Monday, October 31, 2016

Wawa Grows a Prairie

Wawhat's the Wawa growing? A bit shaggy for a butch cut. The proof is in the roof. Clearly, the Wawa at the Dinky station has gone green, or tawny, depending on the season. Take the building out of the picture, and you have a prairie out in big sky country. For a botanist, the question is not how all those prairie grasses got there--Princeton University has been designing green roofs into, or onto, a number of buildings in recent years--but whether the grass is little bluestem or broomsedge. Time to pull out the ladder for closer inspection. A vegetated roof reduces stormwater runoff from the building, and also provides insulation.

Another aspect of the Dinky Station's landscaping: Most of the trees are Kentucky coffee trees and a thornless version of honey locust. Both of these species tend to leaf out late in spring and drop their leaves early in the fall. Both are relatively rare in local woodlands, in part because their seedpods were in the deep past eaten and spread mostly by America's now-extinct megafauna. They make great landscape trees, though, because they leaf out late in spring and drop their leaves early in the fall. That means they shade the pavement and buildings only during the warmest months, then generously allow the sunlight's warmth to reach the ground during fall, winter and spring. Some research might show that the trees' internal clocks and large seedpods evolved in an ice-age world of short summers and big animals with fur the length of the Wawa's roof.

The bark of the Kentucky coffee tree has a characteristic chipped appearance,

in contrast to the smooth bark of the honey locusts.

Here's a grove of honey locusts letting October sunlight reach the south-facing windows of the Dinky Station.

Found a past post about Dinky wildlife, and a post in which the vibrations of the Dinky's approach makes the trees dream of megafauna past.

Thursday, October 27, 2016

Gratifying Restoration Work Near Herrontown Woods

Just down the hill from Princeton Community Village, not far from Bunn Drive, there's a clearing in the forest. The gap in the canopy has allowed sunlight to reach the ground, and the non-woody plant community has responded with billions of white flowers generated by a sprawling wildflower with a sprawling name, late-flowering thoroughwort. Built into the slope you can see what looks like a little dwelling. In fact, the structure and the giant berm its built into were constructed to help protect downstream land and houses from the rainwater that rushes off of Princeton Community Village's streets and roofs during storms. The field of pollinator-friendly wildflowers is some serendipity that our Friends of Herrontown Woods group has informally adopted. We were here to do some weeding, to proactively ward off a takeover by invasive nonnative species.

Mixed with the weeding was some appreciation of the engineering that makes this detention basin serve an ecological and flood-control function. As water enters the basin from Community Village and Copperwood, the aim is for it to seep into the ground, to serve as an underground reservoir to sustain Harry's Brook. But if water remains in the basin for a long time, it will drown the vegetation, so there needs to be a way for excess water to be slowly drained from the basin.

At the bottom of the tower is a small opening for slow release, protected from blockage by the bars.

In a big inundation, a larger hole further up the tower allows faster release of excess water. And then if a megastorm fills the basin close to overflowing, water pours into the big opening at the top of the tower, to keep water from overtopping the berm. Whether much runoff actually reaches this basin from the nearby housing would require stopping by after a deluge.

Cattails and a pretty sedge called woolgrass (Scirpus cyperinus) thrive in the moist soil at the bottom of the basin, intersecting with the thoroughwort on the berm.

Here's a closeup of the woolgrass's ornamental seedhead.

It looks like a peaceful scene,

but along the pipeline right of way nearby, one can see the invasive power of two nonnative species on display. Mugwort, along with the newer arrival, Chinese bushclover, have claimed large sections of the pipeline land, and the same process is at work on the basin's berm. Why the Chinese bushclover is problematic ecologically is described at the bottom of another recent post.

Kurt Tazelaar joined me at the basin with an hour or two to spend and a clear mission: to dig up and remove all the Chinese bushclover we could find before its seeds matured. Our timing was pretty good. The seeds weren't loose, and we were catching the invasion early, when complete removal was still possible.

