USDA Forest Service, Rocky Mountain Research Station, Missoula Fire Sciences Laboratory, Missoula, MT, USA.
USDA Forest Service, International Visitor Program and Portland State University, Department of Environmental Science and Management, Portland, OR, USA.
Risk Anal. 2018 Oct;38(10):2105-2127. doi: 10.1111/risa.12999. Epub 2018 Apr 25.
We assessed transboundary wildfire exposure among federal, state, and private lands and 447 communities in the state of Arizona, southwestern United States. The study quantified the relative magnitude of transboundary (incoming, outgoing) versus nontransboundary (i.e., self-burning) wildfire exposure based on land tenure or community of the simulated ignition and the resulting fire perimeter. We developed and described several new metrics to quantify and map transboundary exposure. We found that incoming transboundary fire accounted for 37% of the total area burned on large parcels of federal and state lands, whereas 63% of the area burned was burned by ignitions within the parcel. However, substantial parcel to parcel variation was observed for all land tenures for all metrics. We found that incoming transboundary fire accounted for 66% of the total area burned within communities versus 34% of the area burned by self-burning ignitions. Of the total area burned within communities, private lands contributed the largest proportion (36.7%), followed by national forests (19.5%), and state lands (15.4%). On average seven land tenures contributed wildfire to individual communities. Annual wildfire exposure to structures was highest for wildfires ignited on state and national forest land, followed by tribal, private, and BLM. We mapped community firesheds, that is, the area where ignitions can spawn fires that can burn into communities, and estimated that they covered 7.7 million ha, or 26% of the state of Arizona. Our methods address gaps in existing wildfire risk assessments, and their implementation can help reduce fragmentation in governance systems and inefficiencies in risk planning.
我们评估了美国西南部亚利桑那州的联邦、州和私人土地以及 447 个社区的跨境野火暴露情况。该研究根据模拟点火的土地所有权或社区以及由此产生的火灾边界，量化了跨境（入境、出境）与非跨境（即自我燃烧）野火暴露的相对程度。我们开发并描述了几种新的指标来量化和绘制跨境暴露情况。我们发现，入境跨境火灾占联邦和州立土地上大面积土地燃烧总面积的 37%，而 63%的燃烧面积是由该土地内的点火引起的。然而，对于所有土地所有权，所有指标都观察到了大量的土地间变异。我们发现，入境跨境火灾占社区内总燃烧面积的 66%，而自我燃烧点火占 34%。在社区内燃烧的总面积中，私人土地所占比例最大（36.7%），其次是国家森林（19.5%）和州立土地（15.4%）。平均有七个土地所有权为个别社区贡献了野火。受州和国家森林土地上点火影响的野火对建筑物的年暴露率最高，其次是部落、私人和 BLM。我们绘制了社区火灾流域图，即点火可以引发火灾并蔓延到社区的区域，并估计这些区域覆盖了 770 万公顷，占亚利桑那州的 26%。我们的方法解决了现有野火风险评估中的差距，其实施有助于减少治理系统的碎片化和风险规划的低效率。
