Champion Brearley Oak in its Glory

There's a magnificent black oak growing, growing, growing in an unlikely place along Princeton Pike. Like the Mercer Oak, Jr. just up the road at the Princeton Battlefield, this oak too is of such distinction that it has its own corral. Driving by recently, I couldn't resist pulling over into the new Bristol-Myers Squibb parking lot and walking down to take a closer look at how it's doing. This champion tree--so-called because it's by far the largest in the state--is thriving, standing like royalty, master of its domain, with full access to sunlight all around and the soil all below.

The crown overflows its 100 foot diameter corral. Each of its millions of leaves is glossy and beautifully sculpted, the acorns small, as if this giant tree were compensating for the lone osage orange tree up the way about half a mile, barely a quarter of the black oak's height but with softball-sized fruits.

You can see the location of the Brearley Oak marked on this map, just above the hyphen in Bristol-Myers Squibb, close to Princeton Pike. The tree stands at the southernmost point in the Lawrenceville Hopewell Trail--a trail large enough to have its own nonprofit and website.

Nearby, to the east and north, is Brearley House and a park named after a great meadow from colonial and Indian times, and which the oak may have been witness to. That meadow was likely natural in part, but also managed at first by American Indians, who tended to burn the landscape, the better to attract game with the nutrient-rich growth that sprouted in the fire's aftermath.

There was a time when an oak this massive, with 20+ foot circumference, and perhaps 80 feet tall, would have been the rule, not the exception, when much of America was managed by American Indians, with the help of fire. The oaks have fire resistant bark and decay-resistant leaves adapted to remain on the ground as fuel. Then, when a low, mild fire started by lightning or people comes along, the leaves carry the fire across the ground, which in turn kills the oak's thin-barked competitors but not the oak.

The red dots on the map below, from Charles Mann's 1491, indicate areas managed by American Indians with fire. There are lots of dots shown in what is now NJ.

Red dots are areas managed by American Indians with fire (from the book, 1491)

In colonial and pre-colonial times, an oak like this would have had a rich understory of wildflowers and grasses, adapted to the ever shifting patterns of sun and shade.

One of the limbs is so long that it's  supported by a post.

And a lightning rod is attached on either side.

I'd love to go there sometime with a group of people. We'd recline on lawnchairs and gaze upward, tracing with our eyes the limbs' ascent towards the sky. A tree is like a city, with thoroughfares and sidestreets and cul de sacs of leaves. It is a solid built of air, some of which it breathed in before we were a nation.

Ignoring busy Princeton Pike and the sterile corporate lawns that surround it, this black oak soaks up the sun, drinks deeply from below, dreaming green dreams of mighty landscapes past.

A Turtle's Narrow Escape

If a truck passed over me while I was crossing the road, I'd probably pee in my shell, too. That's what it looks like happened here, having encountered the turtle on that small university road on the West Windsor side of Lake Carnegie, just after a truck had passed over it.

Just one more insult for a turtle to endure. It refused to tell me which side of the road it preferred to be on, so I put it on the canal side, where the habitat is, and hoped for the best.

Duck Takes Nature Walk at Herrontown Woods

Young ducks are great for taking on nature hikes, imprinted as they are on their human caretaker. We had one come hiking up the trail recently to the Veblen House grounds while we were working on preparation for this Sunday's Veblen birthday gathering (come if you can).

A writeup on the duck, a magpie, is at this link.

Non-Native Shrubs Shade Out Spring Wildflowers

This time of year, you can tell with one glance how many non-native shrubs are growing in a local woodland. Non-natives like privet, winged euonymus, and bush honeysuckle leaf out earlier than most native shrubs, reflective of their having evolved in a different climate from our own. Many of our woodlands are now thick with these non-native shrubs, and their early leafing out has ecological consequences. The spring ephemeral wildflowers have evolved to utilize the sunlight available during that window of time in spring when the woody plants above them are still dormant. Introduce woody plants that leaf out earlier, and the wildflowers can't store up enough energy to bloom the next year.

