Impacts of prescribed fire on microbially-mediated biogeochemical cycling

Katie Ann Huy, Scott Fendorf (Stanford)

Summary

This project investigates how pile burning affects soil microbial communities and their effect on carbon and nitrogen cycling. This project is funded by an A.W. Mellon Foundation grant.

When vegetation is burned, large amounts of carbon and nitrogen are released into the soil, and these nutrients are ingested and turned over by microbial organisms living in the soil. Researchers are leveraging pile burning that was completed in the spring of 2024 at Jasper Ridge to assess changes in microbial community diversity and deposition and fate of ash-derived nutrients in response to the burns.

To quantify and characterize microbial community diversity and abundance, researchers are quantifying microbial cells before and after burns, then sequencing DNA to identify microbes and their potential functions. After fires, researchers expect to see a dominance of heat-resistant, fast-growing microorganisms.

To track the effects of fire on carbon and nitrogen, researchers are quantifying ammonium and nitrate, pyrogenic carbon, and carbon dioxide before the burns and monthly after the burns. Combined with sequencing and predictive modeling techniques, the presence and abundance of nutrient cycling microbials groups will be measured. After the burns, researchers anticipate higher levels of ammonium, pyrogenic carbon, and carbon dioxide, with decreases in all three over time.