Posts Tagged invasive exotic plants
I’m reasonably certain that’s a Spring Beauty (Claytonia virginica). This early-blooming spring ephemeral wildflower usually starts blooming just a day or two before the American trout-lilies in a moist woodland at the NC Botanical Garden in Chapel Hill. I’ve always thought them to be exquisitely delicate and lovely, and they were on my “Add Someday” list for our five acres of Piedmont chaos. No longer.
Yesterday, Wonder Spouse and I stumbled across two tiny blooming specimens in the middle of our currently moist floodplain. We haven’t mowed there yet, because we’re still picking up fallen limbs from winter storms, which is probably why it managed to push out flowers in time for us to notice. The Spring Beauties at the NC Botanical Garden grow in what becomes deep shade as the floodplain canopy trees above them leaf out. Our volunteers are in a sunnier locale, near a large pine, perhaps enough to give them afternoon summer shade. From this difference, I conclude that Spring Beauties require moisture more than shade.
Our volunteers likely found their way via floodwaters from our little creek, which is only about ten feet from their growing site, in an area that overflows whenever the creek waters escape their banks. We could not be happier to have this native join us: another native to love.
Wonder Spouse and I spent several hours wandering the floodplain/wetland habitats of our yard yesterday, because this is the time of year when their health is demonstrated by the ecological diversity of the beautiful native plants that thrive in the muck. Indeed, there is much to love in a healthy native wetland. There’s also much to worry about: invaders. Non-native, alien species remain the number two threat to healthy native environments world-wide (after outright destruction), and in my yard, we battle invaders constantly.
From Beauties to Bullies
Some battles are nearly hopeless. Japanese Honeysuckle and Japanese Stiltgrass are so aggressively pervasive in our North Carolina woodlands and backyards that the best most of us can do is to try to keep them out of selected areas — a favorite flowerbed perhaps, or a beloved tree, in the case of Japanese Honeysuckle.
Battles Still Worth Fighting
In my wetland/floodplain areas, the invader we are still fighting — so far, successfully <knock wood> is Chinese privet. This evergreen, common hedge shrub of older homes produces blue-purple berries that birds adore. They distribute seeds everywhere, but the privets are most dangerous to floodplain/wetland environments. In some areas in eastern North Carolina, the understory composition of vast acres of wetlands has been completely overtaken by invading privet. Because these non-natives are evergreen, they outcompete wildflowers, shrubs, and tree seedlings for light and other resources. Eastern North Carolina wetlands are becoming biological deserts, consisting of nothing but privet beneath canopy trees. When those trees die, no seedling trees will replace them, because they can’t compete successfully with privet. Eventually, our eastern wetland landscape will consist of miles and miles of nothing but privet.
Plant invaders are overlooked by most folks, because their progress is slower than, say, invading Emerald Ash Borers or Sudden Oak Death. To the untrained eye, green is green. But native animals and plants know how critical the differences are. If you love your southeastern Piedmont landscape, you should know too.
Whenever Wonder Spouse and I walk around our yard, we keep a sharp eye out for Chinese privets (Ligustrum sinense). Seedlings appear constantly, typically beneath trees, where birds deposit the seeds after feasting on privet fruits elsewhere. Yesterday, we spotted several larger shrubs that we had somehow overlooked previously. Greens blend together, and in crowded thicket areas (left for animal nesting habitat), a privet sometimes escapes our notice — for a while. I am especially vigilant in my hunt for this species in my wetland and along the edges of my creek. These areas are most vulnerable to this devastating invader.
While hunting privet yesterday, I was disturbed to discover that some of the Autumn Olives (Elaeagnus umbellata) invading the top of our hill have made it to the floodplain and wetlands. This pernicious invader has taken over many acres of upland environments, such as ridge tops, in my part of the southeastern Piedmont. This species and its close cousins (E. angustifolia and E. pungens) are all non-native shrub species. All are very bad news for the local environment, despite the berries that birds eat with gusto.
Wonder Spouse grabbed his trusty Weed Wrench and went to work on the invading Elaeagnus shrubs, pulling out long-rooted invaders from mucky ground, accompanied by a rather satisfying sucking sound.
Note the flowers just opening on this one:
This was a larger one that put up considerable resistance before Wonder Spouse prevailed:
A New Enemy
And, there’s more bad news for my little patch of Piedmont: Asiatic Hawksbeard (Youngia japonica). This relatively recent annual invader was introduced by the nursery trade. It was probably inevitable, given the number of plants from nurseries that I’ve added over the decades, that this horrifyingly aggressive invader would appear on our property.
