Doug Tallamy is the T. A. Baker Professor of Agriculture in the Department of Entomology and Wildlife Ecology at the University of Delaware, where he has authored 111 research publications and has taught insect related courses for 41 years. Chief among his research goals is to better understand the many ways insects interact with plants and how such interactions determine the diversity of animal communities. His books include Bringing Nature Home, The Living Landscape, co-authored with Rick Darke, Nature's Best Hope, a New York Times Best Seller, The Nature of Oaks, winner of the American Horticultural Society’s 2022 book award. In 2021 he cofounded Homegrown National Park with Michelle Alfandari. His awards include recognition from The Garden Writer’s Association, Audubon, The National Wildlife Federation, Allegheny College, Ecoforesters, The Garden Club of America and The American Horticultural Association.
Episode Description
As we prepare to mark Earth Day 2023, many of us are also coming to terms with the latest climate report from the IPCC which said the world is on the brink of catastrophic warming. News like that can make it hard for individuals to know what they can do to have an impact on the environment. One movement suggests we can all help with conservation efforts by planting locally that’s the focus of this episode of Stats and Stories with guest Doug Tallamy.
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Rosemary Pennington
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As we prepare to mark Earth Day 2023, many of us are also coming to terms with the latest climate report from the IPCC, which said the world is on the brink of catastrophic warming. News like that can make it hard for individuals to know what they can do to have an impact on the environment. One movement suggests we can all help with conservation efforts by planting locally. That's the focus of this episode of Stats and Stories, where we explore the statistics behind the stories and the stories behind the statistics. I'm Rosemary Pennington. Stats and Stories is a production of Miami University's Department of Statistics and Media, Journalism and Film, as well as the American Statistical Association. Joining me is regular panelist, John Bailer, emeritus professor of statistics at Miami University. Our guest today is Doug Tallamy. Tallamy is the TA Baker professor of agriculture in the department of Entomology and Wildlife Ecology at the University of Delaware, where he has authored 111 research publications, and has taught insect related courses for 41 years. His books include “Bringing Nature Home: The Living Landscape”, co-authored with Rick Dark, New York Times bestseller “Nature's Best Hope, and the Nature of Oaks winner of the American Horticultural Society's 22 Book Award. And in 2021, he co-founded Homegrown National Park with Michelle often dairy. Doug, thank you so much for joining us today.
Doug Tallamy
Well, thanks for the opportunity, I really appreciate it.
Rosemary Pennington
What is the Homegrown National Park?
Doug Tallamy
Well, it's officially a small nonprofit designed to encourage people to conserve on private property. And we conceived it well, we are in the middle of the sixth great extinction event. And we've got parks, and we've got preserves, but they're obviously not doing the job. So we have to start practicing conservation on private property. And most of the country's privately owned 85.6% of the country east of the Mississippi is privately owned, and 78% of the whole country. If we don't do conservation on private property, we're going to fail. And we can’t afford to fail. You mentioned the serious problem of climate change, we've got a serious problem, biodiversity loss as well. And if you join Homegrown National Park, you can address both of those at the same time. It's simply an effort to use a little bit of social media, a little bit of competitiveness, the competitiveness of human nature, to get people to redesign their home landscapes. We've got 135 million acres of residential landscape. And if everybody put in some powerful native plants that support the biodiversity around us, we'd be in much better shape. So the question is, how do we get that message out to people and that's what Homegrown National Park is all about?
John Bailer
You know, this was, I'm sure you didn't just roll out of bed and say, you know, I think we should have Homegrown National Parks, that there was probably a little bit of you might have slept on it maybe a whole week before you came with this great idea. So can you talk a little bit about the origin story?
Doug Tallamy
Yeah, it's funny. You say roll out of bed, because that's almost what happened. It was early. I had gotten up early. I always get up early. But it was a Sunday morning. I had run across this statistic. This was 2005-2007. I think the statistic was that we had 40 million acres of lawn in this country. And I remember sitting at my kitchen table on Sunday morning, I said, well, gee, how big is that? And I started adding up the area of all the major national parks. And you can add them all up. And it's still less than 20 million acres. And I said, well, gee, if we cut the area of lawn in half, and you know, restore it to ecosystem function, because lawn doesn't do what we need it to do, we would have an area bigger than all of our national parks or major national parks combined. So I said, gee, we'll do this at home, we can call it Homegrown National Park. That's how the idea came about the fact that we needed conservation. That was a much longer story. And we can go into that if you want. But yeah.
