• Global Warming:

    the threat of a permafrost Carbon – climate feedback

  • We develop and improve

    stable isotopes techniques for ecological applications

  • Plants, fungi and bacteria interact

    at the root-soil interface

  • Probing the future:

    Climate Change experiments

  • Soil is fundamental to human life

  • Tropical rainforests

    hold the key to global net primary productivity

TER News

Latest publications

Combination of techniques to quantify the distribution of bacteria in their soil microhabitats at different spatial scales

To address a number of issues of great societal concern at the moment, like the sequestration of carbon, information is direly needed about interactions between soil architecture and microbial dynamics. Unfortunately, soils are extremely complex, heterogeneous systems comprising highly variable and dynamic micro-habitats that have significant impacts on the growth and activity of inhabiting microbiota. Data remain scarce on the influence of soil physical parameters characterizing the pore space on the distribution and diversity of bacteria. In this context, the objective of the research described in this article was to develop a method where X-ray microtomography, to characterize the soil architecture, is combined with fluorescence microscopy to visualize and quantify bacterial distributions in resin-impregnated soil sections. The influence of pore geometry (at a resolution of 13.4 μm) on the distribution of Pseudomonas fluorescens was analysed at macro- (5.2 mm × 5.2 mm), meso- (1 mm × 1 mm) and microscales (0.2 mm × 0.2 mm) based on an experimental setup simulating different soil architectures. The cell density of P. fluorescenswas 5.59 x 107(SE 2.6 x 106) cells g−1 soil in 1–2 mm and 5.84 x 107(SE 2.4 x 106) cells g−1 in 2–4 mm size aggregates soil. Solid-pore interfaces influenced bacterial distribution at micro- and macroscale, whereas the effect of soil porosity on bacterial distribution varied according to three observation scales in different soil architectures. The influence of soil porosity on the distribution of bacteria in different soil architectures was observed mainly at the macroscale, relative to micro- and mesoscales. Experimental data suggest that the effect of pore geometry on the distribution of bacteria varied with the spatial scale, thus highlighting the need to consider an “appropriate spatial scale” to understand the factors that regulate the distribution of microbial communities in soils. The results obtained to date also indicate that the proposed method is a significant step towards a full mechanistic understanding of microbial dynamics in structured soils.

Juyal A, Otten W, Falconer R, Hapca S, Schmidt H, Baveye PC, Eickhorst T
2019 - Geoderma, 334: 165-174

Microbial temperature sensitivity and biomass change explain soil carbon loss with warming

Soil microorganisms control carbon losses from soils to the atmosphere, yet their responses to climate warming are often short-lived and unpredictable. Two mechanisms, microbial acclimation and substrate depletion, have been proposed to explain temporary warming effects on soil microbial activity. However, empirical support for either mechanism is unconvincing. Here we used geothermal temperature gradients (>50 years of field warming) and a short-term experiment to show that microbial activity (gross rates of growth, turnover, respiration and carbon uptake) is intrinsically temperature sensitive and does not acclimate to warming (+6 °C) over weeks or decades. Permanently accelerated microbial activity caused carbon loss from soil. However, soil carbon loss was temporary because substrate depletion reduced microbial biomass and constrained the influence of microbes over the ecosystem. A microbial biogeochemical model showed that these observations are reproducible through a modest, but permanent, acceleration in microbial physiology. These findings reveal a mechanism by which intrinsic microbial temperature sensitivity and substrate depletion together dictate warming effects on soil carbon loss via their control over microbial biomass. We thus provide a framework for interpreting the links between temperature, microbial activity and soil carbon loss on timescales relevant to Earth’s climate system.

Walker TWN, Kaiser C, Strasser F, Herbold CW, Leblans NIW, Woebken D, Janssens IA, Sigurdsson BD, Richter A
2018 - Nature Climate Change, 9: in press

A plant–microbe interaction framework explaining nutrient effects on primary production

In most terrestrial ecosystems, plant growth is limited by nitrogen (N) and phosphorus (P). Adding either nutrient to soil usually affects primary production, but their effects can be positive or negative. Here we provide a general stoichiometric framework for interpreting these contrasting effects. First, we identify N and P limitations on plants and soil microorganisms using their respective N to P critical ratios. Second, we use these ratios to show how soil microorganisms mediate the response of primary production to limiting and non-limiting nutrient addition along a wide gradient of soil nutrient availability. Using a meta-analysis of 51 factorial N-P fertilization experiments conducted across multiple ecosystems, we demonstrate that the response of primary production to N and P additions is accurately predicted by our stoichiometric framework. The only pattern that could not be predicted by our original framework suggests that N has not only a structural function in growing organisms, but also a key role in promoting plant and microbial nutrient acquisition. We conclude that this stoichiometric framework offers the most parsimonious way to interpret contrasting and until now unresolved responses of primary production to nutrient addition in terrestrial ecosystems.

Capek P, Manzoni S, Kaštovská E, Wild B, Diakova K, Barta J, Schnecker J, Biasi C, Martikainen P, Alves R, Guggenberger G, Gentsch N, Hugelius G, Palmtag J, Mikutta R, Shibistova O, Urich T, Schleper C, Richter A, Santruckova H
2018 - Nature Ecology & Evolution, 9: 11

Lecture series

When are Mycorrhizas Mutualisms?

Nancy Collins Johnson
Northern Arizona University, USA
22.05.2018
16:15 h
Hörsaal 2 (UZA 1), Althanstraße 14, 1090 Wien

Plant-soil interactions mediating drought effects in grasslands

Pierre Mariotte
Ecole Polytechnique Federale de Lausanne, Switzerland
09.05.2018
16:00 h
Seminar Room Microbial Ecology, Room number 2.309, UZA 1 Althanstr. 14, 1090 Wien

Routing while Scouting: How a Slime Mould Optimizes its Transportation Network during Exploration

DANIEL SCHENZ
Hokkaido University, Japan
24.04.2018
15:00 h
Seminar room DOME, UZA 1, Althanstrasse 14, 1090 Vienna