Coming in March: Three Princeton Adult School Classes at Herrontown Woods

Through the Princeton Adult School, I will be leading or co-leading three classes at Herrontown Woods this March. Classes meet on Saturdays, 10-12. 

To sign up, scroll down through the list of Tours and Nature Walks being offered this spring by the Princeton Adult School. Discount available if you sign up for all three.

Class Descriptions

March 2: The Herrontown Woods Experience: Hiking and Exploration (Princeton Ridge Geology and Magnetic Rocks) - Why do magnets stick to some of the rocks in Herrontown Woods?Hydrogeologist Jon Johnson discovered magnetic rocks in Herrontown Woods and tracked them back to the mother lode. We will retrace his journey, learning about the Princeton ridge's surprising geology and ecology along the way.

March 9: The Herrontown Woods Experience: Hiking and Exploration (Signs of Early Princeton Along the Ridge: Quarries, Smallholder Farms, Timber Harvest) - The mix of nature and culture at Herrontown Woods provides a window into the past. Hidden in what today is a forest are clues to a time, a century ago, when Princeton's ridge was a patchwork of small farms, woodlots and quarries. Participants will learn to recognize these clues, and the history behind them.

March 16: The Herrontown Woods Experience: Hiking and Exploration (Salamanders and Frogs in Herrontown) - Herrontown Woods is a center of amphibian life along the Princeton ridge. We'll visit some of the vernal pools where frogs and salamanders gather in the spring to lay their eggs, and learn about their varied life cycles, as well as efforts to help them survive road crossings during spring migration.

Encountering Old (Plant) Friends at Fairchild Tropical Botanical Garden

Among the many surprising encounters we had during a visit to the Fairchild Tropical Botanical Garden--during a holiday spent in Coconut Grove, more than a year ago now--was the opportunity to sit down and have a chat with the celebrated writer and conservationist Marjory Stoneman Douglas. She's aging well. After a brief bout with death in 1998, by which time she had reached the age of 108, she still looks to be going strong 25 years later. Sitting alone on a bench, she looked like she wanted company, perhaps to tell me about her seminal book, The Everglades: River of Grass, and how she helped found the Fairchild Gardens.

Walking the paved trails that wind through 83 acres, I felt suffused with a bloom of happiness. Maybe I was empathizing with all the happy plants. In Princeton, things can be bleak in winter, but even in summer there is evidence everywhere of trees dying back due to introduced insects and diseases. This patch of Florida is by comparison exuberantly florid. 

Or maybe it was the endearing mix of impeccable and casual, which perhaps reflects the Garden's varied founders, who range from an accountant/businessman to a worldwide explorer to environmental advocates like Douglas. The grounds are at once formal and informal. Paved trails have imprints of leaves and fruits. Encountering no clear route from the parking lot to the visitors' center, we ducked through a shrub border. The lawns are manicured, and yet the plant labels are low-key, well-aged and aging well. 

Structures range from  a sophisticated greenhouse hosting tropical plants and myriad butterflies to this authentic-looking thatched roof pavilion. 

Along the winding paths, there were old friends, like this thriving ombu. Lacking true wood, it is really an overgrown forb masquerading as a tree. I first encountered it in Argentina, where stories tell of it giving shelter to gauchos out on the pampas. Its latin name, Phytolacca dioica, shows it to be in the same genus as our pokeweed. If you saw it blooming, as I did once in a park in the Recoleta neighborhood of Buenos Aires, you might think you're looking at a pokeweed 50 feet high.

How often do we get to see a baobab tree, and a massive one at that? 

Witnessing this assemblage of plants from around the world stirred all sorts of memories of past travels. This tree reminded me of a hike up into the hills outside Medellin, Columbia, in 1974, where a patchwork of hand-cultivated onion fields gave way to small hilltop forests of tree ferns and hummingbirds. 

Petrified wood triggered memories of visiting a petrified forest during a long drive through Argentine Patagonia.

And this swollen trunk brought the name "palo borracho" to mind, a name that translates to "drunken stick", in reference to the bottle-shape of the trunk. They are common along the streets of Buenos Aires. I think this one is Ceibe speciosa, the silk floss tree, closely related to the kapok tree.

The Garden's 83 acres were donated by an accountant and businessman named Robert Montgomery, who counted among his friends the globetrotting plant collector David Fairchild, who lived next door and supplied many of the plants. The garden's website describes how Fairchild "visited every continent in the world (except Antarctica) and brought back hundreds of important plants, including mangos, alfalfa, nectarines, dates, cotton, soybeans, bamboos and the flowering cherry trees that grace Washington D.C." 

The National Tropical Botanical Garden goes even farther in describing Fairchild's legacy: 

"Avocado, mango, kale, quinoa, dates, hops, pistachios, nectarines, pomegranates, myriad citrus, Egyptian cotton, soybeans, and bamboo are just a few of the thousands, if not hundreds of thousands of plants Fairchild introduced to the United States."

The desire to import plants that could prove useful for food, fiber, and other uses dates at least back to George Washington and Thomas Jefferson, but gained intensity during the golden age of travel--the late 19th century when Fairchild began his career. Plants were considered so important to the economy and security of the nation that the U.S. Botanic Garden--a particular passion of George Washington's--was placed next door to the Capitol building. That's it down in the lower left of this map. 

To 21st or even 20th century eyes, the proximity of a botanical garden to the nation's center of legislative power feels odd in the extreme. Plants are more likely now to be viewed as quaint decoration to soften the edges of our hardened world. When I visited the U.S. Botanic Garden, probably in the 1990s, the conservatory looked a bit down in the mouth, largely serving as a refuge for the homeless. More respect for George Washington's dream has been shown since then. 

Those must have been heady times, early in the 20th century, when Fairchild oversaw the import of more than 100,000 species of plants from around the world. Their utility and beauty promised to enrich our country by diversifying our farms, gardens and kitchens. Few, including Fairchild, wanted to think about the downside, as some of these imports escaped gardens and ran wild over the landscape, displacing native species. A botanical enrichment has contributed over time to an ecological degradation. 

I looked into whether David Fairchild ever came to terms with the potential for introduced species to run amok, and plan to write about it in a separate post. He was aware that some nonnatives like kudzu and lebbek were spreading aggressively, but there is no verifiable evidence as yet that he sounded a warning. 

It's heartening to see that the Fairchild Tropical Botanical Garden itself has evolved to take the threat of invasive species very seriously. According to multiple sources, it monitors closely its collection of exotic plants and takes action to prevent spread beyond the Garden's borders. I want very much to believe all this is true and will continue to be true, the better to enjoy the memory of my visit there, encountering so many old (plant) friends from my earlier travels around the world. 

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.