To the casual eye, the basal rosette of jagged leaves of Youngia looks quite like that of a Dandelion. But if you look a little more closely, the dangerous differences become evident. It sends up clusters of small yellow flowers on bloom stalks. Dandelions only produce one, much larger yellow flower per stalk. Seeds of Asiatic Hawksbeard look somewhat like those of a Dandelion; they are both attached to white tufts that allow them to float far on breezes. But Hawskbeard seed tufts, like its flowers, are much smaller — and uglier — than those of Dandelions.
I know you’re thinking this is just one more lawn weed, right? Not really. Unlike our common non-native weeds — Dandelion, Henbit, Chickweed, Lambs Quarters — Asiatic Hawksbeard spreads much, much more aggressively. Its basal rosettes are dangerously easy to overlook, and now the experts tell me that they are moving into our dwindling natural areas. In these diminishing patches of native forest, Asiastic Hawksbeard is joining Japanese Stiltgrass, Japanese Honeysuckle, and larger invaders in displacing native wildflowers and other small native plants. Every new invading plant means more competition for food, light, and water for our natives. With no natural predators to slow them down here, their eventual takeover seems a near certainty.
Asiatic Hawksbeard has a taproot similar to that of a Dandelion, and if you don’t get it all when you pull it, the plant will regenerate. Also, you can’t just toss pulled Hawksbeards onto your compost pile. Flowers and even nearly-open flower buds finish their cycle and release seeds into the environment even after they’re pulled. Knowing this, I spent many, many hours last year carefully digging out this new invader from my yard wherever I found it. Every plant went immediately into a trash bag, which I tied and left in the hot sun to fry before adding it to my trash can. Despite my efforts, the Youngia is much more pervasive now that it was last year. And I’m seeing it in all parts of my yard now, whereas, last year, it was confined to only certain areas. The basal rosettes have a distinctive yellow cast, and the leaves are slightly fuzzy. I’ve become quite adept at spotting them. Next winter, whenever we spot one, Wonder Spouse and I are planning to resort to treating them with Round-up. Wonder Spouse and I are ridiculously outnumbered, and this is a war we don’t want to lose.
Reasons to Keep Fighting
And there is so very much to lose. On this Earth Day, let me leave you with a few positive images from our still-healthy wetland, where the wildflowers and other plants are wakening to warming weather with enthusiasm for another growing season.
On this Earth Day — and every day — I will continue to love the diverse and beautiful native species that bless my property. And I will battle non-native invaders as long as I can breathe. Clean water and air can’t exist without the help of healthy native environments — especially wetlands. Do your part today and every day by eradicating invaders in your yard. To learn more about invaders in Southeastern North America, start here.
It doesn’t look particularly imposing in this picture, but that’s a mountain in the background. I discovered I had no great photos of the majestic Great Smoky Mountains when Wonder Spouse and I returned from our recent vacation in far western North Carolina. All my good shots are of flowers and/or pollinators. Go figure.
Wonder Spouse and I made the trek to higher elevations to celebrate the passage of his recent milestone birthday. For the sake of marital harmony, I shall refrain from identifying the milestone to which I refer. Happy Birthday again, sir!
We enjoyed ourselves immensely, and we met many wonderful folks as we traveled about. However, I found myself often dismayed by what has happened to much of the landscape. From a distance, the mountains are still as beautiful as I remember from childhood visits. On the ground, the story was much different. Almost every single road we traveled was edged by rampant kudzu (Pueraria montana var. lobata) overgrowth. The vines scaled towering rock cuts through mountains, smothering trees, rocks, and shrubs as far back from the road as I could see.
Even in the Nantahala National Forest, kudzu was often the only green plant I could see as we drove along. This was especially horrifying to me as we drove through the Nantahala River Gorge. On the day we were there, the Nantahala River was crowded with kayakers and rafters enjoying the journey downstream through rocky rapids. Perhaps they were too busy dodging boulders to notice that either side of the river was overrun by kudzu — an invasive exotic species originally introduced to the US in the 1930s to control erosion.
The only light moment for me during that drive was a road sign that read “Watch for slow raft buses next ten miles.” Until I saw the old school buses with platforms built on their roofs that held stacks of colorful inflatable rafts, I was mystified.
Invasive exotic plants were mercifully much less evident during our pilgrimage to the Joyce Kilmer Memorial Forest. This preserve protects a forest with 400-year-old trees. Until you’ve stood beneath Tulip Poplars with circumferences more than 20 feet, you cannot begin to imagine what our southeastern forests must have once been like.
Even in early autumn, evidence of mountain wildflowers was everywhere. Tall white plumes of Black Cohosh were still abundant. Stream slopes were adorned with leaves of all the spring wildflowers. They must be quite a sight in April. Deciduous magnolias dotted the hills, along with Cinnamon-bark Clethra. It was quite wonderful to see these native trees where they belong; I hope they eventually look as lovely in my Piedmont landscape where I’ve planted them.
