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

地表的演化受1)物理和化学风化作用，2)山坡和河道侵蚀作用，3)沉积物的搬运和沉积作用的支配。生物群，尤其是植被，在这三个过程中起着至关重要的作用，并反过来受到这些过程的影响。根据时间尺度的不同，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，沉积物沉积特别重要，因为它产生了高生产力的栖息地，从而促进了新植被的建立，从而改变了地球表面的过程。因此，了解地表对不同时间尺度环境变化的响应需要对地表过程和植被动态之间的相互作用有详细的了解。本项目旨在了解沿智利气候梯度的四个重点流域的生物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性质，以及沿水流路径的地貌动力学。该研究结合了来自植被地理学、地貌测绘、高分辨率地形调查、流域出口沉积物监测以及基于gis的沉积物连通性模型和泥沙通量数值模型（使用Erosion3D）的数据。这些信息将用于在地貌模型中实现植被动态的模式表示，并汇编四个重点流域的当代沉积物预算。结合EarthShape项目的第一阶段，重点关注长期沉积物储存库存和预算，我们能够区分植被模式对沉积物保留和连通性的直接（短期）影响，以及植被调节的风化和运输的长期地形影响。总之，该项目将通过地貌学和生物地理学技术的结合，加深我们对变化的生物地貌反馈和生物地貌系统对外部驱动因素的非线性响应的理解。

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.