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.

The Second Forest of Institute Woods

In the Institute Woods, towards the end of the day, towards the end of autumn, it's not just the trees that cast long shadows. In the understory, a shadow forest grows, composed mostly of nonnative shrubs--winged euonymus, linden viburnum, asian photinia, shrub honeysuckle, multiflora rose and privet. Having evolved on a different continent in a different climate, they hold their leaves long after most of the native woodies have dropped theirs. Dominating the understory, these shrubs and vines constitute a second forest that serves up a second autumn, shedding their conformist green to show late-season reds and golds. 

There are second forests all around Princeton and beyond. The light green close to the ground in this photo is honeysuckle shrubs along Terhune Rd.

Here, viewed from the Streicker Bridge over Washington Road a week or two ago, are Norway Maples pushing up into the canopy of mature native oaks, beech, and blackgum, some of which are two centuries old. 

Bamboo at the Princeton Battlefield, bordering the Institute lands, offers another variation on the theme.

The different colors of the second forest provide a convenient code for easy long-distance identification. The pink here, down near the Friends Meeting House entrance to Institute Woods, means you're looking at winged euonymus. If it were growing in full sun, the color would be a vivid red, from which comes its other common name, burning bush. 

Here the pink of the winged euonymus mingles with the still green multiflora rose. 

Linden viburnum has its own distinctive fall color, 

as does Asian photinia, whose leaves tend to be broader towards the tips. It's usually more golden than this photo shows, and in Mountain Lakes and along Princeton Pike has turned whole woodlands golden this time of year. 

Mingling with the photinia here is the viny ever-green Japanese honeysuckle. 

Wineberry, with its fuzzy purple stem, is another Asian species with lingering green in late fall. 

Privet holds onto its green as well, here growing up around the tan stem of a shrub honeysuckle. 

Add global warming, which is bringing unusually warm and comfortable autumn days, and the feeling of gratitude for unseasonal warmth and color begins to  mix with a foreboding about the ecological consequences. Awareness creates an emotional undertow pulling against the uplifting effect of weather and color. The second forest flourishes in part because it is inedible to wildlife, which prefer and depend upon native species for food. The colors that greet our eyes this time of year signal a diminishing edibility for the forest's inhabitants. 

Four plaques tell the story of how the Institute Lands were saved from development in 1997, a half century after they were acquired. Though a couple key elements are left out--the Lenape Indians and Oswald Veblen--it is an extraordinary story, listing the major donors, 

the Taplins who led the way,

the coordination of governmental, institutional, and nonprofit entities that in NJ has been so effective in saving land. 

You can click on each photo to hopefully make it large enough to read.

Here, on this plaque, would have been a good place to mention the Lenape Indians as early occupants and stewards. A whole additional plaque could be dedicated to telling of Oswald Veblen's role as primary instigator of acquisition. As partially told on the IAS website, and more fully told by George Dyson in a talk at DR Greenway, Veblen convinced the early Institute leadership to acquire the land, then did the legwork necessary to bring all the parcels together. Over ten years, beginning in 1936, Veblen laid the foundation for open space in Princeton, with the acquisition not only of the Institute lands but also the 100 acres on the east side of Princeton that he and his wife Elizabeth later donated as Princeton's and Mercer County's first nature preserve, Herrontown Woods.

It's interesting to look at the chronology of open space initiatives in the Princeton area. The Institute lands were acquired between 1936 and 1945. In 1949, the Stonybrook Millstone Watershed Association was formed. Around 1959 Herrontown Woods was officially opened. In 1969, the Friends of Princeton Open Space came into being. In 1989, the DR Greenway was formed. Whether there's meaning in the 20 year increments of their foundings, all three nonprofits played a role in purchasing from the IAS the conservation easement that now protects the Institute lands from development.

Preservation tends to be celebrated more than management, so it's good to see there's a plaque celebrating maintenance, at least of the trails. The leadership and persistence needed to keep the woods accessible was first provided by Veblen, then later by mathematician Paul Dirac, then still later by what appears to be lasting funding in 2008 provided by Addie and Harold Broitman.  

