Showing posts with label Invasive Plants. Show all posts
Showing posts with label Invasive Plants. Show all posts

Sunday, September 17, 2023

Last Chance to Pull Stiltgrass

This week and maybe next are your last chance this year to pull stiltgrass (Microstegium vimineum). This mega-invasive is an annual, so the logic of countering its spread is to pull it before it can produce and drop seed. If the seeds haven't loosened yet at the end of the stalk, you can still pull it. Throw it in the trash, or if there's a lot, make a big pile of it so that any seeds that sprout the next year will all be in one place and easily covered or pulled. Definitely don't put it in your compost if its seeds are forming. If stiltgrass is just starting to invade your yard, pulling as completely as possible now will greatly limit its seedbank for next spring. Another strategy for large stands is to let the stiltgrass grow, then just as it begins to flower mow it short and hope its feeble roots don't have enough energy to grow another flowering stalk. 

For those fuzzy on identification, google lots of images, and look for the silver line running down the middle of the leaf. Stiltgrass can grow in the shade or sun, climb up to four feet, or thrive in a miniature state while ducking below your mower in the lawn. It's incredible survival skills include being incredibly inedible for wildlife. Stiltgrass gives nothing back to the habitats it increasingly dominates.

More on Stiltgrass, and a Success Story

Walking in the local woods, you've probably seen this kind of scene--what looks like a grassy meadow extending through the forest. In the filtered light of the understory, its simplicity and lushness may have some visual appeal. And yet, in some ways what you are looking at is the ecological equivalent of an urban food desert. 

Stiltgrass is an introduced plant that could be called a pervasive invasive, able to thrive most anywhere and dominate whole landscapes. Its success has come in part through being inedible. As wildlife selectively eat native vegetation, the stiltgrass expands, preventing the native plants from rebounding.

Unlike another nonnative annual weed that can look similar, crabgrass, stiltgrass becomes ubiquitous because it can thrive in sun or shade. That means the stiltgrass invading your lawn and flower beds can continue spreading ad nauseum into the nearby forest, or vice versa.

We used to call it bamboo grass--something in the shape of the leaves is reminiscent. The stiltgrass name refers to its angular growth, with each segment supporting the next as it climbs up and over fallen logs and other plants. Packing grass is another common name, referring to how it was once used to pack porcelain for shipment. That's probably how it first reached the U.S., in packing crates sent to Tennessee. 

When I first encountered it, growing on the bank of Ellerbe Creek in Durham, NC, I thought it graceful. Then came Hurricane Fran, bringing floods and fallen trees. In the aftermath of that massive disturbance, stiltgrass exploded in the landscape, expanding and ultimately choking forests with its vast, dense stands. New Jersey proved no different. 

Stiltgrass tends to establish itself along roadsides. Here it is growing in a green ribbon along Herrontown Road. Trails, too, provide an avenue for extending its reach, its tiny seeds carried on boots or the hooves of deer.

Though stiltgrass has covered large areas of woodland in the eastern U.S., we have found it worthwhile and even satisfying to counter its relentless incursions. Today in the Barden at Herrontown Woods, some volunteers pulled it out of a patch of native jewelweed along the edge of the parking lot. 

Nearby, on land where we have largely eliminated a massive clone of wisteria, stiltgrass was starting to move into the void. If nothing were done, this open woodland would have become a pasture of stiltgrass. But we have acted early enough to be able to remove all of this year's stiltgrass, dramatically reducing the seeds available for next year's crop. This photo shows the last patch before we pulled it. 

Interestingly, there are native grasses that look a little like stiltgrass, the main one being Virginia cutgrass (white grass), Leersia virginica. It has longer, narrower leaves that lack the silver stripe down the middle. As is a common ecological refrain, the native grasses "play well with others," not forming stiltgrass's massive, exclusionary stands. Some smartweeds like Lady's Thumb can also bear a resemblance. 

Friday, August 11, 2023

The Invasive Grass Fueling Wildfires in Hawaii

Hawaii didn't used to get pummeled by highly destructive wildfires. What has changed? A big part of the answer lies in the interaction between climate change and invasive species. 

Begin with a couple paragraphs buried in a NY Times article:

The area burned annually by wildfires in Hawaii has quadrupled in recent decades. Declining rainfall and rising temperatures have left the islands more susceptible to blazes, climatologists say.

Invasive grasses that are highly flammable have crowded out native vegetation in some areas, and climate change has exacerbated dry and hot conditions in the state, allowing wildfires to spread more quickly.

