ORNL: Matthew Craig: Solving the mysteries of soil carbon storage

Matthew Craig grew up eagerly exploring the forest patches and knee-high waterfalls just beyond his backyard in central Illinois’ corn belt. Today, that natural curiosity and the expertise he’s cultivated in biogeochemistry and ecology are focused on how carbon cycles in and out of soils, a process that can have tremendous impact on the Earth’s climate.

Nearly 80% of terrestrial carbon is found in soil. Four times as much as is stored in plants and three times more than the amount of carbon found in the atmosphere. Craig is working on an ambitious project at Oak Ridge National Laboratory: building a comprehensive model of the formation and decomposition of soil carbon as part of a Department of Energy Scientific Focus Area project on terrestrial ecosystem science.

“I came to ORNL to take my experience as a field researcher and an experimentalist and learn how to integrate these different science approaches using modeling,” Craig said. “Models leverage experiments and field observations, and let us combine multiple hypotheses and theories to understand how whole systems function and to make predictions about Earth’s future.”

Some of the questions he’s trying to answer include how the interaction between plants and soils allow an ecosystem to build up or lose carbon, how much carbon soils can store, and how certain ecosystems might be stimulated to store more carbon.

In another project, he is working with colleagues to identify genes in bioenergy crops that stimulate the accumulation of carbon. Craig is also part of the Next Generation Ecosystem Experiments-Tropics project, where he studies how root systems take up nutrients—a key process in models of forest dynamics.

Craig first heard about ORNL through its Free-Air CO2 Enrichment, or FACE, experiment and the more recent Spruce and Peatlands Responses Under Changing Environments, or SPRUCE experiment. His doctorate advisor worked on elevated CO2 experiments, and he’d also heard ORNL scientists like Colleen Iversen speak about FACE at academic conferences.

Joining big team science

“ORNL does ecosystem manipulation better than just about anywhere,” Craig said. SPRUCE, which investigates the impact of elevated temperature and CO2 levels on carbon storage, “put Oak Ridge on the map for me when I was in school. There’s nothing like it going on anywhere else.”

“I wanted to try out the national lab environment because I was attracted to this idea of big, multi- investigator projects,” Craig said. A self-described biogeochemist and ecosystem ecologist, Craig said he’s interested in an interdisciplinary approach to science. “One of the things I like about ORNL is that you get to branch out and apply your skill set to new science approaches and answer new questions.”

By the time Craig applied for college, he knew that he wanted to study environmental science. “That mostly came from being outside all the time when I was a kid, exploring the woods in the river valley where I grew up in central Illinois. I would go and just sit by these 8-inch-high waterfalls and really appreciate them because I lived in a suburb where most available land was either covered in housing or crops. So we spent a lot of time in any of the little forest patches we could find.”

He first became interested in biology in a high school human physiology class during a lesson on the human eye. He went on to earn a bachelor’s degree in biology at Augustana College in Rock Island, Illinois. During that time he spent a summer studying the nitrogen cycle in an urban marsh, a collaboration led by an ecologist and an analytical chemist that encouraged his interest in multidisciplinary science.

Craig earned a master’s degree in natural resources and environmental sciences at the University of Illinois Urbana-Champaign, and then a doctorate in ecology, evolution and behavior with a minor in geography at Indiana University in Bloomington. He came aboard ORNL as a postdoctoral researcher in 2019 and moved into a staff position two years later.

Pursuing a passion

Craig lauds ORNL’s science culture for encouraging collaboration.

“You have multiple people driving towards the same questions with complementary skill sets. The quality of the personnel we attract and the nature of these projects leads to a lot of interaction that you don’t get in many other settings,” he said. Yet he’s been able to find a balance in his work at the lab.

“You’re able to contribute and collaborate on big projects here, but you also get to specialize and still pursue things you’re interested in,” Craig added.

He’s also a fan of the region. “I love living in this part of the country,” he said. Some of his research as a master’s student took place near Asheville, North Carolina, and he enjoyed traveling to the Tennessee side of the Smokies as well. It was a big factor in deciding where to pursue a postdoc position. “The waterfalls are bigger here,” he said. “Like, they go up past my knees.”

He and his family enjoy hiking and spending time in area parks such as Ijams Nature Center, the zoo and the Urban Wilderness trails in Knoxville. “I’m also the cook in the family. We have a three-year-old. I watch baseball and do a little woodworking when I have time. That’s mostly what takes up my time after science.”

Craig advises young people interested in an environmental science career to make sure they’re well versed in math and computer science. Those disciplines “underpin so much of the cutting-edge science and the future of the field,” he said.

“Anyone can be a scientist. It’s just a different way of thinking about the world and trying to understand it,” Craig said. “So get the right people in your corner and go for it.”