Microbial Engineers – Drivers of Earth Surface Development and Stabilization

• Applicants: Professorin Dr. Ingrid Kögel-Knabner, since 3/2020; Professor Dr. Thomas Scholten
• Subject Area: Physical Geography
• Term: from 2015 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 280511025

Microorganisms play a central role in the development and stabilization of the Earth's surface. They initially fix carbon, nitrogen and their residues and extracellular substances lead to the aggregation of primary soil particles. However, it is largely unclear to what extent microorganisms have a qualitative and quantitative influence on the development of initial soils towards developed soils. Following this question, we assume that a large number of functional groups of microorganisms already exist alongside each other at the beginning of soil formation, whereas a dominant structure of individual groups only emerges during further soil development. In arid areas biocrusts are, in addition to microorganisms, essential elements of habitat development and stabilization of the soil surface. Biocrusts for instance provide very effective protection against erosive rainfall. Under humid climate conditions, plants and their extensive root system form a third central element of soil formation and stabilization, because plants interact with their root system as well as biocrusts very closely with microorganisms.The climate gradient along the Chilean coastal cordillera offers a unique opportunity to analyze the combined effects of microorganisms, biocrusts and plants on soil formation and stabilization. In the second funding phase, we intend to use three combined simulation experiments to investigate how microorganisms alone and together with biocrusts and plants form and stabilize the earth's surface in initial and further developed soils. First, we work in ClimSim with disturbed samples from the dry northern primary study areas (PSAs) of the priority program in the laboratory and simulate wetter climatic conditions with and without microorganisms and add biocrusts and plants. From this we want to learn how parent and soil material would develop under changing climate conditions. In SoilSim we work with undisturbed soil monoliths from all four PSAs. Here we can see how a natural soil reacts under climate change, taking into account vertical flow and interactions between soil horizons. In EroSim we investigate the influence of biocrusts on the stabilization of the surface and thus also on the soil under natural conditions along the climate gradient in all four PSAs. Further, we analyse the combined effect of microorganisms, biocrusts and plant roots for stabilizing the earth's surface by means of rainfall simulation using samples from the lab experiments .In addition to modern microbiological and soil science methods as well as techniques from soil erosion research, the proposed project combines high-resolution imaging and isotope chemical methods from micromorphology and soil science (ESEM-EDX, NanoSIMS). This serves to identify and understand the mechanisms of soil development and stabilization by microorganisms in interaction with soil crusts and plant roots.

• DFG Programme: Priority Programmes
• Subproject of: SPP 1803: EarthShape: Earth Surface Shaping by Biota
• Cooperation Partner: Dr. Steffen Seitz
• Ehemaliger Antragsteller: Professor Dr. Carsten Werner Müller, until 3/2020