What Lichen Tell Us About Ecology, Air Quality, And More

Ira is joined on stage by experts in Portland, Oregon, to talk about the amazing world of lichen and their role in a changing climate.

Speaker names marked ? are inferred from speaking time and the show’s known hosts — they are not voice-verified.

• 0:00Ira Flatow?

  Science Friday is supported by MathWorks, creator of MATLAB and Simulink software for technical computing and model-based design. MathWorks, accelerating the pace of discovery in engineering and science. Learn more at mathworks.com.

• 0:19Speaker 01

  Did you ever notice the lichen growing on the surface of trees while you're on a hike? They're actually more important than you might think.

• 0:25Speaker 02

  If we lost some of the lichens in our forests, the casual observer might not notice, but the forest would notice.

• 0:32Speaker 01

  It's Thursday, January 9th, and you're listening to Science Friday.

• 0:40Speaker 01

  I'm Sci-Fri producer Dee Peter Schmidt. Today, we're listening back to a live event Ira Flatow taped near the end of last year in Portland, Oregon, a place where lichens are everywhere. Let's listen.

• 0:52Ira Flatow?

  This is Science Friday. I'm Ira Flatow, live with OPP from the World Forestry Center in Portland, Oregon.

• 1:06Ira Flatow?

  Thank you. You know, we can decide wherever we want to go to. We take the show on the road. And when we come to a place like Portland, we have to think, what can we find there that is unique? That we can't find anywhere else in the country? And who are the local experts who can help us see the world in a different way? So you look around at the towering trees and you say to yourself, hmm, why don't we go into the woods? And that's what we did. And we went into the woods and we decided to explore the very often overlooked world of lichens. A lot of people don't know what lichens are. They are a remarkable fusion of fungi, algae, other tiny bacteria,

• 1:51Ira Flatow?

  and they thrive in the misty forests of the Pacific Northwest. And from their crucial role in ecosystems as indicators of air quality to their striking colors and forms, we've really taken

• 2:05Ira Flatow?

  A lichen.

• 2:08Ira Flatow?

  I have never heard of this joke before. I apologize. So, we're going to be joined by the few people who can tell us all about them. And let me welcome them to the show right now. Right on my left is Hannah Prather, postdoctoral researcher and visiting assistant professor of biology at Reed College, where she teaches about the relationship among lichens, host trees, and the surrounding ecosystem. Welcome to Science Friday.

• 2:34Speaker 03

  Thank you.

• 2:40Ira Flatow?

  Jesse Miller is lead botanist for the Washington Natural Heritage Program, where he provides guidance for rare plant conservation efforts. That sounds cool. And studies effects of altered fire systems on plant and lichen communities. Welcome to Science Friday. Thanks, Sarah.

• 3:01Ira Flatow?

  I'm going to start with you. Hannah, tell us how you got interested in lichens, because I was out there with you today, and you were just in your, you were in your element, as we said.

• 3:11Speaker 03

  Yeah, this is true. Oh, such a great question. You know, when I started in graduate school, I started climbing trees. And there's kind of a lot more to that story. But as I was up in these big tree canopies here in the northwest, some of our towering Douglas fir, I started to notice these little plants, or what we now know as lichens, that were occupying this really incredible three-dimensional space. And I think it was sort of through that connection from the canopy to seeing the things that were thriving and living up there, that I really had a lot of curiosity to ask more questions about those organisms.

• 3:45Ira Flatow?

  Very interesting. And Jesse, as I said, you help guide how rare plant conservation happens in Washington and Oregon. And how do lichens fit into that picture?

• 3:57Speaker 02

  Yeah, well, lichens have been overlooked for a long time, relative to animals especially, but plants as well. We just haven't given very much attention to the rare lichens, the lichens that are perhaps even on the edge of extinction. And so, one of my personal and professional missions in life is to try to bring more attention to our endangered lichens. So, that's been a focus of mine, especially for the last couple of years, since I've been in Washington.

• 4:24Ira Flatow?

