EarthShape

Earth Surface Shaping by Biota. A German-Chilean Research Initiative

The overarching research question of this project is how microorganisms, animals, and plants influence the shape and development of the Earth’s surface over time scales from the present-day to the distant geologic past. EarthShape bridges between scientific disciplines and includes geoscientists and biologists to study this complex question from different viewpoints. Approximately 60 German and 20 Chilean researchers are involved in a diverse range of projects of this priority program.

All study sites are located in the north-to-south trending Coastal Cordillera mountains of Chile, South America. These sites span from the Atacama Desert in the north to the Araucaria forests approximately 1300 km to the south. The site selection contains a large ecological and climate gradient ranging from very dry to humid climate conditions. The sites were selected to avoid other complicating factors such as differences in rock type, and glacial, and volcanic impacts. EarthShape is a 6-year priority program that started in 2016 and is funded through the German Science Foundation (DFG-SPP 1803).

The working group is involved in two geomorphological sub-projects:

Phase I, Project 4: “BioScapes IV: Biotic effects on sediment storage and connectivity in river catchments across timescales.” (completed)

Phase II, Project 6: “Biogeomorphic feedbacks and their role for sediment erosion and connectivity along a climatic gradient in Chile” (ongoing)

Phase II is a continuation of the work conducted in EarthShape phase I, where we quantified how climate and vegetation affected the long-term geomorphic conditions of four study areas along the Coastal Cordillera. Therefore, we focused on source to sink sediment connectivity along the flow path of water and sediment in river catchments. We state that biotic effects on sediment routing are scale dependent: on short (biotic) time scales, vegetation disconnects flow path, while on long (geologic) time scales vegetation increases connectivity through biotic weathering. The second field phase involves:

1. Improving the representation of vegetation in sediment transport modelling through vegetation surveys, mapping and assessment of the 3D vegetation structure.

2. Quantifying contemporary sediment dynamics (erosion and deposition) at selected sites in the EarthShape catchments, using repeated drone surveys and structure from motion photogrammetry

3. Modelling contemporary and catchment-integrated sediment budgets of the four ES-sites and quantify biotic influences on hillslope erosion and sediment deposition using the model Erosion3D at the catchment.

4. Finalizing work from the first phase and derive long-term sediment budgets

5. Identifying and comparing biogeomorphic feedbacks along a climatic gradient at short and long timescales and integrating results using hierarchical biogeomorphic concepts