Sensitivity of Erosion‐Rate in Permafrost Landscapes to Changing Climatic and Environmental Conditions Based on Lake Sediments From Northwestern Alaska
Sensitivity of Erosion‐Rate in Permafrost Landscapes to Changing Climatic and Environmental Conditions Based on Lake Sediments From Northwestern Alaska
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DOI：
10.1029/2022ef002779
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发表时间：
2022-07
期刊：
影响因子：
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通讯作者：
E. Shelef;Melissa P. Griffore;S. Mark;T. Coleman;N. Wondolowski;G. Lasher;M. Abbott
中科院分区：
文献类型：
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作者：
E. Shelef;Melissa P. Griffore;S. Mark;T. Coleman;N. Wondolowski;G. Lasher;M. Abbott
永久冻土下景观的侵蚀可以改变沉积物和养分通量、地表和地下水文、土壤特性以及永久冻土融化率，从而改变高纬度地区的生态系统和碳排放，对全球气候产生潜在影响。然而，未来的侵蚀和沉积物迁移率很难预测，因为它们取决于温度、降水、永久冻土、植被、野火和水文等气候和环境参数之间复杂的相互作用。因此，尽管侵蚀对北极和全球系统的未来具有潜在影响，但侵蚀率与这些参数之间的关系及其相对重要性在很大程度上仍然无法量化。在这里，我们量化这些关系的基础上，从埋葬湖，阿拉斯加，北极湖泊沉积物的最丰富的数据集之一的沉积记录。我们应用一套双变量和多变量技术来探索陆源沉积物流入湖泊（侵蚀速率的代理）和过去25 cal ka BP的古气候和环境条件的各种地球化学沉积代理之间的关联。我们的研究结果表明，侵蚀率与温度和植被代理关系最密切，侵蚀率随着温度的升高，花粉计数以及灌木和树木花粉的丰富度而降低。其他代理，如与火灾频率，风成尘供应，质量浪费和水文条件，发挥次要作用。沉积替代物对侵蚀速率的边际效应通常取决于阈值，突出了侵蚀的强烈非线性变化的潜力，以应对北极条件的未来变化。
Erosion of landscapes underlaid by permafrost can transform sediment and nutrient fluxes, surface and subsurface hydrology, soil properties, and rates of permafrost thaw, thus changing ecosystems and carbon emissions in high latitude regions with potential implications for global climate. However, future rates of erosion and sediment transport are difficult to predict as they depend on complex interactions between climatic and environmental parameters such as temperature, precipitation, permafrost, vegetation, wildfires, and hydrology. Thus, despite the potential influence of erosion on the future of the Arctic and global systems, the relations between erosion‐rate and these parameters, as well as their relative importance, remain largely unquantified. Here we quantify these relations based on a sedimentary record from Burial Lake, Alaska, one of the richest datasets of Arctic lake deposits. We apply a set of bi‐ and multi‐variate techniques to explore the association between the flux of terrigenous sediments into the lake (a proxy for erosion‐rate) and a variety of biogeochemical sedimentary proxies for paleoclimatic and environmental conditions over the past 25 cal ka BP. Our results show that erosion‐rate is most strongly associated with temperature and vegetation proxies, and that erosion‐rate decreases with increased temperature, pollen‐counts, and abundance of pollen from shrubs and trees. Other proxies, such as those associated with fire frequency, aeolian dust supply, mass wasting and hydrologic conditions, play a secondary role. The marginal effects of the sedimentary‐proxies on erosion‐rate are often threshold dependent, highlighting the potential for strong non‐linear changes in erosion in response to future changes in Arctic conditions.