But what invasive species? A University of Hawaii website points to one that has been particularly destructive:
Guinea grass (Megathyrsus maximus), a nonnative invasive grass in Hawaii, forms dense stands that outcompete native plants and has very high fine fuel loads that greatly increase fire potential, spread, and severity.

Wikipedia describes guinea grass as a tough customer, growing ten feet tall. Though it can thrive in full sun, it can also tolerate shade, allowing it to invade native woodlands and thereby increase their vulnerability to fire during droughts. Native to Africa, the grass was introduced not only to Hawaii but also to south Texas.

How did guinea grass get to Hawaii (also spelled Hawai'i)? Wired provides an answer:

When Europeans arrived in the late 18th century and established plantations for growing sugarcane and pineapple, they also brought invasive grasses. Now the economics have changed, and those fields lie fallow. But the grasses have spread like a plague. “Those fire-prone invasive species fill in any gaps anywhere else—roadsides, in between communities, in between people’s homes, all over the place,” says Pickett. “At this point, 26 percent of our state is covered in these fire-prone grasses.”

This stuff is highly sensitive to short-term fluctuations in rainfall. The grass will grow like crazy when the rains come, then quickly desiccate when the landscape dries. “When we get these events like we’re seeing these past few days—when the relative humidity really drops low—all those fine fuels become very explosive,” says fire ecologist Clay Trauernicht of the University of Hawaiʻi at Mānoa.
An article in ABC News explains how the more intense and frequent fires affect the soil and human health: 
Elizabeth Pickett, co-executive director of the Hawaii Wildfire Management Organization, a nonprofit working with communities to prevent and mitigate fires, lamented the changes wrought by fire.

Invasive and fire-prone grass species have moved in over time and during a fire they can burn into native forests, which means the forests are replaced by more grass, Pickett said. The soil burns and sloughs off, leading to massive post-fire erosion that smothers coral, impacts fisheries and reduces the quality of the ocean water, she said.

The state is windy and the dust blows for years, harming human health, she added.

“When you lose your soil, it’s really hard to restore and replant. And then the only thing that can really handle living there in many cases are more of those invasive species,” Pickett said. “It’s systemic. Air, land and water are all impacted.”
A Philosophical Footnote
It's important to note that both climate change and the spread of invasive species are largely unintentional. Our world is threatened by excess carbon dioxide and other planet-heating gasses--lowly biproducts of our economy and lifestyles. We are used to thinking of collateral damage as minor and incidental, and tend not to judge people by what they do unintentionally. In fact, the cumulative impact of unintentional acts is the central threat we face. We live our days trapped in a predicament in which humanity, largely well-meaning, is allowed to collectively and unintentionally create problems, but not allowed to collectively and intentionally solve them. 

Additional reading: Thanks to a comment (see the critical comment and my response below), I found a couple more interesting articles about guinea grass. One gives a good overview of guinea grass as both an excellent, deeply rooted forage grass for cattle, and a weed that has disrupted ecosystems and croplands around the world. The other invests the grass with cultural connotations.

Other Invasive Grasses Fueling Fires in Hawaii

My friend Fairfax sent a link to another informative article that mentions three other introduced grass species fueling fires in Hawaii: fountain grass, buffel grass, and molasses grass. It also stresses that these and other highly flammable introduced grasses are altering fire ecology in the mainland U.S. as well.

What Guinea Grass Has in Common With Japanese Stiltgrass

Some people aren't aware the extent to which grasses affect our lives, for better and for worse. Corn is a grass, as are sugar cane, bamboo, and sorghum. In Princeton and up and down the east coast, the most dominant invasive grass is Japanese stiltgrass, which like guinea grass can grow in sun or shade, and uses what's called C4 photosynthesis to fix carbon from the atmosphere. Plants that use the C4 process--corn also being an example--are more efficient than other plants that use C3. Stiltgrass has invaded most areas of Princeton, growing from a zillion seeds each spring to blanket large expanses of woods. Wildlife don't eat it, so as it takes over, the landscape becomes increasingly inedible. I've long wished that someone would come up with a highly selective herbicide that would impact only C4 plants. If stiltgrass's impact on eastern habitats hasn't been sufficient to stimulate research, maybe the fire hazard in Hawaii will get researches to take a look.

Tuesday, July 18, 2023

A New Invasive Plant at Princeton High School

Here's a story about how an invasive nonnative plant can be accidentally introduced and quietly transform an area. It also shows how invasion can be regional but also very localized.

