‘NATURE’S BEST HOPE’ is the title of University of Delaware professor Doug Tallamy’s new book, and the subtitle reads like this: “A New Approach to Conservation That Starts in Your Yard.” In other words, you and I are nature’s best hope. Our actions count, and they add up to counteract a fragmented landscape and other challenges to the survival of so many critically important native creatures and the greater environment we all share.
Doug Tallamy’s 2007 book, “Bringing Nature Home,” (Amazon affiliate link) has been, for many of us, a wake-up call into the entire subject of the unbreakable link between native plant species and native wildlife, and now with more than a decade of additional research insights, he goes further in “Nature’s Best Hope.”
Read along as you listen to the February 10, 2020 edition of my public-radio show and podcast using the player below. You can subscribe to all future editions on iTunes or Spotify or Stitcher (and browse my archive of podcasts here).
Plus: Enter to win a copy of the new book by commenting in the box at the very bottom of the page.
‘nature’s best hope’ q&a with doug tallamy
Margaret: Congratulations on the new book, Doug.
Doug Tallamy: Thank you, Margaret. Pleasure to be here.
Margaret: Big, big, big work. [Laughter.] A lot of work.
Doug: Yes, but I picked at it over the years.
Margaret: Yes, but you should see my pages of notes–as I was reading I was scribbling away, “Oh this, oh that, oh this.” So I want to ask you about some of those things. With the new book, you’ve kind of given each of us an assignment, to help create what you call Homegrown National Park. So can you kind of explain that to us?
Doug: Well, the idea came to me when I was looking at the area of this country that’s in lawn—which doesn’t accomplish any of the ecological goals that we have, and it’s the size of New England that’s in lawn at this point. It’s well over 40 million acres, and I said, “Well what if we cut that in half? We’d have 20 million acres to work with.” And then I started looking at the size of existing national parks, and it turns out that almost all of the big ones in the lower 48, if you add them all up, it’s still less than 20 million acres. So if we call this entity that we create in our yards Homegrown National Park, we actually can create viable habitat that will be bigger than our national parks combined.
And I call it homegrown because we get to enjoy it right at home. You don’t have to go fight the traffic jams in Yellowstone. And it’s true, it’s not going to be as spectacular as Yellowstone, but you also get privacy, you get the benefits of being able to interact with nature at your own time, your own pace. It’d be great for your kids. So there’s a lot of things that you actually can’t get from an official national park that we could get at Homegrown National Park.
Margaret: Right, and early in the book you say, “We will not succeed if we confine our conservation effort to patches of protected areas.” So if we think that what the government or whatever has done, these big public spaces, are going to do it—to offset the issues that we’re facing—it’s not going to, is it?
Doug: No. I mean, and time has proven that. We’ve had parks for a hundred years now, but they are too small and they’re too isolated from each other, and there’s actually a steady drain of species from these areas for those reasons. Eighty-six percent of the country east of the Mississippi is privately owned, and 83 percent of the entire country is privately owned. So we have to include private property in our future conservation goals.
Doug: It’s too big a chunk of the U.S. to just ignore. And that again brings the private land owner back into a critically important position in the future of conservation.
Margaret: So throughout the new book you kind of tell us the why and the how, and then … Spoiler alert: You sum it up in the final chapter in a really focused sort of 10-mandate action plan—things like “shrink the lawn” and “remove invasives” and so forth, and we’ll touch on all those, but maybe not in order.
First I want to dip into a subject that really caught my attention. Early in the book you say that we have to … the goal is “to turn our planted landscapes into effective biological corridors that are big enough for reproduction.” So can you explain that a little bit, too, because I think that’s important for people to visualize, and you hinted at it a minute ago. [Above, from the book: Grass paths between layered native plantings, such as this one at Mt. Cuba Center in Delaware, allow for foot traffic, but massive swaths of lawn cannot support ecosystems.]
Doug: Well we do have habitat that is out there, those small, fragmented habitats, whether they’re protected or not, they do exist. But in between those habitats is what I would call a no-man’s land that’s not designed to support … very little plant life there, almost no animal life. And things that are going to exist in the future have to move between the protected areas in order to exist. So that’s a recipe for failure in the long run.
