Fernanda Santos: Digging into charred landscapes for clues to carbon storage

With wildfires increasing in scope and intensity around the world, Fernanda Santos’ research into how such calamities affect soil carbon storage has taken on new urgency.

The Oak Ridge National Laboratory soil biogeochemist has been digging into charred landscapes to better understand what happens to belowground biodiversity after such disturbances and how that affects the soil carbon cycle.

The Earth’s soils hold more than 3 gigatons of carbon—triple the amount of carbon in the atmosphere. Scientists are eager to know how disturbances such as wildfires, especially repeated and severe fires, affect long-term carbon storage, and to incorporate that knowledge into predictive climate models.  

“We know that microorganisms in soils and around plant roots play a key role in the carbon cycle. We’re investigating what happens to carbon when microbial-mediated belowground processes and aboveground vegetation are disturbed. How will this ecosystem change if microbes and plants are stressed?” Santos said.

Her research has taken her to ecosystems in the mountains of Brazil, the upper peninsula of Michigan and the U.S. Southwest and Southeast. In June, she traveled to Alaska to sample soil in the tundra as part of the Next-Generation Ecosystem Experiments – Arctic project led by ORNL.

“It was the first time I’d been in a tundra ecosystem and my first encounter with permafrost,” Santos said. “I was able to dig down only so far into the organic material before hitting something I thought was a rock but was actually frozen soil — it was very exciting.”

She is analyzing how the active layer of soil near the surface, full of organic matter, is affected by wildfire and can even help fuel fires. She is also digging deeper into soil layers to unearth clues as to how fires in decades past influence carbon storage.

Developing a passion for soil science

Santos grew up in Brazil and attended the State University of Rio de Janeiro with the intention of becoming a geography teacher. But in one of the school’s labs she noticed some shiny bricks on a table. They turned out to be soil samples embedded in resin, which enables researchers to better examine mineral content in different soil layers. Ensuing discussions with graduate students and professors, some borrowed books and a couple of weekend soil sampling trips later, Santos had her feet firmly planted on a new career path as a scientist.