Archive for category Invasive Exotic Species
All gardeners know that fall is for planting. It also marks a rise in wonderful presentations on gardening-related subjects. Case in point: the amazing Debbie Roos, one of the agricultural extension agents for Chatham County, NC, will give what promises to be a great webinar from 6:00-8:00 p.m. on November 10.
To read more about Creating Wildlife Habitat with Native Plants and to register to virtually attend, visit the link. You will learn much, I promise!
For those of you deeply interested in invasive plants, the expert members of the NC Invasive Plants Council will be virtually gathering for two half-days of presentations on November 9-10. Presentations can get a tad technical for the layperson, but you will learn about control methods, which species the experts are most worried about, and other useful information.
You can attend for free, but please consider joining the group to help fund their efforts. To see the agenda and register, go here.
My apologies for my prolonged absence. It’s been a long, strange summer — for most of us, I imagine. I’m planning on being here more reliably henceforth.
As you likely know, today is the last full day of astronomical summer. Finally in my yard today, we are getting measurable rain — a weather phenomenon that has been absent for over two months. Folks 30 miles to my east have experienced flash floods more than once during that time. My yard however, has been a dust bowl. You know it’s bad when tree leaves hang limp even in the early morning. It hurt me to walk around and see them suffering.
Today, however, perhaps to usher in tomorrow’s autumnal equinox, our skies are finally dark. Occasional showers have reawakened the long-dormant rain gauge. I imagine plants and animals alike are reveling in the water as much as I am.
This summer was tough on native butterflies. Posters on the local email butterfly group I follow have been lamenting all summer on the low numbers of lepidopterans observed. They’ve also commented on the low numbers of spiders. I’ve noticed both of these phenomena in my yard too. There was a spell of about six weeks when the only butterflies I saw were a couple of Pearl Crescent butterflies like the one above.
Native solitary bee numbers were variable. For the first time in forever, I had both American bumblebees and brown-belted bumblebees abundantly present on my flowers. Solitary wasps were also present in great numbers, and I think this may have been bad news for my caterpillars. Every time I’d spot a Monarch caterpillar or a black swallowtail caterpillar on my plants, the next day, it would be gone. Wasps were everywhere, searching every leaf, so I suspect they were catching the caterpillars to bury in their nest tunnels to feed their hatchlings. It could have been birds too. They were here in relatively normal numbers this summer, I’m happy to report.
Besides the drought, the worst news of the summer for my local Green World was the appearance of a new invasive exotic species. Giant Resin Bee, also called Sculptured Resin Bee (Megachile sculpturalis) is native to Eastern Asia. It was apparently introduced to the US in the 1990s, and showed up in significant numbers at my house this summer. It’s a kind of carpenter bee, but unlike our native carpenter bees, it doesn’t create its own nesting tunnels. Instead, it appropriates tunnels belonging to other insects, especially our native carpenter bees. The link above provides all the information you need to know about this recent invader.
I noticed these bees about mid-June when they were all over my blooming Common Milkweed and Narrow-leaved Mountain Mints. These are big bully bees. They would land on flowers hard, shoving all native pollinators aside as they claimed nectar and pollen for themselves.
I took a photo and posted it to my iNaturalist account in hopes of learning the identity of what was at that point a mystery bee. I got an answer very quickly. The entomologists on iNaturalist must have been watching for reports. In fact, just a few days after my Giant Resin Bee photo was identified, I got an email via iNaturalist from an entomologist in Vienna, Austria working on her Ph.D. on this species. She is doing DNA analysis on this species collected from all the parts of the world to which it has spread. Her goal is to determine migration patterns of the bees, based on DNA analyses of populations. She asked me if I would be willing to collect bees, freeze them to preserve their DNA, then give them to a colleague in the US who would collect them and ship them to her for analysis. Of course, I said yes — citizen science for the win!
I spent a number of hours patrolling my flowers to collect as many bees as I could for the study. I became adept at spotting the males; they have a characteristic yellow “mustache.” There’s a good photo of this feature in the link above. The females are bigger, less numerous (thank goodness), and showed up about a week after the males appeared, which, the entomologist from Vienna told me, is normal.
All told, I collected 40 Giant Resin Bees, mostly males, which completely flabbergasted Julia (the entomologist). She had never heard of anyone seeing, much less collecting, that many bees. And I think, alas, I know why. There’s one last detail I haven’t told you yet.
Giant Resin Bees evolved in the same part of the world as kudzu, and it is what is called an “effective pollinator” of that plant, which means that when Giant Resin Bees visit kudzu flowers, the flowers get pollinated and set seed. This is a nightmare scenario for those of us living in the Southeastern United States. Up to now, kudzu — although a notorious invasive species — has not been as big a threat to native ecosystems as many other non-native invaders, because it only spread vegetatively. Our native pollinators were not effectively able to pollinate kudzu flowers because they didn’t evolve with them, so kudzu was only rarely setting seed. Thus, all we have had to worry about — as if that wasn’t enough — is the terrifying vegetative growth rate of kudzu, which grows several feet per day during our growing season. But if it starts setting seed reliably, and those seeds spread out via animals and/or natural weather processes and germinate, the potential for kudzu world domination explodes!