Yellow Jewelweed (Impatiens pallida) was blooming prolifically. I’m not sure I convinced a visitor we met on the trail that this gorgeous yellow wildflower was not an orchid. I tried to explain to him that the orchids native to this habitat don’t bloom this time of year, but I’m not sure he was persuaded.
This wildflower was also abundant at the school where we spent most of our time in the mountains. While Wonder Spouse honed his photography skills, I wandered the large property, where I constantly encountered a depressing number of invasive exotic plant species. This vine was growing on a trail we walked daily to reach the dining hall.
Oriental Bittersweet (Celastrus orbiculatus) was imported as an ornamental for home landscapes. As happens so often, it has escaped into our woodlands. This particular invasive vine is bad in spots in the Piedmont, but not on my property. I hadn’t realized how common an issue it has become in our mountains until I saw it growing here.
During my walks along the grounds of the school we were visiting, I saw many other invasive exotic species throughout the property, including mulitflora rose, privet, Japanese bamboo grass, Princess Tree, Tree of Heaven, and English ivy. All had clearly escaped from former home landscapes. Many of these plants produce fruits beloved by birds, which is how these invaders have spread so insidiously. Others make seeds that are lightweight and travel far via air and water.
The best Web site I know of to learn more about invasive exotic plant species in the mountains of North Carolina is part of the site for the North Carolina Exotic Pest Plants Council. To learn about the mountain invaders and how to control them, go here.
The size and seeming solidity of mountains make it easy to imagine that theirs is an unchanging landscape, where time stands still, or at least moves too slowly for mere humans to notice. My recent visit to the Great Smoky Mountains has dispelled that illusion. The hand of humankind is all too evident. I can’t help wondering how much longer the exquisite ecosystems native to this region can hold out.
Faithful readers of this blog may recall that last month I wrote an entry in which I tried to answer some of the questions from search engines that lead people most frequently to my blog. For example, frequent searches still find my blog while seeking information on tomato ‘Indigo Rose’ and how to tend your garden during record drought and heat waves. Lately, a few other topics have been recurring regularly, so I thought I’d directly address some of them for you today.
First, check out the top photo. We finally got some decent rain last weekend (2.5 magnificent inches), and that moisture rekindled enthusiasm among my vegetables. All but one of my squash plants surrendered to the heat and bugs several weeks ago. But one zucchini ‘Spineless Perfection’ continues to survive and produce fruit against all odds. A close examination of the stem shows clear evidence of Squash Vine Borer intrusion, but this plant has outwitted the bugs by taking advantage of the fresh mulch that Wonder Spouse and I applied to all the paths between the veggie beds. This plant flopped itself over one side of its bed and into the path, and everywhere its stem touches the mulch, it sprouted new roots. Eventually, the borers will overcome this defense, but for now, I’m still picking a few zucchinis every week. I will definitely be growing this variety of zucchini again.
When tomatoes receive a lot of moisture in a short time, sometimes the fruits will split, because they try to expand faster than the skins can stretch. I’m happy to report that the 60 seconds of water my tomatoes were getting every third day during the heat wave/drought, combined with the deep mulch in the paths, prevented my tomatoes from exploding from the recent surge in moisture. As you can see from the photo, all varieties are producing well, and the Carmen and Merlot peppers are also cranking bigtime. Yes, I am cooking down tomatoes into sauce for freezing on a regular basis so as not to waste a single red globe of goodness.
Now, on to a couple of questions.
Princess Tree (Paulownia tomentosa)
In the last month, several searches have found my site searching for a “tree with heart-shaped leaves and seed pods.” Sometimes the search says “giant heart-shaped leaves,” which is why I’m fairly certain these searchers are wondering about Princess Trees.
This non-native, highly invasive tree plagues 25 eastern states in the US. It was introduced deliberately as an ornamental tree, and some lumber companies are now actually growing plantations of these invaders for their lumber, which the Japanese adore. In the spring just as invasive Chinese Wisteria is finishing its blooming period in my area, these trees produce large upright clusters of purple flowers that resemble wisteria flowers from a distance. I suppose some might call the flowers pretty; I call them trouble.
The problem lies with the papery seeds that lurk within the abundant clusters of seed capsules. Experts have determined that one tree produces 20 MILLION seeds in one year. These light-weight seeds float far on wind and water, invading disturbed areas like roadsides and newly logged land. These trees can grow 15 feet in one year, and after they are established, it takes serious perseverance to eradicate them. It can be done. The link above offers instructions and more information on this aggressive invader.
