Cellular controls on carbon source-sink dynamics in deglaciated soils
EMSL Project ID
60386
Abstract
When glaciers in polar regions recede because of ongoing climate change, they expose large new areas of nutrient-poor soil. These “pioneer soils,” which have been trapped under the ice and devoid of life for thousands of years, are quickly colonized by microorganisms that establish soil nutrient pools, promote soil development, and shape the biogeochemical dynamics of the future polar ecosystem. The activity of these pioneer soil microbial communities will largely determine whether deglaciated areas act as carbon sources or sinks over the next several decades of climate change, making a predictive understanding of microbial biogeochemical transformations in these systems essential to an understanding of not only the future arctic landscape but also future climate patterns.
In this study, we will identify the microbial taxa and carbon pools that drive the carbon cycle in deglaciated soils of different ages. We will also determine how predicted changes in the arctic climate will shape future carbon source-sink dynamics by affecting underlying cellular processes. To achieve these objectives, we will collect samples of five- to sixty-year-old soils from in front of receding glaciers near both poles, incubate a subset of these samples at projected future environmental conditions (i.e., increased temperature and precipitation), and then examine microbial activity and carbon flux at both the single-cell and community-level scales.
For the single-cell analyses, soil cores will be incubated in a 13CO2 atmosphere so that active autotrophic cells, as well as heterotrophic cells reliant on autotrophic production, become 13C-labeled. Soil cores will then be prepared for fluorescence in situ hybridization [FISH] targeting a conserved carbon fixation gene, followed by nanoscale secondary ion mass spectrometry [nanoSIMS] to visualize 13C enrichment in individual cells relative to their FISH label. These analyses will allow us to determine where autotrophs and heterotrophs live within the soil, which carbon source(s) they are using, and how cellular activity may vary depending on a cell’s microhabitat and relationships with other cells.
The community-level analyses include metagenomic and metatranscriptomic sequencing, as well as in situ measures of soil-atmosphere CO2 flux and soil physicochemistry. These analyses will provide contextual information on how single-cell processes relate to the carbon-cycling activity of the entire community.
The combination of both single-cell and community-level analyses, conducted at both current and predicted future environmental conditions in deglaciated soils of different ages, will provide a uniquely comprehensive understanding of the molecular processes that dictate pioneer soil carbon budgets. Specifically, our data will help develop a long-term, predictive understanding of how microbial activity drives carbon flows and the climate system in one of the most rapidly changing environments on the planet.
Project Details
Project type
Large-Scale EMSL Research
Start Date
2022-10-01
End Date
N/A
Status
Active
Released Data Link
Team
Principal Investigator
Team Members