Our Universe Revealed, Part 6: A Walk Through South Bend

Episode Topic: A Walk Through South Bend (https://go.nd.edu/0fe630)

How can urban landscapes improve air and water quality, cool neighborhoods on a hot day, and support biodiversity? Watch as Deb Marr Ph.D., associate professor of biology at Indiana University South Bend, explore this question. Urban landscapes are more than backdrops — they reflect our history, knowledge, and affect the health of our communities in fundamental ways. The city of South Bend is working to nearly double our urban tree canopy coverage. In this talk we will explore ways that soil ecology and increasing tree canopy coverage can improve human health, as well as address the complex problems of climate change and loss of biodiversity. Deb will share some early data that we have on ways that soil ecology is affected by landscaping practices, and connections between landscape and carbon emissions.

Featured Speakers:

• Deb Marr Ph.D., Associate Professor of Biology, Indiana University South Bend 

Read this episode's recap over on the University of Notre Dame's open online learning community platform, ThinkND: https://go.nd.edu/49f90d.

This podcast is a part of the ThinkND Series titled Our Universe Revealed. (https://go.nd.edu/6d2a91)

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Transcript

Welcome and Introduction

Speaker 10 0:11

Good evening everyone. My name is Tammy Freeling and I'm the Director of Communications and External Engagement at the College of Science at the University of Notre Dame. As the moderator for tonight's talk, it's my distinct honor to welcome you to a brand new season of our universe Revealed The Our Universe Revealed series includes talks and science. Music and the arts, steam for everyone. We feature current research and creative work being done in our region, and an opportunity to be curious about ourselves, our world, and our universe. This is the third year that the library has graciously hosted our universe revealed, but it actually originated as a physics outreach effort back in September of 2015. Since then, we've grown the series beyond Notre Dame and it has become a wonderful collaboration with IU South Bend and the St. Joseph County Public Library next fall. We'll mark the 10th anniversary of this public lecture series, and we'll have some fun things planned to celebrate that milestone. I hope you'll continue to join us and engage our speakers with your curiosity. Now to kick off this 20 24, 20 25 season of our universe revealed my series co-organizer, Deb Maher, will present tonight's talk. Deb Maher is a professor in the Department of Biology at Indiana University South Bend. She earned a bachelor's degree in science with honors in biology at Binghamton University in New York, her PhD in ecology and evolution at Indiana University Bloomington, and she did postdoctoral work at Vanderbilt University at IU South Bend. She teaches courses ranging from introductory biology to upper level courses in ecology, environmental sciences, and sustainability studies. Her current research projects include studying old growth forests, pollinator and reproductive ecology of an endangered Indiana plant species. And I hope we'll learn what that is. I'm very curious about that one. And projects in urban ecology, which is the focus of tonight's talk. So thank you and join me in welcoming Deb Maher to the stage as she guides us through her talk. Taking a walk through South Bend, how can urban landscapes improve air and water quality cool neighborhoods on a hot day and support biodiversity. Deb,

Speaker 3 2:56

there

Speaker 2 2:56

we go.

Speaker 3 2:58

Can you hear me? This Should I project? I project a little Project. Project.

Speaker 5 3:20

Hey, that works

Speaker 3 3:20

too much Now.

Speaker 5 3:25

That's

Speaker 3 3:25

still a bit much. Is it that?

Speaker 5 3:33

I'll be really careful.

Speaker 2 3:34

It's going in now.

Speaker 5 3:36

welcome. It's great to hear. See all of you. so what I'm gonna do, actually first I wanna acknowledge right up fine. a number

Speaker 6 3:47

of people. So. From the of South Bend, Barbara, Dale, and Anna McVay, who is here.

Speaker 3 3:54

they've been sort of

Speaker 5 3:56

project

Speaker 6 3:57

managers. Should I

Speaker 5 3:59

put it

Speaker 6 3:59

down?

Speaker 7 4:04

Yeah. And if that doesn't work, put this on state level. There's two, one for the podium. I think that's good.

Speaker 5 4:16

So let warn you to, while we're, getting fit. so Barbara Dale is the project manager for the Office of Sustainability and she's really coordinating a lot of people on this effort. autumn, Nick Bay is also spearheading, coordinating some of the interns. And we're, Greg Thompson is the city forester. He is an absolute wonderful resource in terms of thinking through, uh, trees. And then John Martinez and Jacob Kosinski are fabulous. They've given me. Spoils from city parks, which turns out to be a more difficult question sometimes than you might think. And so I really appreciate their willingness to allow this project to go forward. then also from Ben, we've had people from the Department of Physics, so Brian Davis and Lag, who you'll see, how we, you've been partnering with them. Um, and, and Andy Schnabel in biology and Zachary Shrink in sociology and sustainability studies, have also contributed.

