‘Underground Atlas’ Shows How Vulnerable Fungal Networks Are

FLORA LICHTMAN: This is Science Friday. I’m Flora Lichtman. When you think about the planet’s top conservation priorities, you might think about biodiversity hotspots, like the Amazon rainforest or the Galapagos Islands. Or maybe you think of animals, like rhinos or Wright whales. But my next guests have something else in mind, a kind of underdog in the conservation world, something that supports life on Earth, but that most of us probably don’t think about. An invisible ecosystem beneath our feet– fungal networks.

They say these underground fungal filaments are critically important to us and our planet, and we should pay them some respect. Why? Here to tell us are my guests, Dr. Adriana Corrales, forest ecologist in Bogota, Colombia, and Dr. Michael Van Nuland, ecologist in Portland, Oregon. Both are researchers with SPUN the Society for the Protection of Underground Networks, which we’re going to hear more about. Welcome to you both to Science Friday.

MICHAEL VAN NULAND: Thank you for having us.

ADRIANA CORRALES: Yeah, thank you so much for this invitation.

FLORA LICHTMAN: Adriana, let’s start with you. Why should I care about the fungus underneath my feet?

ADRIANA CORRALES: Wow well, mycorrhizal fungi, or soil fungi in general, are megadiverse. Soils are megadiverse ecosystems. And mycorrhizal fungi specifically, we believe they support life on Earth. Because plants have, in many cases, an obligatory symbiosis with mycorrhizal fungi, and plants wouldn’t be able to really survive, or have colonized terrestrial ecosystems, without these fungi. So we just believe they are the basis for life on Earth.

FLORA LICHTMAN: Wow.

ADRIANA CORRALES: Basically.

MICHAEL VAN NULAND: They do all sorts of incredible things, like Adriana was saying. They partner with the vast majority of plants. So any plant that you see from where you’re sitting right now, there’s a good chance that it has a fungal partner attached and wrapped around its root system. And the fungi is out in the soil building these hyphal networks. And through their building of this fungal infrastructure, they’re helping stabilize soil. They’re helping gather nutrients that the plant needs to grow and survive and reproduce.

They’re interacting with all the other diversity that’s in the soil and helping soil food webs run. And in partnership with plants, they help draw down lots of carbon. As the plants are photosynthesizing, they’re sharing those carbon resources with their fungal networks. So they’re also– we’re realizing they’re also becoming really critical to our global climate story and our global strategy to find climate solutions, because of their potential for this large carbon drawdown.

FLORA LICHTMAN: These fungi sound like givers. What are they getting from these relationships?

MICHAEL VAN NULAND: They are getting carbon. And they’re also getting a nice environment to live with a partner. They could be out on their own, trying to mine for resources and get carbon and sugars from the soil environment. But soils are a tough place to live. One of the co-authors on our new study, Merlin Sheldrake, describes soils as a crowded rotscape.

FLORA LICHTMAN: [LAUGHS]

MICHAEL VAN NULAND: So they’re not the most hospitable places to live. And so by–

FLORA LICHTMAN: That is a good band name.

MICHAEL VAN NULAND: It’s crowded rotscape– I was thinking about that the other day. It is a great band name. They’re just harsh places to live. And so by partnering with plants and getting access to the carbon that the plants are photosynthesizing, it’s a little bit of a shortcut. But it’s a way for them to live a little bit more comfortably in the soil and do some really amazing things.

FLORA LICHTMAN: How should I imagine these underground networks? Can you paint me a picture?

MICHAEL VAN NULAND: Yeah. One way we describe them is a circulatory system. So if you imagine the veins and arteries in your body and how they are weaving their way down your arms or down your legs and providing oxygen to key parts of your body, fungal networks are the circulatory system of soil. So they’re these networks that grow through the soil matrix.

They grow underground. They grow in these amazing, branching patterns. And then not only are they visually very beautiful. Functionally, they’re moving tons and tons of cellular material through these highway networks. So they look like really complicated branching root structures underground. But they’re not roots. They’re fungal tissue.

FLORA LICHTMAN: Are they microscopic? Are they– could I see them with the naked eye?

MICHAEL VAN NULAND: So some of them you can see with the naked eye. Sometimes they fuse together and create these big, thick fungal rooty-type structures. And sometimes if you’re gardening or digging around in the dirt, you might peel back a layer of leaf litter or something and you’ll see these really thick white threads weaving its way right at that surface. So that is a–

FLORA LICHTMAN: Yes.