  Okay, so, let's begin by helping us to understand lichens' ecological niche. I mean, they have one, right? And, of course, we say "they," and you were telling me, Jesse, the plural of lichen is "lichen," right?

• 4:40Speaker 02

  Exactly.

• 4:41Ira Flatow?

  That's the correct way to say it. People get it wrong?

• 4:42Speaker 02

  Yeah, people say "all the lichen out there," like it's some amorphous mass, but there are a whole bunch of different lichens out there, and we need people to understand that. It's very important.

• 4:52Ira Flatow?

  And why are they important? What is their niche in nature?

• 4:54Speaker 02

  Sure. Well, lichens play a lot of important roles in ecosystems. For one thing, a lot of animals use lichens as a food source or nesting material. There are all kinds of invertebrates that live inside lichens. But lichens also play roles in nutrient cycling, they stabilize soil, they play roles in hydrological dynamics. So, if we lost some of the lichens in our forests, the casual observer might not notice, but the forest would notice.

• 5:24Ira Flatow?

  And I know that you focus on lichens that are, quote, "on the fringe," right? What do we mean by that?

• 5:32Speaker 03

  Yeah, well, my background, my PhD research was looking mostly at urban lichens. So, how these communities of lichens and these tall tree canopies, how they're being affected by sort of the urban condition of urbanization, the transfer of air pollution, things like this. A second part of my work took place on the western Antarctic Peninsula, a place of rapid warming on the globe. And so, we were looking at lichen and bryophytes, mosses, and those communities, and how they're changing really dramatically with warming effects in that area.

• 6:03Ira Flatow?

  Are they significantly different from the kinds we would find around here? In Oregon, if you looked at me, you'd say, "Oh, yeah, that come from the poles," you know.

• 6:10Speaker 03

  Certainly. I mean, Antarctica's a beautiful flora. There's certainly things that are endemic only to Antarctica, but there's also cosmopolitan species that occur everywhere. So it's kind of an interesting blend.

• 6:21Ira Flatow?

  We were out in the forest, you were showing us lichen, and people were asking, "Could this lichen grow differently if there weren't air pollution? Does air pollution affect the growth of lichen?"

• 6:31Speaker 03

  Yes, and many of us might have heard of this sort of, lichens can be this canary in the coal mine, right? They're these bio-indicators, something that's naturally in an environment, but can also give us a lot of information about the condition of that environment. So we know that lichens respond pretty quickly to things like air quality, pollutants, and one of the main ways that we see this is in their morphology, so the size of the lichen. Lichens don't have protective mechanisms like vascular plants do. They don't have a waxy outer surface or stomata that can regulate sort of gas and surface exchange. And so because of that, they're these little sponges in the environment, so when things land on them, they actually absorb that fairly easily if they're hydrated. So the morphology

• 7:16Speaker 03

  is kind of one way that they can limit the surface area exposure to pollution. So often in urban areas, we will see lichens that are tolerant of urban conditions. And if they aren't tolerant, they might shrink their size down so that they have less of that surface area touching the pollution.

• 7:33Ira Flatow?

  Jesse, you're nodding in agreement.

• 7:35Speaker 02

  Yeah, absolutely. And when you go out to a forest with really high air quality, you know, many miles out of the city, you see a whole suite of lichens that you won't see in the city or in any other more polluted areas. So it's really... And then here in urban areas, we actually see lichen species that are indicators of air pollution, species that actually become more abundant in polluted areas. So there's a whole story to read on the landscape out there.

• 8:02Ira Flatow?

  Yeah, and I know that you study the effects of wildfires on lichen, right? I mean, does that mean just the heat effects, or is it the smoke and everything that they leave behind?

• 8:11Speaker 02

  Yeah, it's a lot of different effects. So there are direct effects. I mean, lichens often burn up in fires. That's one of the most obvious conclusions, but not a huge shocker there.

• 8:25Speaker 02

  But you know, never be afraid to prove the obvious.

• 8:28Ira Flatow?

  I hate it when that happens.