Here's the incredible root system of a Chinese bushclover--great for erosion control, but awful for biodiversity as the species spreads and outcompetes native species.

Though we achieved our goal, the elephant in the clearing was the mugwort, which is far more numerous and will require a far more ambitious intervention.

There was some good news to be seen with another invasive species at the basin--purple loosestrife. It showed clear signs of deer browse, which means the deer in this case may be helping limit its capacity to dominate the wet areas.

Two hours spent with shovel and clippers, two bags filled, we decided to declare victory and head home.

Wednesday, October 26, 2016

Some Autumn Splendor

Time to paint the town red

(with black gum leaves). Probably a sugar maple in orange on the right.

A thornless variety of honey locust keeps yellow in the game.

This brilliant red winged euonymus (burning bush), is the same species that has spread into Princeton's woodlands, where the shade diminishes its color to pink, or even ghostly white, in the fall.

A picturesque patch of poison ivy growing safely away from foot traffic, beneath evergreens where the Westminster Choir College grounds extend down to Hamilton Ave.

Winged euonymus can turn a rich orange or burgundy.

Enjoy the ashes while they're still around. The mix of purple and yellow hues on a whole tree can seem almost to pulsate.

Lots of variety in ash leaf color.

Hard to know why the top half of this maple on Aiken Ave. would turn long before the bottom. A tree across the street may have been shading the lower half, delaying its shift to fall color.

Each leaf on a redbud or spicebush can have its own schedule.

The big bluestem grasses planted at our new native meadow at Smoyer Park look to be a midwestern variety. In the midwest, the prairie grasses can turn such brilliant colors that they appear to be on fire, mimicking the prairie fires that help them to prosper. Local members of the same species are much more muted, for some reason.

Woodgrass, actually a sedge, ornaments a constructed wetland.

Saturday, October 22, 2016

Feeding Raingardens: When Disconnection is a Good Thing

This post is about two different kinds of disconnection, one good, the other not so good. Now, every time I start saying what something is "about", I am stopped in my tracks by the memory of an english professor, Russell Fraser, who would say emphatically that a poem is not "about" any one thing, in that a good poem comes from a place so deep and works at so many levels that it's naive for the conscious mind to declare what the poem is actually about.

Take as a for instance this newly constructed raingarden behind the PNC's new bank at Princeton Shopping Center. Not exactly a poem, but what is it about? For the designer, who may not have even visited the site, it was about satisfying regulations, at least on paper--regulations that require that newly paved areas not add runoff to local streams. For the contractor, it was a matter of nominally following the design, installing the called for curbcuts and greenery, and being done with it.

At a deeper level, this raingarden demonstrates what happens when people are disconnected from the underlying meaning of their work. The whole idea here is to direct runoff into the raingarden, where the water can be filtered and seep into the ground, essentially "disconnecting" that portion of pavement from the matrix of stormsewer pipes that would otherwise send untreated runoff pouring directly into nearby Harry's Brook, adding to downstream flooding. Look closely, and you'll see how this good sort of disconnection was foiled by a lack of empathy for the basic processes of nature, one of which is that water flows downhill. The runoff can't reach the raingarden because the turf and stone around it are higher than the pavement.

At another level, then, this raingarden is about how a big investment in regulation, design and installation, well intended on its face, can come to nothing.

A bit shadowy here in the photo, but you can see the surprisingly small amount of pavement uphill of the raingarden. The plants really need what little runoff the pavement can provide.

This second curbcut is the most obviously dysfunctional one. A visit during a rain will show runoff simply flowing past it, as if the curb had no cut at all. I suppose as parents we sometimes expect of kids what their nature does not allow, and this curbcut is expecting water to flow uphill. Not likely. It comes down to empathy for the physical world--being able to imagine the flow of water, and the consequences of gravity.

Meanwhile, up Bunn Drive from the Shopping Center, in the parking lot for Stone Hill Church, the raingardens were designed with much more care. The mounds of green and gold are switchgrass--one of the native prairie grasses that works well as an ornamental.

