This is an article that many of you might already have seen, but since it
came my way again, and (to my mind at least) has obvious implications for
field recording / phonography (terms which have recently generated some
debate on the phonography list), I thought I'd pass it along. Apologies
to anyone who isn't interested or has seen this or related articles
before.
-i
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November 23, 2002
Wild Cities: It's a Jungle Out There
By ALEXANDER STILLE
or most of her career, Christine Padoch did her environmental research in
distant, exotic locations like the rainforests of Amazonia and Borneo,
while Steven Handel studied evolution in the Galapagos Islands. Now Ms.
Padoch, an ecological anthropologist, takes the subway from her job at the
the New York Botanical Garden in the Bronx to count exotic vegetables at
the green markets of Queens, while Mr. Handel, a professor of evolutionary
biology at Rutgers University, is studying the vegetation that grows along
the tracks of the New Jersey transit railway a true test, if ever there
was one, of the survival of the fittest.
Their projects are examples of the new frontier of environmental studies:
urban ecology.
Until recently, the only real environments thought worth studying were in
"pristine" nature, remote areas as far as possible from the footprint of
human beings. Cities, by contrast, were seen as unnatural,
nonenvironments, whose parks and gardens, ornamental plants and scraggly
sidewalk trees and weeds were of as little interest to ecologists as house
cats and lap dogs are to big game hunters.
Now, though, ecologists are finding that cities are interesting,
legitimate environments, with surprisingly high levels of biodiversity,
and what's more, that understanding and protecting them may be crucial to
our environmental future.
>From Paris, Rome and Cairo to New York, Baltimore and Phoenix, cities are
all subjects of intense ecological study. Unesco is even thinking of
making several major cities, including New York, biospheres, important
natural areas to be protected, joining ranks with such traditional natural
wonders as Yellowstone and Yosemite national parks.
"If Darwin were alive today, he might be studying Staten Island instead of
the Galapagos," said Mr. Handel, who is, in fact, working to re-introduce
native North American species to a portion of what was, until recently,
North America's largest garbage dump, the Fresh Kills waste site.
That ecologists have gone from studying Darwin's finches to counting
papayas and mangos at the Hunt's Point market in the Bronx, as well as the
nearly indestructible flora and fauna that survive inside the vacant lots
and abandoned industrial sites of the world's cities, is part of a much
broader maturation of the field, several environmental scientists say.
"The original idea that ecology involved trips to faraway places that
people would consider to be pristine reflected a very deep-seated belief
that people and nature are separate, which has been dominant in ecology,"
said Steward Pickett, a senior scientist at the Institute of Ecosystems
Studies in Millbrook, N.Y., who is conducting a major long-term study of
the environment of Baltimore. The foundations of ecological thinking, he
said, were shaken by studies in the last 25 years that showed that
virtually all "pristine" environments bore clear signs of human
intervention: fires, the hunting of animals, the harvesting of plants,
herbs, nuts or fruits.
"There is no area left in the world that has not undergone serious human
impact, and this makes the whole planet a man-made planet, and cities are
only the extreme example of that," said Christine Alfsen-Norodom, the
coordinator of Columbia University and Unesco's joint program on the
biosphere and society.
The shift to urban ecology is also linked to a series of changes in the
environment itself: increased urbanization, metastasizing sprawl and
global warming. "The choice is no longer between cities and wildness," Ms.
Alfsen-Norodom said. "It is, in the face of increasing population, between
density and sprawl."
Density and verticality, the hallmarks of big cities, were once bad words
in an ecologist's vocabulary but are now seen as invaluable allies. By
concentrating large numbers of people in limited areas, they leave
substantial areas for forests, meadows, wetlands and the wide open spaces
needed for many species to survive. "If large numbers of people didn't
live concentrated in cities, the world would be a nightmare," Ms.
Alfsen-Norodom added.
As ecologists have begun to study city environments, they have been
surprised at the level of biodiversity they contain. "In the New York
metropolitan area, within a radius of 50 miles, we have recorded over
3,000 plant species: 2,000 native species and 1,000 introduced to the
area," said Steven E. Clemants, vice president for science at the Brooklyn
Botanic Garden.
As the Hudson River has made a comeback, sea horses have been spotted in
the Gawanas Canal, and rare centipedes have recently been found in Central
Park. New York City is, in fact, a major bird sanctuary. The marshy
wetlands of Jamaica Bay near Kennedy airport are among the biggest nesting
areas on the East Coast, and big patches of green like Central and
Prospect parks look like landing pads to birds migrating north and south
with the seasons. Thus, some rather unexpected species the American White
Pelican, the Pied-Billed Grebe and the Red-Throated Loon can be seen in
New York City, while the Downy Woodpecker and the Rock Dove live here year
round.
