The Color-Coded Forest--Nature's Halloween

This time of year, the forest does its own inverted version of Halloween. Rather than obscuring their identity behind costumes, the trees and shrubs reveal their inner identity. As the chlorophyll fades away, the leaves show each species' true colors, which had been there all along, hiding behind the green facade. These bold declarations make it suddenly easy to identify every bush and tree in the forest, near or far. In this photo, a small sweetgum tree shows its yellow, with Photinia behind it tending more towards brown, and the still green bush honeysuckle rising farther back. Flowering dogwood pokes in some burgundy at the top center of the photo.

Some species are tricky, varying their color depending on location. In front of the Princeton Shopping Center (no photo here), the winged euonymus shrubs lining the old gas station site turn brilliant red in full sun. Given less sunlight, as here, growing at the edge of the woods, they turn a modest pink.

In deep shade, their leaves turn white in the fall.

The native euonymus--Hearts-a-Bustin, which is currently extremely rare locally--also can turn this uncanny, ghostly white.

Very dramatic has been the Japanese maples growing next to the Veblen cottage out at Herrontown Woods, whose condition makes it seem to some a haunted house out in the forest.

The color coding can be useful for surveying the extent of species that are proving to be invasive, like this wisteria that's gone rogue around the Veblen House,

as well as for finding rarely occurring natives like this hazelnut, standing out from the surrounding honeysuckles.

Hazelnuts are real loners. There are three scattered specimens at Mountain Lakes, and only two found thus far in Herrontown Woods and vicinity.

Sourwood and Other Trees of Christ Congregation

Each year about this time, I make the pilgrimage to the Christ Congregation church to see their two beautiful sourwoods--a native tree I first encountered in the understory of North Carolina's piedmont woodlands. It's rarely planted in Princeton, and for some reason the USDA site shows it as indigenous to most eastern states but not NJ.

On Walnut Street, across from Princeton High School, the church has an interesting history with trees--a controversial one that came down some years back (see below), a new one coming up, and some nice mature specimens.

My visit happened to coincide with some bulb planting by Dwight Wilkinson, who declared he was a proud member of the PHS class of '62. The bulbs went in around a magnolia tree planted in memory of the church's five founders, one of whom was Dwight's father.

The magnolia turns out, like the sourwood, to be a species more typical further south--a southern magnolia (M. grandiflora). This particular cultivar, according to Dwight, is more cold-tolerant, with bright coppery undersides to the leaves.

The sourwood's distinctive golden seeds--its genus name Oxydendron refers to the finger-like rows of seeds--contrast with the brilliant red foliage. Dwight was glad to finally learn the tree's identity.

The two sourwoods are on the left, with an impressive specimen of American holly on the right.

The other side of the church is a good place to compare the mottled bark of the Korean dogwood (Cornus kousa)

with the cobblestone-patterned bark of the native dogwood (Cornus florida).

The controversial tree that came down years back was a big beautiful pin oak that was sacrificed so that the church could install solar panels in back, on the flat part of the roof. The relevant shade tree commission (borough?) defended the tree, but the church group brought data to the Princeton Environmental Commission, which I was on at the time, showing that the solar panels would reduce CO2 emissions by many times more than what the tree could absorb over its lifetime. Plus, the panels shade the roof from the sun much like a tree, and may provide some insulation in the winter. Only after considerable persistence did the church finally get permission to take the tree down. Even though the tree had looked to be in excellent condition, the town arborist later told us the cut portions showed signs of bacterial leaf scorch.

Monarchs Arriving in the Mountains of Central Mexico

I'd like to think that this monarch, which visited our backyard garden in Princeton, NJ on September 20 to feed on some ironweed nectar, is arriving today at its overwintering site in the mountains of Michoacan, north and east of Mexico City. The red triangle at the bottom of this map shows their destination. It's quite a feat for them to zero in on the tiny spot on the earth whose microclimate cradles them through another winter. The last leg of their journey, buoyed by favorable winds and guided by the mountains, is described here.

