Roads & SDGs, tradeoffs and synergies: learning from Brazil’s Amazon in distinguishing frontiers

To reduce SDG tradeoffs in infrastructure provision, and to inform searches for SDG synergies, the authors show that roads’ impacts on Brazilian Amazon forests varied significantly across fron¬tiers. Impacts varied predictably with prior development – prior roads and prior deforestation – and, further, in a pattern that suggests a potential synergy for roads between forests and urban growth. For multiple periods of roads investments, the authors estimate forest impacts for high, medium and low prior roads and deforestation. For each setting, census-tract observations are numerous. Results confirm predictions for this kind of frontier of a pattern not consistent with endogeneity, i.e., short-run forest impacts of new roads are: small for relatively high prior development; larger for medium prior development; and small for low prior development (for the latter setting, impacts in such isolated areas could rise over time, depending on interactions with conservation policies). These Amazonian results suggest ‘SDG strategic’ locations for infrastructure, an idea the authors note for other frontiers while highlighting major differences across frontiers and their SDG opportunities.

为缓解基础设施供给中可持续发展目标（Sustainable Development Goals, SDG）间的权衡矛盾，并为探寻可持续发展目标协同路径提供参考，研究团队证实，巴西亚马逊林区的道路建设影响在不同开发前沿间存在显著差异。道路的影响可依据前期开发情况——包括既有道路分布与既往森林砍伐状况——进行预测，且其影响模式还显示，森林保护与城市扩张之间可通过道路建设实现潜在协同。针对多轮道路投资周期，研究团队针对前期道路覆盖与森林砍伐程度分别处于高、中、低水平的场景，估算了道路建设对森林的影响。针对每一类场景，人口普查区（census tract）观测样本量均较为充足。研究结果证实了这类开发前沿的相关预测，其影响模式并不符合内生性问题的特征，即新建道路的短期森林影响呈现如下规律：前期开发程度较高的区域，森林受影响程度较低；前期开发程度中等的区域，森林受影响程度更高；而前期开发程度较低的区域，森林受影响程度同样较低（针对后者这类偏远区域，其影响可能随时间推移而上升，具体取决于与保护政策的交互作用）。此次亚马逊区域的研究结果表明，基础设施布局可选择符合‘可持续发展目标战略’的区位，研究团队指出这一思路同样适用于其他开发前沿，并强调不同开发前沿之间存在显著差异，且各自的可持续发展目标实现路径也各不相同。