• 8:30Speaker 02

  But there are all kinds of indirect effects as well. Fires change the landscape. They might change a forested landscape to an open grassland. And all those forest lichens are not going to recolonize unless a forest grows back some decades or centuries later. But it's really important to recognize that there are fire can burn in many different ways. We have what we call low severity fires, fires that don't remove most of the trees and other vegetation, and high severity fires that do remove most of the vegetation. And high severity fires typically have much stronger effects on the lichens.

• 9:07Ira Flatow?

  Hannah, do people walk past lichens and just never know that they're looking at them?

• 9:12Speaker 03

  Oh, absolutely. Lichens are really good at being very cryptic, right? And so they often are sort of these kind of scummy, scuzzy things that are on your roof or your driveway. You've probably all have tried to scrape them off. I won't judge. But yeah, so they occupy a pretty unique part of the landscape. They like to grow on other things. So we'll see them on trunks of trees, on rocks, even on buildings, maybe even on your car if it's been parked in the northwest for a while. So it's very common that people overlook these little organisms.

• 9:44Ira Flatow?

  Well, what makes them different from just moss that we see growing all over the place? What makes it not a lichen?

• 9:51Speaker 03

  Yeah, good question. So mosses and lichens actually like to hang out in the same types of habitats. So especially in the northwest, we have a lot of moisture in our systems. So we see both often really together. So one of the sort of key indicators I always kind of tell my students when we're talking about the difference between lichens and mosses is that mosses are ancient plants. So they always have a stem and leaves. That's one good way to notice them. They also have a little bit greener of a color overall versus lichens are built of fungi. So they often have these really different morphologies that can look a lot of different ways, flat like a leaf or sort of threaded like a little shrub.

• 10:29Ira Flatow?

  Do they share the same space as the moss?

• 10:32Speaker 03

  Oh, absolutely, yeah.

• 10:33Ira Flatow?

  So is this like a symbiotic thing going on there?

• 10:36Speaker 03

  No, I wouldn't say there's any sort of symbiotic relationship. I would say it's more of they thrive in the same types of environmental habitats. There is a lot of work in the northwest looking at stratification of these species across in really tall canopies. For example, we used to have a research canopy crane located here in the northwest where we did a lot of the preliminary research, looking in tall trees to see how these things stratify with gradients of light and moisture. And so what we know is that mosses often like to be in the moisture low layers, low light layers of a canopy or of a forest. And lichens do kind of like to be in the higher bits where there's more high light and a lot of drying as well.

• 11:16Ira Flatow?

  And also, do we find them on rocks? Can you see, Jesse, you see them on rocks everywhere?

• 11:22Speaker 02

  Oh, absolutely. Some of the very best lichens are on rocks.

• 11:25Ira Flatow?

  Is that right?

• 11:26Speaker 02

  I mean, lichens will grow on almost anything that holds still. So, rocks, trees.

• 11:32Ira Flatow?

  People.

• 11:33Speaker 02

  You know, it probably means you need to live a more active lifestyle if that happens.

• 11:39Ira Flatow?

  Is that right? So because sometimes you'll see, you go through and you see these rocks in a forest and they have patches on them, different colored patches. Or is that what lichens are also sort of flat, not these big raised leafy things?

• 11:54Speaker 02

  Yeah, and those are crustos lichens, those really flattened lichens that are just totally sunken into the substrate. And those are actually some of the most challenging lichens to identify. Those are the lichens that keep us up at night.

• 12:08Ira Flatow?

  Those are the kinds that people are power washing off their rocks sometimes.

• 12:12Speaker 02

  Yeah, you know, some people try to identify the lichens, other people just try to power wash the lichens. That's the world we live in.

• 12:19Ira Flatow?

  Well, why should we care? And seriously, why should we care about lichens? They're so small, a lot of people don't see them. Why should we care so much? Let me start with you.

