Posts Tagged Douglas Tallamy
Greetings, my fellow native plant lovers!
This post is to alert you to what sounds likely to be an excellent virtual presentation by experts on North American oak species, including how many of those species are declining and how we gardeners can help reverse that trend.
The Zoom presentation will be on Tuesday, November 9 from 7:00 – 8:30 p.m. EST.
For a small fee, tune in to learn much from the folks who know much.
For details, go here.
If you haven’t read Douglas Tallamy’s book, The Nature of Oaks, I highly recommend that you put it on your to-read list. This book is shorter than his others, because he focuses on one tree species – oaks – instead of entire forest and field ecosystems. By so doing, he is more successful at vividly painting a picture of the complex web of life supported by these long-lived forest giants.
A White Oak’s Tale
To tell the story of oaks, Tallamy centers his tale around one oak tree, likely planted by a blue jay as an acorn several decades earlier. Every chapter chronicles one month in the life of the tree. The entire book is worth reading, but with autumn’s recent arrival, I want to focus today on leaves – the ones discarded by deciduous trees about this time every year, including most oak species. When left alone as Nature designed them to be, these fallen leaves form what Tallamy rightly describes as “priceless litter.”
Magic Beneath the Trees
March is the chapter in which Tallamy tells readers about the magic of fallen oak leaves (He spent his October and November chapters on acorns). As an entomologist, Tallamy is better acquainted than most with the millions of insects and other creatures – most quite tiny – that spend their lives in leaf litter. Soil ecologists call these creatures detritivores. They consume dead plant parts or the bacteria and fungi that help break down plant cellulose in fallen leaves. Dozens of species of moth caterpillars are part of this mix; they eat dead leaves instead of green ones. Of course, these creatures are also eaten by detritivore predators, which number in the hundreds of species. These leaf-litter dwellers provide a critical function by recycling nutrients in dead leaves back into forms plants can absorb via their roots.
All fallen leaves contribute to this mostly unseen web of decomposers critical to nutrient recycling that fuels all life. But oaks, Tallamy tells us, create leaf litter that sustains decomposer populations better than all other tree species. The 700,000 leaves that fall from a mature oak tree decay more slowly than those of most other species, providing ideal litter for up to three years. Decomposers need consistent conditions to survive. Bare soil cannot sustain them; it lacks the nutrients and even moisture levels they need. Slowly decaying oak leaves piled beneath their mother trees provide ideal conditions for the occupants of this intricate food web to perform their magic.
Water for Tomorrow
Tallamy notes that a thick carpet of leaf litter also acts like a sponge during rains. Instead of running off bare ground into storm drains, raindrops soak into leaf litter, which is especially beneficial during heavy rains. Tallamy notes that almost all of a 2-inch downpour – more than 54,000 gallons/acre – is absorbed by leaf litter in an oak forest. Slowly, that water seeps down into the water table, where we and the plants can use it in the future.
While that captured downpour is seeping through the litter, it is purified. Excessive nutrients (for example, runoff from overfertilized lawns) and pollutants are captured by the litter, allowing clean water to filter down to the water table. Instead of flooded streams full of pollutants and eroded soil, clean water slowly seeps downward, replenishing streams downhill gradually, ensuring that flora and fauna relying on those aquatic environments are not disrupted.
More Oaks for More Magic
Tallamy’s message in this book is straightforward. He asks that we all plant oaks appropriate to our region now. It is true that oaks planted now will not mature in our lifetimes, but that is not a reason not to plant them. Gardeners know. We plant for our grandchildren. We plant to enrich habitats for native wildlife. We plant to heal our deeply wounded planet. We plant for the magic created by our vision and effort – not just oaks, of course, but yes, definitely oaks too.
This fall – the ideal season for planting trees and shrubs in the Southeastern Piedmont – please do plant some oaks and other native trees and shrubs. But there is something else you can do that will help. Stop destroying the leaves your plants return to Mother Earth this season. Leave those leaves in place wherever possible. If you must move them, move them gently, to minimize damage to the tiny creatures using those leaves.
Leave Your Leaves
In my yard, wherever practical, I simply rake fallen leaves around their donor trees. In the few areas where I’m still maintaining a “lawn,” I gently rake the leaves around nearby trees. I’ve created a wonderful, increasingly spongy leaf litter bed in my front yard over the last two years by raking about half of the fallen leaves from a massive southern red oak around two ornamental trees. Their leaves also contribute to the litter, but it is definitely those slowly decomposing oak leaves that have created a magically moist, fertile bed into which I’m now adding native ferns and spring ephemeral wildflowers.
