Why concrete jungles need green spaces
CAN cities really become home to a large variety of fauna and flora? Doesn’t the wild world hate cement? The concept of biodiversity may seem to contradict the nature of cities, but scientists, designers and architects are working on urban development models that harmonise with the natural environment.
The world is increasingly urban. If contemporary trends continue, the metropolitan area of Bogota, Colombia, for example, will triple between 2000 and 2030, and the city’s population will grow from 3-million to almost 5-million.
Globally, this urban expansion will use up space and natural resources, especially water and farming land. It will happen more in regions with fewer economic capabilities and faster in regions with more biodiversity, as a 2012 report on biodiversity and cities concluded. This should not surprise us, as areas of rich biodiversity are precisely those that have always attracted human settlements and fomented trade.
The evidence about the presence of a wealth of fauna and flora in large cities may come as a surprise. More than 50% of flower species in Belgium are in Brussels, and Warsaw is home to 65% of all bird species in Poland.
A study of 61 gardens in Sheffield, England, found 4,000 types of invertebrates, 80 types of lichens and more than 1,000 plants.
THERE are significant nature reserves in cities such as Cape Town, Mumbai, Stockholm, Nairobi and Tucson, Arizona, all of which make crucial contributions to biodiversity in those cities. These spaces improve the health and well-being of city residents by cutting noise and air pollution.
“They are not so much complementary and secondary as vital to cultural activities, physical and mental health and the identity of a place,” says Maria Angelica Mejia of Bogota’s Humboldt Institute.
In Sacramento, California, park joggers under 65 years typically spend $250 less on medicines than people who do not exercise. Other studies show that proximity to trees can reduce child asthma and allergies.
Cities are thought to emit 70% of all greenhouse gases — which makes urban green spaces, whether they be parks or roof gardens, vital in mitigating climate change.
These are the “soft infrastructures” that regulate the microclimate — the weather immediately around them — filter rainwater and absorb smog and excess dust. A UK study found that a 10% increase in city green cover reduced temperatures by 3% to 4%, which in turn reduced the widespread use of air conditioning.
Legal frameworks for protecting biodiversity include the United Nations Convention on Biological Diversity signed by 193 parties in 1993, and Colombia’s own National Biodiversity Policy, adapted for Bogota and Medellin, though only the latter has developed an action plan to implement its provisions, initially in the form of pilot projects.
Luis German Naranjo, the conservation chief for the World Wildlife Fund in Colombia, cites the country’s interventions to rescue biodiversity, such as saving Bogota’s wetlands and revitalising the banks of the Sinu River in Monteria. But he adds that “management of biodiversity in Colombian cities is ever precarious”. Parks, for example, are seen as recreational spaces, not ecosystems that improve air quality or as habitats for plant and animal species.
CONSERVATION International’s Patricia Bejarano says Colombia has barely begun to make the link between cities and biodiversity.
“For a long time nobody paid attention in city planning to issues of biodiversity and its benefits. Now environmental problems have become more serious and more relevant around the world,” she says.
“Cities like Bogota, Medellin and most recently Monteria have made some advances in recovering ecosystems and their regional surroundings, and this has been through linking the environment with development plans.”
City development and biodiversity must now be systematically linked, she suggests. She cites examples of the ravines that have been restored in Bogota to become tourist destinations that are also appreciated by the capital’s residents.
“It is interesting how in Bogota, the recovery of certain gorges has allowed citizens to understand the real importance of ecosystems, not just for preventing or mitigating risks but to improve air quality.
“And the proof of this is that most people have begun opposing building projects in the city’s eastern mountains,” Ms Bejarano says.
Cities must change their perspectives on development, neither halting construction because of biodiversity, says Humboldt’s Maria Angelica Mejia, “nor abandoning everything that is green”. New York Times