The Lost Forest of Rogers Refuge

This past November, I received a request to look at a lost forest in Princeton. 

The request came from what may be the oldest open space organization in town--the Friends of Rogers Refuge. Dating back to 1967, FORR has been working with the town, and the water company that owns the land just down from the Institute Woods, to sustain the refuge's role as premier habitat for a tremendous diversity of birds.

Over the years, I've been able to witness and collaborate with a progression of leaders who have overseen stewardship--the Southerlands, Tom Poole, the Spars, the Varians, and most recently David Padulo. 

At annual meetings, discussions have tended to focus on the refuge's central feature, the surprisingly extensive marsh--how to keep it wet enough and protect it from the super-aggressive Phragmitis.

But this year, concern now extends to the floodplain woodlands surrounding the marsh--also vital bird habitat. One of these woodlands, thriving four years ago, has lost its trees.

This was not a forest classically lost to logging. The trees were not cut down but rather strangled over the course of several years, then left standing, each tree a monument to its past life. 

Few have seen the now ubiquitous strangler, the Emerald Ash Borer accidentally introduced to the U.S. from Asia. It's larvae work quietly under cover of bark, feasting on the ash trees' circulatory tissues. 

That a whole forest could die speaks to how common ash trees once were. The most numerous tree in Princeton up until just a few years ago, comprising more than 10% of the tree cover, the ash tree's skeletons can be found throughout the canopy of residential and open space lands. Ash were particularly good at colonizing abandoned fields, to the point of dominating one area of what is now Rogers Refuge. 

As the botanist in an organization of birders, I was asked what the longterm prognosis for this lost forest might be. Winnie Spar, Joe Melton, and I walked the red trail to have a look.

One striking feature is what I call "poison ivy trees." These are dead trees, still standing, that have been scaled by poison ivy vines, with their classic "hairy is scary" stems. In order to bloom, poison ivy must climb a tree, sending out lateral flowering shoots along the way. The branch-like laterals give the tree the look of still being alive, even though all the leaves are now poison ivy. The flowers produce berries that, birders will enthusiastically tell you, serve as important food for birds.

Another feature of a lost forest is the shrub growth that now thrives on the infusion of sunlight previously claimed by the tree canopy. Much of this shrub growth, unfortunately, is nonnative and inedible to wildlife, like this Asian Photinia. At least it can be said that the invasive shrubs are not as thick at Rogers Refuge as they are at the Institute Woods just up the hill.

A few other native tree species fill a small portion of the void. In early November, the occasional silver maple and pin oak still had many of their leaves. Mixed in were a couple elms, and a red maple. 

Used to the numerous red maples at Herrontown Woods on the other side of town, I was surprised to find instead an abundance of box elder of every size growing in this broad floodplain of the Refuge. Related to maples, box elder are not the most statuesque of trees, but their soft wood can make good bird habitat. They now stand as the main hope for rebound in this patch of former forest. 

The walk being with such knowledgeable birders, attention never strayed far from bird life. We saw a couple pileated woodpeckers, a coopers hawk and a couple other larger hawks. Winnie kept up a running monologue about the status of this or that bird. Mockingbirds have been around for a long time, but the catbirds keep them out of their territories when they are present. While a warming climate is causing many birds to extend their ranges northward, ravens, surprisingly, are moving south. She's seen some in the Refuge. Warblers love something about the spicebush flowers, whether it's the flowers themselves or an insect in them. Blue gray knatcatchers were mentioned, along with many other bird names that didn't register in my botanical brain.

There's a lot of concern that last year's fires in Canada have been very hard on migrating birds that nest up there. A woman who catches and tags migrant birds had been having very few birds coming back down from Canada, but her catch/tag/release activity, conducted on Sundays, was hampered by rains every weekend this fall. One day she got only ten birds, total. 

But then Winnie is quick to add that she saw Cape May Warblers in the Refuge for the first time, several in fact, with immatures, and they too nest in Canada. Winnie is one to accent the positive, while acknowledging that migrant bird numbers are down 50-90%. 