What we have to do, since we own the land in between those habitats, we have to replant them with enough viable plants that … and by viable, I mean the ones that are actually performing the roles we need them to perform so that we’re creating biological corridors that connect those habitat fragments. And if they’re connected, they’re no longer isolated, they’re no longer fragmented; they’re much bigger.
The biggest reason that species disappear from little habitat fragments is that their populations within those habitats are too small. Just random fluctuations of populations will cause them to disappear over time randomly. So if you connect those habitats, again, they’re not isolated, they’re not as small as they used to be, and the more we connect them, the bigger they are, and the effect of tiny population size will disappear.
Margaret: So all of this to create these biological corridors big enough for reproduction, to grow Homegrown National Park, etc.—this hinges on locally appropriate native plants being made abundant. And last time you and I spoke, we talked about it’s not just any native plant, again it has to be locally appropriate, but we talked about cultivars of native plants versus the straight species, and I’ll link to sort of the detailed story in the transcript of how those differ, sort of like a purple-leafed version of something or variegated versus the straight species with the green leaves, and how those might not be as good and so forth.
Since the previous book, in the time since then, you’ve helped create … It used to be a real mystery: what was the right plant? “Native” might be native to Wisconsin, but I live in New York. Do you know what I mean? It was confusing, and you’ve helped create databases that are searchable by zip codes of appropriate plants. So we can find this out now, how to make a plant palette.
Doug: That’s right. We have a tool on the National Wildlife Federation website called Native Plant Finder.
Doug: You go there and put in your zip code and the best plans for your county will pop up. They’re ranked in terms of their ability to support food webs. So right in order you have the best woody plants and the best herbaceous plants. So it’s not a … you don’t have to guess any more about what plants are going to perform well in your county. A very handy tool that takes away the guesswork.
Margaret: Right. Another of sort of these tenets at the back of the book that I loved, and this is one that I’ve only the last few years really learned about at all, is it says to “create caterpillar pupation sites under trees.” And this kind of ties back to Chapter 8, which might’ve been my favorite chapter of the new book, the chapter is called “Restoring Insects, the Little Things That Run the World,” a phrase from E.O. Wilson. You talk about our insane war on insects and I want you to kind of proselytize a little bit and tell us why to stop hating bugs, hating insects, so much. [From the book, above: A Carolina chickadee with caterpillar; the bird must find thousands to rear one clutch of young.]
Doug: O.K., well the reason to stop hating them is because we won’t exist on this planet without them.
Doug: So if we succeed in our war of eliminating insects, we’re actually killing ourselves. And E.O. Wilson … we’ll go back to him, back in 1987 wrote a paper called “The Little Things That Run the World,” and talked about what would he envision a world that had no insects. What would happen to everything else if insects disappear? And a number of things would happen. First of all, 90 percent of our flowering plants would disappear, which would drastically change energy flow through our ecosystems. In other words, it would collapse the food webs that support animals—our birds, our reptiles, our mammals, and our amphibians. They would all disappear.
Doug: Our decomposers, the insect decomposers would be gone. So the rapid turnover of nutrients that recycles what plants need to grow would end. And his conclusion was that humans would not survive those changes. So the little things that run the world run us as well. We are an integral part of the world. We depend on it and we cannot selectively destroy the things that we decided we don’t like, and our distaste of insects is not fair. It’s based on just our interactions with very few species of insects, the ones that transmit diseases, things like mosquitoes and ticks. Ticks aren’t insects, but we’ll throw them in.
Margaret: Right. [Laughter.]
Doug: And then of course our agricultural pests, and we say, “Well that’s all insects. We’ll just get rid of all of them.” But big mistake; we can’t afford to do that.
Margaret: No. When I give lectures and I come to the slides that show my beloved moths [below] and other creatures that I love in the garden and I’m fascinated by, I always say to people, “I want you to suppress the wish to squish, and stop the rush to crush.” And everybody starts laughing, but it’s like you have got to give them mnemonic devices to get over this mania about killing everything.
