Late May Sightings in Herrontown Woods and Elsewhere

A runner named Nikolas who moved to town less than a year ago and, because he has considerable curiosity and runs rather than walks, already knows the area trails better than most of us, asked me what these are. He's been seeing them along paths in many places. They are the tips of tulip tree branches--a tree that grows to giant size and has distinctively shaped leaves and tulip-shaped flowers. It's sometimes called tulip poplar, and has a poplaresque look to it, but is actually in the ancient magnolia family. For some reason, I've never been very curious about why the tips of tulip trees end up on the ground this time of year, but Nikolas was. So I looked it up, and found out that squirrels bite off the tips, then drink the spring flow of sap from the cut stem as if it were a straw. No plastic straws for a squirrel, and it must be exciting to quench one's thirst while teetering at the end of a branch, 70 feet above ground. There's also a scale insect that can suck the sap from a tulip tree, then drops its aphid-like honeydew on the ground below, like a sticky rain. Fortunately, that's according to the internet rather than experience.

Very rarely, Jack in the Pulpits have this prominent venation. One nursery sells it as "Starburst."

Yellow star grass, seen now and then along trails, looks like a grass but isn't, in much the same way that blue-eyed grass looks like a grass but is actually an iris. Sedges and rushes are also plants that look like grasses but are not. Botany rewards those who take a closer look at things.

Wood briars have the latin name of Smilax and tend to have thorns and arching veins in the leaves, and grow up and over things. This one is less frequently encountered, has no thorns and supports its own minimal vertical ambitions. Called Smilax herbacea, apparently because it's more herb-like, its common name is carrion flower, named for the alluring aroma of its flowers, which I have yet to sample. Hinting at its preference for wet ground is all the jewelweed and stiltgrass seen rising from the ground below it in this photo.

Bladder sedge is one of the sedges with interestingly shaped seedheads that make up for the lack of color.

Have seen tiger beetles a couple times in Herrontown Woods this spring. They are speedy predators.

I happened to take a peek behind an ugly strip mall in Princeton Junction and found that where the expanse of asphalt ended, an amazing ecosystem began, filled with blueberries and sweet pepperbush and expanses of ostrich fern, growing beneath oaks and even a American chestnut that was hanging on. One could grieve for what was buried beneath the asphalt sprawl, or be astonished at what has managed to survive.

People often ask what the white flower is that grows a couple feet high and looks pretty but a little weedy. Daisy fleabane. (Betty Horn reminds me that there are a couple species of fleabane.)

This is what happens when you plant daffodils in spring rather than in the fall. They bloom in May and June.

Keena sent me this photo of a puffy golfball-sized growth on a white oak at the entrance to botanical garden taking shape next to the main parking lot for Herrontown Woods.

Turned out to be the tree's creative response to the wool sower gall wasp, which lays its eggs on oaks in the spring. The wasp "sows" its progeny, and ends up growing something wool-like in the process.

Red buckeyes are good to plant under powerlines, since they don't get very big, and would be an excellent tree to plant south of a house that has solar panels. People think that we must choose between trees and solar panels. No, just plant trees that don't grow tall, and one gets the carbon sequestration and cooling action of the tree plus the power generation and roof shading of the panels. That's what we call a "win-win."

The Very Dramatic Caterpillar Eating Wild Blueberry Bushes

Before I saw the blueberries, I saw the caterpillars eating the blueberry bushes. They were distinctive in the braiding of their bodies into a cluster on the stem. I snapped a photo of their distinctive black heads, yellow necks, and striped bodies, and must have brushed against the bush, because when I looked at them again, surprise!

They had all contracted their bodies into a dramatic pose that completely hid their heads, as if they were the caterpillar world's equivalent of a synchronized swim team. What's the logic here? Look down and away and the potential threat will disappear? Seems human, somehow--a caterpillar's artistic pose to symbolize society's head-in-the-sand response to climate change.

A nearby bush had been stripped of leaves but still had a few blueberries.

While highbush blueberry bushes tend to be solitary, the lowbush blueberries I have seen in woodlands, whether in North Carolina, on top of New Jersey's Mount Tammany, or in Princeton's Herrontown Woods grow clustered in colonies on a hillside.

These heavily shaded patches and the measly crop they bear seem to me stunted remnants of a past glory, when periodic fires would sweep through, thinning the canopy and setting the stage for a burst of new growth from the resilient roots of the blueberries, which then prospered in the partial shade of the scattered trees. Thick bark and decay-resistant leaves are common traits of trees that are adapted to periodic fire. Oaks exhibit these traits in Princeton, their leaves persisting on the ground as fuel for fires that no longer come.