Speaker 3 5:11

Yes, good technology works. So

Speaker 6 5:22

let's

Speaker 3 5:23

get down. So

Climate Change and Urban Heat Islands

Health Benefits of Urban Trees

Challenges and Strategies for Urban Tree Planting

Introduction to Soil Samples

Microbial Activity in Urban Parks

Speaker 6 5:25

what I'd like to do is, this is the first time we've actually done any ecology talk in this series. So I want everybody in this room to put your ecology hat on for the next 30 minutes or so. And what we're gonna do is take a walk through the city of South Bend, and there's many ways you could look at a city, you could look at the architecture, you could look at the road infrastructure, the bridges, the pedestrian and bike pathways. Um, but I wanna think about this from an ecological point of view and hopefully maybe get you excited about our future and the direction that we're going. This is Sample Street. Um, looking towards the jail, this is, uh, Jefferson Street. This is east of downtown, and then Washington Street, which is west of downtown. And, um, this past year, uh, the City of South Bend received a grant, um, from the USD, uh, USDA Forest Service, to, basically to increase equitable access to trees, and to green spaces. And if you look at where we are right now, so the average tree canopy coverage in South Bend is about 26%, but it varies by neighborhoods from as low as 7%, um, to higher. in redline districts. So these are districts who, from the 1930s, uh, people were not allowed to get home mortgages and live there. So they tend to be, lower socioeconomic, people of color and they have chronically been underfunded in terms of green space, uh, underfunded in many ways. But anyway, this grant is solely focused actually, uh, on those, districts. So on average they have 17% canopy coverage. and the goal by 2050 is basically to double canopy coverage in the city. the initiative is gonna start over this next five years. So actually what I'm talking about today is a project that's, we've been in the works this summer, sort of getting things in place and thinking about things, but it's really not starting, uh, until this next year. so the first thing is to establish nurseries in the city to grow 9,000 trees, um, to kind of work out some of the kinks, get some of the workforce development and education and community engagement in place, and think about what are the problems that we're gonna, because, so here's the scale. we're looking at plant. In order to meet that goal, we have to plant a hundred thousand trees. So this is an extraordinary effort, and it's a historic investment in our city that will really change, uh, the landscape in many ways. So the South Bend City departments are working with community partners, on education, workforce development, community engagement, thinking about what is working as well as what needs to be adjusted. So, what I am gonna focus on tonight is thinking about why does urban tree canopy matter? Why is this historic, tree species diversity? Where have we been and what are the future goals? And then why does soil community diversity matter? And I hope to make you all really fascinated by soil. By the end, that's the real goal. So here's two aerial shots in South Bend. One is Rum Village Park, which is on the southwest side. This is the west side of downtown. You can see that they differ a lot, almost a hundred percent tree canopy coverage on the left to none. And, if we think about why does tree canopy matter? One of the things is climate change. So we know that, um, so this is data from Purdue University. If you go from 1895 up to 2017, the black line is showing the five year average. So going up and down, the dotted line is showing the trend, the linear trend. And what we know is that the amount of rain is increasing. We also know that we're having more drought. This is already happening. And if you look at kind of the average, compared to the early 19 hundreds, we're getting about five more inches, five to six more inches of rain. And that rain is unpredictable. It's coming in deluges. It's not spread out nice, so it can just soak into the ground. So trees can help trees. Reduce runoff. So you see 10% runoff there. And also trees allow more of that water to soak into the ground. This is helpful for water quality.'cause if you have less runoff, then you can get some of those pollutants going down into the ground, um, and not going directly into our river through runoff. If you compare this with an area that has 75 to a hundred percent impervious cover, in other words, concrete asphalt, notice that's 55% runoff, all of those pollutants going straight into the river, and notice how little infiltration there is into the ground. Trees can help with the water problem. We also have a temperature problem. Um, so this is looking at Indiana here. So of course this is where we are geographically and our location's not gonna change, but in the 2050s, so under a moderate emissions scenario, and actually under the, high emission, or sorry, moderate 2050 and 2080, these are temperature projections. So right now we have relatively cooler temperatures in the summer. So from the sixties up into the eighties, we have the occasional 90 degree day. so that's what it is now. But by the 2050s, notice that that's gonna shift to more commonly being in the eighties and higher under the high admission scenario. That puts us down in Texas. So hot and, there's a number. So increased heat can increase death. so this is looking at, um, the orange line is showing underlying cause of death from all deaths that were either directly or tangentially related, to heat. And then the blue line is showing just for the summer, so may to September. And one of the things that you see is that in the summertime in the US we have more deaths from heat related causes. and so it literally is impacting people, people's lives. It also contributes to the urban heat island effect. So what happens is that in downtown we have a lot of concrete and asphalt black surfaces that can absorb all that heat and that matters in terms of temperature. And this is course is where people are living. There's a higher density people downtown than there is in rural areas. So here this is an example in a downtown where it might be, you know, seven to eight degrees higher on a given day than it is in a rural area. and so this urban heat island effect exacerbates the effects of the having those hot days. And this is an urban heat island map for South Bend. The darker, the red, the hotter it is relative to the other places around it. So, I'd like you to notice Rum Village Park. If it's a hot day, that's where you wanna go. but look at this. The west side of South Bend is really, really red. And so we have, differences across the city in terms of how we experience heat on a given day based on what is surrounding us. This is the tree canopy coverage. So of course this is a rum village. And then these green dots here are showing where there's tree canopy. And so the goal of this project is to increase that tree canopy so that the places that really don't have much at all, have more tree canopy. And this also connects to other health issues. So for example, asthma risk. so in red this is showing, um, higher asthma risk in the 95 to a hundred percent, uh, percent tile compared to lower risk. and less than 50th percent tile. And again, this tracks that urban heat island map where it's hotter. We have increased asthma risk. There's several reasons, for this. One is that when you have hot days, you can get more air pollutants in the air. So one of the things that happens is that you get more volatile organic compounds that are forming and going into the air. In addition, you have particulate matter and all. And then IAP is indoor air pollutants, which I'm not gonna, talk so much about here, but all of these air pollutants