Urban Conservation in New York City
by Molly Marquand
Originally published on Izilwane
Where every great city stands today, a natural ecosystem once thrived. London was built on a floodplain of the River Thames; New York was set up on great tracts of oak woodland; and Tokyo, the most populous metropolis in the world, once supported a lush and verdant subtropical forest. Since their ambitious beginnings, cities all over the world have sacrificed natural diversity to become the cultural, artistic and economic centers they are today. The very definition of the word urban excludes notions of nature and rurality, instead conjuring images of industry and skyscrapers. But in an increasingly green-minded world, many cities are working to reverse their reputations and are redefining the concept of urbanity altogether.
The Big (Green) Apple
Take New York City, for example. The Big Apple is home to more than eight million people and covers 305 square miles (790 sq.km). The city is the financial powerhouse of the world and a mecca for arts, technology, and cultural diversity. New York is also one of the greenest metropolises in the country: Not only does it boast the highest levels of public transportation use, but its citizens consume less than half the energy of the national per capita average. Compared to San Francisco, where plastic bags are illegal and municipal composting is the norm, New York far out-ranks the ecologically conscious California city, contributing almost 30 percent less per capita in annual greenhouse gas emissions.
Part of what makes New York so green is its size. The confines of Manhattan Island, an area of only 23 square miles (60 sq. km), have directed development upward in the form of skyscrapers that are now recognized all over the world as the city’s trademark skyline. The apartments Gotham residents call home are notoriously small—and expensive—but are far more ecologically responsible than their lawn, dishwasher and central air-equipped suburban equivalents. The demand for limited space in New York continues to escalate as population levels grow and the pace of development maintains its momentum. For the most part, this isn’t anticipated to change New Yorkers’ habits and the city’s claim to green fame. It may, however, disrupt another aspect of the city’s environmentally friendly nature—namely the unprecedented amount of woods, wetlands and meadows that thrive within the boundaries of this formidable metropolis and occupy some of the most desirable real estate in the country.
Natural New York
New York City encompasses many diverse geologic areas and is home to a multitude of different habitats. When European settlers first arrived in New York Harbor more than four hundred years ago, they found the landscape a verdant patchwork, knitted together by abundant streams, swamps and waterways. One of the most prominent habitat types, the upland oak forest, occupied more than ten thousand acres (2,590 hectares) on Manhattan, covering the island from what is now Wall Street to Harlem. In hot, dry summers, the oak forest became a veritable tinderbox that periodically burst into flame, clearing out snags and dead trees, opening the canopy, and maintaining the plethora of herbaceous species that prospered on the well-lit forest floor. In autumn, pounds of the oaks’ rolling acorns littered the understory, providing food for bears, moose and raccoons, as well as Native Americans. As New York City grew in global importance, however, the wild woods were gradually hacked back. Wall Street, so named for the stone wall that kept the wilderness neatly out, exceeded and bulged over its own confines in a mere matter of years.
Despite having grown to become the most populous city in the United States, a quarter of New York’s area is dedicated to open space. Most visitors to New York make a trip to see the city’s most famous undeveloped area, the iconic Central Park. Opened in 1857 in response to the city’s growing population and an increased need for recreational green space, the park covers 843 acres (342 hectares) and includes ponds, swamps, streams, fields and large tracts of woodland. The park has long been a favorite destination of birders who come to see, among other species, the famous peregrine falcons (Falco peregrinus) that nest on the buildings along the park’s perimeter. For botanists, Central Park is home to one of the largest remaining stands of American elm (Ulmus americanus), a species that has almost been extinguished since the introduction of Dutch elm disease in the 1920s.
Compared to the rest of New York City, however, the natural offerings of bucolic Central Park are paltry. Depart from the heart of Manhattan and the same unaltered ecosystems that occurred in the pre-settlement era can still be seen and explored. More than 2,100 plant species can be found within New York City—more than in the entire country of Great Britain—and some of these species are exceedingly rare. Staten Island, the fastest growing borough in the city, is home to the globally vulnerable Torrey’s mountain-mint (Pycnanthemum torrei), a plant found in fewer than twenty locations worldwide. The American chestnut (Castanea dentata), a once-abundant tree in northeastern forests, can still be found in several locations in New York City, as well. The most notable of these occurrences are also on Staten Island, where several individuals have resisted the blight responsible for decimating the species long enough to reproduce and set fruit.
The southwestern edge of Staten Island is home to the globally-rare post oak-blackjack oak community. Situated upon millennia-old exposed sand deposits, the soil of this habitat is arid, nutrient poor and highly acidic. Walking through this ecosystem in the summer, lurid tufts of acid-loving moss flanking the trail and carpets of low fruiting blueberries dominating the forest floor, it is hard to accept this community’s designation as a part of New York City. Similarly, a 134-foot (41 m) tulip tree (Liriodendron tulipifera), rumored to be four hundred years old, resides in Alley Pond Park, Queens, making the usual descriptions of New York City seem erroneous and incomplete. From the glacially scarred rocks that protrude in Riverside Park to the easily flooded areas in Chelsea where ancient underground streams surge to reclaim lost ground, remnants of the city’s past ecological landscape persevere almost everywhere. Pelham Bay Park in the Bronx only recently lost its final Native American inhabitant in the late 1920s. Underground stone larders and rock drawings are still visible where the last tribe of Algonquians settled for their summer camp.
