Collaborative Research: Climatic and biotic controls on Late Quaternary erosion in the Oregon Coast Range

合作研究：俄勒冈海岸山脉晚第四纪侵蚀的气候和生物控制

• 批准号: 0952186
• 负责人: Joshua Roering
• 金额: $ 32.45万
• 依托单位: University of Oregon Eugene
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-04-15 至 2014-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0952186&HistoricalAwards=false
• 关键词: Collaborative; Research; Climatic; biotic; controls

Geomorphic processes that sculpt landscapes and constitute natural hazards vary with climatic fluctuations that have characterized the last several million years of Earth history. While some climate-driven erosional processes, such as glaciers, leave a profound topographic imprint, others are more difficult to decipher. Changes in vegetation, for example, should affect the frequency and magnitude of landslides and the vigor of soil production and transport on hillslopes, yet there is sparse information regarding landscape response to late Quaternary variations in vegetation. By coupling records of paleo-erosion and paleo-ecology from a landslide-dammed lake in the Oregon Coast Range, this research will document how late Quaternary vegetation changes translated into landscape modification. The study will extend and augment a previously published paleoenvironmental record showing that the structure and composition of forests in the study area have changed dramatically over the last 40,000+ years. By analyzing paleo-erosion rates using cosmogenic radionuclides from additional lake sediment cores, the study will determine whether increases in the density and size of trees tend to increase or decrease rates of sediment transport and erosion. Although trees and understory vegetation are important for anchoring soil and suppressing erosion over human timescales, bioturbation is thought to be a major driver of landscape change when integrated through time. As such, the net geomorphic effect of a change from meadow-dominated, parkland forests to closed, coniferous forests is difficult to predict with the current knowledge base. The project results will address first-order linkages between climate and geomorphic processes and test emerging numerical models that assess how landscapes evolve in response to millenial-scale climate and vegetation changes.The research project seeks to document and quantify how changes in climate and vegetation over the last 40,000 years have affected rates of erosion in a steep, forested landscape. The anticipated outcomes are important for predicting how future climate change will influence landscape dynamics as well as interpreting human-induced changes, such as those associated with timber harvesting. Although numerous numerical models exist to predict landscape adjustment to climate change, the governing equations are poorly understood and in particular, the role of vegetation requires significant quantitative advancement. By exploiting a detailed sedimentary record preserved in a lake from a mountainous environment, the results will reveal how ecosystems and landscapes may have co-evolved to generate the current terrain. The results should also reveal whether 'events' or periods of rapid surface change have occurred in recent geological history in response to climate or vegetation change.

雕刻景观和构成自然危害的地貌过程因气候波动而变化，其特征是地球历史的最后几百万年。 尽管某些气候驱动的侵蚀过程（例如冰川）留下深刻的地形印记，而另一些则更难破译。 例如，植被的变化应影响山体滑坡的频率和幅度，以及在山坡上的土壤生产和运输的活力，但是关于景观对植被晚期变化的景观响应的信息很少。 通过从俄勒冈海岸山脉的山体 - 压缩湖泊中的古浸润和古生物学的耦合记录，这项研究将记录第四纪植被变化的晚期变化，转化为景观修饰。 这项研究将扩展和增强先前发表的古环境记录，表明在过去40,000多年中，研究区域中森林的结构和组成发生了巨大变化。 通过使用来自其他湖泊沉积物核心的宇宙基因放射性核素分析古渗透率，该研究将确定树木的密度和大小的增加是否倾向于增加或降低沉积物传输和侵蚀的速率。 尽管树木和林木植被对于锚定土壤和抑制人类时标的侵蚀至关重要，但随着时间的推移整合，生物扰动被认为是景观变化的主要驱动力。 因此，通过目前的知识库，很难预测从草地主导的帕克兰森林变成封闭的针叶林的变化的净地貌效应。 该项目的结果将解决气候与地貌过程之间的一阶连接，并测试新兴的数值模型，以评估景观如何响应千年尺度的气候和植被的变化。该研究项目旨在记录和量化过去40,000年的气候和植被的变化如何影响陡峭的森林景观景观的侵蚀率。 预期的结果对于预测未来的气候变化将如何影响景观动态以及解释人类诱发的变化，例如与木材收获相关的变化。 尽管存在许多数值模型来预测对气候变化的景观调整，但理解方程知之甚少，尤其是，植被的作用需要显着的定量进步。 通过利用从山区环境中保存在湖中的详细沉积记录，结果将揭示生态系统和景观如何共同发展以产生当前的地形。 结果还应揭示响应气候或植被变化的近期地质历史中“事件”或快速表面变化的时期。