contribute to chronic health diseases. So this includes stroke, of course, eye and skin irritation, respiratory diseases, so asthma, um, bronchitis and then cardiovascular diseases. So ability, of the heart to function in just makes it harder if you already have these underlying conditions. Um, it's going to be worse on days that have high air pollutants and also high heat. So. Amazingly enough trees can help reduce this in that, first of all, trees are helping to cool the area, so you get less of those volatile organic compounds and ozone forming in the first place. Second, the leaves trap that particulate matter. So all that particulate matter, tiny little particles in the air that when you breathe in makes it difficult to breathe and contributes to those asthma bronchitis problems. So leaves trap those little particles and then as those leaves fall down to the ground, they can decompose, go into the soil, and then the microorganisms can break, those down. So trees can reduce the amount of air pollution, in an area both through the cooling effect as well as literally trapping things in the air. this is a, a data set from Chicago showing that how many pounds of pollution removal per year for different, uh, air pollutants. So, for example, ozone is probably one of the greatest ones that's decreased, uh, followed by particulate matters. So this is particulate matter size, 10 microns. The nitrous oxide is here, and the sulfur dioxide and carbon monoxide. And as, so on the X axis we have diameter of trees. So the larger the tree, the more air pollutants, it has more leaves, cooling effect. so more trees really has a measurable effect on the amount of air pollutants. In addition, of course, to get at the root of climate change is reducing how much, uh, greenhouse gases are going into the atmosphere of which carbon dioxide is one. And through, photosynthesis, trees take up carbon. they then store it. So all of this wood here in this lovely sycamore tree is storing that carbon forever, the length of the life of the tree. And of course the larger the tree, the more carbon is stored. And then there's also an annual effect in that. the amount of carbon dioxide that's removed from the atmosphere daily as photosynthesis is occurring, also increases, as tree size increases. So this is carbon removed annually and pounds per year. The largest trees are re reducing or, taking out the most carbon. So, One of the things that we've been doing is partnering with the physics department at IU South Bend to actually measure CO2 on the ground and see if you have different landscapes. Can you actually measure differences in CO2? Like, can you in real time? So what the physics department did, so, uh, Brian Davis and Elon Levine, help build these CO2 sensors. So this is, there's a little computer in here, and then wires going out. This is the actual CO2 sensor here. Uh, when we actually use them, we protect them with really high tech PVC pipes, uh, to cut down on wind noise, rain, et cetera. Um, and so this is, physics students that are building those CO2 sensors and, Getting the sensors calibrated and so forth. what we did in theology class is we took'em out onto campus and say, okay, great. You built them in the lab. Do they actually work in the real world? and so this group here, so Tori, Darcy, and Carly, um, they, uh, tested the sensors, in two, uh, parking lot islands. This one has gravel and a tree, a ginkgo tree. This one has grass and a crab. Apple tree. This was done at towards the end of October, early November. So photosynthesis is already kind of ramping down. and so what they did is they put the sensors out in these, parking lots each day, same time, 60 minutes. and then compared the amount of CO2 levels in those two areas. And they wanted to get every day of the week because we can have different amounts of traffic going on campus Monday through Friday. So, one of the days when they put the sensors out in one of the parking lots, somebody was sitting in their car with the car running. So that showed that if you run your car, the CO2 is really high. but if we look at the other four days when there are no cars running and we're just looking at comparing those two parking lots, um, this is what the data looked like. So in the gravel, parking lot, the carbon dioxide is above 440 parts per million on average in the grass parking lot. We're not talking great vegetation here, grass a little bit less. Um, this was a significant difference. and it's not a lot. so it's on average about 30 parts per million, but it was consistent every day consistently a little bit lower. So if you're thinking about not just two parking lots, but an entire city, this could make a difference in terms of literally how much CO2. So in the South Bend Urban Tree Project, um, the benefits of doubling, um, the tree canopy, decreasing storm water runoff, reducing carbon dioxide levels, reducing the urban heat island effect, helping to cool buildings, which reduces energy usage, which reduces carbon output, and then also improving air quality by reducing particulate matter and ozone. So what tree species? We have a hundred thousand to plant. So this is, uh, not a trivial, question. This is showing. So looking down Washington Street and Miami Street, it's hard to id the photo. Uh, the trees in these photographs, they're all calorie pair. How many people are familiar with calorie pair? Everybody? Almost. Okay. So calorie pair, you might've heard it as, as Bradford pair. It was introduced as a horticultural tree, actually back in the 1930s, I think, to hybridize with pear. But then in the 1960s it was discovered it was a wonder child of the nursery industry horticulture. So it's everywhere. And not only is it everywhere here. Um, it's everywhere in Indiana. So this is looking at the street tree distribution across five, across several mid-size, um, cities. I'm gonna focus on South Bend, but it actually doesn't matter where you are in Indiana. You can identify the top five tree species. So in South Bend, our top five that, add up to more than 50% of the trees in our city are silver, maple, Norway, maple, sugar, maple, red maple, and calorie p. and in all of these cities, calorie P and Norway, maple, and then Siberian Elm, for example, are in the top five trees. So what was done in the 1970s and 1980s when trees were planted is that they were planting these horticultural varieties that can really withstand urban conditions, which are not trivial. and so of these five, two of these are invasive. So Norway maple is an invasive tree, not native to the us. Calorie repair is invasive, and not native to the us. These three sugar maple, red maple, and silver maple are native to Indiana. They're all maples. so again, we're not getting a lot in terms of diversity. so. If we think just a little bit more about calorie pair, the reason why it was planted is that initially people liked how it looked. So it has white flowers in the spring that you might be familiar with, and also the shape of the tree. it is kind of a little wonder kind of trees in that it can really tolerate restricted root space, compacted soils, it tolerates pollution, drought, it even tolerates salt. So it grows well in these tough conditions and you see it everywhere. The problem. Oh, one last thing. if you drive from here down to Indianapolis in the spring, you'll see all along the roadside, it's escaped. So one of the problems is that it just out competes. Um, so these were planted. None of these were planted, and it's just all throughout the state. So it's a bully. And then the Norway maple. So again, this was widely planted in the 1970s, 1980s because of Dutch Elm disease. So we used to have a lot of elm trees, but then Dutch Elm disease came in, kind of wiped out the, elm trees. And then the Norway maple was planted. So this is a large tree. people liked the color and the shape