Biogeomorphic feedbacks and their role for sediment erosion and connectivity along a climatic gradient in Chile

地球表面的演变受i）物理和化学风化，ii）山坡和河道侵蚀，以及iii）沉积物的运输和沉积控制。生物区系和最主要的植被在所有这三个过程中起着至关重要的作用，反过来又受到这些过程的影响。根据时间尺度，生物群可以增加或减少地球表面过程的速率。在植物作为生态系统工程师的背景下，沉积物沉积具有特别重要的意义，因为它产生高生产力的栖息地，从而促进新植被的建立，这反过来又改变了地球表面的过程。因此，要了解不同时间尺度下地球表面对环境变化的反应，就需要对地球表面过程和植被动态之间的相互作用有详细的了解，本项目旨在了解智利气候梯度沿着四个重点流域的植被地貌反馈及其对沉积物动态的影响。我们将研究植被和土壤特性，以及沿着水流路径的地貌动态。该研究综合了植被地理、地貌制图、高分辨率地形测量、集水区出口沉积物监测、基于地理信息系统的沉积物连通性建模和沉积物通量数值建模（使用Erosion3D）等方面的数据。这些信息将用于实现地貌模型中植被动态的模式表示，并编制四个重点流域的当代沉积物预算。结合EarthShape项目的第一阶段，重点是长期沉积物储存清单和预算，我们能够区分植被模式对沉积物保留和连接的直接（短期）影响，以及植被介导的风化和运输的长期地形影响。总之，拟议的项目将加深我们的理解不断变化的地貌反馈和非线性响应的地貌系统外部驱动器通过地貌和地理技术相结合。

The evolution of the earth surface is governed by i) physical and chemical weathering, ii) hillslope and channel erosion, and iii) transport and deposition of sediment. Biota, and most prominent vegetation, plays a crucial role in all three processes and in turn is effected by these processes. Depending on the timescale, biota can increase or decrease the rates of earth surface processes. In the context of plants as ecosystem engineers, sediment deposition is of special importance since it generates high productivity habitats and thus facilitates the establishment of new vegetation, which in turn modifies earth surface processes. Understanding the response of the earth surface to environmental changes at various time scales thus requires a detailed knowledge on the interaction between earth surface processes and vegetation dynamics.This project aims to understand biogeomorphological feedbacks and how they affect sediment dynamics in the four focus catchments along the climate gradient of Chile. We will study vegetation and soil properties, and geomorphic dynamics along the flow path of water. The study combines data from vegetation geography, geomorphological mapping, high resolution topographic surveys, sediment monitoring at the outlet of the catchments and the GIS-based modelling of sediment connectivity and the numerical sediment flux modelling (using Erosion3D). This information will be used to achieve a patter representation of vegetation dynamics in geomorphic models and to compile contemporary sediments budgets of the four focus catchments. In conjunction with the first phase of this project in EarthShape, which focuses on long-term sediment storage inventory and budgets, we are able to differentiate the direct (short-term) effects of the vegetation patterns on sediment retention and connectivity from long-term topographic effects of vegetation mediated weathering and transport. In summary, the proposed project will deepen our understanding of the changing biogeomorphic feedbacks and the non-linear responses of biogeomorphic systems to external drivers through a combination of geomorphological and biogeographical techniques.