When I learned of the Giant Resin Bee-kudzu link, I wrote my favorite local expert, Johnny Randall, Director of Conservation Programs at the North Carolina Botanical Garden, to ask him how worried I should be about kudzu world domination. He told me that if the Giant Resin Bee continues to spread and pollinate kudzu, the only thing standing between us and a Kudzu Apocalypse is a native weevil with a fondness for eating kudzu seeds. I never thought I’d be praying on behalf of a native weevil, but this kudzu-seed-eater has my full support!
Why did I collect so many Giant Resin Bees on my kudzu-free <knock wood> five acres? Because my “neighbor” across the road from me permits kudzu to roam freely over most of his multi-acre property. If not for the busy road that separates us, kudzu vines would have certainly crossed over to our yard years ago. My guess is that kudzu flowers drew the Giant Resin Bees to my neighbor’s yard, then some flew across the road and discovered the abundant native flowers blooming in my gardens.
You’ll see in the link further up that local extension agents are asking folks to report sitings of this bee. They don’t really have a handle on how many are here in the Southeast. I’m betting that if you live near kudzu like I do, these bees will be on a flower near you next June. Be sure to report them if you see them. Meanwhile, I’ve still got 40 frozen Giant Resin Bees in our freezer awaiting pickup by a local entomologist.
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.
I know I’m not the only person out there who had a rough summer. Trials and hiccups aplenty came at me for many months. I could not wait for the autumnal equinox in September, thinking the season change would bring relief. Instead, it brought the worst drought experienced by my five acres in twenty or so years. Unrelenting heat and the absence of rain left the creek bordering our property completely dry, except for deeper pools, where great blue herons happily devoured fish trapped therein.
The contrast between this September and last year’s relentless hurricane rain flooding could not have been more stark. Climate change smacked me and my land hard two years running.
Substantial Damage to Our Protected North Slope
In June, the antique septic field associated with our 50-year-old house was replaced with a new one. The devastation to my deer-fence-enclosed north acre full of native rhododendrons, magnolias, viburnums, vacciniums, and shade-loving choice wildflowers threw me into a tailspin of depression. Wonder Spouse and I planted these beauties as tiny things – all we could afford – 20-30 years ago. As previous posts here can attest, they have flourished, blooming more wonderfully every year.
Even though we marked off our botanical treasures with flagging tape, even though Wonder Spouse took off two days of work to oversee the trenching, that once-beautiful area was significantly damaged after he returned to his office and I was away at an appointment. On top of that, we were forced to remove a mature water oak before the work began, because it had early signs of heart rot. We couldn’t risk having the tree topple and rip up the newly installed septic field.
That enclosed acre is on a slope, which is great for siting rhododendrons, but when earth is scraped, then compacted, erosion from rare-but-heavy rains quickly created myriad little gullies. Soil washed from hilltop to hill bottom, depositing more than an inch of silty mud. I am not ashamed to admit that I cried for two weeks, mourning the loss of trees and shrubs ripped away by machines, the much-missed shade of the venerable water oak, and the wildflowers obliterated by careless men oblivious to the vibrant beauty before them.
Eradication of Surrounding Forest by Bulldozers
Most of the areas near us that were forest thirty years ago have either already been erased and replaced with monotonous subdivisions, or that devastation is ongoing as I type. Every day, more displaced wildlife from those areas arrives on our land, as evidenced by what our wildlife camera beside the creek captures weekly. A considerable beaver population has been forced on top of the wetland adjacent to our property. Up to now, they had been content to maintain their growing pond on our neighbor’s land, but yet another new subdivision (housing prices starting in the mid-$600s!) has pushed them to expand their dam so that our bottomland is rapidly going under water.
Ongoing Radical Transformation of Our Two-Acre Floodplain/Wetland
That was the third strike against our floodplain this year. The first came in April when deadly Emerald Ash Borers were confirmed to be invading the 37 mature (70+ feet tall) green ash trees that dominate the canopy in that area. The second came in late summer when a plant I had never seen before that had spread over most of the floodplain finally bloomed and I was able to identify it as a non-native invasive plant from Asia that, I’m told, has already overgrown all the floodplains of the NC coast and is now moving rapidly into my Piedmont region. It is called Marsh Dayflower (Murdannia keisak), and it is a nightmare. I never thought I’d type this sentence, but Marsh Dayflower dominance makes me long for the days when Japanese stiltgrass (Microstegium vimineum) was my biggest problem. Strike three – the beavers – are actually using Marsh Dayflower to their advantage. They rip it up, mix it with mud, and pack it between the logs they cut down to build their dams, making the dams even more impervious to the force of moving water than before. This is a mutually beneficial relationship, because when stem segments of Marsh Dayflower are broken, as for example, when ripped up by beavers, every segment grows roots, thereby multiplying this invader even faster.
After two years of epic landscape destruction/alteration, any illusions I ever had about being able to control what happens on my land are entirely dispelled. I always understood that, at best, I was a design collaborator as I tried to work with the native ecosystems on our land. However, the last two years have convinced me that the native ecosystems are almost as ineffectual as I am at managing changes we were never designed to handle. Wholesale eradication of habitats by bulldozers in combination with a growing number of non-native invasive species of animals, plants, fungi, and bacteria and the overwhelming introduction of herbicides and pesticides killing wildlife by the millions if not billions, are completely disrupting the natural processes native ecosystems evolved to handle change. We can’t keep up. Species are dying at record rates. It is enough to make a lifelong gardener want to surrender – almost.
