High-severity fire in forested landscapes often produces a post-fire condition of high shrub cover and large loads of dead wood. Given the increasing patch size of high-severity fire and the tendency for these areas to reburn at high severity in subsequent wildfires, post-fire management often targets restoration of these areas. However, these areas are challenging to manage, in part due to limited knowledge of post-fire fuel dynamics over space and time and uncertainties in how specific fuel components such as snags and logs influence future fire severity. In this study, we used high-resolution aerial imagery collected nine years after a wildfire to measure snags, logs, and shrub cover within high-severity patches, and to assess how fuel development influenced reburn severity in a subsequent wildfire. The abundance of snags, logs, and shrubs following high-severity fire varied with elevation and slope steepness; however, generalized additive models explained only 6 to 21% of their variation over the post-fire landscape. High densities of both snags and logs were associated with high reburn severity in a subsequent fire, while shrub cover had a marginally insignificant (P = 0.0515) effect on subsequent fire severity. Our results demonstrate that high levels of large dead wood, which is often not considered in fire behavior modeling, corresponded with repeated high-severity fire effects. Future research should leverage the increasing availability of high-resolution imagery to improve our understanding of fuel load patterns in space and time and how they may impact landscape resilience to facilitate management planning for post-fire forest landscapes.

中文翻译：

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美国内华达山脉混合针叶林大火后的燃料动态和重燃严重性

森林景观中的高烈度火灾通常会在火灾后产生高灌木覆盖率和大量枯木的状况。鉴于高强度火灾的斑块大小不断增加，并且这些区域在随后的野火中有重燃的趋势，因此，火灾后的管理通常以恢复这些区域为目标。但是，这些地区的管理面临挑战，部分原因是对火后燃料在空间和时间上的动态了解有限，以及不确定的燃料成分（例如碎屑和原木）如何影响未来火势的不确定性。在这项研究中，我们使用了野火九年后收集的高分辨率航空影像，以测量高强度斑块中的障碍物，原木和灌木覆盖，并评估燃料的发展如何影响随后的野火中的再燃严重性。大量的障碍物，原木，高强度火灾后的灌木随海拔和坡度的变化而变化；但是，广义的加性模型仅解释了火灾后景象变化的6％至21％。断枝和原木的高密度与随后火灾中的高重烧严重性相关，而灌木覆盖对随后火灾的影响微不足道（P = 0.0515）。我们的结果表明，高水平的大死木（通常在火灾行为建模中不予考虑）与重复的高严重火灾效应相对应。未来的研究应利用高分辨率图像的日益增加的可用性，以增进我们对空间和时间上的燃料负荷模式以及它们如何影响景观弹性的理解，以促进对森林火灾后景观的管理规划。