2020 and the Tree of Resilience: Ailanthus altissima

Forty feet in the air, I perched hesitatingly on the uninviting, creaky metal slats of my friend Kate's rusty fire escape in Flatbush, Brooklyn. It was a deceptively cool summer morning in 2020 and one perfect for a coffee alfresco. I’d wedged myself “gracefully” through the apartment’s window moments before, managing not to send any notebooks or pens plunging below as I maneuvered myself, akimbo. At the window sill, Kate's dog, Djola, (and my charge for the weekend), had surveyed my acrobatics with concern until I found myself a seat. Savoring slow, quiet mornings like this one had become my standard: a coffee, a crossword, a few pages of a book. The cozy, quotidian sounds of muffled city traffic as background music, I settled down with that day’s offerings, content, and realized: I had always wanted to be here. Not so much here, literally, but here in the larger sense, in New York City—as my home.

The seed (pun intended) that planted my love for the Big Apple was sowed by Betty Smith in her classic 1945 novel, A Tree Grows in Brooklyn. On my mom’s urging (her mom had loved it as well), I first read the book in middle school at about the age we meet its protagonist, Francie Nolan. Francie was a balance between dreamy and observant, earnest, reflective, bookish; I identified with her and romanticized the New York City world she inhabited. I loved Smith’s rich descriptions of Francie’s life in Williamsburg in the early 20th century, particularly of the many characters Francie encountered as she walked her block or gazed out from the perch of her fire escape. Of all the neighborhood’s residents, the book opens with a description of its most famous one:

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“The one tree in Francie’s yard was neither a pine nor a hemlock. It had pointed leaves which grew along green switches which radiated from the bough and made a tree which looked like a lot of unopened green umbrellas. Some people called it the Tree of Heaven. No matter where its seeds fell, it made a tree which struggled to reach the sky. It grew in boarded up lots and out of neglected rubbish heaps and it was the only tree that grew out of cement.” [1]

On the fire escape in 2020, I could easily have been looking out at the same scene. A tree effortlessly towered over the 6-story apartment buildings that crowded it. Its canopy lent dramatic shadows that covered the dusty and cement yards below; I followed the outstretched branches with my eyes, tips to the trunk, to really make sure they all came from the same tree (they did).

What tree was this?

I’d been finding comfort over quarantine by asking myself questions like this. For an animal- and nature lover, I knew (still know) shockingly little about the flora and fauna of home. I challenged myself to finally learn — and then be able to identify — the plants growing outside my window. During the city’s shelter-in-place, Leslie Day’s Field Guide to the Natural World of New York City accompanied me when I left my apartment for short walks to the grocery store or laundromat; I opened my eyes more on those trips, those moments that were Not-in-My-Apartment.

In Flatbush, perusal of the field guide once again gave me my answer: “lacy” leaves, tiny, green clusters of flowers, and a dizzying height, I had found the Tree of Heaven itself, or Ailanthus altissima [2].

Like Francie and me, many others have been captivated by the Ailanthus. A native of China, the Tree of Heaven was first brought to North America in 1784 by a William Hamilton for his Philadelphia country estate. The tree’s tropical look and generous, expanding canopy had earned it popularity in Europe as a hardy, fast-growing ornamental. Enthusiasm only grew following its commercial introduction to the United States — and New York — in 1820, by Prince Nursery in Flushing, Queens.

Growing up to 3 feet of height per year, Ailanthus saplings provided a quick solution for bringing fresh air and higher real estate values to choked, industrialized city streets across New England and the Mid Atlantic (and later West, during California’s Gold Rush). In New York City, trees-of-heaven grew — and, clearly, continue to grow — across all five boroughs. By 1862, a report by the Brooklyn Horticultural Society named Ailanthus the most popular street tree in Brooklyn, making up an estimated 43% of Brooklyn’s “canopy.” “For many years," remarked William Prince, Jr., a prominent horticulturalist of the time, "it was impossible to supply the demands [for Ailanthus], at treble the former prices, when everyone gazed on it with wonder and admiration.” [4]

New Yorkers’ enthusiasm for the Tree of Heaven was quickly overtaken by the trees themselves.

