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Sprawling Cities Can Coexist with Thriving Ecosystems

Many major urban areas are constrained with the amount of green space they can provide to residents. Encouragingly, building rooftops have emerged as a solution to fill this shortfall of urban green space.

Published January 1, 2004

By Peter Coles
Academy Contributor

Jacob K. Javits Center – New York City. Image courtesy of demerzel21 via stock.adobe.com.

The common image of cities as hot spots of crime and grime may need updating. They also can be havens of natural and cultural diversity – and could hold the keys to sustainable development in the 21st century.

While some 3.2 billion people – half the world’s population – are now estimated to live in towns and cities, with a growing number of poor, “urban” is by no means incompatible with “nature,” even in a major city like New York. Once rare, peregrine falcons now nest on Manhattan bridges, while a survey carried out by the Brooklyn Botanic Gardens found over 3,000 species of plants in a 30-mile radius of the city – far more than in the vast cornfields of the Midwest.

The Need for Preservation

And, while the presence of man has driven some species of plant and animal close to extinction, cities may now be the only places they are still found. Paradoxically, they will no longer survive without human intervention to preserve them.

These topsy-turvy ideas emerged during a meeting at The New York Academy of Sciences (the Academy) in October 2003, entitled “Urban Biosphere and Society: Partnership of Cities,” co-organized with CUBES (Columbia University-UNESCO Joint Program on Biosphere and Society) and UN Habitat.

For many people, the built-up environment is the antithesis of nature, as Rutherford Platt, of the Ecological Cities Project at the University of Amherst, pointed out. “Nature” is somewhere else, outside the city, in a national park or some remote wilderness. But, recalling Lewis Mumford, champion of the green belt, he emphasized that not only can nature be part of a city, but cities themselves can be as much a part of nature as an anthill or a beaver colony.

Creating New Types of Habitat

Ecologists are now appreciating that cities, as well as preserving rare patches of ancient flora and fauna in parks and settler cemeteries, also present challenging new habitats, with their own adapted plants. “We are creating types of habitat that have never been seen before,” said Charles Peters, Kate E. Tode Curator of Economic Botany at the New York Botanical Garden, “like a vacant lot with 35 minutes of sunlight a day. It’s an interesting niche.”

Peters, who has been studying a 40-acre swathe of ancient oak and hickory forest in the Botanical Garden for several years, also defended the invasive species that are settling there, filling niches left by native species that have failed to adapt to an urbanized habitat. “The most important thing is that these plants continue to function, whether they’re from China or Siberia. We can’t put the forest back the way it was 200 years ago. To do that, we’d have to put the Bronx back the way it was 200 years ago. Forests are continually changing. What’s important is that the new species are controlling erosion, providing nutrients for the soil, recycling the air.”

Others argue that intact, native ecosystems, like the remnants of oak woodlands and prairies in Chicago, have a far richer biodiversity than those colonized by invasive species, and are more sustainable. Since 1996, Chicago Wilderness, a loosely-structured coalition that today comprises over 165 associations, institutions and organizations, has been working to restore biodiversity in the Windy City, which is visited by some 6 million neo-tropical birds every year on their way to and from Canada.

Retaining Residents

Chicago’s city fathers, explained John Rogner, Chicago Field Supervisor of the Fish and Wildlife Service of the Department of the Interior, bought patches of oak woodland and prairie to prevent them being developed. Their argument was that a beautiful environment, with access to nature, would stop residents – the city’s life force – from moving away.

After three years of research, including “bio blitzes” in which local residents and children help scientists count species, Chicago Wilderness established a “biodiversity recovery plan.” With a wide range of projects, such as ridding the oak woodlands of tenacious, but non-native buckthorn, the consortium is also helping to restore brown-field sites, like Calumet, south of the city, which ironically contains several endangered and critical species of bird, surviving amid the derelict steel plants and toxic waste dumps.

Mark Wigley, interim dean of the Graduate School of Architecture at Columbia University, suggested that for most people “old cities are the heroes, and new cities are the villains.” But this idealized image leaves out the crime, open sewerage, disease and overcrowding characteristic of city life in the Middle Ages.

For Robert Pirani, director of environmental programs for the New York Regional Plan Association, the “villain” today is not so much the post-industrial downtown as it is suburban sprawl. In the past 10 years, he said, land use in the New York area has expanded by 100%, while population has increased by less than 10%.

Sprawling Cities

This means “thousands of homes surrounded by lawns, and shopping malls surrounded by parking lots,” he said. According to Rutherford Platt, this trend can be seen across the U.S., where suburban population has increased fourfold since 1950, compared to an 85% increase in population. And, he added, car ownership in the U.S. has risen by 100% since 1970, while population increased by 40%. In Atlanta, which has been dubbed “sprawl city,” drivers spend an average of 72 hours a year in gridlock, he said.