This is a big picture of a little yellow flower called birdsfoot trefoil (Lotus corniculatus). The clusters of flowers and especially the subsequent seedpods resemble the shape of bird's feet, and the tiny leaves echo this shape to some extent.

I hadn't knowingly seen it much, and only learned the name a couple years ago, but this year, 
it has spread aggressively along the grassy extension along Walnut Street at Princeton High School. I'd noticed a few the year before, but now it is dominant along a stretch in front of the Performing Arts wing and the Ecolab wetland. 
This year also, it is coating areas of an old pasture next to Herrontown Woods. In the pasture, it was probably planted intentionally as forage for cattle, but at the school, it surely was introduced accidentally.

Should we be concerned about either example of this nonnative rampancy? I sent an inquiry to a couple listserves of land managers, and received a tepid response. Birdsfoot trefoil is mostly a roadside weed, was the sentiment. It only gets a couple feet high, so will likely just stay in the background rather than stifle native species. 

But I have a vivid memory of a prairie walk I went on last year at the Kishwauketoe nature preserve in my home town in Wisconsin. At one point, leading us through a gloriously restored prairie, the botanist spotted a birdsfoot trefoil and immediately went over and pulled it out. Was it merely a pet peeve, or was his determination rooted in past observations of dramatic consequences if birdsfoot trefoil is allowed to spread? 

This short video shows how birdsfoot trefoil can alter the appearance, if not necessarily the composition, of a meadow:

I did a quick survey of school grounds and the nearby neighborhood by bicycle, and discovered that the infestation is limited to grass next to the extra wide sidewalks that were installed along Walnut Street a couple years ago. It probably hitchiked in on machinery or soil used in construction of the sidewalk. Another possible vector was the planting of new street trees right where the birdsfoot trefoil growth is now the most dense. Rootballs, topsoil, tools, heavy equipment--all can carry weedseeds.

This is an invasion that's in the very early stages, and could be easily nipped in the bud. For instance, I found a grand total of three plants on the middle school grounds. Five minutes of spot spraying with a selective herbicide now is all it would take to stop an infestation that will otherwise become intractable.

Another reason to take action is that it is poised to invade the new native meadow planting in the detention basin next to the tennis courts. In this photo, a few plants of birdsfoot trefoil grow just across the parking lot from the new native planting. Does the school want a native meadow, or a meadow that is thick with a nonnative species that appears capable of outcompeting many of the native grassland plants? 

Now, while the extent of the spread is limited, would be the time to take proactive action. 

Tuesday, July 11, 2023

Harrison Street Park: Contrasting Tales of Trees and Wildflowers

Most people drive by Harrison Street Park unawares. It's an old neighborhood park that lacks parking, and so mostly serves those who live close enough to walk there. Whenever I think to stop by this surprisingly spacious park close to Nassau Street, it's to check in on dreams living and remembered. 

One dream is bringing back the American chestnut. We've planted a number of chestnuts around town that are 15/16th native. They were originally crossed with a resistant asian chestnut, then backcrossed with the aim of ending up with a predominantly native chestnut tree that still carries the Asian species' resistance to chestnut blight. Some of these trees have proven susceptible to the blight, but two in particular have resisted the blight thus far. One of these is in Harrison Street Park, nearly 20 feet tall now. 

We also planted two native butternuts there, another native tree that has been marginalized by an introduced disease. It's good to see them thriving and starting to bear nuts. 

There's also an attempt by the town, successful thus far, to keep a grove of ash trees protected from the introduced Emerald Ash Borer, via systemic applications of insecticide. Another small grove of trees was planted through a citizen donation and collaboration with the Shade Tree Commission.

Other dreams for Harrison Street Park, involving wildflower plantings, have not done so well. Princeton Borough had great dreams for this park at one time. In 2006, they hired me to conduct an ecological assessment and write a stewardship plan. Then they hired a landscape architecture firm from Philadelphia to design improvements to the park. Neighbors offered many ideas and expressed many opinions. The old wading pool--a relic from a distant, more sustainable era when kids gathered in their neighborhood parks in the summer--was removed, the play equipment was updated, and a few new features were installed. 

Some $30,000 was spent on new native plantings that looked good for a year or two before going into steady decline. The idea was that neighbors would care for all these new plants. Of course, a drought promptly ensued. Some of the neighbors rose to the occasion to keep the plants going, but the extensive flower beds required more than an initial season of zeal. Neither the borough maintenance crews nor any of the neighbors had the training or interest to keep the flower beds weeded over the longterm. 

