Quantifying Climatic Controls on Sediment Production and Hillslope Evolution

在过去的2-3百万年里，靠近丘陵和山地地形的沉积沉积物记录了沉积物输送的显著变化。这些波动与气候变化有关，但其机制尚不清楚。在这样的景观中，对湖泊沉积物岩心的分析往往揭示了一个复杂的温度和湿度历史，这体现在植被制度的时间格局上。虽然植被对水文过程的影响已经得到了很好的研究，但植被在动员和将土壤输送到河道中的作用还没有得到很好的了解。由于最近的证据表明，生物有机体活动对土壤的混合和破坏可能在土壤的下坡运动中起主导作用，因此山坡的演变可能与生态系统特性的时间变化密切相关。因此，当前的山坡特征反映了一个由气候相关的植被变化调节的复杂历史。PI将量化与气候有关的植被变化对沉积物产生和山坡演变的影响，方法是在具有可变古环境记录的野外地点记录和模拟土壤和自然发生的示踪剂的运输。在我们位于新西兰和美国哥伦比亚高原的黄土覆盖研究地点，我们将使用土壤地层学，高分辨率地形数据和详细的tephra沉积物特征来量化古山坡几何形状并表征土壤运输过程。沿着山坡横断面，他将使用埋藏的麻风沉积物作为记录挖掘的标记床和记录山坡过程如何混合和置换土壤的示踪剂。将土壤、古环境、地形和土壤数据集结合起来，将使他能够测试土壤运输模型，并重建气候变化如何调节晚第四纪的运输速率和山坡动态。PI的结果将有助于新出现的碳封存和运输计算以及土地管理战略。

Joshua J. Roering (EAR-0309975)University of OregonSedimentary deposits proximal to hilly and mountainous terrain record significant variations in sediment delivery over the last 2-3 million years. These fluctuations have been associated with climate change although the responsible mechanisms are poorly known. In such landscapes, analyses of lake-sediment cores often reveal a complex temperature and moisture history as manifested by the temporal pattern of vegetation regimes. While the influence of vegetation on hydrological processes has been well studied, the role of vegetation in the mobilization and transport of soil into channels is not well understood. Because recent evidence suggests that the mixing and disruption of soils by the activity of biological organisms may play a dominant role in the downslope movement of soil, hillslope evolution may be closely tied to temporal changes in ecosystem properties. As a result, current hillslope characteristics reflect a complex history modulated by climate-related changes in vegetation.PI will quantify the influence of climate-related vegetation changes on sediment production and hillslope evolution by documenting and modeling the transport of soil and naturally-occurring tracers in field sites with variable paleo-environmental records. At our loess-mantled study sites in New Zealand and the Columbia Plateau, USA, we will use soil stratigraphy, high-resolution topographic data, and detailed characterizations of tephra deposits to quantify paleo-hillslope geometry and characterize soil transport processes. Along hillslope transects, he will use buried tephra deposits as both a marker bed for recording exhumation and a tracer for documenting how hillslope processes mix and displace soil. When combined, soil, paleo-environmental, topographic, and tephra datasets will enable him to test soil transport models and reconstruct how climate change regulated transport rates and hillslope dynamics in the late Quaternary. PI's results will be useful for newly emerging carbon sequestration and transport calculations as well as land management strategies.