This problem will be exacerbated as we lose the many ash trees in our woodlands, since the nonnative shrubs will likely grow all the more densely as more sunlight reaches the understory in summertime. At Herrontown Woods, we're cutting down the non-native invasive shrubs, to allow more sunlight to reach spring wildflowers, and also to allow native shrubs a chance to thrive.

A Pretty (scary?) Snake in the Basement

Earlier this week, I received the photo below in an email entitled "Copperhead?". The email was from Robert Socolow, a distinguished physicist at Princeton University. He usually focuses on climate science, but this past weekend his focus was drawn to an unusual snake he found in his basement up on the Princeton Ridge. This particular snake subsequently met its demise, but the thought that it could be a venomous copperhead snake made him leery of spending any more quality time in his basement.

My first guess was a corn snake, but we needed more than a guess. I sent the photo to my friend Perry in Durham, NC, where I used to see copperheads now and then in my old stomping grounds along Ellerbe Creek, their heads above water, gazing upstream.  He in turn sent it to his friend and Duke University biologist, Ron Grunwald.

The answer came quickly: Eastern milk snake, nonvenomous. They're said to be fairly common. According to the wikipedia page, they are a kind of king snake that can be found in various habitats, including rocky slopes (the Princeton Ridge), and also in barns. Their presence in barns may be the reason a myth arose that they suck milk from cows, which anyone who knows snakes and cows will agree is udderly ridiculous.

Rob was relieved, but the episode begged the question: Are there venomous snakes in New Jersey? The answer to that came very fast, when up popped the website for Conserve Wildlife Federation of NJ, and a post on the northern copperhead (affectionately known among herpetologists as Agkistrodon contortrix mokasen). For anyone thinking of copperheads as a southern species, it's a surprise to learn that the northern copperhead's range actually begins north of Princeton, extending from the Sourlands up through northern NJ.

The range of the one other venomous snake in New Jersey, the timber rattlesnake, conveniently avoids Princeton, with populations both north and south. The scientific name for this snake is Crotalus horridus horridus, which seems unscientifically judgemental. 

For the curious, there's a nice-looking pamphlet of New Jersey snakes at this link. 

Thanks to Rob for sending the photo, and to Ron for the identification. Though the snake may well have been doing a fine job limiting the number of mice and camel crickets in his basement, Rob was understandably prompted nonetheless to reaffix the screen that had fallen off a drain pipe leading from his basement to the great outdoors.

A Deer's Landscape Services

Funny. I didn't remember requesting landscape services. Deer hadn't shown up in our backyard since around 2005, when the birth control experiment was still underway and the females were looking elegant and very Princetonian with those identification cards hanging from their ears. Maybe it was taking refuge from hunters, or had had enough of rutting season.

Deer are expert landscapers, trained from birth in the art of pruning. They wouldn't think of driving around town in those giant fossil fuel-consuming trucks that deploy gangs of mowers to quash nature's vertical ambitions.

Deer are too considerate to make a racket with leaf blowers. And instead of releasing a cloud of fumes to sting your nose, they leave behind discrete contributions of fertilizer. They do the landscaping for free, but have a strong independent streak, refusing to adjust their methods to an owner's wishes.

Deer are very sensitive. Even though I stood ten feet back from my bay window, I still had to freeze several times so as not to spook my subject. It's impressive how they are so observant and "in the moment"--a state of mind we too might more easily attain if we were further down the food chain.

When I stepped outside to shoo it away, it didn't flee back over the fence but instead ducked behind some shrubbery in a back corner, waiting for my next move.

Once it realized I was not a threat, but instead just another among Princeton's backyard paparazzi, it regarded me with what appeared to be disdain.

No longer feared, I went back inside without finding out from where it came into the yard.

It was interesting, though, to watch it at work, browsing maybe ten leaves of our oak-leafed hydrangia before moving on to munch some grass. Though I've heard stories of deer wiping out a gardener's favorite plants overnight, my experience is that animals generally lack a thoroughness, whether it be browsers or predators.

My theory with deer is that their alertness to the potential for attack makes a patient devouring of one shrub less adaptive than a few nibbles here and there. And if much of what they eat has some level of toxicity, browsing can help reduce the risk of consuming too much of any particular toxin at any one time. Light browsing also promotes quick recover by the plants, as long as there aren't too many deer visiting the same plant. This suggests that deer could actually be good stewards, if their population was in balance with the landscape.