Rosemary Pennington
I'd love to hear about how can people sort of engage in conservation in their yards? Because I think we imagined it as this very giant, monstrous thing that has to be done by an institution. How can an individual do this?
John Bailer
Yeah, you know, can I, just to add on that real quick, you know what she's asking, I found myself thinking, how do individuals tie in to your idea of ecosystem function?
Doug Tallamy
Right? Well, the first thing I tell people is that don't worry about the entire planet's problems because you'll just get depressed, and you feel like you're not going to make a difference. Focus on the piece of of the earth that you can make a difference on. And if you own property, it's obvious that's that's where you would start. So there are a number of things you can do. You can reduce the area of lawn because there are four things every landscape has to do if we're going to reach a sustainable relationship with the ecosystems that sustain us. One is protect the watershed. Another is sustain complex communities of pollinators. The third is the food web. In other words, choose plants that are going to pass on their energy instead of just holding it. And the fourth is sequester carbon lawn does none of those things. So reducing the area of lawn is a great step, step forward. We can use Keystone plants, the plants that are supporting most of the food web. We can, we can turn out our lights, our lights we have on at night, or replace the bulbs and put in a yellow bulb. Because light pollution at night is one of the major causes of insect declines that people are measuring. We can stop using pesticides that, you know, except for termite control, they're all unnecessary at home, we can fire mosquito Joe, who's killing everything without controlling mosquitoes. We can put in a pollinator garden, we can make into all kinds of things one person can turn around the ecological effectiveness of their little piece of the earth, they can see the results, which is motivating them to do more of it. They can provide a great example for their neighbors saying, you know this, I've done this, and I've done it in an attractive way that fits into our culture. So there's a lot of things that each person can do. And of course, if everybody did that, we wouldn't have these big problems.
Rosemary Pennington
You mentioned Keystone plants, what kind of plants are we talking about?
Doug Tallamy
Okay, we're talking about the plants that provide the most caterpillars. Caterpillars are the bread and butter of food webs, they are passing on more energy from plants to other animals than any other type of plant eater. Remember, plants are capturing energy from the sun, through photosynthesis. They're turning it into food, into simple sugars and carbohydrates. That essentially is all the food for animal life on the planet. Most vertebrates do not eat plants directly. Most vertebrates, invertebrates that ate plants. And those are typically insects. And again, caterpillars are the most effective in terms of moving energy from plants to higher trophic levels. And if you don't do that, you don't have the higher trophic levels. And that's called ecosystem collapse. So which plants are best at doing that they're the ones that support the most caterpillars, and we know what they are, because there's 100 years of caterpillar hosts records and literature. And it turns out that just 14% of our native plants are supporting 90% of the caterpillars that are out there. So we call those 14% The Keystone plants, the ones that are doing the best in terms of passing on that energy. And in most 84% of the counties in which they occur, oaks are the number one Keystone plant, so I could put my finger on the map almost anywhere and say you should plant an oak and be correct.
John Bailer
You know, it's an interesting question to me when you're talking about this reclaiming part of a yard or a lawn, it seems like it always touches on this, this need to change, a perception of aesthetics of space, and outdoor space. I mean, you know, one thing that comes clear and your book that this, that nature's best hope is, is that, you know, we have these invasive species that have been embraced these ornamentals, these alien plants that are alien to our community, to our ecosystem that we've celebrated as as this aesthetic ideal. And changing the idea of saying, you know, isn't it cool to see that, you know, my dead flowers are still being eaten by birds in the winter. That's a different mindset than saying clear it all out now, before winter comes.
Doug Tallamy
We've had this idea forever that plants are decorations. They've got the horticultural industry, which is not populated with ecologists they’re about decorating the landscape. And I understand that because plants are beautiful, and they do make beautiful landscapes. But we have not been choosing our plants based on ecosystem function. My message is we can do both. We can have ecosystem function and beautiful landscapes at the same time. So for 100 years, we've imported plants from other continents labeled pest free, meaning nothing can eat them, meaning none of that energy is passed on, so you've created dead landscapes. In the meantime, many of those plants that have escaped cultivation become serious invasives pushing out the native plant communities that do pass on their energy that do support the food web and replace them with plants that don't. So, you know, it's a very serious problem. But it's another, that's one thing I forgot that homeowners can do, they can remove the invasive plants that are already on their property, and most people do have invasives without even thinking about it.
