Edgewater, Maryland is home to the world's longest-running field experiment on climate warming. We speak with the project's principal investigator and an undergraduate researcher who spent two summers studying the effects of elevated carbon dioxide and enriched nitrogen on fluxes from Phragmites, or common reed. You'll hear about the challenges of building and maintaining microclimates, information scientists have learned about our planet's future, and what scientists at the Smithsonian are working on next.
Transcript
Tyler: So, the field of research on climate change has grown significantly over the past decade or two, and technological advancements have created opportunities for experiments that would not have been possible 10 or 20 years ago.
The SMART-X experiment is a great example of that and these large-scale climate manipulation experiments. But what a lot of people don't think about is just the complexity of controlling climate. And even at a small scale, there is no easy task. Can you start off by telling us a little bit about the experiment? How did you design a system to measure the impact of an altered climate?
Genevieve: So, SMARTX is the brainchild of another scientist here at SERC called Roy Rich, and the way it works is that we have plots in marsh, and then we have other plots that we keep exactly 1.4, 3.7, and 5.1 degrees warmer than those plots and we're continuously tracking temperature from above and below ground to make sure that the warm plots always stay that exact same amount of warming, which in itself is kind of a technological feat because we're measuring temperature every 15 minutes and constantly changing how much power we send to the above-ground heaters and the below-ground heaters to always keep them in the same seasons, the same diurnal cycle.
Tyler: The physical process for doing that is obviously quite intense. Can you comment a little bit just about the system for monitoring the ecosystem? You've got kind of the threefold aspect of it. One is actually changing the environment, and the other aspect is the monitoring that you're doing. Can you give us just a little bit of background on that?
Genevieve: Yeah, I mean, we would love to monitor everything, and so we measure methane flux and CO2 flux out at the sites every month. We also measure some of the chemistry in the porewater to try to understand what's driving the fluxes. We measure plants, there's some people doing microbes, all the things that go into plant ecology.
Tyler: I had worked on the SPRUCE experiment before. I know they had the field of dreams - if you build it they will come-type of analogy. I imagine you guys have a similar experience of, anything that can be measured, there's an expert out there that offered their expertise.
Genevieve: Yeah, for sure. Just like anything in field ecology, there's probably been four different scientists who have come and said, you have this awesome experiment. We want to do this. And we’re like, “sure, you can do whatever you want.”
Tyler: Are there challenges that arise from having so many people trying to operate in a small spatial area?
Genevieve: Yeah, I mean. The SMARTX plots are 2 meters by 2 meters. So we cannot take soil cores every single year, for example. We're not going to test any methods in there. We're only going to let people who know what they're going to do is going to work. But there's no point in building an experiment just to kind of hold it to yourself and say, oh yeah, I'm going to measure the methane. Finding all the pieces of the puzzle and putting them together, that's what's fun. And you can't do that without other people and their expertise.
Tyler: It's a great opportunity for collaboration across disciplines, across different backgrounds. Somebody might have a very different perspective that helps you to understand your data set that you wouldn't have realized otherwise.
Genevieve: SMARTX Is just one of the long-term experiments on the site. So there's a lot of collaboration going across all of the climate change work that we have.
Tyler: Sophia, do you want to give us a little bit of background on your experiment and the work that you do?
Sophia: I work on the Phragmites elevated CO2-enriched nitrogen plots located, I think, about a quarter mile away from the SMARTX plots. They are really large 16-feet open chamber plots with native reference areas and Phragmites reference areas to sort of understand how Phragmites invasion is altering different aspects of the wetlands. It has, I believe, tubes of CO2 that are pumped from the main house all the way down to a “dog house”, is what we call it, but it's just a box that controls all our electric stuff while out in the marsh. And then there are air pumps that pump it underground and into the chambers. This was also designed by Roy Rich. His lab also operates hives, which are located inside the chamber so we can monitor how much CO2 is actually being received in the chambers.