This flower bed is now a massive stand of Canada thistle and mugwort. 

The plant with the big leaves is a common weed in the midwest that is showing up more and more in Princeton. It looks like rhubarb, but is in fact burdock. 

There's a swale in the park that receives runoff from a private parking lot next door. These wet, sunny spots can tip the balance towards native species. A friend and I planted various floodplain species--joe pye weed, tall meadowrue, etc--but also planted Jerusalem artichoke, which is a native sunflower species with edible tubers. 

When planting an aggressive plant like a native sunflower, it's easy to believe one will follow up and keep its expansionist growth in check. That's almost never the case. The sunflowers has spread aggressively underground over the years, and have long since swallowed the other wildflowers in their dense growth. Each year the sunflower clone expands, as park crews mow around its fringe. 

We also planted a couple pawpaw trees there, but they were overwhelmed by the sunflowers. A couple black walnut trees sprouted on their own and had much better luck, somehow managing to rise above the sunflowers. Trees that plant themselves tend to be more successful than trees planted by people. On the upside, the sunflowers are so aggressive that they require no weeding, and there's a dazzling display of yellow in the fall. But, like some of the other plantings at Harrison St Park over the years, it's not what was originally envisioned. 

Tuesday, June 13, 2023

Poison Hemlock Popping Up in Princeton

When mathematician and Herrontown Woods volunteer Robert Budny reported that he had found lots of poison hemlock growing in his yard in Princeton, I was at first surprised. I somehow got it in my mind that he was talking about water hemlock--a rarely encountered native wildflower, of which I have come upon a grand total of one growing in Princeton's preserves. 

Robert was quite sure of his find, and said he'd experienced skin irritation while cutting the numerous plants down.

Then I saw this patch of white along Snowden, which too was surprising, since I pass there almost daily yet had never noticed before these tall plants covered in blooms. Maybe it was Robert's sharing of his backyard encounter that primed my eye to take notice.

These, too, proved to be poison hemlock, with broad disks of tiny white flowers. 

and lacy compound leaves. Other plants with white disks of flowers this time of year are the shrubs elderberry and silky dogwood, but they don't have finely dissected leaves like this poison hemlock. 

Though Princeton has many invasive species, those in the carrot family have been few. Goutweed spreads through some gardens. It gets mixed in with the intended plants and can be very hard to eradicate. My neighbor up the street was somehow able to do it, though, through sheer persistence. Wild carrot (Queen Anne's Lace) shows up occasionally along roadsides. It's a beautiful plant, but I've seen it become too much of a good thing in the midwest. Here's information on which members of the carrot family behave invasively in Wisconsin. It includes a useful description of this plant family.
"Many members of the carrot family (Apiaceae) are invasive in Wisconsin. These herbaceous biennials and perennials have alternate, compound leaves with sheaths at the base of leaves. Many small, 5-petaled flowers are arranged in compound umbels (several small umbels combine to make larger umbels). Of the species that are invasive, all have white flowers except wild parsnip, which has yellow flowers. Seeds form in pairs and stems are hollow at maturity."
There are other invasive plant species that, entrenched elsewhere in NJ, are just starting to show up in Princeton. Jetbead and Mile-a-Minute are examples. Catching these early and preventing them from spreading means fewer aggressive plants for gardeners and preserve managers to deal with in the future.

Related posts:

Tuesday, May 02, 2023

Wisteria Contained

As a land manager, having fought back many a runaway acre of wisteria in a woods, tangled with and been tripped up by its myriad tanglings, even walked upon the tranpoline-like, crazy quilt its runners can weave above the ground, I can still feel amazement when witnessing a wisteria molded by intention--first at its abundant flowering, and second, that someone has managed to keep its wanderlust in check. 

This house is a couple doors up from Hamilton Ave. on Linden Lane. Similar displays are likely in progress on the front porch of Morven and at Marquand Arboretum. They hearken back to an era when people had the time and interest to tend to their gardens, when gardening was a relationship, and gardens had personalities. My parents had such a garden in Ann Arbor, MI, where I would trim the wisteria growing up their patio trellis. The flowers were pretty, but never reached the magnificence of this display on Linden Lane.