A month or so ago, I attended a lecture by a pair of enthusiastic master gardeners from an adjacent county. They described how they transformed their half-acre home lot into a flowering paradise, bragging that 50% of the plants they have added are native to the southeastern US. To justify planting 50% non-native plants, they quoted an “expert” gardener who states that “just because a plant is native, that does not make it better… Choose the right plant for the spot, no matter its origin.” In an exercise of enormous self-control, I did not argue with them. It was their talk, their intentions were good, and it was not the appropriate setting to object.
But I do object, and the last two years on my land are ample reason why. In North Carolina, master gardeners are trained by employees of land grant universities, mostly North Carolina State University. These are good folks with good intentions, but they serve the agriculture and horticulture businesses in the state. Their top goal is to help these businesses be successful. One way to do that is to help the horticulture industry sell plants. Pretty non-native ornamental plants not eaten by native wildlife because they don’t recognize them as food make a lot of money for the horticulture industry.
[NOTE: One of the finest agricultural extension agents I know has pointed out to me that when they work with home gardeners, their goal is only to make those home owners successful gardeners, not help the horticulture business sell plants, regardless of origin. I did not mean to imply otherwise; I think that may, however, often be an unintended consequence of not providing an ecological framework for gardeners. As I responded to her, when agents keep pushing old thinking (right plant for right place regardless of origin) about how to approach home landscapes, they are not helping to save native ecosystems. In my conversations with agents and master gardeners from other counties, it is clear that most don’t understand the role of native plants in ecosystems. They categorize natives as “thugs,” for example, if they multiply assertively, without understanding the ecological role of such plants in nature. In my opinion, such non-contextualized statements do more harm than good. ]
Fifty years ago, this may not have been a terrible thing. But oh how much our world has changed here in North Carolina in the last 50 years. Expanses of forests and fields that once provided buffers and havens for native wildlife and plants are nearly gone in much of the state. Wildlife species are disappearing. Pollinators are dying from poisons; the birds that eat them are also disappearing. Humans need those ecosystems to moderate air pollution, control erosion, pollinate and protect our crops, etc.
We also have hard data from scientists now that demonstrate that landscapes must contain 70% native plant species to adequately feed nests of baby songbirds. That’s seventy percent, not fifty.
This is not a Drill!
We need every patch of native plants we can introduce on public and private lands not covered by concrete and buildings. We no longer can afford the luxury of filling our landscapes with non-native plants that provide no ecosystem services. We can no longer indulge in 50-year-old thinking. This is not a drill, people. Native plants are our only hope of saving what’s left of our native ecosystems, especially the rapidly disappearing wildlife species.
Only a radical shift in the way we think about our public and private landscapes will serve the future now. It is past time to discard old thinking and focus on saving as much as we can. I pray every day it is not already too late. And I’m not just sitting at my computer wringing my hands in frustration. After my initial depression dissipated, I got busy. With the help of Wonder Spouse and my amazing garden helper, Beth, we have planted many new species and introduced existing natives to new sites opened up by the uninvited changes to our land. Our land had a tough summer and a hard fall, but I’m determined to do everything within my power to make next spring a much better season. I’ll describe some of what we’ve been doing in another post I hope to write soon.
In the meantime, if you care about the future of our planet, especially the rapidly urbanizing area of the southeastern US where I and most of my readers live, if you have children and/or grandchildren, I beg you to empty your brain of the old ways of tending your landscape and join me in the radical changes required to salvage as much as we can of our native ecosystems. It will be different, but more beautiful than ever. Most important, it just might help us all hold on to a healthy, balanced, vibrant world – a fitting legacy for those who follow us.
Those of you who have read this blog for a while may remember when I first wrote about the invasive non-native insect called Emerald Ash Borer here. This insect species is killing almost (maybe all) ash tree species in North America — no joke. It started in areas like Canada and Michigan, and has been marching steadily southward ever since. Its occurrence is widespread in North Carolina. Dr. Kelly Oten, Forest Health Monitoring Coordinator for the North Carolina Forest Service, told me that confirmed sitings are reported for every county around me. The closest infestation she knows of is about 10 miles north of my five acres.
I had read about an experimental program Dr. Oten’s office is using to combat the Emerald Ash Borer (EAB) — the release of a parasitic wasp species native to the same part of Asia where EAB evolved. I believe the wasps used in NC parasitize EAB eggs by laying their own eggs inside EAB eggs. A couple of wasp species that parasitize EAB larvae also exist, as described in a US Forest Service publication on EAB biocontrols here.
I assumed that my little five-acre patch of Piedmont would be too small for this experimental wasp release program, but a forester friend of mine encouraged me to give Dr. Oten a call, so I did. I was delighted to discover that Dr. Oten was interested in the stand of 37 mature Green Ash trees growing on the floodplain portion of my land. However, she cannot release wasps unless she is certain the EAB is present on my land, because the wasps will die without a food source.
I have seen no evidence of EAB damage in my ashes <knock wood>, such as crown dieback and a yellowing of leaves (Here’s a link to a PDF from the Canadian Forest Service containing everything you need to know about detecting EAB damage.), so Dr. Oten suggested that we set up a couple of EAB traps at the appropriate time. That time is early April, because that’s when EAB egg-laying occurs, and it is EAB eggs that the experimental wasps look for to parasitize.