This is not as unlikely as it may seem, Mr. Clemants says, when you
consider that New York has a higher percentage of open space some 25
percent of its land surface than any major city in the United States.
As ecologists have come to accept the "impure" nature of urban
environments, they have been re-evaluating the role of exotic plants,
imported species that have traditionally been regarded as noxious,
aggressive pests crowding out native North American species. As a result,
there is an intense debate between ecological purists who are trying to
conserve and bring back native species and those who feel that exotic
plants are the victims of biological xenophobia.
"If we value the composition and the diversity of native species, then we
do have to be concerned about exotic species," Mr. Pickett said. "The
other side of the story is that in many urban environments, the exotics
are particularly good at dealing with harsh urban conditions."
Because the sidewalks, paved streets and tall buildings make the city
hotter and its soil drier, plants originally from tropical environments do
extremely well here. If you look through a subway grate and see a tree
growing at the slimy bottom, ecologists say, it will almost certainly be
an Ailanthus, known as the Tree of Heaven, from China and the Korean
peninsula. They grow at a rate of two meters a year and survive in soils
that would kill most plants. Indeed, of the 3,000 plant species found in
New York, fully a third were introduced from somewhere else.
"We owe a lot to invasive species," said Charles Peters of the botanical
garden in the Bronx. "They are able to grow and reproduce in the extremely
screwed-up environment. Over the decades, there is an increase of
nonnative species. The natives are dying out or having trouble
reproducing. The exotics, like the Tree of Heaven, are continuing to
prevent soil erosion, maintaining the cycling of nutrients, pumping out
oxygen and providing shade where native species don't go."
Mr. Handel, who is co-director of the Center for Urban Restoration Ecology
at Rutgers, insists that while obviously an exotic species in a place
where nothing else will grow is fine, people should not be too cavalier in
accepting the demise of native species. Because they are often less
aggressive, they allow for a higher number of different plants in their
midst, while the most successful exotic plants are so aggressive that they
leave no room for others.
"The final result is a poorer, more monotonous environment," Mr. Handel
said. But with care, as in Fresh Kills and in Flushing Meadows on grounds
once occupied by the World's Fair, native species have made a solid
comeback, he added.
While Mr. Peters supports some of these efforts, he thinks some of
restoration ecology's hopes are unrealistic. "Already, 20 percent of the
trees in the Brooklyn Botanic Garden are exotic, and that's a protected
island in an urban sea," he said. "We've examined the soil, and it's
filled with dormant seeds of the Tree of Heaven just waiting for an
opportunity to grow. The average oak may grow 1,000 acorns a year and they
all fall near the tree, while the average Tree of Heaven will send off
gazillions of winged spores that go everywhere. The acorns all get eaten
by squirrels because there are no predators around. You can subsidize the
plants that are not very good in this environment or just let the best man
win."
But exotic species can also create problems. In Colorado, Patrick
Bergeron, a French ecologist at the University of Colorado in Boulder,
said that the sprawl around cities like Denver and Boulder has radically
changed the landscape: "Diversity has increased. The trees mitigate the
effect of pollution and attract birds and animals, but they are pumping
water like crazy and the whole area is thirsty for water."
Moreover, he explained, because much of Colorado is a semiarid landscape
that will not naturally support trees, the added "biodiversity" has made
the area extremely vulnerable to fire. In a more sparse, unpopulated
landscape, fires can serve to regenerate the soil, but in a populated area
with lots of trees, fires can spread more easily and become much more
dangerous, as they have become in recent summers in the Western United
States.
Nonetheless, efforts to support native species do not always work, Mr.
Bergeron points out. Ecologists in Phoenix, for example, discovered that
people there who were trying to cultivate native species ended up watering
them as much as cultivated, exotic plants rather than allowing them to
rely on their own resources.
One of the reasons for the shift to urban ecology, says Cynthia
Rosenzweig, a senior research scientist at NASA and the Earth Institute,
is an increased awareness of global warming. "Climate change is a global
phenomenon," she said, "and so it becomes easier to see the links between
cities and other environments."
Moreover, says Ms. Rosenzweig, who helped direct the first extensive study
of climate change in the New York metropolitan area, global warming has
already begun to affect the city environment. Tropical plants like kudzu,
the highly invasive Japanese vine that covers almost every tree in
Southern states like Georgia would never have survived an old-fashioned
New York winter, but in recent years it has been found growing in downtown
Manhattan.
"As we are thinking about the effort to restore the harbor estuary, the
Fresh Kills dump site and the wetland areas," Ms. Rosenzweig said, "we
need to take projection on climate change into account, or we may be
attempting to save or restore something that may not be there."
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