The wisteria in this photo is thankfully in the front yard, along a town street. If the owner ever lost interest in carefully maintaining it, there's no nature preserve nearby for the wisteria to swallow, only the house and the neighbors' yards. Having witnessed and reckoned with the unintended consequences of inattention, I can see both the beauty and the Burmese python-like potential lurking within, its expansionist nature for now contained.

Related posts:

Where Vines Tackle Trees: A wisteria that grew so thick you could walk on its web of runners without touching the ground. 

Another Perilous Embrace--Wisteria and Horse Chestnut: When wisteria gets loose in a neighbor's yard.

Friday, April 15, 2022

Lesser Celandine Alert!

It's time for the annual call to action to prevent lesser celandine from taking over all of Princeton. Also called fig buttercup, it's a highly invasive nonnative plant that is spreading rapidly, yard to yard and into parks and nature preserves, where it degrades habitat for wildlife. It thrives on homeowners' indifference and inaction, so I've been doing what I can, urging town officials to defend our parks and preserves, urging homeowners to take action in their own yards, explaining that herbicides are not anti-nature if they are used selectively and medicinally. My letter to the Town Topics and other local publications starts like this:

Blooming in many people’s yards right now is a small yellow flower that, upon closer inspection, proves not to be a dandelion. Variously called lesser celandine or fig buttercup, its radical invasiveness triggers a predictable progression of emotions in the homeowner. Delight at its pretty flower soon turns to alarm as year by year it takes over the yard, spreading through flower beds, across lawns and into neighboring properties. What may start as a few scattered, harmless-seeming clumps quickly becomes the equivalent of a rash upon the landscape. Unlike the dandelion, lesser celandine also spreads into nature preserves. Poisonous to wildlife, it forms thick stands reminiscent of pavement. Over time, our nature preserves become less and less edible to the wildlife they were meant to support. Native diversity shifts towards non-native monoculture.

Below are some photos to help with identification, and here is a link that includes suggested means of stopping it from taking over your yard. Though the link says only to spray through early April, I'd suggest that spraying is helpful for as long as its leaves are green. Lesser celandine is a spring ephemeral, meaning that it comes up early, then dies back in June, going dormant until the next spring. Gardeners who like to dig up plants of this or that to give to friends should be aware that, if their yards have been invaded by lesser celandine, some of it may hitchhike in whatever plants they dig up later in the season to give away. They may unwittingly be giving a fellow gardener the beginnings of a major headache.

Lesser celandine is poisonous, and yet some websites declare it edible and offer recipes. Why the contradiction? Apparently, lesser celandine accumulates toxins later in the spring. The toxins break down during cooking or after drying. Still, one takes one's chances trying to eat it, and, alas, wildlife don't cook.

I've seen bees collecting pollen and nectar from the flowers, which is all fine and good, but this doesn't compensate for the inedibility of the leaves. The invasion of our lands by nonnative plants that wildlife don't eat essentially shrinks the acreage of functional habitat in Princeton, even though a great deal of open space has been preserved. Thus the need for management.

Given that some areas of Princeton have been overrun by lesser celandine, it's important to defend those areas that have not, by closely monitoring and spot spraying where the plant is just starting to move in. Invasions begin with just a few plants here and there. An absolute minimum of herbicide is needed to easily defend these areas. Lesser celandine can easily be distinguished from dandelion. Walk the grounds before the grass gets mowed in the spring and while the plant is blooming. For lawns, a product like Weed B Gone works. For other areas, a 2% solution of glyphosate does the trick. Since glyphosate can take a week to show visible effect on the plant, it's best to spray early in the spring so that there's time to see results and spray any areas missed. For those near wetlands, wetland-safe formulations of glyphosate are available, so Roundup is not the only option.

In terms of aesthetics, lesser celandine's dense, exclusionary growth does to the landscape what people badly afflicted with narcissism do to social situations. A woodland that once hosted a diversity of native wildflowers becomes, when overwhelmed by lesser celandine, one species' declaration of Me! Me! Me! 

Here's what it looks like up close.

Here's an example of the blotchy appearance an early invasion creates on a lawn. These blotches expand until the whole yard is coated.

The closest lookalike in the lawn is the violet, whose leaves are darker, more curled, and more toothed along the edges. 

Sunday, September 19, 2021

Mile-a-Minute Spreading into Princeton

 One of the more noxious invasive plants that has been spreading across NJ is Mile-a-Minute. It's a prickly vine that, though an annual that must grow back from seed each spring, grows so fast that it can cover large areas of roadsides and field edges. Over the past several years, I've been knocking out small infestations at the Princeton Battlefield and near Rogers Refuge, but this year I'm finding new patches springing up around town.

