Waldbauer MONet Request
EMSL Project ID
60920
Abstract
The Arctic is warming twice as fast as the rest of the planet, and Arctic soils currently store twice as much carbon as the entire atmosphere. These two facts make understanding how Arctic soil microbial communities are responding to climate change — particularly with regard to the potential respiration of the enormous reservoir of stored organic carbon — urgent for robust predictions of global environmental change in the coming decades. Greening of vegetation cover across the Arctic landscape — notably the shift from tussock/sedge-dominated tundra to a tundra more covered by taller, higher-biomass woody shrubs — is one of the most prominent climate-driven shifts in Arctic terrestrial ecology, with consequences for the soil microbial community that are only beginning to be understood.
In this project, we are using metaproteomics to document the microbial metabolism that underlies soil carbon and nutrient cycling processes in an Arctic tundra landscape undergoing warming-induced greening. Sampling focuses on the Toolik Lake area in the northern foothills of the Brooks Range, North Slope region of Alaska, site of 30+ years of longitudinal ecological research. In order to generate a deep and comprehensive view of protein expression across the soil microbial community, we are employing high-precision quantitative metaproteomics by in vitro peptide isotope tagging (diDO-IPTL). We will also use a proteomic nitrogen isotope tracking approach, developed in our group, to directly assay the incorporation and biosynthetic routing of 15N-labeled substrates by specific members of the community, which will provide new insights into critical nutrient dynamics of these N-limited soils. These new measurements will enable us to address key open questions in Arctic soil biogeochemistry, including:
• How are metabolic functions partitioned between and among bacterial and fungal communities in ‘baseline’ (tussock/sedge) versus ‘greened’ (shrub) tundra?
• Which metabolic processes are most limited by nitrogen scarcity in Arctic soil microbial communities throughout the deepening active layer, and how does vegetation influence the belowground N economy?
• How will nitrogen availability modulate the capacity or tendency of active-layer microbial communities to access long-stored organic carbon as thaw depth increases?
We propose to sample 12 locations in the Toolik area for analysis by the MONet program. These will allow us to span the vegetation cover types (wet and dry sedge, tussock and upland and waterway shrub tundras) on the two different glacial land-surface ages (~60kyr and ~20kyr) present in the area. The MONet data will hugely enrich our ability to interpret our metaproteomic data in terms of the local microbial communities and edaphic properties. The metagenomic sequencing from closely-paired samples will enable more comprehensive peptide identification from our metaproteomic mass spectral data, especially for undersampled community constituents such as fungi. The molecular characterization of water-extractable organic matter will illuminate the solutes exchanged among the microbial communities and with root systems in the different tundra environments. Other measured soil parameters, notably the pore network structure and mineral-associated organic matter, have rarely been directly paired with community metaproteomic data and will likely reveal new kinds of biogeochemical interactions.
Project Details
Project type
MONet
Start Date
2023-06-01
End Date
N/A
Status
Active
Released Data Link
Team
Principal Investigator
Team Members