of the tree. It has a really dense foliage if you're under a Norway, maple, really high shape. so this aesthetic appeal and also this amazing ability to grow in difficult places. It can tolerate compacted soils, restricted root space, tolerates that air pollution drought and it tolerates salt. So, but in addition to that, it, it's actually changing our soils. So one of the things that nor this was a study that compared Norway, maple to red. Maple. Red maple is native. Norway is not. So this red maple, the roots, are, have different bacteria associated with them and there's more bacteria associated with them. And it alters the nitrogen cycle. The nitrogen cycle is run by bacteria and so in particular it increases the nitro flying bacteria. So you get more, a lot more nitrous, oxides in the soils, which other plants can't use as well. Most plants prefer ammonia, in this part of the nitrogen cycle. So it changes the soil microbial ecology, and it makes it more difficult for other plants to grow. it's just one of the ways in which it's kind of annoying. So one of the things that South Bend is actively doing is taking a very different approach this time. Um, one is that they're increasing the diversity of trees that are gonna be planted. So for example, I think, so they're still working out what trees will be planted and part of it has to do with what trees can actually be gotten and grown in the nursery and so forth. But, I think there were over 10 species of oaks, uh, that are all native to Indiana that are on the list. so the majority of the trees on the list are native, and that's really, and then also just the plain diversity is much greater. And so that will help buffer against diseases, more diseases and pests will be coming in. and that will help buffer against that. And then it also better supports biodiversity. So one of the things about native plants is that they support more organisms. And so this will help in that regard. In addition. By planting a greater diversity of trees, we're also buffering against climate change. So one of the things that has been, um, predicted, so looking at trees and what climate do they need to grow, some of them aren't going to do very well. So American Beach, black cherry flowering dogwood, Northern red oak, sassafras shag are ery. White oak, are all predicted to decrease by 2100 because the conditions in Indiana aren't gonna be as favorable for them as they are now. They'll still be here, but they're, instead of being a dominant tree in our area of forests, they might decrease. Um, at the same time we have, if we look at new, so these are trees that aren't really here very much now, um, but will are predicted to become more common as they move north. so blackjack, oak, lob, lolly, pine, pecan trees, these are things I associate with the south and certainly not Northern Indiana. These trees are native to here, expected to increase, and then, no change. and so we are gonna have a shifting of what tree species occur here. So getting a greater diversity of trees out there will help buffer against that. all right. It's really tough to be an urban tree. This these are the conditions that they're growing in. And you can't just say, oh, I wanna plant all these things. This is the reality. Look at this. There's sidewalk here, there's road on this side, and then there's this, and then there's a gas pipe there. So, you know, you have to have maintenance workers getting access to that. So the soil's gonna be dug up, this tree. Has a little rocks on around it. So again, this is gonna increase the stress for the roots. and then this tree has a little collar around it. Not that it's gonna run away, but it's very stressful. So these are stressful conditions and um, and we know that when we plant trees, we expect a certain amount of mortality. But, so this is looking down Mishawaka Avenue. and so. This is River Birch Swamp White Oak. Um, this is also swamp White Oak. These were two were right? All of these are native trees. these two were right next to each other. This one's doing great. This one not so great. We'll see if it comes back next year. And then the river birch, some were doing okay, some were not. The yellow wood, which is actually a tree from Southern Indiana, is actually doing pretty well along Mishaw Avenue. So, the conditions are tough and, and thinking about what do we need to do to increase the survival of the trees that we plant? And so this is really one of the things that, We are, thinking about. So in particular, Andy Schnabel and I are thinking a lot about, uh, mon. So in the tree nurseries over the next five years, we'll be monitoring tree health and other ecological and environmental benefits that those nursery have. the other part that I'm really interested in is focusing on soil quality. And so what I'm gonna do is show you some of the results of soil studies that we've piloted this summer to begin to understand why soil is so interesting and why it's so important in thinking about urban landscapes. So I'm gonna start on the campus of South Bend. to orient you, this is Ironwood Drive moving south. This is the pedestrian bridge here. Um, student housing is on this side, Lincoln Way, west is, uh, east is on here. And when they put in student housing, they built two retention ponds. there are pipes that go underground that drain water from Lincoln Way East and also the, parking lots here and drain them into both of these wetlands. The wetlands, then filter that water before it goes into the river. in, and so the other thing I should say, so when they built student housing, they dredged this area. They built up berms here. They put in fill soil. I have no idea where the fill soil is from. The other thing is that the history of this area for over 130 years was used for a golf course, a NASCAR race track, an amusement park. I don't know, a lot of things for over 130 years, but it was not native landscaping. So 130 years of intensive use, compacted soils. And then the top soil was dredged away and filled dirt was put in. So that's what we started with. Um, and then the retention pond. So this is how they looked when they were first planted. The grass was mowed right up to the edge. the biology department got several grants to add native plants. So we've been doing this since 2012. they look quite a bit different now. Succession is working. And one thing that I wanna say is that every plant has a different chemical profile. So when plants grow, of course there's the above ground part that we look at. But below ground, the roots are secreting chemicals into the soil. And I already told you that Norway maple, the chemicals that it's secreting into the soil attract bacteria and a certain kind of bacteria that manipulate the nitrogen cycle. But every plant is secreting root exudates into the soil. And this has effects on beneficial fungi, beneficial bacteria, also pathogenic bacteria and fungi. These are the ones that cause disease. So they're shaping the soil, affecting the pH and what grows there. So what we were interested in is. We know we started with similar soil in this area and that we've had about 10 years of native plants in one area, grass in the other. So Perla Diaz joined me this summer and we sampled soil all over the place. I'm just showing you a little bit of this, but on campus we sampled in the areas that had native plants and then about 20 feet out in the grass. And the question was, is there any difference in terms of what's living in the soil? It's only been 10 years. So the way that we do this is we collect soil, we put it in a bur funnel. so we put soil in here. You put a hot lamp on top, it dries out the soil and heats it up. So any critter that's in there crawls down to the bottom and then you catch it. And so that's how we can see, uh, the invertebrates. It's a way of capturing the invertebrates in the soil so we can control