So a minute ago I’ve mentioned that that one of the mandates being “create these caterpillar pupation sites under trees” and so forth, and that is about how sometimes there are smaller changes, maybe not planting anything, but a difference in how you take care of existing plantings, or your fall cleanup, or how you prune an elderberry shrub. There were a lot of those ahas in the book that I really loved, and I wonder if you could explain a couple of these sort of cultural changes that we can make that can really make a difference besides planting new things. [Below, a few of the moths at Margaret’s garden, clockwise from top left: painted lichen moth, Pandorus sphinx, tolype, and spiny oak slug.]
Doug: Right. This is something we’ve just started to think seriously about.
Doug: I’m going to use the insects, the caterpillars that use oaks in my county, Chester County, Pennsylvania, as an example. There are 511 species of caterpillars that use oaks where I live. Well, a few of them complete their life cycle on the tree, so things like the polyphemus moth. The caterpillar eats the leaves, turns into a cocoon and hangs from the branches, the moth hatches out and then lays more eggs, and everything happens on the tree. But 94 percent of that 511 species—I think it’s 480 species—drop from the tree and complete their life cycle either in the ground, they’ll tunnel into the soil underneath the tree where they spin a cocoon in the leaf litter under the tree.
And you can see where I’m going here. The way we plant our trees, we don’t allow any leaf litter to be under there and it’s usually hard, compacted soil with lawn that we mow. I mean it’s really a no-man’s land for any caterpillar dropping out of the tree, which means we’ve created an ecological trap. We call in the moths with these attractive trees, they lay their eggs on them, and then all their caterpillars end up dying before they become adults.
So if we’re looking for reasons why insects are disappearing, that would be just one, but it’s an important one because when you look around the landscapes, how many trees actually have beds under them, where people don’t walk, where the caterpillars could complete their life cycle?
And just to continue the thought, why do we want the caterpillar to complete their life cycle? Because they are an essential component of the food webs that support all the other creatures, particularly our birds, and we’ve looked at this. In terms of insects, caterpillars are the most important group in transferring energy from plants to other organisms. They’re eating more plant material than any other type of insects and more things eat them, and that’s how the energy from the sun moves through food webs. Most animals don’t eat the plants themselves, they eat something that ate the plant, and that something is typically caterpillars. So we have to design landscapes that support those caterpillars or the energy flow that supports the rest of life is stopped.
Margaret: And we have to take care of those landscapes, as you’re saying, in a manner that does not disturb their life cycle, their successful reproductive cycle. So in the fall, let the leaves lie under those oaks as much as is as safely possible. Let them lie. Don’t clean them up too soon in the spring, either. I’ve been told by people from Cornell and elsewhere, wait until we’ve got a week of 50-degree-plus days until everybody’s kind of gotten out of underneath the leaves, hopefully, hopefully. Don’t clean up the … don’t do the shredding and the mowing right away, because you take their habitat away. [More on saner fall-cleanup regimens.]
Doug: Yes, if you create a bed, a big bed under your oak tree, and that’s where you do your spring ephemeral gardening, you never have to clean up those leaves to the extent that we’re used to. Let them nestle down to the ground. The plants come up right through them. They’re the perfect mulch. They’re transferring the nutrients from that tree back into the soil. They’re protecting the soil ecosystem, which actually has more species than the above-ground ecosystem. They’re holding water on the site when it rains hard. The leaf litter’s great in terms of soaking it up like a sponge and not letting it run off. So when we “clean it up,” we’re getting rid of all those benefits.
Doug: Including the cocoons that we say the first week of March, they’re not all out by then. They’ll emerge at different times through the … some of them only have one generation a year and they may not come out until July. So the more we can leave in areas on our property, the better off we’ll be.
Margaret: Yes. So among kind of that punch-list action plan toward the back of the book, which starts with again “shrink the lawn,” which we’ve talked about, and there’s a couple of sort of commandments for making a Homegrown National Park that are about plants. One is “remove invasives,” and I think we’re going to have to have a whole separate conversation about that, because boy, oh boy, I look around where I live and I drive around–it’s unrecognizable, what’s lining our roadways. So that’s a whole separate thing, and we can do that on our own properties.
