[Enviro-lunch] Today 9/27: Dr. Jörg Schnecker

[Jing Yan]

[Inline image 1]
Hello Everyone,
Please join us for a talk Today. Sept. 27 by Dr. Jörg Schnecker, 12-1pm in Room SE2-302.


Talk Title:
Seasonal dynamics of soil microbial carbon sequestration

[cid:image002.jpg at 01D45647.CB133F50]

Abstract:
Rising CO2 concentrations in the atmosphere call for efficient mitigation strategies, such as sequestration of C into persistent soil organic matter (SOM). Since the majority of SOM is microbially derived, a first step is the efficient uptake of C inputs by soil microbes. Microbes attribute incorporated C either into growth or respiration to gain energy. Efficient uptake or high carbon use efficiency (CUE) is a high attribution of C towards microbial growth with little loss of CO2 via microbial respiration.
Microbial CUE strongly depends on substrate quality, availability of N and environmental factors such as temperature and moisture. As all of these factors change seasonally, CUE might vary over the course of a year and create times of high and low CUE and in turn times of high and low ability of soil microbes to sequester carbon.
To address the question of seasonal variability of microbial CUE, we ran the soil C model MIMICS with seasonally different drivers (temperature, inputs of easily available C, uptake of nitrogen (N) and litter fall input). We created seasonal patterns for these factors, based on literature and existing model simulations for a deciduous hardwood forest. We used a base version of MIMICS with constant (non-seasonally-variable) temperature, evenly distributed input of easily available C, leaf litter and loss of N out of the system (simulating plant N uptake). We then manipulated each of these factors individually to better reflect seasonal dynamics in situ. Temperature was adjusted to follow a bell-shaped curve over the course of a year, with lows of -5°C in winter to highs of 20°C in summer. Input of easily available C (simulating root exudation) and N loss followed a similarly shaped curve with highs in summer and lows in winter. The input of leaf litter was realized as a single event in fall. In a final simulation, all individually adjusted factors were combined. Preliminary results showed that seasonal changes of easily available C inputs and N loss had little effect on CUE. Litter fall had a negative effect on CUE in fall.
Currently we test our modelling results in a deciduous forest in which we established litter removal plots and in an agricultural field with and without crop residue incorporation. We are sampling these plots and corresponding control plots with litter/crop residue input bi-monthly and measure CUE along with measurements of soil organic matter and microbial parameters.
Our preliminary results show that CUE might vary seasonally. In respect to C sequestration in soils, this could indicate that there are high and low times for soil microbes to efficiently build stable soil organic matter.

Bio:
Jörg Schnecker received his PhD at the Department of Microbiology and Ecosystem research at the University of Vienna. His PhD work investigated decomposition processes in arctic permafrost soils in Siberia. After working on a long-term soil warming experiment in the Austrian Alps, her transitioned into research on microbial decomposition in agricultural soils during a Postdoc at the University of New Hampshire. Jörg Schnecker is now back at the University of Vienna, where his research is focussed on the role of microbial physiology in soil organic matter formation.

When: Sept. 27, Thursday, 12pm - 1pm

Where: SE2-302

Coffee will be provided, please bring your own mugs.

We look forward to seeing you,

Nate & Jing

Organizers for Fall 2018: Nate Bogie and Jing Yan
Faculty coordinator: Asmeret Asefaw Berhe


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