Purple Coneflower (Echinacea purpurea)
Some folks want to know what’s eating the petals of these lovely, tough native wildflowers. The short answer is that any number of bugs may be nibbling on your flowers. In my gardens, where this wildflower thrives on my total neglect, petals do get nibbled. But I have so many that you don’t notice unless you get right on top of them. And I’ve never had a case in which all the petals were devoured. I can always find a plant or two worthy of a photograph.
I’ve also seen questions about whether these flowers multiply, and if they do so every year. In my sandy loam garden soil, my coneflowers multiply vegetatively at least a little every year. From the base of the mother plant, new plants sprout from her roots. When these new plants have a few leaves — usually in late fall — I gently separate them from the mother plant and plant them elsewhere. If I don’t get around to doing this, the baby plants usually manage to grow and flower right where they were born.
Because the central “cones” of the flowers are so showy even in the winter landscape, I don’t cut them off when the flowers fade. I also leave them because the seeds of this native are deemed desirable by goldfinches and several other seed-eating birds. I let the birds devour as much as they want. Inevitably, they scatter some seeds on the ground, at least a few of which sprout to become new plants the following spring. Sometimes, an entire seed head is overlooked by the feathered ones. I can always tell when this happens, because I’ll get a zillion tiny coneflower seedlings sprouting in one spot the next spring. I separate them and transplant them to ensure a continuing supply of these beauties.
Recently, someone found my entry on coneflowers while searching on “my purple coneflower grew a white flower.” Yes, it probably did. In fact named cultivars of white-blooming purple coneflower are sold commercially. ‘White Swan’ is a commonly sold cultivar of this species. If you bought what you thought was a purple-blooming plant from a nursery and it produced white flowers, your seller was careless during propagation. Named cultivars of plants are mostly propagated vegetatively, meaning they grow cuttings from a known desirable plant, or remove offsets from mother plants, as I described above.
But if you grew your coneflowers from seeds, it is entirely possible that one or more of them would produce white flowers. White flowers are a recessive color trait in this species, meaning that two purple coneflowers can produce a white coneflower baby if both carry this recessive color gene, much as two brown-eyed people can produce a blue-eyed child, if both parents carry the recessive gene for blue eyes.
In my gardens, white coneflowers pop up regularly in small numbers, because I do allow the seed heads to complete their life cycles where the plants grow. Personally, I think the white coneflowers contrast nicely with their dominantly purple siblings, adding a little variation to the landscape. I took the following photo of my front garden last year. As you can see, a recessive white-blooming flower grows with its more common purple siblings.
If you bought a named purple-blooming cultivar of purple coneflower from a nursery, you have a right to complain, but if you’ve been letting your coneflowers reproduce on their own, consider the white one a happy addition — a blue-eyed child in a brown-eyed family, if you will.
More answers to your searches in future entries.
Happy gardening to all.
I call the bloom period of the invasive exotic Chinese Wisteria (Wisteria sinensis) the Purple Plague, because the long, grape-like clusters of blooms are purple, and because the bloom period of this invader visually emphasizes its plague-like effect on our southeastern US woodlands.
I’ll concede that the blooms are not ugly, and many folks like their overpoweringly sweet fragrance, although I’m not a fan. It was the aesthetic appeal of this plant that got it here. Many southerners fell in love with it, draping it over arbors, sides of houses, and training it into artfully shaped waterfall-like forms in their front yards.
If Chinese Wisteria stayed where it was planted, I would not object to its existence in southeastern yards and gardens. But it doesn’t, not by a long shot. Actually, shot is a good word here. You see, the seed pods of this vine are long, bean-like structures. On late autumn days when atmospheric conditions are just right, the pods split open with a resounding crack that sends seeds flying explosively in all directions. I’m told by folks who live near heavily invaded forests that when the pods explode, it sounds like rapid gunfire that goes on and on and on, until all the pods have expended their loads.
Why is this vine considered to be a problem? Take a look at this tangled mess growing along a major road about 5 miles from my house:
Like the evil invader Japanese Honeysuckle (Lonicera japonica), vines of Chinese Wisteria climb over every plant in the forest, creating impenetrable tangles of vegetation that destroy any chance for a healthy ecosystem in such areas.
Chinese Wisteria vines can grow quite large and woody. The extra biomass, especially when vines are leafed out in summer, can add enough weight to burdened trees to make them much more likely to fall or break during wind events created by thunderstorms and hurricanes. During winter ice storms, when one burdened tree falls, those connected to it by this invasive vine are also likely to fall, pulled down by the vines tangling them together.
