Soil microorganisms and plants are key players in the production and breakdown of organic matter, and together control global biogeochemical cycles of carbon, nitrogen and phosphorus. TER, the Division of Terrestrial Ecosystem Research, aims to advance our fundamental understanding of how plants and soil microorganisms respond to, and in turn shape, their abiotic and biotic environment, and to determine the consequences for the functioning of Earth’s ecosystems.

Research Mission

Primarily dedicated to basic research, TER addresses pressing environmental issues, such as the impact of climate and land-use change on ecosystem functioning and the role of soils in the global carbon cycle and in food security. In doing so, we work on scales from µm (i.e. the scale at which microbes operate) to the biosphere (i.e. where plant and microbial processes become evident), and in ecosystems spanning the Arctic tundra to tropical rainforests. We integrate this scale of thinking with state-of-the-art methods, including stable isotope tracing and biomarker fingerprinting, and are developing novel approaches to estimate gross environmental processes with isotope pool dilution techniques.

We are strongly committed to conduct world-leading research in a motivating and intellectually stimulating environment, and to train our students to become independent and internationally competitive scientists who enjoy research and contribute to society as conscientious citizens.

Uni Wien/Der Knopfdruecker

Research Projects

SPACE - The spatial aspect of rhizosphere priming

Current Projects TER | Christina Kaiser

Higher plants release a significant proportion of the carbon (C) they assimilate into the rhizosphere – mainly as sugars, amino acids or organic acids.

Pixabay / Jerzy Gorecki

This labile carbon has been shown to substantially accelerate microbial decomposition of ‘old’ or ‘recalcitrant’ soil organic matter and thus facilitate the release of CO2 to the atmosphere in a phenomenon called the “rhizosphere priming effect” (RPE). Despite the high potential of rhizosphere priming to influence global C cycling, its underlying mechanisms are still under debate, leading to high uncertainties in the predictions of future net C flux between soil and atmosphere.

We propose that microscale spatial interactions between microbes and their environment are essential for understanding RPEs, as biological (such as microbial decomposition) and physico-chemical processes (such as micro- and macroaggregate turnover) are linked at the microscale. The goal of this project is to ‘zoom in’ and investigate the RPE at the scale microorganisms operate. By analyzing how interactions between microbes and their microenvironment are linked to emerging C and N dynamics we aim to develop a unifying concept of rhizosphere priming in soil.

We will approach this goal by a combined experimental and modelling approach. We will prepare ‘experimental soils’ with plant-derived particulate organic matter (POM) encapsulated in macroaggregates and employ a novel ‘reverse microdialysis’ technique which will allow us to introduce a defined solution of labile substrate via microdiffusion into the soil, mimicking root exudations. Using state-of-the-art stable-isotope methods we will follow the fate of (i) 13C15N-labelled labile substrates, (ii) 13C15N-labelled POM, and (iii) native (unlabeled) SOM concomitantly through living and dead organic matter pools (f.e. PLFAs and microbial necromass) and trace microbial community composition (16S rRNA and ITS amplicon sequencing) and processes across the soil aggregate hierarchy at small spatial scales. In an additional experiment, we will investigate how the interaction between mycorrhizal roots and soil microarchitecture affects the RPE after 13CO2 pulse-labelling of young beech trees. We will further research into the µm-scale spatial dynamics of microbes in intact soil aggregates after labile substrate input with a joint fluorescence-in-situ-hybridisation (FISH) and nanoscale secondary ion mass spectrometry (NanoSIMS) analysis, a novel combination for the analysis of undisturbed soil cores. In a complementary theoretical modelling analysis, we will investigate possible ‘emergent’ phenomena (such as self-organisation or self-regulation) triggered by microbial microscale interactions in a spatially explicit and dynamic microenvironment, by expanding an existing individual-based computer model.

Funded by the FWF - Austrian Science Fund, Project Nr P 30339.

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