On the morning of April 11, Dr. Oten arrived with two traps to hang on a couple of my ash trees. The traps are shipped flat in pairs that are stuck together by the sticky fly-paper like glue used to snag passing EABs. In the above photo, she has successfully pulled the two purple traps apart and has begun to fold the one she is holding so that the sticky glue is on the outside of the three-sided trap. The traps are purple, she told me, because research shows this color attracts EABs most effectively, perhaps, it is theorized, because young ash leaves often possess a purplish hue.
Besides the EAB-preferred purple color, traps also contain a bag of scent lure that is hung inside the trap. Dr. Oten is holding one of those bags in the above photo (click on any photo to see a larger version). The scent emulates the smell of an ash tree in distress. Many studies have confirmed that plants engage in sophisticated chemical warfare with their insect enemies. In many plants, when a plant is under attack, it emits a scent signifying its distress, which in turn stimulates nearby plants of the same species to begin producing chemicals that may help them repel invading insects. This doesn’t work for the ash trees with EAB, because North American ash trees did not evolve with this insect; thus, they have not developed any defenses against EAB attacks.
After she attached lure bags to the center of the EAB traps, Dr. Oten used the long extension pole in the photo to attach the traps to sturdy horizontal branches on two ash trees at opposite ends of my floodplain. This turned out to be trickier than you might think, because my canopy-size ash trees don’t possess many horizontal branches within reach of the pole. Dr. Oten’s first attempt to hang the trap was unsuccessful; the sticky trap fell into a stand of bladdernut shrubs, thus becoming adorned with bits of bladdernut leaves and flowers. Her second attempt with a different tree was successful.
In the second photo above, you can see bits of bladdernut leaf and flower stuck to the trap. Dr. Oten said this will not interfere with the trap’s effectiveness in luring EABs.
Next, we slogged through the mud to the far side of my floodplain, where Dr. Oten selected a second ash tree suitable for trap-hanging. This operation went more smoothly than the first, and the trap was soon hung.
Dr. Oten explained that EABs are actively flying and egg-laying in my area from early April until about June. She plans to return to my floodplain in about four weeks to inspect the traps for EABs. If she doesn’t see any, she will add fresh lure bags and return in another four weeks. If no EABs are found on the traps during that time period, it is less likely — but not impossible — that EABs have found my ash trees — yet. If she does find EABs stuck to the sticky glue on the purple traps, she will release parasitic wasps into that area.
Note that the wasps are not expected to stop the demise of my ash trees. My understanding is that the introduction of the wasps is part of a long-game biocontrol strategy that may, perhaps decades from now, yield benefits. It is an entomological shot in the dark, as it were.
For me, helping with this experiment is far better than the two alternatives available:
- Doing nothing but watch the ashes decline as the woodpeckers feast on their dying remains full of EAB larvae, leaving behind a floodplain almost fully devoid of its canopy tree cover.
- Having an arborist inject systemic poisons into the trees. Besides the exorbitant expense (37 60-70-foot tall ash trees), the poisons kill any insect that takes a bite out of treated trees. In his classic book, Bringing Nature Home, Douglas Tallamy notes the number of different insect species that rely on native trees for food. For ash species, his number is 150; that’s 150 different insect species that rely on ash trees as a food source. So if you poison your ash trees to prevent EAB invasion, you will also potentially poison at least 150 native species of insects that rely on ash trees. Further, those now-dead insects — mostly caterpillars — would have fed myriad species of nesting songbirds, which also will likely now die from starvation.
You cannot break one link in the chain of life without affecting every other link. I pray every day that humanity figures this out — and acts on that knowledge — before so many links are broken that the chain cannot be mended.
Decades ago, Wonder Spouse and I planted two species of native deciduous holly on our floodplain — a location where all have flourished. These wonderful natives consistently produce abundant quantities of berries that are usually eaten by local birds and passing flocks of Cedar Waxwings by some time in January — sooner if winter weather is more severe. I think the berries probably don’t taste as good as, say, those of native spicebushes (Lindera benzoin), which vanish in late summer as soon as they ripen into scarlet beads that contrast with vibrantly green leaves.
Both spicebushes and hollies are dioecious, which is a fancy term used by botanists that means the flowers of each sex occur on different plants. Thus, if you want your female plants to produce lots of showy berries, you must ensure that a male of the same species is nearby, so that pollen from flowers on male shrubs is deposited by visiting pollinators onto the flowers of female shrubs. I am fortunate to have a neighbor who keeps honeybees, so in addition to the many native pollinators that visit my blooming plants, in spring when the hollies bloom, they are also covered by busy swarms of honeybees from dawn to dusk, thereby ensuring abundant fruit set.
The two species of native holly that I grow are Winterberry (Ilex verticillata) and Possumhaw (Ilex decidua). The latter species is not to be confused with another native shrub often called Possumhaw — Viburnum prunifolium — which is why I always try to insert a plant’s Latin botanical name in my posts. Both holly species can grow to heights of 15-20 feet at maturity, maybe even a bit taller. They both tolerate flooding, routinely moist soils, and even dry soils; they are tough native shrubs. I think Winterberry usually grows taller than Possumhaw, but on my rich alluvial soils, both species have achieved significant sizes. When I planted them, I had imagined shrubs wide at the base continuing to the top, but deer consistently ate the lower branches after we removed the wire cages that protected them during their first few years of growth. Thus, my floodplain hollies look like trees, with trunk bases devoid of branches. Either form is aesthetically pleasing to my eyes.
