The image of cities as hotbeds of pollution, stress, poverty and crime needs an update. They are also havens of natural and cultural diversity – and may hold the keys to sustainable development in the twenty-first century. While some 3 billion people worldwide are now estimated to live in towns or cities, with a growing number of poor, cities are by no means incompatible with rich biodiversity. Settler cemeteries in Chicago have preserved some of the oldest oak trees in the region, peregrine falcons nest on Manhattan’s bridges and there are more species of leafy plant in a 30-kilometre radius around Brooklyn than in the vast farmlands of USA’s mid-West. Meanwhile, highly built-up Seoul (Republic of Korea) is finding that rooftop green spaces provide “stepping stones” of biodiversity, where some long-banished species are returning.

To take this ‘new look’ at cities even further, counsellors, planners and other urban stakeholders from cities around the world, including New York and Chicago (USA), Cape Town (South Africa), Dar es Salaam (Tanzania), Montevideo (Uruguay), Rome (Italy), São Paulo (Brazil), Stockholm (Sweden), and Seoul (Republic of Korea), are meeting with scientists and conservation specialists in a two-day conference on “Urban Biosphere and Society: Partnership of Cities” to be organized by Columbia University, UNESCO and UN-Habitat on October 29 – 30, at the New York Academy of Sciences, which is also co-sponsoring the event.

One anticipated outcome of the meeting is the creation of a partnership between these cities to pool experience and expertise on a long-term, regular basis. And under consideration will be the usefulness of sustainable development tools, such as UNESCO’s ‘biosphere reserve’ concept, already applied for over thirty years in 440 sites in 97 countries. Although some of these sites include cities, so far no urban area has used this model to look at the interplay between social, economic and environmental issues in sustainability. Some cities, like Rome and Seoul, are actively looking into the applicability of the UNESCO urban biosphere reserves concept.

To look at some of the challenges and opportunities offered by treating urban environments as dynamic biospheres, in 2000 Columbia University’s Earth Institute teamed with UNESCO and its Man and the Biosphere (MAB) programme to form CUBES (the Columbia University-UNESCO Joint Program on Biosphere and Society). CUBES has since invited case studies from eleven cities. Research findings from several of these case studies will be presented at the two-day meeting in New York. Other presentations will deal with specific aspects of urban sustainability, such as respiratory ailments linked to pollution in Mexico City, and mechanisms to improve public participation in urban environmental decision-making.


Some urban ecology initiatives

* New York Metropolitan Region

The New York Metropolitan Region is one of the most urbanized regions in the world, with a total population of 21.5 million, 8 million of them living in New York City. But the region has some 2413.5 kilometres of coast shoreline and four of the five New York City boroughs are located on islands. With urbanization, many of the region’s vulnerable and critical habitats – especially wetlands – have been degraded. The few remaining habitat sites, like Jamaica Bay, an hour’s subway ride from central Manhattan, still provide critical ecological functions, such as stopping-off points for migratory bird species. As clean-up efforts have progressed, these sites have witnessed a noticeable increase in species richness over the past decades. The wetlands also provide a buffer against a forecast rise in sea level with global warming. This function, though, has been dramatically reduced by landfill and construction, which prevents the wetlands ‘retreating’ inland to absorb sea level rise.

The New York Metropolitan Region case study is studying how the biosphere model can be adapted to provide a set of tools for sustainable development linked to conservation of biological and cultural diversity. Whereas in classical biosphere reserves, there is a core conservation area, with minimum human impact, surrounded by a buffer zone, in an urban biosphere reserve, the ‘core’ might even lie outside the densely-inhabited areas. And unlike a traditional biosphere reserve, the function of the core in an urban area like New York, might be as a focus for the region’s social and cultural activity and identity, rather than as a hotspot of biodiversity. In New York, a potential ‘core’ area would be the New York/New Jersey harbour and estuary area.

The case study also looks at the so-called ‘footprint’ of the city – ie. its impact on natural resources. On the one hand the footprint can be global, as it encourages, for example, turning fields over to monoculture coffee plantation in distant countries. But the footprint of a high-rise development, per capita, is also much smaller than a suburban area of similar population.


* Green rooftops for Seoul

Around 42% of Seoul is covered with buildings. Open land is scarce and market forces favour development, making green spaces inhabited by wild animals scarce. But, by landscaping the city’s rooftops, an estimated 200 square kilometres of green space could be created, - approximately 30% of the Seoul area. To further this idea, Seoul city government now actively promotes rooftop greening, paying for structural safety survey costs. It has already provided funding for 10 sites, in addition to a pioneering project on the top of UNESCO’s downtown field office building. In UNESCO’s rooftop site, just 5 months after its construction, the 75 species of plant introduced at the outset had already been joined by a further 39 species, presumably from surrounding green areas, while 37 species of insect had colonized the site.

In addition to the experimental green rooftop scheme, Seoul also has a 167 square kilometre greenbelt around its perimeter, limiting uncontrolled sprawl. It includes forest, dry fields and rice paddies and is complemented by a patchwork of green spaces in the city that could potentially be linked by green corridors. This complex forms the basis for plans to form a city-wide urban biosphere reserve.


* São Paulo City Green Belt biosphere reserve

São Paulo, with its 18 million inhabitants, is the world’s fourth largest urban agglomeration. In 1994, the 1.5 million-hectare São Paulo City Green Belt Reserve was established as part of the UNESCO Atlantic Forest Biosphere Reserve, following a petition signed by over 150,000 people. Apart from its diverse ecosystems, including rain forest, cultivated areas, savannas and water bodies, the Green Belt biosphere reserve provides opportunities for youth training in subjects such as ecotourism, organic farming, land rehabilitation, waste recycling and small-scale food production. Over 500 students have already followed the courses. The biosphere reserve has also become an important forum for promoting citizenship and environmental debates and has already resulted in drastic modifications to a planned highway scheme.


* Cape Town Case Study

Cape Town, in the south west of the African continent, has a population of about 3.5 million. Two UNESCO biosphere reserves already exist in the surrounding rural areas and a third is currently being proposed. The Cape Town urban biosphere case study, though, includes the Cape Flats area, where some 20% of the population lives in sprawling, informal settlements. In some of its communities, over 70% of residents live below the poverty line. Unemployment is high, with only 36 percent of adults in paid employment. The windswept mosaic of dunes and wetlands of Cape Flats is where victims of apartheid were relocated out of white areas. 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 programmes.