 and 1997. We find that protection reduced deforestation: approximately 10% of the protected forests would have been deforested had they not been protected. Conventional approaches to evaluating conservation impact, which fail to control for observable covariates correlated with both protection and deforestation, substantially overestimate avoided deforestation (by over 65%, based on our estimates). We also find that deforestation spillovers from protected to unprotected forests are negligible. Our conclusions are robust to potential hidden bias, as well as to changes in modeling assumptions. Our results show that, with appropriate empirical methods, conservation scientists and policy makers can better understand the relationships between human and natural systems and can use this to guide their attempts to protect critical ecosystem services.