Once a welcome addition to any street corner, trees-of-heaven might have soon been expected on every one. Within only 30 years of its introduction to the city, editorials in The New York Times called upon “every man who has an ailanthus tree in his neighborhood [to] make it his duty to destroy it” [4]. A tree-of-heaven “fills the air with a heavy, sickening odor...and over runs, appropriates and reduces to beggary, all the soil of every open piece of ground where it is planted,” lamented A. J. Downing in 1852, editor of The Horticulturalist and Journal of Rural Art and Rural Taste [4]. Today, Ailanthus altissima is designated a “noxious weed” by the United States Department of Agriculture [5], not for its smell — said to be like burnt peanut butter during the summer [6] — but for its prowess at proliferation.

"[They] would be considered beautiful except there are too many of it" [1]

Now, what makes trees-of-heaven so good at being so invasive?

These trees are precisely the scrappy survivors Francie Nolan saw growing “out of cement” in Betty Smith’s Williamsburg. They excel at growing in poor soil in general, whether that be heavy clays, polluted lands, city rooftops, or all of the above. The species’ shallow, widespread, and fast-growing roots can tear apart a building’s foundations and grow from the rubble of long-gone buildings themselves [5]. Once established, adult Ailanthus altissima produce upwards of 350,000 seeds a year, each with a high germination rate, or chance they will sprout and turn to saplings. The trees can also reproduce asexually, via cloning, through a process called root suckering: clonal offshoots of a tree can grow from roots far away from its trunk, and these may even pop up after the tree has been felled. To make matters worse for those aiming to control Ailanthus’ spread, the tree is allelopathic, releasing toxins into the soil that stymie the growth of any plants nearby. Welcome to the neighborhood.

In short, whether it is wanted or not, the Ailanthus altissima is made of sterner stuff.

Plants like the Tree of Heaven fit into the “new ecology of vacancy” described by Sean Burkholder [6]. As cities age, unkempt sites within them are left forgotten, uncultivated — think abandoned parking lots, halted construction, and long-unoccupied houses. Here, pioneer plant species, or those first to grow after a disturbance, are quick to stake their claim. Following WWII, for example, trees-of-heaven colonized areas of rubble and destroyed buildings when other plants did not; it was purposefully planted to rehabilitate mine spoils in the eastern United States and other post-industrial wastelands (a practice no longer recommended) [3]. “Vacant” land, therefore, is likely not vacant at all.

While invasive species are of course precisely that — invasive, damaging, often-unwanted — vacant land might not need to be immediately written off. As Burkholder questions, “...can vacant land, through the provision of ecosystem services, become a resource as opposed to a liability?” and “how?” [7, p. 1154, emphasis added]. In Madagascar, where I work, might fallow fields and former logging sites hold some promise for conservation aims, rather than serve as an impediment? As human and natural spaces become increasingly indistinguishable, I’m interested in studying — in appreciating — the ecology “of” human environments, rather than the ecology “within” them [7].

“Vacancy,” in parallel, has come to be a term I’ve associated with 2020, and particularly with New York City’s experience of the pandemic.

“Historically, the discipline of urban ecology focused on the ecology “within” the city, while more recent work has been done to understand the ecology “of” the city” [7, p. 1156]

In May, my roommate and I walked from our Astoria apartment to Times Square. Aside from a few costumed characters, the Naked Cowboy (masked!), and a couple other passersby, it was just us and the flashing lights. It felt as empty as the sidewalks of my own block, where fellow pedestrians and I would exchange furtive glances as we sidestepped one another during runs for yet-more-sanitizer at the local CVS. The ‘city that never sleeps’ was on PAUSE, dormant (apart from the now-ever-familiar sounds of sirens). Today, it might still be mistaken for “vacant.”

 What New York City is is resilient. Like the Tree of Heaven, NYC thrives after disturbance. It makes use of poor conditions; it persists in them. In my neighborhood, in March, flyers for the Astoria Mutual Aid Network started cropping up almost as soon as the stay-at-home orders were issued.

“Need someone to buy your groceries?” the posters read, “We can help! Feeling lonely? Need information about how to keep yourself safe? We can help!” Volunteering for AMAN — delivering contact-free groceries across Queens, stocking and sorting at the neighborhood’s pop-up food pantry, answering non-stop calls as an AMAN dispatcher — seeing videos of the daily 7 pm cheers from across the city and countless other examples of New Yorkers’ resilience...it all (selfishly, I thought) held me afloat. In truth, these reminders of the good in humanity and of the strength of human perseverance pulled me through a disturbing and general malaise that had been stifling me since before 2020 even started. Now, for all of us: we will get through. And, when you can, take your equivalent of a fire escape retreat and see what wonders the life just outside your window can offer.

