Microbiological stabilization of the Earth‘s surface across a climate gradient

 

Investigator Names and Contact Info:

• Dirk Wagner (Microbiology). German Research Centre for GeoSciences (GFZ) Potsdam, Germany
• Thomas Scholten (Soil Science/Geomorphology). University of Tuebingen, Germany
• Peter Kühn (Soil Science/Geomorphology). University of Tuebingen, Germany
• Carsten W. Mueller (Soil Science). Technische Universität München, Germany
• Steffen Seitz (Soil Science/Geomorphology). University of Tuebingen, Germany
• Karsten Schmidt (Soil Science/Geomorphology). University of Tuebingen, Germany

 

Chilean Collaborators Involved:

• Rómulo Oses (Microbial Ecology / Environmental Microbiology). Center of Advanced Studies in Arid Zones (CEAZA) & CRIDESAT - University of Atacama
• Oscar Seguel. Department of Engineering and Soil Science, Faculty of Agronomy, University of Chile,  Santiago, Chile

 

 

Project 13a:

Understanding of microbial communities and the impact of their metabolic processes on the development of a soil stabilizing structure in Chilean soil ecosystems under different climate conditions.

 

PhD-Student:

• Lisa-M. Moskwa. GFZ, Potsdam, Germany

Supervisor: Prof. Dirk Wagner

 

Project 13b:

Understanding of microbial-mediated soil structure formation processes and pedogenesis and how they are interrelated to soil erosion processes in Chilean soil ecosystems under different climate conditions.

 

PhD-Student:

• Nadine Bernhard. University of Tuebingen, Germany

Supervisor: Prof. Thomas Scholten, Co-supervisor: Dr. Peter Kühn

 

Untersuchung der klimatischen Einflüsse auf die Aggregatbildung und mikrobiologische Aktivität in Böden.

 

MSc-Student:

• Juliana Klein. University of Tuebingen, Germany

Supervisor: Prof. Thomas Scholten, Co-supervisor: Dr. Peter Kühn

 

Initial soil erosion as a fuction of aggregate stability at different slope positions under different climates in Chile.

 

MSc-Student:

• Johanna Kinkela. University of Tübingen, Germany

Supervisor: Dr. Steffen Seitz, Co-supervisor: Prof. Thomas Scholten

 

Project Summary:

Most of Earth is covered by soils and sediments. In this upper layer processes of decomposition of organic matter and structure formation are mediated by microorganisms. In this context, MICSTAB asks how and to which extend microorganisms control the stabilization and formation of Earth’s surface. We hypothesize that the mechanisms of stabilization by microorganisms occur under all climate conditions but with varying intensity and different microbiological community structure in the presence of different types of vegetation providing energy to the microorganisms. Further, we assume that initial pedogenesis following soil erosion, i.e. structure formation differs in intensity and microbial community structure between erosional and depositional sites and that related process intensities are controlled by climate. To address these questions, we conduct research in three primary study areas along a climate gradient from north to south in Chile. In each area, typical topographic positions, such as (i) geomorphodynamic stable reference site on hill top with no erosion or deposition, (ii) eroded site at the upper slopes, and (iii) depositional site at toe slopes, will be used for an in-field rainfall simulation experiment and a laboratory soil structure simulation experiment. We use rainfall simulation under natural conditions to analyze the erosion resistance of the land surface as a self-regulatory process after hundreds to thousands of years of soil formation under equilibrium conditions. The soil structure simulation experiment applies wet/dry cycles to samples from all climate regions and topographic positions to highlight soil structure formation with and without microorganism as a crucial part of surface stabilization processes. Both experiments are designed to better understand i) how microbiological processes control soil structure formation and stabilize Earth’s surface, ii) how microbial-mediated soil structure formation is influenced by redistribution of solid material and iii) how microbial communities react to changes in soil erosionunder different climate conditions. High resolution imaging techniques such as epifluorescence microscopy, SEM-EDX, confocal laser scanning microscopy and NanoSIMS can help to understand better the interrelationship of microorganisms and soil structure formation. These cutting-edge technologies, combined with integrated stable isotope techniques (e.g stable isotope probing, SIP) and state-of-the-art molecular ecological, soil chemical analyses as well as modern techniques of soil erosion research, will serve to identify and understand microbial-mediated key processes of land surface stabilization.