The long raingarden is lower than the pavement, and the curbcuts actually let the water in.

This last photo, back at the Shopping Center, shows how the best way to disconnect can be simply not to connect in the first place. Where no curb was built, the grass meets the pavement directly and runoff can flow into the turf, then be absorbed into the ground. Where the curb ends, where the informality of curbless streets are allowed, better runoff management begins. A chance configuration, with pavement higher than the lawn next to it, is working better than the fancy design of curbcuts and raingarden just a hundred feet away. Here's to the serendipity that sometimes comes from "not doing", and here's to PNC being required to call the contractor back in to make their raingarden actually work.

Wednesday, October 19, 2016

This Fall, Corral Those Leaves

I'll never understand why the human race throws certain things away, be it leaves or a hospitable climate. The two seem far different, but it's all one needless and tragic purging, a throwing away of nature's gifts while curiously courting danger, present and future. Some of my most vivid and happy memories from childhood involve leaves. One year I took the white oak leaves in our yard and raked them into rows to make a house, then rode my tricycle through the various rooms. Some leaves we burned, perfuming the autumn air. We'd throw acorns into the embers and wait for them to pop. And there's the memory of the whole family raking leaves down the hill, a row of leaves, dancing before us in bright sunlight, growing in size, to make a big pile at the edge of the woods. With my friends, I'd run down the hill, launch myself into the pile, to be enveloped in its crisp embrace. My walk to school was essentially a nature walk, through woods, down a mix of narrow paved and unpaved roads. One maple tree had particularly bright leaves with orange, yellow and red, to pick up and take to art class.

Now I live in a larger small town, a Little Big Town (like the Dustin Hoffman movie Little Big Man), on a busy street, and though I cannot stem the odd and hazardous tradition of piling leaves in the way of cars, bicyclists and pedestrians, or the stampede of traffic spilling gases into the air, I can toss leaves into a leaf corral, in what seems to me a more sustaining and spiritual approach to the physical world. The leaf corrals are an experiment in no-work, no carbon footprint composting. This fall, the corrals' contents, decomposing passively all summer, were inspected to see the results. This particular corral--called a Wishing the Earth Well because it's a well that works in reverse, giving nutrients back to the earth--includes a central cylinder made of critter-proof hardware cloth, where food scraps can be thrown and allowed to decompose, surrounded and disguised by a donut-shaped column of leaves. Yield of this 3 foot diameter corral was one and a half big tubs of compost, and a retrieved teaspoon from the kitchen that somehow got mixed in with the food scraps. There was also an effort to grow potatoes and nasturiums, which showed some promise. A botanist, by the way, will watch a movie like Young Frankenstein and come away wondering what Gene Wilder meant when he said "Never be nasty to nasturiums." Was he speaking metaphorically, or was it just something that needed to be said?

A larger corral, six feet wide and called the OK Leaf Corral, yielded five big tubs of compost ready for incorporation into the garden beds.

Here's a closeup of the compost, soft and spongy, dark and rich. Ah, the rewards of all that non-labor and non-burning of fossil fuels.

A neighbor who tried this leaf corral approach said his leaves didn't decompose, which probably meant they were dry. I, too, noticed in midsummer some pockets of undecomposed leaves in the piles, and came up with a novel approach to improving decomposition without having to turn the pile. This root feeder, normally used for fertilizing trees, can inject water into the leaf pile while also making channels for rainwater to penetrate. A few minutes of poking around was all it took to get the interior of the pile moist, and enable the decomposition of the red oak leaves by end of summer. Moisture, along with all the decomposing fungi, bacteria and insects, also enter from the ground beneath the pile.

Here's the prettiest leaf corral, which you'll have to take my word for because it's completely disguised by a dogwood tree. In other words, leaf corrals can blend into the yard, disguised by foliage while they quietly work their decomposing magic. A nice surprise last fall and winter was how the leaves would quickly settle in the corrals, after just a few days, allowing more leaves to be added as the trees slowly let them go. A leaf corral performs, then, as a bottomless receptacle for leaves.