The most dramatic example of the distortion caused by fire exclusion that I've witnessed was in a woodlot preserved as part of Bennett Place, a Civil War site in Durham, NC where the war's largest surrender took place. In the past, trains passing close by would throw sparks, causing low-burning fires to sweep through the woodland, promoting the growth of fire-adapted post oaks and shortleaf pine. I like to call these rejuvenating events "mildfires"--the relatively tame wildness of a healthy nature--in contrast to the destructive wildfires we're used to hearing about in the news. The woodland--perhaps more like a savanna--was a favorite place for Duke University botanists to find a rich understory of wildflowers prospering in the open shade. As they remarked on this or that rare species of wildflower, they must have sampled the berries from the broad patches of blueberries that persist there. As trains have become less sparky, and people more fire-averse, the less fire-resistant, fast-growing trees like willow oaks have grown up, while the deepening shade and the accumulation of unburned pine needles have stifled the wildflowers. The once-thriving "fire-climax" ecosystem is begging for a fire that never comes, as the old trees slowly succumb.

Though the exclusion of periodic fire has also made Princeton's woodlands less natural, we can see in the caterpillars' partial munching--some shrubs eaten, some not--the persistence of another aspect of balance in nature, worked out over millenia of coevolution. No species can survive long if it wipes out its food source. Long-term stability thrives on balance. New species introduced from other continents lack these elaborate checks and balances. Stiltgrass smothers large swaths of Princeton's preserves because nothing eats it. Our forests have suffered a series of shocks, from chestnut blight in the 1920s, gypsy moths in the 1970s, and now the emerald ash borer--all from introduced species that lacked the checks and balances that evolve over time.

The common name for our very dramatic caterpillar, "contracted datana," is hardly a common name given how few of us have heard of it, and is merely an adaptation of its latin name, Datana contracta.  Come to think of it, the heads of the caterpillar look a lot like blueberries. Their collective ducking seems to be saying to a hungry predator, "Please move along, no food here!"

Hicans and Other Useful Trees at Princeton Battlefield

When people think of trees at the Battlefield, the first and perhaps only tree that comes to mind is the Mercer Oak, which these days is Mercer Oak II, an offspring of the original, donated by Louise Morse, a remarkable woman who spent much of her long life advocating for good causes. She was wife of Marston Morse, one of the first generation of mathematics faculty at the Institute for Advanced Study.

The Mercer Oak plays an ambassadorial role for the Battlefield, a star, positioned near the road while other less heralded trees serve more prosaic functions further back.

The young oak, a teenager or perhaps a young adult at this point, is flourishing after donating much of its foliage to the insect world two years ago.

It's appropriate that the oak came from Mrs. Morse, because she herself was extraordinarily long lived, reaching 105, and, like an oak that gives of its foliage to 100s of species of insects, gave generously of her time to such causes as Stuart School and civil rights.

Closer to the house are less known but more edible trees. Beneath this one is a bumper crop of pecans, but the tree is not fully a pecan tree.

It is, instead, a hican. Like a mythical beast whose body doesn't match the head, it has the base of a hickory and the top of a pecan. You can see the change in bark from rough to smooth about six feet up on the trunk.

Chinese chestnuts, too, are having a banner year.

In front of the house, a native chestnut we planted (15/16th American), is hanging in there, though its trunk is nearly girdled by the blight.

It, too, is laden with chestnuts.

Another native chestnut on the other side of Mercer Street had looked to be flourishing, but succumbed suddenly this year. The disease does not kill the root, however, so multiple sprouts rise from the base, to be browsed on by deer.

Undeterred, Bill Sachs and I added protection to some more recently planted native chestnuts that were getting beat up by the mowers. Such a perilous world these trees enter into.

Along the field edge, the bicentennial dogwoods planted in 1976 are benefitting from the work volunteers did this spring to keep the porcelainberry vines off of them.

This shot from underneath the trees shows the wave of porcelainberry that wasn't quite able to reach the lower branches of the dogwoods.

The less shading from the vines, the more berries the dogwoods can produce to fuel the fall bird migration.

This would be the fate of the dogwoods if we didn't help them out--completely enveloped by the porcelainberry.

Two of the classic inedible trees to be found around historic homes are horsechestnuts and black locust. Clark House lacks the horsechestnut but has several grand black locusts. Black locusts provided extraordinarily rot-resistant wood for fenceposts, abundant flowers for honey, and some say they help steer lightning strikes away from the house.