Rosemary Pennington
We talked about this idea of plants being ornamental. And you know, I know my mother loves petunias and zinnias. But you talk a lot about the importance of planting indigenous plants to feed pollinators. Right, bees love petunias, ingenious too, but they may not do the same work as something that is native to the land. Can you talk a bit about that?
Doug Tallamy
Well, first of all, people think that all the only important insects are pollinators, they are very important. But don't forget those caterpillars, which of course, turned into moths, and many of those are pollinators. But you gotta support the food web and you've got to pollinate the plants. So those are two major things that insects are doing well. So it turns out that particularly if you're talking about about caterpillars, or insects that that eat plants that get their energy from plants, you have to remember that plants don't want to be eaten. So they protect their tissues with nasty tasting compounds, secondary metabolic compounds that make the tissues either bitter or toxic. While our plants do eat, or insects do eat, plants, and they do that by developing adaptations that circumvent those defenses they get around them. But that happens through a long period of co-evolutionary interactions. The insect is associated with the plant lineage for eons and develops the adaptations that allow them to get around those compounds so that they can effectively eat it. But when those adaptations are in place, now they're locked into eating that particular plant lineage. I always use the monarch butterfly as a great example. It is just an example because 90% of the insects out there are houseplants specialists just like the monarch. But monarchs, of course, eat milkweeds, and milkweeds are toxic plants. They're filled with cardiac glycosides. They're filled with milky latex sap that gums up the mouthparts of insects, monarchs have the adaptations to get around, they have physiological adaptations that store and excrete the cardiac glycosides and detoxify it. They have behavioral adaptations that nullify the latex sap. They snipped through the vein of belief before they eat it, and it cuts off the flow of the sap. So they're very good at eating milkweeds. They can't eat anything else. So if you take the milkweeds out of your yard and replace them with hostas, you've got a nice decoration. But the monarch then has two choices: fly away and find milkweed someplace else, or starve to death. And when you do that for 90% of the insects that are out there, and when there is no someplace else, and as we keep expanding our human footprint that is more and more of the case, then you get global insect decline, which is what we're looking at right now.
John Bailer
So you've done some studies where you've compared what an invasive species can support and the natives that have been there can support. So can you just do a kind of a quick summary of one of those types of studies where, where you've examined kind of a native plant plot, and, you know, kind of this invasive plot and the differences in terms of insect supported?
Doug Tallamy
Sure. We've done this studies for 15 years now, but a fairly recent one was very simple, went into hedgerows, agricultural hedgerows in Maryland, Delaware and Pennsylvania, with an undergraduate, and we measured caterpillar communities in a standardized way in hedgerows that were invaded versus hedgerows that were not, and remember, the invasive plants are basically from Asia. They're almost all from Asia here. So our insects have not been able to adapt to them. Well, we're going to measure that. So we looked at the caterpillar communities and invaded in an intubated hedgerows and found the bottom line was a 96% reduction in caterpillar biomass, the actual energy in that food web invaded hedgerows. And if you think of that as bird food, and it is, you've just reduced bird food by 96%. No wonder we've lost 3 billion breeding birds and this country when they did their breeding. 96% of our birds are rearing their young insects.
Rosemary Pennington
You're listening to Stats and Stories, and today we're talking about Homegrown National Park and the idea of individual conservation in our backyards with Doug Tallamy. Doug, you mentioned watersheds in an earlier response. How can John help improve the watershed? By what he plants in his yard?
Doug Tallamy
John can increase the amount of plants in his yard, and he can use plants that have decent root systems. Trees, of course, are the best, depending on where you live. You don't want to put trees in the high plains prairie of Colorado, and a lot of people tried to do that. But in most areas of the country, trees are appropriate. They have big root systems; they are keeping the water on site. So the reason I talk about watershed management is because lawn, which we have so much of now, about 44 million acres, is terrible at watershed management. The roots are very short. That gets sunbaked in the summertime; you get that downpour and you know, most of the water runs off, taking with it the herbicides and insecticides that you put on your lawn with your fertilizer. It takes the fertilizer right into the watershed. So long as your worst choice in watershed management is actually destroying your local watershed. So John can reduce the amount of lawn that he has. He's going to put something in the places he takes the lawn out of and I recommend trees, I recommend tree groves, planting the trees young so that they can interlock their root systems with each other and become very stable. They're not going to blow over and crush your house or your car in future years, which is another new aesthetic. We're used to looking at trees simply as specimen trees. Well, that's not the way they grow in the forest. They grow with, you know, an interlocked matrix of roots, which it's extremely stable. And it's excellent in managing that watershed. When it rains, the leaves of the trees soften the downpour so that you get soil compaction when the raindrops hit the soil directly. So when they hit the canopy, the tree softens that. And then you just get it dripping. And it allows the water to infiltrate before it runs off.