• 12:28Speaker 02

  Sure. Well, you know, a lot of people don't even think about lichens or notice lichens in their day-to-day life, but lichens play all these roles in ecosystems that we don't see. And ultimately, we're all dependent upon the ecosystems around us. So one of my favorite examples is old-growth forests in the Pacific Northwest are inhabited by flying squirrels that eat lichens as a major part of their diet. And flying squirrels in turn are eaten by spotted owls, which are one of our great animals in the conservation history of the Pacific Northwest. So if we lost a lot of our forest lichens somehow, it would affect this whole food chain. And people see the squirrels and they see the owls, but they may not notice the lichens.

• 13:14Ira Flatow?

  We'll be right back after this short break. This is Science Friday from WNYC Studios.

• 13:25Speaker 04

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• 15:35Speaker 04

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• 15:50Speaker 05

  Are all lichens equally safe to touch and handle? And if not, what are the features you look for that might say, "Stay away"?

• 15:59Ira Flatow?

  Are there poisonous lichens?

• 16:02Speaker 03

  Boy, okay, I'll do my best. Jesse, you can jump in.

• 16:07Speaker 03

  I'm almost afraid to go on statement here.

• 16:12Ira Flatow?

  No one's listening, so it's okay.

• 16:13Speaker 03

  Most lichens are safe to handle. I think would be a safe assumption. There are a few lichens that have toxic qualities to them. One of those is the wolf lichen. It's a chartreuse lichen that's often on the east side forests that we'll see. And it's just known to have some poisonous qualities, so you wouldn't want to ingest it, or maybe touch it a lot and touch your mouth. But for the most part, lichens are really friendly to interact with. Yeah, if you find them on the ground, you can pick them up. There's nothing... Can you think of any other not overlooked?

• 16:46Ira Flatow?

  So it's not like possible poisonous mushrooms that you might be thinking of?

• 16:49Speaker 03

  Oh, no.

• 16:50Ira Flatow?

  No. I think that's probably what people were thinking of. Yes, thank you for that question. Next.

• 16:55Speaker 06

  Well, yeah, actually, on the concept of picking up lichen, I'm a nature and forest therapy guide, and we do a lot of texture stuff. And people like to bring textures back with them. And they often bring back lichen, whether it's still attached to a stick or that they found on the ground. Are those alive?

• 17:14Ira Flatow?

  Yeah, we saw a lot of stuff today in the forest. A lot of lichens on sticks that were falling down. Are they alive?

• 17:22Speaker 03

  The answer would be yes. I mean, assuming that they are in... Lichens can die. They can start to sort of degrade back into the environment. Often those look, like Jessie had mentioned, either bleached, so they've lost the algal component, or they're a little bit necrotic and reddened, meaning that the fungal partner is starting to die. And that can happen fairly quickly if it's in a really wet... They fall on soil and they can kind of start to decompose back. But typically, things that are epiphytic, they like to grow on tree branches or up on other surfaces. If you bring those inside, they probably are still alive if they're hydrated. They can go into that sort of dormancy period if they're dry. And they can do that, again, for periods of time depending on the species.

• 18:06Ira Flatow?

  We were in the forest watching... You found a tree branch on the ground, and I have never seen a scientist get so excited about finding a tree branch. What makes that so special about that?

• 18:17Speaker 03

  Oh, if you're a lichenologist and you find a branch from the canopy on the ground, it's like total gold, like you've hit the jackpot. Because it's really giving us this nice snippet of what we're seeing up overhead that otherwise would be really hard to access. You'd have to use ropes or some other technique to get up there. And so just on that one branch, Ira, we found what? Almost eight different species, just on a very coarse look. So there's probably many more.

• 18:42Ira Flatow?

  And you were happy a dog hadn't come along and just run off with the branch?

• 18:45Speaker 03

  Yes.

• 18:46Ira Flatow?

  Yeah, I get it, yes. Next question, please.

• 18:49Speaker 07

  I'm curious, as we have a room here of people who are interested in lichen, what we can personally do to help encourage lichen growth and conservation. I think about when I am out in nature and I'm trying to not walk off the trail and thinking about what you said about lichen. Anchoring on soil to stabilize it. I'm also curious about cryptobiotic soils, but curious about personal responsibility, how we can help lichen and how to encourage its growth and not accidentally kill it, things like that.