for the amount of soil that's put in here. And, see over time. So, um, here's comparing the native plant areas to the grass areas. In terms of the number of species that wasn't so different. It was pretty similar, six, five to six species. The abundance was very different. So we had 51 individuals captured in the same amount of soil in the native area compared to 27 in the grass area. And then the distribution of the species is different. So we had ants in the native area, but we had a lot more ants. In the grass area. and so, and the other thing that's different, notice we have these mites and then garden centipedes, and I'll talk a little bit more about both of those. so there were some difference. We also had a lot more beetle larvae. So if we take a look, um, so if you dig in the grass, uh, a lot more ants and then these beetle larvae are feeding on the roots of the grass. Um, we didn't find these actually very much at all in the native plant area. Um, but we found more garden centipedes. So these are herbivores, uh, that are feeding on dead decaying matter and they need moist areas. They cannot handle being out in a hot sun. and then we also found mites. These are super cool. These are a really diverse group, but they're, some of them are predators. So one of the things that we're finding is a more complex food web. In the native plant area compared to the grass area. So more layers, trophic layers, um, so higher abundance, more even distribution of species. And then we picked up some that weren't very common in the grass areas. Um, we also compared the ability of the soil to hold water. So if soil has good structure, um, you'll get these healthy soil aggregates, the roots can go deeper into the earth. and then you also have, um, healthier soil. It's not so compacted down here. In contrast, if you have a tough urban soil, you're gonna get this crust on top, smaller soil aggregates, tightly packed, blocky soil, and then really deep compaction. And it's hard for those roots to get very deep. so in this one, this. Soil can hold more water compared to this one. In addition, we looked at the amount of carbon in the soil, and the way that we did this is we collected soil. So this is the raw, well, it's actually dried, but it's a dried soil sample. So this is what the soil looks like initially. We then put it in a furnace. we heat that furnace up to a thousand degrees Fahrenheit, pretty hot, and that burns off all the organic matter. And then you compare the weight before and after, and that, so this is the mineral. This is how it looks like afterwards. So this is what the minerals in the soil look like, and this is what it looks like before when you have that carbon in the soil. Okay, so let's take a look In, the native plant area, there was significantly higher water holding capacity about, 5% higher compared to the grass. There was also, more carbon, although this difference wasn't significant, but trending in, uh, that direction. So more water holding capacity. A little bit more carbon if we look at the tree nursery site. So the city already has some tree nurseries, so we started looking at them and the way that they're planted. So you have a row of trees and then grass strip and then a row of trees. And that's so you can, they have to be able to get access to the tree to, to get out and then planted in a neighborhood. Um, so it's a way of, of dealing with the trees. So that's, what the tree and these tree nursery sites have only been in place for about five plus years. So, and they were put in vacant lots where a house was there. Initially it was torn down, really compacted soils. and then these tree nurseries were put in. So we compared, um, for these two areas. and so even in an area that hasn't been there for very long and we sampled under the tree versus in the grass, you still see differences in what's in the soil. So more millipedes, more of those gardens. Centipedes, isop pods. There were some ants and also true bugs in the grass areas. A lot more ants. We did pick up mites, but fewer milli peds, fewer gardens than de pedes and so forth. So there's a difference. The diversity itself wasn't that great, but there was a difference in the kinds of things we were finding in the distribution. and then also in the tree nursery sites, there was, um, significantly more carbon in the soil under the trees than there was in the grass. and that is not surprising, but still getting more carbon into the soil. It's a way of sequestering that carbon. It's a storage place. So one of the reasons why vegetation matters is because if we're thinking about non-natives and their root structure, so this is SCU turf, so most of our grasses look like this. And then most of the native plants that we have have much deeper root systems. So part of the difference in the structure of the soils that we're seeing, just the roots are going deeper. They're supporting, they're secreting different root exudates. And so that is supporting different soil communities, um, increasing carbon in the ground, and also increasing how much water can infiltrate and go into the ground. we were also interested in the microbial, composition. and so we compared two parks. So Pin hook Park, um, we sampled two sites here and then Howard Park, and I don't know if you can see it from the audio. All of these green things here are trees. and then so pin hook has a lot more trees. And then, um, Howard Park, we were sampling from these dune and swale sites where they've been planting native plants. but generally there's fewer trees in Howard Park, compared to pin hook park. and one of the ways that we can look at microbial activity in the soil is to do something called a teabag. Uh. Index. So, this is Roose tea. So this is a South African tea. It's a very woody tea. and wood is primarily decomposed by fungi. Green tea is primarily leaf material, and that's primarily broken, broken down by bacteria. So when you put them in the soil, you bury them in the soil. Uh, we keep them in tubs at the campus gardens, and I, I, I'm sorry to say that the groundhogs have some interest in teabag. but anyway, unintentional experiment. so we track the amount of decomposition over six weeks. So if you're getting more decomposition in the roose teabags, that means you have more fungal activity in the soil. If it's more in the green tea bags, then more bacterial activity in the soil. Um. So this is how it looks for the two parks. And what I want you to notice is that Pinhook Park that has more trees has almost twice as much decomposition, um, due to fungal activity compared to Howard Park, which is much more grass dominated. and then the green tea was actually pretty similar. So in general, you get the green tea will decompose much faster than the Roose tea, so over 50% decomposition over that six week period. so there's plenty of bacterial activity in, in both of the areas. and to some extent you expect this because in forests they tend to be fungal dominated, in the soils, whereas grasslands tend to be a little bit more bacterial dominated. But you can even see this in urban areas, which I think is cool. and one of the reasons, um. This is important is that so fungi grow, they have Mycelia underground, they have these thread like structures called hyphy. And so this is hyphy that's going in the soil. And these hyphy, as they grow, they kind of bind those soil aggregates and allow that soil to form larger aggregates than if you don't have those fungal hyphy. And so this is soil here that's just rich. You can see all that white that's fungal, uh, mycelial mass, and that's helping bind the soil together. This was a really cool experiment that was done, um, by the Soil and Water Conservation District in Jasper County, which is just a little to the south and west of us. they compared two farming practices, so both of the fields had similar soil type and