Environmental Changes and Challenges in New York
Preserving the habitat wherein biological diversity occurs requires preserving large amounts of often contiguous green space, a commodity that is in high demand for development in New York City. In 2000, a 3.4-acre (1.38 hectare) property in the center of Manhattan famously sold for $345 million, or approximately $2,300 per square foot. Exorbitant prices belie the area’s robust economic activity and overall desirability. As vacant land disappears and suitable habitat is lost to development, plant populations shrink and become geographically isolated. Separated by vast expanses of concrete, these once-conjoined populations may no longer be able to breed. Reproductive isolation causes the critical gene flow between populations to weaken or even stop, increasing the incidence of inbreeding. Genetic diversity is necessary to maintain species fitness and the essential ability to adapt to new and changing conditions over the long term. As gene flow slackens, the likelihood of genetic divergence, inbreeding depression and extinction increases. And so species vanish, extirpated from the landscapes they have occupied since the last ice age.
In a study by Dr. Robert DeCandido, New York City was found to have lost 43 percent of its native flora since 1925. Of the original 1,357 native species found in the city, only 779 remain. Staten Island, the most floristically diverse borough in the city, has lost 40 percent of its native plant species just in the last century. The majority of these extirpated species were seen in citywide surveys conducted in 1879 and 1930; it is only in the last seventy years, with the opening of the Verrazano-Narrows Bridge and the borough’s subsequent population boom, that these species disappeared. Currently, more than 33 percent of the species remaining on the island are exotic, and despite numerous introductions of alien species, the total number of plant taxa continues to decline.
Conservation efforts face immense challenges under the pressure of New York City’s prodigious urbanity. Even the simplest of well-intentioned management practices, such as blazing trails, create problems. Meant to facilitate public access and enjoyment of the parks, trails act as gateways into forest interiors for invasive species, particularly exotic grasses. The visitors themselves may even enable the advance of exotic species: One study found that as park use and number of visitors increased, incidence of invasive species increased.
The tireless spread of foreign invaders is just one of the problems effective ecological management must remedy. The overall degradation of native soils due to pollution and compaction is one of the biggest, and most difficult to mitigate, threats to native flora in New York City. A number of species rely on fungi found only in intact native soils to survive. Orchids represent the best example of this ecological relationship: The city has lost approximately twenty-four species of orchids that were recorded until 1990. Now, only six genera and six species remain. An exotic orchid, the broadleaf Helleborine (Epipactis helleborine), is the only orchid species out of an original twenty-one that currently grows in Manhattan. A large number of ericaceous species (members of the blueberry family), so vital to New York City’s once-dominant upland oak woodland community, rely heavily on Ascomycota ericoid mycorrhizae, fungi found on plant roots, to efficiently absorb nutrients in the soil. The displacement of native soil, in combination with outright habitat destruction, has made the blueberry family one of nine families with an extirpation rate of at least 50 percent.
The cessation of disturbance events, particularly cyclical fire regimes, plays an important role in the character of New York City’s contemporary plant communities. Resinous canopy trees, high summer temperatures, frequent lightning storms and strong winds traditionally contributed to frequent natural fire cycles in the city’s various habitats. Many species found in the oak woodland communities of New York City are fire-resistant, sprouting from stolons, or as in mountain laurel (Kalmia latifolia), from a protected underground root burl. Because of the city’s high population density, natural wildfire cycles are no longer permitted to occur. Fast-growing invasive species fill tree-fall gaps that create similar forest openings suitable for light-loving species, such as huckleberry (Gaylussacia baccata) and lowbush blueberry (Vaccinium pallidum), before natives have a chance to become established. Invasive species also alter soil nutrient and pH levels, thus inviting late-successional species into the forest and encouraging growth of non-native types of woodland vegetation. The resulting landscape is a tangled mess of invasive vines, broad-leaved, quick-growing trees, and a homogenous understory of shade-tolerant shrubs and herbaceous species.
The Natural Resources Group (NRG), a division of the New York City Department of Parks and Recreation created in 1984, is responsible for management and preservation of the city’s green spaces. In an effort to preserve some of the city’s more pristine habitat, the Natural Resources Group proposed legislation that would protect ecologically valuable areas from further fragmentation and degradation. The Forever Wild sites, as they are known, are selected based on criteria such as the existence of intact native soils and undisturbed upland forest, wetlands or tidal marshes within the preserve. Sites known to contain rare species or habitat, such as the dwarf juneberry (Amelanchier nantucketensis)—occurring on Staten Island and only a handful of other places in the world—also receive consideration for this extra measure of protection. Globally rare communities, such as the post oak-blackjack oak barrens community, are overseen by the state of New York, rather than the city. Forever Wild sites are not impervious to the problems that plague the rest of the city’s green space, however. Disrespectful, destructive use of these preserves by the public still occurs, and invasive species are present in even these most pristine areas.