MICHAEL VAN NULAND: Yeah, so that is a fungal network. That might not be a mycorrhizal one. But those are the types of networks that we’re talking about. And just a mind boggling amount of fungal tissue creating that network is underground at any one time beneath your feet.

FLORA LICHTMAN: Mm. SPUN, the Society for the Protection of Underground Networks, just unveiled this huge map of these networks. Where did you find the hotspots, the places that you thought were the most important?

MICHAEL VAN NULAND: So we predicted hotspots of mycorrhizal fungus networks in these really interesting places, and some unexpected places to us. And we found hotspots in lots of different tropical forests, but surprisingly not the Amazon rainforest. We actually found hotspots just outside the Amazon forest, in the savanna, the Cerrado in Brazil, and some of these hot, humid grasslands in South America. It was still really surprising to us that those were the hotspots for this type of mycorrhizal fungi, and not places that we think of, like the Amazon rainforest.

ADRIANA CORRALES: One of the things that I am more excited about these maps, is the tool that we designed, the underground atlas. Because that could be a great connection for everyone, even if you’re an ecologist or you are into fungi or no, to really look at the diversity in your area. Are you living in a hot spot or not? What is the diversity of these fungi in your backyard? And if you are into mushrooms, how many of those species have you observed or not? So I think that that’s a very cool tool that every person can use to really connect with these maps and explore the diversity in their local areas, for example.

FLORA LICHTMAN: You can find a link to this on our website at sciencefriday.com/spun. So these hotspots are based on data collected from field biologists. Adriana, take me into the field. What is it like to do this kind of fieldwork?

ADRIANA CORRALES: Well, yeah, it depends where you are located. Here in Colombia, for example, I have worked on collecting locations in the Andes, in the Black Oak Forest, which is an endemic forest of Colombia, which is pretty remote, is cloud forest. There are just small fragments of this forest that are remaining. So you have to fly there and go in these dirt roads to the top of this mountains and collect both the soils, but also the mushrooms, because this is the type of mycorrhizal fungi that produce mushrooms. So yeah, it’s pretty rewarding at the end, to have the samples in your hand and come back with them.

FLORA LICHTMAN: So SPUN is advocating for the protection of these hotspots. What kind of threats are they facing?

MICHAEL VAN NULAND: They face very similar threats to other organisms that folks are concerned about. So climate change is a big threat. The fungi in the soil are not immune to feeling those shifts in temperature, feeling those changes in soil moisture. And then beyond climate change, habitat loss is another key factor.

FLORA LICHTMAN: Yeah, what does habitat loss look like for soil underground?

ADRIANA CORRALES: Yeah, so habitat loss could be seen as deforestation, in some cases. But also, for example, this could look more like soil degradation or exotic species invasive. But I think one thing that could be transversal to all that is soil degradation, because soil is going to suffer when the biomass above ground is destroyed and all those host plants are destroyed. But also when, for example, we put fertilizers in the soil or things like that, so there are chemicals in the soil. So those are super important also for soil organisms and sometimes are not super evident from the aboveground perspective.

FLORA LICHTMAN: Yeah. How many of these hotspots are in areas that are protected?

MICHAEL VAN NULAND: We estimate that less than 10% of overall hotspots that we predict are currently in protected areas. And when we compare that to animal diversity hotspots or tree diversity hotspots, it’s about three times less for mycorrhizal fungi compared to those other protection levels for other organisms.

FLORA LICHTMAN: Hmm. Adriana, does that make you nervous?

ADRIANA CORRALES: Very.

FLORA LICHTMAN: Really.

ADRIANA CORRALES: I mean, it makes me nervous because we are not aware that we are destroying these communities, and most people are not aware of the importance of this fungi for the functioning of our ecosystems. So I think we sometimes give for granted that soils are just going to continue to exist, and to give us all their functionality, or the great services of carbon storage or water regulation or all those things that we use soils for.

FLORA LICHTMAN: Do you feel this is an issue on the radar of conservation groups or governments or activists?

ADRIANA CORRALES: No.

MICHAEL VAN NULAND: Generally, no. Maybe decreasingly so. Certainly not governments, it feels like. Maybe activists a little bit more. I mean, it’s hard. They are invisible organisms underground. They have two really big things going against them to get them into the same level of conversation that we have for other organisms, that we can see and measure and hear. And yeah, that’s just a big challenge.

FLORA LICHTMAN: How do you conserve something that lives underground?