um, both had a corn soybean rotation for over 20 years. Look at this soil. This is beautiful. It's holding together. This soil is falling apart. This is the soil that on a windy day is just gonna, all that top soil's gonna blow away. And what was different between those two fields is that one was tilled and the other wasn't. So when you're regularly digging and tilling and disturbing, you're breaking up all those fungal hyphy. And, and then in addition, there was no, so this is, uh, nitrogen fertilizer here. So there was no fertilizer applied here. When you apply fertilizer, that affects the microbes in the soil. Um, and so if you don't apply fertilizer, it allows, and if you're not tilling, it allows that microbial biomass to build up. And so over the course of 20 years, you can see the difference. In addition, they were also using a cover crop, so they weren't allowing the soil to be exposed to the air at any point. So anyway, a really nice visual demonstration of how those microbes can hold that soil together if you let it. So what I want you to think about is, um, we really need to think from the ground up and that native plant species can, um, increase soil biodiversity, water holding capacity, carbon content. In other words, organic matter in the soil. Changes in those soil communities can happen fast. I wasn't sure. I thought, well, maybe we'll see nothing. but that's not in. Over the course of five to 10 years, we're seeing differences, less disturbance, improve soil structure. This is not practical in an urban setting, but still may useful to know. and then non-native plants can disrupt that soil microbiome. The last thing that I wanna do is connect soil biodiversity to human health. There was a really lovely review study that was published in 2023 that looked at a global, pulled together data from all over the globe, every continent, and put together what are some of the patterns that we're seeing. So on the left we have lots of different critters in the soil, high soil diversity. these colored circles represent different kinds of microbes that are in the soil. So for example, methanotroph bacteria. Those are the blue squares. There's relatively few on this side. There's a lot more on this side that has lower invertebrate soil, uh, diversity here. and these methanotroph bacteria release, methane. So that's one of the greenhouse gases. So if you have low soil micro, Invertebrate diversity, you can get more of these methanotroph bacteria that are taking over and that can increase methane emissions. in addition, if you look at the pathogens, when you have more, A greater diversity of critters in the soil. You have a greater diversity of microbes in the soil and that helps keep down some of the pathogenic, the bad bacteria and fungi, um, compared to here. And this affects our health. So for example, on this side, people in urban areas tend to have more allergies, infections, asthma, compared to this side. So a better immune system and a healthier human microbiome. And there was a really interesting study of daycare centers in Finland. They compared, um, 10 different daycare centers in two different cities in Finland. and they compare. And these were young kids, three to five years old. So this is when their immune system, um, is developing. they had three different kinds of play yards. So there was a standard yard that had manmade materials. and then they had an intervention yard that started off as a standard yard, but then, um, was converted to, um, a yard that they literally added leaf litter from the forest. They added sod from the forest. They added these peat blocks that the kids could play on. they also had annual, uh, planters that the kids could play around in. and then there was a nature oriented yard. This was kind of the control side, so this was play yards at daycare centers that already had some of these natural features. and so at the beginning of this study, they measured the skin and gut microbiota and then also the immune system and then see how did it change over the course of 30 days in the intervention yard. Yep. One month. so they looked at the immune response before, and at the end of a month, 28 days, the kids spent the same amount of time playing outside, so about one and a half hours every day. And, uh, they all had uniform meals at all of these daycare centers. Of course, their home environment could be very, very different. So that was not controlled. and what they found, so in these standard yards where you have mostly manmade, uh, materials, um, compared to these yards, one of the thing that they found is that if you compare the standard yard to the, transition yard, um, the soil itself had a lot more diversity, higher diversity of this gamma proteobacteria. This is a commensal bacteria, so this is one that's good if you have a lot of it. It helps keep the pathogens down. So there was more of that in the soil. And then when they sampled the skin. They had, the kids had a greater diversity of that skin, bacteria at the end of the month compared to the beginning. And they also saw improvement in the immune system in several ways. So one is that there was an increase in cytokines that decrease inflammation. There was a decrease in cytokines that increase inflammation. There was an increase in T cells that help regulate the immune system. How do you know yourself cells versus what's invading? And this is the core of allergies that you attack, things your immune system gets all busy attacking things that it shouldn't. So this is really important in terms of managing allergies. and so, The exact link of how this work is still being worked out. But basically, if you have really high microbial diversity on your skin, so this is looking at, so the epidermis, so we're looking at the skin and then going down below into the dermal layer, on your skin. All these different colors are representing different kinds of bacteria, um, microbes that are on the surface. and if you have higher microbial diversity, then you have lower of those pro-inflammatory cytokines. If you have low microbial diversity at the skin, these, bacteria can secrete toxins, which then triggers the immune system and you get a lot more of these inflammatory cytokines. So you get red itchy skin, you get allergy, outbreaks. so they were looking at both atopic dermatitis, so itchy skin as well as food allergies. So in a very real way, increasing soil biodiversity, not only could be important for improving the health and survival of trees, but it's important for us. So healthy soil support, more water storage and filtration, more carbon capture and storage, better biological function and diversity, and then also production. So the ability of plants to grow. So what I want to leave you with is that. Our urbans landscapes really matter. They matter to every single one of us, in really fundamental ways in terms of biodiversity, the species that can live our ecosystem function, clean water, clean air, human health, storm water management, and of course dealing with climate change. And so I want to leave you with, we all need a little mini forest in our neighborhoods. And this is Rum Village. It's one of the best forests in the city of South Bend and one of the most extensive forests. And the amount of services that it's providing to the city is extraordinary. So supporting our city parks, allowing them to get increased canopy coverage on our school yards, allowing them to increase canopy coverage and then in our neighborhoods, which have been underserved in particular, increasing canopy coverage there is really important. If you are interested and wanna stay informed on this project,'cause again, we're just kind of getting going. you can go to the climate action. This is the South Bend City Climate Action Planning. and you can sign in for updates. And with that I'll take questions. Yes. Thank thanks.

