USAP-DC

Part I: Non-technical description: Earth’s terrestrial ecosystems have the potential to either slow down or hasten the pace of climate change. The direction depends in part on both plant and microbial responses to warming. This study uses Antarctica as a model ecosystem to study the carbon balance of a simplified ecosystem (simplified compared to terrestrial ecosystems elsewhere) in response to a warming treatment. Carbon balance is dictated by sequestered carbon (through photosynthesis) and released carbon (plant and microbial respiration). Hence, to best assess plant and microbial responses to warming, this study uses a plant gradient that starts at the glacier (no plants, only soil microbes) to an old site entirely covered by plants. Experimental warming in the field is achieved by open-top chambers that warm the air and soil inside. The net ecosystem carbon exchange, the net result of sequestered and released carbon, will be measured in warmed and control plots with a state-of-the art gas exchange machine. Laboratory temperature incubation studies will supplement field work to attribute changes in carbon fluxes to individual plant species and soil microbial taxa (i.e., “species”). Data from this study will feed into earth system climate change models. The importance of this study will be shared with the broader community through the production of a video series created by an award-winning science media production company, an Antarctic blog, and through interactions with schools in the United States (on-site through Skype and in-person visits). Part II: Technical description: Responses of the carbon balance of terrestrial ecosystems to warming will feed back to the pace of climate change, but the size and direction of this feedback are poorly constrained. Least known are the effects of warming on carbon losses from soil, and clarifying the major microbial controls is an important research frontier. This study uses a series of experiments and observations to investigate microbial, including autotrophic taxa, and plant controls of net ecosystem productivity in response to warming in intact ecosystems. Field warming is achieved using open-top chambers paired with control plots, arrayed along a productivity gradient. Along this gradient, incoming and outgoing carbon fluxes will be measured at the ecosystem-level. The goal is to tie warming-induced shifts in net ecosystem carbon balance to warming effects on soil microbes and plants. The field study will be supplemented with lab temperature incubations. Because soil microbes dominate biogeochemical cycles in Antarctica, a major focus of this study is to determine warming responses of bacteria, fungi and archaea. This is achieved using a cutting-edge stable isotope technique, quantitative stable isotope probing (qSIP) developed by the proposing research team, that can identify the taxa that are active and involved in processing new carbon. This technique can identify individual microbial taxa that are actively participating in biogeochemical cycling of nutrients (through combined use of 18O-water and 13C-bicarbonate) and thus can be distinguished from those that are simply present (cold-preserved). The study further assesses photosynthetic uptake of carbon by the vegetation and their sensitivity to warming. Results will advance research in climate change, plant and soil microbial ecology, and ecosystem modeling. Science communication will be achieved through an informative video series, a daily Antarctic blog, and online- and in-person visits to schools in the United States. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

Person	Role
van Gestel, Natasja	Investigator and contact
Hungate, Bruce A.
Dijkstra, Paul

Antarctic Integrated System Science	Award # 1947562
Antarctic Earth Sciences	Award # 1643871
Antarctic Organisms and Ecosystems	Award # 1643871

USAP-1947562_1

None in the Database

Repository	Title (link)	Format(s)	Status
USAP-DC	2022-2023 Palmer Station terrestrial carbon fluxes - field warming experiment	Text File; Adobe Portable Document Format (PDF); Microsoft Excel (OpenXML)	exists
USAP-DC	Soil moisture and soil temperature data (0-5 cm) near Palmer Station, Antarctica	Adobe Portable Document Format (PDF); Microsoft Excel (OpenXML)	exists

1. Purcell, A. M., Dijkstra, P., Hungate, B. A., McMillen, K., Schwartz, E., & van Gestel, N. (2023). Rapid growth rate responses of terrestrial bacteria to field warming on the Antarctic Peninsula. The ISME Journal, 17(12), 2290–2302. (doi:10.1038/s41396-023-01536-4)
2. Foley, M. M., Stone, B. W. G., Caro, T. A., Sokol, N. W., Koch, B. J., Blazewicz, S. J., Dijkstra, P., Hayer, M., Hofmockel, K., Finley, B. K., Mack, M., Marks, J., Mau, R. L., Monsaint-Queeney, V., Morrissey, E., Propster, J., Purcell, A., Schwartz, E., Pett-Ridge, J., … Hungate, B. A. (2024). Growth rate as a link between microbial diversity and soil biogeochemistry. Nature Ecology & Evolution. (doi:10.1038/s41559-024-02520-7)