Friday, October 10, 2014

Death of a Stream


During my visit to North Carolina last month, my friend Perry took me to see how erosion can destroy a creek. Just last year, there had been a healthy, shallow, narrow creek meandering through this section of a wooded valley. What we found on this visit was a ditch eight feet deep. Trees had fallen as erosion undermined their roots, the ground pulled out from under them. This land is protected--preserved for all time--and yet the stream appears to be self-destructing within the boundaries of this nature preserve.



How this happens is completely counterintuitive. There's no rogue backhoe tearing at the tree roots, no misguided government policy like the channelizations of streams that happened in the 1960s. Though we usually think of erosion as being a process that degrades a stream from the top downward, this demolition starts downstream and heads up. Furthermore, the valley upstream of this section is undeveloped beyond a few scattered homes.

The process at work can be seen in the lower left of this photo, where there appears to be a ledge, a sudden dropoff in the mud. That's what's called a "head cut". As water flows over that ledge, it erodes the face of the dropoff, causing the ledge to gradually shift upstream. The same process is at work on a much grander scale at Niagara Falls, which is slowly but steadily moving upstream from where it was millenia ago. It's like the streambed were a loaf of bread that someone has been cutting slices off of, slice after slice, heading upstream.


How did this process of destruction get started? On the map, there are two branches of a stream that flows northward (bottom to top on the map). At the lower right is I-85. Tens of thousands of people drive peacefully by every day, their ride made smooth and safe by that broad ribbon of carefully engineered concrete. Not one of them is aware that the road, a ribbon of impervious surface, sheds copious amounts of stormwater, which then barrels down the creek, creating enormous erosive pressure. Somewhere miles downstream, the bottom of the creek gives way. A headcut begins, which then "travels" upstream, back towards the source of the eroding stormwater, consuming and deepening the creekbed as it goes.

Though the little branch of the creek on the left of the map, the one we visited, isn't downstream of the freeway, the erosion of the main branch created a headcut that then headed up the smaller branch as well.

We looked at the soil. It was sandy rather than piedmont clay. At this point, Perry pointed out that the headcut was moving upstream so fast--we estimated 200 feet of creek consumed by erosion in the past year alone--because the soil it was cutting through had not been there a few hundred years ago. During the heyday of tobacco farming, the soil that washed off the fields accumulated in the valleys. The stream is actually cutting down through layers of silt deposited during the agricultural era.

This might suggest that the erosion is actually helping the creek return to its historical level, but the result will not be restoration. Even though the creek may end up down near its original level, the valley's vegetation is still perched high on all the silt. The creek has become disconnected from its floodplain. The water table in the valley drops to match the level of the creek, which makes the vegetation more susceptible to drought.

A healthy creek floods easily and often, in the process dissipating energy and watering the surrounding floodplain vegetation. A deeply incised creek floods rarely, so that all that weight and power of water puts erosive pressure on the creek banks, detaching the stream even further from its natural interaction with the floodplain. Aquatic life has a hard time of it when its home is being either eroded away or buried in silt.

Christmas ferns and witchhazel will still grow on the slopes of the valley. But the valley is changed. The headcut has reached a spot where a beaver dam had created a wetland. Chances are, the headcut will undermine the dam and drain the wetland. Yet another example in our world of how cause--the building of an interstate a half century prior--can be so distant in time and space from ultimate effect.

Thursday, October 09, 2014

Humanities and Environment Series Starts Today

The Princeton Environmental Institute is sponsoring a series of panels on "how we can deploy the essential insights and methods of the humanities and arts to tackle urgent environmental issues."

The first panel, today at 4:30 in McCosh 10, will feature prominent environmental historian William Cronon, who gave a masterful talk last night that traced the concept of wilderness from the Bible and 17th century America through to its relevance today as we enter the Anthropocene.

Wednesday, October 08, 2014

A Piedmont Prairie Selfie


Even prairies are taking selfies. What a great looking group. All smiles. They were all decked out, celebrating this special event called "late summer". These plants live in Durham, NC, which is part of the same piedmont as Princeton. Some, like Indian grass, black-eyed Susan, and probably wingstem as well, are found in NJ. One of my favorite native grasses, split-beard bluestem, and something called purple disk sunflower, which isn't included here because it was too busy making seed to join the photo op, show NJ as the northern edge of their range. Another plant that, despite hanging out in seedy places like empty lots, can be a real beauty, is hyssopleaf thoroughwort--a smaller version of a plant common to our area, late-flowering thoroughwort ("late boneset" for short). Like the golden aster in the lower left (Chrysopsis mariana), the hyssopleaf thoroughwort appears to range even further north than NJ, but doesn't show up around Princeton.