Challenges and Solutions for Urban Tree Planting

Speaker 8 48:20

Thank you very much. Is a whole set of explanation ways of. Uh, opposition that they must prefer native trees. I did not know that native trees are going to help the soil.

Speaker 6 48:38

so let me, let me add one caveat to that. we do want native trees and the city is focusing on native trees. however. Urban settings. This is not a forest. So I've studied old growth forest. This is nowhere near that kind of setting. And many of the cultivars that have been developed have different branch structures so that when you have storms, they don't break, they, they're architecturally more sound. which is important. We don't want branches falling on houses. we also have, uh, some of the trees have been bred to be more salt tolerant, dealing with those compacted soils, and so forth. So, uh, we probably do need, if a dead tree isn't gonna help us. And I think I showed you those photos. They were all native, but a lot of them were not doing great. So the question is, do we need, is this a matter of watering the trees? Oh gosh. I guess it was ma. or is it something Yeah, it was here. These are all native trees, but if they don't survive, then that's not gonna meet the storm water management, the air pollution, the carbon. so I think one of the things that we are really interested in with the nurseries is tracking what trees are doing well in these urban settings. And I, I think there probably needs to be a compromise. So the majority are native, but there might be, situations where having a live tree will be preferable to a dead tree.

Speaker 8 50:11

Oh, right.

Speaker 6 50:12

Yes.

Speaker 8 50:13

are you doing any research on Cold wars, natives, cold bars because you have to, whether they are having an adverse or Yes.

Speaker 6 50:22

I am not. But, uh, Theresa Culley in, uh, at Ohio State University has been working on that for the last 20 years. She has a lot of data on testing tree cult of ours, and thinking about their ecological impact. And it's mixed. So just like the perennials, cult of ours. So for example, echinacea has is a common cone flower, and it has a lot of cultivars. Some of them attract pollinators just as well as the straight species, and some are terrible. so you really have to look at it species by species, which is really time intensive. And when you're talking about trees in the lifespan, that data's harder to come by. But there are people working on it. So Theresa Culley at Ohio State University is one of those people. Yes.

Speaker 9 51:09

When they were planting those, the trees, my first concern was I don't think they're gonna survive because an extra roadway, the salty roadways, it allows a slow in confidence. So I always would worry thinking about what is solidity of that area from what is the impact of salt on each trees vector roadway.

Speaker 6 51:27

Most plants don't survive salt. If you wanna kill a plant, give it salt. Um, now I mentioned that Norway Maple and the Bradford Pear, they can tolerate salt. So, uh, rag Mighty is another one that actually does super well in salt. So the, uh, and that's an invasive species. Some of the native species can tolerate salt better than others. And so that's one of the things that we have to pay attention to in the nursery. Um, and see what is growing well. Um, and the city's also been talking about maybe we need an ambassador program. So for the first couple.'cause when you plant a new tree, it's, it's stressful no matter what. And so maybe we need to have kind of an ambassador program. You take the street and take care of watering it for the first two years. So that's one idea that's been floated. yeah.

Speaker 10 52:15

I was wondering about planting from ski in place and what's the possibility of trying that?

Speaker 6 52:23

It's a great way to do it in, in your own yard. and trees actually have been shown to have better, so the transplanting process is stressful. So if you just grow up from the seed, um, generally you have to grow multiple seeds so the animals will eat the seeds, uh, and when they're young you have to protect them and they're really, really little and they will grow over time. but in terms of this case where we're trying, so we're planting in urban areas, schoolyards, we need to see probably faster effects, um, and get more trees established more quickly. So going from seed, people might be able to do it in their own yard and that's a great way to do it. But, at the city scale, I'm not sure it's viable.

Speaker 11 53:10

I wanna speak about those trees that you pointed to on Mishawaka Avenue. I've been, I've been watching them. Yes. Yes. And, um. You know, they, they haven't even experienced winter. I don't think they're, how long have they been in there? I don't know. Months, I think. And, and they really needed more water. I was thinking they need to, um, really up the number of times that young trees are watered. And I love the idea of the ambassador. I mean, I brought a tea pot out there one day because my awesome fellow like, oh, I kept dead watching this last on office. But of course it made no difference.

Speaker 6 53:50

Yeah, well some of them are doing great like this oak and these two are right next to each other. So it makes me wonder what happened. Was it a transplanting thing? This one got treated nicely and this one, maybe the roots were damaged. Is the soil different? They're literally right next. So this is the swamp oak that's not looking great. And then the one behind it that's looking really good. So, um, it's something that we're paying attention to. yeah.

Speaker 5 54:17

The issues of compacted soil, in particular in urban environments. I'm wondering, given that native perennial plants have those wonderful root structures as well that help deal with compaction, what, like, has it been looked at planting some native, perennials along with some of the trees and some of these environments? Does that

Speaker 6 54:37

Yeah, it, is there a benefit? It's been floated. That idea has been floated. I think part of it is the scale of the planting, but um, has been one suggestion is like maybe in some of the school yards where there's interest in doing that. Increasing the native plantings under the trees in some of the city nurseries. Maybe in one section could we do a little pilot thing and see if we plant native plants, does that actually improve the survival in terms of plant transplanting it back out into the urban side that's gonna increase maintenance and Unfortunately we're not increasing the number of people in the city office. Like if you wanna talk about people stretched really, really thin. Yeah.

Speaker 12 55:20

My memory of the IU South Bend campus is that there was a beautiful tree camp in canopy on the quad that has been succumbing to a parasite'cause it's one species have to it over and over and over again.

Speaker 6 55:35

The ash tree.

Speaker 12 55:36

Yeah. And so on a, on a location like these, how many different species would you need in order to decrease the odds of the jumping from tree to tree of some future parasite?

Speaker 6 55:48

That's a really good question. I think Brent Thompson, who's the city forester, I know he's been thinking about like at the neighborhood level, what's the diversity of trees that are both the right tree for the right place, for the soils, for the width of,'cause The tree width here varies quite a bit. So what's appropriate for each neighborhood, but also then what's the diversity of trees? So I, I know they're looking at that. I don't know the answer. Yes.

Speaker 4 56:20

I dunno, you probably have considered this, this, uh, tree inventory, especially in urban areas. If, if a tree gives fruit, people feel. Maybe even take care of it.

Speaker 3 56:35

Mm-hmm.

Speaker 4 56:35

has there been any thought that maybe more food trees so that people feel that they get something, you know, outta it and then they would take care?

Speaker 6 56:46

Yeah. Um, I think persimmon was on the list.

Speaker 5 56:53

There are some fruit trees on the list. but fruit is good for some people and bad for others because when it drops on the sidewalk, it creates rotten gross fruit. They, you have to step around, you have to clean up. So whi cared for, and when you get to eat it, it's excellent. And when it's on the sidewalk where no one is really clearly taking care of it, it's a little bit of a nuisance. So there are fruit trees on the list. They don't tend to make it into like these tree lawn spaces, but we've considered, you know, could they be kept at. Parks were in people's lawns or promoted in areas where there, there are truly people there who would care for them.

