Diana Wall

Let's start with your interests. Your research investigates the role of soil biodiversity in ecosystem function. When did you become interested in that field?

It was during my postdoc. I was trained in agriculture and studied plant pathogenic nematodes, which is how many people in the US learn how to study these tiny roundworms in the soil. My postdoc at the University of California Riverside focused on all of the deserts in the western United States and finding out the role of nematodes on the energetics of the whole system. I was thrown into looking at many more species that exist in the soil than I'd ever looked at before. Assessing what nematodes do was more challenging than, say, what an eagle or plant does because there are multiple species in one soil sample.

Following that project, I got an NSF grant and started working with some interdisciplinary colleagues in the Jornada Basin of the Chihuahuan Desert, near Las Cruces, New Mexico. My colleagues and I all had an ecosystem approach. Nematodes were just one aspect of the system — we looked at other invertebrates and plant roots, too. We were trying to figure out: would a disturbance like climate change, or too much water, change every single species? But because scientists haven't identified all the species, it was too complex to figure out, even in a hot desert. So, we went deep. My colleague Ross Virginia and I sampled down to 12 or 13 meters. Even at that depth, we still saw nitrogen-fixing bacteria on plant roots, mites, and many nematode species which nobody had yet identified.

We had also hypothesized that since we could see nematodes in the Chihuahuan Desert go into a survival state, there would be a universal gene and that Antarctic nematodes would do the same.

Since the soils we were sampling were so complex, we started talking about doing lab experiments to see how the ecosystem functions. We could isolate one species and see if, for example, CO2 increases when you perturb the system or what happens to the decomposition rate when you have one species. We were at our wits’ end; but then this colleague of mine, Robert Wharton, who was then at the University of Nevada Reno and later went to NSF to work in the Office of Polar Programs, had an idea. He was on the ice in Antarctica, and he said, "Why don't I just send you some soil from the McMurdo Dry Valleys?". Today this would be illegal — but he just gave a soil sample he collected during his fieldwork to some pilot who brought it back to a base near where I lived. I went to the base, and they just handed it to me! The USDA definitely has more rules today.

We got enough data out of that soil sample to write a proposal. Ross and I started researching the Dry Valleys and at that time, the literature said that life didn't exist in the sterile soils. And I just thought, "That can't be true." We had also hypothesized that since we could see nematodes in the Chihuahuan Desert go into a survival state, there would be a universal gene and that Antarctic nematodes would do the same. After we submitted the proposal, we thought we better not get it because we don't know much about invertebrates in the soil, how they function or how many species there are. But we got the grant!

What year was your first field season, and can you tell us about that experience?

That first season was '89-'90. When we landed in Taylor Valley and the helicopter flew away, I just thought, "Oh, my God, it's Mars." None of our standard ecological sampling methods and approaches would work here. We didn't have, for example, an obvious line to sample along towards the forest. We would just record the elevation and age of the rock.

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When we landed in Taylor Valley and the helicopter flew away, I just thought, "Oh, my God, it's Mars."

We found one species when we went into the Dry Valley soils: a nematode resembling Rambo. It has a big, beautiful head and lives in saline soils. Suddenly, we had a valley where the most abundant invertebrate was nematodes. There were some mites and that was it. After two field seasons, we had shown that the Dry Valleys weren't sterile, that you just had to look harder, and that work led to other grants that I continued with Ross. This research led to the McMurdo Dry Valleys Long-term Ecological Research (LTER) grant with Bob Wharton, the first PI.

Can you tell us more about the McMurdo Dry Valleys LTER and how that project came about?

The LTER project is a huge network of sites that NSF has run for many years. At the time, no long-term research was occurring in Antarctica. I was part of an interdisciplinary team that put together a proposal focusing on the ecology of the McMurdo Dry Valleys. These projects need to be interdisciplinary, so we have a lot of people working on different questions. There's the Stream Team, the Lake Team, the Geophysics Team, and the Soil Team. We all help each other, and it is a really fast learning experience of throwing disciplines in a pool all focused on one goal.

The LTER program supports 6-year grants, and the science questions drive whether or not you get the next grant. The McMurdo Dry Valleys LTER has been running since 1992. Diane McKnight and I were one of two principal investigators on the original grant, and it is fantastic to see more women as PIs now.

Did you think the project would last as long as it has?

No way! I mean, it was just pure terror at the beginning. We were trying to learn methods and learn fast. With big team research with so many disciplines, you try to learn a little bit about what everyone is doing when they measure something and how critical those measurements are. So, the first three years were a crash course for me.

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Right, you learned a lot! How long were your field seasons, typically?