In its simplest form, a leaf corral is made of green wire fencing, 3-4 feet high, with a couple stakes to hold it in place. Some folks in town have asked me to make leaf corrals for them, which I'm happy to do at cost, along with a donation to our Friends of Herrontown Woods.

Friday, October 14, 2016

Monarch Meadow and Mating Mantises

Each fall, I help a Princeton homeowner weed her marvelous meadow. It's light work because in past years we nipped a couple invasions in the bud, pulling out small patches of mugwort and Chinese bushclover--species that have taken over long stretches of the gas line right of way nearby--and bagging up the seedheads to prevent spread. We found only a few individual plants this year. I recommended removing some Queen Anne's Lace as well, a lovely flower that, alas, I've seen take over fields in the midwest, where it's more established.

Interestingly, what's causing some imbalance in the meadow are some of the native goldenrods, whose advance across the whole field is cutting back on populations of other wildflowers. This is a common shift in meadows. Many native goldenrods spread via rhizomes--roots that spread laterally and sprout new plants, creating expanding clones. I sought advice on the internet for how to bring the goldenrod back into balance with all the other desired meadow species. Midseason prescribed burns? Spot spraying with herbicide? Pulling individual plants? The online search yielded no clear solutions.

We watched a monarch sampling the meadow's millions of flowers, and then my eye caught something else entirely, a pair of praying mantises preparing to mate.

The male, smaller, clung tightly to the female's back. Weeding gave way to nature study, mixed with voyeurism.

A wasp had been visiting a flower just above them. The next thing we knew, the female was clutching the wasp in her claws and chowing down as if the wasp were a shish kebob or an ear of corn. This casual and timely catch of dinner in the midst of procreation, as we learned later, was really good news for the male.

Nice of them to show us their business ends--male on the right. Had a hard time later on finding any nomenclature or function for the antenna-like structures at the posterior end of both male and female.

Several times, the male curved its abdomen over and under the wings of the female. This capacity to bend around may have something to do with the male's greater number of abdominal segments (8 vs. 6), which along with overall size is useful for distinguishing one from the other.

My friend said she'd read that the females have a habit of eating the males after mating. For some reason, I found this disturbing. Is evolution trending in this direction? All the more reason for the male mantis to think twice about breaking out a cigarette.

There are in fact, for your viewing pleasure, videos that capture this charming behavioral trait, and explain that the female is merely reaching for the nearest high-protein meal she can find, to nurture the next generation. And what sort of life does the male have to look forward to, with frost quick approaching?

One video shows that the female begins by eating the male's head, suggesting little respect for the male's intellect. The beheading can cause the male to mate all the more ardently, as if knowing this is its last chance. Plants can have a similar response to stress, bearing abundant seed when death seems imminent.

At some point, my friend's dog navigated its way past us, plowing its way through the dense wildflowers. It may have been at this juncture, with the female mantis distracted, that the male got going while the going was good. It flew a short distance away, looking a bit like a helicopter, its long body suspended below four wings catching the bright afternoon sunlight. Cockroaches, a close but less beloved relative of praying mantises, fly in the same manner.

The female, perhaps satiated by the little snack of wasp earlier on, didn't react. One bit of advice for any male praying mantises that might be reading: though praying could help, it's best to bring a little snack along for the misses. Small acts of kindness could take the female's mind off of biting your head off. Although, given your imminent demise as winter approaches, giving your body to feed the next generation could improve prospects for your progeny. Tough choice.

Though there are native praying mantises, we mostly encounter the two species introduced from China and Europe. I just hope they stick to wasps, and each other, and don't include monarchs in their diet. A quick googling brings up this post, which suggests that we may want to reassess our view of praying mantises as an unalloyed good.

(Track the Monarchs' progress towards Mexico at this link.)

