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首页> 外文期刊>Journal of Geophysical Research. Biogeosciences >Linkages Among Climate, Fire, and Thermoerosion in Alaskan Tundra Over the Past Three Millennia
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Linkages Among Climate, Fire, and Thermoerosion in Alaskan Tundra Over the Past Three Millennia

机译：在过去的三千年中，阿拉斯加苔原的气候，火灾和热菌之间的联系

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Amplified Arctic warming may facilitate novel tundra disturbance regimes, as suggested by recent increases in the rate and extent of thermoerosion and fires in some tundra areas. Thermoerosion and wildfire can exacerbate warming by releasing large permafrost carbon stocks, and interactions between disturbance regimes can lead to complex ecosystem feedbacks. We conducted geochemical and charcoal analyses of lake sediments from an Alaskan lake to identify thermoerosion and fire events over the past 3,000 years. Thermoerosion was inferred from lake sediments in the context of modern soil data from retrogressive thaw slumps (RTS). Magnetic susceptibility (MS), Ca:K, and Ca:Sr increased with depth in modern RTS soils and were higher on recently exposed than older slump surfaces. Peaks in bulk density, % CaCO3, Ca: K, Ca:Sr, and MS values in the sediments suggest at least 18 thermoerosion events in the Loon Lake watershed over the past 3,000 years. Charcoal analysis identifies 22 fires over the same period at this site. Temporal variability in these records suggests climate-driven responses of both thermoerosion and fire disturbance regimes, with fewer RTS episodes and fire events during the Little Ice Age than the Medieval Climate Anomaly. Moreover, RTS activity lagged behind catchment fires by 20-30 years (>90% confidence interval), implying that fires facilitated thermoerosion on decadal time scales, possibly because of prolonged active-layer deepening following fire and postfire proliferation of insulative shrub cover. These results highlight the potential for complex interactions between climate, vegetation, and tundra disturbance in response to ongoing warming.
机译：扩增的北极变暖可以促进新的苔原障碍制度，如近期在一些苔原地区的热腐蚀和火灾的速度和程度增加的增加。通过释放大型永久冻土碳储备，热腐蚀和野火可以加剧变暖，干扰制度之间的相互作用会导致复杂的生态系统反馈。我们开展了从阿拉斯加湖苏醒沉积物的地球化学和木炭分析，以识别过去3000年的热腐蚀和火灾事件。从倒退的解冻坍塌（RTS）的现代土壤数据的背景下从湖泊沉积物中推断出热腐蚀。磁敏感性（MS），CA：K和CA：Sr在现代RTS土壤中增加了深度，最近暴露于较旧的坍落度表面。沉积物中的峰值，％CaCO3，Ca：K，Ca：Sr和MS值和MS值在过去3000年里，Loon Lake Shatershed中，至少有18个热腐蚀活动。木炭分析在该网站的同一时期内识别22场火灾。这些记录中的时间变异性表明了气候驱动的反应，热腐蚀和消防干扰制度，较少的RTS发作和火灾事件比中世纪气候异常的较少。此外，RTS活性落后于集水区射击20-30岁（> 90％的置信区间），暗示促进了截止额外时间尺度的热渗滤，可能是由于在火灾之后深化和绝缘灌木覆盖的推动率的延长的有源层。这些结果突出了气候，植被和苔原干扰之间复杂相互作用的潜力，以应对持续变暖。

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