Another site offers insights into their arrival's cultural significance:

"Every year, the first monarchs traditionally arrive at their winter home in Mexico by the first of November. People connect the arrival of the monarchs with two events that take place in Mexico at the time, the corn harvest and Dia de los Muertos."

Be well, monarch. May your children's children visit us next year.

When Races Come to Greenway Meadows

What does a botanist do while waiting for the cross-country racers to come? Admire the seeds of common milkweed poised to take flight,

and the coppery tones of broomsedge (a native prairie grass).

It never occurred to me to run any distance anywhere, but what a great way to get kids out in nature, crossing countryside, taming a trail through a wild landscape, testing inner nature in a natural setting. Greenway Meadows: where the bright colors of running shoes meet earthtones, and toned muscles take to the hills.

Trouble For Princeton's Trees

To inoculate you for the news carried in this post, I'd like to point out that wishful thinking is not the same as hope. In fact, to the extent that it postpones action, wishful thinking can be thought of as the enemy of hope. Bad news is much more easily accepted if we feel confident in our capacity to work together as a community to respond.

Princeton has a real challenge ahead if it is to keep its protective canopy of trees in coming decades. There are the losses in recent years due to storms like Hurricane Sandy, the ongoing attrition as some pin oaks and red oaks succumb to Bacterial Leaf Scorch, and then there is the gathering storm just to our west of the emerald ash borer. Through a recently completed tree inventory, Princeton can now look at the numbers, and they don't add up--the number of trees likely to be lost dwarfs the number of trees being planted.

Doing the Math

Here are the numbers, rounded off for easier math, as presented by Bob Wells of Morris Arboretum, who directed the inventory and integrated it with an earlier survey of borough trees done by Jim Consolloy. These are only the trees growing in the street right of ways. Trees in parks, preserves, and on private property are not included. Of Princeton's 19,000 street trees, 3000 are in poor condition--unlikely to live beyond the next five years. Another 6000 are in fair condition, with an estimated life expectancy of 5-15 years. Even those trees in good condition are threatened by a growing collection of invading insects and diseases, along with the increasing weather extremes associated with climate change. For instance, some of Princeton's 1400 pin oaks and red oaks will continue to be lost to Bacterial Leaf Scorch.

Compare those numbers with the current replacement rate. Princeton purchases and plants about 60 trees each year along the streets. Its tree crew takes down about 250 trees each year in parks and along streets. The numbers offered up by the tree inventory estimates the annual loss of street trees to be a minimum of 600. By this math, we will be losing ten trees for every one being planted. And this doesn't even take into account the imminent arrival of the Emerald Ash Borer.

http://www.tinleypark.org/index.aspx?nid=648

Emerald = Less Green

Perhaps most worrisome is the looming threat to Princeton's most common tree, the ash. We can expect to lose most of our 2200 white and green ash trees along the streets in coming years, plus the tens of thousands in our woodlands. The culprit is the emerald ash borer (EAB), an insect that hitch-hiked to southeastern Michigan in wooden packing crates from China, then proliferated to kill 50,000 trees before anyone knew what it was. Since its identification in 2002, EAB has been radiating out across the midwest, killing tens of millions of trees, including a relentless spread eastward through Ohio and Pennsylvania to the border with New Jersey. A map at this link shows New Jersey essentially surrounded by infestations in bordering states.

As chance would have it, the original EAB infestation occurred just north of Ann Arbor, MI, where I used to live. The city of 100,000 had to spend $5.8 million removing 10,000 trees. Interestingly, ash continue to sprout in the woodlands there, and can grow to 6 inch diameter, but the chances of their growing to maturity are slim.

Princeton has dealt with threats to trees in the past. A bacterium called Bacillus thuringiensis (BT) has been used to reduce the impact of gypsy moths. According to Greg O'Neil, Princeton's arborist, the wooly adelgid's attack on our eastern hemlocks was slowed down by pesticide, after which the pest appears to have "cycled through", allowing many hemlocks to survive.