There are monthly fertilizations by technicians at GCREW. Mostly they are from Genevieve's lab. My project is looking at methane emissions and greenhouse gas emissions in these sites and how both these environmental factors and Phragmites is altering that. It was really interesting to figure out how do we measure methane emissions around really large plants and dense rhizomes and trying not to disrupt the marsh space because we have to find a way to insert the collars to isolate soil, but we also don't want to disrupt it so much that we're damaging the marsh itself and altering the marsh microbiome.
So, that was something that me and my PI, Tom Mozdzer, had to sort of figure out what's the best way to do that. Oftentimes, it's just like a fun solution. We made, like, a cookie cutter and then we kind of just slid a PVC in and hoped that it would stay relatively stable and the marsh wouldn't push it out. Hopefully, I can line my data up with Genevieve's to sort of see, are we noticing the same trends across the marsh over the season, or are they different?
Tyler: How do you approach analyzing a dataset like that has so many interacting variables?
Genevieve: It's driven by the tidal fluxes, driven by the temperature, it's driven by the plants. SMARTX has 2 kinds of plant species? But of all of those plant species are going to need different oxygen, different carbon in the soil. It's really hard because you cannot make a figure that has six different axes. You've got to take the things you think are most important.
Tyler: Do you have any, like, I don't know, anything outside of what you expected, any effects that weren't anticipated or even logistical challenges that maybe didn't arise initially, but occurred over time?
Sophia: Something I hadn't really considered, the different plant varieties will affect how much carbon they have. And something I initially didn't understand was why one of my replicates had higher carbon dioxide emission rates. And I was like, that's so weird for the native plant groups. Like, I'm not understanding.
And then I realized that actually it's dominated by a different group than the other two replicates are. That one is dominated by Spartina, and then the other two are dominated by Shinoplectus americanus. It's similar to Phragmites, which is why I didn't see that difference, except in the first replicate, we were kind of wondering, could there be a plant genetic component? Because we know that these environmental factors are selecting for certain genotypes and they're responding better.
This is something that goes beyond my project and goes on to a future student project where they could look into is there a relationship between Phragmites genotype and the amount of greenhouse gas emissions released nearby either by the plant or by the soil. That's something that we hadn't initially thought would be like the driving factor. We figured it would be like elevation, flooding, soil temperature, but that one is becoming something that we're looking into. Even though we had these like really interesting experiments.
Genevieve: I consider what the temperature is in each of my 30 plots, but we're still falling victim to just like all the business of the work. I've never worked in a coastal wetland before this site, and one of the first things that happened to me when I was trying to measure plots up here, you have to look at the tides.
Tyler: So, these experiments are intended to give us a glimpse into the future and what Earth's climate is projected to be like in 2100. We can learn a lot about the future of ecosystems by studying how they behave in these expected future climates. But with complex experiments like this, it is important to be sure that the results are interpreted correctly and used in developing policy for a better future. How can other people extrapolate your results to a larger scale? Are there specific ways that you would caution people to interpret your data correctly?
Genevieve: So, it's all publicly funded data, so it's all publicly available. So anyone can take it on the website and then do whatever they want to craft policy. Our site is a very, very well instrumented site. So we have these experiments, we know really, really well what's happening. We try to use them as a way to say, okay, these are like the three most important things that you need to study in order to understand the future world. And then you can go further and do that at another site.That's not feasible, to have this much instrumentation or this much effort going into a lot of sites across the US, across the world. So, we can figure out these are things that matter, whether that's the vegetation or the genotypes. A lot of our stuff is funded by the Department of Energy, so a lot of it goes into modeling. That's how we work on scaling-up data. We know what's happening at the site, and then they can generate better predictions for the future, depending on what we work here.
Tyler: Do you work directly with those modelers?
Genevieve: All the DOE grants require that you have modeling people. We have two different models right now.
Sophia: My data will be publicly available. That's part of my internship and working with the Smithsonian, but I think it's just highlighting the importance of long-term research. A lot of times, flux measurements sometimes are done just over one growing season, but I'm finding a lot of inter-annual variation just between two. You can't just base a model off of one time point, even if you're going over a season and you think that encapsulates it.