MICHAEL VAN NULAND: The short answer is we don’t know yet. So the research that we just did, we compared those hotspots to protected areas. But we don’t know if you just set up boundaries and call it a national park, is it a national park for fungi? We don’t know the answer to that yet and we’re racing to find out.

FLORA LICHTMAN: This is a question for both of you. So yeah, it’s hard to make people care. What is your strategy to make people care? Adriana, let’s start with you.

ADRIANA CORRALES: I tell people, and I used to tell my students, when you think of a plant, you have to think of fungi and mycorrhizal fungi, because they– fungi are the microbiome of plants.

FLORA LICHTMAN: Oh, I love that. Yeah, of course.

ADRIANA CORRALES: So the root microbiome has tons and tons of fungi, and the plants wouldn’t be able to acquire their nutrients without those fungi. So that’s really eye opening for people, that agriculture depends on these fungi to thrive, and food security is going to depend on the diversity of these fungi and the ability of these fungi to also adapt to new environmental conditions.

MICHAEL VAN NULAND: I mean, part of it is filling a data gap. So folks who work in the conservation and restoration space have not really had the fungal data they need to help them make decisions about which ecosystems to prioritize for protection and those types of things. So that’s one of the ways I feel personally motivated, by just building bigger and better and unignorable data products, to allow them to–

FLORA LICHTMAN: A lot– people can ignore data, Michael. I don’t know if you’ve noticed, but actually, it’s apparently very easy to ignore data.

MICHAEL VAN NULAND: Yeah. And maybe, yeah, that is probably too much of a white whale goal for me, to build the best fungal map possible that is unignorable. But that’s something I should talk to a therapist about, most likely. But part of it is filling a data gap, or at least providing the data to the people who care, who will incorporate it, and measuring the impact of that.

FLORA LICHTMAN: Can I offer a perspective on this?

MICHAEL VAN NULAND: Yeah, absolutely. Please.

FLORA LICHTMAN: I mean, as someone who’s worked to help the public care about science for the last two decades, I’ll just add one more thing to your list, which is, we tend to take action when we have an emotional response. I think you got to make people feel something about all of this.

ADRIANA CORRALES: Yes, I 100% agree. We don’t care about what we don’t know and we don’t love what we don’t know. So it’s super important to just tap into the feelings. And actually many people are getting so excited about this fungi, because for the ones that produce fruiting bodies, they are so beautiful and just eye catching, and people really love them. I have an emotional connection with fungi because I am obsessed with them. And I can see how–

FLORA LICHTMAN: Well, tell me more about that. Why do you have an emotional connection to them?

ADRIANA CORRALES: I just love them. I see them and I just talk to them and I collect them. And I– once I’m in the field and I know a place, I’ve been there collecting several times, and you find a new species that you didn’t see before. And it’s like, oh, my God, where were you before? I never seen you. And it ended up being a new species for science or something. And it’s just so– it’s just the amusement of seeing these organisms that are just so different looking. Because they don’t look like anything else. They just have their own shapes and colors and they are just so striking.

FLORA LICHTMAN: I think in the very beginning of this interview, Adriana, you said that it’s the basis of life on Earth. So what would our world look like without these fungi?

ADRIANA CORRALES: Oh, that’s a big one. This is so cool. Because of course, plants are primary producers, right? But yeah, plants depend on mycorrhizal fungi and mycorrhizal fungi depends on plants. And they cannot live without each other. So when we think about primary producers, and the first step in food chains, you have to think about fungi as well.

FLORA LICHTMAN: Agriculture, trees, the plants that other animals eat, all of that.

ADRIANA CORRALES: All of that, yeah.

FLORA LICHTMAN: When you talk about protecting fungal networks and how important they are, it feels kind of existential. How has studying them changed your perspective?

ADRIANA CORRALES: Studying fungi have changed the way I see plants. For example, I’m a forest engineer and I learned a lot about plants and biomass on wood when I was in school. But understanding the underground and the vast amount of species and carbon and other functions that are there, that we don’t really think very much about, it’s like diving in on something that is completely unknown. There are under 200,000 described species of fungi, and we have predicted 2 or 3 million species of fungi. So there is just so much unknown. And every little step, every little data set that I analyze, is just more information and more to discover.

Thank

FLORA LICHTMAN: You so much, both of you, for joining me today.

MICHAEL VAN NULAND: Thank you for having us.

ADRIANA CORRALES: Thank you so much. Dr. Adriana Corrales is a forest ecologist in Bogota, Colombia, and Doctor Michael Van Nuland is an ecologist in Portland, Oregon. Both are scientists with the Society for the Protection of Underground Networks.

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