Saturday, October 08, 2016

Event this Sunday: Milkweeds and Meadows

UPDATE: Rain continuing through to noon. The basins are busy doing their good work. Will reschedule.

Let's say the rain will have passed by tomorrow morning, in which case you are welcome, this Sunday, October 9 at 9am, to join us at the Smoyer Park wet meadow. The park's out Snowden Lane in Princeton, just before you reach Herrontown Rd. Drive down to the end of the park's parking lot, where we are converting a large detention basin into a native meadow. After describing the process of converting turf to meadow, we'll plant some milkweed contributed by Don Stryker, property manager at Princeton Friends School. Don has been restoring the woodlands behind the school, and would like to establish more populations of milkweed in town. He found out about our Friends of Herrontown Woods nonprofit during a walk through the preserve, which is just across Snowden Lane from Smoyer Park.

After planting the milkweed, for anyone interested, we'll head around to the other side of Herrontown Woods, park at Hilltop Park, and walk down to the massive detention basin that receives stormwater runoff from the roofs and streets of Community Village and Copperwood. I recently visited the basin with students from Princeton Learning Cooperative. Underneath the masses of late-flowering thoroughwort, which make for a striking effect along the giant berm,

we found small populations of mugwort

and a particularly worrisome invasive called Chinese bushclover. Mugwort forms monocultures along the nearby gas line right of way, and the Chinese bushclover has been showing up in a few places in Princeton, with the same potential to aggressively displace other species.

Recent rains and unripened seedheads make this a perfect time to pull out these two species while they are still few in number along the berm.

If you're at loose ends tomorrow morning and would like to help out, bring work gloves. A spading fork is also useful to lift the roots of the Chinese bushclover. With soft soil, the mugwort is small enough to pull by hand.

There's a sad story of how Chinese bushclover was planted widely by departments of transportation and gameland managers, touted as a wildlife food only to discover that its seeds were too small and tough to digest. Birds then spread it around without gaining any nutrition. Native bushclovers with digestible seeds were displaced, and wildlife ended up worse off. I once tried to manage a right of way in North Carolina for native bushclovers, but it's really tough to remove the nonnative species once it becomes established. Thus, the proactive weeding expedition tomorrow morning.

Some technical info here: A thorough compilation of information on Chinese bushclover (Lespedeza cuneata):
Surprisingly, the research that questions the habitat value of the species dates to the 1940s and 1960s, so the view that the seeds are too small and tough to digest appears to date back a long ways. This post includes a photo comparing seed size of native bushclovers and L. cuneata.

Wednesday, October 05, 2016

A Weeding in Time Saves Nine

My daughter and I planted one of the raised beds at Princeton High School with wildflowers. Part of the logic was that attracting pollinators to the area would be beneficial for the vegetables being grown in some of the other raised beds.

Not sure if there's actual data to that effect, but what was clear is how easy it is to make a wildflower in this framed context thrive. Easy does not equate with the "plant and run" approach, which typically involves planting a garden and then assuming nothing more is entailed than patting oneself on the back. Instead, easy means planting wildflowers where they are likely to thrive, and then making brief but strategic follow up visits to water during droughts or weed out any would-be competitors. This planting required two or three follow-ups of a half hour each, until the wildflowers were so well established that nothing else had a chance.

Care of the other beds varied from neat rows of vegetables to a rambunctious weedfest, like this one with pigweed (amaranth) and lambs quarters--the taste of at least the latter when young rivaling any of the greens intentionally being grown.

Horseweed and ragweed, both native, are also quick to populate bare ground.

Here's ragweed closer up, with a foxtail grass. All of this is on the backside of the high school, where plants don't have to conform to cultural norms of beauty.

If ever the school raised the bar for beauty, though, it's good to know that the difference between a weedfest and a "really big show" is just a well-timed half hour here and there.

In the photo: late-flowering thoroughwort (white), New England aster (pink to purple) and cutleaf coneflower (mostly seedheads at this point, rising high in back).