Fire size and severity have increased in the western United States in recent decades, and are expected to continue to increase with warming climate. Habitats for many species are threatened by large and high-severity fires, but the effect of spatial scale on the relationship between fires and habitat modifications is poorly understood. We used the 2011 Wallow Fire—the largest wildfire in the state history of Arizona, USA—as a case study and assessed changes in predicted nesting habitat of the threatened Mexican spotted owl (Strix occidentalis Xántus de Vésey) in the first three years following the fire. Our objective was to explore potential relationships between burn severity and changes in habitat suitability at different spatial scales. To accomplish this, we applied a multi-scale optimized habitat selection model to pre- and post-fire landscapes and compared the differences in predictions along a continuous scale gradient. Fire effects on habitat quality were spatially variable and the strength and direction of relationships were scale-dependent. Spatial patterns of burn-severity mosaic resembled the patterns of habitat suitability change. High burn severity reduced nesting habitat suitability and this relationship was strongest at broad scales. Pre-fire habitat suitability was positively related to burn severity, again at fairly broad scales, but the relationship was weak. Low-severity fires had little effect on habitat suitability. Multi-scale analysis may influence the statistical measures of goodness of fit in assessing fire effects on species and their habitats. Future studies should explicitly address spatial scale when quantifying fire effects.

中文翻译：

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规模在量化火灾对物种栖息地的影响中的作用

近几十年来，美国西部的火灾规模和严重程度有所增加，并且随着气候变暖，预计还会继续增加。许多物种的生境受到大火和高烈度大火的威胁，但是人们对空间尺度对大火和生境改变之间关系的影响知之甚少。我们以2011年Wallow Fire（美国亚利桑那州历史上最大的野火）作为案例研究，评估了濒临灭绝的墨西哥斑点猫头鹰（Strix occidentalisXántusdeVésey）的预计筑巢生境的变化。火。我们的目标是探讨不同空间尺度下烧伤严重程度与栖息地适应性变化之间的潜在关系。为此，我们将多尺度优化栖息地选择模型应用于火灾前和火灾后的景观，并比较了沿连续尺度梯度的预测差异。火灾对栖息地质量的影响在空间上是可变的，并且关系的强度和方向取决于规模。烧伤严重程度马赛克的空间模式类似于生境适应性变化的模式。高烧伤严重程度降低了筑巢栖息地的适应性，这种关系在广泛范围内最强。火灾前生境的适宜性与烧伤严重程度呈正相关，同样在相当大的范围内，但这种关系较弱。低烈度火灾对栖息地的适应性影响很小。在评估火灾对物种及其栖息地的影响时，多尺度分析可能会影响拟合优度的统计度量。