Anthropogenic influence on rates of aeolian dune activity within the northern European Sand Belt and socio-economic feedbacks over the last ~2500 years
Anthropogenic influence on rates of aeolian dune activity within the northern European Sand Belt and socio-economic feedbacks over the last ~2500 years
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DOI：
10.1177/0959683617715693
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发表时间：
2018-01
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影响因子：
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通讯作者：
Uta Lungershausen;A. Larsen;H. Bork;R. Duttmann
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文献类型：
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作者：
Uta Lungershausen;A. Larsen;H. Bork;R. Duttmann
在欧洲西北部，更新世沙层在全新世森林砍伐和农业土地利用阶段被重新激活。虽然人类活动和沙层活化之间存在时间上的重叠，但风沙活动和社会反应之间的根本原因和随后的反馈在很大程度上仍然未知。在这里，我们试图建立因果关系，通过检查详细的共同变化的时间和规模的风成和人为活动，通过量化的全新世沙丘沉积物结合考古和花粉记录。这些记录表明了一系列复杂的阶段，风成活动之后景观稳定，我们主要归因于不断变化的人类影响模式。我们发现，在中世纪时期沙丘沉积速率的稳步增长对应于定居活动和森林砍伐的增加（~AD 1000-1500）。在其高峰期，中世纪的沉积速率是晚更新世的3.4倍，晚更新世是风成沉积物输送最有利的自然条件。在中世纪时期之前，相对的陆地表面稳定性（以沉积间断为代表）从更新世晚期持续到罗马铁器时代（公元0-400年）。砍伐森林以生产燃料铁对风沙活动的影响很小，记录的最低沉积速率（0.12 ± 0.02吨/公顷/年）表明了这一点。在沉积速率达到中世纪高峰后，风成活动迅速减少，与附近人类定居点的放弃相吻合。这一系列的事件提供了一个直接的正反馈的证据，在中世纪的农业过度开发有利于风成活动，使景观实际上不适合种植农业。根据我们的研究结果和全面审查的北方欧洲沙带活动，我们解释了一个非常高的敏感性，过去和现在的人类影响的风沙活动，并认为，不可持续的土地利用的做法已经广泛的解决放弃的原因。
In North-Western Europe, Pleistocene sand sheets have been reactivated during phases of Holocene deforestation and agricultural land use. Although there are temporal overlaps between anthropogenic activity and sand sheet reactivation, the root cause and subsequent feedbacks between aeolian activity and societal response remain largely unknown. Here, we seek to establish cause and effect by examining the detailed co-variation in both timing and magnitude of aeolian and anthropogenic activity through the quantification of Holocene dune sediments in combination with archaeological and pollen records. These records indicate a series of complex phases of aeolian activity followed by landscape stabilization, which we attribute primarily to changing patterns of human impact. We find that a steady increase in dune deposition rates in the Medieval Period corresponds to an increase in settlement activity and deforestation (~AD 1000–1500). At their peak, Medieval deposition rates were 3.4 times larger than during the late Pleistocene, the period experiencing the most favourable natural conditions for aeolian sediment transport. Prior to the Medieval Period, relative land-surface stability (represented by a depositional hiatus) persisted from the late Pleistocene until the Roman Iron Age Period (AD 0–400). Deforestation to fuel iron production had minor impact on aeolian activity, as indicated by the lowest recorded deposition rate (0.12 ± 0.02 t/ha/a). Following the Medieval Period peak in deposition rates, aeolian activity diminished rapidly and coincided with the abandonment of nearby human settlement. This sequence of events provides evidence of a direct positive feedback in which Medieval agricultural overexploitation favoured aeolian activity that rendered the landscape practically unworkable for cropping agriculture. Based on our findings and a comprehensive review of Northern European sand belt activity, we interpret a very high sensitivity of aeolian activity to past and present human impact and argue that unsustainable land-use practices have been the cause for widespread settlement abandonment.