This lost forest, the decline in bird numbers, accelerating changes in climate, democracy under threat--in many ways, America is losing its memory of what it once was. The soil, for its part, holds memory through the seeds that remain dormant within it. Back when the seed bank--this stockpile of seeds yet to sprout--was dominated by the seeds of native species, succession as an ecological phenomenon featured an orderly and predictable progression of species, from grassland to shrubland to mature forest. But the soil under our feet has lost its memory, whether by plow, development, intense browsing, or displacement of native species. Invasive lesser celandine, poisonous to wildlife, coats the ground in the spring, followed by inedible stiltgrass and its billions of seeds in late summer. Invasive shrubs and deer combine to limit native species and thwart the once timeless process of succession. Though the tree canopy is still dominated by natives, these are under increasing attack from introduced insects and disease.

Even healthy trees can be overwhelmed by vines of porcelainberry and wisteria.

Given the circumstances, it's fair to ask what sense there is in persevering. What I find is that the native growth force, if often smothered and badly abused, remains intact. When given a chance to prosper, native plants and wildlife still can thrive. In Rogers Refuge, we've seen a tremendous rebound of spicebush since the town began culling deer to reduce browsing pressure. That in turn has improved habitat for birds. FORR has paid contractors to successfully set back the Phragmitis and porcelainberry. 

Through periodic interventions over a number of years, the Varians have virtually eliminated the one patch of invasive Japanese knotweed at Rogers Refuge. 

We pick our spots, time our interventions strategically to have the most impact for the least amount of effort, and look for opportunities. Despite the tragedy of losing ash trees, the new openings in the canopy could potentially allow native shrubs to grow, flower and bear in ways they haven't since being shaded out decades ago. 

Our inherited environmental mindset is that nature, if protected from intentional depredations like logging and draining, will heal itself. As FORR's webmaster Laurie Larson points out, "when Charles H. Rogers and the Southerlands started birding the “Water Company” in the 60s and 70s it was a landfill." The initial fight was to put an end to dumping. But now, at Rogers Refuge and many other places, the main depredations (invasive species, climate change) are unintentional, and the healing must be helped along by intentional effort. That effort could seem a sacrifice, but the primary feeling is one of gratitude, for the chance to work with nature--the greatest and most generously creative collaborator of all. 

The Pleasure and Aesthetics of Native Seed Collection

One of the more pleasurable and aesthetic outdoor experiences in the fall is gathering seeds. I claim no expertise, but adhere to one simple rule: let the stem below the seeds turn brown before harvesting. And harvest when the seeds are dry. Also, be messy. Let some of the seeds fall where they would have fallen if you hadn't come along to take some. Alright, that's three rules. But that last rule is especially enjoyable. How many times in your life have you been told to be messy? 

There are more official rules out there for seed collection, particularly of uncommon species, but nearly all the seeds I collect now are either from my backyard or the Botanical Art Garden, both of which I planted. It's gratifying to see these new populations of local genotypes thriving, and to expand their local presence further. 

The plants I harvest from tend to be generous towards a human tendency to procrastinate. Many species hold on to their seeds for months in the fall and into the winter. But the prettiest time to be picking them is sooner rather than later, as they become increasingly weathered and threadbare as winter progresses.

Harvest of wild senna, seen in the first photo at a lovely stage when the leaves contrast with the dark seed pods, can be postponed considerably, as the pods hold onto the seeds for months.

The bright, fluffy clusters of ironweed seeds are easy to identify on stems that can reach 8 feet.

Rose mallow hibiscus (Hibiscus moscheutos) holds its seeds in convenient cups. Best not to wait too long, because there's a slow attrition to spillage and insects as winter sets in.

As with other sedges, the seed clusters of morning star sedge (Carex grayi) will break apart as fall progresses. Some other local sedges with easily collectible seeds are squarrose sedge and fringed sedge.

The seeds of bottlebrush grass, attractively arranged along the stem, were already starting to fall off when I collected them in late October. Just grab the dried stem between thumb and finger and pull upward to strip the seeds. This is an attractive understory grass. 

The seeds of turtlehead (lower left in the photo) are still ripening, having shown their own form of procrastination, waiting until early fall to bloom.  

