• 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

  • First Soil Ecology Workshop at DMES

    14.06.16
    Event

    Students and scientists of the DMES who are working in the field of soil microbial ecology and biogeochemistry met on May 20th for the first DMES Soil Ecology Workshop. This ...

  • Summer Research Experience @ TER

    19.05.16
    News

    Three positions are available for Masters students during the summer 2016, that will provide a unique opportunity to participate in one of the research projects and become member of the ...

  • MSc. Judith Braun

    26.04.16
    People

    Congratulations!

    Judith Braun successfully defended her Master thesis entitled „Getting to the bottom of 15N Isotope Pool Dilution technique - Gross N Mineralization revisited".
    Excellent, Judith!
     ...

  • Field course in Costa Rica February 2016

    07.03.16
    News

    Wolfgang Wanek, Andreas Richter and Christina Kaiser just returned from a field course in Costa Rica, where they studied soils, plants and ants together with Veronika ...

Latest publications

Soil microbial carbon use efficiency and biomass turnover in a long-term fertilization experiment in a temperate grassland

Soil microbial carbon use efficiency (CUE), defined as the ratio of organic C allocated to growth over organic C taken up, strongly affects soil carbon (C) cycling. Despite the importance of the microbial CUE for the terrestrial C cycle, very little is known about how it is affected by nutrient availability. Therefore, we studied microbial CUE and microbial biomass turnover time in soils of a long-term fertilization experiment in a temperate grassland comprising five treatments (control, PK, NK, NP, NPK). Microbial CUE and the turnover of microbial biomass were determined using a novel substrate-independent method based on incorporation of 18O from labeled water into microbial DNA. Microbial respiration was 28–37% smaller in all three N treatments (NK, NP, and NPK) compared to the control, whereas the PK treatment did not affect microbial respiration. N-fertilization decreased microbial C uptake, while the microbial growth rate was not affected. Microbial CUE ranged between 0.31 and 0.45, and was 1.3- to 1.4-fold higher in the N-fertilized soils than in the control. The turnover time ranged between 80 and 113 days and was not significantly affected by fertilization. Net primary production (NPP) and the abundance of legumes differed strongly across the treatments, and the fungal:bacterial ratio was very low in all treatments. Structural equation modeling revealed that microbial CUE was exclusively controlled by N fertilization and that neither the abundance of legumes (as a proxy for the quality of the organic matter inputs) nor NPP (as a proxy for C inputs) had an effect on microbial CUE. Our results show that N fertilization did not only decrease microbial respiration, but also microbial C uptake, indicating that less C was intracellularly processed in the N fertilized soils. The reason for reduced C uptake and increased CUE in the N-fertilization treatments is likely an inhibition of oxidative enzymes involved in the degradation of aromatic compounds by N in combination with a reduced energy requirement for microbial N acquisition in the fertilized soils. In conclusion, the study shows that N availability can control soil C cycling by affecting microbial CUE, while plant community-mediated changes in organic matter inputs and P and K availability played no important role for C partitioning of the microbial community in this temperate grassland.

Spohn M, Pötsch EM, Eichhorst SA, Woebken D, Wanek W, Richter A
2016 - Soil Biology and Biochemistry, 97: 168-175

Exploring the metabolic potential of microbial communities in ultra-basic, reducing springs at The Cedars, CA, USA: Experimental evidence of microbial methanogenesis and heterotrophic acetogenesis

Present-day serpentinization generates groundwaters with conditions (pH > 11, Eh < −550 mV) favorable for the microbial and abiotic production of organic compounds from inorganic precursors. Elevated concentrations of methane, C2-C6 alkanes, acetate, and formate have been detected at these sites, but the microbial or abiotic origin of these compounds remains unclear. While geochemical data indicate that methane at most sites of present-day serpentinization is abiogenic, the stable carbon, hydrogen, and clumped isotope data as well as the hydrocarbon gas composition from The Cedars, CA, USA, are consistent with a microbial origin for methane. However, there is no direct evidence of methanogenesis at this site of serpentinization. We report on laboratory experiments in which the microbial communities in fluids and sediments from The Cedars were incubated with 13C labeled substrates. Increasing methane concentrations and the incorporation of 13C into methane in live experiments, but not in killed controls, demonstrated that methanogens converted methanol, formate, acetate (methyl group), and bicarbonate to methane. The apparent fractionation between methane and potential substrates (α13CCH4-CO2(g) = 1.059 to 1.105, α13CCH4-acetate = 1.042 to 1.119) indicated that methanogenesis was dominated by the carbonate reduction pathway. Increasing concentrations of volatile organic acid anions indicated microbial acetogenesis. α13CCO2(g)-acetate values (0.999 to 1.000), however, were inconsistent with autotrophic acetogenesis, thus suggesting that acetate was produced through fermentation. This is the first study to show direct evidence of microbial methanogenesis and acetogenesis by the native microbial community at a site of present-day serpentinization.

Kohl L, Cumming E, Cox A, Rietze A, Morrissey L, Lang SQ, Richter A, Suzuki S, Nealson KH, Morrill PL
2016 - Journal of Geophysical Research Biogeosciences, 4: 1203-1220

Plant-derived compounds stimulate the decomposition of organic matter in arctic permafrost soils

Arctic ecosystems are warming rapidly, which is expected to promote soil organic matter (SOM) decomposition. In addition to the direct warming effect, decomposition can also be indirectly stimulated via increased plant productivity and plant-soil C allocation, and this so called “priming effect” might significantly alter the ecosystem C balance. In this study, we provide first mechanistic insights into the susceptibility of SOM decomposition in arctic permafrost soils to priming. By comparing 119 soils from four locations across the Siberian Arctic that cover all horizons of active layer and upper permafrost, we found that an increased availability of plant-derived organic C particularly stimulated decomposition in subsoil horizons where most of the arctic soil carbon is located. Considering the 1,035 Pg of arctic soil carbon, such an additional stimulation of decomposition beyond the direct temperature effect can accelerate net ecosystem C losses, and amplify the positive feedback to global warming.

Wild B, Gentsch N, Capek P, Diakova K, Alves RJ, Barta J, Gittel A, Hugelius G, Knoltsch A, Kuhry P, Lashchinskiy N, Mikutta R, Palmtag J, Schleper C, Schnecker J, Shibistova O, Takriti M, Torsvik VL, Urich T, Watzka M, Santruckova H, Guggenberger G, Richter A
2016 - Scientific Reports, 6: 11

Lecture series

Microbes, nitrogen and plant responses to elevated CO2

César Terrer
Imperial College, London
19.07.2016
11:00 h
Conference room “Ökologie” Althanstr. 14, 1090 Wien

Microbial ecology, phylogeny and biochemistry in the soil cabon cycle

Bruce Hungate, Prof.
Center for Ecosystem Science and Society, Northern Arizona University, USA
22.01.2016
10:30 h
Lecture Hall 4, UZA 2 (Geozentrum), Althanstraße 14,1090 Vienna