Wanted: A Few Good Herbivores

If you encounter a book or article that claims that, surprise!, invasive species aren't such a big problem after all (a few were written over the past decade), you'll probably find no mention of herbivory. They'll say that invasive plants are being falsely maligned, because actually they do wonderful things, like provide berries and nectar for wildlife. But it's to the plant's advantage to have its flowers visited and its berries consumed. What the plant doesn't "want" is to be eaten, and therein lies the problem with plants that become invasive. For whatever reason, be it an invasive's chemical defenses or ingrained dietary habits, the wildlife tend not to eat them.

Nature depends on consumption to keep things in balance. We love nature for its beauty and variety, but behind the scenes there's a whole lot of mastication going on. Take away predators and the deer population explodes. Introduce a new plant that the wildlife won't eat, and there's potential for that species to make habitat less and less edible as it displaces the natives. To fill this void in consumption, people have had to play the role of herbivores. What we do at Herrontown Woods, as we cut down dense groves of winged euonymus and other nonnative invasive shrubs, is to play the role of the missing herbivores, using our loppers for teeth.

There's some pleasure in the work--pleasing vistas created, serendipitous discoveries. But all things being equal, it would really be nice if the resident wildlife could show some flexibility in food preferences and fill the void in consumption. Invasives, after all, represent a huge, untapped food source for any animal willing and able to broaden its palette.

Given how much work it would be for humans to play the role of herbivores in the forest, any evidence of wildlife gaining an appetite for invasive plants stirs some hopefulness.

For instance, an invasive honeysuckle shrub was recently found stripped of its leaves. A closer look revealed something had been hard at work, its mandibles outshining our loppers: the caterpillar of a snowberry clearwing moth, also known as the "hummingbird moth" or "flying lobster", for its capacity to hover in front of flowers as it sips their nectar. Maybe if we had more summer wildflowers for the adult moths to feed from, their caterpillars would help control the populations of bush honeysuckle in Princeton's preserves. Nice to think, anyway.

And what's this orange plant growing on a dense expanse of invasive mugwort that grows as a monoculture along the gas pipeline right of way in Herrontown Woods? Dodder is a parasitic plant with little capacity to gather energy from the sun. Instead, it wraps itself around other plants and sucks out their juices.

Usually, its impact is small, but this must have been a particularly good year, because a sizeable patch of mugwort was sucked dry.

If only we could get the dodder (genus Cuscate) to preferentially neutralize the mugwort all along the right of way, some diversity might return. Again, a nice thought and tall order.

A new invasive trying to gain a foothold in Princeton is mile-a-minute vine, with a distinctive triangular leaf, a prickly stem, and a growth habit to match its name. Another post shows how invasive this annual vine can be , on farms just outside of town. Fortunately, after weeding out a small population back in 2007, I know of only two patches currently growing in Princeton, still small enough to control and hopefully eliminate altogether.

One's at the Princeton Battlefield. This year's growth was pulled out in early summer, and when checked in late August, the patch had only managed to produce a few leaves, all of which were being very effectively munched on by a weevil intentionally introduced to the U.S. to bring this rampant new species under control.

Ah, I concluded, to control mile-a-minute vine, simply reduce the patch in early summer, leaving enough for the weevils to sustain their population on. Their appetites appeared to be sufficient to prevent any flowering or fruiting that could lead to the patch spreading elsewhere.

Nice concept, but it wasn't working at the other site, down along the driveway into Rogers Refuge, where the vine had sprung back up, flowered and fruited, undeterred by the minor nibblings of the weevil. That patch had to again be pulled out by hand.

Another discovery was the work of the Ailanthus webworm moth, which had completely defoliated a young tree of heaven near the parking lot of Herrontown Woods. The moth, like the tree, is an introduced species.

If you have flowers like boneset growing in your backyard, you may be helping the adult moths to prosper.

Here again, though, the larvae have thus far been seen only on very young trees, with larger ones largely left untouched.