• 19:28Ira Flatow?

  Any recommendations? Should you avoid walking on the lichen if you see them in the forest?

• 19:36Speaker 02

  Yeah, as far as those crusts that grow on the soil, we have a saying, "Don't bust the crusts." So yeah, don't walk on those crusts. That's one smart move. But I think more broadly, just learning a little bit about lichens and learning to identify some common lichens in your area is one great step forward to being a friend of the lichens and helping them. But one much more specific thing I'd suggest, the U.S. Forest Service is working on revising its umbrella management plan for all the forests in the west, the northwest, or in the northwest, the Northwest Forest Plan. And there are periodic opportunities for the public to comment on this.

• 20:20Speaker 02

  And one big question, so for many years, the Forest Service has safeguarded, or tried to safeguard, many of our rare lichens. It's kind of up in the air whether that policy will continue. So I'd encourage everyone to put in a comment and say you want to see our rare lichens continue to be a priority for management.

• 20:37Ira Flatow?

  Yeah, it takes public interest.

• 20:39Speaker 02

  Absolutely.

• 20:40Speaker 05

  Before I ask my question, I have a lichen joke. A fungus and an algae took a lichen to each other, and now their marriage is on the rocks. So when I taught in Alaska, where glaciers had receded, we told our students that you could age, how long ago were the ice had moved back, especially places where there wasn't photographic evidence, because certain species of lichen would grow in the rocks at a certain rate. I was wondering if you could speak to that.

• 21:22Speaker 03

  I'm not sure what else to say. It's a really cool thing. I've worked in polar ecosystems, and the lichens are incredible. I think it's a really... It's been a really neat part of my work to kind of look in areas of recent recession and see what types of species are there, what types of role they're playing, how they transform soils early on in those processes. So it's pretty fascinating.

• 21:45Ira Flatow?

  Is it surprising to see how resilient they are to live in that kind of climate?

• 21:49Speaker 03

  Oh, absolutely, yeah. I think some of the interesting changes on the Antarctic Peninsula are just the change from snow to rain. And so a lot of those species aren't able to kind of handle having more liquid moisture.

• 22:03Ira Flatow?

  Interesting. Yes, step up.

• 22:05Speaker 06

  Okay, so I saw a video once upon a time of two lichen experts that came here to Oregon, and they were at the waterfront here in Portland and also in the gorge, talking about signs of, or like symptoms in lichens of an unhealthy air environment. So if you know anything about that, could you get into some of the basic signs of how to tell your air quality?

• 22:31Ira Flatow?

  Yeah, how do you tell air quality from the lichens?

• 22:35Speaker 02

  Well, I'd say one thing to notice is just the size and stature of the lichens. In polluted places, the lichens are going to be a lot smaller. But we also have a lot of lichens that are orange in color that grow in polluted places, and these are nitrophiles or nitrogen-loving lichens, pollution-loving lichens. So when you see just a tree that's covered in orange lichens, for example, that's a sign you may be in a fairly polluted place. And when you see a tree that's covered in big, draping, three-dimensional lichens, that's a sign that you might be in a place with better air quality.

• 23:16Ira Flatow?

  Interesting. It's good to know that. Yes, please.

• 23:19Speaker 06

  So I've noticed at the Home Depot parking lot near my home, where they do a lot of leaf blowing, the trees in the parking lot are just covered in lichen. And I've always wondered if it's because of the leaf blowing. It's blowing the lichen particulates up and sticking them on to the trunk. Do you have any thoughts?

• 23:39Ira Flatow?

  Wow, what an observation.

• 23:40Speaker 02

  I think you could set up a really neat experiment to test this.

• 23:45Ira Flatow?

  There's grant money here for that.

• 23:47Speaker 06

  I fell in love with them about 12 years ago, and just I'm obsessed with them, so.

