Abstract We used Landsat-based measures of annual evapotranspiration (ET) to explore the effects of wildfires on vegetation water use across California’s Sierra Nevada. Wildfires decreased ET relative to unburned and pre-fire controls, in many areas this reduction persisted for at least 15 years. The ET reduction averaged 265 mm yr−1 (36% of pre-fire ET) during the first year after fire, and 169 mm yr−1 (23%) over the first 15 years after fire. The ET reduction varied with burn severity, pre-fire canopy density, and hydro-topographic environment. In areas burned at low severity the ET reduction in the first year after fire averaged 224 mm yr−1 (31% of pre-fire ET) whereas high severity were reduced a 362 mm yr−1 (50%) for the first year. Forest stands that were denser pre-fire had a larger ET reduction across all burn severities. Evapotranspiration reduction following moderate-to-high-severity burns was greatest at 900–1300 m asl elevation. The combination of pre-fire canopy density and burn severity explained 70% of the spatial variation in first-year ET reduction. Forest restoration and a reintroduction of low-intensity fire have been proposed as management practices to mitigate fire risk and improve ecosystem health. Our findings illustrate that restoration and fire reintroduction may reduce the current total ET by up to 9%, with potential benefits for downstream water supply in a globally important food-producing region.

中文翻译：

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加州内华达山脉蒸发蒸腾的野火控制

摘要 我们使用基于 Landsat 的年度蒸散量 (ET) 测量来探索野火对加利福尼亚内华达山脉植被用水的影响。与未燃烧和火灾前控制相比，野火减少了 ET，在许多地区，这种减少持续了至少 15 年。火灾发生后的第一年，ET 平均减少 265 mm yr−1（火灾前 ET 的 36%），火灾后的前 15 年平均减少 169 mm yr−1（23%）。ET 减少因燃烧严重程度、火灾前树冠密度和水文地形环境而异。在低严重程度燃烧的区域，火灾后第一年的 ET 平均减少 224 mm yr-1（火灾前 ET 的 31%），而高严重程度的第一年减少了 362 mm yr-1（50%）。火灾前密度更大的林分在所有燃烧严重程度中的 ET 减少幅度更大。在 900-1300 m asl 海拔处，中度至高度烧伤后的蒸散量减少最大。火灾前冠层密度和烧伤严重程度的结合解释了第一年 ET 减少的 70% 的空间变化。森林恢复和重新引入低强度火灾已被提议作为减轻火灾风险和改善生态系统健康的管理实践。我们的研究结果表明，恢复和重新引入火灾可能会将当前的总 ET 减少多达 9%，这对全球重要的粮食产区的下游供水具有潜在的好处。森林恢复和重新引入低强度火灾已被提议作为减轻火灾风险和改善生态系统健康的管理实践。我们的研究结果表明，恢复和重新引入火灾可能会将当前的总 ET 减少多达 9%，这对全球重要的粮食产区的下游供水具有潜在的好处。森林恢复和重新引入低强度火灾已被提议作为减轻火灾风险和改善生态系统健康的管理实践。我们的研究结果表明，恢复和重新引入火灾可能会将当前的总 ET 减少多达 9%，这对全球重要的粮食产区的下游供水具有潜在的好处。