Though the land is preserved, and the trails continue to be kept clear, and the richness of the Institute Woods has been researched and documented by Henry Horn and others, there is still a missing element for insuring the Institute Woods' longterm health. It's not clear that the woods hold the same biological richness seen in Veblen's time, or even Henry Horn's. With habitat restoration and deer management, we might lose the colors of the second forest, but gain a second preservation, this time saving the flora and fauna not from developers but from ecological imbalance and attrition of native species over time. 

The first preservation, in 1997, prevented intentional alteration of the woods by developers. But the woods is still being altered indirectly, unintentionally, through the invasion of introduced species and the banishing of predators that once kept deer numbers in check. The second preservation takes responsibility for the unintentional changes humanity has unleashed, and requires us to be active and informed participants in the forest's ecology. Clearing the invasive species that crowd the forest, and reducing the intense browsing pressure of deer, would begin to bring back the lovely vistas and sweeps of wildflowers that surely helped inspire the community investment in saving the land more than twenty years ago. 

The Grass That Ate The King's Highway

There's a curious sight as you approach Montgomery from Princeton on Route 206. Something is eating the Kings Highway. 

That something is Phragmitis, most frequently encountered in its highly aggressive, non-indigenous form. In wetlands, it displaces even the tough native cattails. On the other side of town, in Rogers Refuge just below the Institute Woods, we've been working for years to keep it from taking over the marsh.

Spreading its tall tassels along freeway ditches, it dominates the New Jersey meadowlands and can be considered a worldwide weed. Its scientific name is as sprawling as its growth habit: Phragmites australis subsp. australis. The native version, less aggressive and now hard to find, is termed subspecies americanus.

One source describes the introduced variety as "a hardy species that can survive and proliferate in a wide range of environmental conditions." Sometimes it's planted intentionally, to treat wastewater or reduce soil erosion. Mostly, it plants itself, then expands relentlessly, oblivious even to normally intimidating barriers, like asphalt.

The common reed is a grass, like bamboo is a grass. Unlike bamboo, which lives for decades without flowering, Phragmitis blooms each year, combining abundant seed production with bamboo's powerful capacity to spread underground. That combination makes it a transformative force not only in nature but in human habitats as well. 

Invasive Mile-a-Minute Spreading at Princeton Battlefield

Ever find yourself caring deeply about something the rest of the world ignores? We all pick our battles, and here's a really good one for the Friends of Princeton Battlefield and/or our governing institutions to pick.

Princeton has been graced in many ways of which it is not even aware, and one of those is the up-to-now absence of Mile-a-Minute, a thorny annual vine that grows up and over everything if allowed. Gardeners beware. This one's particularly nasty, and though it has gained a foothold in nearby areas, I've encountered it in only two locations in Princeton. One location is the Princeton Battlefield. The other is on the gravel road in to Rogers Refuge. Each year I pull it out, but by the time I remember to do it, a few of the vines' little blue berries have matured, so the infestation has been growing.

Obviously, my efforts are not enough. The town of Princeton has fortunately hired the NJ Invasive Species Strike Team in recent years to treat invasions by new species, but the Battlefield is state owned, and because of a lack of intervention it is now serving as a seed source that will affect all Princetonians, and not only for Mile-a-Minute.

Another issue at the Princeton Battlefield is the massive invasion by porcelainberry--a vine that rivals kudzu in its capacity to sprawl over anything and everything. Its overwhelming presence may seem to dwarf the problem with Mile-a-Minute, yet it can also be seen as proof that we really need to catch these invasions early, before they get out of control. Porcelainberry is not only at the Battlefield, but is also dominating large areas all along the Stonybrook in Princeton.

Here are the copious berries produced by porcelainberry vines as they smother the flowering dogwoods planted in 1976 for the nation's bicentennial. The berries turn pretty colors--blue, purple, pink, or white--thus the name, and the original appeal of the plant. But the plant has escaped the usual checks and balances that otherwise sustain balance in nature.

Birds eat the berries of porcelainberry and Mile-a-Minute, thus the concern that what's allowed to grow at the Battlefield will impact the rest of Princeton.

The Friends of the Battlefield group, by the way, has been doing a great job knocking out big stands of bamboo around the Clark House during its annual workday in April. Look in the distance in the photo and you'll see an open field, with only a small remnant of bamboo back near the woods.