There is, however, no known control for emerald ash borer other than individually treating each tree, and even then the results are mixed. As an added complication, Imidacloprid, the most frequently mentioned systemic insecticide for protecting ash trees, may be contributing to the decline of honey bees.

What To Do

The sooner we acknowledge the depths of the challenge we face, the more proactive we can be, and the better the prognosis for Princeton's tree canopy. There are a number of actions that can be taken. Treatment for ash trees that are particularly cherished is best undertaken before the emerald ash borer arrives. To better spread the work of removal over a number of years, some of the younger or less healthy ash trees can be taken down and replaced with another species before the invasion hits. The municipality should at least be planning for the extra staff needs and the seven figure expense coming down the pike.

The big question is how to replace so many trees with a limited budget. The more gaps in the street canopy, the more pavement is exposed to the sun, which through the "heat island effect" causes the town to be hotter than it need be in the summer. At $200 a piece, new trees aren't cheap, and then there's the planting and followup care to insure they survive.

One approach I'm exploring, as a member of the Princeton Shade Tree Commission, is transplanting "volunteer" trees that sprout in people's yards. Some species are more appropriate than others, and determining where to plant them along the street requires some guidance. Perhaps we can come up with a guide, and motivated neighbors could take initiative in their neighborhood to identify gaps and work with willing homeowners to get trees planted in an optimal place and manner along the street. Given the infinite reasons that can be summoned for inaction, such an approach will only work if people see how their own needs can be met by participating in the collective endeavor of shading our streets.

For me, the hope lies in the growth force and the natural affinity people have for trees. It's remarkable how quickly the red oak in this photo, which sprouted on its own in my next door neighbor's yard not that many years ago, has grown large enough to cast much-needed shade on our driveway.

Neighbors a couple doors down have transplanted volunteer trees to key spots in their yard--to shade the house, provide habitat for birds, and provide buffer from the street. After just a few years, they are robust young trees--a white oak, pin oak, American elm and tulip poplar. Another friend is growing a pawpaw and a fig in a sunny spot in their backyard--going for food rather than shade.

Each kind of tree has its strengths and potential drawbacks and vulnerabilities, but after years in which Princeton's landscape was dominated by mature trees, it's refreshing to see young ones coming on the scene, filling the voids, reaching for the sun.

Related to this, the opening reception for an art exhibit entitled "The Fallen and Unfallen: Trees in Peril" is Nov. 1 at the DR Greenway, 5:30 to 7:30. More info here. With paintings and photographs, it celebrates trees while also identifying some of the threats they face, in little snippets of info like this one.

Rogers Refuge--The Care and Feeding of a Nature Preserve

Where in Princeton can you look out upon a marsh, and see or hear hundreds of species of birds along the nearby trails over the course of a year? Rogers Refuge is a star among Princeton's nature preserves, but it keeps a low profile in the lowlands just down from Institute Woods and just up from the Stony Brook.

A nondescript sign on Alexander Street, just before the canal bridge, directs you on to a nondescript road called West Drive.

Take West Drive to a fork in the road, where another sign, a little more emphatic, points you down the left fork, a narrow gravel road that winds through Stony Brook's broad floodplain. Watch out for potholes and cars or trucks coming the other way--a small water plant is located back there. There's a small parking lot on the right, with a path leading to an observation tower.

The Friends of Rogers Refuge help manage the property. Members Lee and Melinda Varian hauled the stone to improve this trail, a bit farther down the road from the parking lot.

The short trail leads to a birdblind.

Friends of Rogers Refuge (FORR) is associated now with Friends of Princeton Open Space, which is a certified nonprofit and can accept donations in FORR's name. Though the refuge adjoins the Institute Woods, the land is actually owned by the American Water Company, which teams with the town of Princeton to maintain a pump that keeps the marsh marshy during droughts. Both the Washington Crossing Audubon and American Water have provided some funding at various times to help with FORR's management of the refuge.