Then, driving my daughter to MarketFair along Canal Pointe Blvd a week ago, I saw a massive infestation that surely is a major source of the seeds that birds are then spreading across Princeton. 

The vine has a distinctive triangular leaf. Berries are just beginning to ripen. If you encounter it, put some gloves on, pull it out and put it in the trash. Putting it in the compost would allow the seeds to spread. 

The infestation along Canal Pointe Blvd is behind 701 Carnegie Center Drive. In the aerial, you can see rows of solar panels over the parking lot. To the left of the solar panels is a big mowed lawn, and to the left of the lawn in the photo is the unmowed land upon which the Mile a Minute is growing. My friend Peter researched the owner, which on the deed appears to be "BXP Carnegie Owner, LLC%G". The land has a farm easement, so is only valued at $39,000, which means the owner is paying next to no taxes to hold very valuable property, meanwhile expediting the spread of Mile a Minute and the associated nuisance it will cause. 

It's hard to photograph the cocktail of invasive species at the site. The white flowers are of white snakeroot, a native wildflower, which is besieged by a layer cake of stiltgrass, porcelainberry, and Mile a Minute climbing on top of it all. 

Further down the road is a series of trees damaged, perhaps by a small tornado or similar localized intense winds as the remains of Hurricane Ida came through on Sept. 1. Similar damage to trees was seen in Princeton Battlefield, where a row of mature white pines along the edge of the field was decapitated.

What we're seeing is the increasing impact of plants out of place (species that turn invasive after being introduced from other continents) and carbon out of place (carbon fuels extracted from underground that we burn, thereby releasing additional carbon dioxide into the atmosphere). Our machines have increased global warming CO2 by a whopping 50% over pre-industrial levels thus far. This year has felt like a radicalization of both invasive species and climate change. 

Saturday, September 18, 2021

Butler Tract Meadows Restoration?

This is the story of what can go wrong if you plant a native meadow and then don't take care of it. Princeton University has been installing some native meadows, and some have done a lot better than others.

Just off of South Harrison Street, framed by Sycamore Rd and Hartley Ave, are some meadows that were planted in 2016 following the university's demolition of the Butler apartments. It was a well intended succession from graduate housing to native meadow, and when I took a look in 2019, the meadows were still hosting diverse native wildflowers. 

Two years later, these signs appeared: 
"Butler Tract Meadows is under an invasive management program for this year."

For most of the summer, it wasn't clear what that meant. The signs appeared early in the growing season, but I could find no sign of any action. 


This photo tells the story of what happened to the native meadow over the course of five years. The usual nonnative invasive species moved in and began to dominate, with mugwort foremost among them. The white flowering plant on the left is Japanese knotweed, which can form large monocultures as well. Bamboo is getting a foothold in the lower lefthand corner of the photo, and in the distance can be seen the sproutings of black locust, a native tree that nonetheless can move aggressively into native grasslands. 

Sericea lespedeza (L. cuneata) is another super-aggressive nonnative. Newer on the Princeton scene, it can rival mugwort in its capacity to displace diverse native plants, for instance along the gasline right of way that crosses the Princeton Ridge. 
And here's crown vetch, which climbs over everything around it. Both crown vetch and Sericea lespedeza were planted extensively along freeways to control soil erosion, reducing one environmental harm while creating another. 

I did notice a few native species still present, including this wild senna. The only practical means of shifting the balance back to the native species on this scale is through use of herbicides. Some people lump all herbicides together and pronounce them evil poisons--an indiscriminate rejection borne of their often indiscriminate use. But there are many kinds and many formulations, some far safer than others, and the aim as with medicines for people is to use as little as possible, in a targeted way. 

The way to reduce the use of herbicides is to be proactive and intervene early to kill the invasives when they are still few in number. That would have been something to do from the beginning, back when a more targeted, minimalist approach was possible. 

My friend Basha who lives across from the Butler Tract told me they had finally done some spraying. A week later, I took a look. Here you can see the black locust tree sprouts turning brown while many other invasive plants appear untouched.
This big patch of mugwort shows some sign of dieback, but pretty uneven results thus far.
I'm guessing that patch in the background of this photo was crown vetch. In the foreground is probably common cinquefoil (Potentilla simplex), which is native but a very rapid spreader.