Every year as the canopy trees on my floodplain discard their autumn foliage, the deciduous hollies growing beneath them take center stage. During early autumn, their red berries mingle with the still-green leaves of the shrubs. But by late November, those leaves have fallen, revealing branches adorned by bright red clusters of berries. I think the visual effect is wonderful. Naked branches permit longer views of my floodplain, creek, and adjacent wetland, while the red berries provide bright pops of continuing color — and, eventually, food for winter-hungry birds.
I am delighted by the diverse number of native birds that visit our five acres of green chaos, and their presence has yielded continuing surprises. One of those is bird-deposited volunteer plants. Seeds are designed to survive travel through birds’ digestive systems; some even require it for germination. In my yard, I discover all sorts of “bird-planted” species growing beneath large trees — often evergreens — where the birds shelter at night and during rough weather. Such areas are prime locations for the appearance of non-native invasive exotic species, such as Asian Bittersweet, Mahonia, and several species of Ligustrum and Elaeagnus.
But those locations also yield volunteers of native plants, likely from fruits eaten off of plants in my yard. Thus, I now have an abundance of spicebush growing on my property; there were none until I planted three over twenty years ago. I’m also starting to see quite a few native Beautyberries now. The biggest volunteer surprise, however, was the appearance of two bird-planted deciduous hollies at the top of our hill just outside the fence that protects our vegetable garden from marauding deer. The two shrubs are growing quite close to each other, their branches intertwining. And most wonderful of all, one is male, and the other is female. I was so stunned when I realized the identity of these plants that I decided to leave them where they appeared. Now, a few years later, they are about 12 feet tall, and the female is so laden with ripe red berries right now that everyone who encounters her gasps in surprised delight.
I suspect her fruit set is especially impressive for two reasons. First, her branches are intertwined with those of the adjacent male plant, so proximity to pollen is maximized. On top of that, my neighbor’s bee hives are less than 100 feet from these plants. These shrubs literally buzz with honeybee activity when they are blooming.
I suspect these volunteers are Winterberries, but I have not tried to verify this. Frankly, I don’t care. I know they are native, beautiful, and beloved by birds — especially a Mockingbird that defends the female shrub against all comers as soon as the berries begin to show color. Every morning, he perches on one of the top branches of the berry-adorned female shrub and demonstrates the versatility of his vocal repertoire for all to hear. He tolerates my proximity as I work in the vegetable garden — as long as I am careful to greet him with respect and avoid lingering too long in front of his winter pantry. It’s a mutually agreeable arrangement.
This past weekend, I walked the floodplain portion of my yard to count the number of Green Ash (Fraxinus pennsylvanica) trees growing on it. Thirty-seven trees – 17 females, 20 males – most between 50 to 70 feet tall are the dominant canopy species in this part of our property, about an acre and a half. My adjacent neighbors’ properties also include floodplain areas that are dominated by Green Ash trees.
I was devastated when I realized how completely Green Ashes dominate the canopy layer of the healthy wetland that I live beside, because in less than ten years – more likely less than five, it is a near certainty that they will all be dead – felled by a tiny green insect from Asia that no one has been able to stop: the Emerald Ash Borer.
The insect has already killed “tens of millions of ash trees in southeastern Michigan alone, with tens of millions more lost in Arkansas, Colorado, Connecticut, Georgia, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Massachusetts, Maryland, Minnesota, Missouri, New Hampshire, New Jersey, New York, North Carolina. Ohio, Ontario, Pennsylvania, Tennessee, Quebec, Virginia, West Virginia, and Wisconsin”. Here’s a link to a current map of infected states that is maintained by the Emerald Ash Borer Clearinghouse (Click on the down arrow to move through time to 2015 and watch how many states become infected). The insect is expected to continue spreading until it has killed every ash tree species in North America.
Southeastern US Ash Species
In the southeastern piedmont region of the US where I live, four species of ash are native. Three are wetland species: Green Ash (Fraxinus pennsylvanica), Carolina Ash (F. caroliniana), and Pumpkin Ash (F. profunda). As is evident on my floodplain, these three are important species in wetlands, and when they are felled by the Emerald Ash Borer, the transformation such areas undergo will be profound. White Ash (F. americana) prefers deep, well-drained soils. Its wood has been used for centuries to make fine furniture, baseball bats, and any other wooden item that needs to be strong and lasting. It has been used extensively as a landscape tree.
Animals that rely on ash trees
Humans aren’t the only living creatures who have relied on ash trees for centuries. According to Dr. Douglas W. Tallamy in his book Bringing Nature Home, ash trees support at least 150 species of moths and butterflies – more than hazelnut, walnut, beech, or chestnut. Moths whose caterpillars rely on ash trees include the Promethea Moth, Apple Sphinx Moth, Fawn Sphinx Moth, Great Ash Sphinx, and Banded Tussock Moth. Butterflies whose caterpillars rely on it include Eastern Tiger Swallowtail, Hickory Hairstreak, Mourning Cloak, Red-spotted Purple, Giant Sulphur, and Orange Sulphur.
White ash is an important source of browse and cover for deer. Its seeds are consumed by wood ducks, northern bobwhites, purple finches, pine grosbeaks, fox squirrels, mice, and many other birds and small mammals. The bark of young trees is occasionally eaten by beavers, porcupines, and rabbits. Because of its tendency to form trunk cavities if its top is broken, mature white ashes are highly valued as nesting sites by cavity nesters such as red-headed and pileated woodpeckers, and then secondary nesters such as wood ducks, owls, nuthatches, and gray squirrels.
