How will climate change affect wildland fire severity in the western US?
How will climate change affect wildland fire severity in the western US?
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气候变化将如何影响美国西部荒地火灾的严重程度？
DOI：
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发表时间：
2016
期刊：
影响因子：
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通讯作者：
W. C. Richards
中科院分区：
文献类型：
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作者：
S. Takai;W. C. Richards
由于人为气候变化，预计北美的火势特征将在未来几十年内发生变化。尽管在气候变化的背景下，一些火灾特征（例如，燃烧面积和火灾季节长度）得到了相对充分的研究，但火灾严重程度受到的关注较少。在这项研究中，我们使用 1984 年至 2012 年美国西部 (US) 的观测数据建立了一个火灾严重程度随气候变化的统计模型。然后，我们将该模型应用于代表 RCP 8.5 情景下的本世纪中叶（2040-2069）条件的几个（n = 20）气候变化预测。模型预测表明美国西部大部分地区的火灾严重程度普遍降低。然而，我们的模型隐含地纳入了气候引起的植被类型、燃料负荷和火灾频率的变化。因此，我们的预测最好被解释为火灾严重程度可能会降低，但由于人类引起的植物群落和气候之间的不平衡，这种潜力可能无法实现。因此，为了实现本研究中预测的火灾严重程度的降低，美国西部的土地管理者可以通过主动恢复处理（例如机械间伐和规定火灾）和被动恢复策略（例如管理自然火灾（在适当的天气条件下））等手段，促进植物群落向与新兴气候保持平衡的状态过渡。通过积极的灭火等活动来抵制植被成分和燃料负荷的变化，将加剧不平衡条件，并可能导致未来几十年火灾严重程度的增加，因为燃料负荷将随着气候变暖而增加，火灾危险变得更加极端。我们的研究结果提供了在气候变化的背景下抵制或促进植被组成和燃料负荷变化的利弊的见解。
Fire regime characteristics in North America are expected to change over the next several decades as a result of anthropogenic climate change. Although some fire regime characteristics (e.g., area burned and fire season length) are relatively well-studied in the context of a changing climate, fire severity has received less attention. In this study, we used observed data from 1984 to 2012 for the western United States (US) to build a statistical model of fire severity as a function of climate. We then applied this model to several (n = 20) climate change projections representing mid-century (2040–2069) conditions under the RCP 8.5 scenario. Model predictions suggest widespread reduction in fire severity for large portions of the western US. However, our model implicitly incorporates climate-induced changes in vegetation type, fuel load, and fire frequency. As such, our predictions are best interpreted as a potential reduction in fire severity, a potential that may not be realized due human-induced disequilibrium between plant communities and climate. Consequently, to realize the reductions in fire severity predicted in this study, land managers in the western US could facilitate the transition of plant communities towards a state of equilibrium with the emerging climate through means such as active restoration treatments (e.g., mechanical thinning and prescribed fire) and passive restoration strategies like managed natural fire (under suitable weather conditions). Resisting changes in vegetation composition and fuel load via activities such as aggressive fire suppression will amplify disequilibrium conditions and will likely result in increased fire severity in future decades because fuel loads will increase as the climate warms and fire danger becomes more extreme. The results of our study provide insights to the pros and cons of resisting or facilitating change in vegetation composition and fuel load in the context of a changing climate.