It will be interesting to see how this goes. My experience is that institutions have always understood that lawns and landscaping take ongoing care, but they have yet to grasp that more naturalistic areas like meadows also need ongoing intervention. At the Butler Tract, they seem to be trying to figure out what that means.

Friday, August 06, 2021

Suburban Monocultures and Insect Decline

Thoughts about insect decline and some field observations came together at the corner of Harrison Street and Terhune the other day when I headed to the optical shoppe to get my glasses adjusted. 

The lawn outside the building could be described as an ecological desert, a large expanse of closely cropped grass whose only purpose is to flatter the building. And yet it seems right to our culturally conditioned eyes, which view it as greenspace even if it constitutes an ecological void. 
Whereas a lawn is an intentional monoculture enforced directly by people, this expanse of Sericea lespedeza, also called Chinese bushclover, is enforced by the aggressiveness of the plant itself. I've watched this field, on land next to the shopping center, gradually become overwhelmed by the introduced species, whose foliage is spurned by the local wildlife, including insects.

Thirty feet away, the Japanese stiltgrass is having its way along Terhune, as it does along so many roadsides. This displacement of diverse flora, whether suddenly in the form of a development, or gradually along roadsides or in abandoned fields, surely is playing a big role in the diminished habitat for the insects upon which ecosystem foodchains depend.

Interesting to see the patch of lighter green in this photo. That's native sensitive fern, which is clearly holding its own against the stiltgrass. But this is one small victory in a landscape that has shifted dramatically towards monoculture. Imagine what it would be like to walk into a supermarket and find only cardboard on the shelves. That must be how an insect experiences so much of the suburban landscape.

Note: Just noticed that local birder and Princeton professor David Wilcove recently co-wrote an opinion piece in the Washington Post entitled "We need to figure out what's happening to the bugs--before it's too late."

Thursday, March 11, 2021

Be On Guard for Lesser Celandine

(This post is from 2021. Click here for more recent posts about nature.)

From backyards to front yards to curbsides to parks and nature preserves, a small invasive flower is on the march. Dominating the landscape in early spring with its yellow blooms, it turns March into LOOK AT ME, ME, ME!, because that's all you will see when lesser celandine coats the ground. Just to hoodwink homeowners, the name "lesser celandine" has sometimes been supplanted by the name "fig buttercup," but it's all the same plant, whose latin name is Ficaria verna

My posts about the plant date back to 2007, when I heard people mistakenly calling it "marsh marigold," which it most emphatically is not. Back then, lesser celandine was most entrenched at Pettoranello Gardens and rapidly spreading downstream into Mountain Lakes. Hopefully, when Princeton hires an open space manager, a more coordinated effort can be launched to reduce the plant's spread and protect areas not yet infested. Homeowners tend to like the plant at first, then become appalled as it begins taking over the yard and spreading to the neighbors'. 

Use herbicides on lesser celandine? The nature of good and evil.

Those who care enough about their yards and the local ecology to want to stop the plant's spread may also feel qualms about using herbicides, which are the only practical means of control. Removal by digging is cumbersome, time-consuming, and adds unnecessary weight and bulk to your trash can. I encourage people to think of herbicides for nature the same way we think of medicines for people. We know all medicines have some level of toxicity, but we use them in a minimal and targeted way to protect our health. Doesn't nature deserve the same sort of intelligent intervention? It's important to make a distinction between spot spraying for lesser celandine and the blanket application of pesticides and chemical fertilizers on lawns. Glyphosate and Roundup are not synonymous. There are wetland-safe forms of glyphosate available online, not made by Monsanto. If treating lesser celandine that has invaded lawns, use an herbicide that is selective for broadleaf plants so that the grass survives.

While avoiding blanket condemnations of herbicides, I also like to avoid thinking of invasive species as "bad plants." Like so many of the problems that plague us, they are "too much of a good thing." Unfortunately, though it might be tempting to keep a few lesser celandines in the yard, its super aggressive behavior makes that very risky. Best to eliminate it altogether. Winter aconite, on the other hand, is a nonnative that looks a lot like lesser celandine but has not to my knowledge spread into natural areas.

Selected past posts:

2019: Fig Buttercup--Little Flower, Big Problem - Photos of fig buttercup's (lesser celandine's) spread, along with a discussion of why this invasive species creates more problems than other common invasives.

2018: A World Paved With Fig Buttercup? - Lesser celandine's other common name is fig buttercup. This post documents in photos and text the astonishing spread of this plant in the Mountain Avenue neighborhood.