Grasses are hard to photograph, but you can see how these fuzzy seeds of split-beard bluestem split off in two directions. Backlit, a patch of this grass has a cottony glow. In Princeton's meadows and along right of ways, we have little bluestem, broomsedge bluestem, and a few scattered specimens of big bluestem, none of which have this ornamental clustering of seeds but which can still be easily identified by their overall appearance.

Also at the site were a blue lobelia,

and Meadowbeauty (Rhexia mariana).

That all these species, plus post oaks, can be found here suggests that this preserved land holds promise for restoration as a piedmont prairie or post oak savanna.

Tuesday, October 07, 2014

Remembering to Celebrate

On a recent trip down the piedmont to Durham, NC, I was handing out congratulations left and right. For starters, there was the fifteenth birthday of the nonprofit I started there in the pre-Princeton years.

While in town, I also congratulated this corn on having grown up to the roof of a two story house bordering one of the urban nature preserves. Giant corn is associated with Jala, Mexico, near Guadalajara, which is towards the Pacific Ocean from Mexico City. Grow enough of this tree wannabe, and you might be able to shade your house in late summer.

There was the incredible shrinking lawn of my friend's neighbor, who each year de-turfs more of his front yard and replaces the lawn with tomatoes, herbs and watermelon.

I congratulated this "rabid wolf spider" (Rabidosa rabida), on producing that promising eggsac, and on being so innocuous despite its scary name.

And this one, for such a fine clutch of baby spiders on its back.

There was an Argiope spider, sometimes called a writing spider or zipper spider, to compliment on its writing ability. If it crosses your mind that it might be the inspiration for the spider in E.B. White's Charlotte's Web, the web says you're right.

And then there was a native Euonymus shrub (Euonymus americana) to congratulate simply on being able to produce its ornamental seeds. This shrub is a favorite of deer, which makes this one's health a testimony to the advantages of nurturing nature in the city.

Friday, October 03, 2014

Charter School Planting Possibilities


I've heard the Princeton Charter School may be rethinking its landscaping. This could be good news for any student wishing to get acquainted with our natural heritage of native species. As things are, there's a tightly controlled landscape of trees and turf, with a few little raised beds for vegetables near the staff parking lot.


One promising spot for a narrow raingarden is this ditch next to a walkway.

The island dividing the parking area from Bunn Drive could accommodate a larger raingarden,



as they did on the Princeton University campus behind the new neuroscience building just off Washington Road. Note the curbcut where runoff from the street can enter the concave raingarden. A little weeding out of the foxtail grasses would neaten up the appearance considerably.

What really would be exciting though, and very educational for the kids, would be to work with the office complex just up the hill from the Charter School to turn this big detention basin into a meadow of native grasses and wildflowers. We're talking about a habitat bonanza for birds, butterflies and other pollinators,

and shifting from weekly mowing, of an area that can get very wet, to an annual mowing.

What could be more educational than to show kids how something negative--polluted runoff flowing from a big parking lot into a detention basin that's difficult to mow--


can be used to feed something positive--a wet meadow that provides beauty for us and food for an endless variety of pollinators?

I have already approached the manager of the office complex on Ewing Street about shifting to meadow, but it was nixed by the owner in Texas. If the Charter School approached them, they might react differently. A federal agency, Partners for Fish and Wildlife, has helped in the past with expertise and materials to shift basins from turf to meadow, such as at Farmview Fields.

This is a very do-able initiative for someone at Charter School to explore. I can supply contact info for the office complex manager.

Wednesday, October 01, 2014

Local PawPaws Ripe


For anyone who hasn't tried pawpaw--our northern representative of a largely tropical family of fruits in the Annonaceae--the Whole Earth Center has some in stock from a local supplier. The harvest only lasts a couple weeks each year, according to one employee. Pawpaws have a short shelf life, and bruise easily, which has long hampered efforts to market them in anything beyond a small scale, local fashion.

I bought one and shared it with my daughter, who had never had one. She said it tastes like a combination of mango and kiwi. Delicious.

You can type "pawpaw" into the search box at the top of this blog to find a couple previous posts on the subject.