These are glimmers of hope, sprinkled across Princeton. It will take some concerted mastication by as yet unnamed herbivores to stem the tide of rapidly spreading species like porcelainberry, callery pear and stiltgrass--a giant uneaten salad that grows by the year. A little salt and pepper, perhaps?

Wildflowers and People Gather By the River

What a glorious day, this past Sunday, down along the canal in Princeton. Cool, sunny weather drew people to the canal, by boat, foot and bicycle. The sounds of laughter and conversation mixed with birdsong and a generous show of summer floodplain wildflowers.

Boys returned to their Huck Finn roots,

and insects, too, gathered by the river

or bathed in the sun.

Many different species of oak have long gathered along the section of the towpath between Harrison St and Washington Rd, planted back when the university viewed the canal as an ornamental entryway to campus.

Here's white oak, with it's rounded lobes,

and possibly a post oak, with its lobes arranged in the shape of a cross.

Swamp white oak and bur oak have similar leaves, swollen towards the tips, like the bison that used to forage in the oak savannas of the midwest and south, back when mildfire could play through and refresh the landscape.

Not sure what type of oak this is.

It was a day when nature seemed to be moving towards restoring balance. The overly aggressive multiflora rose was getting a humbling dose of rose rosette disease.

One Ailanthus, at least, was being slowed down by the munchings of the caterpillars of the Ailanthus webworm moth.

The adult is the orange patterned insect in this photo.

And a honeysuckle shrub was being hampered by some sort of witch's broom growth.

Queen Anne's Lace was being pretty without taking over.

Introduced knapweeds like spotted knapweed have spread very agressively in the midwest. I've been trying to believe that this Tyrol knapweed will be relatively benign as it spreads slowly along the canal. Here, at least, it's hosting a monarch.

True, the porcelainberry was having its way in one of the openings in the canopy,

and capitalizing on a tree's demise.

Stiltgrass still lines the nature path,

and a Norway maple's dense shade was stunting growth beneath it.

Mugwort framed concrete marker, but hasn't dominated along the canal like it sometimes does in gas line right of ways.

Signs at the Harrison Street crossing warned of hydrilla, an aquatic invasive plant. None of this, however, could break the upbeat mood of a cool, sunny Sunday in late July.

Flowers from earlier in the year were quickly turning into seeds, like buttonbush

silky dogwood,

common milkweed,

One of the ornamental cherries planted by the university long ago,

pokeweed,

and tall meadow rue.

Seeing native shrubs like this elderberry trying to grow along the banks of the canal, I long ago envisioned managing the banks for native shrubs that could beautify and provide abundant wildlife food. But the banks of the canal are managed independently of the towpaths, by a different agency. As with most landscape maintenance, the workers tend to be unselective in what they cut. To preserve the view from the towpath, the bank is cut every few years--not enough time for a shrub to do much flowering and fruiting that would benefit wildlife.

Not far down the lake from Washington Rd. bridge stands the stump of a sweetgum tree once darkened each day by roosting cormorants.

Its life may have been cut short by the excess guano, or its own precarious perch on the edge of the bank. Not sure where the cormorants have gone.

Another sweetgum, with its star-shaped leaves and protruding wings on the branches, was thriving elsewhere along the trail.

Some of the wildflowers have grown to giant size with the well-spaced rains this summer. These cutleaf coneflowers are ten feet high,

as are some of the ironweeds.

The cutleaf coneflowers were the first native wildflowers I spotted ten years ago along this section of the canal, which in turn led to the state park staff reducing the mowing to once a year so these wildflowers would have a change to mature and bloom

Hollow-stemmed Joe-Pye-Weed has really prospered in the open shade of the oaks. Each year there are more patches of these attractive flowers.

Goldenrods can be distinguished by the different shapes of their flowerheads. Some have elm shaped inflorescence,

others are flatter.

Each year, the rose mallow hibiscus bloom along the shore, with lizard's tail and yellow pond lillies extending out into the Carnegie Lake waters beyond them.

It would have been a perfect day to lead what usually is an annual nature walk along the towpath. For 2017, this account will have to do.