• 23:53Ira Flatow?

  Could that be happening? I mean, serious? Could that be an unintended consequence of leaf blowing? And is it a healthy thing to get more of them up into the tree?

• 24:03Speaker 02

  I think it's conceivable that there could be lichen propagules getting into the leaves and then blowing back onto the tree. Yeah, that would be a great science or nature paper, I think, if we could prove that.

• 24:19Ira Flatow?

  Talk about citizen science.

• 24:20Speaker 02

  Yeah.

• 24:21Ira Flatow?

  Does everybody get it right? You want a citizen science project?

• 24:23Speaker 02

  But we actually are still working on developing methods for, you know, I mentioned this idea that we perhaps should be establishing new populations of some of our rare lichens. And figuring out the exact methods we would use to do that remains kind of an open question. So I'll add leaf blowers to the stack of ideas.

• 24:40Ira Flatow?

  Wow, wow. Yes, next question, please.

• 24:45Speaker 06

  So when I go to any bookstore and I go to the natural science section, there are dozens, if not hundreds, of books on fungi, but like two or three, if any, on lichen. So I want to know, why does it seem like there's such a deficit of research and cultural significance placed on lichen as opposed to fungi?

• 25:07Ira Flatow?

  Yeah, it needs better public relations, lichen. I mean, seriously, right? I mean, people don't talk about it. They talk about the moss. And that gives me, brings me to my blank check question I ask a lot of my guests. If you had a blank check and you wanted to spend it on researching or doing, getting public, how would you, how was the best way to spend all that money? Is it, is it studying lichens in a certain way or publicity for it? Or, Jesse, let me ask you first. What don't you know that you want to know that you could spend that money on?

• 25:43Speaker 02

  Yeah, so we know that there are a lot of lichens that are associated with old growth forests in the Pacific Northwest, but we've, of course, lost most of our old growth forests, which used to cover the landscape. So one question I wonder about is, how suitable are some of our more mature second growth forests? And what can we do to help bring about more old growth character in some of our forests that aren't quite old growth, but are nice old stands of second growth? And also doing experiments to try to establish new rare lichen populations in some of those stands. That would be a priority for me.

• 26:19Ira Flatow?

  And how would you spend some money? Like, given your blank check, what would you spend it on? Anyway, anything that involves working with lichens?

• 26:28Speaker 03

  Yeah, I hate to piggyback on Jesse's, but I think there's a real, I think just living in the northwest and loving our forests and really seeing the beauty of an old growth forest and kind of the loss that we're looking at with increasing wildfire and the loss of Opal Creek, oh my goodness. I really think that there's some interesting research around these types of questions that Jesse is posing. Can we somehow accelerate those conditions back to old growth? Can we somehow bring in lichens and propagate or attach them into canopies and help like reestablish that biodiversity? I think there's a lot of interest in that.

• 27:04Ira Flatow?

  Interesting, yeah. Okay, next question, please.

• 27:08Ira Flatow?

  I was wondering, since lichens are three or more organisms, how do you begin to like sort them taxonomically? And describe that like evolutionary relationship that some of them might have?

• 27:25Ira Flatow?

  Jesse, want to begin?

• 27:26Speaker 02

  Yeah, great question. How do we define species for organisms that are inherently composed of multiple species? So the names we actually use for lichens, the scientific names, actually refer to the fungal partners. And part of the reason for that is because pretty much every unique lichen out there is a different fungus, but many of them share the same algae. So that's why we use the names of the fungi rather than the algae. But there are some interesting cases where that system doesn't quite work perfectly. There are cases where the same fungus can partner with two different algae and form two totally different lichens. But because we name them after the fungi, we call those two lichens the same thing.

• 28:10Speaker 02

  So it remains an imperfect science.

• 28:13Ira Flatow?

  Do we need different names for them?

• 28:15Speaker 02

  Perhaps. That's something that's been talked about in the lichenological community. And I think it'll be interesting to see where we are in 20 or 30 years.

• 28:24Ira Flatow?