Saturday, September 27, 2014

Learning from Harrison Street Park's Plantings

In 2010, after years of planning, Harrison Street Park was planted with an ambitious array of native trees, shrubs and flower beds. The goal was admirable enough: Beautify a park that had until then been largely a static assembly of trees and grass, with little habitat and ornament. I was involved in the early stages, providing a detailed ecological assessment and stewardship plan. Princeton arborist Bob Wells contributed a tree survey pro bono. After this input of local knowledge, an outside consulting design firm based in Philadelphia, was brought in to develop plans for plantings and play equipment, with ongoing input from neighbors.

When the planting was finally done, there followed with uncanny timing a deep drought. Neighbors, having committed to caring for the plantings, put in long hours through the summer. Most of the plantings survived that first, heroic year, but then volunteer energy began to dwindle. A couple very active neighbors moved away. Borough maintenance staff couldn't take up the slack because they weren't trained to care for anything other than trees and turf. A professional weeding in 2013 salvaged some flower beds, though many of the planted species had by then been lost. 


And yet, in 2014, with most of the beds a weedy tangle, two of them are flourishing. This raingarden at the edge of the field is weed-free and filled with flowers.


And this planting next to the bridge dedicated to borough engineer Chris Budzinski still looks good.



Why are they prospering while other plantings have been taken over by Canada thistle, mugwort and other aggressive weeds? The answer lies not in how much money was spent, or the beauty of a design meticulously laid out on paper. In fact, the best results were attained without cost or elaborate planning. Instead, success grew out of on-the-ground experience and long observation of how rainwater flows in the park. That flow, whether natural or manipulated to advantage, determined which gardens survived and which ones burned out volunteers by growing abundant weeds.


When I began my analysis of the park, I began here, in the parking lot for a prominent architect's offices. You can see how this parking lot matters if you turn 180 degrees,


and look downhill towards where all the storm runoff from the asphalt flows into the park. This water is so important that, when they repaved the lot a year or two ago, I checked to make sure they didn't add curb and gutter to divert the water into a storm drain.



Why? Because just beyond the fence is a raingarden that I and other neighbors helped Clifford Zink to plant.

In the park's large expanse of grass, the garden (back right) was planted not just anywhere, but strategically located in a sunny swale that receives the runoff from the parking lot.

The periodic infusion of water creates an underground reservoir of moisture. Powered by adequate sunlight and fed by the stable water supply, the native plants prosper. What few weeds manage to survive the competition can be easily pulled from the soft ground. Now, it might have been better if we hadn't planted sunflower species that spread underground and have been steadily displacing the less aggressive swamp milkweed, hibiscus and even joe-pye-weed. But the result is still attractive and very easy to maintain. A well-timed hour or two with a few volunteers pulling out some of the sunflower stems next spring would restore balance. It's worth noting that this successful garden, planted by volunteers at no cost to the borough, was actually slated to be removed by the landscape design firm, which failed to understand its logic and value. Neighbors had to rally to make sure it was not removed.


Of the garden beds added by the design firm, only one has proven relatively easy to maintain, due to it also having been planted in a swale, where wet, sunny conditions favor the natives and make weeding easier.


This shadier planting might have done well with consistent care, but long periods of neglect allowed garlic mustard and Canada thistle to take hold. Apparently worked on this year by parks staff led by someone knowledgeable about plants, it still contained enough of the original foamflower and ironweed to be attractive.




There were other locations in the park with the combination of wet and sunny conditions that favor native wildflower plantings, but these spots were instead planted with trees that cut off sunlight, or raised up in a way that shunned the periodic infusions of runoff that could have keyed their survival. The flower bed in this photo, shaded and raised up on a berm, must have looked good on paper and when freshly planted, but offered none of the sun and natural water needed for the natives to compete with weeds. These berms, hazardous to mow, can't even revert to lawn as most failed gardens do.

So, what's the verdict on Harrison Street Park's grand experiment in planting and caring for naturalistic flower beds?
  • Study the way water flows in the park and choose your spots wisely. A poorly situated garden that favors weeds over intended plants will burn out volunteers.
  • Rather than plant traditional perennial borders that tend to be elevated and attract weeds, focus on areas that are in swales or depressions, and receive enough runoff and sunlight to power native floodplain species robust enough to outcompete unwanted plants.
  • Start small and expand incrementally, making sure that the maintenance work doesn't outstrip volunteer interest.
  • Particularly in a place like Princeton, use local talent that feels invested in the park. If a design firm is needed, favor one that understands how water drives landscape decisions, and has had as much experience maintaining flower beds as designing them.
  • If town maintenance crews are used, have them supervised by someone trained in plant identification.