Collecting seed has extra meaning and purpose this fall, because many of them will be planted along a wooded slope in Herrontown Woods where a large clone of wisteria had pulled down some of the trees, creating openings where sun can reach the ground. Years of effort, particularly with the consistent, transformative work over the past year or two by volunteer Bill Jemas, has largely snuffed out the daunting wisteria clone that had taken over an acre or two, choking other growth as it steadily expanded along this broad hillside. It even somehow traversed the creek and was headed towards the Botanical Art Garden, adding another layer of urgency to knocking it out. Into the void created by our wisteria removal has come garlic mustard and stiltgrass, but this year we pulled those before they went to seed. 

With much of the slope now bare (the photo shows wisteria to the right, cleared areas to the left), it's time to introduce native plants. We could toss the seeds hither and yon, but I like to give them a better chance by being more deliberate. Deer are an issue, of course, given their appetite for native plants, and my plan is to plant seeds in small circles here and there, creating loci a couple feet wide. I like to scrape a thin layer of dirt away, scatter some seeds, then sprinkle some dirt on top and tamp it down. Then I'll place a 3 foot high plant cage around each circle. Those that grow inside the cage should be protected enough to mature and produce seed that can then scatter beyond the cage on its own in subsequent years. 

It's actually a good way to find out which species the deer leave alone, and which they munch on. We are, in a way, creating "deer feeders" by protecting a few plants inside the cages--plants that each year spread beyond the cages, where the deer can eat them. This approach has been successful at the Barden. Thanks to the town's investment in annual deer culling, many of the plants that sprout beyond the cage survive. 

Of course, all of this thus far is talk. Procrastination is a particularly powerful factor when it comes to getting plants or seeds in the ground. There's so much other work to be done! What's real and lovely, and has actually happened, is the seed collecting. 

Last Chance to Pull Stiltgrass

This week and maybe next are your last chance this year to pull stiltgrass (Microstegium vimineum). This mega-invasive is an annual, so the logic of countering its spread is to pull it before it can produce and drop seed. If the seeds haven't loosened yet at the end of the stalk, you can still pull it. Throw it in the trash, or if there's a lot, make a big pile of it so that any seeds that sprout the next year will all be in one place and easily covered or pulled. Definitely don't put it in your compost if its seeds are forming. If stiltgrass is just starting to invade your yard, pulling as completely as possible now will greatly limit its seedbank for next spring. Another strategy for large stands is to let the stiltgrass grow, then just as it begins to flower mow it short and hope its feeble roots don't have enough energy to grow another flowering stalk. 

For those fuzzy on identification, google lots of images, and look for the silver line running down the middle of the leaf. Stiltgrass can grow in the shade or sun, climb up to four feet, or thrive in a miniature state while ducking below your mower in the lawn. It's incredible survival skills include being incredibly inedible for wildlife. Stiltgrass gives nothing back to the habitats it increasingly dominates.

More on Stiltgrass, and a Success Story

Walking in the local woods, you've probably seen this kind of scene--what looks like a grassy meadow extending through the forest. In the filtered light of the understory, its simplicity and lushness may have some visual appeal. And yet, in some ways what you are looking at is the ecological equivalent of an urban food desert. 

Stiltgrass is an introduced plant that could be called a pervasive invasive, able to thrive most anywhere and dominate whole landscapes. Its success has come in part through being inedible. As wildlife selectively eat native vegetation, the stiltgrass expands, preventing the native plants from rebounding.

Unlike another nonnative annual weed that can look similar, crabgrass, stiltgrass becomes ubiquitous because it can thrive in sun or shade. That means the stiltgrass invading your lawn and flower beds can continue spreading ad nauseum into the nearby forest, or vice versa.

We used to call it bamboo grass--something in the shape of the leaves is reminiscent. The stiltgrass name refers to its angular growth, with each segment supporting the next as it climbs up and over fallen logs and other plants. Packing grass is another common name, referring to how it was once used to pack porcelain for shipment. That's probably how it first reached the U.S., in packing crates sent to Tennessee. 

When I first encountered it, growing on the bank of Ellerbe Creek in Durham, NC, I thought it graceful. Then came Hurricane Fran, bringing floods and fallen trees. In the aftermath of that massive disturbance, stiltgrass exploded in the landscape, expanding and ultimately choking forests with its vast, dense stands. New Jersey proved no different. 

