Carbon drivers and microbial agents of soil respiration
The aim of this project is to elucidate the link between soil respiration, via its microbial agents, and the carbon (C) compounds derived from the soil organic matter (SOM) that are respired. To achieve this, I first aspire to identify the carbon (C) compounds of the SOM that primarily contribute to respiration and subsequently investigate which microbial groups that dominate this process. This will be accomplished through four parallel research efforts:
- the principal soluble molecular components of the soil organic matter (dissolved organic C, DOC) will be extracted, identified and quantified.
- the contribution to respiration of the identified C components from (1) will be determined via the14C signal. This will be accomplished through “spiking” radiolabelled (14C) tracers into the identified DOC components in a factorial design, and reintroduce this as intact soil extract into soil samples.
- to elucidate the microbial groups responsible for the respiration (from (2)), mass-isotope (13C) labelled components from the DOC will be “spiked” into the identified (from (1)) DOC components in a factorial design, followed by reintroduction of the extract into soil samples. Subsequently, phospholipid fatty acid markers of the microbial community will be analysed for 13C-enrichment using GC / MS analyses.
- the experimental aspects (2) and (3) will be investigated in laboratory conditions as well as in in situ field conditions.