With Trees, Looks Can Be Deceiving

Here's a tree that looks dead, but is probably okay. It's a horse chestnut--a species long associated with historic houses, and like many horse chestnuts lost its leaves early, perhaps due to a leaf blotch fungus. Though planted in front of a newer home, its history is connected to the 18th century house around the corner, once lived in by Joseph Stockton and, reportedly, an occasional sleeping pad for Thomas Jefferson.

And here's a recently planted ash tree a few blocks away at the Westminster parking lot, looking good but not long for the world, due to Princeton's ongoing Emerald Ash Borer invasion. When I saw that ash trees were planted as part of the parking lot expansion, I urged Westminster to get the designers to pay for replacements that would actually live long enough to shade the cars parked beneath them. Hoping I'm wrong about it all, but any followup photo a few years from now will likely show a gap where this tree now stands.

PawPaw Patches Proliferate in Princeton

My friend Stan, who has a knack for collecting and growing out seed of local fruit trees, gave me about twenty pawpaws (Asimina triloba) he grew from local populations of this remarkable native species. Though adapted to the north, the pawpaw bears a fruit reminiscent of mango. Hard to store and ship, the fruit has proven hard to turn into a cash crop, so it remains at the margins of our diets and awareness.

I delivered three to Mountain Lakes, for planting there, then called up my friend and author-of-note Clifford Zink over at Harrison Street Park, to see about starting a pawpaw patch over there.

Last month, we planted three in a swale that receives water from a nearby parking lot--a good urban version of the floodplains that are the pawpaw's preferred habitat.

Around the same time, Bill Sachs gave me some white cedars and hemlocks he'd grown in his backyard. Bill has been leading efforts in town to bring back the native chestnut and butternut. Since white cedars are adapted to swamps, two of them ended up in the Princeton High School ecolab wetland, thanks to environmental science teacher Tim Anderson and his students.

Most of the pawpaws are being saved for planting a pawpaw patch out at the Veblen House site, part of a PawPaw Patch Planting Party, public invited, tentatively scheduled for the first weekend of the new year, El Nino weather permitting.

(Other pawpaw posts can be found by typing pawpaw into the search box at the top of this website.)

Nature Trail: From the All Saints Tract to Herrontown Woods

One of the entryways into the long corridor of preserved land called Princeton Ridge East, including Herrontown Woods, begins on a bikeway that heads up past Princeton Charter School on Bunn Drive. You can enjoy this asphalt bikeway's smoothness, and note that the trees are far enough away that their roots haven't made ridges in the pavement.

For anyone who's curious, a little ways up, across from the water tower, just in from the road, a native chestnut tree is hanging on in deep shade. It was discovered by arborist Bob Wells while he was inventorying Princeton's street trees, and is the only wild native chestnut that we know to exist in town.

Up the hill are the new Copperwood apartments. Though some grand old beech and oak trees were sacrificed to build it, the developer heeded strong resistance from local environmental groups and, rather than spread the allowed units out across the property, he clustered the apartments so that some 20 acres of ridge forest could be preserved.

Look down and to the right from the Copperwood entrance and you'll see a long straight trail extending into the woods. That's the pathway leading through land preserved by the municipality, county and environmental groups, with particularly significant effort put forth by DR Greenway and the Friends of Princeton Open Space.

Just in on the left as you walk down the trail is a large berm that holds back stormwater from Princeton Community Village and Copperwood. There's a slow drama underway on the berm. Woody plants aren't allowed to grow there, so the berm's floristic destiny might be native wildflowers like these late-flowering thoroughworts,

but Chinese bushclover is starting to get a foothold. It was introduced into the U.S. for use in erosion control, and promoted as offering abundant seed for wildlife. But the seeds proved undigestible, and the species has proved extremely invasive, outcompeting native wildflowers and creating inedible monocultures. With a few hours' work, the Chinese bushclover could probably be eliminated from this berm, but management doesn't tend to be proactive, which means the species is likely to increase in number until it's too intimidating to deal with. Where's that Friends of the Berm group when we need them?

Unless you're going to the imagined Friends of the Berm workday to remove Chinese bushclover, continue down the straight and narrow until you encounter one of two trail signs on the left.

These are DR Greenway signs, as part of their followup to preserving the All Saints tract. Down the hill from the preserved property is the All Saints Church itself, which is also home to the Princeton Learning Cooperative, for teens who seek an alternative to a traditional middle or high school education. Our Friends of Herrontown Woods group has partnered with them on nature walks.