Conservation in the Urban Environment
There’s no denying New Yorkers appreciate their open space. Anyone who has seen Central Park on a beautiful summer day knows how much residents value a green slice of grass or the irresistible cool of a sliver of shade. In a city as large as New York, people are both a burden and a boon to native plant conservation. As development pressures continue to increase, so do the efforts of conservation groups like the Torrey Botanical Society and Protectors of Pine Oak Woods. The New York Botanical Garden, a world-class garden and herbarium, has been documenting and conserving urban floral diversity since the 1800s. The garden also provides botanical teaching for the public through classes, field trips and regularly published journals. Activist groups involved in restoration projects, invasive plant removal and citizen agency in New York City’s environmental policies have flourished in recent years, as well.
One particularly successful organization, the NYC Wildflower Week, uses city inhabitants’ natural thirst for the outdoors for an environmental purpose. Helping the public engage with the environment through guided walks and lectures, the organization aims to instill a sense of ownership and pride in city green spaces. Knowing the names, evolutionary history or habitat requirements of the city’s different plants sparks a sense of wonder and encourages stewardship. Topics discussed include native alternatives for the city garden and edible plants of the five boroughs.
One of Wildflower Week’s partners, the Greenbelt Native Plant Center, collects seed from local native plant communities. Some of this seed is cultivated at their extensive Staten Island nursery and used in restoration projects across the city. The rest is packaged into seed mixtures or sent to global seed banks like the one at Royal Botanic Gardens at Kew, in England. Sourcing local material for restoration projects ensures plants will be as best-suited to the growing conditions of the New York area as possible. Although a species may successfully range from Maine to North Carolina, geographically distinct populations evolve different adaptations to cope with ecological variations such as climate. A red maple (Acer rubrum) from Maine, for example, may not be able to tolerate hot, humid New York summers.
The Greenbelt Native Plant Center also lists a number of species appropriate for green roofs on their website. Greenroofing originally gained popularity due to its mitigating effects on storm run-off and extreme temperature fluctuation. Recently, it has become one of the many ways urbanites are bringing nature back into the pandemonium of city life. Green roofs are also one of the most feasible ways to conserve native species and create green space. Over the past few years, farms and apiaries have taken to the skies, too, growing food and constructing bee hives on otherwise vacant space. A current study on roofs planted with native species reveals the habitat attracts a plethora of insects, including those from the diminishing order Hymenoptera—the bees and wasps. Projects such as The High Line, an abandoned elevated tramway turned public garden on Manhattan’s West Side, are thrusting native plants into the stratosphere of “cool.” In October, as masses of migratory birds wheel overhead in their ancient, timeless ritual, the garden’s fruiting plants provide fuel for their long journey. The garden serves as an important public model, demonstrating the holistic benefits of using ecologically appropriate plants in an urban setting.
By 2025, two-thirds of the population will live in urban centers. While this may boost public transportation use and help eradicate suburban sprawl, the conservation of city green space will be more challenging than ever. Fortunately for New York City, nature and its advocates are as gritty and resilient as New Yorkers themselves. Native plants and ecosystems reclaim lost ground quickly and have been found exploiting new and surprising niches only available in urban environments. The nutrient poor, thin soils on landfills are underlain with a clay lens used to cap the mound. This mixture of substrate inadvertently creates perfect habitat for, among other things, members of the threatened blueberry family. Fresh Kills landfill on Staten Island, one of the largest piles of garbage on the planet, is slated to be the site of an equally large native plant restoration project in the newly created Freshkills Park. In only a handful of years, a meadow of native grasses will sway over the landfill’s hump, preventing erosion, providing habitat for ground-nesting birds and sowing ecologically appropriate seed for miles around. New Yorkers will be free to wander the park, run on its trails, and admire its flora and fauna. Perhaps there is no better symbol of the unification of nature and urbanity—and the rewriting of their relationship—than this budding partnership. Instead of mutual exclusion and antagonism, the two entities nurture each other: New growth is literally sprouting from city detritus, and the city, in turn, is richer, greener, healthier and happier because of it.
Photos are copyright protected and cannot be reproduced without permission. Image of Central Park used with the permission of Flickr Creative Commons Attribution License 2.0 Generic and is courtesy of Patrick Ashley[http://www.flickr.com/photos/patashley/]. All other images are courtesy of Molly Marquand.
Molly Marquand is a gardener, botanist and writer based in New York’s Hudson Valley. She completed her B.A. at Bates College in Maine and received her M.S. from Reading University’s Plant Diversity and Taxonomy program, which is run in conjunction with the world renowned Royal Botanic Gardens at Kew in England. Most recently, Molly has been working with various organizations on native plant conservation in New York City. True to her academic background in science all of Molly’s writing and gardening reflect careful consideration of ecology and nature. In her free time she enjoys riding her horse and hiking with her dogs. Molly is the current horticultural editor of Wilder Quarterly.
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