Stiltgrass tends to establish itself along roadsides. Here it is growing in a green ribbon along Herrontown Road. Trails, too, provide an avenue for extending its reach, its tiny seeds carried on boots or the hooves of deer.

Though stiltgrass has covered large areas of woodland in the eastern U.S., we have found it worthwhile and even satisfying to counter its relentless incursions. Today in the Barden at Herrontown Woods, some volunteers pulled it out of a patch of native jewelweed along the edge of the parking lot. 

Nearby, on land where we have largely eliminated a massive clone of wisteria, stiltgrass was starting to move into the void. If nothing were done, this open woodland would have become a pasture of stiltgrass. But we have acted early enough to be able to remove all of this year's stiltgrass, dramatically reducing the seeds available for next year's crop. This photo shows the last patch before we pulled it. 

Interestingly, there are native grasses that look a little like stiltgrass, the main one being Virginia cutgrass (white grass), Leersia virginica. It has longer, narrower leaves that lack the silver stripe down the middle. As is a common ecological refrain, the native grasses "play well with others," not forming stiltgrass's massive, exclusionary stands. Some smartweeds like Lady's Thumb can also bear a resemblance. 

Wisteria Contained

As a land manager, having fought back many a runaway acre of wisteria in a woods, tangled with and been tripped up by its myriad tanglings, even walked upon the tranpoline-like, crazy quilt its runners can weave above the ground, I can still feel amazement when witnessing a wisteria molded by intention--first at its abundant flowering, and second, that someone has managed to keep its wanderlust in check. 

This house is a couple doors up from Hamilton Ave. on Linden Lane. Similar displays are likely in progress on the front porch of Morven and at Marquand Arboretum. They hearken back to an era when people had the time and interest to tend to their gardens, when gardening was a relationship, and gardens had personalities. My parents had such a garden in Ann Arbor, MI, where I would trim the wisteria growing up their patio trellis. The flowers were pretty, but never reached the magnificence of this display on Linden Lane.

The wisteria in this photo is thankfully in the front yard, along a town street. If the owner ever lost interest in carefully maintaining it, there's no nature preserve nearby for the wisteria to swallow, only the house and the neighbors' yards. Having witnessed and reckoned with the unintended consequences of inattention, I can see both the beauty and the Burmese python-like potential lurking within, its expansionist nature for now contained.

Related posts:

Where Vines Tackle Trees: A wisteria that grew so thick you could walk on its web of runners without touching the ground. 

Another Perilous Embrace--Wisteria and Horse Chestnut: When wisteria gets loose in a neighbor's yard.

Wisteria's Tamed and Wild Twinings

The front porch of Morven has an educational feature for gardeners.

Go to the right side of the porch and witness Chinese wisteria twining up and to the right. 

Go to the left end of the porch and witness Japanese wisteria twining up and to the left. 

This contrast in twining direction appears to be a thing. There's agreement that the two species twine in opposite directions, but disagreement on how to describe it. The Japanese wisteria's winding up and to the left is described as either clockwise or counter-clockwise, depending on the website. The two websites I happened upon agree, however, that the direction of twining is not determined by whether the plant evolved in the northern or southern hemisphere. This is disappointing, as I had hoped for a pattern, which would be all the more satisfying if it happened to match the direction of swirl when water goes down a drain. Alas, some other force must be at work.

What Morven's porch won't show you is just how aggressive wisteria's twinings can become after a garden is abandoned. To comprehend the scale of expansion, you would need to travel to Herrontown Woods, where the extent of a wisteria clone (Japanese by the look of its twining) is still apparent in the woods. There are two clones, both covering more than an acre each. At their exuberant zenith, they had grown up and over trees and rendered the ground a monoculture of their foliage. One clone, up at Veblen House, is now mostly vanquished, in large part due to the extraordinary persistence in years past by Kurt and Sally Tazelaar. The success of that work depends, however, on ongoing vigilance to cut any sprouts still rising from the remnants of its sprawling root system. 

We are still very much in battle with the other clone, however, across the stream from the Barden. Each year for about four years now, the town has paid contractors to spend a couple days each summer applying systemic herbicide to this or that side of the monster. The herbicide is absorbed and translocated down, to weaken the wisteria's massive network of roots and runners. I think of it as comparable to the medicines we use to maintain our own health, well targeted and no more than necessary. 