It's a great example of how preserves often need human intervention to sustain the quality of the habitat. Partners for Fish and Wildlife, part of the federal government, came in years back to knock out the highly invasive exotic Phragmitis reed that was taking over the marshy area. That is an ongoing battle, as will be the more recently arrived porcelainberry, seen here climbing up a tree, which has proven its kudzu-like invasiveness not far away at Princeton Battlefield. It's very difficult, as distracted humans, to nip these invasions in the bud, while the undistracted plants are quietly growing and expanding 24/7.

It is the friends group of volunteers that plays such a critical role in identifying problems, then harnessing and coordinating the resources of these private and governmental entities to protect this special habitat down along the Stony Brook. That, along with the labor of love that goes into maintaining the trails, replacing handrails on the observation tower that were hollowed out by carpenter bees, and all the other acts large and small, are gifts back to a nature that feeds us with its beauty and diversity.

Though the periodic meetings of FORR must deal with problems like invasive species and concerns about the downward trend in migratory bird numbers, much of the discussion is a sharing of joy at what birds were recently seen, which species are becoming more numerous as the habitat improves, and which guests the birdhouses have been hosting.

(The house in the photo looks great, but the less ornamental bluebird houses scattered through the preserve have been getting more tenants.)

Lots of other posts about the refuge can be found by typing the word "rogers" (no quotes) into the search box at the top of this website.

Roses and Sidewalks

Not that I want to stick my nose into another's affairs, but when another sticks its rose into a public thoroughfare, someone's bound to get a thorning without a warning. If the scent's not bred out of it, though, I might be predisposed to spare the air the thorn of my discontent, and stick my nose in the rose instead.

A Tree's Long (fantasy) Life in Death

What kid will be brave enough to knock on this door come Halloween? Actually, it looks pretty friendly, though the treats may prove too small to satisfy.

You can be forgiven if you don't recognize this intimate home in Princeton right off the bat.

Here's a hint: a stump along Hamilton Ave. bedecked with autumn clematis.

Here's another hint, across the sidewalk from the stump--the elegantly set table with an eternal bottle of wine ready for the guests who never seem to arrive.

If a tree must die, there is comfort in knowing it will live a long and productive life after death, feeding the micromultitudes and the imaginations of passersby, yielding ever so slowly its grip on the ground.

Poison Ivy for the Birds

Here are the lateral branches of a poison ivy vine that has climbed a tree. "Leaves of three, let it be" is a fairly reliable rule, though there are some other plants that have leaves of three, such as box elder.

On the lateral branches you'll find white berries this time of year. "Berries of white, run in fright" is the rhyme offered by the Washington Post's illustrated guide to "Poison ivy's toxic mnemonics". Lest we vilify too much, a friend at the NC Botanical Garden writes that "poison ivy fruits are reported to be eaten by more birds than any other fruit – so it’s an important food in the general avian world."

Of the hairy main stem of the climbing poison ivy vine, the Post article says "Hairy rope, don't be a dope", but the one I've heard is "If it's hairy, it's scary."

One scary result of research referenced in the Post article is that poison ivy grew twice as fast when exposed to 2007's atmospheric carbon dioxide levels, compared to 1950's concentrations. This begs the question of how other plant species are responding to our 40% increase in carbon dioxide levels in the atmosphere.

The lateral branches of poison ivy can be mistaken for the tree that the vine is using for support. Along the towpath, this gradient of autumn color from top to bottom suggest that the upper leaves get more sunlight, and so have a richer fall color. Some poison ivy leaves turn a brilliant orange in the fall.

Wooly Bears and Giant Leopard Moths

Bear with me, for though this wooly caterpillar bears some resemblance to a wooly bear, it is not. One of the Rotary Club volunteers helping out at Herrontown Woods this past Saturday (thanks Rotary Club!) had found a wooly bear earlier, but this one was bigger, and all black, without the wooly bear's middle patch of brown. Those are red stripes inbetween rings of fuzz.