Sometimes, it takes a village to maintain even a small sign like this. A resident of Copperwood told our Friends of Herrontown Woods group that he and his wife couldn't find the signs leading to Herrontown Woods. We went looking for the map, found it had disappeared, then told DR Greenway staff, who replaced it. Such is the fabric of connection that keeps Princeton's open space navigable.

Earlier in the fall, I led a walk through the All Saints tract for local digital technology educator John LeMasney and some of his friends. Along with all the beautiful moss-covered boulders of the ridge, we encountered a white oak tree that cleaved but did not break in one of the windstorms of recent years.

Here, Peter Abrams, designer of "B Homes" made of used materials like pallets, and John seek out the right angle for photographing this angled tree.

Where All Saints transitions into Herrontown Woods, we took a look at an umbrella magnolia tree, which may be the only example of this species along the Princeton ridge. The Institute Woods hosts a larger population.

These trails can also be accessed from the Herrontown Woods parking lot, down the street across from the entry to Smoyer Park (where another friend of John's showed off a manual chain saw, which could be useful for invasive shrub removal), and from Journey's End Lane, off of Terhune Road.

Emerald Ash Borer in Princeton

Here's a stock photo of the recently arrived insect that will kill (there must be a better word) Princeton's most numerous tree species over the next decade. White ash, green ash, and the much less common black ash--all are vulnerable. The photo shows an ash tree with characteristic "D"-shaped exit holes. It will take a lot more than a penny to deal with the consequences of this diminutive beetle's appetite. I'll expand below, but I sent the quick read version out in a mass email that was then quoted in an informative article in the Town Topics:

"Emerald Ash Borer (EAB) was found in a trap set by the town arborist out along River Road. This small green insect, accidentally introduced to our continent from Asia, probably in wooden packing crates, has been spreading outward from its original introduction in the Detroit area, killing 100s of millions of ash trees. The insect will spread across Princeton over the next few years, eventually affecting all ash trees that haven't been treated. Highly valued ashes can be injected in springtime with an insecticide. The treatment can provide protection for several years. Of the various chemicals available, I've heard the most praise go to Arbor Mectin. Tree-Age has a similar formulation."

The Next Fifteen Years

So, what happens now, and what can we do about it? Princeton's arborist, Lorraine Konopka, sees this slowly evolving catastrophe following a fifteen year arc. In the first five years, EAB will spread around town, building up its numbers with each new generation. Symptoms are slow to manifest, but in various ash trees we'll start seeing dieback starting at the top of the crown and working its way down. Many ash trees are already suffering from ash decline, notably a disease called ash yellows, making it even harder to know for certain when EAB has invaded a particular tree. Homeowners will be forced to choose between spending hundreds of dollars every few years to treat favorite ash trees with systemic insecticide, or spending thousands of dollars later on to remove their dying ash trees before they become brittle and dangerous. The five years that follow will be marked by radical dieoff, both in town and in our nature preserves. Some woodlands where ash trees dominate will be decimated. We'll see otherwise green hillsides dotted with skeletonized remains of ashes. The five years after that, more or less, will see the last untreated ash trees succumb. The population of EAB will drop dramatically, but protected trees will continue needing new injections of insecticide, though potentially less frequently. Ash trees will still be found in nature preserves, but likely get attacked as they grow towards maturity. More on the aftermath at this post, written after a visit to Ann Arbor, MI.

Life Cycle

According to an EmeraldAshBorer.info webpage, the Emerald Ash Borer hatches into an adult in May and June (coincidentally, emergence is said to begin around the time that black locusts bloom), flies to new areas and mates in June and July, then lays its eggs in August. The larvae feed just inside the bark in the fall, then overwinter as pre-pupae before hatching into a new generation of adults the next spring.

So it's not surprising that the first confirmed sighting of an emerald ash borer in Princeton happened in late July, when one was found in a trap placed near River Road by the town arborist. Previous documentations in the area were in Bridgewater, West Windsor and other towns.

Treatment to Protect Ash Trees

Homeowners will need to decide, over the next year or two, which if any ash trees they wish to treat. The expense of recurrent treatments, and the ongoing benefits of the tree, need to be weighed against the cost of removal. This definitive article recommends treatment of trees if EAB has been found within 10-15 miles, which is now the case for Princeton. Treatment is most effective in the spring, between mid-May and mid-June, just after the tree leafs out. The article confirms the superior performance of emamectin benzoate, the active ingredient in Arbor Mectin and TreeAge. This insecticide may be more expensive than others like imidichloprid, but lasts longer and has a higher success rate. For more on my research on this issue, scroll down at this link to "How to save specimen ash trees".