  Lichenological. I like that. Like that, yes.

• 28:29Speaker 06

  The whole idea around symbiosis, I honestly find really romantic. And the way you're even describing- Those relationships and how they meet each other and how they have babies and all that. So I'm wondering about the, I know this is different than other people's questions, but the sense of is poetry or art or the the elements of that relationship inspiring some creative worlds?

• 28:54Speaker 03

  I will add, just on your romantic notion, that I did have a final project for my lichens course last year was a lichen outreach project where they had to spread the word on lichens and what was so great. And I had some students put together a dance about the symbiosis, the coming together of the partners, and it was actually really incredible.

• 29:15Ira Flatow?

  Wow, where can we see that?

• 29:18Speaker 03

  It's actually, I think, posted on the Reed Biology webpage.

• 29:21Ira Flatow?

  There you go. Soon to be a major motion picture. Okay. Question?

• 29:27Speaker 06

  I'm wondering about whether or not we see any lichens in the fossil record and if we have any ideas about their history of evolution, kind of a different turn from the the poetry, a little bit more hard science there.

• 29:42Ira Flatow?

  Good question.

• 29:43Speaker 06

  But they don't have any hard parts. Do we see them? Like, do we have any ideas about when and how they might have evolved?

• 29:48Speaker 02

  Great question. So my understanding is that there are only about 150 individual lichens that are that have been found as fossils. So they really don't fossilize very well at all compared to a lot of other organisms. So that's that's one reason why reconstructing their ancient evolutionary history has been really difficult. But we do currently believe that lichens are hundreds of millions of years old, so they do go back a really long ways.

• 30:14Ira Flatow?

  Wow, that is, that's good to know. Yes, sir. Hi. I'm I'm really interested in how cities grow and change, and I'm really wondering whether there's any lessons to be learned by

• 30:28Speaker 02

  Looking at our lichen communities and how they grow and adapt to changing environments that we can apply to the way we design our neighborhoods in our cities. Well, great question. I think one cool example is after the Clean Air Act was passed, some lichens that were no longer growing in urban areas were actually observed to come back and recolonize urban areas because the air quality had improved so much. So yeah, I think it's wonderful to use them as an environmental indicator as conditions change over time. Absolutely.

• 31:03Ira Flatow?

  That's great. All right, one last question for the evening for the panel here. What one thing, what one message, what one idea do you want everybody in our audience to take home tonight about lichen? I'll start with you.

• 31:22Speaker 03

  Well, I, you know, one thing that I think that has really been meaningful for me in working with students and lichens is probably that just it's a great connection to nature and they're so ubiquitous. So you can go right outside your door on your city street or in a city park and find many lichens. So I really want to encourage people to just get to know the lichens in your neighborhood, get to be outside and enjoy those. This is the best lichen viewing time because we're having sort of this stormy, wet weather. So it brings down lichens out of the canopy. It brings down branches. And so it's a great way to just connect with nature, find some in your area and learn about them.

• 31:59Ira Flatow?

  Thank you, Hannah. Jesse, what do you think?

• 32:02Speaker 02

  Well, we, we really are living in challenging times. We are experiencing a biodiversity crisis around us and we have to make choices collectively about how we want to address this. So my closing message to everyone is please vote.

• 32:17Ira Flatow?

  That's Jesse Miller, Lead Botanist for the Washington Natural Heritage Program, and Hannah Prather, Postdoctoral Researcher and Visiting Assistant Professor of Biology at Reed College. They spoke with us onstage at the World Forestry Center in Portland, Oregon, in an event we produced with OPP. Special thanks to OPP's Jess Burns and SciFries Diana Plasker.

• 32:41Speaker 01

  That's all the time we have for today. Lots of folks helped make the show happen, including Rasha Ridi. Sandy Roberts. Shishana Buxbaum. Danielle Johnson. Coming up tomorrow, we've got really big Science Friday news to share with you. You won't want to miss it. Stay tuned. I'm Sci-Fry producer Dee Peterschmidt. Thanks for listening.