But bamboo doesn't spread by seed, and so poses no threat beyond the Battlefield's borders. Volunteer sessions can slow down porcelainberry and Mile-a-Minute a bit, but for any lasting benefit, we need to get some professional intervention. Maybe the Friends of the Battlefield could apply for a grant.

In the meantime, be on the lookout for its distinctive triangular leaf, put on some gloves, and pull it out.

A World Paved With Fig Buttercup?

There are many types and degrees of invasive behavior in plants. Dandelions are weedy in lawns but cannot survive in the shade of a forest. Japanese maple and Rose of Sharon may seed prolifically in a garden, but rarely show up in the nearby nature preserve. Bamboo, kudzu and Asian wisteria become like castles in the landscape--formidable, exclusionary, and deeply entrenched but limited in extent. They form dramatic, isolated clones that fortunately leave most of the forest untouched. Stiltgrass by contrast is a frail annual easily pulled, which nonetheless can have a far greater impact, coating the ground of large swaths of forest with billions of plants. It thrives in shade but tolerates sun, spreading into garden beds and lawns.

We, with our big brains and bodies, are built to take on large, distinct foes, yet quickly grow discouraged when faced with a threat that is small but hugely numerous, whether it be an overabundance of carbon dioxide in the atmosphere, plastic in the ocean, those tiny odorous house ants in the kitchen, or a ubiquitous weed in the garden. That pile of papers on the desk falls into this category as well. If the small, numerous thing is a disease pathogen that attacks us directly, we have strong institutions that engage to defend us. But if the small, transformative force represents an indirect threat, impacting our environment--our oceans, landscape or climate--rather than us directly, we lack both sufficient institutions and the will to resist. This can be considered society's achilles heel.

As a local example, our big-little hamlet of Princeton is being gradually paved over by a little plant that is pretty, and seemingly benign, yet is also extraordinarily aggressive, poisonous to wildlife, and overwhelming in its numbers and rate of spread. By mid-summer, it will have faded back into the ground, but in spring it looks like an expanding rash coating the land. It numbers in the billions, and cannot be easily pulled. Even its common name is hard to get a good hold on, with "fig buttercup" having displaced "lesser celandine" because the plant has the buttercup flower and fig-shaped tubers. The scientific name is Ficaria verna, with verna referring to its spring growing habit.

In the photo is an advanced invasion in Pettoranello Gardens that long ago spread downstream to Mountain Lakes Preserve. The more land it covers, the less edible the landscape is for wildlife. Our investment in open space acquisition is undermined as the acreage of functional wildlife habitat continues to shrink due to displacement of natives by introduced species that wildlife won't eat.

Now the fig buttercup is spilling into the nearby neighborhood along Mountain Avenue, spreading down-slope from one yard into the next. This patch spread through the fence, and through the neighbor's yard,

then popped out under the fence on the other side, ready to head further down the street. This species behaves like plastics pollution in that it becomes widely spread for lack of any organism able to eat it. Nature's checks and balances, developed through eons of co-evolution and adaptation, are circumvented when a new species like fig buttercup is introduced from another continent.

Here it is at Elm Court, a few blocks further on, poised to spread into and eventually coat their detention basin.

There used to be some solace in thinking that fig buttercup was limited to low, wet ground, but here it has become established along a slope next to the stage at Pettoranello Gardens. Audience members will slip on it, pick up some of the underground bulbs in the treads of their shoes, and transport the plant to new locales. What will stop it from eventually paving all of Princeton?

For contrast, here is the native marsh marigold, with which the fig buttercup is often confused. It's growing on the edge of the stream in Pettoranello Gardens because I planted it there a few years back. It's bigger and more showy, but doesn't take over like the fig buttercup. This is the classic example of how many landscapes have become dominated by invasive introduced species, while the native plants become rare.

Another attractive native yellow flower in spring is celandine poppy (unrelated to "lesser celandine"). I've never seen it growing naturally in the Princeton area, but it is used in landscaping. It has a nonnative lookalike that can be weedy but not as invasive as stiltgrass or fig buttercup.