John Bailer
Well, I feel like I should leave right now. You know, I mean, this is really something that's exciting to me. And I think that it's really this change of perspective on what you hope to achieve in a lawn and what you hope, what you hope to do. I know that you've also made the point that it's not, it's not sufficient just to simply have these trees planted, but also kind of the base of the trees are an important part of this story. That there's a landing pad that's associated with trees. Can you talk a little bit about that and why that's an important part of this?
Doug Tallamy
Yeah, and this is the newest thing we're actually looking at. Of course, if the caterpillars were trying to produce to feed the birds in our yard, and by the way, it takes six to 9000 caterpillars to get one clutch of chickadees to the point where they leave the nest. So you need plants like oaks that are making a lot of caterpillars. While these caterpillars are up on the tree, most of them do not complete the development on the tree. They finished growing as caterpillars, and then they dropped from the tree. And they've got to burrow underground to pupate, or they spin a cuckoo in the leaf litter that's under the tree. And of course the way we landscape there is no leaf litter under the tree. We take it all the way we have grass right up to the tree. We mow it with our huge riding mowers compacting the soil, making it very difficult for those caterpillars to get down underneath. So we're recommending now, I'm actually, the grad student is still working on this to find out what the best recommendations are. But a bed under your tree at least as wide as the drip line. Where are you it's a no go zone, you're not going to walk there, you're not going to mow there, you're going to plant there, you're going to have green mulch, living ground covers, so that the the ground is not compact, the caterpillars dropped down, they can easily spend their cocoons or get underground with without any any issue.
Rosemary Pennington
So what has the response been to these efforts? I mean, you said that the Homegrown National Park idea came to you in 2007. And this is something that's been sort of continually growing. And you've had your books coming out. What has been the response to this idea that we can sort of individually work towards conservation? And how have you seen that shift? Since you started working on this?
Doug Tallamy
That's a great question. Because when I wrote Bringing Nature Home, I didn't think anybody would read it. I thought it was a fun exercise. And I could get on with my life. I was wrong. I was wrong about that. And it was just timing. Accidentally, but people are ready to take action. They're distressed at these terrible statistics. The UN says we're going to lose a million species to extinction. You know, and it will hurt humans. People don't want to hear that. What I'm saying is, there's something you can do about it. So the response has been, it's been much faster than I thought it would. I've never had it. I was gonna say I've never had anybody come to my talk and then come up to me afterwards and say you're totally wrong. They wouldn't do that. But what they say is how come I wasn't taught this when I was a kid. How come we're just hearing about this now. All right, we're a little late, but my message is there's plenty you as an individual can do. It doesn't have to cost a lot of money. You can take your time and do it, but you can get started. And you can make a difference. And you can see that difference that is really empowering all these people that felt powerless, and just, you know, the earth is going down the tubes, now they can do something about it. So that's what's getting people to join Homegrown National Park. And the challenge remains: How do we reach all the people that have never heard about it?
John Bailer
Well, you know, I want to, I just want to congratulate you on this brilliant synthesis of lots of decades of research into an action plan that individuals can embrace. I mean, I find myself just just even coming here, you know, to do this recording, you know, going by a golf course going, you know, they could probably leave a good, good bit of their rough with indigenous, you know, sort of indigenous plants versus invasives. They could do this, if they put their mind to it. I, you know, I go by the university, which looks a lot like a golf course, and in terms of the grass presence. So I did have two kind of related questions as a follow up to that. Have you seen changes at the University of Delaware? If you had, have you been able to kind of influence the local practice of some of these really gigantic green spaces? I accept that I have responsibility? Rosemary does as well. So, we, you know, we're with you on that, but what is it that we can do if we have connections to larger entities that have giant green space?