Natural Predators of EAB

Woodpeckers are said to eat 80% of the EAB, but that's not enough to stop it. There are native parasitic wasps that also prey on EAB, but not in sufficient numbers. Some parasitic wasps species from the EAB's native range in Asia are being introduced (hopefully with a great deal of prior testing to show they won't prey on our native insect species), but I doubt they will influence the arc of Princeton's infestation over the next decade.

An article in the NY Times discusses techniques to stimulate the defense systems of ash trees so that the tree itself will manufacture sufficient chemical defenses to ward off EAB, but again, any practical use is highly speculative.

What's a Dead Ash Good For?

Strangely, there seems to have been no planning at any governmental level to at least put the coming surge in dead wood to use. Talk of sustainability and the opposition to fracking and natural gas pipelines are weakened if we ignore local sources of renewable energy. Lacking wind, we need to turn to sunlight. Solar panels, now essentially free to install, are an obvious option, but for some reason wood is being ignored. Europe has clean incinerators that generate energy from wood chips. Ann Arbor trucked its ash trees to an energy-generating facility in Flint. Unlike the carbon from fossil fuels, carbon from trees comes from the atmosphere, not from underground, so there is no net increase in above-ground carbon when wood is burned. Composting requires considerable fossil fuel for turning and transporting the compost, and decomposition releases as much carbon as burning.

In addition, the EAB invasion is coming just as Princeton's collection of loose yardwaste is being expanded. There is no effective incentive yet in place for homeowners to trim their dependence on this costly program, and the addition of 1000s of ash trees to this already over-burdened collection service could overwhelm the capacities of the public works department and local composting sites.

Possibly relevant, the state compiled this list of "Forest Industry Professionals Accepting Ash Trees".

Previous Posts

The Emerald Ash Borer's arrival in Princeton had been long anticipated. Some fifteen posts on this blog mention it, dating back to April, 2010, when I wrote,

"In Princeton, we will over the next decade likely witness a dieoff approaching the scale of the chestnut and elm dieoffs of the 20th century, as the emerald ash borer, which hitch-hiked to Michigan from Asia in wooden packing crates, continues its spread eastward. There will, in other words, be a lot of gaps in the canopy for the chestnut to claim, if its return is successful." 

That last part, about a resurgent American chestnut filling the gaps as we lose our ashes to the Emerald Ash Borer (EAB), as the previous post about chestnuts shows, was a nice concept but overly optimistic. Here's a particularly extensive post on EAB, in which I included notes from a phone call with the division chief of Forest Pest Management in Pennsylvania, where they've been dealing with EAB for years.

Native Chestnut Update

While the discovery of Emerald Ash Borer in Princeton several weeks ago cast a big shadow on Princeton's most numerous tree, there's another shadow, growing larger every year, that's reason for hope. That would be the shadow behind this native chestnut tree growing at the Textile Research Institute (TRI) in Princeton. Planted just five years ago, it's now fifteen feet tall, well on its way to taking its place among the oaks towering behind it.

The protective collar around its trunk is beginning to unzip as the tree gets too big for its britches.

This marks the first year it has bloomed, though there may not be any nuts for lack of pollen from other trees. In future years, a less precocious companion planted nearby may catch up and provide that pollen.

These chestnuts, which are really 15/16th native, with some asian genes mixed in to aid in resisting the chestnut blight that laid this species low a century ago, were planted by Bill Sachs, a local nut tree expert who has planted chestnuts and butternuts in a number of locations in town. Butternut is another native tree much reduced in numbers due to an introduced disease.

Below is Bill's status report, from an email. It shows how much persistence and resourcefulness is needed to bring back a species, with a touch of serendipity now and then:

"Yes, I know the one chestnut at TRI flowered this year but there may be no nuts for lack of a pollinator. That tree was two year-old bare rooted stock when planted in 2010. Pretty precocious. Same generation as the ones we planted at Mountain Lakes (there are no healthy survivors left there) and on the Princeton Battlefield (two survivors, one of which has blight). This fall and spring, we may try to inoculate the trees that have blight with the virus that causes hypovirulence. 

There are three planted butternuts at TRI, all pretty close to one another. Two of them have been surrounded by blackberries and other brambles that need to be cleared. Will do that this fall… may need to rent a brush cutter.

Also, discovered a ‘new’ native butternut at ML with a few nuts on it. Been walking past it for years and this is the first time I noticed it because I happened to be looking up into the surrounding crowns to assess the health of the ash trees along the trail."

Bill