Rooted to Her Students

Nancy Johnson knows what it is like to be marginalized. As a student with aspirations for a research career, she was told by a male advisor that she couldn't have both a career and a family. As a freshly-minted PhD with two children, she presented revolutionary research about mycorrhizae—mutually-beneficial associations between a naturally occurring subsurface fungus and plant roots—to a community of specialists who scorned her findings.  

Thirteen years after publishing her controversial—and now well-accepted—findings, Johnson is in a different position. She is one of the most widely-respected soil ecologists in the world, as well as the director of the Undergraduate Mentoring in Environmental Biology (UMEB) program at Northern Arizona University. In that role, she helps students traditionally underrepresented in academia.

"The Undergraduate Mentoring program is all about trying to increase workforce diversity among environmental biologists," says Johnson. "Historically, the field has been pretty monoculture. This program tries to increase participation among underrepresented populations. Many Native American and Hispanic students have been UMEB Fellows. Over the past 10 years, we've supported more than 50 students."

As part of the program, which is funded by the National Science Foundation, undergraduate students receive up to $12,000 in scholarships and wages, and have the opportunity to conduct research with faculty mentors who are experts in their fields. And, according to Johnson, the relationship between UMEB Fellows and their faculty mentors is win-win: students gain valuable research experience, professors gain a research assistant, and in the process, the field of environmental biology is advanced.

"We try hard to place the students in laboratories with professors who are studying what they're interested in," she says. "We don't tell the students what they have to study, we ask them, 'What do you want to study?' because the whole idea is to give these talented students an opportunity to delve deeper into an area that they really like. Hopefully, they'll excel at it and then want to go on to graduate school."

According to Johnson, the program is beginning to positively impact the effort to bring greater diversity to the scientific academy. Several students from the initial cohort have gone on to earn advanced degrees, and Northern Arizona University undergraduate students continue to use the program to explore areas related to chemistry, biology, forestry, botany and more.

Understanding ecology and agriculture

Johnson is just as committed to making a difference in her role as a soil ecologist. Currently, her inquiries into mycorrhizae have the potential to help researchers understand some key components related to global warming. Right now, says Johnson, no one is certain how much carbon that soil beneath grasslands can sequester in complex organic compounds. If we could better understand carbon dynamics in soil, she says, we could more accurately predict how agricultural practices, for instance, affect global carbon dioxide levels.

"One of the big places where carbon gets stored is below ground, in the soil," says Johnson. "Because mycorrhizae are so abundant, they are probably a pretty important carbon sink. But we don't really understand the factors that control how much gets stored down there. In some situations, soils can be a source, especially in agricultural systems. But when agricultural systems are abandoned and turn back to forests they can tie up a lot of carbon. But not much is known about the effects of grassland management on soil carbon dynamics."

Johnson is also adamant about protecting ecosystems from unnecessary risks. For example, millions of dollars worth of mycorrhizal fungal inoculations are sold each year as part of agricultural, horticultural, and ecological management programs. According to Johnson, no one knows whether these massive efforts are helping or harming the environment.

"I'm convinced that most commercial mycorrhizal inoculum is snake oil," she says. "Marketers are convincing the public that unless you buy their product and put it in your soil then you won't have mycorrhizae and your plants won't do well. But mycorrhizae are there anyway [they are naturally occurring]. Rather than introducing non-local mycorrhizal fungi, we should simply manage the existing mycorrhizal symbioses to maximize their benefits. This approach saves money and avoids the potential risks associated with introduction of non-native species."

As her work continues, Johnson hopes to keep exploring the unknown. She recently spent a month in Africa’s Serengeti region to better understand mycorrhizal structure and function across natural soil fertility and precipitation gradients. As a mentor to undergraduate students—both in the classroom and as director of the UMEB program—she will continue to reinforce that sense of exploration.