Sunday, November 27, 2022

The Blob That Swallowed Our Nature Walk

I'd been watching the weather for Sunday all week. It was almost comic how a big pile of predicted rain sat centered over the exact timeframe for the scheduled nature walk at Herrontown Woods--a mountain of rain rising conspicuously, incongruously, out of a prairie of sunny weather stretching into the distance on either side.

The consistency of the weather prediction, which showed the blob sitting in exactly the same Sunday time slot for five days straight, and which ultimately proved accurate, surely represents a triumph for meteorology.  

Astute readers will note a distinct resemblance between the blob of rain that swallowed our nature walk and the drawing of a boa constrictor that had swallowed an elephant in The Little Prince. 

Finally, we bailed, and rescheduled the walk for a week later.  

Wednesday, November 23, 2022

Nature Walk at Herrontown Woods, Sunday, Nov. 27, 1-3pm

A nature walk is planned for this Thanksgiving weekend, on Sunday, Nov. 27, from 1-3pm. If the weather looks iffy, check the events page of the website for an update. 

We'll meet at the Herrontown Woods parking lot at 600 Snowden Lane, across Snowden from the Smoyer Park entrance. Sturdy shoes are a good idea. Maps at this link.

The photo is of a pokeweed that came late to the fall color party.

Saturday, November 12, 2022

Solarizing a Princeton High School Detention Basin

Earlier this fall, I was passing by Princeton High School on Walnut Street when I saw something I'd never seen before: 

a whole field covered with plastic. The field, next to the tennis courts and a parking lot, is actually a stormwater detention basin that the school wants to replant as native meadow. But before planting, they need to kill the existing turfgrass. 

I had contacted the schoolboard members on the Operations committee a number of times over the past year, promoting the meadow idea and encouraged them to contact a federal agency called Partners for Fish and Wildlife. Over the years, I had worked with Partners to convert, at no cost, a number of detention basins in town to native meadow--at Farmview Fields, Smoyer Park, Greenway Meadows, and even at the Princeton High School ecolab just down Walnut Street. 

Instead, the school hired at some expense an outside contractor to do the conversion. The plastic is probably a very plasticky attempt to avoid the use of herbicide. If you place clear plastic over grass, the heat from the sun gets trapped under the plastic. Like a greenhouse, or the earth's atmosphere, or the windows of a car parked in the summer sun, the clear plastic is transparent for light but opaque for heat. The sunlight travels through the plastic, hits the ground, turns into heat, and the plastic keeps the heat from escaping. Trapping solar heat to kill the grass is called solarization. I had accidentally done something similar when I laid a vinyl floormat on the grass next to the curb in the hopes someone else would find it useful. No one took it, and the grass under the mat was killed, leaving a brown spot for the rest of the summer.

This PHS environmental science teacher is one of several using this detention basin as well as the ecolab to teach about stormwater issues and habitats. 

Unfortunately, the plastic was installed late in the summer, as the sun's power was waning. When the plastic was removed this week, the results were less than impressive. A deep-rooted weed called plantain remains particularly abundant. 

It would be interesting to find out why herbicides were not used. The school may well have banned the use of herbicides when school is in session, but that doesn't preclude the use after hours or on weekends. Herbicides get a bad reputation for being heavily used to impose sterile lawns in suburbia, or on farms to eliminate every last weed, including milkweed. But they can also be used, in a targeted, minimalist, medicinal way, to kill invasive weeds that would otherwise be too difficult to control physically. We manage toxicity in our own bodies, taking only enough medicine to achieve a beneficial effect. Banning herbicides brings the comfort of absolutism, and makes people feel they're being green, all the while handicapping those who are actually doing the work to restore native diversity to the landscape. 

We'll see how the project goes. Not sure what happened to all of that plastic.

Friday, November 11, 2022

What's Eating Local Viburnums?

Each time I see a native arrowwood Viburnum growing in the woods, I take a closer look. There's a viburnum leaf beetle--a nonnative species introduced from Europe--that showed up in Princeton about a decade ago. On a visit to Pittsburgh years back, I saw native Viburnums totally skeletonized by the insect, and worried about the fate of our own Viburnums in NJ. 

I've posted about this insect pest in the past. Suffice it here to say that among the various species of Viburnum in NJ, the arrowwood Viburnum (V. dentatum) is the most vulnerable. The nightmare scenario would be for the leaf beetle to defoliate all arrowwood Viburnums, then move on to decimate the next most vulnerable species.

Preferring wet ground, blooming profusely even in the shade, the Viburnum dentatum is not as common in the woods as the blackhaw Viburnum, or the highly invasive Linden Viburnum. The last couple years, I didn't notice much insect damage. This year, observations are mixed. Some shrubs in Herrontown Woods were badly eaten, 

while an arrowwood across town in Rogers Refuge showed no damage at all. 

Hopefully, the total stripping of leaves that I witnessed in Pittsburgh will prove to have been an exception, and natural predators and diseases will keep the Viburnum leaf beetle in check. Worth keeping an eye on in coming years.

Nature at the Princeton Battlefield

(Thanks to those who commented. Scroll down for an update.)
As a lover of both nature and history, I experience the Princeton Battlefield differently than most. There's gratitude for its preservation, along with some grieving for the way the land is managed. Nature here is pushed to the fringes, as if to replicate a giant ballfield. But the battle took place on a working farm, not an athletic field. 

The Clark House has been restored, its 18th century charms highly valued. So why would the landscape not be similarly treated? In the winter of 1777, the soldiers would have been treading through corn stubble, or pasture, or an orchard. 

One answer would be that visitors and re-enactors benefit from a clean surface. The question then would be how much to mow and where, so that people could enjoy a lawn, but also have areas that evoke more a feeling of the 18th century. 