Because fig buttercup is so aggressive and so hard to remove manually, careful use of herbicide is really the only means homeowners and preserve managers have to prevent it from getting established and ultimately taking over. Early detection and rapid response are the best recipe for minimizing herbicide use. We can't wait a million years for nature to adapt and re-establish balance, as one of the more bizarre books on invasive species has claimed.

Maybe research could eventually lead to a biological control being introduced to limit the fig buttercup's aggressive spread, but that requires that institutions be in place that can afford to do the many years of research and testing required, with no guarantee of success. In the meantime, fig buttercup continues to pave Princeton, one nature preserve and yard at a time.

Princeton Battlefield Clean-up -- March 31

Each year, the Princeton Battlefield Society and the local chapter of the Sierra Club team up to have a volunteer workday at the Battlefield. Though the Battlefield is a state park, the state limits its maintenance of the grounds to lawn mowing, leaving the rest of the park's greenery to grow as it may. Two very aggressive introduced species, bamboo and porcelainberry, have run rampant, impinging on trails and overwhelming some historic plantings such as the dogwoods planted in 1976 to celebrate the nation's bicentennial. As part of the Friends of Herrontown Woods' outreach, I'll be leading volunteers interested in sustaining the dogwoods planted around the perimeter of the park on the Colonnade side.

Anyone who'd like to join in, check out the flier below, and rsvp at https://www.theprincetonbattlefieldsociety.org/. If you can, bring workgloves, loppers, and handsaws. Here's a writeup on last year's spirited event, with our state senator Kip Bateman in attendance.

Bamboo at Princeton Battlefield Gets its Summer Cut

This past Saturday, four of us gathered for a well-timed intervention at the Princeton Battlefield. The Friends of Princeton Battlefield had cut down a patch of bamboo in the spring, but the roots had quickly sent up a new crop of shoots--essentially foliar solar panels that would quickly begin resupplying the bamboo's powerful root system. By following up and cutting the new shoots, we deprived the roots of any return on their investment in new infrastructure. This is the third year we've done this, and each year the job gets easier. A massive stand of bamboo has been reduced to modest sprouts easily managed.

Thanks to volunteers Jill Warrington, Andrew Thornton, and the leader of the Friends of Princeton Battlefield, Kip Cherry. My participation was a bit of outreach from the Friends of Herrontown Woods, on the other side of town.

15 Flowering Dogwoods Rescued from Smothering Vines at Princeton Battlefield

Saving legacies is what Princeton Battlefield is all about, and one legacy we sought to save during a big workday organized by Kip Cherry were flowering dogwoods planted for the nation's bicentennial in 1976. I do most of my habitat restoration work at Herrontown Woods in eastern Princeton, but have been visiting Princeton Battlefield periodically to help tame bamboo monsters, care for native chestnuts and prevent vines from completely smothering the dogwoods. Having ten able and spirited volunteers at this year's Battlefield Society's Clean-up Day made real progress possible.

Kip Cherry (front left) began the afternoon with a moving description of the great battle that took place there in 1777.

Ten of us then headed across Mercer Street to liberate the flowering dogwood trees lining the edge of the field. The dogwood flower buds, poking through the drapery of vine growth, provided inspiration, with their promise of beauty in the spring, and nutritious berries for the birds in fall.

This was the curtain of vines we cleared away with loppers and pruning shears, while dodging poison ivy and the thorns of multiflora rose.

Here's a "before" shot, showing porcelainberry draped over three dogwood trees. (photo from last fall in a previous post)

And here's the "after" shot, taken from underneath the rescued dogwoods. We worked to create an open space between ground and lower limbs so the vines cannot easily climb back up.

Thanks to our brave and skillful crew, who came from near and far to liberate fifteen dogwoods over the course of three hours.

I liked this pose when the work was done. As always happens on workdays, there were good conversations to go along with the physical work. I gained some Veblen House-relevant information about Long Island and Connecticut, and heard some positive testimonials about electric cars like the Chevy Volt, which combines 60 mile battery range with a backup gas engine. One owner said she'd spent only $9 on gas since last summer, and hadn't noticed any rise in her electricity bill from charging up the car at home. While restoring some history, it was good to hear the future in the form of electric cars might be at hand as well. The same thinking goes into saving legacies, whether they be dogwood trees or the world's climate.

