Coupled dynamics of carbon geochemistry and microbial communities in grassland soils
Abstract
Biogeochemical cycling of carbon (C) in grassland soils is crucial to the global C cycle as soil is one of the largest C reservoirs on earth. Thus, the transformation of C in soil strongly regulates the terrestrial-atmosphere C flux in C cycling models. Microbial metabolic processes play a key role in the decomposition and transformation of soil organic matters (SOM). We hypothesized that a pool of organic molecules is transferred from dissolved to sorbed phase during incubation without external C inputs, and such dynamic C chemistry is responsible by the composition of microbial communities. This lab-scale incubation study coupled with high-resolution mass spectrometry and metagenomics allows us to investigate the coupled dynamics of microbial community composition and C transformation across a network of field sites. We found that the diversity of dissolved C composition decreased, whereas sorbed compounds show increased diversity by the end of the incubation. Meanwhile, respired C may account for the lessened diversity of C molecules in dissolved phase as some organic molecules at T0 were more bioavailable to microbes and easily respired. Metagenomics results indicate a dominant habitat effect and little time effect on microbial community composition across six grassland soils, suggesting the incubation alters the composition of microbial community by decomposing SOM, resulting in shifts in available substrates among ecosystems. This study demonstrated the dynamic and interactive C pools in soils, providing an advanced understanding of the biogeochemical cycle of C in grasslands.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.B21H2290Z
- Keywords:
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- 0414 Biogeochemical cycles;
- processes;
- and modeling;
- BIOGEOSCIENCES;
- 0428 Carbon cycling;
- BIOGEOSCIENCES;
- 0463 Microbe/mineral interactions;
- BIOGEOSCIENCES;
- 0486 Soils/pedology;
- BIOGEOSCIENCES