This photo captures what has worked well in the park: two rain gardens and the sports field intentionally given a slight crest to shed water. These successes, whether designed to receive runoff or shed it, depended on close attention to "where the water goes."

Tuesday, September 23, 2014

Summer's Last Florrah


In the backyard, the exuberant yellows and brilliant whites of August are mellowing into a more subtle color scheme. The stonecrop, which I'd like to induct into the nativy non-native club, is deepening towards burgundy.


The sunchoke, aka Jerusalem artichoke (Helianthus tuberosa) is showing up late for the party and wondering why so many others

are sporting sober earthtones.

September's late boneset (Eupatorium serotinum) is gracefully extending the white of August's boneset (Eupatorium perfoliatum), though to a much reduced audience of insects.

Goldenrods and New England aster are brightly colored, but

their cheer is muted by the deepening browns of Joe Pye Weed.

Today was as good a time as any to take a measure of this magnificent summer's growth. Cutleaf coneflowers rose to 6.5 feet. The JoePyeWeed topped out at 8.5 feet. The cup-plant in this photo rose ambitiously to 9.5 feet before growing top-heavy and splaying out.

Sunchoke was the undisputed champ, rising to 10.5 feet, even though it was growing in pots.

The big pots, which contain the sunchoke roots' imperialistic tendencies, can be tipped over in the winter to harvest the edible tubers packed inside them. (Idea: Try cutting the tops when they die back, turning over the pot, then lifting the pot occasionally to take a few tubers.) I eat them raw, but a friend heaped praise upon sunchoke soup.

School Garden Tour Sunday


Here's an opportunity to visit some of the great school gardens in the Princeton area. Info below's from Liz Cutler of Princeton Day School. OASIS stands for Organizing Action on Sustainability in Schools.

Reserve your spot now for this Sunday's OASIS School Garden Tour. We will visit the school gardens at Princeton Friends School, Community Park School in Princeton, and the Lawrenceville School Farm program, touring the gardens and hearing from the garden coordinators about curriculum integration.

Meet at Chapin School on Princeton Pike by 12:55 in time for a 1pm departure by bus (donated by Chapin School). You must reserve a spot on the bus. The tour is free. We will return to Chapin School at 4:10pm.

To reserve your space or for more info contact, Liz Cutler: lcutler@pds.org

Tuesday, September 16, 2014

Two Bees, Two Styles, One Flower

These are two very brief videos that show how two different kinds of bees--a bumble bee and another kind much smaller--get food from a richweed flower in completely different ways. The bumblebee goes for the nectar, while the small bee in the second video climbs out on the long filament to get to the pollen-bearing anther, ignoring the rest of the flower.

I couldn't find anything online elsewhere showing this behavior, and I can't speak to whether it's common for one flower to accommodate the differing needs and capabilities of different types of bees in such a contrasting way. Richweed (Collinsonia canadensis) is also called horsebalm or stoneroot. This quote from a previous post about richweed goes well with the first video:
"Bumblebees look perfectly matched for this flower, bobbing from one to another, giving each one a bear hug as they sip the nectar. The flower is so shaped, with the stamens jutting out on either side of the flower, to appear as if the embrace is mutual."
The first video I took while talking to a friend next to our front yard raingarden.



Then along comes another kind of bee that relates to the flower in a completely different way.

Sunday, September 14, 2014

Boneset Days -- A Pollinator Bonanza

Update, August 2019: Someone who goes by the name Beatriz Moisset was nice enough to identify some of the insects below that I found on the boneset flowers in my backyard. I have integrated her ID's into the text.

If it's early September, it must be time to write about what I did with my summer. In August, I traveled once again to the land called Boneset. What I saw there will open the minds of anyone who thinks flowers are only visited by honey bees and butterflies. In the land of Boneset, which happens to be at a perfect height for photographing, miniature acres of tiny white flowers attract all sorts of wonderfully strange creatures whose names are on the tips of very few tongues. Some six-legged visitors are interested in what the flowers have to offer. Others, often with eight legs, lay in wait, using the flowers as bait to attract their next meal. Some linger for days, others patrol without landing. Others are said to leave their scents, then check back later to see if the scent has attracted a potential mate. Some arrive in sufficient numbers to look like herds of insects grazing in a field of brilliant white. Others multi-task by continuing to feed on the nectar while they mate.