Well, they felt longer when I first went down because we couldn't use the telephone; we didn't have email. You had to go to the NSF Office in the Chalet at McMurdo Station if you wanted to contact somebody in the States. Sometimes, I would send a message to my mother to tell her we were okay.

Because we were studying soil and invertebrates, we wanted the soils to be warm, so we planned our field campaign around the seasons. We went by what the data showed on temperature estimates and typically go sometime in December, January, and maybe February. More recently, the LTER research is moving into February. For 10 to 15 years, it was just cold as heck; we never saw any warming. Then, suddenly, in 2002, we started seeing warming. That's the advantage of long-term records. If we hadn't had that previous cold period, we would have thought that the Dry Valleys always had these warmer wet pulses of moisture, which are becoming more frequent.

Interesting. So, you've been to Antarctica over 28 consecutive seasons? Thinking back to all of those seasons, what would be your most memorable Antarctic field experience?

Every time you turn around, you think about how what we see now hasn't changed in 15,000 years.

I’ve been somewhere around 28 times, which is not a big deal, truthfully. Some people have been going down there since they were graduate students, so they have like 30 and 35 years.

The first season was the most memorable because Antarctica was just the most amazing place I've ever been. Every time you turn around, you think about how what we see now hasn't changed in 15,000 years. There aren't many human footprints down there and we cause some of them; so, you feel like, "Oh, my gosh! Should I take another soil sample?". You feel like you want to protect the place and then find all these animals of the same species just living, waiting for a little water so they can chew on bacteria and turn some carbon over.

When was your last field season? And what was the focus of your research at that time?

My last field season was in 2019 as part of a collaborative project led by Byron Adams from Brigham Young University. We went to Shackleton Glacier and were part of a camp with geologists, a microbiologist, an entomologist, and Melisa Diaz, who was previously interviewed in the US Antarctic Interview Series. We looked at the age of the Transantarctic Mountains from the pole as they went down to the coast and at life in the soil at each mountaintop. We wanted to compare communities in soils poisoned from salts coming out from the atmosphere versus soils where the glaciers have receded some. Are there microbes in uninhabitable soils? All of this has implications for Mars.

It was a wonderful field season, and we had great students with us. We just had so much data to be able to put it together as a community. And we had gorgeous weather.

It sounds like a great season! I know it's hard to boil things down, but if you could pick one scientific discovery during your time at Colorado State that you thought was the most interesting or most surprising, what would you highlight?

I'm interested in whether human-induced climate change can affect a single species of an invertebrate in the soil. With warming chambers and all sorts of manipulations, we showed that, yes, it can. A single species can respond. It can also affect ecosystem function and how much CO2 is being released. We showed this with Jeb Barrett from Virginia Polytechnic Institute and other collaborators. I think that changed my whole perspective, that these invertebrates are not just down there like cars you roll off an assembly line. They all have different responses. We have to study more about how the ecosystem is functioning now and how it will change in the future. We haven't got much time to figure that out.

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One of the big reasons I want to talk to you is that you've been heavily involved with SCAR and have been on many different committees. Can you tell me about your different roles?

What is absolutely great about SCAR, whether at international meetings or serving on committees, is that it works across oceans, lakes, and streams.

I got interested after attending my first SCAR meeting, which was probably the best. It hooked me on SCAR because it was the Open Science Conference, so there were all these disciplines. There were people talking about ice cores, and there were geologists talking about where they had found trees.

Of course, most SCAR committees I have been involved with were related to biology. I've served on the SCAR Life Sciences Committee and on many Scientific Research Programs, such as AntECO and AnT-ERA. AntECO focused on the status of Antarctic ecosystems and how to measure change, while AnT-ERA focused on ecosystem resilience and adaptation.

What is absolutely great about SCAR, whether at international meetings or serving on committees, is that it works across oceans, lakes, and streams. There are representatives who know those different ecosystems and the organisms. Regarding Antarctica, we're just beginning to understand how ice flows, what's in the Dry Valleys, and how the populations will evolve. I have the greatest respect for SCAR because of the interchange of Antarctic knowledge.

SCAR meetings are my favorite because I'll learn so much just standing by posters or in the hall. And the early career scientists impress you with where they're going, so it's just a joy to attend these meetings.

Absolutely. I'm going to end with one more question. What advice would you give early career scientists wanting to participate in Antarctic research?

Perseverance is a good thing. Also, make sure you've got a good mentor or a good group of collaborators. Tap into the big network that SCAR has, and don't try to recreate the science we have done in the past; look for fresh ideas. Finally, make sure to keep at it. There's still lots to learn, and the more we know, the better the predictions will be.

I couldn’t agree more. Thank you for your time.