Then, this past fall, a volunteer named Bill Jemas (posing in the photo with a wisteria vine) contacted the Friends of Herrontown Woods, looking for a good project to give him the equivalent of a workout in the gym. He came several times a week for much of the fall, working largely on his own, checking in with me periodically with a question or two. Cut, cut, snip, snip--he took on the still very intimidating tangle with hand tools and perseverance, making the hillside navigable once again, dotted with piles he made of the cuttings. He then announced his family was headed to Florida for the winter. Reportedly returning this spring, his contribution to the battle has already given us hope that the wisteria monster will not eat the Barden, towards which it was headed, and can be subdued like the one at Veblen House, so that we need only snuff out a few stray sprouts each year. 

A couple related posts:

Another Perilous Embrace--Wisteria and Horse Chestnut : About the horse chestnuts near Morven, and the horse chestnut that was getting overrun by wisteria in front of the 1755 house at 145 Ewing Street. Why does one often find a horse chestnut growing near a historic house? Because they bloom around Memorial Day?

Trees and Thunderbolts : The puzzling story on the Morven grounds of how a thunderbolt killed not the tree it hit, but the tree next to it.

Coyote Spotted at Princeton Battlefield

 A coyote was spotted at Princeton Battlefield this past Friday, March 24. 

Thanks to David Padulo for sending around this photo of the beautiful animal. 

At the time, David (hopefully not the coyote), was on his way to Port Mercer "to check off a Mercer County Life bird (Tundra Swan)," and so happened to have his camera. Port Mercer, for those like me who would assume there aren't any ports near Princeton, turns out to be just a couple miles upstream: the historic settlement where Quaker Road crosses the canal. According to David, the tundra swan was off track, a half hour away from where they are more typically seen, at Assunpink in Monmouth.

As an avid birder, David has taken an interest in Princeton's birding mecca, Rogers Refuge, and now leads the Friends of Rogers Refuge. David, shown here carrying a wood duck nest to a more auspicious location, represents a new generation of stewardship at the Refuge, taking over from Lee and Melinda Varian, who have done so much to keep trails open and control invasive species. 

Turning 83 has not deterred Lee from wielding a chainsaw to maintain the refuge. After meeting with David to discuss how the refuge's marsh might hold more water (a lot of water drains out of the refuge where this photo was taken), Lee and I spent a highly productive hour cutting a clone of wisteria vines that has been growing up and over some trees. If left to grow and expand, the wisteria would eventually swallow the forest surrounding this remarkable marsh. The nonnative wisteria can expand without restraint because there isn't the equivalent of a coyote to keep it within bounds. 

August Nature Vignettes

Herein lie a series of mid-summer encounters with nature in Princeton. 

At the Barden in Herrontown Woods, where artistic photos of native plants ring the gazebo, a tiger swallowtail butterfly was caught imitating art imitating nature. Each of the 30 some wire cages harbors a different native wildflower. This one is clustered mountain mint, which is a magnet for pollinators.

Up near Veblen House, sawfly larvae chowing down on a young hazelnut's leaves adopted an S-shaped balletic pose when disturbed. Imagine everyone in a cafeteria standing up and adopting the same yoga position as you entered. With 9 pairs of prolegs, the sawfly larvae are not true caterpillars, which are defined as having only 6 pairs.

The sawflies' choreographed response is similar to that of a real caterpillar called a contracted Datana seen three years ago on lowbush blueberries also growing at Herrontown Woods. 

If you see the top of a lovely young eastern white pine suddenly turn brown, chances are that white pine weevils have paid a visit. The adults overwinter in the leaf litter, then emerge in spring. The females lay eggs in the central stem of the white pine, the larvae then eat the inner bark of the pine, cutting off the flow of nutrients to the terminal stem. 

In late July and early August, the adults emerge via small holes in the bark. The weevils are native, and the pine survives by using one of its lateral shoots to continue upward growth. Evidence of past attacks by weevils can be seen in a pine tree's crooked stem. 

Why is this gangly weed being left to grow in an otherwise groomed suburban lawn? It's a chicory that has worked its way into the heart of the homeowner by fielding an array of attractive flowers through most of the summer. The blooms of the homeowner's frontyard roses and Rose of Sharon shrubs come and go, but the chicory keeps delivering.