As with Japanese Honeysuckle, the sprawling masses of tangled vines, trees, and shrubs, create perfect highways for predators like black snakes, raccoons, and other climbers. In such areas, it is vastly easier for these predators to access and devour eggs and nestlings of many of our native songbirds.
In my opinion, there is never a good reason to deliberately introduce invasive Chinese Wisteria into a landscape. It will not — not ever — remain only where you plant it. It will — without question — escape into nearby woodlands, where it will destroy the integrity, beauty, and health of these small forests that are essential to native wildlife and plants.
And there’s a native alternative to this invader: American Wisteria (Wisteria frutescens). It is not as flamboyantly showy as the Chinese invader, but it performs the same functions — covering arbors, for example, just as beautifully with similar flower clusters. Most importantly, our native Wisteria vine does not escape and destroy our forests — reason enough to plant it instead, if you ask me.
I will freely admit that Chinese Wisteria is not the most damaging invasive exotic plant species in my region of the country. But it’s blooming and very visible right now, so I think it serves as perfect symbol for North Carolina’s second annual observance of Invasive Species Awareness Week, which runs from April 1-7 this year. Many conservation-related organizations plan activities during this week that highlight this issue. The site links you to a calendar of events occurring throughout the state this week.
Many botanists and ecologists believe that invasive species represent one of the top two threats to our native ecosystems. The other threat is habitat destruction due to land clearing. These two issues are related. As more land is cleared, smaller tracts of native forest remain. These smaller tracts are much more easily overtaken and destroyed by exotic invasive species.
If you live and garden in North Carolina, I ask that you take a few moments to visit this link to the Web site of the North Carolina Exotic Pest Plant Council to learn more about invasive species in our state.
If you live in a different state in the southeastern United States, visit this link to the Southeast Exotic Pest Plant Council. The home page includes links to all the member state organizations, so you can find out what they’re doing about invaders in your state.
As a life-long gardener in the Piedmont region of North Carolina, I can personally attest to the transformation of my native woodlands by invasive exotic plants. When I was child roaming Piedmont woodlands in the 1960s, Japanese Honeysuckle was not strangling the trees. Autumn Olive (Elaeagnus umbellata) and Japanese Stiltgrass didn’t overwhelm my beautiful woodlands until a decade or two ago. Same for Chinese Privet (Ligustrum sinense). The invaders are coming faster now and establishing themselves much more quickly.
Anyone who cares about the long-term health of our native ecosystems should be deeply worried. I know I am. Please educate yourself about these invaders, learn about the many lovely native plant alternatives to the dangerous species.
Much good information is out there. Besides the Southeast Exotic Pest Plant Council site, try the information-packed Web site of the North Carolina Botanical Garden. Here’s a link to their list of exotic invasive plants to avoid. And here’s a link to the page where they offer suggestions for native plant alternatives.
With just a bit of effort, your garden and yard can become part of the solution to this growing problem. Please consider joining me in this battle against alien invaders. Together we can fight the Purple Plague, and restore a healthy balance to our native landscapes.
If you live in the Southeastern United States, you know this shrub even if you don’t think you do. When I was a child in the 1960s, it was the go-to landscaping choice for quick, easy hedges — evergreen, amenable to severe trimming, and impervious to predators and diseases.
Some people claim to enjoy the fragrance of the white clusters of flowers. Frankly, I’ve always thought they stink — and they make me sneeze like I’ve inhaled a snootful of pepper. I hated them even before I knew what they do to our native forests.
Those white clusters of flowers produce big clusters of purple fruits that birds find irresistible. The berries are this invader’s secret weapon. The birds unwittingly spread Ligustrum seeds everywhere, and this shade-tolerant non-native species quickly grows to enormous size, multiplying its numbers as it outcompetes our native forest understory species.
How bad is the problem? Chinese Privet (Ligustrum sinense) is especially aggressive in our wetlands. A wooded creek near a shopping mall I pass often is completely overgrown with Chinese Privet. In winter, the evergreen invaders are especially visible. They outcompete native wildflowers, ferns, and smaller shrubs and trees for light and nutrients, because their evergreen leaves are working year-round. The natives never see the light of day after these bullies move in.
In North Carolina’s Coastal Plain region, many thousands of acres of swamp forest are now dominated by an understory of privet. Biologists note the quantum drop in species diversity — plant and animal — in areas where Ligustrum rules — a biological desert compared to the days before this invader took over. Nothing eats the leaves, and few natives plants can survive where it dominates.
Because my yard is adjacent to a creek and wetlands, I am constantly on the lookout for this invader. I am determined that my wetland will not look like the one near the shopping mall a few miles from my house. Winter is the best time to spot them in the landscape. When a glint of shiny green catches my eye in February, I know it’s either a holly or a privet.
