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americanelm.jpg

By Erik Baard

The American Elm teaches us about how grandeur and delicacy, strength and vulnerability, can rise from the same roots. And how ubiquitous splendor can so suddenly become rare.

Step outside this weekend and watch these often supercentanarian monuments bringing forth delicate flowers, a pointillist expression. “They are small flowers that give an overall hue or yellowish orange and red across the whole tree instead of seeing individual flowers,” said Jessica Arcate, curator of woody plants at the New York Botanical Garden in the Bronx, which boasts specimens in natural habitat that pre-exist the institution’s 1891 founding.

“They weren’t planted there. They seeded in and grew naturally in the middle of our forest,” she said. “They like our flood plains, swales, run offs, and vernal pools.”

Calling their branch form “winged,” Arcate first fell in love with this largest species of elm while working on an estate in the Hudson River Valley. “They have such a full, almost weeping canopy. They’re just spectacular trees.”

The American elm in the NYBG photo above, taken March 26, can be found in the Benenson Ornamental Conifers collection. Arcate cautions that no photo can do them justice. Perhaps the words of Oliver Wendell Holmes, Sr. description of coming upon one over a hundred feet tall and in full leaf might help:

“…I saw a great green cloud swelling in the horizon, so vast, so symmetrical, of such Olympian majesty and imperial supremacy among the lesser forest growths, that my heart stopped short, then jumped at my ribs as a hunter springs at a five-barred gate, and I felt all through me, without need of uttering the words, ‘This is it!’”

Finding a large stand of American Elms is elation itself, and always a product of nature guided by human artifice. Central Park designers Frederick Law Olmstead and Calvert Vaux planted The Mall, best reached via the East 66th Street or East 72nd Street entrances, with four rows of American elms flanking the promenade. The flying buttresses of prodigious branches arc until they clasp in a vault of joyous green-gold in mid-spring’s leaf flush and by summer fill in to create a hushed enclosure of uncrowded communing. This is our city’s Great Nave.

Native Americans used the trees as landmarks for gatherings, and derived medicines for ailments ranging from coughs to obstetrics. European colonists also fell for them fast and hard. While much of the continent was still wooded, town elders had wild American elm saplings planted in the Boston Common. As the U.S. population boomed, American elms became a street tree of choice, lining both grand boulevards and sleepy suburban tracts that sprang up along railroad lines. Part of this preference stemmed from their hardiness, in terms of temperature range and native pests, including hundreds of insect species. Utility also played a role; the high arcing branches that give American elms their distinctive vase or umbrella shape shade streets while allowing traffic to pass.

Today the pleasure of spending time among American elms is a rare privilege by which light New Yorkers are spoiled. We have some of the world’s largest stands, notably in Central Park and Riverside Park. Though wild American elms were once most abundant in the eastern United States, they now survive in substantial numbers primarily in Midwest and Canadian prairies.

We descended to that sad state following the 1930 introduction of Dutch elm disease, a fungus that hitched aboard logs shipped from Europe. The vector for transmission is the European elm bark beetle.

“Borers tend to go to trees that are stressed out, so they went for the street trees first,” Arcate said. Healthy trees in the niche for which they have evolved deploy natural defenses that can thwart attacks that would fell street trees.

“There’s research indicating that some trees give off an infrared shade that changes when they’re sick. Insects flying around know it,” she said. Once set upon by the fungus, the decline and mass death was visible to human eyes. Trees yellowed and weakened in vast waves. Miles of American roads were left sun scorched in summer and hauntingly barren in winter. Communities were stripped of their sense of place.

Remaining urbanite American elms demand constant monitoring and intensive care from stewards like the New York Department of Parks and Recreation. Keeping them alive, however, is still cheaper than letting them die. Removing a dead American elm can cost in one shot as much as providing decades of care, to say nothing of adjacent property values. As Michael Pollan notes in a brilliant essay about species, their survival is a civic effort. In a sense, they have become our city’s arboreal humpback whales or polar bears, massive and strong yet begging for care after the damage we’ve introduced.

 

Efforts to hybridize or otherwise alter the American elm to resist the blight have shown progress, but the “holy grail” of an immune tree that perfectly retains the beloved form remains elusive.

But the battle isn’t entirely defensive — foresters are replanting thousands of American elms, hundreds by the Natural Resources Group of the NYC Parks alone, in recognition of its central ecological role.

As with what animal conservations call “charismatic megafauna,” saving the signature species can serve as a vehicle for broader ecological protection. Elms in the wild thrive when surrounded by dense associations of tree species, and special regional relationships have evolved. In New York you’ll often find American elms in the company of white ash, slippery elms, rock elms, yellow birch, black tupelo, sycamore, eastern hemlock, bur oak, swamp white oak, and silver maple.

American elm leaf litter decomposes into soil that unusually rich in soil-improving elements, including potassium and calcium, which as electrolytic minerals can eventually prove valuable for flood plain animals as well as undergrowths and ground covers. “We know amphibians are there. Groups comes to count the tadpoles,” Arcate said. In 2004, an Audubon Chicago study found that American elms were strongly preferred by migratory birds. Butterflies rely upon them for nectar and as a place for larvae to develop.

It’s hard to imagine, when standing before a single American elm, how many organisms have made a world for themselves from the vernal pools gathered at its roots to the “green cloud” above. Sadly, we need no imagination to conceive of the vacuum that would follow neglect.

  

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