2024 Abstracts

Linking Root and Soil Microbial Stress Metabolism to Watershed Biogeochemistry Under Rapid, Year-Round Environmental Change


Chikae Tatsumi1*, Kristen DeAngelis2, Charles Driscoll3, Caitlin Hicks Pries4, Pamela H. Templer1, Jennifer M. Bhatnagar1 (jmbhat@bu.edu)


1Boston University, Boston, MA; 2University of Massachusetts–Amherst, MA; 3Syracuse University, Syracuse, NY; 4Dartmouth College, Hanover, NH



Air temperatures are rising causing the winter snowpack to shrink, thereby increasing soil freeze-thaw events in high latitude ecosystems. This project focuses on understanding the shifts in microbial metabolism of soil carbon (C), nitrogen (N), and phosphorus (P), which are the mechanisms that underlie exports at the watershed-level. Researchers are conducting a model-data integration study using the Climate Change Across Seasons Experiment (CCASE) at the Hubbard Brook Experimental Forest (HBEF). At CCASE, replicate field plots receive one of three climate treatments: (1) growing season warming (+5˚C above ambient); (2) warming plus freeze-thaw cycles (+5˚C above ambient in growing season plus up to four freeze-thaw cycles in winter); and (3) reference conditions (no treatment). The team found that warming plus freeze-thaw cycles induce redox stress and select for anaerobic N-cycling microbes. Researchers are working to couple these microbial shifts with changes in the belowground N pool and flux measurements in organic and mineral soil horizons collected over the past decade. The team aims to incorporate both immediate and evolved responses of microbial C, N, and P cycling into new versions of an ecosystem model (PnET-BGC). This research tests conceptual understanding of plant and microbial physiological responses to severe, compounding soil temperature perturbations across seasons, as well as the utility of a forest stand-level manipulative climate change experiment to understand the biogeochemical dynamics of a forest watershed undergoing rapid environmental change.