The same species also utilize green ashes, and game birds such as wood ducks, grouse, northern bobwhites, and wild turkeys use green ash habitats heavily. Green ash woodlands often shelter the highest numbers of bark-foraging and ground-nesting bird species.
What will all these creatures do for food and shelter when every ash tree in North America is dead? No one can predict the future with certainty, but we can look at what has happened in southeastern Michigan, where this has already happened. Massive gaps in forest cover have favored the invasion of non-native invasive plant species. Japanese honeysuckle, for example, is starting to look like kudzu looks in the Southeast. Soil chemistries are changing, as are water cycling patterns, making it more difficult for remaining native species to maintain themselves. All the dead trees initially favored cavity-nesting birds. So the first few years after the ashes died, woodpeckers and other cavity nesters were more abundant. But the profound disruption in the ash-dominant ecosystems soon led to drastic reductions in the insect species the cavity nesters feed on. No insects means no birds. It’s Rachel Carson’s Silent Spring all over again – only this time the culprit is not DDT, but a non-native invasive insect that cannot be stopped.
What is being done?
Ash species in China – the home of the Emerald Ash Borer – appear to be resistant to this insect. Scientists are trying to figure out how to incorporate that genetic resistance into North American ash species. To that end, they are frantically saving as much ash seed as they can, in the hopes that, someday, they can re-introduce the species with genetic modifications that incorporate Asian resistance to Emerald Ash Borer.
That’s the dream. They aren’t there yet. And no one knows how long all the animals that need ash trees can survive without them. No one knows how ecosystems in which ash trees have been essential components for thousands upon thousands of years will handle such a massive disruption – the extinction of a key ecosystem component.
What can we do?
In the face of the inevitable destruction of all our ash trees, what should we do? Information is always our ally, so stay current on developments regarding the Emerald Ash Borer and any potentially resistant North American ash species. At the end of this post, you’ll find a list of links to get you started.
What am I doing?
As for my Green ash-dominated 1.5-acre floodplain, I’m going to start planting other tree species that I know are adapted to similar growing conditions, starting with the species that are already there, and adding more of some additional species that I have already added that appear to be doing well.
But note, this is a total Hail Mary on my part. The trees I’ll be adding will be young. I’ll be long gone before they can attain canopy height. Thirty-seven canopy-sized (50-70-feet tall) ash trees are way too many trees for me to remove as they die. This means dead ash trees will be dropping pieces of themselves all over the place, most likely including on top of other species growing beneath them.
Additionally, I can’t predict what changes in soil chemistry and water and nutrient cycling will occur. My new additions may not be able to handle these changes.
And the pressure from invasive exotic plant species is already enormous on my property. I spend more time and money on their removal than any other landscaping aspect by far. I may not have the resources to prevent invasive plant species from outcompeting remaining species and my new additions.
But the alternative is to do nothing, to throw up my hands and walk away, and I can’t do that. The green world is what keeps me going – physically, emotionally, and spiritually. I will fight for its survival until I can fight no longer.
You suburban and urban gardeners with no ash trees on your properties may think you’ve dodged a bullet this time, but in fact, you only perhaps have a bit more time to prepare for other battles before us. Already in areas where ash trees are gone, another tree in the same plant family is being attacked: White Fringtree (Chionanthus virginicus).
A new gardening paradigm may be our best hope
Your best weapon will be vibrantly healthy home ecosystems. That is why my proposal for 21st-century gardens across the United States is so critical. Every patch of green will be essential to the survival of native animals and plants. Sterile, chemically controlled fescue lawns won’t help them. Healthy, vibrant, beautiful native landscapes might just save them.
The Emerald Ash Borer is now in the county adjacent to mine. It won’t be long before it finds my beautiful ash-shaded wetland. If you live in the southeastern piedmont in areas with ash trees, I encourage you to take your children, your grandchildren – or any child for that matter – to visit healthy ash trees now. Go appreciate the beauty of their dangling seeds, their compound opposite leaves, their gray furrowed trunks. Lock these images into your memories now, for soon they will be all you have left.
- For North Carolinians living in Orange and Durham counties, on Aug. 20 at 9:00 a.m., the NC Department of Agriculture will hold a public information system on the Emerald Ash Borer quarantine at the Whitted Building in Hillsborough.
- NC Forest Service Web site on the Emerald Ash Borer
- National Emerald Ash Borer Clearinghouse
- Predatory wasps as control for Emerald Ash Borer
- Good photos and information on White Ash in North Carolina
- NC Forest Service list of invasive insects to watch for
- Other dangerous invaders fast approaching:
This is a bumper sticker that a great bunch of students from John A. Holmes High School in Edenton, North Carolina created to help get the message out about a non-native aquatic invasive weed called Hydrilla (Hydrilla verticillata) that is endangering their local river, the Chowan, and many other lakes, ponds, and slow-moving rivers throughout the southeastern US.
These kids and their Earth Science teacher, Stephen Karl, gave an excellent presentation at the joint annual meeting and symposium of the Southeast Exotic Pest Plant Council and the NC Invasive Plant Council that was held at the NC Botanical Garden on May 26-28. I’ll be writing more about the many great presentations I heard over the coming weeks. However, because the topic of non-native invasive species in the southeastern US is not a happy one, I feel obliged to intersperse what I learned with more upbeat posts about my garden.