The flowers have a delightful shade of blue that lifts the spirit. There's a fun post about a chicory that grew gloriously out of what looked like pure concrete six years ago at a busy intersection, drawing photographers, including me. 

Liking the plant, I'd like to think it "plays well with others", that is, does not become invasive and exclusionary of other plants in the manner of mugwort or Chinese bushclover. But while traveling recently in southern Wisconsin, I did see it thickly established along a lengthy stretch of country road. But a road embankment is an altered soil that often becomes colonized by nonnatives that aren't necessarily invasive in a prairie.

I was impressed to see that this gardener on Valley Road had vanquished the Canada thistle that had pushed up through the mulch earlier in the spring. (See Weeds That Launch an Underground Insurgency.) A garden tells little of the past battles waged to create this gentle scene of coneflowers and black-eyed susans. 

A meadow needs to be weeded like any garden. Sometimes, the process of weeding, by getting us out there, leads to discoveries and a deeper appreciation of the area being weeded. Scott Sillars and I were weeding the meadow next to Veblen House recently, pulling every Chinese bushclover we could find before they could bloom and go to seed, when I discovered a plant not previously known to bloom there. 

Rose Pink (Sabatia angularis) is a biennial in the gentian family. I had been content to call it Meadow Beauty until I took a closer look and realized it has five petals instead of four. 

Another small treasure, found while cutting invasive wisteria vines in a thicket of privet shrubs near Veblen House, was an antler. It's said that shed antlers are rarely encountered because their minerals make for good gnawing by mice and other animals. This one, however, was in good shape long after being shed over the winter. 

When rains are plentiful, sensitive fern can form robust, expansionist stands that make the name seem a misnomer. But the plant lived up, or down, to its name when this summer's drought turned lush green leaves dry and brittle. 

Jewelweed is another example of a native plant that can be robust in wet weather, then get laid low by drought. A couple years ago, there were so scarce in the Barden at Herrontown Woods that we thought of helping them to spread. But the few specimens cast their spring-loaded seeds far and wide, leading to current abundance.

A lot of native wildflowers have "weed" in their common name, despite their positive attributes. Jewelweed is a good example, with its tubular orange flower that attracts hummingbirds, yet its capacity to become prolific can turn it into a weed in our perceptions.

Pokeweed is another native that can overgrow its welcome, looking sometimes elegant, sometimes gangly. More about pokeweed elsewhere on this blog, including its close relative in Argentina that looks like a tree but isn't. 

 

If you like pokeweed but find it gets way too big, you can cut it down in midsummmer, then watch it regrow in a smaller version of itself that might fit the allotted space better. This works with other tall native perennials as well.

Those who leave Princeton in August are missing out on bur season. If you find your leg covered with burs, it could be that you just walked by some stickweed. 

Here's a better photo. It's one of the plants written more about in a post called Deceptive Weeds. 

White avens is another weed that produces burs. 

If you get tired of watching paint dry, you can always drive down Route 206 towards Montgomery and watch Phragmitis reed slowly eat the road. 

You could also watch the condensate drain away from air conditioning units. Water can be pretty exciting to a gardener in the middle of a drought. Air conditioners pull moisture out of the inside air and release it outdoors. The trick is to take advantage of this water and direct it towards plants that desperately need it during hot, dry days when air conditioners are running the most.

One advantage of composting your food scraps in your yard is the surprise plants that sometimes appear among the moldering banana peels and crushed egg shells. This is a volunteer avocado growing in a Wishing the Earth Well composter.  

A friend of mine potted up one of his compost pile avocados and it's now almost too big to get out the door after a winter spent indoors.

There are a lot of native plants that show their beauty in midsummer when many people are out of town. One favorite of mine is woolgrass, which really should be called brown wool sedge, because it's a sedge, not a grass. You can call it Scirpus cyperinus if you want to sound impressive. Most sedges mature in the cool months of spring, but woodgrass develops more slowly, sending up a tall inflorescence that is attractive at all stages on its way to looking wooly.

It's been a great year for wild senna, a legume that folds up its leaves at night.

When many of the midsummer native wildflowers are looking spent, autumn Helenium unveils an array of attractive yellow flowers.