I can pull small privets out of the ground roots and all in moist soil. Bigger specimens (yes, they occasionally manage to hide from me on my five acres) require Wonder Spouse and his mighty Weed Wrench. Don’t even think about cutting them off at the ground; they come right back, sprouting into even bushier specimens than the originals.
I hate them because of what they are doing to the health and biodiversity of my native woodlands. I hate them because they smell bad. I hate them because they are ugly. I hate them!
Plant nurseries still sell privets today. A fancy variegated form is often touted as an elegant landscape addition. Don’t be fooled. There is no such thing as a noninvasive privet. None is native to North America. Infinitely better native hedge shrub options are available. So, please, just say no to Ligustrum, and do your best to eradicate any loitering invaders in your yard.
For more information on this malicious invader, try here.
And if you live anywhere near the North Carolina Botanical Garden in Chapel Hill, NC, you’ll want to stop by beginning on February 25 to see:
“Plant This, Not That—Alternatives to Invasives,” an educational exhibit at the North Carolina Botanical Garden, opens on Saturday, February 25. The public is invited to attend an opening celebration in the gardens’ Education Center at 1 pm. Associate Director for Natural Areas and Conservation Programs Dr. Johnny Randall opens the event with a short program about invasive plants. The presentation will be followed by a reception, during which six artists who created the exhibit will be on hand to discuss their work. The event is free, though an RSVP is encouraged: call 919-962-0522.
“Plant This, Not That” consists of a series of panels discussing invasive plant issues and showing examples of ornamental native plants that can be used instead of invasives in gardens and landscapes. The artists who created the accompanying illustrations are graduates of the Botanical Garden’s Certificate in Botanical Illustration Program: Irena Brubacker, Betsy Lowry Donovan, Glenda Parker Jones, Joanne Phillips Lott, Julia Shields and M.P. Wilson. Their original paintings will be on display during the reception.
The event launches National Invasive Species Awareness Week, February 26 – March 3, the purpose of which is to bring attention to the impacts, prevention, and management of invasive species and to organizations who are working toward healthy, biodiverse ecosystems.
The North Carolina Botanical Garden is located off Fordham Boulevard at Old Mason Farm Road in Chapel Hill. A unit of The University of North Carolina, it has been a leader in native plant conservation and education in the southeastern United States for more than 40 years. The Botanical Garden is open 7 days a week and admission is free.
Minor News Flash:
On the right side of my blog page, you’ll see a new addition — an image that links to the Nature Blog Network. I’m proud to say my blog is now a member of this group, where you will find fascinating nature-related blogs from writers all over the world. Click on the link and check out this site; I think you’ll like what you find.
What’s the old saying? Insanity is repeating the same act over and over and expecting different results? Or is that stupidity? Either way, on my five acres of North Carolina Piedmont, my greatest exercise in futility is probably attempting to remove/control Japanese Stiltgrass (Microstegium vimineum). Oh, how I despise this invasive exotic plant species. Let me count the ways.
1. It is ugly and covers everything. As you can see from the above photo, it grows tall and droops over everything, living and inanimate. Even when this annual grass dies with the frost, its straw-like dead remnants bury my landscape in destructive brown yuck. That’s a little pond that fluctuates with the level of the perched water table on my floodplain. I’ve surrounded it with myriad well-adapted wildflowers and native shrubs. But you’d never know it by that photo. It’s one of the areas that I didn’t weed this year. Now my pond environment pays the price.
2. It creates rodent habitat that thwarts predators. As these evil invaders create grassy hummocks over logs, shrubs, and small trees, they create excellent cover for field rats, deer mice, and voles. It’s a tunnel-filled grass metropolis in there. You’d think a rodent population boom would benefit my native predators, especially the Barred Owls and Red-Shouldered Hawks. Alas, no. The grass is so thick and covers so much territory that the rodents can largely conduct their business without ever coming into the open and risking capture.
3. It destroys/alters native plant communities. That’s the edge of my property on the floodplain in the above photo. The green area is where we stop mowing (we mow to reduce tick and snake issues). The hummocks of straw-like material are mounds of Japanese Stiltgrass, which are growing on an area that we used to mow before we figured out it wasn’t technically our land. Behind the Stiltgrass, you can see native floodplain vegetation still trying to fight the onslaught of the invader. It was there undisturbed before the Microstegium took hold. If our floods ever return, that vegetation will likely be overwhelmed.
That’s how the Microstegium got to our property — via floodwaters. Back in the pre-drought decades (how I miss them), our creek usually flooded spectacularly 5-8 times a year. As more and more developments sprouted up nearby, removing forest cover, Japanese Stiltgrass appeared in those developments (probably from seeds off bulldozers and other heavy equipment). This annual produces a lot of seeds, and one of their favorite modes of transport is water. Rainwater runoff carried seeds from those developments into my creek, where floods deposited them on my floodplain.