Senator Kip Bateman and Assemblyman Reed Gusciora dropped by to help out.

Here is Kip Cherry's summary of the day:

"Our Clean-up Day was a big success! The sun peaked out, and from all reports everyone had a great time, the Park looked a lot nicer when we were done, the CWT t-shirts were well received, and the Sierra Club came through. Senator Bateman and Assemblyman Gusciora both arrived and put their shoulders to the wheel. A large group of kindergartners picked up fallen sticks, while others removed invasive porcelainberry vines from dogwoods, cut down bamboo, and cleared encroachment along the pathway to the Quaker Meeting House. Special thanks to Kim Gallagher and Steve Hiltner for leading teams, and to Gary Nelson and Randy Riccardo for their hard work!"

Porcelainberry: the Vine that Ate Princeton

Here it's Friday of National Invasive Species Awareness Week, and nary a post about invasive species!

First, readers should be aware that there are contrarians out there, writing books, articles and opeds, trying to deny that invasive species are a big problem. It's fascinating to analyze their mental gymnastics and deceptions, which are similar to those used to deny the reality and danger of climate change. I've picked apart their faulty logic in posts that can be found at this link.

Now, on to our porcelainberry tour of Princeton. You won't find it in shady areas, where other invasives like stiltgrass, garlic mustard and winged euonymus thrive. Rather, porcelainberry threatens to smother all of those sunny openings and edges that shade-intolerant plants depend on for survival. Porcelainberry is related to our wild grape, but much more aggressive. Your first impression will be, "What lovely multicolored berries!"

Your second impression, as it climbs up the stems of your shrubs, like this elderberry, might be, "Oh, a little rambunctious, but those berries are so pretty!"

Your third impression, as it turns your yard or park into a monocultural topiary, will be more along the lines of, "OMG! HELP!" No, this is not kudzu growing along a freeway down south. This is porcelainberry winning a modern day Battle of Princeton, with stealth and persistence far beyond anything we distracted humans might muster.

This is what a nearby patch looks like in December, just down the road from the Princeton Battlefield, along Quaker Rd between Mercer and 206. Invasive vines and shrubs can seem less overwhelming in winter, which is actually a good time to remove them. In spring and summer, though, all that growth energy can be intimidating.

And this is what porcelainberry is doing to the sunnier portions of our lovely nature trail off the DR Canal Towpath near Harrison Street. The blackbirds may say hello to the berries, but it's bye bye to the diversity of native wildflowers underneath that foliar blanket.

Turns out porcelainberry's a soccer fan. Here it is in the cheap seats at Princeton University's Roberts Stadium, at one end of the field,

and at the other.

Here it is (light blue and pink berries) in that "second impression" stage, climbing over a honeysuckle shrub (red berries) at Quarry Park. Give it a few years and it may reach the "OMG" stage.

I haven't seen much of it in eastern Princeton yet, but we'd be smart to keep an eye out and remove it before the berries mature.

Otherwise, sunny edges everywhere will look like these hapless flowering dogwoods, planted at Princeton Battlefield in 1976 for the nation's bicentenial, and now struggling to survive beneath a spreading blanket of porcelainberry.

Note: You can help liberate the dogwoods from the porcelainberry and other vines on Saturday, April 1 at 1pm. I've been collaborating with the Princeton Battlefield Society on invasive species work for the past several years, and will be leading a group to preserve the dogwoods that line the field on the north side of Mercer Street.

Another group of volunteers will be continuing the multi-year effort to reduce the bamboo clones near the Clark House, which we're actually having considerable success without herbicide. 

For purposes of identification, here are a couple closeups of porcelainberry. The berries are distinctive, with different shades of blue, red and white.

The leaves are easily confused with wild grape. This photo shows how variable is the shape.

I hope everyone's having a happy National Invasive Species Awareness Week. We'll end with a short Q and A:

• Are all nonnative plants invasive? No. Nonnative refers to origin. Invasive refers to behavior.
• Why are invasive plants invasive? Oftentimes, it's because the native insects/deer, etc don't eat them, giving them a competitive advantage. To regain the balance we lost by introducing species that evolved elsewhere, people end up having to be the herbivores, wielding saws and loppers.
• One nice thing about invasives? They get us out in the woods for workdays.