The World Below the Ground

For Dyson Professor Bill Eaton, PhD, the classroom is truly mother earth.

As a tropical soil microbial ecologist, Eaton has been studying how climate change and human land management impact soil ecosystems for over two decades. Currently, Eaton is in Costa Rica making valuable contributions to this ever-growing, ever-important field.

“In respect to the world below the ground, for a long time, there was very little known in ecology about the connections between the microbial world and the carbon and nitrogen cycles,” said Eaton. “Microbial ecology is now just entering into its golden age as a result of new technologies allowing for the identification of microbial species based simply on sequencing of environmental DNA samples, rather than the need to grow the microbes in culture.”

What exactly is microbial ecology? The emerging field refers to the study of microscopic organisms, and their interaction with each other and their environment. While we may often think of soil as simply dirt, the innumerable complexities of that dirt are only beginning to be understood; namely, how changes in soil composition and carbon and nitrogen cycles can determine short-and long-term environmental health.

As Eaton notes, much of the advancements in this field can be credited to advancements in DNA technology.

“The DNA technology has become so advanced, we’ll take soil samples in different areas, extract DNA, send it to get processed, get 55,000 lines on an excel spreadsheet each representing a bacterial species or 20,000 lines representing fungal species,” said Eaton.

“The DNA technology has become so advanced, we’ll take soil samples in different areas, extract DNA, send it to get processed, get 55,000 lines on an excel spreadsheet each representing a bacterial species or 20,000 lines representing fungal species,” said Eaton. “Most of these microbes are likely not culturable, and in the past would not have been identified. This has allowed ecologists to ask really interesting questions with respect to changing microbial diversity and functional groups, and the use of complex organic carbon to produce more biomass as opposed to CO2 release—which occurs with the break down of simple compounds.”

Tropical soil environments, as Eaton describes, are arguably even more important to study, because of their critical importance in global nutrient cycling. Thus, he has made it his mission to investigate these ecosystems further; with the aim of better understanding how tropical soils are affected by human and nature-induced disturbances, and how different restoration practices can aid ecosystem recovery.

In the past two years alone, Eaton has published five different studies across a number of different academic journals. One study, which Eaton published in PLoS One with the assistance of a number of Pace student-researchers, looks at the impact of Hurricane Otto—a Category 3 hurricane that hit Costa Rica in November 2016—and how soil and fungal communities might change due to a drastic weather event.

This study was in fact, one of the first of its kind—something Eaton credits to happening by chance.

“The main reason why no one has done a before and after study impacts of hurricanes on soils is that you can’t predict where one is going to hit. You have to have plots in a forest before it hits; and you have to study after. I happened to have plots in three different types of forests in the Northern Zone of Costa Rica that had been studied before Hurricane Otto hit, and have been studied since then.”

“There is an academic maturation, but also a human maturation experience. Students come down, and they come back changed. You can’t spend a month here and not have different perspective of the world.”

Though his research acumen and career experiences have made him uniquely qualified to make considerable academic contributions to a field that is becoming more salient by the day, Eaton also has become a mentor to students. By working with students in Costa Rica, Eaton has helped train a generation of future biologists—his rule is that he treats students as “scientists first”—and has seen students mature and grow substantially from simply spending time in Central America.​

“There is an academic maturation, but also a human maturation experience. Students come down, and they come back changed. You can’t spend a month here and not have different perspective of the world.”