But then the next three tips are plant-specific, and you say “plant keystone genera,” and so these are some of the ones like the oaks you were just talking about that are the heavy hitters; that have the most interactions. [Above, from the book: Most suburban yards are mostly lawn, and devoid of native plants.]
Doug: Right. We have found that about 5 percent of our native plant species are producing about 75 percent of the food, and this is a consistent pattern all over the country. So if you construct a landscape that doesn’t include … I call them keystone species. If you don’t include them, then the food web collapses, just like a Roman arch with the keystone in the middle. You pull the keystone out, it falls down. So these plants are vital.
Then you can diversify once you have them in your landscape, but you can think of them as the 2-by-4s that are holding up your house. If you made your house just out of wallpaper, it wouldn’t work. It’d be pretty, but it wouldn’t work very well. So we need those strong, structural plants that are driving the food webs if we’re going to have an ecosystem in our yard that contributes to local ecosystems instead of degrades them.
Margaret: Right, and in that nwf.org/nativeplantfinder, in that zip code-based research tool, we can find out some of the powerhouse plants for our areas, yes?
Doug: Well they’re ranked. So they’re ranked in terms of their ability. The top ones are the best. [Above, oaks, willows, Helianthus and goldenrods are powerhouse performers.]
Margaret: Yes. Good. O.K., and one of the other things that you talked about in the book was planting for specialists, because some native organisms are more generalist in their feeding habits and some are specialists, and so it kind of stuck in my head: you said “plant for specialists.” Can you briefly explain that approach to us?
Doug: Yes. Well that applies to both the insects that eat plants, the insect herbivores, and also many of our pollinators, our native bees especially.
Doug: So let’s start with those pollinators. We have 4,000 species of native bees, and many of them can only reproduce on the pollen of particular plants, and it’s usually at the genus level. Where I live, there are about 13 species of native bees that can only reproduce on the pollen of goldenrod. Doesn’t matter which goldenrod, but if you don’t have goldenrod you’ve just lost 13 species of native bees. Even though you might see them go to get nectar from other plants, their larvae are specialists on goldenrod pollen. And you get a similar number with native willows, a similar number with native asters [below, with monarchs], native sunflowers—and I’m not talking about the giant ones grown from seed, I’m talking about the many species of Helianthus that we have around the country. Violet, those are all very, very powerful plants in terms of supporting bee specialists.
Then there’s a whole slew of plants that only have one or two bee specialists on it, but if you don’t have them, you’ve lost those specialists.
When it comes to the insects that eat plants, about 90 percent of them are specialized on one or two plant lineages, and you can always think of the monarch butterflies, a perfect example. If you don’t have milkweeds, you don’t have the monarch, and that is true for most of the caterpillars that are out there.
Margaret: So we plant for them, for the specialists, and the generalists will find something to eat in the mix.
Doug: Right. Generalists can eat many things, but we’re also learning … I don’t want to beat a dead horse here, but even generalists are much more specialized than we think. Often in one area, a generalist that can eat many plants around the country can only eat one or two in a particular place, and if you look at all the plants that are available to these insects, even our most generalized insects can only eat maybe 4 percent of them. So people think generalists can eat every plant. Not even close; not even close.
Margaret: And then there are some … there was one example about fruit in the book that I recall. So you may have a garden that’s full of fruiting shrubs and so forth. Early on in my career I planted a lot of viburnums. I thought that was a good thing for the birds. Guess what? The non-native ones, they usually leave behind the fruit or it doesn’t seem as appealing in a lot of cases, whereas my native viburnums get picked over, and that’s probably just anecdotal observation, but-
Doug: No, that’s real.
Margaret: And there’s different kinds of fruits, and you point out that not all fruit is created equal. So especially pre-migration time when you need to fatten up and get in high-energy food, not all fruit is the same. So some of our non-native fruits that produce in the fall aren’t good for that time. I mean they’re not as good a meal, are they?