As I walk across the field, I feel a sense of space more than place. Perhaps if I tried I could feel grandeur, or solemnity. Graveyards are mowed, after all. A big sky and a big field help us to understand that something big happened here, when a nation was being born, its future stretching far off towards the horizon. Maybe the landscape works in some spiritual way to evoke freedom and possibility. But as I walk these hallowed grounds, I'm also feeling a sense of a long ways to go before reaching anything interesting. Okay. Perhaps that long trudge could generate some appreciation for the long overnight march of Washington's amateur army from Trenton to Princeton. 

One tree stands in the middle of the giant lawn, an offspring of the great Mercer Oak that had witnessed the battle and lived through two more centuries before falling to a windstorm in 2000. Trees growing at the time of a great battle are called witness trees. The soldiers who fought that pivotal battle are long gone, but centuries later a tree, especially the long-lived white oak, could still claim "I was there!"

The offspring was donated by Louise Morse, spouse of Marston Morse, a mathematician who Oswald Veblen helped bring to the nearby Institute for Advanced Study in the 1930s. It was Veblen's initiative to acquire the 600+ acres behind the Battlefield that later became the Institute Woods.

The sign tells the story of the white oak and General Mercer. What I've come to look at, though, is not the highly symbolic tree but a thin sliver of golden brown in the distance. 
Beyond the lawn, towards the back of the Battlefield, is a meadow that is mowed once a year. For some reason they mowed the edge of it this fall but have left the rest, perhaps as winter cover for wildlife.
Taking a closer look, I'm surprised to see that, among the blackberries and prairie grasses, goldenrods and asters, are myriad sassafras sprouts, most of them bright orange this time of year. The meadow is a giant clone of sassafras--one root system with ten thousand heads. Can't say I've ever seen that before. 

To the left of the field is a bedraggled woods, dominated by the skeletons of ash trees killed by the introduced Emerald ash borer. A heroic American tree species silently meets its demise.

Behind the Clark House, and also across Mercer Street to the left of the pillars, more signs of introduced invasive species abound. Rampant invasive porcelainberry is stifling the 1976 bicentennial plantings--flowering dogwoods and daffodils around the edge of the field. As is typical of the landscapes we daily tread, the Princeton Battlefield invests in mowing the grass, while leaving the unmowed areas untended and overrun. Each year the Sierra Club organizes a spirited volunteer day to battle against bamboo near the Clark House. In the past, I would lead a group to cut the aggressive porcelainberry vines off of the bicentennial flowering dogwoods, but it's hard to make lasting progress when unsupported by the state agency that views grounds maintenance of this state park as "mow and go." Now all I do is make annual visits to snuff out a small infestation of mile-a-minute I spotted some years back on the Battlefield grounds.

Surely the soldiers who fought here knew their plants better than most people do today, and would feel disoriented by today's massive lawn surrounded by alien weeds. If I were to envision a battlefield landscape that sought to provide a more historically authentic botanical and horticultural context, I'd imagine some portion of the massive lawn being given over to the sort of landscape the battle was actually fought upon--pasture, orchard, corn field, whatever research shows to have been likely at the time. Along the edges would be native forest rather than tangles of kudzu-like nonnative vines. 

According to its mission statement, the Princeton Battlefield Society seeks to "restore the lands and cultural landscape." Maybe once other admirable goals are achieved, someone in the group will get interested in showing people an authentic 1777 landscape, and get the state parks department to help in the effort.  

To acquire, protect, preserve, and restore
the lands and cultural landscape related
to the Battle of Princeton of 1777;

To enlarge and improve the
Princeton Battlefield State Park;

To educate the public about the Battle
of Princeton, the Ten Crucial Days,
and the American Revolution.

Update, Dec. 23, 2022 : It's not hard to find accounts of the chronic underfunding of maintenance for NJ's state park system. This cuts both ways for Princeton Battlefield State Park. It explains why invasive species run rampant along the fringes of the park, but doesn't explain the large investment in mowing. One could have a mowed area around the house and for the areas of the land used for re-enactments and other events, and for visitors to explore the park (we used to fly kites there). Surely that still leaves large areas that could be managed for meadow. 

Nearby the Institute for Advanced Study grounds provide an example of large areas requiring only an annual mowing. 

Ribbons of mowed grass through meadow at the Battlefield would not only reduce mowing but also invite visitors to explore the full extent of the park. Walking across a vast lawn gives little sense of progress, departure, or arrival, and thus doesn't encourage exploration the way a mowed path does. 

The current management, in which nature is either suppressed by mowing or neglected along the fringes, does not reflect the view of nature held by the battle's greatest hero. George Washington was, among many things, a farmer. He believed plants were so important to a nation's future that he "had a dream of a national botanic garden and was instrumental in establishing one on the National Mall in 1820." 

In our era, when most people suffer from plant blindness, it must seem incongruous that the United States Botanic Garden is located immediately adjacent to the U.S. Capitol building. Plant blindness, according to the botanists who coined the term, "results in a chronic inability to recognize the importance of plants in the biosphere and in human affairs."

With this in mind, some rethinking of how vegetation is managed at the Princeton Battlefield could add to the visitor's experience, and shift some funds from mindless mowing to a mindful restoration of a more historically authentic landscape.

Spring Blooms in November

After a batch of 70 degree November days, look closely and you'll see the almond trees blooming along Walnut Street near the middle school. Some of these warm fall days are pleasurable. On others, the heat feels somehow suffocating, ovenlike. Our bodies are comfortable, our minds less so, knowing that the radical changes afoot on planet earth are increasingly turning the skies and seas into eternal enemies. As is typical at our current stage in the overheating of the planet, the abnormal weather will pass. We need only wait a few days for the weather to snap back into something more normal, chilly but reassuring.