There are so many different environmental factors that change year to year, especially with climate change, which affects how many storms we get, or what's the duration of our heat waves, things like that, which can really alter the biogeochemistry of the wetland and influence how much methane we get. Last year I saw a lot of methane emissions, but this year it was more flooded, so it had longer time to oxidize in the water before coming up. Things just rapidly change, and it highlights the importance for long-term studies to better refine models so that we can predict what can be done or how will different places respond to these factors.
Jess: Yesterday I was in the field and somebody happened to see us doing research who believed that elevated CO2 was going to encourage plant growth, which is actually a scientific concept, CO2 fertilization, but one that's misconstrued. While some plants will absorb more carbon and grow more, others will suffer from drought and the other effects of climate, especially in regions that are already at their thermal limit.
Doing this kind of research, this ecosystem research, shows that everything is kind of in balance. Sometimes you can tip the scales a little bit, you know, with climate mitigation or restoration, but there's not really a way to put carbon in somewhere and not have it come out somewhere else.
Genevieve: It's kind of funny that you mentioned that. The first 20, 30 years, we saw a really positive CO2 effect at first. You give the plants more CO2 and they're super happy and it's going to take off, but not anymore because they're not too dry - they're too wet. Sea level comes up in these marshes. The plants are drowning, basically. CO2 fertilization is an important thing, but you're gonna have too dry or too wet.
Tyler: Are there any questions about the impact of warmer or chemically different climate that can't or still haven't been answered?
Genevieve: Yeah, many. When working on warmer wetland sort of things, we can say methane is rapidly increasing, especially with these plant communities, but we can’t say why. We need to know the mechanisms, and the mechanisms can apply to other sites or to policy.
Tyler: Even if you answer a question, it probably opens a can of worms for three or four more questions. Keeping the experiments going and keeping the monitoring going, keeping collecting the data can help to keep building our knowledge base.
Genevieve: That is kind of the power of the Smithsonian, that we can run these experiments for decades and keep that continuity going.
Tyler: You get people involved, you get more experts involved, you get more data, you get more knowledge. It all keeps building. It's kind of a snowball effect.
Sophia: My project actually is kind of like a little side shoot that they didn't really anticipate going down. My professor, when he first started this, he didn't think he would be so based in evolution and how the plants are changing and into the different genotypes. He wasn't necessarily expecting this is what he would be focusing on. But as you watch these long-term things play out, like you just...they respond. And it's really like, it's watching plants adapt and evolve at a rapid pace is so interesting because then you can ask all these different questions.
Another student in his lab who's looking at seed germination rates of Phragmites from the different genotypes and how they differ. Like there's a wide variety of things you can do from biogeochemistry to fecundity. It's a wide world and you can ask as many questions as you want. And I promise you, there'll still be more you can ask later, which is the really beautiful thing about working at Smithsonian and working at long-term research sites. It allows you to look at a variety of different things and compare things.
Like, I ran a decomposition experiment and they had one from, I think, about like five years ago. So then we can examine how those are changing and you can always check with your collaborators and other people who work at the Smithsonian and be like, “hey, like, I'm seeing this. What are you seeing?” Then sort of extrapolate larger results. Part of the things that I really love about the Smithsonian is you get this hodgepodge of scientists who all come together and we're able to ask really big questions by asking really little ones individually.
Tyler: Genevieve, you've studied wetland fluxes for more than 10 years. Are there other methods you're considering beyond chamber-based fluxes that might replace the current standards of measurement? How do you recommend other scientists stay current with new methods and trends when taking classes isn't an option?
Genevieve: If you want to know what's actually happening on the ground, I think you need to measure all the plots. What I put in four years ago at this point are automated chambers. Those I love. You can just figure out what's happening. It kind of combines the best of a chamber and a flux tower, because you get basically continuous methane CO2 and nitrous oxide measurements from this little patch of ground. You know what the plants in there are, you know what the water in there is, and then you can start figuring out these mechanisms that pull together all those pieces. All of what I've learned and I tried to pass on was just communication. You see someone with a cool poster at a conference and you go talk to them. So, we do a decent amount of sharing across institutions.
