TropSOC - Tropical soil organic carbon dynamics along erosional disturbance gradients in relation to variability in soil geochemistry and land use

• Applicant: Professor Dr. Sebastian Dötterl
• Subject Area: Soil Sciences ; Physical Geography
• Term: from 2017 to 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 387472333

The response of soils to disturbance by erosion is one of the great uncertainties in predicting greenhouse gas fluxes from soils to the atmosphere and, hence, future earth system dynamics. This is largely due to a lack of data in remote areas, such as tropical Africa, but also due to an inadequate transfer of knowledge from smaller to larger scales. Tropical Africa is a hotspot of both climate and land use change. The region faces growing population, deforestation of primary forests and degradation of soils due to erosion. Hence, tropical Africa is expected to experience important changes to both soil biogeochemical cycling and ecosystem level carbon (C) fluxes between soil, plants and the atmosphere in this century. In particular, it is unclear how C dynamics differ in the Tropics compared to temperate climate zones, from which most of our mechanistic process understanding on C cycling is derived. It is important to fill this knowledge gap since tropical ecosystems provide services with global importance, such as C storage in plants and soils, soil fertility, plant productivity and ultimately food supply. The main objective of the proposed TROPSOC project is to develop a mechanistic understanding of C sequestration and release in the soils of Tropical Africa, studied in the Eastern part of the Congo Basin. This region provides a unique combination of (i) geologically diverse parent material for soil formation and (ii) different levels of disturbance by human activity, taking place under a humid, tropical climate regime, where pristine forests are converted into agricultural land at high rates. TROPSOC will make a significant contribution to answering the following questions: 1. How will nutrient fluxes and C allocation between soils, plants and the atmosphere evolve and differ in tropical systems in relation to the controlling factors: mineralogy, topography and vegetation? 2. How does geochemistry control, interact with or mediate the severity of erosional disturbance on C cycling in the critical zone of tropical soils? 3. How can we model the mechanisms controlling tropical soil C dynamics in a spatially explicit way? TROPSOC will make a significant contribution to improving our understanding of the factors that give rise to the spatial distribution and fate of C of tropical soil systems. By the end of the project, we will have a better understanding of the factors that give rise to the spatial distribution and fate of carbon in tropical soils. We will have produced benchmark data products and modeling tools that will help to bridge the gap between plot scale process understanding and large scale modeling of tropical C cycling. This will ultimately help to reduce the uncertainty associated with terrestrial C fluxes and the response of soils to disturbance, which is one of the greatest uncertainties in current Earth System Models and ecosystem service assessments.

• DFG Programme: Independent Junior Research Groups