Store-bought mulches cannot substitute for leaf litter mulch. They don’t contain the nutrients the millions of detritivores need to survive. It is past time for us to discard old landscaping practices that promote military neatness. Leaves are not the enemy. They are our salvation.
My local Audubon chapter (New Hope Audubon) is currently conducting a wonderful program in collaboration with Triangle Community Foundation and Keep Durham Beautiful, Inc. to promote preserving our leaf litter in place. It’s called Leave Your Leaves. The campaign provides brochures, posters, and yard signs promoting this program. You can read all about it here.
Even if your aren’t a Durham, NC resident, please consider visiting the Pledge To Leave Your Leaves link and signing the pledge. The grant that provided funding for this effort is tracking the number of folks who sign the pledge as a measure of the campaign’s success. If this campaign is successful, it will be easier to win future grants for additional environmental education programs.
Learn More About Healthy Yard Alternatives
Next Thursday, October 21, one of my area’s local conservation organizations (Chatham Conservation Partnership) is holding its quarterly meeting. It will feature several speakers presenting information on healthy yard alternatives. The good news for all my readers is that this meeting will be virtual. If you have the time and a decent internet connection, you are welcome to register and attend the meeting at no cost to you. For details on the meeting and how to register, go here.
A big step toward bringing the magic of a healthy ecosystem to your landscape is leaving fallen leaves in place to shelter the millions of tiny creatures who need them. They, in turn, feed plants with the nutrients they recycle. And the plants feed us all.
Bring back the magic. Leave your leaves.
Kermit the Frog’s well-known song about the travails of being green was about the sense of isolation that comes from being different from other folks. I think it applies equally well to the challenges facing the Green World. These challenges are delineated in detail in Douglas Tallamy’s latest book: Nature’s Best Hope: A New Approach to Conservation That Starts in Your Yard.
In his book, Tallamy’s frustration with humanity is frequently evident. The introduction and first four chapters provide a vast amount of research-based data on how and why Planet Earth’s ecosystems are in imminent peril. His conclusion is inescapable and direct: the actions of humanity are responsible for the destruction of the natural world upon which all life relies.
In the introduction, he categorizes people into three groups: animal-lovers, plant-lovers, and the utterly indifferent. The categories reflect his strategy for reaching each of the groups. For animal-lovers, he explains their critical dependence on plants. He shows plant-lovers why animals, especially insects, are essential to the survival of most flora. And for the indifferent, “the hardest group of all to engage,” he did his best, he says, “to explain why we will lose humans if we don’t preserve the plants and animals that keep our ecosystems healthy and sustaining.”
Dr. Tallamy’s solution to the ongoing demise of life on Planet Earth is a concept he calls Homegrown National Park:
“What if each American landowner made it a goal to convert half of his or her lawn to productive native plant communities? Even moderate success could collectively restore some semblance of ecosystem function to more than twenty million acres of what is now ecological wasteland.”
By restoring functioning native ecosystems to our landscapes, he says, we will be creating a far larger national park system than currently exists, where native animals and plants can flourish. And it is a park we will be able to visit whenever we like by simply stepping outside our homes and offices. It is a wonderful vision, reminding me a great deal of a notion I helped develop and continue to pitch for my region called Piedmont Patch.
Tallamy does not introduce his Homegrown National Park concept until chapter five. His opening chapters provide a brief history of earlier conservation efforts and begin to offer reams of data interspersed with explanations of underlying scientific ecological concepts as he proceeds to build his case according to the standard scientific writing approach. After chapter five, he offers four more chapters full of data-based factoids and solidly reasoned arguments on ways to rebuild carrying capacity and the impact of invasive, non-native species.
Here’s a factoid from chapter six: A massive scientific study called the Millennium Ecosystem Assessment was published in 2005 and concluded then that by the turn of the century (20 years ago), “we had destroyed 60 percent of the earth’s ability to support us.” That factoid should make anyone who loves their children and grandchildren swallow hard. Alas, it is buried in the middle of a chapter, as are many other staggering bits of information, where only a careful reader will ever see it.