Tyler: I don't know what your auto chambers look like - I've worked on some in the past. They can be fickle. Any words of wisdom for people on the technical side of maintaining these things?
Genevieve: You don't always need a background in engineering to do this. You just kind of need to be willing to try. When our systems fall apart, it’s usually some combination of the data logger - some communications wires not put in the right spot or it’s the actual physical chambers. In the past few years, we developed 3 different versions of these autochambers, so we are improving them every time. It means things break in different ways. Just be willing to mess around.
Tyler: Sophia, can you tell us what is an REU? What does the schedule look like, and is there some training involved?
Sophia: An REU, or Research for Undergraduates, is a specific type of internship program where undergrads are given the opportunity to do their own research. Mine was in environmental science or biology, that area. The Smithsonian has all their interns meet and do some trainings before you start, like; “how to make the most of your internship”, “here's what the Smithsonian is”. And then once you actually get there, you get another orientation that's more specific to your site. You get a safety orientation about what you can do, what you can't do. There's some ground rules of “maintain the places”, “here's how to conduct yourself in a workplace”, and we get a nice tour. Something I really liked about this internship is we have professional development sessions that happened every Friday. So for the most part, your schedule really was created by your PI, who is your boss.
Some people were working 8 to 4, some people working 9 to 5, some people were working 7 to 3 or even earlier if they had to be at a research site that was on an island and had to commute. But on Fridays, we all met up. We had professional development sessions covering networking and how to use R, which is a statistical software, which is really important because we are conducting our own research. Stats is probably the bane of most people's existence, but it's really fulfilling when you're able to analyze your data correctly and produce some results. You get an opportunity to meet a lot of different people, learn skills, refine them. If you have the opportunity, I would do it…specifically at the Smithsonian, although I'm kind of biased.
I think it's really great. It's a very lovely workplace with a bunch of kind individuals who love to talk to interns and give them a piece of their time for chatting or for questions. It definitely shaped where I want to go into the future.
Tyler: Any other exciting projects or things that are in the pipeline, anything else you want to share with us?
Genevieve: We have a cool project- another methane flux project that we just started this past September. We're going to take those autochambers I mentioned, but they're set up in Brazil. Its a savannah that it goes down into a wetland with palm trees. As the water table fluctuates wildly between the wet season and the dry season, what does that do to the methane emissions? There are different plants or different locations across the landscape. So it's kind of fun to take the technology we've developed, these methane flux chambers, and deploy them somewhere in the middle of nowhere.
Sophia: I'm finishing up my senior thesis. I will hopefully be turning my research into a paper, so possibly be on the lookout for that. For my lab, the big other project that occurred this past summer and is still ongoing was the marsh organ project, which was looking at specific genotypes of families that we isolated from our chambers and grew in the common garden at Bryn Mawr College. We subjected them to nitrogen and carbon dioxide in a place where they're flooded more often.
We were able to track how they grew over the growing season. I had the pleasure of making sure that it was running properly, so I would check on it every so often. It seems like they're getting really interesting results as they're also looking at microbial communities, greenhouse gas emissions, and allocation between root and shoot ratios. I'm just really excited to see where that ends up going.
Jess: Sophia, are you going to grad school at Bryn Mawr?
Sophia: Unfortunately, Bryn Mawr does not have a grad school program for biology majors. However, I am in the process of applying to a couple grad schools, so hopefully I'll be continuing to look into biogeochemistry, staying in wetlands, but we'll see where I end up going. I'm really excited, and my work at the Smithsonian opened my eyes up to a new world and a new ecosystem that I'd kind of been overlooking.
Jess: So are you going to be trying to stay in environmental sciences or switching into a different field?
Sophia: It's really funny because a lot of the programs, they're all under like different names, but I'm still working with wetlands and I would still be doing some sort of biogeochemistry, whether it's direct fluxes or microbes or plant fungi interactions. It's interesting the variety of projects and how even though I'm sort of looking in like the same general area, they get called different things. I would still lump them in as environmental science, climate change science. That's where I want to stay. That's where I want to continue. I think it's one of the most important things scientists should be looking at at the moment, considering our environments are rapidly changing all around us, we need to figure out how they're doing it and how we could help.
