Saturday, November 26, 2016

Norway Maples, and Seeing the Future

One purpose of this blog is to help people to look at nature now and see where it's headed. Every gardener imagines the harvest while planting the seeds. In science, one extrapolates from past and current trends to predict the future. With practice, one can look at a woodland and see not only the present but past and future as well. As a land manager, one envisions two futures--one without intervention, one with. Because we've altered local habitats so much--through altered hydrology, past farming, introduced species, banishment of important forces like fire and predators like mountain lions and wolves--intervention can help restore functionality that no longer happens naturally.

Autumn is the easiest time to divine a woods' future, because each species shows its colors, making trends easy to spot. For instance, learn the Norway maple's brand of yellow this time of year, and you'll start seeing them all over town. Unpalatable to deer, they rise unnoticed until they become full-sized trees, mostly along backyard fencelines.

That's what's happening on a larger scale in the hidden valley between the Princeton University chemistry building and Washington Road. That mix of yellow and lingering green indicates that the Norway Maples are taking over the top of the valley,

and extending downstream. This is the perfect time of year to see the extensive invasion by this nonnative tree. Why have I on multiple occasions urged the university grounds staff to cut or girdle these trees, despite their attractive yellow in autumn?

The problem is an ecological one. This forest, one of Princeton's oldest, is steadily shifting from native trees that feed local wildlife to nonnative vegetation that does not. As the shade-tolerant Norway Maples push up into the native canopy above, their competition for water and nutrients weakens the giant oaks and black gums, hastening their decline and increasing their susceptibility to wind storms. Young native trees--preferred by deer and less shade tolerant--can't compete with the Norway Maples, which grow quickly, green up sooner in spring and drop their leaves later in the fall. This photo shows a 1-2 centuries old oak with a sea of Norway maples rising underneath.

Fortunately, most Princeton woodlands have not been invaded by Norway maple, though it would be worth it for land managers to take a walk through the woods to see if they are starting to get established elsewhere in Princeton's open space.

Except in that Washington Rd. gorge woods, they have proven invasive only in people's yards, showing highly localized invasiveness much like Japanese maples and Rose of Sharon. This photo, taken along North Harrison Street, shows the classic problem with ignoring the silent ascent of Norway maples, in this case under a powerline. Chances are they grew unnoticed by the homeowner, and now will require repeated pruning to keep them from threatening the wires.

At least the half of the tree closer to the street shades the pavement in the summer,

but another annoying aspect of the species--their dense shade and aggressive roots that leave little sun or water for the lawn--has made it impossible to grow grass on the steep slope.

Like climate change and the nonpoint pollution of our waterways, the Norway maple silently transforms the world, undermining food chains and biodiversity, while our attention is elsewhere.

Friday, November 25, 2016

Nature/Geology Walk at Herrontown Woods: This Sunday, 1pm

This Sunday, we'll gather at Herrontown Woods to 1) be out in the woods on a brisk day and 2) learn something about the magnetite that's in some of the boulders and streams there. All are welcome.

A few years ago, one of our Friends of Herrontown Woods board members, geologist Jon Johnson, discovered that some of the boulders in Herrontown Woods are magnetic. He tested pebbles in the streambed and tracked the magnetism upstream to its source in the boulders of the ridge. It's a non-extractive and, of course, non-remunerative version of prospecting for gold. There's a previous post on the subject at this link.

We'll also aim to pass by the area where large boulders were quarried at some point in Princeton's history, leaving big holes in the ground where a boulder had been.

Meet this Sunday, Nov. 27, at 1pm at the Herrontown Woods parking lot, off Snowden Lane. Maps can be found at html.

Thursday, November 24, 2016

How to Thank a Leaf

On this day of gratitude, I would like to thank leaves of all kinds for all they do, for all the CO2 they eat, and all the treats they make possible, with their patient translation of sun into sugar. As if that weren't enough, they close the summer's show by becoming candy for the eye, then fly and fall in a dance with gravity, to blanket and feed the earth upon which all depends, though we pretend otherwise. How do I thank them all, where they lay in humble anonymity, while we brag and boast and think ourselves the center of the world? And how do I thank the windblown leaves that raced along with my bicycle a week or two ago? The wind at our backs, they cheered me down the sidewalk like a tickertape parade, as if all the world were going my way.

Monday, November 14, 2016

Trees By the Light of the Supermoon

By the time we saw the supermoon last night, it had risen well beyond the horizon. My older daughter wasn't impressed. "I've seen it bigger," she texted. Au contraire, mon fille. The last time the moon was this big was before our time, in 1948.

Don't ask me why the moon would want to venture closer to the earth, and thus look bigger, given all that's going on here. I'd recommend that all heavenly bodies keep their distance, lest we decide to export our brand of planetary stewardship.

The moon made a fine backdrop for scrutinizing the twigs and acorns of a pin oak,

and the leaves of a red oak in the front yard.