4. It has killed almost all the wildflowers and ferns that grew along my creek 15 years ago. As you can see in the above photo, the nasty stuff overwhelms everything. Delicate ferns and wildflowers don’t stand a chance.
5. Every object I introduce into my garden is a potential Microstegium support, even though that is never my intention. In the above photo, Japanese Stiltgrass climbs the deer fencing on my north side. I can’t mow right up against the fence because of the way it’s installed. Weedeaters don’t work there either. Hand-pulling is the only option. That’s back-breaking, knee-creaking work. And if you don’t do it before the grass sets seed in mid-summer, what you pull returns a hundred-fold anyway. Did I mention something about an exercise in futility?
6. It wastes enormous amounts of time that Wonder Spouse and I could be using for other things. That mountain is the result of last week’s clean-up of our deer-fence-enclosed north side. It’s about eight feet high and twelve feet wide, and is a mix of fallen branches, leaves, and Japanese Stiltgrass. In areas of our yard where the grass hasn’t invaded, we rake up the leaves, shred them, and use them for vegetable garden mulch. But the leaves in that pile were too heavily tangled with the Stiltgrass to recover. A close-up of the pile demonstrates the problem:
If there’s any good news there, it’s that Mount Brushmore is excellent winter habitat for a variety of birds, racoons, and possums. Air pockets created by piled branches are covered by the thick mass of grass and leaves, creating a thatched roof of sorts that repels rain and insulates against cold.
7-1000. Multiply the above reasons by the number of seeds one plant produces in a season. That’s right. One plant can produce up to 1000 seeds. Contemplating the math is not advised for gardeners with high blood pressure.
When I roamed North Carolina Piedmont woodlands and stream sides as a child and young adult, Japanese Stiltgrass was nowhere to be seen. This invader has transformed/destroyed Piedmont wetlands in just a few short decades.
The deer won’t eat it under any circumstances, but they do enjoy sleeping among the hummocks in winter — instant straw mattresses. I wouldn’t dream of trying to control it with herbicides — not on a wetland, and not with struggling native grasses still present.
One faint hope may be appearing. In Virginia, a fungus has been found to be infecting colonies of Microstegium. The grass seems to be severely impacted by this fungus, and scientists are studying it to determine its origin and whether it can be safely introduced elsewhere to control infestations of Microstegium. All my fingers and toes are crossed on that one. I’ll keep you posted.
Meanwhile, I’ll continue to spend my winters raking dead Japanese Stiltgrass off of plants and structures in the hopes that next growing season I’ll be able to pull the nasty stuff before it sets seed. Oh, did I mention that seeds remain viable in the soil for many years? Yes, sometimes I do wonder why I try to garden at all.
I told you about it here, but I wanted to remind everyone in North Carolina that the week of April 4-10, 2011 has been declared by the Governor of NC to be Invasives Awareness Week. The issue of invasive exotic species is an increasingly serious one throughout the United States, even the world.
And it most certainly is serious in the southeastern United States, especially in the Piedmont region, because so much land is being disturbed as millions of new folks continue to relocate here.
If you live in North Carolina, the North Carolina Exotic Pest Plant Council has set up a Web site about Invasives Awareness Week that lists all the groups across the state holding events to bring attention to this issue during the upcoming weeks. Find an event near you and go learn what you can do to help.
If you live in the southeastern US and you are interested in the health of the fields and forests that surround your homes and communities, I encourage you to educate yourself about this issue. Learn which space invaders are our biggest threats. Learn how to identify and eradicate them from your yards and gardens. The more of us who know about this issue and are willing to do something about it, the more we can all hope our native environments will withstand this exponentially increasing assault on them. A good place to start is the Web site of the Southeast Exotic Pest Plant Council.
And if you’re wondering what invasive species have to do with piedmont gardening, I assure you the two subjects are intimately linked. Gardeners are contributing significantly to the problem by continuing to buy and plant invasive exotic species in their yards and gardens, and to tolerate those already growing there.
But even if your yard is free of invasive species now, it won’t be for long if we don’t take steps to protect surrounding woods and fields from further contamination by non-native space invaders. If our fields and forests continue to be degraded by invaders, much of what we love about the southeast Piedmont will begin to disappear. The first to go will be sensitive wildlife species as their food sources and habitats disappear.
I, for one, don’t want to live in a Piedmont without the summer song of Wood Thrushes in the shrubby shadows, or the caterpillar-devouring help of the myriad warblers that visit during the growing season.