Jess: I remember from your poster, Sophia, that you had found that the soil microbes were different between plots within your experiment, and you found that the community was less diverse over time.
Sophia: It's more so talking about the plants that are rapidly evolving. We are finding that a certain group of replicates that are dominated by a specific genotype have higher methane emission rates, and we are wondering what could be going on. They're very closely related to each other. They are under the same genotype. We are hypothesizing that it could be that genotype is responsible for altering biogeochemistry, causing for higher methane emissions and higher carbon dioxide emissions due to its interactions with the soil. So that's something that we're still exploring, but that's our primary hypothesis at this time.
Jess: I thought that was fascinating, that their genes became less diverse over time, and wondering why that happens.
Sophia: I believe part of it is which plants are responding better. The chambers are on the Phragmites invasion front. They are competing with each other and they're competing with the native plants to take up space. That's the name of the game, is like who can take up the most space. Some genotypes respond better to nitrogen and they produce more runners. They allocate more of their energy to above ground biomass, meaning they can grow taller and so they can reach the sun and they can get more of the nutrients that they need to grow and perform well as a plant.
So those ones in chambers with enriched nitrogen, you'll mostly find that those are the plants that have survived over time because they are better at reproducing. They are better at spreading out. They're better at taking up the resources in comparison to other plants that might not respond to nitrogen. And we're seeing some similar things happen in the CO2 chambers, although they're responding differently because CO2 promotes different things in Phragmites. But it's a similar sort of thing of the genotypes that are best adapted and are most responsive to these treatments are the ones who are doing better. We're seeing them take over in certain aspects. And it's just kind of like, luck of the draw to some extent, of these were the genotypes we had that were on this front. And then these are the ones that we're finding of that small sample of who's responding best.
Jess: So it's more like you put a box around a plant and the plant couldn't get out, so now you've created this world where only this plant exists. So, it's going to do the best to out-compete whatever else happened to get inside that microcosm.
Genevieve: It's kind of cool if you look at these chambers that when they were started in 2011. We had 12 chambers, they all had under 10 phragmites stems in them. In 2025, people would go there and say, “Oh, that must be an elevated CO2 because it's completely stuffed.” You can't really find anything else in there. The phrag is moving pretty far into the marsh, there definitely is more phrag now than when we started, but we still have other species. It's basically this one genotype in the CO2 chambers. Evolution at work!
Jess: Yeah, evolution! Is there a similar thing, Genevieve, with SMARTX, where there's a lot of biodiversity because it's so warm and the microbes are replicating faster or proliferating faster?
Genevieve: The plants, there is more biomass in the warm plots. What we don't know is whether the genotypes are shifting. All the microbial data we've done is looking at more RNA than DNA. That's kind of one thing we're trying to switch to focusing on - understanding how the above ground plants are affecting the biosphere and the microbes.
Jess: Insects are probably outside your wheelhouse, but is there a difference in like the amount of mosquitoes or other critters in the warmer plots?
Genevieve: I think we get like more snakes and frogs staying at the warmer plots.
Also, there's all these pumps that deliver the CO2 system to 68 CO2 chambers we have on the marsh. Those pumps are in some little sheds and the snakes will go in there. We don't see a big change in insects, probably mostly because the plots are open.
Sophia: You definitely do notice a difference in the Phragmites plots. They're kind of chambered off except for the top. Aphids thrive in places where there's enriched nitrogen. They go crazy. They're all over the plants. When we're counting and measuring phrag in census, it's just rain of dead bugs all over you. And it's the worst feeling. I can't fault them for being really good in a certain type of environment.
We definitely do notice that certain bugs do better. They're more prevalent in certain plots, and we think that's partially due to the treatment. We can't say for certain, but it seems like they really do like the Phragmites in the nitrogen-enriched plots. I can't say for the other insects, but there's a ton of stuff out there. I can tell you that it's really beautiful, which is why I love working there. And that's something I do like about SMARTX, is nothing's raining on my head, except for rain.