It was quietly pillaging leaf matter from the slim pillar of a young black locust tree next to the trail that passes by the Veblen cottage. Some research yielded a name: Giant Leopard Moth, and if you look at the photos of the adult moth, you'll find the name's likely source is a snow leopard--white with a beautiful pattern of black dots. "Giant" in this instance refers to its 3 inch wing span.

Both the wooly bear, alias Isabella Tiger Moth (Pyrrharctia isabella), and the Giant Leopard Moth (Hypercompe scribonia) are in the family Arctidae, which like the Arctic is rooted in the Greek word for bear, Arktos. The Great Bear and Little Bear constellations, being built on the Big and Little Dippers, are on either side of the North Star. The wooly bear's range actually extends up to the arctic. Both species will overwinter in their wooly state, then form a cocoon in the spring. The wooly bear in particular is seen this time of year crawling around looking for a good crevice to spend the winter in. (Posts about overwintering wooly bears here and here.)

This is all one leaf on the black locust (Robinia pseudoacacia). Unlike many caterpillars that are very picky about their host plants, the Giant Leopard Moth caterpillar feeds on many species, including dandelions.

Lions, leopards and bears, oh my. 

Life and Death Among the Flowers

A well-coiffed frontyard garden on a quiet street. I was standing there talking to a friend, watching the bumblebees peacefully feeding on nectar, when I saw something else move in the mass of blue flowers.

That something else was watching the bumblebees far more intently than I. As a bumblebee alighted on a nearby flower, the praying mantis would tilt its head to get a closer look, shift its claw-like front legs, patiently waiting.

I continued to talk with my friend, while wondering if a bumblebee would land close enough for the praying mantis to strike.

The mantis must have known it was just a matter of time. Location, location.

Obviously, no ethical standards have been developed in the mantis world about waiting for the prey to die before starting to munch.

Few of us will get to see lions stalking wildebeest in the Serengeti, but every now and then, a similar drama can be caught by an itinerant eye, no farther away than a neighbor's garden.

Black Walnut Harvest

A friend is very excited about harvesting black walnuts this year, having heard great things about their health benefits. There's the small matter of reaching the meat, however, well guarded by the green hull and the extremely hard shell.

One technique for removing the hulls is to drive over them with a car. Traffic along Harrison Street was being very cooperative in this regard, but I was a little leery of collecting nuts so close to a busy road.

If you're moved to give black walnut harvesting a try, here's one of many links with instructions.

Most walnuts go begging, like these on the lawn at Brearley House. That leaves an abundance for those willing to give harvesting a try. Best to be armed with a good nutcracker. Below are the results of my research.

Smaller nutcrackers like the Reed get high marks for everything but black walnuts, so you'll need something larger and stronger.

Here's a recommendation from a friend: "I have a Gardner nut cracker which I am very happy with… I think the cost is around $80 and it works very well with thick-shelled nuts like black walnut, butternut, and hickories and hicans. (I am also told there is a Chinese knockoff to be avoided.)" He also mentioned a Kenkel model.

There's also a Hunt nutcracker that came up in an internet search.

Some Kingston Greenways Events

Some good stuff happening just down the road:

Annual Meeting, Kingston Historical Society , Wednesday October 9, at 7:30 pm at the Kingston Fire House on Heathcote Road, Kingston. After a very brief business meeting, William Flemer, IV will give an illustrated talk about the Princeton Nurseries

Fall Foliage Walk, Kingston Greenways Association , Sunday October 20th, 2pm at the Mapleton Preserve/ D&R Canal State Park Headquarters, 145 Mapleton Road, Kingston, New Jersey, Rick Henkel will give guided walk through The Mapleton Preserve and other parts of the former Princeton Nurseries Kingston Site

Check the links for more info and background.