Written with immense gratitude to New York City’s essential and health care workers and deepest sympathy to all those personally affected by COVID-19

Cited Sources
[1] Smith, B. (1945) A Tree Grows in Brooklyn. New York: Harper Perennial Modern Classics.
[2] Day, L. (2007) Field Guide to the Natural World of New York City. Baltimore: The Johns Hopkins University Press.
[3] Sevik, H., Ozel, H. B., Cetin, M., Özel, H. U., & Erdem, T. (2019). Determination of changes in heavy metal accumulation depending on plant species, plant organism, and traffic density in some landscape plants. Air Quality, Atmosphere & Health, 12(2), 189-195.
[4] McNeur, C. (2018, January 4). The Tree That Still Grows in Brooklyn, And Almost Everywhere Else. [Blog Post]. Retrieved from https://gothamcenter.org/blog/the-tree-that-still-grows-in-Brooklyn-and-almost-everywhere-else
[5] Fryer, J. L. (2010). Ailanthus altissima. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Retrieved from https://www.fs.fed.us/database/feis/plants/tree/ailalt/all.html
[6] Global Invasive Species Database. (2020). Species profile: Ailanthus altissima. Retrieved from https://www.iucngisd.org/gisd/species.php?sc=319
[7] Burkholder, S. (2012). The New Ecology of Vacancy: Rethinking Land Use in Shrinking Cities. Sustainability, 4,  1154-1172.
[8] Collins, G. (2008, March 27). A Tree That Survived a Sculptor’s Chisel Is Chopped Down. The New York Times. https://www.nytimes.com

Additional Resources & Interesting Reads
On Ailanthus & Cities
Collins, L. M. (2003, December 10). Ghetto palm. Detroit Metro Times. https://metrotimes.com
Karen (2015, July 23) The Tree of Heaven in Washington Square. [Blog Post] Retrieved from https://www.villagepreservation.org/2015/07/23/the-tree-of-heaven-in-washington-square/

On Ailanthus Ecology
Kasson, M. T., Davis, M. D., & Davis, D. D. (2013). The invasive Ailanthus altissima in Pennsylvania: a case study elucidating species introduction, migration, invasion, and growth patterns in the northeastern US. Northeastern Naturalist, 20, 1-60.
Mori, S. (2015, August 13). Tree of Heaven: An Immigrant Thriving in New York and Beyond. [Blog Post] Retrieved from
https://www.nybg.org/blogs/science-talk/2015/08/tree-of-heaven-an-immigrant-thriving-in-new-york-and-beyond/
USDA NISIC. (2020). "Tree-of-Heaven." United States Department of Agriculture National Invasive Species Information Center. Retrieved from https://www.invasivespeciesinfo.gov/terrestrial/plants/tree-heaven#cit
USDA NRCS. (2020). “Ailanthus altissima (Mill.) Swingle Tree of Heaven.” Plants Profile for Ailanthus altissima (Tree of Heaven), United States Department of Agriculture Natural Resources Conservation Science National Plant Data Team. Retrieved from https://plants.usda.gov/core/profile?symbol=AIAL#

On Prince Nursery
QNS TimesLedger. (2004, April 22) Discovering history at Flushing's Botanical Garden. [Blog Post] Retrieved from https://qns.com/2004/04/discovering-history-at-flushings-botanical-garden/
Smithsonian Libraries (n. d.) Prince, Robert. Retrieved from https://www.sil.si.edu/silpublications/seeds/princerobert.html
Walsh, K. (2015, February 24) A Historic Pair in Flushing and East Elmhurst. [Blog Post] Retrieved from https://www.brownstoner.com/development/a-historic-pair-in-flushing-and-eastelmhurst/

For Fun: All the [Insert Here] Grown in Brooklyn
Doll, J. (2012, September 17) A Headline Grows Old in Brooklyn. The Atlantic. https://www.theatlantic.com Retrieved from https://www.theatlantic.com/culture/archive/2012/09/headline-grows-old-brooklyn/323580/

Image Credit
Ailanthus altissima Fast Facts corner images: Tree-guide.org
Prince Nursery: Overview of Flushing, New York (1876), Queens Historical Society
Noguchi Museum: The Isamu Noguchi Archive, noguchi.org
Ailanthus at the High Line, prior to clearance: Joel Sternfeld, villagepreservation.org
Times Square: Angela Weiss / AFP-Getty Images

Planted Header image: Utsman Media on Unsplash

All other images are my own.