If sprawl is a middle-class phenomenon in developed countries, however, it is associated with poverty in much of the south. While 82% of Brazil’s population live in cities, said Rodrigo Victor, of the São Paulo Biosphere Reserve, some 23% of the population of São Paulo live in shanty towns, mostly on the edge of the Green Belt Biosphere Reserve that surrounds the city, a part of the Atlantic Forest Biosphere Reserve.

With a global trend towards urban living – two-thirds of world population in 2030 will live in cities – the challenge is to find sustainable solutions to urban growth. One approach, according to freelance journalist Helen Epstein, is through architecture itself.

A new generation of high performance buildings attempt to behave more like natural systems, with water management on site, passive solar energy production, natural lighting and ventilation reducing their “footprint,” or impact on limited natural resources. An example is the Solaire housing development in Battery Park City, Manhattan. But, as architect Ernie Davis, mayor of Mount Vernon, New York, pointed out, these buildings are not usually for the poor, whereas project housing, which is designed to look as though it’s for the disadvantaged, does not have advanced design features.

Green Rooftops in South Korea

Green rooftops also offer a solution, as Kwi-Gon Kim, professor of landscape architecture at Seoul National University, South Korea, demonstrated. With 42% of Seoul covered by buildings, landscaping rooftops could add an estimated 200 square kilometers of green space to the city, about 30% of the Seoul area. In an experimental green roof project on top of UNESCO’s downtown Seoul office, just five months after its construction the 75 species of plant introduced at the outset had been joined by an additional 39 species, presumably from surrounding green belt areas, while 37 species of insect had colonized the site.

Seoul was one of 11 cities invited by CUBES to prepare case studies to see whether, and how, the UNESCO “biosphere” model could be applied to urban areas. This model, designed 30 years ago, has since been applied in 440 UNESCO Man and the Biosphere (MAB) sites in 97 countries. These are areas of terrestrial and coastal ecosystems that promote the conservation of biodiversity with its sustainable use.

They are internationally recognized, nominated by governments, and remain under the sovereign jurisdiction of the states in which they are located. Usually, they consist of a “core” area that has minimum human impact, surrounded by a “buffer zone” and a “transition” area, with increasing levels of social and economic activity, respectively. But, while some of the sites adjoin cities (like São Paulo), to date there is no urban biosphere site as such.

A Future Urban Biosphere Site

Cape Town, South Africa, which is already surrounded by three natural biosphere reserves, gives some clues as to what a future urban biosphere site might look like, although it is just a theoretical case study at this stage. As Ruida Stanvliet, of the Western Cape Nature Conservation Board illustrated, the nine provinces in the region house 3.5 million people, some of them affluent and white, living in suburbs, while much of the black population lives in extreme poverty, in temporary housing and with a high incidence of HIV/AIDS. Nonetheless, the area boasts a rich biodiversity, with some 9,000 plant species.

“Environment conservation is crucial for poverty alleviation,” said Stanvliet. “It connects people to their sustainable resource base.” And in Cape Flats, one area in the Cape Town urban biosphere case study, over 20% of the people live in sprawling, informal settlements. In some communities, 70% live with less than $1 a day, and only 36% of adults are in paid employment.

The windswept mosaic of dunes and wetlands of Cape Flats is where victims of apartheid were relocated. Now, in a pilot initiative, the City of Cape Town has joined with the Botanical Society of South Africa, the National Botanical Institute and the Table Mountain Fund, to form Cape Flats Nature. This project focuses on conservation and restoration of biodiversity in several sites, enlisting the participation of local people through educational programs.

The Cape Flats Nature project has a certain resonance with the Chicago Wilderness brown-field development in Calumet, half way across the globe from Cape Town. This linking of cities, at least informally, was one of the ambitions of the Academy/CUBES meeting.

As Many Questions as Answers

The meeting raised as many questions as it answered, but that was another of its ambitions. In a city like New York, where would the “core” of a biosphere site be? For William Solecki, of the Department of Geography at Hunter College, City University of New York, it could be the harbor and estuary area, which is historically the focus of human activity in the city, while pockets of intact wetland survive in adjacent Jamaica Bay.

And the “buffer zone” might be the watershed in the Catskills that feeds the “core.” Indeed, as Christopher Ward, commissioner of the New York City Department of the Environment explained, New York was able to avoid spending millions of dollars on a new water treatment plant by investing in protection of the watershed.

This inclusion of more distant areas in the biosphere of a city like New York is a way to acknowledge that its “footprint,” unlike that of an equivalent natural area, can even extend thousands of miles. The coffee consumed in New York has a direct impact on plantations as far away as Bolivia, which, incidentally, is where some of the migrant warblers come from that feed in Central Park every May and October. Food for thought.

Also read:  The Impact of Climate Change on Urban Environments


About the Author

Dr. Peter Coles is a freelance science writer and photographer living in Paris, France.


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