Speaker 13 57:34

Is the focus on deciduous trees that for the most part,

Speaker 6 57:38

yes. There's a few. So white pine is on the list. There's a cypress bald Cyprus, ginkgo is on the list. And that's, a gno sperm. I think that might be it, though. I don't think there's ginkgo's, not native, but it wouldn't be invasive either. They're just planting males so.

Speaker 5 58:01

Question about the male versus female piece of that. Like, does that matter when you're selecting the tree subhan, was that gonna potentially affect like quality of life or people nearby for human allergens or anything

Speaker 11 58:12

ginkgo?

Speaker 6 58:13

No. Uh, so in the case of ginkgo, it's, it's DiUS. So there's males and females, other trees are hermaphroditic, so they can produce both. So most oak trees, for example, produce both male and female flowers so they can still produce acorns. and so in that case, the reason why the male ginkgos are preferred, uh, if you wanna come to the IUSB campus and stand outside the library in the fall, we have female ginkgo trees. It's one of the few places in the, in the city that you can see them. They have really cool fruit. ginkgo's are really interesting evolutionarily, but people mostly hate the fruit because it smells. And so the males are preferred because they don't produce the fruit and, and so you don't get the mess on the sidewalk. And also the smell.

Speaker 5 59:01

Is part of the plan to have the trees planted in people's yards, are, or as if all the, are all the trees gonna be planted on city property? And

Speaker 6 59:11

I'll let Ana take that one.

Speaker 5 59:13

Yeah, it should be a mix. So the city has access to the tree lawn, which is that area between the sidewalk industry. So legally the city can plant in those areas, but as private citizens, you know that you're the ones that maintain them. Yeah. So that area is kind of a crossover space. It's not quite public and it's not quite private. especially in lower income areas where people aren't gonna have the opportunity to be giving lots of care to those trees. Those trees will probably be planted more in the public right of way so that city maintenance workers can try to take better care of them. And we know that there's, been a lack of watering and care already. Right? The city, the city staff is, is pretty sparse, but we also want residents to be planting in their yards yard. If you have space for a tree, you should be planting there, right? If you have a big hot yard, we wanna be providing trees. So the city does tree giveaways. You can get three trees and plant them anywhere.

Speaker 6 1:00:10

I think those usually happen in the spring, right?

Speaker 5 1:00:12

To happen in the spring for Arbor day. But we're gonna start increasing those as we get more production. So there'll be opportunities for every kind of planting parks, private lawns, businesses, street scapes, sidewalks, you name it.

Speaker 10 1:00:32

Yes. Just following up on the mail, female question. I don't know if maybe you were. I've heard that some decades ago a lot of certain kinds of trees were planted in urban areas and it contributed to asthma and allergies because was a lot of problem. Do you remember? I don't remember which type of tree it was, but it was cedar.

Speaker 5 1:00:52

Sometimes the cedar do that.

Speaker 6 1:00:55

cedar might be wind pollinated, so I'm thinking it would be wind pollinated in order to contribute.'cause if it's insect pollinated, it wouldn't be a problem. I'm not sure about that. I do know that planting different cultivars actually contributed to the invasiveness of the Bradford pear. So there's like 30 different cultivars. So the Bradford pear was initially sterile, but then your neighbor plants a different cultivar and another neighbor over there plants another cultivar, and then they cross hybridized. And now every Bradford pear has fruit. So, there was that, but that wouldn't contribute to the allergy problem. So I'm not sure. I have

Speaker 7 1:01:33

look

Speaker 14 1:01:33

on, on your list of, of, of trees to be, uh, planted in the future. Is the American el, is that the true American elm? The one that has died?

Speaker 6 1:01:44

It's, it's, hybrid. So it has the genes that are resistant to the elm disease in that tree. So it's more resistant to the elm disease.

Speaker 14 1:01:55

So is a cult?

Speaker 6 1:01:57

Yes. But it's genetically the American elm, but it has the genes for disease resistance. And so this is why with the cultivars, I, I think we have to be, you have to look at each cultivar. Is this gonna be helpful or harmful? In that case, if you just plant an American elm, it's gonna die. And if we plant an ash tree, it, it's gonna get the emerald out ash bore. so, but if you have a cultivar that can resist that, it could be a perfectly fine. It would support native insects because it's mostly a native,

Speaker 14 1:02:35

but, but research has not yet established that conclusive. I take,

Upcoming Talks and Events

Speaker 6 1:02:40

I am not aware. I would have to look up, I, I know that the studies have been done to show that it's more disease resistant and it grows well in urban areas. I'm not sure about the insects. We need more entomologists. Alright, so let me just, uh, give a little preview. So this fall, we have more talks coming up. They're gonna be on the first Wednesday of each month. this first one is actually a, a Nobel laureate who's gonna be speaking at Notre Dame on Monday, September 9th. So if you're interested, you can join for that. and I think you can go to the Notre Dame website, get information. September 17th. So this is gonna be thinking about the global fresh, uh. Then our next, our Universe revealed lecture series will be the first week in October. It's gonna be on a Wednesday. It's gonna think, be thinking about chemistry and art. So it should be a lot of fun. in November, we will have a Nobel Prize panel discussion In October, the Nobel Prizes will be announced. Uh, then we'll put together people from the area who have expertise in that area. And you can come learn about the Nobel Prizes. It's always a lot of fun and, and it helps you understand, um, one of the top science prizes. And then in December, uh, we'll be thinking about astrophysics. so studying, old stars to understand new stars and, so another whole universe. So anyway, with that, thank you so much for coming. if you need a little bit of forest soil in your life right now, just to feel on the site. So this bin right here. Has four soil from Rum Village and this has soil from an urban grass area. And you can even just look at them if you don't wanna touch them, but you can just feel the difference. I also did some of the burise funnel, but it's a little bit hard to see. There's milli peas in simla and pot worms, et cetera in there, but it's gonna be hard to see. So anyway, but if you just wanna feel, you can feel the difference. So anyway, with that, thanks so.