Doug: The problem is that for some reason … and people are looking at this, particularly a woman named Susan Smith [Pagano of Rochester Institute of Technology], the fruits from the plants from Asia, and this includes multiflora rose and Oriental bittersweet, Japanese honeysuckle and all those guys, are very high in sugar in the fall and very low in fat, less than 1 percent fat. So in the fall, that’s a problem for birds, because they’re either migrating when they need a lot of fat or they’re going to overwinter when they need a lot of fat in the berries. And that’s where our native viburnums or things like Virginia creeper or our native dogwoods, their berries approach 50 percent fat, and it’s exactly what the birds need. So they do eat non-native berries, but most of the time it’s because there’s no other choice. That’s all we put out there for them. [Above, from the book: downy woodpecker eating native poison ivy berries, which are high in needed fat.]
Margaret: Right. I want to just shout out a couple of the other sort of tenets in your 10 tips at the end of the book, like that we should “network with our neighbors,” because again we’re trying to create this larger than just little polka-dot areas. We’re trying to put together areas and network with our neighbors and educate others in our neighborhood, in our civic association, and so forth.
But there’s one called “build a conservation hardscape,” and that has some really interesting tips and I wonder if we can just quickly list some of them, like how having no lights that are on all night long, for instance, outdoors is a really important conservation thing, and not just because it saves electricity.
Doug: Right. Lights are a major killer of particularly our moths, and research around the world is showing that lights … We have global insect decline, but lighting up the sky at night is one of the major causes of that, and what’s frustrating is most of the time is absolutely unnecessary. If you’re concerned about security—a lot of people say, “I’ve got to have my security lights on”—well then put a motion sensor on those lights so they only turn on when the bad man comes.
Doug: Even easier than that is to change out the bulbs and put in yellow LED bulbs. That’ll save you energy and they’re the least attractive to insects.
Doug: If we did that throughout the country, which would take everybody about 5 minutes, we could literally save billions of insects every season. Very easy change.
Margaret: Yes. There’s a few more in there and we’re running short on time, but covering window wells, for instance, so that small animals like toads [above] don’t fall in and die. Setting our mower blades higher—so that same thing, we’re not killing small creatures in the grass, not mowing at the time of day when everybody’s still hiding in the grass, late in the day, I guess, in the evening. Lots of important tips.
But before we finish, I just want to take a selfish minute to say, last time we spoke, you talked to me about the oaks and you told me about some of the things that you and your wife have done on your property with the oaks, and I wanted to tell you that I’ve been listening [laughter] and I hope readers are listening. I’ve been un-mowing for a couple or a few years, another area up on the hillside in the sort of field above my house, and the oak seedlings are growing and I’m going to thin them to the best ones and I’m going to have some more oaks at my place because of you.
Doug: Wonderful, wonderful.
Margaret: So it made a difference to hear, because I was overwhelmed also, even as much knowledge as I have, in knowing what plants … and you talked about native willows and I’m upping the quotient of those, and you talked about others of these keystone plants, and I think that’s just such an important message to help people to feel empowered.
Doug: I’m going to give you quick example from our yard. I’ve been counting the moth species at our house. We’re up to 905 species.
Doug: About 250 of them are associated with our oaks, which is only 3 percent of the plant diversity on our yard.
Doug: So that just shows you how powerful those oaks are.
Margaret: Wow. Well I loved the new book, “Nature’s Best Hope,” and thank you so much. Thanks for making the time, Doug, really.
Doug: Oh, you’re welcome.
more from doug tallamy
(Photos except powerhouse plan collage, toad and moths, are by Doug Tallamy, from “Nature’s Best Hope,” used with permission.)
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MY WEEKLY public-radio show, rated a “top-5 garden podcast” by “The Guardian” newspaper in the UK, began its 10th year in March 2019. In 2016, the show won three silver medals for excellence from the Garden Writers Association. It’s produced at Robin Hood Radio, the smallest NPR station in the nation. Listen locally in the Hudson Valley (NY)-Berkshires (MA)-Litchfield Hills (CT) Mondays at 8:30 AM Eastern, rerun at 8:30 Saturdays. Or play the February 10, 2020 show using the player near the top of this transcript. You can subscribe to all future editions on iTunes/Apple Podcasts or Spotify or Stitcher (and browse my archive of podcasts here).