2017: Winter Aconite and Fig Buttercup--Related Flowers, Contrasting Behaviors - These two early blooming yellow flowers look very similar, but behave very differently.

2016: Letter On Lesser Celandine Strikes a Nerve - a letter in the Town Topics that got quite a response

2016: Alert, Monitoring for Lesser Celandine - This post includes links to treatment options.

2015: Marsh Marigold vs. Lesser Celandine - Lesser celandine is frequently mistaken for the native marsh marigold, which is a larger plant and very, very rarely seen.

2013: Will the Real Marsh Marigold Please Stand Up--a Confusion of Yellows - Some photos help distinguish lesser celandine from marsh marigold, dandelion, and celandine poppy.

2007: Pretty, but... - My earliest post on lesser celandine.

Tuesday, January 19, 2021

Video Presentation on Invasive Species

On 11.11.2020 I presented a zoom talk on invasive species as part of a series of monthly talks sponsored by the Sierra Club of NJ--Central Group. The talk was entitled "Invasive Species and the Pandemic: Thinking of Nature as a Body." Thanks to Kip Cherry for inviting me to speak, to Chuck McEnroe for film editing, and to PrincetonTV for posting the talk online.

In the talk, really two talks in one, I tell how vanquishing aggressive invasive species has often been the first step towards creating special places for native diversity to flourish and people to gather. In the second part of the talk, I discuss how my experiences in climate change theater and land management led to the concept of nature as a body. 

Tuesday, September 22, 2020

Autumn Clematis and the Really Big Show

Even now, as the flowers begin to fade, 

autumn clematis makes this lamppost look like it's wearing a voluminous fur coat. 
It's been a good year for autumn clematis, whose big floristic show revved up in these parts nearly a month ago, caught in a photo where a cascade of flowers-to-be was piggybacking on a neighbor's fenceline. 

There is great appeal in the blooms, and yet this vine should come with a warning sign.

In my mind, though not in the garden, I pair the nonnative Autumn clematis (Clematis terniflora) with the native virgin's bower (Clematis virginiana), which also has white flowers and a sprawling habit. An easy way to tell the two apart is the leaves, which are toothed in the native, rounded in the nonnative. The native's flowering comes earlier in the summer and lasts a week rather than a month.

Together they tell a familiar story, in which the native has become comparatively rare. Years back, I took this rarity to mean that the native was less aggressive, but in fact the native when planted in the garden has proven just as hard to control as the introduced species. While sending up vines that grow over other plants, as you'd expect of a vine, both also spread underground, popping up in all sorts of places where you had other plans. 

Why is it the nonnative that can be seen covering a whole side of an abandoned parking lot in Montgomery north of Princeton? 
or lining the road to Cape May Point State Park? 

There are books that claim that nonnative invasive species are somehow superior to the natives, and that we should embrace these "winners" rather than counter them. Hopefully that dubious premise has faded into obscurity, unlike so many other dubious premises that now strut their stuff on the national stage.

More likely, the autumn clematis's capacity to grow unhindered is due to its unpalatability to deer and other wildlife. That would explain why the native virgin's bower is rare in local nature preserves while it runs rampant in my garden in town, where deer seldom venture. 

Periodically, I head down the great eastern piedmont from Princeton to North Carolina, where I've been involved with saving some rare habitat known as piedmont prairie. This small remnant on the outskirts of Durham, NC contains a clematis that will seem odd to anyone accustomed to clematis being a vine. This one, called curly top, Clematis ochroleuca, grows a foot or two tall in full sun and special soils formed from the underlying diabase rock. Princeton has lots of diabase rock along its ridge, which also hosts rare species, though not the same ones as in NC. 

The name "curly top" might come from the way the flowers curl downward, or from the curly seedheads that are also characteristic of the more common kinds of clematis. 
Another clematis in the piedmont prairies of NC is leatherflower, Clematis viorna, a small vine whose flower also points downward. 

Witness a high quality piedmont prairie, and you'll see how rich and diverse an intact native habitat can be. Though cheated of the periodic fires that used to sustain them, prairie remnants have persisted here and there, mostly under roadside powerlines where trees were not allowed to shade them out. I've rescued plants from a few that were being lost to development, and marveled at how each shovelful would contain four or five species. Nature was demonstrating how co-evolution moves towards a rich coexistence. Presumably, each species is limited in some way, most likely by herbivory, from running roughshod over the others. 

Witness that, and a monoculture of autumn clematis will look both showy and disturbing.