Microbial controls on biogeochemical cycling of carbon using stable isotope labeling and other novel techniques
Abstract
In this session, I will present on ecosystem responses from the molecular and microbial to atmospheric scale, using stable isotope labeling. Predicted increases in temperatures in Northern peatlands are expected to drive substantial alterations to global carbon (C) cycling. In many peatlands, increased temperatures will drive the decomposition of ancient recalcitrant C pools, as well as a surge of new potentially labile C fluxes, as highly productive plant communities (e.g., sedges) take over these systems. The result will be a large increase in microbial decomposition of ancient C and emissions of the greenhouse gases CO2 and CH4. Much attention and study has focused on the fate of old C, which may decompose as temperatures increase, but the fate of new C inputs resulting from increased plant production remains poorly understood. This "new C" cycle has potential to drive substantial climate forces. Particularly, if hydrologic changes increase anaerobic decomposition of new C (e.g., by priming effect), this then could drive larger contributions to gas emissions, and hence feedbacks related to climate change. Here we examined the priming effect, drivers, and dynamics of the "new C" that is stimulated by climate change in Northern peatlands soil using a stable isotope labeling approach in a long term incubation experiment using surface and deep soil samples. We traced the fate of 13C-glucose added to decomposition incubation into (1) different organic matter (through high-resolution 21T FT-ICR-MS and NMR), then into (2) microbial community (16S rRNA), and finally into (3) greenhouse gases (CO2 and CH4 gas emissions. Glucose addition shifted microbial communities and metabolic pathways deep in the peat core (ancient C) whereas surface soils appeared to be less affected by such perturbation. Deep ancient C pools in the peat core can become sources of carbon dioxide to the atmosphere if the processes contributing to their protection from decomposition are disrupted. Shifts in vegetation accompanied by increase in plant rooting depths can expose deep peat microbial communities to resources favorable for decomposition. This research will help shed new light on the mechanistic basis of biological processes and how these processes change in response to community interactions and shifting environmental condition.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.B11O2196T
- Keywords:
-
- 0439 Ecosystems;
- structure and dynamics;
- BIOGEOSCIENCES;
- 0452 Instruments and techniques;
- BIOGEOSCIENCES;
- 0454 Isotopic composition and chemistry;
- BIOGEOSCIENCES;
- 1631 Land/atmosphere interactions;
- GLOBAL CHANGE