The objective of this high school project was “to raise awareness by posting videos, posters, brochures, and digital boat ramp signs. ” They are also placing compost barrels at boat ramps along with rakes they’ve re-shaped to fit easily around boat propellers. Their aim is to persuade boaters to rake out the hydrilla from the bottom of their boats when they take them out of the water, and compost the hydrilla in the barrels provided. Hydrilla is mostly spread by boats when they move from contaminated waters to uncontaminated ones.
These are good, relatively simple ideas, and the project made them a finalist in the 2015 Emerging Issues High School Prize for Innovation sponsored by NC State University’s Institute for Emerging Issues. The bumper sticker they printed sports the name they gave themselves: Hydrilla Guerrillas — such a great name!
Theirs was not the smoothest presentation I saw that week. Many of the kids were visibly terrified, even though they had rehearsed their talk. Every student got a chance to speak. At first, they were pretty wooden, standing stiffly at the front of the room, but as they got into their talk, their enthusiasm for the project overpowered their shyness. These kids were passionate about stopping the invader in their home river.
I confess I actually felt hope for the future when these kids started talking about their project. I still am hopeful, mostly, but that hope is tempered by the conclusions of the students themselves. First, they were disheartened to discover that almost no boaters or other local adults they talked to had heard of hydrilla or knew it was a problem.
Second, they’re not confident that their message will have any lasting impact, although I think they certainly tried everything they could think of that was within their budgetary constraints. Third, they’re not convinced that people will change their behaviors. Cleaning boats of hydrilla when they are removed from the water takes time; most folks don’t want to spend that time on something high school kids are telling them about. In fact, the kids expect the special rakes they’ve created to be stolen from the boat ramps. Despite their evident teenage passion, their faith in their ability to change adult behavior is not strong. Frankly, I don’t blame them.
Even so, my take-home feeling for this presentation was one of hope. Mr. Karl, the Earth Science teacher, got his kids energized and focused on a critical problem that will adversely impact their future and the future of their children. I’m hopeful that they will hold on to their enthusiasm and concern as they become adults, so they can teach their children and grandchildren to be better caretakers of Planet Earth than the adults whose behavior they are trying to change.
Do you hate seeing this:
as much as I do? Experts battling these and other non-native invasive plants meet once a year in North Carolina to share information on the most effective eradication and management techniques. They are a good bunch of folks — native-loving plant nerds, if you will — who are passionately working to preserve the health of our dwindling native ecosystems by eliminating/controlling non-native invasive plants.
This year, the North Carolina Invasive Plant Council (NC-IPC) is hosting the annual regional meeting of its parent organization, the Southeast Exotic Pest Plant Council (SE-EPPC) at the North Carolina Botanical Garden in Chapel Hill on May 26-28. Interested citizens are encouraged to attend — no degrees in botany required!
I’m looking forward to a number of presentations, especially including one from Edenton (NC) High School students and their teacher on their study of Hydrilla in their area. This highly invasive non-native plant is rapidly choking our streams, ponds, and lakes to the point of making them unnavigable by boats, and unhealthy for the natives that live in those waters. It lifts my heart to know that young people care about the future of their backyards — and their planet!
Early registration ends this Friday, May 15, so visit this page to register today if you’re interested.
I hope I’ll see you there!
I’ve never paid much attention to Arbor Day until this year. I knew it was a day to celebrate trees and to encourage people to plant them. I knew I routinely get mail from the Arbor Day Foundation offering me “ten free trees” as a reward for becoming a member. And that was all I knew. So I did a little research.
Most states observe Arbor Day on the last Friday in April. Some southern states designate their celebration in January or February — better times to plant trees in the deep South. Some more northern states observe the holiday in late May for the same reason. In the United States, Arbor Day started with an early settler of the Nebraska Territory, J. Sterling Morton. In 1872, when he created Arbor Day, Nebraska’s lands were being transformed from healthy prairies to farmlands. Native prairie ecosystems are relatively dry, soils are rich, and naturally occurring fires maintain the balance of species that comprise healthy prairie.
But when you plow up prairie to create farmland, soil erosion becomes a big problem. Those wide open spaces make it easy for strong winds to pick up huge masses of soil and blow them far away. Hard rains exacerbate erosion. Mr. Morton’s solution was to plant trees around fields to serve as wind breaks. He planted more trees to provide building materials and fuel, and to create shady spots during hot Nebraska summers. Morton grew into a prominent citizen over the years. He persuaded a lot of people to plant a lot of trees. Here’s a fact I didn’t know until yesterday: the Nebraska National Forest — all 141,864 acres of it — was entirely and deliberately planted by citizens of Nebraska. If you ever doubted that humankind can transform the Earth’s ecosystems, look no farther than the Nebraska National Forest — once prairie, now trees.
I spent several hours on the Web site of the Arbor Day Foundation. This nonprofit sponsors a number of great programs. They help cities and college campuses promote and grow trees in their locations, they help people all over the world plant trees to improve their lives, they sponsor nature camps for children who otherwise see very little of the natural world, and they help replant our national forests after forest fires. In these cases, they appear to partner with local experts, for example, the National Forest Service partnered with them to replant fire-devastated forests.