Chapter seven is on invasive non-native plants; he calls them alien plants. As someone who has been sermonizing to anyone willing to listen about the negative impacts of these invaders for 25 or so years, I found this chapter helpful, because Tallamy succinctly dissects every point made by those who would have us believe that these invaders are no big deal, just Nature being Nature. Be assured, I will have his well-constructed arguments at the ready the next time someone tries to persuade me about the “benefits” of invasive non-native plants. Here’s just one of his very helpful explanations on this subject:
“Every time a native plant is removed from an ecosystem, or even diminished in abundance, populations of all of the animals that depend exclusively on that plant are also removed or diminished, as are the natural enemies of those species. In sum, then, at the local scale – the scale that counts ecologically – invasive plants typically decimate local species diversity, and claims to the contrary have not been supported by rigorous field studies” (emphasis mine).
It is not until chapter eight, Tallamy’s chapter on the critical need to restore insect species, that he finally offers a key piece of practical information on helping landowners restore native plants to their properties. He explains the concept of “keystone plants,” the species in a given ecosystem on which the greatest percentage of other ecosystem members rely. For example, when looking at which plants support the most caterpillars, the larval forms of moths and butterflies (Lepidoptera), he and his research assistant discovered that “wherever we looked, about 5 percent of the local plant genera hosted 70 to 75 percent of the local Lepidoptera species!”
Tallamy therefore advises that it is essential to plant keystone species appropriate to your area when you decide to restore native plants to your property. His research assistant, Kimberley Shropshire, spent a year compiling a massive database that identifies which insect species rely on which plants. This database has been used by two different conservation organizations to develop free applications for the public to use when planning native restorations of their properties. Tallamy buries this important (to my mind, anyway) bit of information in the middle of chapter eight.
After you enter your zip code, these applications generate lists of native plants suitable for your area, and the lists are ordered, so that keystone species – the plants critical for supporting the most insect species – are listed first, encouraging you to include them in your design. A few pages later, Tallamy explains why this is critical to the successful creation of a functioning ecosystem on your property: “A landscape without keystone genera will support 70 to 75 percent fewer caterpillar species than a landscape with keystone genera, even though the keystone-less landscape may contain 95 percent of the native genera in the area.” In other words, you’ll be planting a pretty native landscape of no use to native birds and other wildlife if you omit keystone species from your design.
The two applications based on Shropshire’s research are:
- Native Plant Finder, developed by the National Wildlife Federation, and
- Plants for Birds, developed by the Audubon Society
In chapter ten, Tallamy explains why he thinks his concept, Homegrown National Park, will work. He suggests that reasoned arguments and education will turn the tide with HOAs, which is what I would expect a man of science like Dr. Tallamy to believe. He’s not entirely wrong. I know of a couple of local HOAs that have been slowly persuaded on the merits of native plant landscapes. Scientific arguments were part of the process, but much emotion-based persuasion was also involved. I believe financial arguments are also critical to persuading HOAs and landowners, and Tallamy ignores this aspect entirely. He also doesn’t mention the need to persuade the real estate and horticultural industries that native landscapes can still be money-makers for them.
In his final chapter, Tallamy gets around to explicitly listing ten steps landowners can take to make Homegrown National Park a reality. It is a short chapter, because, I imagine, he expects that readers have already digested the carefully laid out research and arguments in the previous 204 pages. They are solid, easy-to-implement steps. I hope and pray his notions take hold and sweep the nation.
However, unless many of us who already have a decent grasp of ecology and native plants and animals make Tallamy’s book a jumping-off point for persuasion-based presentations of our own, I fear that the vast majority of Americans in his third category – the utterly indifferent – will not be moved to even read the book.
Let me be clear. In my estimation, there is nothing wrong with the content of Tallamy’s book. His research and conclusions are rock-solid. But as a professional writer and editor of many decades, it is my opinion that this book would have benefitted greatly from a developmental edit that could have shaped its contents into a more persuasive and accessible form specifically targeted to his most challenging audience – the utterly indifferent plant-blind humans who don’t see or appreciate the natural world the way he does, the way I do, the way most of my blog followers do.
Yes, this book gives us Greenies more ammunition for our arguments with HOAs and neighbors; the Frequently Asked Questions section at the back of the book will be especially helpful with that. But will this book persuade the indifferent? I fear it is unlikely.
On this Earth Day and every day, it’s not easy being green, as any plant, hungry caterpillar, or ecologically aware human will tell you. Tallamy’s new book provides us with important information to share with those indifferent to Nature’s wonders. But in my estimation, on its own, it is not a book that will persuade those still blind to the natural world to join the green side. I very much hope I’m wrong.