That's Quercus rubra to botany types, with hints of Batman.

The neighbor's spruce tree got in the act.

This shot managed to capture some of the texture of the moon's surface along with a few scraggly pin oak leaves.

Given a preoccupation with earthbound interests, this is one of the few times I've pointed my camera skyward, in contrast to my father, who as an astronomer spent much of his time photographing the universe, and then developing the images in a darkroom in the basement of Yerkes Observatory. The school librarian back then made this lamp, with images captured by the observatory's famous 40" refracting telescope.

The moon will be pretty super tonight, too, if the clouds hold off.

Thursday, November 10, 2016

Nature Walk at Herrontown Woods: the Color-Coded Forest, Sunday, Nov. 13, 1pm

Trees and shrubs are still showing their true colors up along the Princeton ridge this week, making it possible to tell at a glance what species surround us. We'll decode the forest, see what we can see, and find some solace in the woods. All welcome.

Meet this Sunday, Nov. 13, at 1pm at the Herrontown Woods parking lot, off Snowden Lane. Maps can be found at html.

This photo of hazelnut is from a 2013 post on the color-coded forest at this link.

Hidden Nature and Drama at Quarry Park

It doesn't look like much of a nature trail, this paved walkway that makes a broad circle around the perimeter of Quarry Park.

But what's this? On one recent visit, it was clear some youthful imaginations had turned this peaceful park into something far more dramatic. There was evidence of defenses assembled against attack, Swiss Family Robinson-style. A wall of sticks had been constructed across the trail, to slow any invaders, and caches of ammunition the size of small cannonballs stashed here and there. It took me back to my own childhood landscape, stashing horse chestnuts in strategic spots for later use. I don't remember any actual attacks, but the preparations were serious business.

A stump and a clearing near Spruce Circle are the legacy of another bit of drama, when powerful winds swept through a few years ago, knocking down a grove of trees.

One of the resprouts, a black locust, bears thorns that may once have provided vital defense, but now seem, like the kids' defenses, to be aimed at imaginary foes.
Head down the path at the lower end of the park, and the plain lawn yields to some diversity. Here's a smooth sumac,

and a white pine dropping its older needles.

It's been a good year for white snakeroot, whose scientific name was recently changed from Eupatorium rugosum to Ageratina altissima, apparently to vex botanists who commit scientific names to memory. The plant is common in part because it is toxic, discouraging the deer.

Japanese knotweed can form dense, exclusionary masses along the banks of the StonyBrook elsewhere in Princeton, but on this upland soil in the shade it seems benign,

with attractive seed structures.

Sure enough, growing in the midst of a default thicket of honeysuckle shrubs at the bottom of the park, one osage orange tree, bearing not oranges but these curious green balls, which may once have been dispersed by megafauna, but now clearly get around thanks to kids. The tree has a rich history, with remarkably dense and rot-resistant wood used for bows and fenceposts.

Sunday, November 06, 2016

What a Little Dew Can Do

Here's a bit of serendipity. Shadows play upon the grounds of Princeton Battlefield, charmed with dew on a Saturday morning.

Ever the resident tourist, a shadow selfie with Mercer Oak II. Had no luck getting the shadow to smile.

Sorry, but you can't look at any screen--TV or computer--without at least one obligatory car commercial popping up. The sound track runs something like, "If George Washington were alive today, ...", though he might eschew fossil fuel altogether and stick with a horse. Those founding fathers thought about long term consequence. What ever happened to that kind of thinking?

The original motivation for stopping during a drive by of the Battlefield was documentation, not aesthetics: to photograph the invasive porcelainberry overgrowing flowering dogwoods planted as part of the nation's bicentennial celebrations in 1976.

One of my recurrent cause celebres is to save the Dogwood Garden Club's dogwood legacy from the aggressive vine growth. From the green/yellow of the porcelainberry vines crawling over the red leaves of the dogwoods, you can see who won this year's skirmish. The Dogwood Garden Club doesn't know who I am, and for all I know they've forgotten that they ever planted these trees along the field's edge in the first place.

There was also an obligatory photo of the great disappearing bamboo patch. Two years ago, this was a thick clone of bamboo growing out over the path down to the Quaker Meeting House, but a series of well-timed cuttings with magic loppers over the past couple years have sapped vigor from the bamboo's giant root system. The decisive strategic intervention came this past June, when Kip Cherry and I cut down the regrowth from a cutting in the spring. It was some inconvenient toil, but deprived of any payback from that big investment in regrowth--two years in a row--the bamboo has nearly given up. A visit next spring should be light work, followed by a refreshing beverage on the Clark House porch.

Dew was also working some magic on the vista on Quaker Road near the towpath. Scattered pin oaks in a field of goldenrods.

