Spruce Beetle Outbreak Increases Streamflow From Snow‐Dominated Basins in Southwest Colorado, USA
Spruce Beetle Outbreak Increases Streamflow From Snow‐Dominated Basins in Southwest Colorado, USA
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DOI：
10.1029/2021wr029964
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发表时间：
2022-04
影响因子：
5.4
通讯作者：
Aidan L. Manning;A. Harpold;A. Csank
中科院分区：
文献类型：
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作者：
Aidan L. Manning;A. Harpold;A. Csank
自2000年以来，树皮甲虫已经影响了美国西部超过5800万英亩的针叶林。大多数受甲虫影响的森林都位于积雪为主、水有限的水源盆地，这些盆地产生的水供应比例不成比例。以前的研究表明，树皮甲虫爆发对径流的影响好坏参半，可能会导致流量增加或减少，但这些研究要么早于长期积雪数据，要么基于模型，要么只研究山松甲虫爆发。我们的研究是第一个使用经验的、气候标准化的成对集水区方法来量化对云杉甲虫死亡的径流响应的研究。利用科罗拉多西南部27年的气候和径流观测，我们发现，在六个受甲虫影响的研究流域中，有三个流域在甲虫爆发后的至少三到六年内，年气候标准化径流量增加了22%-37%。受影响流域的流量没有减少，未受影响的控制流域的流量保持不变。在受影响的流域中，没有一个单一的流域特征清楚地解释了径流响应的变化。融雪过程中较高的径流率贡献的任何地方从9%到64%的流量增加，这意味着雪和生长季节的过程中驱动流量增加的重要性。这些研究结果显示变量，有时大量的径流增加，在关键的供水流域后，甲虫杀死亚高山云杉林，和对比的证据不变或减少径流后，甲虫杀死较低海拔的松树林在较冷的北方科罗拉多盆地，突出了气候和森林组成的重要性，在完善水文预测后，山地森林干扰。
Bark beetles have impacted over 58 million acres of coniferous forest in the Western US since 2000. Most beetle impacted forests are in snow dominated, water limited headwater basins, which generate a disproportionate fraction of water supplies. Previous studies show mixed impacts of bark beetle outbreaks on streamflow with the potential to cause increased or decreased flows, but these studies either predate long‐term snowpack data, are model‐based, or examine only mountain pine beetle outbreaks. Ours is the first study to use an empirical, climate‐normalized paired catchment approach to quantify streamflow response to spruce beetle kill. Using 27 years of climate and streamflow observations from southwest Colorado, we show that in three of the six beetle impacted study basins, annual climate‐normalized streamflow increased by 22%–37% for at least three to 6 years after the beetle outbreak. Impacted basins exhibited no decreased flows and flows in unimpacted control basins remained unchanged. Among impacted basins, no single basin characteristic clearly explained variation of streamflow response. Higher runoff ratios during snowmelt contribute anywhere from 9% to 64% of streamflow increases, implying the importance of both snow and growing season processes in driving streamflow increases. These findings show variable, sometimes substantial streamflow increases in critical water supply basins following beetle kill in subalpine spruce forests, and contrast with evidence of unchanged or decreased streamflow following beetle kill in lower elevation pine forests in colder northern Colorado basins, highlighting the importance of climate and forest composition in refining hydrologic predictions following mountain forest disturbances.