The southeastern Piedmont is a beautiful place. That’s why so many people from other parts of the country and the world continue to move here. I pray that all of us — newcomers and native Piedmonters — will become increasingly wise stewards of these special lands.
Throughout the world, and most definitely in the southeast piedmont of the United States, invasive exotic species are negatively impacting native ecosystems. Many of these invaders create financial hardships on people trying to navigate invasive-clogged waterways, or grow timber for harvest in invasive-choked woodlands. As I mentioned in an earlier entry here, invasive exotic species may be bacteria, viruses, fungi, fish, insects, animals, and plants.
In the southeast piedmont region of North Carolina where I live and garden, I’ve noticed exponential growth of exotic invasive plant species in my yard and adjacent woods. Here’s a typical example of what Japanese honeysuckle (Lonicera japonica) is doing to our woodlands:
The leaves of the vines outcompete tree leaves for light, and the vines themselves often girdle trunks, especially those of smaller trees (like the ones completely covered in the photo above). The additional weight of the vines makes afflicted trees more susceptible to breakage from ice and wind storms.
And, to top it all off, the vines make it much easier for predators, such as black snakes, to reach nesting birds in the treetops. Climbing a thick mass of sprawling vines is far easier than scaling a tree trunk, so snakes can go higher, and devour more eggs and nestlings.
This year, the North Carolina Exotic Pest Plant Council asked the Governor of North Carolina to declare the week of April 4-10, 2011 as North Carolina Invasive Species Awareness Week. The NC-EPPC is a state-wide group trying to bring attention to the negative impacts of invasive exotic plant species by encouraging conservation organizations, state parks, etc. to hold events that week that highlight this issue.
If you live in North Carolina, check with your local conservation organizations, state parks, aquariums, etc. for activities planned for NC Invasive Species Awareness Week. I know, for example, that the Triangle Land Conservancy is planning to feature some activities related to invasives during that week. For North Carolinians, this week will offer opportunities to learn how to identify and control invasive exotic plants in your backyards. Japanese honeysuckle is just one of many invaders you need to watch for.
I’ll continue to write about this significant threat to our native ecosystems from time to time. This is a battle we should all be fighting. We can’t allow the space invaders to win.
Forty-five or so years ago when I roamed the young forests of Alamance County, North Carolina near my home, I never saw Japanese honeysuckle strangling trees. Floodplains and creek banks were covered in moss and wildflowers. Japanese stiltgrass and privet shrubs were nowhere to be found in such places.
The piedmont hills I explored had probably been agricultural fields thirty or forty years earlier. After they were abandoned, healthy piedmont forest began returning as it always had — as it still tries to do today when cleared land is left empty.
But thanks to intentional and accidental human assistance and the efficiency of modern transportation systems, alien species — plants, animals, fungi, and viruses — are moving into areas far from where they evolved. Beyond the reach of the checks and balances of their natal ecosystems, many of these non-native species are rapidly disrupting the native ecosystems they invade. The problem is world-wide and growing exponentially, and it is an issue I believe every piedmont gardener should be aware of.
When I speak to garden clubs about this issue, I am always asked why it’s a problem So what if new species move in — hasn’t that always happened? Isn’t that evolution in action? No, this is not the same for many reasons.
For one, the time scales aren’t the same. Evolution is usually a very slow process, which provides all the components of an ecosystem with time to adapt to changes. But modern transportation and human actions have accelerated the time scale at rates never before encountered by species attempting to adapt to changes in their environment.
And for those of us who love native forests, grasslands, and all our other native ecosystems, invasive non-native species are actively transforming some native environments into biological deserts, where the invading species dominate at the expense of most of the previous inhabitants. We are losing the rich diversity of our native fields and forests that support our wildlife — and us.
At the forefront of this battle to repel alien invaders are the people who manage and protect our national and state parks and other lands designated as worth preserving for their historic importance and/or extraordinary beauty and, often, rare species. Every time gardeners add known alien invasive plants to their landscapes, they are increasing the likelihood that these plants will escape into adjacent natural areas, and eventually, to our special places — our parks and preserves — national treasuries of our nation’s biological assets.
What can piedmont gardeners do? You can identify and eradicate known invasive species from your landscape. And when you go to nurseries and garden centers to buy new plants, always ask if the plant is known to be invasive. If the store clerks don’t know the answer, don’t buy the plant until you’ve researched its invasive potential yourself. And if it is potentially invasive, don’t buy it.
Many non-invasive options exist for your garden. Many on-line resources are available to help you learn more about this subject. And I guarantee you that, wherever you live, nearby conservation organizations are actively dealing with this issue and could use your help. Here are a few links to get you started.