Doug Tallamy
Right? Yes, I have seen changes at Delaware. Delaware's net was never terrible. It had a pretty good percentage of natives. Of course, you know, a campus is designed to handle 15,000 students walking around. And there are places where green spaces are appropriate, for sure, we've got a big mall. And we're not proposing that we get rid of that. But there are a lot of places where we could switch up plants, particularly invasive plants. We did have the big get rid of the burning bush all overthe campus. That was several years ago. I've talked to the landscapers, I've learned a lot about the constraints they have. They had a great native plan that I think was accidental, but all the plants were native. And it was beautiful walking up a stairway, you can see it on either side. And the next year I went by it was all gone. And I said what, what happened? And they said, well, it turned out that it was interfering with a security camera on the roof of one of the buildings aiming at a parking lot, and they can't have anything blocking that. You know, I haven't been thinking about that. But those are responsibilities of a big institution like this that we have to take into account. But we've got a sustainability committee now that we didn't used to have that the culture has changed, enacting it, there are challenges. But you know, if the culture is changing, you try to enact it, you'll get there eventually.
John Bailer
The city that we live in is talking about what does it mean to have, you know, think about rewilding lawns. And the idea that, you know, this is not just a nuisance overgrown plot. But this was a purposeful way of setting up a lawn. So that's something that I've seen even our little town doing, which I'm really excited about. And I know there's a lot of discussions not only just among individuals that are thinking about what they can do, but even what they can do within organizations that they invoke that that are they're interested in. So I want to just sort of thank you for that. And I take hope in that. And I was just curious, you know, are you seeing these glimmers of hope? Do you know what kind of changes you have seen, as you've looked at, at this, the movement, you know, this movement to think about the homegrown national parks? Have you seen this kind of expansion? Have you seen this increase in the area of homes that are being dedicated to, you know, native plants?
Doug Tallamy
You know, there are townships that have changed the regulation on all new plantings on public parks and properties have to be native. And you can see that happen. If you go to a new development, most of the trees that developer puts in are native these days, much better than it used to be. It was 100% bred for pear, and that was that. So you can see that. But what I'm really seeing is a change in interest. And I get this look at that. My own email. I cannot keep up with my email or talk requests, three or four talk requests a day, from people all over the country who want to hear about this. So what they're interested in is the message. I happen to be a deliverer. So I'm getting pounded with that. But I mean, it wasn't that wasn't that way. Certainly wasn't that way 20 years ago, and it but I could see that if I had a plot of all the talk requests over the last 20 years. as it would look like the human population growth rate, so that's a measure right there, the native native plant cells, the demand for native plants far exceeds the supply at this point. And that's a great measure. So, now that there's still a big empty niche, in terms of, I would call them ecological, landscapers or ecological gardeners, because most people do not garden. And we're not going to make them start gardening; they want to hire somebody. And that's great. So right now, they hire their lawn care company, they mow, blow and go, guys, I want to retrain all those people so they can stay, we're not going to put anybody out of business, but a little bit of ecological training and tell them how to do it in an effective way how to use lawn as a cue for care, a mowed strip of lawn outside that new new flower bed. And by the way, when you make those beds under the trees out to the drip line, you've reduced your lawn by a lot. That's how you do that. But lawn is a great cue for care. And so we're not suggesting that you stop mowing your lawn, we're suggesting you have less lawn, the lawn you keep is still going to be mowed and manicured. It's the area where you walk. It's a perfect plant to walk around without killing it. So there are ways to do this that don't seriously impact the culture. I don't think anybody really thinks that four acres of lawn is that attractive. It's a no man's land, you're never out there. There's no kids playing on it. It's just a default that we've fallen into. And then it's a maintenance headache to get that well planted and people won't object.
Rosemary Pennington
Well, that's all the time we have for this episode of Stats and Stories. Doug, thank you so much for joining us today.
Doug Tallamy
Thanks for having me.
John Bailer
This has been outstanding. This is thank you for the good work and for this mission that you're charging us all to embrace.
Doug Tallamy
Well, thank you for helping with the mission because this is how it happens. It's people like you that help get the message out.
Rosemary Pennington
Stats and Stories is a partnership between Miami University's Department of Statistics and media journalism and film and the American Statistical Association. You can follow us on Twitter @StatsandStories, Apple podcast, or other places where you find podcasts. If you'd like to share your thoughts on the program, Send your email to statsandstories@miamioh.edu or check us out at statsandstories.net, and be sure to listen for future editions of Stats and Stories, where we discuss the statistics behind the stories and the stories behind the statistics.