But when the Arbor Day Foundation (ADF) sells trees to US citizens via their Web site, I think they are creating more problems than they are solving. Why? Because from what I saw — and I looked pretty thoroughly — the ADF makes no distinction between native and non-native trees in their offerings. Further, the “Tree Wizard” tool they provide to help folks figure out what kind of tree they should buy is inadequate. And finally, they do not reveal where they get the enormously diverse array of trees — many not native to North America — that they offer for sale. This last bit is important, because the same species grown in a nursery in Wisconsin is much less likely to thrive in South Carolina. Even within a species, genetic diversity exists, and the genes selected for in a Wisconsin-grown tree are almost certainly not optimal for South Carolina growing conditions.
I worked through the Tree Wizard to see what trees it would recommend for my area. After it determines your hardiness zone, it asks what sort of tree you want. Your choices are: evergreen shrubs, flowering trees, ornamental trees, shade trees, evergreens, fruit trees, nut trees, and shrubs. Note that selecting only native plants is not offered as an option. I selected flowering, shade, and nut trees. Under “growing conditions,” the tool gives the following soil type options: all types, acidic, alkaline, drought tolerant, loamy, moist, rich, sandy, silty loam, well drained, wet, wide range, and clay. If you know anything about soil science, you know that not all of those choices are standard soil type options. What the heck is a drought-tolerant soil, for example? You can only pick one type here; I picked loamy. “Sun exposure” choices were all, full sun, partial shade, and full shade. Of course, any gardener with experience knows that in the southeastern US at least, the direction from which the sun exposure comes can be more important than the amount of sun. Some delicate understory native trees prefer morning sun and afternoon shade, for example. I picked full sun. The Tree Wizard next asks you to specify how tall and wide a tree you want, and what rate of growth you want. I picked all heights and all spreads, and all growth rates.
The Tree Wizard displayed 11 pages of results. Its top choices based on my input were: White, Pink, or Red Dogwood, Redbud, Washington Hawthorn, Japanese Flowering Cherry, Kousa Dogwood, Saucer Magnolia, and Southern Magnolia. Most of these are actually native to North America, but the Tree Wizard doesn’t tell you that. Additionally, if you want a dogwood or a redbud to thrive in my region, you should never plant it where it receives full sun all day.
Species names of the tree options are provided, which is interesting in itself. For example, both the Pink and Red Dogwood options are listed as Cornus florida var. rubra. I guess we’re just supposed to trust them regarding which color they send us. They appear to offer only species, no cultivars. For example, the Southern Magnolia they offer is described as likely to mature to between 60-80 feet, which is what the species does in its native environment. Frankly, I am disappointed in the Arbor Day Foundation. Clearly, they do a lot of good things, but when they aren’t partnering with local experts, they appear to blindly follow standard horticulture industry practices for selecting plants. Given the critical issues our native forests face, this is not good enough, especially for an organization that promotes itself as environmentally friendly. As it stands now, this organization — along with most of the horticulture industry in the United States — is actively encouraging plant blindness. They want you to believe that a tree is a tree is a tree. This is dangerously wrong. But the horticulture industry will not change unless its customers demand it from them. This is what I ask all of you who care about the future of our native ecosystems to do when you visit your local nursery, garden department, mail-order nursery, etc.:
- If the plant’s description does not tell you it is native to your region, ask the sellers its origin and why that information is not on the label. If they don’t know, tell them you’re not buying the plant — at least until you’ve had time to research it yourself. I’m not saying you must only buy native plants, but you do need to know an unfamiliar plant’s origins before you consider adding it to your landscape.
- Know which species are considered to be invasive non-natives in your region. When you see them offered in your local nursery (and you will), ask the sellers why they offer plants known to be damaging to the local environment. Tell them you won’t ever buy such plants, and that you’ll be patronizing establishments that don’t sell such plants.
- If sellers cannot tell you more than what the label on the plant says, find another nursery where the staff is more knowledgeable. Unless the horticulture industry loses sales from promoting the notion that plants are interchangeable regardless of origin, they will not change.
- Work with plant sellers who grasp the concept of your yard as an ecosystem. If they can tell you which plants will work together to look beautiful and support native wildlife, patronize their businesses. Your yard is not your living room. Don’t pick plants as you might accessorize a room. Every plant in your yard is a vital, dynamic life form that interacts with every other life form on your property. Make your choices based on how the seasonal dance of life and color will look over time, not on the color of a flower today.
- Stop subscribing to gardening magazines that promote plant blindness and tell them why you’re stopping. “Gardens as rooms” is a decorator’s notion, and not relevant to the construction of vibrant ecosystems that we need to be creating to protect our planet’s future. Beauty can also be healthy, but health cannot be achieved via plant-blind choices.
I am happy to acknowledge that the Arbor Day Foundation is doing much good for the environment. Their failing is the failing of much of the horticulture industry. Its promotion of plant blindness — plants as completely interchangeable entities — must be stopped. Only we gardeners — this industry’s target market — can effect this change by directing our dollars to those businesses that promote awareness of this increasingly critical issue. In my area, I can think of several wonderful locally owned plant nurseries that actively promote native plant gardening and ecosystem-appropriate designs. I can also think of several with inventories full of fancy non-native plants with unknown invasive potential, plants that must be coddled to thrive here, plants that don’t belong here.
When you visit local nurseries, ask the hard questions. If you don’t get the right answers, tell them why you won’t be patronizing their establishments again. If we walk the talk, the horticulture industry will follow. Let’s get moving! Happy Arbor Day, ya’ll. And I promise to write about my gardens for the foreseeable future. 🙂