Street trees have to have much more than a pretty face. Like "street kids," their survival depends on being resilient and tough as nails. After all, they deal with the worst of planting conditions, compacted soil, narrow planting beds, pollutants, exhaust, and frequent road construction. In this Arbor Day issue meet the toughest of the tough -- albeit with exquisite faces -- coming to a street near you!
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For the past several decades, Glen Ridge has been losing its mature street trees at a ferocious pace, due to the aging out of those planted in the early 20th century and the climate-change-driven syndrome of “maple decline.”
So, despite having planted close to 1,200 trees since 2011, there are currently only 228 additional street trees. And a third of the town’s mature trees have been replaced with saplings. Consequently, it is no longer just a question of planting trees, but of planting those trees that will make the greatest aesthetic and environmental contributions to the town 50 or 60 years hence.
(Pictured, a mature
Willow Oak)
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Bigger Is Better
Studies show that big trees provide exponentially greater benefits than small trees. A University of Pennsylvania study concluded that just three mature London planetrees sequestered as much carbon as did 1,400 small trees combined. However, many homeowners are understandably reluctant to plant big trees near their homes. Plus, it is heat-absorbing streets that are most in need of shading.
Bigness, however, is not the whole story: Fullness of the canopy, hardiness and longevity are also important factors. Last but not least, native species must be prioritized.
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Mature Trees:
*provide cooling
*absorb great amounts of carbon dioxide
*purify the air
*produce oxygen
*soak up gallons of runoff water
*prevent flooding
*filter and sequester potentially dangerous microscopic organisms and pollutants
*aspirate moisture into the air, stimulating rainfall
*provide crucial shelter to wildlife in an increasingly precarious ecosystem.
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Scientists estimate that butterfly and moth populations have decreased by 70 percent. And, in turn, the resultant loss of caterpillars has contributed to the estimated 3-billion decrease in bird populations. Therefore, it is extremely significant that oak trees host far more butterfly and moth caterpillars than any other tree species. Meanwhile, their acorns provide vital food to over 100 vertebrates. Thus it is not surprising that swamp oaks, scarlet oaks, and willow oaks will predominate in the spring planting. All 3 varieties make excellent street trees, tough, strong, wind- and disease-resistant.
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The inclusion of willow oaks is a reflection of climate change. As the planet warms, plant species (and, unfortunately, invasive insects) are steadily migrating northward. That is a key reason why maples are no longer thriving in our area.
So, whereas the swamp and scarlet oaks are native to NJ, the willow oak is native to the south-central US, where, reputedly, they were Thomas Jefferson’s favorite tree. As such, planting them in NJ is a hedge against future warming. As distinctive as their origins is their show-stopping appearance. Like their fellow oaks, willow oaks develop lofty, rounded canopies. But, as their name implies, they feature narrow, pointed, “willow”-shaped leaves (see photo), which provide a lovely, dappled shade. It is for this reason that they are often referred to as the “handsome tree” species.
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The word “hardy” does not do this tree justice. Indeed, this species can handle whatever urban conditions are thrown at it, including pollution, compacted soils, and narrow planting beds. A cross between the American sycamore and the Asian planetree, this tree embodies the best of both. (How can you tell which is which? The sycamore has one seed ball on a stem, the Asian planetree has three, so the London planetree has two.)
Interestingly, this hybridization came about naturally at Kew Gardens near London in the late 17th century. But that is not the tree’s only association with London. It was essentially the only species that could survive that city’s epic air pollution at the end of the 19th century. The fact that these trees are spectacularly beautiful, especially because of their exfoliating bark, was obviously an added benefit. Indeed, London planetrees have been planted extensively in Glen Ridge since the early 20th century. Remnants of allees of them can be found on several streets, including Midland, Clinton, and Carteret.
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The Resurrected American Elm
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The elm was unquestionably America’s favorite tree in the 19th century, as reflected in the many streets named “Elm.” Elms seemed the perfect street tree for developing towns and cities: hardy, long-lived, and fast-growing, but also exquisitely vase-shaped with feathery leaves.
Beginning in the 1930s, Dutch elm disease (DED), an invasive Asian blight that spread first to Holland and then to the US, began relentlessly killing millions of them, prompting The New York Times in 1932 to dub it “the nightmare on Elm Street.” By 1957, Glen Ridge had lost over 600 elms to the disease. (Today, a few survivors remain on the Municipal lawn and one in front of RAS.) Motivated by the devastating loss of this iconic tree, teams of horticulturalists worked for decades to develop DED-resistant elms. So, once again, these lovely, native trees can grace our streets.
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The Inaptly Named Black Gum (aka Black Tupelo) |
The black gum tree, also referred to as the black tupelo or sourgum tree, deserves a much better name – one that more positively represents this gem of a tree. Perhaps because of its dour-sounding name, Glen Ridge only began planting this native tree along our streets some eight years ago. But it has become a fan favorite!
Black gums stand out for their rich canopies of deep green and glossy leaves, which turn yellow, orange, red or purple in the fall. Admittedly, their late-spring blossoms are not showy by human standards, but they delight pollinators, especially honeybees. Similarly, their bluish-black fruit (seen above) provides a much-needed supply of food for birds into the winter months. That fruit is also edible by humans and can be used in pies and jams.
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Celebrate Arbor Day! Please take care of and enjoy our street trees! |
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The Shade Tree Commission wants to be your resource on all things "trees." If you have concerns, questions or issues, do not hesitate to contact us at shadetree@glenridgenj.org |
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Elizabeth Baker, Chair
Larry Stauffer
Joan Lisovicz
Robert Baum
Tina Seaboch
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