Thanks goes to my daughter Anna for getting me out that way early on a Saturday, to drop her off for a busride to Philadelphia to do some canvassing. Otherwise, that encounter with morning dew would have never happened. Finally, a reason to be thankful for this election season.

Tuesday, November 01, 2016

An Unexpected Halloween Visitor

When my daughters came in the house yesterday evening to report that a raccoon had scared them en route to closing up the chicken coop, it didn't even occur to me that it happened to be Halloween night.

True, there had been a curious masked visitor in the backyard earlier in the day, someone wearing a wig and his favorite CD. That two minute selfie session with a cellphone had been the full extent of our observance of Halloween, other than the white plastic pumpkin decorating the "Wishing the Earth Well" leaf corral out front next to the sidewalk. Our street is not popular with trick or treaters to begin with, and we did nothing to lure them.

The lack of lights and decoration did not deter the night's one trick or treater from showing up, however, not at the front door but behind the house. Though raccoons are considered ubiquitous urban denizens, we had not seen one in the neighborhood since 2004, when a confused specimen passed through our backyard, looking lost.

My daughter's sighting didn't come as a complete surprise, though.

First, it explained what, or who, had been bending the wire fencing of one of my backyard leaf corrals, in a recurrent and unsuccessful attempt to get at its inner core of kitchen scraps. The rotting lettuce and old dogfood, out of reach behind hardware cloth, was the treat, and it was surprising the raccoon hadn't figure out a trick to get at it.

Second, there was the question of whether the raccoon's interest went beyond kitchen scraps to include our four chickens, two of which had taken to roosting in nearby evergreens and bushes rather than taking shelter in the coop. The assumption is that, come winter, if winter comes, the chickens would drop their summer dalliance with self-sufficiency and take refuge in the coop at night.

The girls gave me the flashlight, to lead the daring expedition back to where the raccoon had been spotted.

"Do you think it has rabies?", one of my daughters asked from behind me, not understanding why I wasn't more fearful. When I see a raccoon, I'm cautious of course, but inside, my heart begins to melt. My thoughts return to when they would visit my childhood home, surrounded by woods at the end of a road on the outskirts of a small Wisconsin town. They had been getting into our garbage cans, and all attempts to keep them out had failed.

One day, in broad daylight, a raccoon showed up in our side yard, sad looking, weak, clearly a reject from raccoon society. We named it Rangy, for its bedraggled appearance, took pity on it and gave it some food.

It may have been about this time that my father realized that, if we put our food scraps in a pan next to the woods, the raccoons would leave our garbage cans alone. This proved to be the beginning of a wonderful friendship. As the raccoons began to visit the pan, we decided to install a light to illuminate the edge of the woods, the better to see them. Soon we were tossing them peanuts in the shell from an open window. Closer they came, caution slowly yielding on both sides, until we reached the point where we could step out onto the back patio, hold a peanut out, and they would approach. They'd stand up gracefully and reach for it with those wonderful, delicate paws, take the peanut gently and scoot a short distance away to feast upon it. More and more came. The grownups would bring their young the next year. One night we counted 16. Rangy the Reject had spawned a coming together of human and raccoon society.

This was the era of books like Rascal, and Raccoons are the Smartest People. We knew what rabies was, had seen it occasionally in the odd behavior of an animal--like the groundhog that confronted me on a town street while biking home from school--and we respected the wildness of raccoons too much to consider having one as a pet. But that didn't deter us from appreciating all that is wonderful about them. One evening, we opened the kitchen door to see four raccoon cubs climbing on the screen door, their mother on the porch behind them. The mother was Whitey, the tamest and most gentle of them all, named for the beautiful white fur on her underside. She had brought her new family to meet us. By then, we were actually letting her come in the kitchen door a few feet to get peanuts. Somewhere, there's a photo of her reaching up to touch the knob on our little black and white TV. Of course, we always made sure she had an escape route, so as not to feel trapped. No one ever dared get between her and the open door.

The raccoon that visited us last night, like Rangy long ago, also seemed like a reject. It didn't run away at our approach, but instead remained perched on the fence, looking at us. Though large, it seemed weak and slow. Finally, it climbed awkwardly down the fence and disappeared into the dark.

To be on the safe side, we decided to pluck Buffy, the last of our first batch of chickens from five years ago, from her perch in a nearby lilac bush, and put her in the coop with two others. We closed the coop and headed back in.

To some extent, our free range chickens offer a similar experience to what I had as a child. We feed them, but mostly they forage for themselves, tame and yet living their own lives. Where once I delighted as the wild became more tame, with the chickens we watch as the tame explore aspects of the wild. Last night, those two worlds intersected next to the chicken coop. I thought of leaving some food out for the raccoon in nights to come, but then thought again. How to handle this convergence, for the good of all involved, is not at all clear. I don't expect any reprise of a childhood in small town Wisconsin. Whether the answer is trick or treat, our backyard Halloween is just beginning.