Here is the first wave of photos from my travels. Say the magic words, "Eupatorium perfoliatum", plant one or many in your backyard, and you too can travel to this unsuspected world.


#1) There's a tiny, spiny creature reminiscent of a lobster,

#2) and the inchworm mentioned in a previous post that includes what some might call a spellbinding video of it doing its inchworm walk.

#2a) Is this the same inchworm (camouflaged looper), but tinier and wearing a slightly different camouflage? I'm glad you asked because I have absolutely no idea. I can tell by the markings, however, that the forefinger in the background is definitely mine.

#3) And this chunky fellow wearing orange and black. What year's Princeton alumni coat is that? Class of 2 million B.C., perhaps.

Okay, I really should be giving these insects their real names. All in the fullness of time. Many likely don't have decent common names. We'll need to have a contest.

Again, our commenter to the rescue: "a wedge-shaped beetle, looking for bees to parasitize their nests."
The link says it's in the family Ripiphoridae, lays its eggs on the flowers. The eggs hatch, and the larvae hitch a ride on a bee or wasp, then does its parasitizing back at the host's nest. All sorts of mischief going on here, on these pretty little flowers.

#4) Nice cape, or are those tails?

Our commenter says it's a net-winged beetle. The genus is Calopteron in the family Lycidae. Its larvae feed on insects and other arthropods under bark. So, I guess it can be considered a biocontrol, 

The adult's "aposematic" colors warn potential predators that they are poisonous. They lay their eggs under the bark of dead or dying trees, and the larvae eat other insects there. In other words, they participate in the food chain that is part of the long afterlife of dead trees.

#5) These bugs ("bug" in entomology actually refers to a kind of bug, an order of insects called the true bugs--I know that much), from the frequency of their appearance and the frequency of their coupling up, appear to consider boneset their home as well as their lunchstop.


#6) This one looks a lot like the previous one, but it's skinnier and appears to have swollen, clawlike legs in front.

#7) Finally, something familiar: A honey bee, which is what most people associate with flowers. And wouldn't you know it? That's the one that happens not to be native to America.

#8) For these nondescript black bees, my classification for the time being is small, smaller, tiny, and miniscule. The slogan for this blog post is "Miniscule is cool."

#9) The pattern of stripes on the abdomen has GOT to be a clue.

Note: A commenter says this is a "bee wolf" (Philanthus gibbosus)--a wasp that preys on bees to feed its young.

#10, 11) This photo and the next may be of the same kind of black wasp, but the first one looks hairier on the thorax.



#12) Here's a sweat bee, which rhymes with Halictidae. With a name like that, it must be attracted to sweat, or at least the salt in the sweat. Does boneset sweat? It sweats nectar.

Note: a commenter says it's a cuckoo wasp, in the Chrysididae. Like the cuckoo bird, it's a parasite that lays its eggs in the nest of other species.


#13) This might be another kind of sweat bee.

Note: Our very helpful commenter says this is a long-legged fly in the Dolichopodidae family. They are said to have elaborate mating behavior, during which the male displays its long legs for the female.


#14) And this, which begs the question:

How much sweat could a boneset sweat if a boneset could sweat sweat?

#15) This one has such a "tinier than thou" air about it.

Note: Our commenter says it "looks like a parasitic wasp. Great biocontrol!"





#16) There, down in the lower left, something brown that looks like a fly, but its wings stick straight out to the sides.

Note: our commenter says it "looks like a Tachinid fly, difficult angle. looks like this one http://bugguide.net/node/view/300648
(Tachinids can help control insect pests in gardens, by laying eggs on them that hatch and then consume the pest. At this link you can scroll down to see the Tachinid's eggs on the host insect.)


#17) This little fellow, oval and black, reminds me of a small, tank-like insect that was attracted to the salad when we ate dinner outside when I was a kid in Wisconsin. Maybe if we had planted more boneset, they would have stayed out of the salad.

There you have it. I counted 17 that are plausibly different species. And that's just on a sunny afternoon on August 7, with the boneset just starting to open up in a backyard behind a house on a busy street in Princeton, NJ. This "What I did with my summer" essay is starting to look like the first chapter of Boneset Days, or the soap opera As the Boneset Blooms, with a cast of characters that may grow to rival a Russian novel.